Cooled mechanical cycle support system and method of operation

Abstract

The invention relates to a cooled mechanical cycle support system and a method of operation. A mechanical circulation support system for the heart with cooling elements and a method for treating the effects of cardiac attacks using the system. The support system has a pump having a distal end and a proximal end, the pump including a rotor having at least one vane. 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 the pump housing. The outer surface of the catheter is configured to contact blood when disposed within a patient vasculature. The outer surface of the catheter includes a heat transfer surface configured for cooling blood in contact with the outer surface. The cooling element may be a helical or double helical shape extending along the surface of the catheter, or a Peltier element on the surface. The support system is operative to provide a selected temperature to cool circulating blood in contact with the outer surface of the catheter to a temperature selected to reduce or prevent the effects of cardiac attacks.

Description

[0001] This application is a divisional application of Chinese patent application 2020800391901 (PCT / US2020 / 028876), whose international filing date is April 18, 2020 and whose national phase entry date is November 26, 2021, and whose name is “Cooled mechanical circulatory support system and operation method”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 62 / 836,534, filed on April 19, 2019, and entitled “Cooled Impella,” the disclosure of which is hereby incorporated by reference. Technical Field Background Art

[0004] Mechanical circulatory support systems (e.g., intracardiac or intravascular blood pumps) can be introduced into the heart to deliver blood from the heart to the arteries. Such mechanical circulatory support devices are usually introduced to support the function of the heart after a patient's heart attack. One type of device is a group of devices called "Impella" heart pumps. Some blood pump assemblies can be introduced percutaneously through the vascular system during cardiac surgery. Specifically, the blood pump assembly can be inserted into the ascending aorta, through the aortic valve and into the left ventricle via catheterization through the femoral artery or axillary / subclavian artery. The inserted blood pump assembly can be configured to extract blood from the left ventricle of the heart through a cannula, and then discharge the blood into the aorta. The blood pump assembly can also be configured to extract blood from the inferior vena cava, and then discharge the blood into the pulmonary artery. Some mechanical circulatory support devices are powered by onboard motors, while others are powered by external motors and drive cables. Some blood pumps use external pumps outside the patient's body and long catheters extending through the vascular system and into the heart or other desired locations. Some blood pump systems are implanted by surgery, rather than by catheter implantation.

[0005] Heart attacks that require the use of a blood pump often result in a variety of adverse effects on the patient. Such heart attacks include myocardial infarction, cardiac arrest, high-risk percutaneous coronary intervention, cardiogenic shock, and left and right ventricular failure. In particular, patients who suffer a myocardial infarction, more commonly known as an MI, may have extensive scarring in their heart tissue. This scarring alters the normal conduction pathways of the heart and weakens the affected muscle. Depending on the size and location of the scar, the patient is at increased risk for arrhythmias, heart block, ventricular aneurysms, inflammation of the heart wall, and rupture of the heart wall, all of which can be fatal. Therefore, reducing or preventing this myocardial scarring is highly desirable. Summary of the invention

[0006] One known method for treating a myocardial infarction scar is induced systemic hypothermia, in which the blood flowing through the patient's heart is rapidly cooled to a desired systemic temperature. For example, the desired systemic temperature may be below (e.g., below 5 degrees Celsius) the patient's normal body temperature. Reducing the temperature in the blood sufficiently to the desired systemic temperature via systemic hypothermia cools the heart and thereby slows many physiological processes within the heart, such as metabolic reactions, tissue death, and myocardial scarring. However, currently used induced systemic hypothermia is known to cause arrhythmias in patients, which is particularly problematic for patients with myocardial scarring whose hearts are already increasingly weak. Therefore, in order to minimize the adverse effects of myocardial scarring, as well as to minimize the adverse effects of induced hypothermia, a system is desired that can simultaneously systemically cool the blood flow in order to prevent or reduce myocardial scarring while also preventing arrhythmias.

[0007] The systems, methods, and devices described herein provide a mechanical circulatory support system (e.g., a blood pump system) that is configured to reduce the workload on the heart while systemically cooling the patient's blood. The blood contacting surface of a blood pump or other circulatory support system can be configured as a heat transfer surface to perform 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, and the cooling can remove sufficient heat from the blood to induce a systemic hypothermia effect in the patient. The induced hypothermia effect slows down the biological processes that cause or aggravate the adverse effects of a heart attack. However, since inducing systemic hypothermia may cause arrhythmias, hypothermia treatment is induced simultaneously with the standard operation of a blood pump or other circulatory support system. In this way, when a blood pump or other circulatory support system circulates blood in the vascular system, the induced systemic hypothermia can reduce (or reverse) the adverse effects of a heart attack, thereby increasing nutrition to the heart (and other vascular systems) to prevent or avoid the adverse effects of induced systemic hypothermia. The systems, methods and devices described herein can be used to treat various vascular diseases, including but not limited to myocardial infarction, cardiac arrest, high-risk percutaneous coronary intervention, cardiogenic shock and left and right ventricular failure. In many adaptive modifications, the system described herein is a blood pump system for cooling the heart and providing mechanical circulatory support (e.g., by reducing the heart load) to the heart at the same time. In general, the blood pump system has a pump with a rotor having at least one blade that rotates in a pump housing surrounding (one or more) blades. In general, the pump is driven by a motor. Some pumps are powered by an onboard motor, while other pumps are powered by an external motor and a drive cable. Other pump systems have an external pump outside the patient's body and a long catheter (or cannula) extending to the heart (or other positions in the vascular system) in a blood vessel. The adaptive modification of the currently disclosed system may further include a catheter extending from the proximal end of the pump. Other adaptive modifications may include a pump system installed by surgery. In some embodiments, a flexible, non-traumatic protrusion extends from the distal end of the pump. For example, the flexible, non-traumatic protrusion may be of the pigtail type.

[0008] According to some aspects, the systems described herein include intravascular cooling surfaces that induce hypothermia. The cooling surface is configured to extend along the length of the catheter or other intravascular surface of the system and is positioned within the vascular system to contact the blood when the blood circulates in the patient's body. In some embodiments, the cooling element can be formed as a heat exchanger for the blood and can function by cooling the outer surface of the catheter (and then cooling the blood circulating through the patient's vascular system when the blood contacts the outer surface of the catheter). Similar cooling systems can be applied to other parts of the blood-contacting surface of the support system (e.g., pump housings) to replace the catheter or enhance the heat transfer effect of the catheter. In some adaptations, the heat transfer element is directly applied to the outer surface of the catheter (or other system components) so that the outer surface of the catheter (the surface that contacts the blood) is directly cooled; in such embodiments, the blood can directly contact the heat transfer element. In other adaptations, heat transfer occurs indirectly by positioning the heat transfer element within the thickness of the wall of the catheter or along the inner surface of the catheter, so that it first cools the interior or thickness of the wall of the catheter, and the thickness or inner surface cools the outer surface of the catheter through conduction of the wall thickness of the catheter.

