Cooled mechanical circulatory support system and method of operation

Abstract

To provide a mechanical circulatory support system for a heart having a cooling element, and a method for using the system to treat an effect of a cardiac episode.SOLUTION: A pump has a distal end and a proximal end, and comprises a rotor having at least one blade. The system also has a catheter having a distal end, a proximal end, an inner surface, and an outer surface, the catheter extending proximally relative to a pump housing. The outer surface of the catheter is configured to contact blood when disposed within patient vasculature. The outer surface includes a heat transfer surface configured for cooling blood that comes in contact with the outer surface. The cooling element can be either a helix or double helix extending along a catheter surface, or a Peltier element on the surface. The support system is operated to provide a temperature selected to cool the circulating blood in contact with the outer surface of the catheter to a temperature selected to reduce or prevent an effect of a cardiac episode.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 62 / 836,534, filed April 19, 2019, entitled "Cooled Impella," the disclosure of which is incorporated herein by reference. [Background technology]

[0002] background Mechanical circulatory assist systems, such as intracardiac or intravascular blood pumps, may be introduced into the heart to deliver blood from the heart to the arteries. Such mechanical circulatory assist devices are often introduced to assist the function of the heart after a patient has suffered a cardiac episode. One such type of device is a series of devices known as the "Impella" heart pump. Some blood pump assemblies may be introduced percutaneously through the vascular system during cardiac surgery. Specifically, blood pump assemblies may be inserted via catheterization into the ascending aorta through the femoral artery or axillary / subclavian artery, through the aortic valve, and into the left ventricle. The inserted blood pump assembly may be configured to take blood from the left ventricle of the heart through a cannula and then eject the blood into the aorta. The blood pump assembly may also be configured to take blood from the inferior vena cava and then eject the blood into the pulmonary artery. Some mechanical circulatory assist devices are powered by an internal motor, while others are powered by an external motor and drive cable. Still other blood pumps use an external pump located outside the patient's body and a long catheter that extends through the vascular system to the heart or other desired location. Some blood pump systems are surgically implanted rather than catheter-based.

[0003] Cardiac episodes that require the use of a blood pump can typically cause many adverse effects to the patient. Such cardiac episodes include myocardial infarction, cardiac arrest, high-risk percutaneous coronary intervention, cardiogenic shock, and left and right ventricular failure. In particular, patients who experience a myocardial infarction, more commonly referred to as a heart attack, may be left with extensive scarring of the heart tissue. Such scarring alters the normal conduction pathways of the heart and weakens the affected muscles. Depending on the size and location of the scarring, patients may be at increased risk of arrhythmias, heart block, ventricular aneurysms, inflammation of the heart wall, and rupture of the heart wall, all of which can be fatal. It is therefore highly desirable to reduce or prevent such myocardial scarring. Summary of the Invention

[0004] One known method of treating scarring from myocardial infarction is systemic hypothermia induction, which rapidly cools the blood flowing through the patient's heart to a desired systemic temperature. For example, the desired systemic temperature may be lower than the patient's normal body temperature (e.g., less than 5 degrees Celsius). Sufficient reduction in temperature of blood to the desired systemic temperature via systemic hypothermia cools the heart, thereby slowing many physiological processes in the heart, such as metabolic reactions, tissue death, and myocardial scarring. However, current use of systemic hypothermia induction is known to cause arrhythmias in patients, which is particularly problematic in patients with myocardial scarring whose hearts are already weakened. Thus, to minimize the undesirable effects of myocardial scarring and to minimize the undesirable effects of hypothermia induction, it is desirable to have a system that can simultaneously systemically cool blood flow to prevent or reduce myocardial scarring while also preventing arrhythmias.

[0005] The systems, methods, and devices described herein provide a mechanical circulatory support system, e.g., a blood pump system, configured to systemically cool a patient's blood while simultaneously reducing the workload of the heart. The blood-contacting surface of the blood pump or other circulatory support system can be configured as a heat transfer surface to provide systemic cooling. When the heat transfer surface of the catheter of the pump system contacts the blood circulating through the patient's vascular system, the blood can be rapidly cooled, which can remove sufficient heat from the blood to induce a systemic hypothermic effect in the patient. The induced hypothermic effect slows biological processes that cause or exacerbate the undesirable effects of a cardiac episode. However, since inducing systemic hypothermia can cause arrhythmias, hypothermia therapy is induced simultaneously with standard operation of the blood pump or other circulatory support system. In this way, the systemic hypothermia induction method can reduce (or reverse) the undesirable effects of a cardiac episode while the blood pump or other circulatory support system circulates blood in the vascular system, thereby improving the nutritional status of the heart (and other vascular systems) to prevent or avoid the undesirable effects of the systemic hypothermia induction method. The systems, methods, and devices described herein can be used to treat a variety of vascular conditions, including, but not limited to, myocardial infarction, cardiac arrest, high-risk percutaneous coronary intervention, cardiogenic shock, and left and right ventricular failure. In many applications, the systems described herein are blood pump systems for providing mechanical circulatory support to the heart (e.g., by unloading the heart) while cooling it. Generally, blood pump systems have a pump with a rotor having at least one blade that rotates within a pump housing that surrounds the blade. Generally, the pump is driven by a motor. Some pumps are powered by an internal motor, while others are powered by an external motor and drive cable. Other pump systems have an external pump that is placed outside the patient and a long catheter (or cannula) that extends within a blood vessel to the heart (or other location in the vascular system). Applications of the systems of the present disclosure may further include a catheter extending from the proximal end of the pump.Other adaptations may include surgically attached pump systems. In some embodiments, a flexible, atraumatic protrusion extends from the distal end of the pump. For example, the flexible, atraumatic protrusion may be a pigtail.

[0006] According to some aspects, the systems described herein include an intravascular cooling surface that induces hypothermia. The cooling surface extends along the length of the catheter, or other intravascular surface of the system, and is configured to be placed within the vasculature to contact blood circulating within the patient. In some embodiments, the cooling element may be formed as a heat exchanger with the blood, or may function by cooling the outer surface of the catheter, which then cools the blood circulating in the patient's vasculature as the blood contacts the outer surface of the catheter. A similar cooling system may be applied to another part of the blood-contacting surface of the auxiliary system (e.g., pump housing), either instead of the catheter or to enhance the heat transfer effect of the catheter. In some adaptations, the heat transfer element is applied directly to the outer surface of the catheter (or other system component), so that the outer surface (blood-contacting surface) of the catheter is directly cooled; in such adaptations, the blood may be in direct contact with the heat transfer element. In another adaptation, heat transfer occurs indirectly by placing a heat transfer element within the thickness of the catheter wall or along the inner surface of the catheter, thereby first cooling the inner surface or thickness of the catheter wall, which in turn cools the outer surface of the catheter by conduction through the thickness of the catheter wall.

[0007] At least one advantage of incorporating a cooling element into the pump system is that the temperature of the blood (and systemic blood vessels) can be regulated to prevent the undesirable effects of a cardiac episode while simultaneously preventing the undesirable effects of the regulated temperature (e.g., systemic induced hypothermia).

[0008] According to a first aspect of the disclosure, a blood pump system for a heart includes a pump. The pump has a motor, a rotor, and a heat transfer surface configured to be inserted into a patient and to be temperature regulated, for example, by a cooling element. The pump has a distal end and a proximal end. Generally, the rotor has at least one blade for conveying blood through the pump. In some embodiments, the cooling element may be configured as a lumen configured to deliver a cooled solution along the length of the catheter to provide thermal fluid cooling. In another embodiment, the cooling element may be configured as a Peltier element configured to deliver an electric current along the length of the catheter to provide thermoelectric cooling. The Peltier element may include a wire configured to deliver an electric current to a junction of two semiconductor materials. The semiconductor junction may be located at any suitable point along the length of the catheter. Similarly, the semiconductors may be oriented in any suitable configuration to induce a desired heat flow along the length of the catheter. In some embodiments, the power source that delivers the electric current to the Peltier element is the same as the power source that powers the pump. In another embodiment, the power source that delivers the electric current to the Peltier element is an external power source that is different from the power source that powers the pump.

[0009] The system further includes a pump housing that surrounds at least one blade of the rotor. In an intravascular application, a catheter extends from a proximal end of the pump housing. The catheter has an inner surface, an outer surface, a proximal end, and a distal end. When the catheter is placed in a patient's vasculature, blood flows over the outer surface of the catheter. The pump system may alternatively be surgically attached without a catheter, and the pump (or its cannula) may have a configuration of Peltier elements or other cooling elements.