[0009] At least one advantage of incorporating a cooling element into the pump system is the ability to regulate blood (and systemic vascular) temperature to prevent the adverse effects of a heart attack while preventing the adverse effects of the regulated temperature (e.g., induced systemic hypothermia).

[0010] According to a first embodiment of the present disclosure, a blood pump system for a heart includes a pump. The pump has a motor and a rotor and a heat transfer surface configured to be inserted into a patient and thermally regulated, for example, by a cooling element. The pump has a distal end and a proximal end. Typically, the rotor has at least one blade for transmitting blood through the pump. In some embodiments, the cooling element can be configured as an inner cavity to provide thermal fluid cooling, wherein the inner cavity is configured to deliver a freezing solution along the length of the catheter. In other embodiments, the cooling element can be configured as a Peltier device to provide thermoelectric cooling, wherein the Peltier device is configured to deliver current along the length of the catheter. The Peltier device may include a wire configured to deliver current to a junction of two semiconductor materials. The junction of the semiconductor may be arranged at any suitable point along the length of the catheter. Similarly, the semiconductor may be oriented in any suitable configuration so as to induce a desired heat flow along the length of the catheter. In some embodiments, the power supply for delivering current to the Peltier device is the same as the power supply for powering the pump. In other embodiments, the power supply for delivering current to the Peltier device is an external power supply different from the power supply for powering the pump.

[0011] The system also includes a pump housing that surrounds the at least one blade of the rotor. In intravascular applications, a catheter extends from the proximal end of the pump housing. The catheter has an inner surface and an outer surface and a proximal end and a distal end. When the catheter is disposed within the patient's vascular system, blood flows over the outer surface of the catheter. The pump system can alternatively be installed surgically without the need for a catheter, and the pump (or its cannula) can have a Peltier or other cooling element configuration.

[0012] In catheter applications, the cooling element extends along the length of the catheter, and the cooling element can be arranged in a variety of configurations. The cooling element can have a cross-section that is circular, elliptical, diamond-shaped, rectangular, linear, or other shapes. The geometry of the cross-section can be adjusted to adjust the percentage of the inner surface of the catheter that is in contact with the cooling element. For example, in an embodiment with a circular cross-section, if the area of ​​the cross-section is increased, a larger portion of the inner surface of the catheter is in contact with the cooling element, and the heat transfer rate and the total amount of heat transferred can be increased.

[0013] According to some aspects, the cooling element can contact with the catheter or other blood contact system components to provide thermal control of the components, and therefore provide the desired thermal control and / or regulation (e.g., cooling) of the blood. If necessary, the cooling element can also be configured to increase the temperature, for example, to increase the temperature of the blood. In order to cool the vascular system, the cooling element cools the blood contact surface of the catheter (or other system components) to a temperature lower than the whole body temperature of the blood. For example, in many applications, the temperature to which the blood contact surface of the catheter is cooled can be about 32 degrees Celsius. In some embodiments, the cooling element contacts the outer surface of the catheter or other system components. In other embodiments, the cooling element contacts a part of the inner surface of the catheter (via the side lumen or embedded in the wall of the catheter or other system components), and in those embodiments, 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 can extend along the catheter length, and then can be further extended to another system component. For example, another system component to which the cooling element can extend is a pump housing. The outer surface of the catheter can therefore be indirectly cooled to a desired temperature (e.g., below systemic blood temperature), and the outer surface can then cool blood in contact with the outer surface of the catheter or other system components. The blood in the heart is cooled until the desired systemic temperature is reached. Cooling can be done quickly. For example, the blood can be systemically cooled for a period of time between about 5 minutes and about 20 minutes. In other embodiments, the period is between about 7.5 minutes and about 17.5 minutes. In further embodiments, the period is between about 10 minutes and about 15 minutes. In some embodiments, the period is about 12.5 minutes. In certain embodiments, the blood is cooled in less than 5 minutes. In other embodiments, the blood is cooled in less than 3 minutes.

[0014] In certain embodiments, the blood is cooled to a systemic temperature of less than 37 degrees Celsius. In some embodiments, the blood is cooled to a systemic temperature between about 30 degrees Celsius and about 35 degrees Celsius. In other embodiments, the blood is cooled to a systemic temperature ranging between about 31 degrees Celsius and about 34 degrees Celsius. In further embodiments, the blood is cooled to a systemic temperature between about 32 degrees Celsius and about 33 degrees Celsius. Cooling the blood circulating in the patient's body provides a hypothermic effect that slows down biological processes that cause or exacerbate the negative effects of a heart attack. Specifically, cooling the blood after a patient suffers a myocardial infarction can slow down the processes that cause myocardial scarring in the patient's heart, while at the same time preventing the negative effects of pumping blood to the heart that are known to be induced by induced systemic hypothermia.

[0015] In some embodiments, the cooling element can be configured as an inner cavity, and the inner cavity can be configured to deliver a freezing solution along the length of the catheter. Injecting the freezing solution into the inner cavity can induce a cryogenic effect in the patient. In order to deliver this cryogenic effect, at least a portion of the inner cavity can be a side inner cavity in contact with a portion of the inner surface of the catheter. Alternatively, at least a portion of the inner cavity can be embedded in the wall of the catheter. The specific portion of the inner cavity that is selected to contact the inner surface of the catheter or to be embedded in the wall of the catheter can be selected so as to achieve a desired heat transfer rate along a portion of the catheter. Specific heat transfer rates at different regions along the length of the catheter may be beneficial for treating the negative effects of certain heart attacks. For example, in some embodiments, half of the inner cavity can be in contact with a portion of the inner surface of the catheter. In other embodiments, three quarters of the inner cavity can be in contact with a portion of the inner surface of the catheter. Similarly, half of the inner cavity can be embedded in the wall of the catheter. In other embodiments, three quarters of the inner cavity can be embedded in the wall of the catheter. When the flow of the freezing solution cools the inner surface of the catheter, the heat transfer surface of the catheter is cooled. The heat transfer surface of the catheter then cools the blood, thereby inducing a hypothermic effect in the patient. The inner cavity has a first proximal opening and a second proximal opening. The first proximal opening can be configured as an inlet for a freezing solution, and the second proximal opening can be configured as an outlet for a freezing solution. The inner cavity can be configured to include two parts, a first flow portion and a second flow portion, which extend 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 the flow of the freezing solution from the proximal end of the catheter to the distal end of the catheter in a distal direction. The second flow portion extends from the distal end of the catheter to the second proximal opening and accommodates the flow of the freezing solution from the distal end of the catheter to the proximal end of the catheter in a proximal direction. The first flow portion and the second flow portion can extend along equal lengths of the catheter. The first flow portion can be from the first proximal opening at the proximal end of the catheter to the distal end of the catheter, and defines a first lumen path length, along which the inner cavity extends.