[0010] In catheter applications, the cooling elements extend along the length of the catheter, and the cooling elements may be arranged in a variety of configurations. The cooling elements may have a cross-section that is circular, elliptical, diamond, rectangular, linear, or other shape. The cross-sectional geometry can be adjusted to adjust the percentage of the catheter's inner surface that contacts the cooling element. For example, in an embodiment having a circular cross-section, increasing the cross-sectional area allows a greater portion of the catheter's inner surface to contact the cooling element, increasing the rate of heat transfer and the total amount of heat transferred.

[0011] According to some aspects, the cooling element may contact the catheter or other blood-contacting system component to provide thermal control of the component and thus provide the desired thermal control and / or regulation (e.g., cooling) of the blood. The cooling element may also be configured to increase the temperature, e.g., increase the temperature of the blood, if necessary. To cool the vasculature, the cooling element cools the blood-contacting surface of the catheter (or other system component) to a temperature lower than the systemic temperature of the blood. For example, in many applications, the temperature to which the blood-contacting surface of the catheter is cooled may be about 32 degrees Celsius). In some aspects, the cooling element contacts the outer surface of the catheter or other system component. In other aspects, the cooling element contacts a portion of the inner surface of the catheter (either via a side-lumen or embedded within the wall of the catheter or other system component), in which the cooling element cools the inner surface of the catheter to a lower temperature, which then cools the outer surface of the catheter by conduction. In some embodiments, the cooling element may extend along the length of the catheter and then further into another system component. For example, another system component into which a cooling element may extend is the pump housing. Thus, the exterior surface of the catheter may be indirectly cooled to a desired temperature (e.g., lower than the systemic blood temperature) and the exterior surface may cool blood in contact with the exterior surface of the catheter or other system component. The blood in the heart is cooled until the desired systemic temperature is achieved. The cooling may be rapid. For example, the blood may be systemically cooled for a period of about 5 minutes to about 20 minutes. In another embodiment, the period is about 7.5 minutes to about 17.5 minutes. In further embodiments, the period is about 10 minutes to about 15 minutes. In some embodiments, the period is about 12.5 minutes. In certain embodiments, the blood is cooled for less than 5 minutes. In another embodiment, the blood is cooled for less than 3 minutes.

[0012] In certain embodiments, the whole body temperature to which blood is cooled is less than 37 degrees Celsius. In some embodiments, the whole body temperature to which blood is cooled is about 30 degrees Celsius to about 35 degrees Celsius. In another embodiment, the whole body temperature to which blood is cooled is in the range of about 31 degrees Celsius to about 34 degrees Celsius. In a further embodiment, the whole body temperature to which blood is cooled is about 32 degrees Celsius to about 33 degrees Celsius. Cooling the blood circulating in the patient produces a hypothermic effect that slows the biological processes responsible for causing or exacerbating the harmful effects of a cardiac episode. Specifically, cooling the blood can slow the processes responsible for causing myocardial scarring in the patient's heart after the patient has suffered a myocardial infarction, while the simultaneous pumping of the heart prevents the adverse effects known to be induced by systemic hypothermia-induced therapy.

[0013] In some embodiments, the cooling element may be configured as a lumen, and the lumen may be configured to deliver a cooled solution along the length of the catheter. Infusion of the cooled solution into the lumen may induce a hypothermic effect in the patient. To provide this hypothermic effect, at least a portion of the lumen may be a lateral lumen in contact with a portion of the inner surface of the catheter. Alternatively, at least a portion of the lumen may be embedded within the wall of the catheter. The particular portion of the lumen selected to be in contact with the inner surface of the catheter or embedded within the wall of the catheter may be selected to achieve a desired heat transfer rate along the portion of the catheter. Particular heat transfer rates at different regions along the length of the catheter may be beneficial in treating adverse effects of particular cardiac episodes. For example, in some embodiments, half of the lumen may be in contact with a portion of the inner surface of the catheter. In another embodiment, three-quarters of the lumen may be in contact with a portion of the inner surface of the catheter. Similarly, half of the lumen may be embedded within the wall of the catheter. In another embodiment, three-quarters of the lumen may be embedded within the wall of the catheter. The flow of cooled solution cools the inner surface of the catheter, thereby cooling the heat transfer surface of the catheter. The heat transfer surface of the catheter then cools the blood, inducing a hypothermic effect in the patient. The lumen has a first proximal opening and a second proximal opening. The first proximal opening may be configured as an inlet for the cooled solution, and the second proximal opening may be configured as an outlet for the cooled solution. The lumen may be configured to include two portions, a first flow portion and a second flow portion, both portions extending along the length of the catheter. The first flow portion extends from the first proximal opening to the distal end of the catheter and accommodates a distal flow of the cooled solution from the proximal end of the catheter to the distal end of the catheter. The second flow portion extends from the distal end of the catheter to the second proximal opening and accommodates a proximal flow of the cooled solution from the distal end of the catheter to the proximal end of the catheter. The first and second flow portions may extend the same length of the catheter. The first flow portion may be from a first proximal opening at the proximal end of the catheter to the distal end of the catheter, defining a first lumen path length along which the lumen extends.

[0014] The first lumen path length may be equal to the length of the catheter along which the lumen extends. The second flow portion may be from a distal end of the catheter to a second proximal opening at a proximal end of the catheter, defining a second lumen path length along which the lumen extends. The second lumen path length may be equal to the length of the catheter along which the lumen extends. In some embodiments, the first lumen path length may be greater than the second lumen path length. In another embodiment, the first lumen path length may be equal to the second lumen path length. The length of the catheter along which the lumen extends may be three-quarters of the length of the catheter. In another embodiment, the length of the catheter along which the lumen extends may be one-half of the length of the catheter. In certain embodiments, the lumen extends along the entire length of the catheter. The length of the catheter along which the lumen extends allows the cooled solution to be delivered along the same length of the catheter. In such an embodiment, after the chilled solution is injected into the first proximal opening and the fluid extends along the first flow portion, it extends along the second flow portion and exits the system from the second proximal opening. At least one advantage of a blood pump configured with a lumen for receiving a chilled solution is that the pump may induce systemic hypothermia to treat undesirable effects of a cardiac episode while simultaneously reducing the workload of the heart to treat undesirable effects of systemic hypothermia, including arrhythmias.

[0015] The lumen may be arranged in the catheter in a variety of different ways. In certain embodiments, the lumen may be configured to contact the inner surface of the catheter. For example, the lumen may extend along a first flow portion that defines a first lumen path length, but may be configured to contact the inner surface of the catheter. The first flow portion may extend along any suitable path, including but not limited to a straight line or a spiral. The lumen may then be configured to extend through the center of the catheter along a second flow portion that defines a second lumen path length. In another embodiment, a portion of the lumen may be embedded within the wall of the catheter. For example, the first flow portion of the lumen may be embedded in the wall of the catheter while the second flow portion extends through the center of the catheter. In another embodiment, the first flow portion of the lumen may extend through the center of the catheter while the second flow portion is embedded in the wall of the catheter. In certain embodiments, both the first flow portion and the second flow portion are embedded in the wall of the catheter. The second flow portion may also be configured in a variety of geometric shapes, including but not limited to a straight line or a spiral. Keeping the second flow portion out of contact with the inner surface of the catheter keeps the solution that has already absorbed heat from the blood away from the inner surface of the catheter, allowing for a more rapid temperature drop of the blood. The specific orientation of the lumens within the catheter may be adjusted to direct heat both to and from different regions along the length of the catheter.

[0016] In addition, the flow of the cooled solution may be configured to be reversible within the lumen. As described above, the lumen may be configured to extend along the length of the catheter from a first proximal opening at the proximal end of the catheter to the distal end of the catheter. The lumen may extend along the length of the catheter in various ways. In some embodiments, a portion of the lumen may be in contact with the inner surface of the catheter. In other embodiments, a portion of the lumen may be embedded within the wall of the catheter. Generally, the lumen is configured to receive a cooled fluid. The cooled fluid cools the surface of the catheter, which cools the heat transfer surface of the catheter by conduction of heat. This heat transfer surface induces a systemic effect on the patient's blood. In such an embodiment, the cooled solution may be injected into the first proximal opening, which may function as an inlet for the cooled solution, and the cooled solution may flow along the first flow portion from the proximal end of the catheter to the distal end of the catheter. In such an embodiment, the fluid can travel along the second length of the catheter from the distal end of the catheter to the proximal end of the catheter to the second proximal opening, with the second proximal opening acting as an outlet for the cooled solution. The flow of the cooled solution may be configured to be reversible within the lumen, so that in another embodiment, the cooled solution can first be injected into the second proximal opening, with the second proximal opening acting as an inlet for the cooled solution, and the cooled solution can flow along the second flow portion from the proximal end of the catheter to the distal end of the catheter. In such an embodiment, the fluid can return to the first proximal opening along the first flow portion from the distal end of the catheter to the proximal end of the catheter, with the first proximal opening acting as an outlet for the cooled solution. This reversibility of the flow of the cooled solution applies to all aspects involving a lumen.