[0016] The first lumen path length can be equal to the catheter length along which the lumen extends. The second flow portion can be from the distal end of the catheter to the second proximal opening at the proximal end of the catheter, and defines a second lumen path length, along which the lumen extends. The second lumen path length can be equal to the catheter length along which the lumen extends. In some embodiments, the first lumen path length can be greater than the second lumen path length. In other embodiments, the first lumen path length can be equal to the second lumen path. The catheter length along which the lumen extends can be three-quarters of the catheter length. In other embodiments, the catheter length along which the lumen extends can be half of the catheter length. In certain embodiments, the lumen extends along the entire length of the catheter. The catheter length along which the lumen extends allows the freezing solution to be delivered along the same length of the catheter. In such an embodiment, after the freezing solution is injected into the first proximal opening, and after the fluid has extended along the first flow portion, it extends along the second flow portion and leaves the system from the second proximal opening. At least one advantage of a blood pump configured with an inner lumen to receive a cryogenic solution is that the pump can simultaneously induce systemic hypothermia to treat the adverse effects of a heart attack while also offloading the heart to treat the adverse effects of systemic hypothermia (including arrhythmias).

[0017] The lumen can be configured in a catheter in a variety of different ways. In some embodiments, the lumen can be configured to contact the inner surface of the catheter. For example, the lumen can be configured to contact the inner surface of the catheter when it extends along the first flow portion, the first flow portion defining the first lumen path length. The first flow portion can extend along any suitable path (including but not limited to straight or spiral). The lumen can then be configured to extend through the center of the catheter along the second flow portion, the second flow portion defining the second lumen path length. In other embodiments, a portion of the lumen can be embedded in the wall of the catheter. For example, the first flow portion of the lumen can be embedded in the wall of the catheter, while the second flow portion extends through the center of the catheter. In other embodiments, the first flow portion of the lumen can extend through the center of the catheter, while the second flow portion is embedded in the wall of the catheter. In some embodiments, both the first flow portion and the second flow portion are embedded in the wall of the catheter. The second flow portion can also be configured in a variety of geometric shapes, including but not limited to straight or spiral. Keeping the second flow portion out of contact with the inner surface of the catheter keeps the solution that has absorbed heat from the blood away from the inner surface of the catheter, thereby allowing a faster temperature reduction in the blood. The specific orientation of the lumen within the catheter can be adjusted to direct heat into and out of different areas along the length of the catheter.

[0018] In addition, the flow of the freezing solution can be reversibly configured in the inner cavity. As described above, the inner cavity can be configured to extend from the first proximal opening at the proximal end of the catheter to the distal end of the catheter along the catheter length. The inner cavity can extend along the catheter length in various ways. In some embodiments, a part of the inner cavity can contact the inner surface of the catheter. In other embodiments, a part of the inner cavity can be embedded in the wall of the catheter. Usually, the inner cavity is configured to receive a freezing fluid. The freezing fluid cools the surface of the catheter, which cools the heat transfer surface of the catheter by thermal conduction. The heat transfer surface induces a systemic effect in the patient's blood. In such an embodiment, the freezing solution can be injected into the first proximal opening, thereby allowing the first proximal opening to be used as the inlet of the freezing solution, and allowing the freezing solution to flow from the proximal end of the catheter to the distal end of the catheter along the first flow portion. In such an embodiment, the fluid travels to the second proximal opening from the distal end of the catheter to the proximal end of the catheter along the second length of the catheter, thereby allowing the second proximal opening to be used as the outlet of the freezing solution. Since the flow of the frozen solution can be reversibly configured in the inner cavity, in other embodiments, the frozen solution is first injected into the second proximal opening, thereby allowing the second proximal opening to be used as an inlet for the frozen solution and allowing the frozen solution to flow from the proximal end of the catheter to the distal end of the catheter along the second flow portion. In such an embodiment, the fluid returns to the first proximal opening from the distal end of the catheter to the proximal end of the catheter along the first flow portion, thereby allowing the first proximal opening to be used as an outlet for the frozen solution. This reversibility of the flow of the frozen solution is applicable to all embodiments comprising an inner cavity.

[0019] In some embodiments, the path formed by the lumen when the lumen extends from one end of the catheter to the other end is spiral. For example, the lumen can form a single spiral when it extends along the first flow portion. Single spiral is defined as a single strand (e.g., a single lumen, wire or semiconductor) shaped as a spiral in this article. The lumen can then be configured to return through the center of the catheter along the second flow portion. In other embodiments, this situation can be reversed. Specifically, the lumen can extend through the center of the catheter along the first flow portion. The lumen can then be configured to return along the second flow portion spirally. As previously mentioned, the specific geometry of the lumen in the catheter can be used to import and export heat into a specific area of ​​the catheter. Therefore, the direction of heat can be controlled so that a specific heat distribution is generated along the catheter. For example, some patient pathologies or anatomical structures may benefit from a specific heat distribution. In the configuration where the single spiral contacts the inner surface of the catheter, an advantage is that the blood can be cooled quickly because the flow direction of the freezing solution through the lumen can be selected so that the fluid that has absorbed the heat from the blood does not contact the inner surface of the catheter. At least one advantage of a mechanical circulatory support device (e.g., a blood pump) having an inner lumen extending helically along the length of the catheter is that such a pump can effectively cool the blood to induce systemic hypothermia to treat the negative effects of a heart attack, while also supporting the heart to offset the negative effects of the induced systemic hypothermia.

[0020] In other embodiments, the lumen extends in two directions along a spiral. The lumen extends along the first flow portion along the first spiral, and the lumen extends along the second flow portion along the second spiral. The first spiral and the second spiral of the lumen are fluidly connected at the distal end of the catheter. In such an embodiment, the first spiral and the second spiral can be offset by an angle along the circumference of the catheter to form a double spiral. The double spiral as defined herein includes two spirals with the same pitch and radius oriented 180 degrees to each other along the circumference of the catheter. In an embodiment in which the first spiral and the second spiral do not offset an angle along the circumference of the catheter, the first spiral and the second spiral form a double-width single spiral. The double-width single spiral as defined herein includes two single spirals with the same pitch and the same radius, which contact each other at each point along their length. In other embodiments, the first spiral and the second spiral can be offset by an intermediate angle along the circumference of the catheter. The intermediate angle can be between 0 and 180 degrees. For example, the first spiral and the second spiral can be offset by about 45 degrees along the circumference of the catheter. In other embodiments, the first helix and the second helix can be offset by about 90 degrees along the circumference of the catheter. In some embodiments, the first helix and the second helix can be offset by about 135 degrees along the circumference of the catheter. At least a portion of the helical element (whether forming a double helix, a double-width single helix, or any other configuration) contacts the inner surface of the catheter.

[0021] In some embodiments, the pitch of the double helix formed by the cooling element is between about 1 mm and about 10 mm. In further embodiments, the pitch of the double helix formed by the cooling element is between about 3 mm and about 8 mm. In other embodiments, the pitch of the double helix formed by the cooling element is between about 5 mm and about 6 mm. In certain embodiments, the pitch of the double helix formed by the cooling element is about 5.5 mm. The variability of the pitch of the helix formed by the cooling element is used to create a specific heat profile and heat transfer profile along the catheter.

[0022] In some embodiments, the double helix formed by the cooling element covers between about 30% and about 90% of the inner surface of the catheter. In other embodiments, the double helix formed by the cooling element covers between about 40% and about 80% of the inner surface of the catheter. In certain embodiments, the double helix formed by the cooling element covers between about 50% and about 70% of the inner surface of the catheter. In some embodiments, the double helix formed by the cooling element covers about 60% of the inner surface of the catheter. Embodiments of the blood pump having a larger inner surface area covered by the cooling element allow the blood to be cooled more quickly while still providing support to the heart to combat the negative effects of induced systemic hypothermia.

[0023] In an embodiment with a lumen configured as a double helix, a first single helix extending along a first flow portion and a second single helix extending along a second flow portion are fluidly connected at the distal end of the catheter. Specifically, the lumen first extends along the first flow portion while extending along the first helix. The lumen can then extend along the second flow portion while extending along the second helix. After the lumen extends along the first flow portion, the lumen extends along the length of the catheter circumference at a fixed longitudinal point. When the lumen extends along the length of the catheter circumference, it can contact the inner surface of the catheter. In a double helix configuration, the lumen extends along half of the catheter circumference at a fixed longitudinal point, so that the first helix and the second helix are offset by 180 degrees along the catheter circumference. At least one advantage of an embodiment with a lumen configured in a double helix shape is that by changing the pitch of the double helix, different cooling rates and different heat distribution diagrams along the length of the catheter can be achieved.

[0024] In other embodiments, the lumen forms a double-width single helix, as defined above, and the double-width single helix includes two single helices with the same pitch and the same radius, and the two single helices 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 along which the lumen extends extends along the first flow portion, and the second single helix along which the lumen extends extends along the second flow portion, and the first single helix and the second single helix together form a double-width single helix. Specifically, the lumen extends along the first flow portion while extending along the first helix. The lumen can then extend along the second flow portion while extending along the second helix. After the lumen extends along the first flow portion, the lumen extends along the length of the circumference of the conduit at a fixed longitudinal point. In a double-width single helix configuration, the lumen extends along the entire circumference of the conduit at a fixed longitudinal point, so that the first helix and the second helix are offset at an angle of 0 degrees along the circumference of the conduit. The pitch of the double-width single helix can be adjusted to produce a certain heat distribution diagram along the conduit.

[0025] In some embodiments, a freezing solution is injected into the inner chamber to cool the blood. The freezing solution may include a crystalloid. The crystalloid may be a saline solution (a solution containing 9 grams of sodium chloride per liter of solution), lactated Ringer's solution, 1 / 3NS2 / 3D5 or glucose. Typically, a solution with the highest heat capacity is selected because such a solution can cool the blood most rapidly without experiencing a temperature rise, thereby keeping the solution in contact with the inner surface of the catheter along two lengths of the catheter. A blood pump with an inner chamber configured to receive the freezing solution is therefore able to cool blood quickly, so as to treat the negative effects of a heart attack, while also alleviating the heart load to provide support to avoid the negative effects of induced systemic hypothermia.

[0026] As an alternative to the cooling element of the inner cavity configured to deliver the freezing solution along the length of the catheter, in some embodiments, the cooling element is a Peltier device. The Peltier device can be embedded in the wall of the catheter, or attached along the outer surface or inner surface of the catheter. In other embodiments, the Peltier device is embedded in the pump housing or other blood contact parts of the blood pump system. The Peltier device can be fused to another blood contact part of the catheter, pump housing or blood pump system. In other embodiments, the Peltier device can be attached to another blood contact part of the catheter, pump housing or blood pump system with an adhesive. Generally, the Peltier device can be configured to extract heat from any combination of another part of the catheter, pump housing or blood pump system. The Peltier device drives the heat transfer between two semiconductor materials with different characteristics. For example, the electron density of the two semiconductor materials can be different (for example, one material can be an n-type semiconductor and the other material can be a p-type semiconductor). The Peltier device can be configured into a variety of geometric shapes. In particular, the Peltier device includes two semiconductor materials forming a junction, and the junction can be arranged in various different configurations to guide heat flow in the desired direction. Typically, the junction can be placed at any suitable point along the length of the catheter to achieve the desired heat distribution and heat exchange rate along the length of the catheter. For example, the semiconductor material can be oriented so that the heat flow is guided in the radial direction, or the semiconductor material can be oriented so that the heat flow is guided longitudinally along the catheter length. The semiconductor material can be further arranged to allow the current to be delivered to any configuration of the junction formed by the semiconductor material. In some embodiments, the power supply for delivering the current to the Peltier device is the same as the power supply for powering the pump. In other embodiments, the power supply for delivering the current to the Peltier device is different from the power supply for powering the pump. The current is delivered to the junction of the semiconductor material and causes cooling by the Peltier effect, wherein cooling occurs when a voltage is established at the junction of two semiconductor materials (e.g., n-type semiconductors and p-type semiconductors) with different electron densities, and the junction includes a first semiconductor material and a second semiconductor material. The application of the Peltier effect causes the temperature of the semiconductor material in contact with the inner surface of the catheter to drop and acts as a heat sink to cool the blood in contact with the outer surface of the catheter to the whole body temperature. In some embodiments, the junction is arranged in the surface of the catheter towards the distal end of the catheter. In other embodiments, the junction may be disposed within the wall of the catheter toward the proximal end of the conductor.