[0017] In some embodiments, the path formed by the lumen extending from one end of the catheter to the other is a helix. For example, the lumen extending along the first flow section may form a single helix. A single helix is ​​defined herein as a single strand (e.g., a single lumen, wire, or semiconductor) shaped as a helix. The lumen may then be configured to return through the center of the catheter along the second flow section. In another embodiment, this condition may be reversed. Specifically, the lumen may extend through the center of the catheter along the first flow section. The lumen may then be configured to return along the helical second flow section. As previously mentioned, the particular geometry of the lumen within the catheter may serve to direct heat to and from particular regions of the catheter. Thus, the direction of heat may be controlled to create a particular heat distribution along the catheter. For example, a particular patient pathology or anatomical condition may benefit from a particular heat distribution. In a configuration in which the single helix contacts the inner surface of the catheter, one advantage is that the flow direction of the chilled solution through the lumen can be selected such that the fluid that has absorbed heat from the blood does not contact the inner surface of the catheter, thereby allowing the blood to be cooled rapidly. At least one advantage of a mechanical circulatory assist device (e.g., a blood pump) having a lumen extending along the length of the catheter and along the helix is ​​that such a pump can efficiently cool the blood to induce systemic hypothermia to treat the adverse effects of a cardiac episode, while also assisting the heart to counteract the adverse effects of the systemic hypothermia induction method.

[0018] In another embodiment, the lumen extends in both directions along the helix. The lumen extends along the first flow portion along the first helix, and the lumen extends along the second flow portion along the second helix. The first and second helix of the lumen are fluidly connected at the distal end of the catheter. In such an embodiment, the first and second helix may be offset at an angle along the circumference of the catheter to form a double helix. A double helix as defined herein comprises two helices of the same pitch and radius oriented 180 degrees from each other along the circumference of the catheter. In an embodiment in which the first and second helices are not offset at an angle along the circumference of the catheter, the first and second helices form a double-wide single helix. A double-wide single helix as defined herein comprises two single helices of the same pitch and radius that are in contact at each point along their length. In another embodiment, the first and second helices may be offset at an intermediate angle along the circumference of the catheter. The intermediate angle may be between 0 degrees and 180 degrees. For example, the first and second helices may be offset about 45 degrees along the circumference of the catheter. In another embodiment, the first and second helices may be offset about 90 degrees along the circumference of the catheter. In a particular embodiment, the first and second helices may be offset about 135 degrees along the circumference of the catheter. At least a portion of the helical element contacts the inner surface of the catheter, whether forming a double helix, a double-wide single helix, or any other configuration.

[0019] In some embodiments, the pitch of the double helix formed by the cooling element is between about 1 millimeter and about 10 millimeters. In further embodiments, the pitch of the double helix formed by the cooling element is between about 3 millimeters and about 8 millimeters. In another embodiment, the pitch of the double helix formed by the cooling element is between about 5 millimeters and about 6 millimeters. In a particular embodiment, the pitch of the double helix formed by the cooling element is about 5.5 millimeters. The pitch of the helix formed by the cooling element varies for each particular thermal and heat transfer profile established along the catheter.

[0020] In some embodiments, the double helix formed by the cooling element covers between about 30 percent and about 90 percent of the inner surface of the catheter. In other embodiments, the double helix formed by the cooling element covers between about 40 percent and about 80 percent of the inner surface of the catheter. In certain embodiments, the double helix formed by the cooling element covers between about 50 percent and about 70 percent of the inner surface of the catheter. In some embodiments, the double helix formed by the cooling element covers about 60 percent of the inner surface of the catheter. Blood pump embodiments having a larger inner surface area covered by the cooling element allow for more rapid cooling of the blood while still assisting the heart to address the adverse effects of systemic hypothermia induction.

[0021] In an embodiment having a lumen configured in a double helix, a first single helix extending along the first flow section and a second single helix extending along the second flow section are fluidly connected at the distal end of the catheter. Specifically, the lumen first extends along the first helix while extending along the first flow section. The lumen may then extend along the second helix while extending along the second flow section. After the lumen extends along the first flow section, the lumen extends along the circumferential length of the catheter at a fixed longitudinal point. The lumen may extend along the circumferential length of the catheter but may be in contact with the inner surface of the catheter. In a double helix configuration, the lumen extends along one-half of the circumference of the catheter at a fixed longitudinal point such that the first and second helices are offset at an angle of 180 degrees along the circumference of the catheter. At least one advantage of embodiments having a lumen configured in the shape of a double helix is ​​that by varying the pitch of the double helix, different cooling rates and different thermal profiles can be achieved along the length of the catheter.

[0022] In another embodiment, the lumen forms a double-wide single helix, which includes two single helices of the same pitch and the same radius, as defined above, that are in contact at each point along their length. In such an embodiment, the first single helix and the second single helix are fluidly connected. The first single helix, whose lumen extends along the first flow section, and the second single helix, whose lumen extends along the second flow section, together form a double-wide single helix. Specifically, the lumen extends along the first flow section while extending along the first helix. The lumen may then extend along the second flow section while extending along the second helix. After the lumen extends along the first flow section, the lumen extends along the circumferential length of the catheter at a fixed longitudinal point. In the double-wide, single-helix configuration, the lumen extends around the entire circumference of the catheter at a fixed longitudinal point such that the first and second helices are offset at an angle of 0 degrees around the circumference of the catheter. The pitch of the double-wide, single-helix may be tuned to obtain a particular thermal profile along the catheter.

[0023] In some embodiments, a chilled solution is infused into the lumen to cool the blood. The chilled solution may include a crystalloid solution. The crystalloid solution may be normal saline (a solution containing 9 grams of sodium chloride per liter of solution), lactated Ringer's solution, 1 / 3 NS 2 / 3D5, or glucose. Generally, a solution with the highest heat capacity is selected so that such a solution can most rapidly cool the blood without experiencing an increase in temperature, which allows the solution to maintain contact with the inner surface of the catheter along both lengths of the catheter. Thus, a blood pump having a lumen configured to receive a chilled solution can rapidly cool the blood, treating the adverse effects of a cardiac episode while also reducing the workload of the heart to provide assistance from the adverse effects of a systemic hypothermia induction procedure.

[0024] As an alternative to a cooling element configured as a lumen that delivers chilled solution along the length of the catheter, in some embodiments the cooling element is a Peltier element. The Peltier element may be embedded within the wall of the catheter or fixed along the exterior or interior surface of the catheter. In another embodiment, the Peltier element is embedded within the pump housing or other blood contacting component of the blood pump system. The Peltier element may be fused to the catheter, pump housing, or other blood contacting component of the blood pump system. In another embodiment, the Peltier element may be attached with an adhesive to the catheter, pump housing, or other blood contacting component of the blood pump system. In general, the Peltier element may be configured to direct heat from any combination of the catheter, pump housing, or other components of the blood pump system. The Peltier element drives the heat transfer between two semiconductor materials with different properties. For example, the electron densities of the two semiconductor materials may differ (e.g., one material may be an n-type semiconductor and the other material may be a p-type semiconductor). The Peltier element may be configured in a variety of geometric shapes. In particular, the Peltier element includes two semiconductor materials that form a junction that may be arranged in a variety of different configurations to direct heat flow in a desired direction. In general, the junctions may be located at any suitable points along the length of the catheter to achieve a desired heat distribution and rate of heat exchange along the length of the catheter. For example, the semiconductor material may be oriented to direct heat flow radially or oriented to direct heat flow longitudinally along the length of the catheter. The semiconductor material may further be arranged in any configuration that allows for the delivery of electrical current to the junctions formed by the semiconductor material. In some embodiments, the power source that delivers electrical current to the Peltier element is the same as the power source that powers the pump. In other embodiments, the power source that delivers electrical current to the Peltier element is different from the power source that powers the pump.Delivery of electrical current to the junction of the semiconductor material causes cooling by the Peltier effect, where cooling occurs when a voltage is applied to a junction comprising a first semiconductor material and a second semiconductor material, the junction being two semiconductor materials with different electron densities (e.g., an n-type semiconductor and a p-type semiconductor). Application of the Peltier effect causes the semiconductor material in contact with the inner surface of the catheter to decrease in temperature and act as a heat sink that cools blood in contact with the outer surface of the catheter to a systemic temperature. In some embodiments, the junction is located within the surface of the catheter toward the distal end of the catheter. In other embodiments, the junction may be configured within the wall of the catheter toward the proximal end of the conductor.