[0027] The first semiconductor material can be configured to extend twice along the length of the catheter. The first length of the catheter along which the semiconductor conductor material extends is generally equal to the second length of the catheter along which the semiconductor material extends. The first length of the catheter along which the semiconductor material extends can be from the proximal end of the catheter to the distal end of the catheter. The second length of the catheter along which the semiconductor material extends can be from the distal end of the catheter to the proximal end of the catheter. The first length of the catheter along which the semiconductor material extends can 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 semiconductor material extends can 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 an embodiment using a Peltier device is the ability to select and combine various semiconductor materials in order to produce a specific heat exchange rate and a specific heat distribution along the catheter. Therefore, incorporating a Peltier device into a blood pump provides cardiac support to overcome the negative effects of induced systemic hypothermia while also allowing systemic hypothermia to be induced to treat the negative effects of a heart attack.

[0028] In embodiments having a Peltier device as a cooling element, the current delivered to the junction of the semiconductor material of the Peltier device can be in a range between about 0.01 amps and about 3 amps. In some embodiments, a current between about 0.1 amps and about 2 amps is delivered to the junction of the semiconductor material of the Peltier device. In further embodiments, a current between about 0.5 amps and 1.5 amps is delivered to the junction of the semiconductor material of the Peltier device. In certain embodiments, a current of about 1 amp is delivered to the junction of the semiconductor material of the Peltier device. The specific current flowing through the wire of the Peltier device can be adjusted to produce a certain potential difference at the junction of the semiconductor material, thereby allowing a certain heat distribution and blood cooling rate to be achieved along the catheter.

[0029] According to some aspects of the present disclosure, a method for treating the effects of a heart attack in a patient includes first introducing a mechanical circulatory support device into the patient's vasculature. The mechanical circulatory support system can be a blood pump. The blood pump includes a cooling element, such as a fluid lumen or a Peltier device, disposed within a catheter. After the blood pump is introduced into the patient's vasculature, a physician performing the method positions the catheter within the vasculature so that an outer surface of the catheter contacts blood flowing through the vasculature. The physician then actuates the blood pump to circulate the blood through the patient's body. While actuating the blood pump, the physician activates the cooling element. As previously described, the cooling element acts as a heat exchanger by cooling the inner surface of the catheter. The inner surface of the catheter then cools the outer surface of the catheter, which then cools the patient's blood. This cooling is performed over a selected period of time to ensure that the outer surface of the catheter reaches a selected temperature. The temperature of the outer surface of the catheter is selected so that blood in contact with the outer surface of the catheter is cooled to systemic temperature. The temperature to which the outer surface is cooled can be less than or equal to systemic temperature. Specifically, the blood is cooled to a selected systemic temperature in order to treat the effects of a heart attack. In some embodiments, the heart attack can be a myocardial infarction, and in some embodiments, the effect of a myocardial infarction is myocardial scarring.

[0030] In some embodiments, the blood pump is inserted into the left side of the patient's heart so that the system helps unload the patient's left ventricle. In other embodiments of the method, the blood pump is inserted into the right side of the patient's heart so that the system helps unload the patient's right ventricle.

[0031] In certain embodiments, a first blood pump is introduced into one side of the patient's heart and a second blood pump is introduced into the other side of the patient's heart. In some embodiments, a first blood pump is introduced into the right side of the patient's heart and a second blood pump is introduced into the left side of the patient's heart. In other embodiments, a first blood pump is introduced into the left side of the patient's heart and a second blood pump is introduced into 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 can allow a physician to cool the heart even faster than cooling one side, while supporting the heart in parallel to prevent the adverse effects of induced systemic hypothermia.

[0032] In another embodiment, a method for treating the effects of a heart attack in a patient includes first introducing a mechanical circulatory support device into the patient's vasculature, the mechanical circulatory support device including an inner cavity disposed within a catheter. The mechanical circulatory support device of the method can be a blood pump. After the blood pump is introduced into the vasculature, a physician performing the method of this embodiment positions the catheter within the patient's vasculature so that the outer surface of the catheter contacts the blood flowing within the vasculature. Once the blood pump is properly positioned, the physician actuates the blood pump, and while the system is actuated, the physician injects a freezing solution into the inner cavity. Injecting the freezing solution into the inner cavity cools the outer surface of the catheter to a certain temperature for a period of time, and the temperature of the outer surface of the catheter is selected so that the circulating blood in contact with the outer surface of the catheter is cooled to the whole body temperature. The temperature to which the outer surface of the catheter is cooled can be less than or equal to the whole body temperature. The whole body temperature is selected to reduce or prevent the effects of a heart attack. In some embodiments, the heart attack is a myocardial infarction, and the effect of the myocardial infarction is myocardial scarring. Such an embodiment provides the advantage that the cryogenic solution inserted into the inner cavity is able to induce systemic hypothermia in the patient's blood in order to treat or prevent the negative effects of a heart attack, while the pump circulates the blood through the patient's body (e.g., by reducing the workload on the heart) in order to prevent negative side effects that may be caused by the induced systemic hypothermia.