[0025] The first semiconducting material may be configured to extend twice along the length of the catheter. The first length of the catheter along which the semiconducting conductive material extends is generally equal to the second length of the catheter along which the semiconducting material extends. The first length of the catheter along which the semiconducting material extends may be from the proximal end of the catheter to the distal end of the catheter. The second length of the catheter along which the semiconducting material extends may be from the distal end of the catheter to the proximal end of the catheter. The first length of the catheter along which the semiconducting material extends may be three-quarters of the length of the catheter from the proximal end of the catheter to the distal end of the catheter, and the second length of the catheter along which the semiconducting material extends may be three-quarters of the length of the catheter from the distal end of the catheter to the proximal end of the catheter. At least one advantage of the Peltier element embodiment is that various semiconducting materials can be selected and incorporated to create a specific heat exchange rate and a specific heat distribution along the catheter. Thus, the incorporation of Peltier elements into a blood pump provides cardiac assist to overcome the adverse effects of systemic hypothermia induction techniques while also allowing the induction of systemic hypothermia to treat the adverse effects of a cardiac episode.

[0026] In embodiments having a Peltier element as the cooling element, the current delivered to the junction of the semiconductor material of the Peltier element may range from about 0.01 amps to about 3 amps. In some embodiments, a current of about 0.1 amps to about 2 amps is delivered to the junction of the semiconductor material of the Peltier element. In further embodiments, a current of about 0.5 amps to 1.5 amps is delivered to the junction of the semiconductor material of the Peltier element. In certain embodiments, a current of about 1 amp is delivered to the junction of the semiconductor material of the Peltier element. The specific current flowing through the wires of the Peltier element can be adjusted to create a specific potential difference at the junction of the semiconductor material, allowing for a specific heat distribution and blood cooling rate along the catheter.

[0027] According to some aspects of the disclosure, a method for treating the effects of a cardiac episode in a patient includes first introducing a mechanical circulatory assist device into the patient's vascular system. The mechanical circulatory assist system may be a blood pump. The blood pump includes a fluid lumen or a cooling element, such as a Peltier element, disposed within a catheter. After introducing the blood pump into the patient's vascular system, the practitioner performing the method places the catheter within the vascular system such that the exterior surface of the catheter is in contact with blood flowing through the vascular system. The practitioner then operates the blood pump to circulate blood within the patient. While operating the blood pump, the practitioner activates the cooling element. As previously described, the cooling element functions as a heat exchanger by cooling the interior surface of the catheter. The interior surface of the catheter then cools the exterior surface of the catheter, which in turn cools the patient's blood. This cooling is performed for a selected period of time to ensure that the exterior surface of the catheter reaches a selected temperature. The temperature of the exterior surface of the catheter is selected such that blood in contact with the exterior surface of the catheter is cooled to a certain systemic temperature. The temperature to which the exterior surface is cooled may be equal to or lower than the systemic temperature. Specifically, the blood is cooled to a selected systemic temperature to treat the effects of the cardiac episode. In some embodiments, the cardiac episode may be a myocardial infarction, and in some embodiments, the effect of a myocardial infarction is myocardial scarring.

[0028] In some embodiments, a blood pump is inserted into the left side of the patient's heart such that the system assists in unloading the patient's left ventricle. In other embodiments of the method, a blood pump is inserted into the right side of the patient's heart such that the system assists in unloading the patient's right ventricle.

[0029] In certain embodiments, a first blood pump is introduced to one side of the patient's heart and a second blood pump is introduced to the other side of the patient's heart. In some embodiments, a first blood pump is introduced to the right side of the patient's heart and a second blood pump is introduced to the left side of the patient's heart. In another embodiment, a first blood pump is introduced to the left side of the patient's heart and a second blood pump is introduced to the right side of the patient's heart. Such embodiments include simultaneously cooling the blood and unloading both sides of the patient's heart. Simultaneously cooling the blood and unloading both sides of the heart may allow the practitioner to cool the heart more quickly than cooling one side and simultaneously assist the heart to prevent undesirable effects of systemic hypothermia induction.

[0030] In another embodiment, a method for treating the effects of a cardiac episode in a patient includes first introducing into the patient's vascular system a mechanical circulatory assist device including a lumen configured within a catheter. The mechanical circulatory assist device of the method may be a blood pump. After introducing the blood pump into the vascular system, the practitioner performing the method of the aspect positions the catheter within the patient's vascular system such that the exterior surface of the catheter is in contact with blood flowing within the vascular system. Once the blood pump is properly positioned, the practitioner activates the blood pump, and while the system is operating, the practitioner injects a cooled solution into the lumen. Injecting the cooled solution into the lumen cools the exterior surface of the catheter for a period of time to a temperature of the exterior surface of the catheter selected such that circulating blood in contact with the exterior surface of the catheter is cooled to a systemic temperature. The temperature to which the exterior surface of the catheter is cooled may be equal to or below the systemic temperature. The systemic temperature is selected to reduce or prevent the effects of the cardiac episode. In some embodiments, the cardiac episode is a myocardial infarction, and the effect of the myocardial infarction is myocardial scarring. Such an embodiment provides the advantage that a chilled solution inserted into the lumen can induce systemic hypothermia in the patient's blood to treat or prevent the adverse effects of a cardiac episode, while the pump circulates blood within the patient to prevent adverse side effects that may be caused by systemic hypothermia induction methods (e.g., by reducing the workload of the heart).

[0031] In another embodiment, a method for treating the effects of a cardiac episode in a patient includes first introducing a mechanical circulatory assist device into the vasculature of the patient. The mechanical circulatory assist device may be a blood pump. The blood pump of the embodiment includes a Peltier element configured in a catheter that includes a junction of two semiconductor materials having different electron densities. After introducing the blood pump into the vasculature, the practitioner performing the method of the embodiment positions the catheter in the vasculature of the patient such that the outer surface of the catheter is in contact with the blood flowing in the vasculature. Once the blood pump is properly positioned, the practitioner activates the blood pump, and while the blood pump is activated, the practitioner applies an electric current to the first wire. The cooling semiconductor material cools the outer surface of the catheter by the Peltier effect, where an electric current flowing between the junction of the two semiconductor materials allows for the removal of heat from one of the semiconductor materials. This cooling occurs over a period of time until a temperature of the outer surface of the catheter selected such that circulating blood in contact with the outer surface of the catheter is cooled to a systemic temperature is achieved. The systemic temperature is selected to reduce or prevent the effects of the cardiac episode. In some embodiments, the cardiac episode is a myocardial infarction, and the effect of the myocardial infarction is myocardial scarring. Thus, a pump configured with a Peltier element can provide cardiac assistance to prevent the adverse effects of systemic hypothermia induction procedures while still inducing systemic hypothermia to treat or prevent the adverse effects of a cardiac episode.

[0032] In certain embodiments of the method, a first blood pump including a Peltier element is introduced to one side of the patient's heart and a second blood pump including a Peltier element is introduced to the other side of the patient's heart. In some embodiments, a first blood pump including a Peltier element is introduced to the right side of the patient's heart and a second blood pump including a Peltier element is introduced to the left side of the patient's heart. In another embodiment, a first blood pump including a Peltier element is introduced to the left side of the patient's heart and a second blood pump including a Peltier element is introduced to the right side of the patient's heart. Such embodiments include cooling and unloading both sides of the patient's heart simultaneously. Unloading and cooling both sides of the heart simultaneously allows the practitioner to cool the blood in the heart more quickly, preventing the effects of a cardiac episode while simultaneously unloading the heart to prevent the adverse effects of a systemic hypothermia induction procedure. [Brief description of the drawings]

[0033] [Figure 1] An illustrative example of a mechanical circulatory assist system for the heart having a cooling element is shown, the components of which are shown in more detail in FIG. [Diagram 2] 1 shows an exemplary perspective view of a portion of a mechanical circulatory assist system for a heart having a cooling element. [Figure 3A] Illustrated example of a cross section of a double-width single helix is ​​shown. [Figure 3B] Illustrated example of a cross section of a double-width single helix is ​​shown. [Figure 3C] Illustrated example of a cross section of a double-width single helix is ​​shown. [Figure 4] 1 illustrates an exemplary method for treating a myocardial infarction while simultaneously unloading the heart. [Diagram 5] 1 illustrates an exemplary method for treating a myocardial infarction while simultaneously unloading the heart using a mechanical circulatory assist system configured with a lumen. [Figure 6] 1 illustrates an exemplary method for treating a myocardial infarction while simultaneously unloading the heart using a mechanical circulatory assist system configured with Peltier elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Detailed Description Certain exemplary aspects are described to provide an overall understanding of the systems, methods, and devices disclosed herein. Although the aspects and features described herein are specifically described for use in connection with pumps for the heart, it will be understood that the teachings may be adapted and applied to other pumps and other types of medical devices.

[0035] The systems, methods, and devices described herein provide a mechanical circulatory support system for the heart that is configured to reduce the load on the heart while simultaneously inducing hypothermia in a patient to cool the patient's blood to reduce or prevent the deleterious effects of a cardiac episode. Specifically, the systems, methods, and devices described herein provide a pump having a systemic cooling element along the length of the pump's catheter, the cooling element configured to induce hypothermia in the patient's heart to reduce or prevent scarring caused by a myocardial infarction.

[0036] FIG. 1 shows an illustrative example of a mechanical circulatory assist system for the heart or blood pump 100 having a cooling element, which allows the pump to simultaneously reduce the load on the heart while inducing hypothermia in the patient. The illustrative FIG. 1 shows a cooling element extending along a single helix that extends in one direction along the length of the catheter. As previously mentioned, a single helix as defined herein refers to a single strand shaped as a helix. The heart pump 100 further includes a rotor 102, a motor 104, a pump housing 106 having a distal end 108 and a proximal end 110, a cannula 112, a distal extension 114, a cooling element 116, and a catheter 118 having an inner surface 120, an outer surface 122, a distal end 124, and a proximal end 126. The heart pump 100 with the rotor 102, motor 104, and pump housing 106 is shown in more detail in FIG. 7. The cooling element 116 has a diameter 128, and the catheter 118 has a radius 130. The helix formed by the cooling element 116 has a pitch 132. The catheter 118 extends proximally from the proximal end 110 of the pump housing 106. The cooling element 116 is configured within the catheter 118. As shown in FIG. 1, the cooling element 116 extends along a length L1 of the catheter 118 before folding back on itself. However, the cooling element 116 may be configured to extend along the illustrated length L2 of the catheter 118, or along any other length of the catheter 118, such that systemic cooling of the patient's blood is achieved when the blood pump 100 is disposed within the heart or other portion of the vascular system. Thus, the cooling element 116 is configured to extend generally twice the length of the catheter 118. The cooling element 116 extends along a first length from the proximal end 126 of the catheter 118 to the distal end 124 of the catheter 118, and a second length from the distal end 124 of the catheter 118 to the proximal end 126 of the catheter 118. At least one advantage of incorporating the cooling element 116 within the catheter 118 is that the system can induce hypothermia within a patient's heart to prevent or reduce the deleterious effects of a cardiac episode while simultaneously reducing the load on the heart to prevent deleterious effects commonly encountered when inducing hypothermia in a patient's heart.A cardiac episode requiring the use of such a pump may be a myocardial infarction or heart attack, and the effect of such an episode may be myocardial scarring. Lowering the temperature of a patient's blood via induced hypothermia may generally slow one or more biological processes responsible for the formation of myocardial scarring, thereby helping to prevent long-term damage to the heart after a patient suffers a cardiac episode.

[0037] The cooling element 116 may be configured in the catheter in a variety of different geometries. As previously mentioned, the cooling element 116 may extend along any suitable length of the catheter 118 before folding back on itself. Two such exemplary lengths L1 and L2 are shown in FIG. 1. The cooling element 116 may extend along any other suitable length of the catheter 118. In addition, the cooling element 116 may be oriented in a different geometry along each of the two lengths of the catheter 118 along which the cooling element 116 extends. For example, in the exemplary FIG. 1, the cooling element 116 extends in a straight line from the proximal end 126 of the catheter 118 to the distal end 124 of the catheter 118. The cooling element 116 may extend along the length L1 once and then fold back to extend along a spiral from the distal end 124 of the catheter 118 to the proximal end 126 of the catheter 118. In FIG. 1 , the helix by which the cooling element 116 extends from the distal end 124 of the catheter 118 to the proximal end 126 of the catheter 118 may be confined to the inner surface 120 of the catheter 118. In embodiments in which the cooling element 116 is luminal, a chilled solution is injected into the cooling element 116. As previously mentioned, for a given geometry of the cooling element 116 that includes a lumen, the direction of flow of the chilled solution within the lumen is reversible. In such embodiments, the chilled fluid may be injected into either length of the element 116 such that the chilled fluid first extends along a straight portion of the element 116 and then extends back along the helical portion of the element 116 toward the proximal end 126 of the catheter 118, or the chilled fluid first extends along the helical portion of the element 116 and then extends back along the straight portion of the element 116 toward the proximal end 126 of the catheter 118.

[0038] The pitch 132 of the helix along which the cooling element 116 extends from the distal end 124 of the catheter 118 to the proximal end 126 of the catheter 118 may vary between embodiments. For example, the pitch 132 of the helix along which the cooling element 116 extends may be from about 1 millimeter to about 21 millimeters. In some embodiments, the pitch 132 of the helix along which the cooling element 116 extends may be from about 3 millimeters to about 19 millimeters. In other embodiments, the pitch 132 of the helix along which the cooling element 116 extends may be from about 5 millimeters to about 17 millimeters. In certain embodiments, the pitch 132 of the helix along which the cooling element 116 extends may be from about 7 millimeters to about 15 millimeters. In further embodiments, the pitch 132 of the helix along which the cooling element 116 extends may be from about 9 millimeters to about 13 millimeters. In other embodiments, the pitch 132 of the helix along which the cooling element 116 extends may be about 11 millimeters. At least one advantage of the variable pitch 132 of the helix formed by the cooling element 116 is that the particular geometry of the cooling element can be selected to obtain a desired internal surface area covered by the cooling element 116.

[0039] Similarly, diameter 128 may be selected to achieve a desired covered interior surface area. For example, diameter 128 may be from about 0.5 millimeters to about 7.5 millimeters. In another embodiment, diameter 128 may be from about 1 millimeter to about 7 millimeters. In a further embodiment, diameter 128 may be from about 1.5 millimeters to about 6.5 millimeters. In a particular embodiment, diameter 128 may be from about 2 millimeters to about 6 millimeters. In another embodiment, diameter 128 may be from about 2.5 millimeters to about 5.5 millimeters. In another embodiment, diameter 128 may be from about 3 millimeters to about 5 millimeters. In a further embodiment, diameter 128 may be about 4 millimeters.

[0040] The distance between the straight portion of the cooling element 116 and the inner surface 120 of the catheter 118 can also be adjusted to provide a particular temperature profile along the length of the device. For example, the straight portion of the cooling element may extend to the center of the catheter 118. In another embodiment, the straight portion of the cooling element may extend along the length of the catheter 118, midway between the center of the catheter 118 and the inner surface 120 of the catheter 118. The smaller the distance between the straight portion of the cooling element 116 and the inner surface 120 of the catheter 118, the lower the temperature of the outer surface 122 of the catheter 118. Conversely, the greater the distance between the straight portion of the cooling element 116 and the inner surface 120 of the catheter 118, the higher the temperature of the outer surface 122 of the catheter 118.

[0041] In some embodiments, the cooling element 116 extends along a first helix that extends from the proximal end 126 of the catheter 118 to the distal end 124 of the catheter 118. The first helix may extend along a desired length along the catheter 118 once and then turn back on itself to form a second helix that extends from the distal end 124 of the catheter 118 to the proximal end 126 of the catheter 118. These two helices may be circumferentially offset from one another by an angle ranging from 0 degrees to 180 degrees.

[0042] An embodiment in which the angle between the two helices is 180 degrees defines a cooling element configured as a double helix. In such an embodiment, the first helix may extend along a first length along the catheter from the proximal end 126 of the catheter 118 to the distal end 124 of the catheter 118, and then extend along a semi-circumference of the catheter 118 at a given longitudinal point along the length of the catheter 118. After extending along this semi-circumference, the second helix along which the cooling element 116 extends may extend along a second length of the catheter 118 from the distal end 124 of the catheter 118 to the proximal end 126 of the catheter 118. The double helix formed by the cooling element 116 may have a variable pitch. For example, the pitch of the double helix along which the cooling element 116 extends may be from about 1 millimeter to about 21 millimeters. In some embodiments, the pitch of the double helix along which the cooling element 116 extends may be from about 3 millimeters to about 19 millimeters. In another embodiment, the pitch of the double helix along which the cooling element 116 extends may be between about 5 and about 17 millimeters. In a particular embodiment, the pitch of the double helix along which the cooling element 116 extends may be between about 7 millimeters and about 15 millimeters. In a further embodiment, the pitch of the double helix along which the cooling element 116 extends may be between about 9 millimeters and about 13 millimeters. In another embodiment, the pitch of the double helix along which the cooling element extends may be about 11 millimeters. As previously mentioned, an embodiment in which the angle between the two helices is 0 degrees defines a cooling element configured as a double-wide single helix. A double-wide single helix as defined above includes two single helices of the same pitch and the same radius that meet at each point along their lengths.