[0033] In another embodiment, a method for treating the effects of a heart attack in a patient includes first introducing a mechanical circulatory support device into the patient's vascular system. The mechanical circulatory support device can be a blood pump. The blood pump of this embodiment includes a Peltier device disposed within a catheter, the Peltier device including a junction of two semiconductor materials having different electron densities. After the blood pump is introduced into the vascular system, a physician performing the method of this embodiment positions the catheter within the patient's vascular system so that the outer surface of the catheter contacts the blood flowing within the vascular system. Once the blood pump is properly positioned, the physician actuates the blood pump, and while actuating the blood pump, the physician causes an electric current to flow through a first wire. The cooled semiconductor material cools the outer surface of the catheter through the Peltier effect (wherein the current flowing between the junction of the two semiconductor materials allows heat to be removed from one of the semiconductor materials). This cooling continues for a period of time until the outer surface of the catheter reaches a certain temperature, and the temperature of the outer surface of the catheter is selected so that the circulating blood in contact with the outer surface of the catheter is cooled to the systemic temperature. The systemic temperature is selected to reduce or prevent the effects of a heart attack. In some embodiments, the heart attack is a myocardial infarction, and the effect of the myocardial infarction is myocardial scarring. Thus, a pump configured with a Peltier device can provide support to the heart to prevent the negative effects of induced systemic hypothermia while still inducing systemic hypothermia to treat or prevent the negative effects of a heart attack.

[0034] In certain embodiments of the method, a first blood pump comprising a Peltier device is introduced into one side of the patient's heart and a second blood pump comprising a Peltier device is introduced into the other side of the patient's heart. In some embodiments, the first blood pump comprising a Peltier device is introduced into the right side of the patient's heart and the second blood pump comprising a Peltier device is introduced into the left side of the patient's heart. In other embodiments, the first blood pump comprising a Peltier device is introduced into the left side of the patient's heart and the second blood pump comprising a Peltier device is introduced into the right side of the patient's heart. Such embodiments include cooling and unloading both sides of the patient's heart simultaneously. Unloading both sides of the heart and cooling both sides of the heart simultaneously allows the physician to cool the blood in the heart more quickly, thereby preventing the effects of a heart attack, while preventing the negative effects of induced systemic hypothermia by unloading the heart. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A pictorial example of a mechanical circulatory support system with a cooling element for a heart is shown, the components of the mechanical circulatory support system being Figure 7 As shown in more detail in;

[0036] Figure 2 A diagrammatic perspective view of a portion of a mechanical circulatory support system for a heart having a cooling element is shown;

[0037] Figures 3A-3C A pictorial example of a cross section of a double-width single helical shape is shown;

[0038] Figure 4 A pictorial method for treating myocardial infarction while simultaneously unloading the heart is shown;

[0039] Figure 5 A pictorial method of treating myocardial infarction while simultaneously unloading the heart using a mechanical circulatory support system configured with an inner lumen is shown; and

[0040] Figure 6 A pictorial method of treating myocardial infarction while simultaneously unloading the heart using a mechanical circulatory support system configured with a Peltier device is shown. DETAILED DESCRIPTION

[0041] To provide an overall understanding of the systems, methods, and devices disclosed herein, certain illustrative embodiments will be described. Although the embodiments and features described herein are specifically described for use in conjunction with a pump for a heart, it should be understood that the teachings may be applicable and applied to other pumps and other types of medical devices.

[0042] The systems, methods and devices described herein provide a mechanical circulatory support system for a heart that is configured to simultaneously unload the heart while also inducing hypothermia in a patient to cool the patient's blood in order to reduce or prevent the harmful effects of a heart attack. Specifically, the systems, methods and devices described herein provide a pump having a systemic cooling element along the length of a catheter of the pump that is configured to induce hypothermia within the patient's heart in order to reduce or prevent scarring caused by a myocardial infarction.

[0043] Figure 1 A pictorial example of a mechanical circulatory support system or blood pump 100 for a heart having a cooling element that enables the pump to simultaneously relieve the heart while inducing hypothermia in a patient is shown. Figure 1 The cooling element is shown extending along a single helix as the cooling element extends in one direction along the length of the catheter. As previously mentioned, a single helix as defined herein refers to a single strand that is helical in shape. The heart pump 100 also 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, the motor 104, and the pump housing 106 is shown in FIG. Figure 7 1. The cooling element 116 has a diameter 128, and the conduit 118 has a radius 130. The helical shape formed by the cooling element 116 has a pitch 132. The conduit 118 extends from the proximal end 110 of the pump housing 106 in a proximal direction. The cooling element 116 is disposed within the conduit 118. Figure 1As shown, the cooling element 116 extends along the length L1 of the catheter 118 before it doubles back on itself. However, the cooling element 116 can be configured to extend along the illustrated length L2 of the catheter 118 or along any other length of the catheter 118 so that systemic cooling of the patient's blood can be achieved when the blood pump 100 is deployed within the heart or other parts of the vasculature. The cooling element 116 is therefore generally configured to extend twice along 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 simultaneously induce hypothermia within the patient's heart in order to prevent or reduce the harmful effects of a heart attack, while also relieving the heart from the harmful effects that would normally be encountered when hypothermia is induced into the patient's heart. The heart attack requiring the use of such a pump may be a myocardial infarction or MI, and the effect of such an attack may be myocardial scarring. The reduced temperature of a patient's blood subjected to induced hypothermia generally slows one or more of the biological processes that lead to myocardial scarring, thereby helping to prevent the patient from sustaining long-term damage to the heart following a heart attack.

[0044] The cooling element 116 can be arranged in a variety of different geometric shapes within the catheter. As previously mentioned, the cooling element 116 can extend along any suitable length of the catheter 118 before it folds back on itself. Figure 1 Two such illustrated lengths L1 and L2 are shown in FIG. The cooling element 116 may extend along any other suitable length of the conduit 118. In addition, the cooling element 116 may be oriented in a different geometry along each of the two lengths of the conduit 118 along which the cooling element 116 extends. For example, in FIG. Figure 1 In 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. Once the cooling element 116 extends along the length L1, it can turn back and extend in a spiral as it extends from the distal end 124 of the catheter 118 to the proximal end 126 of the catheter 118. Figure 1In the embodiment, the cooling element 116 can be constrained to the inner surface 120 of the catheter 118 along its spiral shape extending from the distal end 124 of the catheter 118 to the proximal end 126 of the catheter 118. In the embodiment where the cooling element 116 is a lumen, the freezing solution is injected into the cooling element 116. As previously described, for a given geometry of the cooling element 116 including a lumen, the flow direction of the freezing solution within the lumen is reversible. In such an embodiment, the freezing fluid can be injected into either length of the element 116, so that the freezing solution can first extend downward along the straight portion of the element 116 and then extend back along the spiral portion of the element 116 toward the proximal end 126 of the catheter 118, or the freezing fluid can first extend downward along the spiral portion of the cooling element 116 and then extend back along the straight portion of the element 116 toward the proximal end 126 of the catheter 118.

[0045] The helical pitch 132 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 can vary between embodiments. For example, the helical pitch 132 along which the cooling element 116 extends can be between about 1 millimeter and about 21 millimeters. In some embodiments, the helical pitch 132 along which the cooling element 116 extends can be between about 3 millimeters and about 19 millimeters. In other embodiments, the helical pitch 132 along which the cooling element 116 extends can be between about 5 and about 17 millimeters. In certain embodiments, the helical pitch 132 along which the cooling element 116 extends can be between about 7 millimeters and about 15 millimeters. In further embodiments, the helical pitch 132 along which the cooling element 116 extends can be between about 9 millimeters and about 13 millimeters. In other embodiments, the helical pitch 132 along which the cooling element 116 extends can be about 11 millimeters. At least one advantage of the helical variable pitch 132 formed by the cooling element 116 is that the specific geometry of the cooling element can be selected to produce a desired internal surface area covered by the cooling element 116 .

[0046] Similarly, diameter 128 can be selected to achieve the desired covered inner surface area. For example, diameter 128 can be between about 0.5 mm and about 7.5 mm. In other embodiments, diameter 128 can be between about 1 mm and about 7 mm. In further embodiments, diameter 128 can be between about 1.5 mm and about 6.5 mm. In certain embodiments, diameter 128 can be between about 2 mm and about 6 mm. In other embodiments, diameter 128 can be between about 2.5 mm and about 5.5 mm. In other embodiments, diameter 128 can be between about 3 mm and about 5 mm. In further embodiments, diameter 128 can be about 4 mm.

[0047] The distance between the straight portion of the cooling element 116 and the inner surface 120 of the conduit 118 can also be adjusted to produce a specific temperature profile along the length of the device. For example, the straight portion of the cooling element can extend directly down the center of the conduit 118. In other embodiments, the straight portion of the cooling element can extend down the length of the conduit 118 midway between the center of the conduit 118 and the inner surface 120 of the conduit 118. A smaller distance between the straight portion of the cooling element 116 and the inner surface 120 of the conduit 118 corresponds to a lower temperature of the outer surface 122 of the conduit 118. Conversely, a larger distance between the straight portion of the cooling element 116 and the inner surface 120 of the conduit 118 corresponds to a higher temperature of the outer surface 122 of the conduit 118.

[0048] In some embodiments, the cooling element 116 extends along a first helix as it extends from the proximal end 126 of the catheter 118 to the distal end 124 of the catheter 118. Once the first helix extends along the desired length along the catheter 118, it then doubles back on itself and forms a second helix as it extends from the distal end 124 of the catheter 118 to the proximal end 126 of the catheter 118. The two helices may be circumferentially offset from each other by an angle between 0 and 180 degrees.

[0049] Embodiments in which the angle between the two helices is 180 degrees define a cooling element configured as a double helix. In such embodiments, once the first helix extends along the catheter from the proximal end 126 of the catheter 118 to the distal end 124 of the catheter 118 along a first length, it extends along a semicircle of the catheter 118 at a given longitudinal point along the length of the catheter 118. After extending along the semicircle, the second helix along which the cooling element 116 extends can extend along the 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 can have a variable pitch. For example, the pitch of the double helix along which the cooling element 116 extends can be between about 1 mm and about 21 mm. In some embodiments, the pitch of the double helix along which the cooling element 116 extends can be between about 3 mm and about 19 mm. In other embodiments, the pitch of the double helix along which the cooling element 116 extends can be between about 5 and about 17 mm. In certain embodiments, the pitch of the double helix along which the cooling element 116 extends can be between about 7 mm and about 15 mm. In further embodiments, the pitch of the double helix along which the cooling element 116 extends can be between about 9 mm and about 13 mm. In other embodiments, the pitch of the double helix along which the cooling element extends can be about 11 mm. As previously described, embodiments in which the angle between the two helices is 0 degrees define a cooling element configured as a double-wide single helix. A double-wide single helix as defined above includes two single helices having the same pitch and the same radius that touch at every point along their length.

[0050] In some embodiments, the conduit radius 130 may correspond to the radius of the spiral formed by the cooling element 116. In such embodiments, the cooling element 116 is constrained to the inner surface 120 of the conduit 118. In other embodiments, the conduit radius 130 may be greater than one or both of the radii of the spiral formed by the cooling element 116. For example, a first spiral formed by the cooling element 116 may be constrained to the inner surface 120 of the conduit 118, while the second spiral may have a radius between about 1 / 6 and about 5 / 6 of the conduit radius 130. In other embodiments, the radius of the second spiral is between about 1 / 3 and about 2 / 3 of the conduit radius 130. In further embodiments, the second spiral formed by the element 116 may have a radius of about 1 / 2 of the conduit radius 130. In embodiments where the offset angle between the first spiral and the second spiral is not 180 degrees, the two spirals may form a single double-width spiral. This configuration is further discussed below in conjunction with FIG. 3.

[0051] Figure 2A diagrammatic perspective view of a portion of a mechanical circulatory support system or blood pump 200 for a heart having a cooling element 210 configured in a double helix is ​​shown. The illustrated blood pump system 200 includes a catheter 202 having an inner surface 204, an outer surface 206, and a radius 208, and the cooling element 210. Figure 2 In the embodiment, the cooling element 210 is arranged in a double helix, comprising two single helices with a pitch 212. Figure 2 The double helical shape of the cooling element 210 shown has a radius equal to the conduit radius 208. Thus, Figure 2 The cooling element 210 is shown constrained to the inner surface 204 of the conduit 202. In some embodiments, the conduit radius 208 can be greater than one or both of the radii of the spirals formed by the cooling element 210. For example, a first spiral formed by the cooling element 210 can have a radius equal to the conduit radius 208 so that it is constrained to the inner surface 204 of the conduit 202, while a second spiral can have a radius between about 1 / 6 and 5 / 6 of the conduit radius 208. In other embodiments, the radius of the second spiral is between about 1 / 3 and 2 / 3 of the conduit radius 208. In further embodiments, the second spiral formed by the element 210 can have a radius of about 1 / 2 of the conduit radius 208. In other embodiments, both the first spiral and the second spiral have a radius less than the conduit radius 208. For example, in some embodiments, the first spiral and the second spiral have a radius between about 1 / 6 and about 5 / 6 of the conduit radius 208. In other embodiments, the first helix and the second helix have a radius between about 1 / 3 and about 2 / 3 of the conduit radius 208. In some embodiments, the first helix and the second helix have a radius between about 1 / 3 and about 2 / 3 of the conduit radius 208.