[0043] In some embodiments, the catheter radius 130 may correspond to the radius of the helix formed by the cooling element 116. In such embodiments, the cooling element 116 is confined to the inner surface 120 of the catheter 118. In another embodiment, the catheter radius 130 may be greater than one or both of the radii of the helix formed by the cooling element 116. For example, the first helix formed by the cooling element 116 may be confined to the inner surface 120 of the catheter 118, while the second helix may have a radius of about ⅙ to about ⅔ of the catheter radius 130. In another embodiment, the radius of the second helix is ​​about ⅓ to about ⅔ of the catheter radius 130. In a further embodiment, the second helix formed by the element 116 may have a radius of about ½ of the catheter radius 130. In embodiments where the angle of offset between the first and second helix is ​​not 180 degrees, the two helices may form a single double-wide helix. Such a configuration is further described below in connection with FIG. 3.

[0044] FIG. 2 is an exemplary perspective view of a portion of a mechanical circulatory assist system or blood pump 200 for a heart having a cooling element 210 configured as a double helix. The exemplary blood pump system 200 includes a catheter 202 having an inner surface 204, an outer surface 206, and a radius 208, and a cooling element 210. In FIG. 2, the cooling element 210 is arranged as a double helix including two single helices having a pitch 212. The double helices of the exemplary cooling element 210 shown in FIG. 2 have a radius equal to the radius 208 of the catheter. Thus, the cooling element 210 shown in FIG. 2 is confined to the inner surface 204 of the catheter 202. In some embodiments, the radius 208 of the catheter may be greater than one or both of the radii of the helices formed by the cooling element 210. For example, the first spiral formed by the cooling element 210 may have a radius equivalent to the catheter radius 208 such that it is confined to the inner surface 204 of the catheter 202 while the second spiral may have a radius of about 1 / 6 to 5 / 6 of the catheter radius 208. In another embodiment, the radius of the second spiral is about 1 / 3 to 2 / 3 of the catheter radius 208. In a further embodiment, the second spiral formed by the element 210 may have a radius of about 1 / 2 of the catheter radius 208. In another embodiment, the first spiral and the second spiral both have radii less than the catheter radius 208. For example, in some embodiments, the first and second spirals have radii of about 1 / 6 to about 5 / 6 of the catheter radius 208. In another embodiment, the first and second spirals have radii of about 1 / 3 to about 2 / 3 of the catheter radius 208. In certain embodiments, the first and second helices have a radius that is about 1 / 3 to about 2 / 3 of the radius 208 of the catheter.

[0045] As discussed above in connection with FIG. 1, the first and second helices formed by the elements 210 may be circumferentially offset from one another by an angle ranging from 0 degrees to 180 degrees. Thus, the first and second helices formed by the elements 210 may be configured as a double helix or as a double-width single helix. In the exemplary embodiment of FIG. 2, the first and second helices are offset by an angle of 180 degrees to form a double helix, as defined above. As described below in connection with FIG. 3, the two helices may be offset by an angle of 0 degrees to form a double-width single helix along the length of the catheter 202.

[0046] In some embodiments, the cooling element 210 forms only one spiral along the length of the catheter 202. For example, the cooling element 210 may extend in one direction through the center of the catheter 202 and in the other direction along the inner surface 204 of the catheter 202 in the shape of a spiral. The particular geometry of the cooling element 210 within the catheter 202 can be tailored to obtain a particular temperature profile along the length of the catheter 202.

[0047] 3A, 3B, and 3C show three illustrative examples of cross-sections of a catheter including a cooling element for use in a mechanical circulatory assist system or blood pump for the heart. Although FIGS. 3A, 3B, and 3C illustrate cross-sections of a catheter including a lumen configured as a cooling element, as previously described, the cooling element may be a Peltier element. FIG. 3A shows an exemplary cross-section of a cooling element for use in a blood pump system 300 for the heart having a first lumen 302, a second lumen 304, a lumen channel 306, and a catheter 308. In FIG. 3A, the first lumen 302 and the second lumen 304 are contained within the lumen channel 306. The lumen channel 306 is contained within the catheter 308. In FIG. 3A, the first lumen 302 accommodates flow in a first direction from the proximal end of the catheter to the distal end of the catheter, and the second lumen 304 accommodates flow in a second direction from the distal end of the catheter to the proximal end of the catheter. FIG. 3B shows another exemplary cross-section of a cooling element for use in a blood pump 310 for a heart, having a first lumen 312, a second lumen 314, and a catheter 316. In FIG. 3B, the first lumen 312 accommodates flow in a first direction from the proximal end of the catheter to the distal end of the catheter, and the second lumen 314 accommodates flow in a second direction from the distal end of the catheter to the proximal end of the catheter. FIG. 3C shows a third exemplary cross-section of a cooling element for use in a blood pump 320 for a heart, having a first lumen portion 322, a second lumen portion 324, a lumen channel 326, and a catheter 328. In FIG. 3C, the first lumen portion 322 and the second lumen portion 324 are contained within the lumen channel 326. Specifically, lumen channel 326 is divided into two portions, a first lumen portion 322 that includes a first lumen and a second lumen portion 324 that includes a second lumen. First lumen portion 322 and second lumen portion 324 may be oriented in various configurations within lumen channel 326. For example, as shown in FIG. 3C, first lumen portion 322 and second lumen portion 324 may each include half of lumen channel 326. In another embodiment, first lumen portion 322 may include a larger portion of lumen channel 326 than second lumen portion 324.In another embodiment, the first lumen portion 322 may include a smaller portion of the lumen channel 326 than the second lumen portion 324. The lumen channel 326 is contained within a catheter 328. In FIG. 3C, the first lumen portion 322 accommodates flow in a first direction from the proximal end of the catheter to the distal end of the catheter 328, and the second lumen portion 324 accommodates flow in a second direction from the distal end of the catheter to the proximal end of the catheter 328. In configurations having Peltier elements as cooling elements, the semiconductors of the Peltier elements may be similarly oriented in various configurations and relative shapes and sizes. For example, the first semiconductor material of the Peltier element may be configured to conform to the shape of the inner surface of the catheter and contact the inner surface of the catheter, while the second semiconductor material may be cylindrical and extend along the center of the catheter. Additionally, the first semiconductor material may be embedded within the wall of the catheter. In some embodiments, the first semiconductor material may have a surface area that is greater than the surface area of ​​the second semiconductor material. In another embodiment, the first semiconductor material may have the same surface area as the second semiconductor material. In a particular embodiment, the first semiconductor material may have a smaller surface area than the second semiconductor material.

[0048] FIG. 4 illustrates an exemplary method 400 for treating a myocardial infarction while simultaneously unloading the heart. Method 400 first includes step 402 of introducing a mechanical circulatory assist system to the left side of the patient's heart. The mechanical circulatory assist system may be a blood pump. The pump of method 400 includes a cooling element configured within a catheter. Such cooling element is configured to receive either a chilled solution or an electric current, and the cooling element is configured to contact an inner surface of the catheter such that blood in contact with the outer surface of the catheter is cooled. The practitioner performing method 400 then performs step 404, which includes activating the pump using an internal motor. After the pump is activated, the practitioner then performs step 406, which includes activating the cooling element to cool the blood in contact with the outer surface of the catheter. In step 406, the blood is cooled for a period of time such that the blood reaches a systemic temperature. For example, the blood may be systemically cooled for a period of time of about 5 minutes to about 20 minutes. In another embodiment, the period of time is about 7.5 minutes to about 17.5 minutes. In a further embodiment, the period of time is about 10 minutes to about 15 minutes. In some embodiments, the period during which the blood is cooled to whole body temperature is about 12.5 minutes. The whole body temperature is selected to reduce or prevent the effects of a cardiac episode. In some embodiments, the cardiac episode being treated or prevented is myocardial infarction, and in some embodiments, the effect of myocardial infarction being treated or prevented is myocardial scarring. Cooling the blood circulating through the heart slows the biological processes that cause myocardial scarring, which reduces and prevents scarring of the heart in patients following myocardial infarction. The included cooling element induces hypothermia in the patient, while the assistance provided by the blood pump helps to reduce the workload of the heart, preventing or reducing the negative side effects of hypothermia induction methods, including induced arrhythmias.

[0049] FIG. 5 illustrates an exemplary method 500 for treating a myocardial infarction while simultaneously unloading the heart using a mechanical circulatory support system configured with a lumen. The mechanical circulatory support system may be a blood pump. In another embodiment, the mechanical circulatory support system may be an intra-aortic balloon pump, a left ventricular assist system, or a right ventricular assist system. As discussed above, the lumen of the mechanical circulatory support system of the method may be configured in various geometric shapes. For example, as shown in FIG. 1, the lumen may extend along a helix in one direction along the length of the catheter. In another embodiment, the lumen may form a double helix as shown in FIG. 2. The method 500 first includes a step 502 of introducing a blood pump to the left side of the patient's heart. The pump of the method 500 includes a lumen configured to receive a cooled fluid. As discussed above, the cooled solution may include a crystalloid solution. The crystalloid solution may be normal saline (a solution containing 9 grams of sodium chloride per liter of solution), lactated Ringer's solution, 1 / 3 NS 2 / 3D5, or glucose. Generally, a solution with the greatest heat capacity is selected so that such a solution can most rapidly cool the blood without experiencing an increase in temperature, thereby allowing the solution to maintain contact with the inner surface of the catheter along both lengths of the catheter. For any geometry, at least a portion of the lumen contacts the inner surface of the catheter, and the lumen is configured to cool the blood in contact with the outer surface of the catheter. The practitioner performing method 500 operates the pump using the built-in motor in step 504. While operating the pump, the practitioner injects cooled solution into the lumen in step 506 to cool the blood in contact with the outer surface of the catheter. In step 506, the blood is cooled for a period of time such that the blood reaches a systemic temperature. The systemic temperature is selected to reduce or prevent the effects of the cardiac episode. As previously mentioned, the temperature of the cooled solution is selected to be cold enough that the blood reaches a systemic temperature and is sufficiently cold to delay biological processes that are responsible for causing adverse effects to the patient after the patient suffers a cardiac episode. The cardiac episode may be a myocardial infarction, and the effect of the myocardial infarction may be scarring.By simultaneously cooling and unloading the heart, the cooling element allows for the induction of hypothermia while the blood pump prevents the deleterious effects of hypothermia induction techniques.

[0050] FIG. 6 illustrates an exemplary method 600 for treating a myocardial infarction while simultaneously unloading the heart using a mechanical circulatory assist system configured with a Peltier element. The mechanical circulatory assist system may be a blood pump. The method 600 includes the step 602 of introducing a blood pump to the left side of the patient's heart. The pump of the method 600 includes a Peltier element. The Peltier element transfers heat between two semiconductor materials having different properties. For example, the electron densities of the two semiconductor materials may be different. The Peltier element may be configured in a variety of geometric shapes. In particular, the Peltier element includes two semiconductor materials that form a junction that may be arranged in a variety of different configurations to direct the flow of heat in a desired direction and to a desired portion of the device. For example, the semiconductor materials may be oriented such that the flow of heat is radial, or the semiconductor materials may be oriented such that the flow of heat is longitudinal along the length of the catheter. Furthermore, the semiconductor materials may be arranged in any configuration that allows for the delivery of an electric current to the junction formed by the semiconductor materials. The junction of the two semiconductor materials having different electron densities may be located at any suitable point along the length of the catheter to establish a specific heat distribution along the length of the catheter. In some embodiments, the junction of the two semiconductor materials having different electron densities is located at the distal end of the catheter. In another embodiment, the junction of the two semiconductor materials having different electron densities is located at the proximal end of the catheter. One of the semiconductor materials is in contact with the inner surface of the catheter so as to be configured to cool blood in contact with the outer surface of the catheter. After introducing the pump, the practitioner then operates the pump using the built-in motor in step 604. While operating the pump, in step 606, a current is passed through the first wire to the junction of the semiconductor materials of the Peltier element to cool blood in contact with the outer surface of the catheter. The current delivered to the junction of the semiconductor materials of the Peltier element may range from about 0.01 amps to about 3 amps. In some embodiments, a current of about 0.1 amps to about 2 amps is delivered to the junction of the semiconductor materials of the Peltier element. In a further embodiment, a current of about 0.5 amps to 1.5 amps is delivered to the junction of the semiconductor material of the Peltier element.In certain embodiments, a current of about 1 ampere is delivered to the semiconductor material junction of the Peltier element. The particular current through the wires of the Peltier element can be adjusted to produce a particular potential difference at the semiconductor material junction, allowing for a particular heat distribution along the catheter and cooling rate of the blood. The blood is cooled for a period of time such that the blood reaches a systemic temperature. For example, the blood may be systemically cooled for a period of about 5 minutes to about 20 minutes. In another embodiment, the period of time is about 7.5 minutes to about 17.5 minutes. In further embodiments, the period of time is about 10 minutes to about 15 minutes. In some embodiments, the period of time during which the blood is cooled to the systemic temperature is about 12.5 minutes. The systemic temperature is selected to reduce or prevent the effects of the cardiac episode. The cardiac episode may be a myocardial infarction, and the effect of the myocardial infarction being treated may be myocardial scarring.

[0051] The foregoing is merely illustrative of the principles of the disclosure, and the device may be practiced in other than the described aspects presented for purposes of illustration and not limitation. It is to be understood that the device disclosed herein is shown for use in a pump, but may also be applied to other devices. Modifications and variations will occur to those skilled in the art after reviewing this disclosure. The features disclosed may be implemented in any combination and subcombination (including multiple subordinate combinations and subcombinations) with one or more other features described herein. The various features described or illustrated above, including any components thereof, may be combined or integrated with other systems. Additionally, certain features may be omitted or not implemented.

[0052] Those skilled in the art will recognize examples of changes, substitutions, and alterations that can be made without departing from the scope of the information disclosed herein. All documents cited herein are incorporated by reference in their entirety and made a part of this application.

Claims

1. a pump having a distal end and a proximal end, the pump including a rotor, the rotor having at least one blade; a pump housing surrounding the at least one blade of the rotor; a catheter having a distal end, a proximal end, an inner surface, and an outer surface, the catheter extending proximally relative to the pump housing, the outer surface configured to contact blood when positioned within a patient's vascular system; 1. A mechanical circulatory assist system for a heart, comprising: the outer surface of the catheter includes a heat transfer surface configured to cool blood in contact with the outer surface. A mechanical circulatory support system for the heart.

2. The mechanical circulatory assist system of claim 1 , wherein the heat transfer surface is configured to cool an exterior surface of the catheter.

3. 10. The mechanical circulatory assist system of claim 1, further comprising a cooling element.

4. The mechanical circulatory assist system of claim 3, wherein the cooling element extends within the catheter.

5. 4. The mechanical circulatory assist system of claim 3, wherein the cooling element is configured to cool an interior surface of the catheter.

6. 6. The mechanical circulatory assist system of claim 5, wherein cooling the inner surface is configured to conduct thermal energy away from an outer surface of the catheter to cool said outer surface.

7. The mechanical circulatory assist system of claim 6, wherein the cooling element is configured to cool an outer surface of the catheter.

8. The mechanical circulatory assist system of claim 3 , wherein the cooling element is formed as a lumen.

9. 10. The mechanical circulatory assist system of claim 8, wherein the lumen is configured to extend twice along the length of the catheter.

10. 10. The mechanical circulatory assist system of claim 8, wherein the lumen has a first proximal opening configured as an inlet for the cooled solution and a second proximal opening serving as an outlet for the cooled solution.

11. 11. The mechanical circulatory assist system of claim 10, wherein the first flow portion along which the lumen extends is from the proximal end to the distal end and the second flow portion along which the lumen extends is from the distal end to the proximal end.

12. 12. The mechanical circulatory assist system of claim 11, wherein the first flow portion forms a first single helix and the second flow portion forms a second single helix.

13. 13. The mechanical circulatory assist system of claim 12, wherein the first single helix and the second single helix are offset from each other by one-half a circumference of the catheter, the first and second single helices forming a double helix.

14. 13. The mechanical circulatory assist system of claim 12, wherein a first single helix is ​​disposed adjacent to a second single helix to form a single helix having two lumens.

15. 4. The mechanical circulatory assist system of claim 3, wherein the cooling element is a Peltier element disposed along the length of the catheter.

16. 4. The mechanical circulatory assist system of claim 3, wherein the cooling element cools blood in contact with the exterior surface of the catheter to a systemic temperature.

17. The mechanical circulatory assist system of claim 16, wherein the whole body temperature is about 32 to about 33 degrees Celsius.

18. The mechanical circulatory assist system of claim 13, wherein the pitch of the double helix formed by the cooling element is between about 0.1 millimeters and about 10 millimeters.

19. 14. The mechanical circulatory assist system of claim 13, wherein a surface area of ​​the double helix configured to contact an inner surface of the catheter covers at least 60 percent of the surface area of ​​the catheter.

20. The mechanical circulatory assist system of claim 10 , wherein the cooled solution comprises a crystalloid solution.

21. 21. The mechanical circulatory support system of claim 20, wherein the crystalloid fluid is normal saline.

22. introducing a mechanical circulatory assist device, the mechanical circulatory assist device including a cooling element within a catheter, into the vascular system of a patient; placing the catheter within the vascular system such that an exterior surface of the catheter is in contact with blood flowing within the vascular system; activating a mechanical circulatory assist device to circulate blood within the patient; and activating the cooling element to cool the exterior surface of the catheter for a period of time to a temperature selected to cool the circulating blood in contact with the exterior surface of the catheter to a systemic temperature while the mechanical circulatory assist device is in operation.

46. ​​A method for treating the effects of a cardiac episode in a patient comprising:

23. 23. The method of claim 22, wherein the temperature is selected to reduce or prevent the effects of a cardiac episode.

24. 24. The method of claim 23, wherein the cardiac episode is a myocardial infarction.

25. 24. The method of claim 23, wherein the effect of the cardiac episode is scarring.

26. 23. The method of claim 22, wherein the whole body temperature is less than 37 degrees Fahrenheit.

27. 23. The method of claim 22, wherein the whole body temperature is about 32 to about 33 degrees Celsius.

28. 23. The method of claim 22, wherein the blood is cooled for about 10 to about 15 minutes.

29. 23. The method of claim 22, wherein the mechanical circulatory assist device is inserted into the left side of the patient's heart.

30. 30. The method of claim 29, further comprising introducing a second mechanical circulatory assist system to the right side of the patient's heart.

31. 31. The method of claim 30, wherein a mechanical circulatory assist system is introduced to the left side of the patient's heart before a second mechanical circulatory assist system is introduced to the right side of the patient's heart.

32. 31. The method of claim 30, wherein the mechanical circulatory assist system is introduced to the left side of the patient's heart after a second mechanical circulatory assist system is introduced to the right side of the patient's heart.

33. 31. The method of claim 30, further comprising the steps of unloading and cooling the right side of the heart while cooling and unloading the left side of the heart.

34. 23. The method of claim 22, wherein the mechanical circulatory assist device is configured to be powered by an internal motor.

35. 23. The method of claim 22, wherein the catheter further comprises a distal end, a proximal end, an inner surface, and an outer surface.

36. 36. The method of claim 35, wherein the cooling element is configured to extend from the proximal end to the distal end of the catheter and back to the proximal end.

37. 36. The method of claim 35, wherein the cooling element contacts an inner surface of the catheter.

38. 23. The method of claim 22, wherein the cooling element is a lumen configured to receive the cooled solution.

39. 40. The method of claim 38, wherein the lumen has a first proximal opening configured as an inlet for the cooled solution and a second proximal opening configured as an outlet for the cooled solution.

40. 40. The method of claim 38, wherein the lumen is configured to extend twice along the length of the catheter.

41. 23. The method of claim 22, wherein the cooling element is a Peltier element.

42. 36. The method of claim 35, wherein a first path along which the cooling element extends from a proximal end of the catheter to a distal end of the catheter forms a first spiral.

43. 43. The method of claim 42, wherein a second path along which the cooling element extends from the distal end of the catheter to the proximal end of the catheter forms a second spiral.

44. 44. The method of claim 43, wherein the first and second helices are fluidly connected at a distal end of the catheter.

45. 44. The method of claim 43, wherein the first spiral and the second spiral are offset at an angle around a circumference of the catheter at the distal end of the catheter.

46. 46. ​​The method of claim 45, wherein the angle of offset between the first helix and the second helix is ​​0 degrees.

47. 46. ​​The method of claim 45, wherein the angle of offset between the first helix and the second helix is ​​180 degrees, such that the first and second helix form a double helix.

48. 48. The method of claim 47, wherein the pitch of the double helix formed by the cooling element is between about 1 millimeter and about 10 millimeters.

49. 48. The method of claim 47, wherein the double helix is ​​configured to contact an inner surface of the catheter and covers 60% of the area of ​​the catheter.

50. 40. The method of claim 39, wherein the cooled solution comprises a crystalloid solution.

51. 51. The method of claim 50, wherein the crystalloid solution is normal saline.

52. 42. The method of claim 41, wherein the Peltier element is configured to receive a current of about 0.1 amps to about 2 amps.

53. introducing into the patient's vascular system a mechanical circulatory assist system including a cooling element within a catheter, the cooling element being a lumen configured to receive a chilled solution; placing the catheter within the vascular system such that an exterior surface of the catheter is in contact with blood flowing within the vascular system; activating a mechanical circulatory assist system; and while the assist system is operating, injecting the cooled solution into the lumen to cool the exterior surface of the catheter to a temperature selected to cool the blood in contact with the exterior surface of the catheter to a systemic temperature for a period of time.

46. ​​A method for treating the effects of a cardiac episode in a patient comprising:

54. 54. The method of claim 53, wherein the selected temperature is selected to reduce or prevent the effects of a cardiac episode.

55. 55. The method of claim 54, wherein the cardiac episode is a myocardial infarction.

56. 55. The method of claim 54, wherein the effect of the cardiac episode is scarring.

57. 54. The method of claim 53, wherein the whole body temperature is less than 37 degrees Fahrenheit.

58. 54. The method of claim 53, wherein the whole body temperature is about 32 to about 33 degrees Celsius.

59. 54. The method of claim 53, wherein the blood is cooled for about 10 to about 15 minutes.

60. 54. The method of claim 53, wherein the mechanical circulatory assist system is inserted into the left side of the patient's heart.

61. 61. The method of claim 60, further comprising introducing an additional mechanical circulatory assist system to the right side of the patient's heart.

62. 62. The method of claim 61, further comprising the steps of unloading and cooling the right side of the heart while cooling and unloading the left side of the heart.

63. 54. The method of claim 53, wherein the mechanical circulatory assist system is powered by an internal motor.

64. 54. The method of claim 53, wherein the catheter further comprises a distal end, a proximal end, an inner surface, and an outer surface.

65. 65. The method of claim 64, wherein the lumen is configured to extend from the proximal end to the distal end of the catheter and back to the proximal end.

66. 65. The method of claim 64, wherein the lumen contacts an inner surface of the catheter.

67. 65. The method of claim 64, wherein a first path along which the lumen extends from a proximal end of the catheter to a distal end of the catheter forms a first spiral.

68. 68. The method of claim 67, wherein a second path along which the lumen extends from the distal end of the catheter to the proximal end of the catheter forms a second spiral.

69. 70. The method of claim 68, wherein the first and second helices are fluidly connected at a distal end of the catheter.

70. 70. The method of claim 68, wherein the first spiral and the second spiral are offset at an angle around a circumference of the catheter at a distal end of the catheter.

71. 71. The method of claim 70, wherein the angle of offset between the first helix and the second helix is ​​0 degrees.

72. 71. The method of claim 70, wherein the angle of offset between the first and second helices is 180 degrees, such that the first and second helices form a double helix.

73. 73. The method of claim 72, wherein the pitch of the double helix formed by the lumen is between about 1 millimeter and about 10 millimeters.

74. 73. The method of claim 72, wherein the double helix configured to contact the inner surface of the catheter covers 60% of the area of ​​the catheter.

75. 54. The method of claim 53, wherein the cooled solution comprises a crystalloid solution.

76. 76. The method of claim 75, wherein the crystalloid fluid is normal saline.

77. introducing a mechanical circulatory assist system including a cooling element within a catheter into the vascular system of a patient, the cooling element being a Peltier element including a first conductor and a second conductor, the first conductor and the second conductor having different electron densities and secured to a first wire configured to receive an electric current; placing the catheter within the vascular system such that an exterior surface of the catheter is in contact with blood flowing within the vascular system; activating a mechanical circulatory assist system; and passing an electrical current through the first wire to the junction of the first conductor and the second conductor while the mechanical circulatory assist system is operating to cool blood flowing through the patient's vascular system to a selected temperature to reduce or prevent the effects of the cardiac episode.

46. ​​A method for treating the effects of a cardiac episode in a patient comprising:

78. 78. The method of claim 77, wherein the selected temperature is selected to reduce or prevent the effects of a cardiac episode.

79. 80. The method of claim 78, wherein the cardiac episode is a myocardial infarction.

80. 80. The method of claim 78, wherein the effect of the cardiac episode is scarring.

81. 78. The method of claim 77, wherein the selected temperature is less than 37 degrees Fahrenheit.

82. 78. The method of claim 77, wherein the selected temperature is from about 32 to about 33 degrees Celsius.

83. 78. The method of claim 77, wherein the blood is cooled for about 10 to about 15 minutes.

84. 80. The method of claim 77, wherein the mechanical circulatory assist system is introduced into the left side of the patient's heart.

85. 85. The method of claim 84, further comprising introducing an additional mechanical circulatory assist system to the right side of the patient's heart.

86. 86. The method of claim 85, further comprising the steps of unloading and cooling the right side of the heart while cooling and unloading the left side of the heart.

87. 80. The method of claim 77, wherein the catheter further comprises a distal end, a proximal end, an inner surface, and an outer surface.

88. 88. The method of claim 87, wherein the Peltier element is configured to extend from a proximal end to a distal end of the catheter and back to the proximal end.

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