[0052] As previously mentioned Figure 1 As discussed, the first helix and the second helix formed by the element 210 can be circumferentially offset from each other by an angle ranging between 0 and 180 degrees. Thus, the first helix and the second helix formed by the element 210 can be configured as a double helix or a double-width single helix. Figure 2 In the illustrated embodiment of the present invention, the first helix and the second helix are offset by an angle of 180 degrees so that they form a double helix as defined above. As discussed below with respect to FIG. 3 , the two helices may be offset by an angle of zero degrees so that they form a double-width single helix along the length of the catheter 202 .

[0053] In some embodiments, the cooling element 210 forms only one spiral along the length of the conduit 202. For example, the cooling element 210 may extend downward in one direction along the center of the conduit 202 and may extend in another direction in a spiral along the inner surface 204 of the conduit 202. The specific geometry of the cooling element 210 within the conduit 202 may be adjusted to produce a specific temperature profile along the length of the conduit 202.

[0054] Figure 3A , Figure 3B and Figure 3C Three pictorial examples of cross-sections of catheters containing cooling elements for use in mechanical circulatory support systems or blood pumps for the heart are shown. Figure 3A , Figure 3B and Figure 3C A cross section of a catheter containing a lumen configured as a cooling element is depicted, however, as previously mentioned, the cooling element may also be a Peltier device. Figure 3A A schematic cross-section of a cooling element for use in a blood pump system 300 for a heart having a first lumen 302, a second lumen 304, a lumen channel 306, and a conduit 308 is shown. Figure 3A In the embodiment, 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. Figure 3A In the embodiment of the present invention, the first lumen 302 accommodates flow in a first direction, the first direction being 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, the second direction being from the distal end of the catheter to the proximal end of the catheter. Figure 3B Another schematic 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 conduit 316 is shown. Figure 3B In the embodiment of the present invention, the first lumen 312 accommodates flow in a first direction, the first direction being 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, the second direction being from the distal end of the catheter to the proximal end of the catheter. Figure 3C A third diagrammatic cross section of a cooling element for use in a blood pump 320 for use in a heart having a first lumen portion 322, a second lumen portion 324, a lumen channel 326, and a conduit 328 is shown. Figure 3C In the embodiment of the present invention, the first lumen portion 322 and the second lumen portion 324 are contained within the lumen channel 326. Specifically, the lumen channel 326 is divided into two parts: the first lumen portion 322 including the first lumen and the second lumen portion 324 including the second lumen. The first lumen portion 322 and the second lumen portion 324 can be oriented within the lumen channel 326 in a variety of configurations. For example, Figure 3CAs shown, the first lumen portion 322 and the second lumen portion 324 can each include half of the lumen passage 326. In other embodiments, the first lumen portion 322 can include a larger portion of the lumen passage 326 than the second lumen portion 324. In other embodiments, the first lumen portion 322 can include a smaller portion of the lumen passage 326 than the second lumen portion 324. The lumen passage 326 is contained within the catheter 328. Figure 3C , the first lumen 322 accommodates flow in a first direction, the first direction being from the proximal end of the catheter to the distal end of the catheter 328, and the second lumen 324 accommodates flow in a second direction, the second direction being from the distal end of the catheter to the proximal end of the catheter 328. In a configuration having a Peltier device as a cooling element, the semiconductors of the Peltier device can be similarly oriented in a variety of configurations and relative shapes and sizes. For example, the first semiconductor material of the Peltier device can be configured to abut against the inner surface of the catheter in the shape of the inner surface of the catheter, while the second semiconductor material can be cylindrical and extend along the center of the catheter. The first semiconductor material can also be embedded in the wall of the catheter. In some embodiments, the first semiconductor material can have a surface area larger than the surface area of ​​the second semiconductor material. In other embodiments, the first semiconductor material can have the same surface area as the second semiconductor material. In certain embodiments, the first semiconductor material can have a surface area smaller than the surface area of ​​the second semiconductor material.

[0055] Figure 4A pictorial method 400 for treating myocardial infarction while relieving the workload on the heart is shown. The method 400 first includes a step 402 of introducing a mechanical circulatory support system into the left side of the patient's heart. The mechanical circulatory support system can be a blood pump. The pump of the method 400 includes a cooling element configured in a catheter. Such a cooling element is configured to receive a freezing solution or an electric current, and the cooling element is configured to contact the inner surface of the catheter so that the blood in contact with the outer surface of the catheter is cooled. Subsequently, the physician performing the method 400 performs a step 404, which includes using an onboard motor to actuate the pump. After the pump is actuated, the physician then performs a step 406 of 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 so that the blood reaches systemic temperature. For example, the blood can be systemically cooled for a period of time between about 5 minutes and about 20 minutes. In other embodiments, the period of time is between about 7.5 minutes and about 17.5 minutes. In further implementations, the period of time is between about 10 minutes and about 15 minutes. In some embodiments, the time period for cooling the blood to systemic temperature is about 12.5 minutes. The systemic temperature is selected to reduce or prevent the effects of a heart attack. In some embodiments, the heart attack being treated or prevented is a myocardial infarction, and in some embodiments, the effect of a myocardial infarction being treated or prevented is myocardial scarring. Cooling the blood circulating through the heart slows down the biological processes that lead to myocardial scarring, which reduces and prevents the patient's heart from forming scars after a myocardial infarction. The included cooling element induces hypothermia in the patient, and the support provided by the blood pump helps to reduce the workload on the heart, thereby preventing or reducing the negative side effects of induced hypothermia, including induced arrhythmias.

[0056] Figure 5 An illustrative method 500 is shown for treating myocardial infarction while simultaneously relieving cardiac workload using a mechanical circulatory support system configured with a lumen. The mechanical circulatory support system can be a blood pump. In other embodiments, the mechanical circulatory support system can be an intra-aortic balloon pump, a left heart support system, or a right heart support system. As described above, the lumen of the mechanical circulatory support system of the method can be configured in a variety of geometric shapes. For example, the lumen can extend in a spiral shape in one direction along the length of the catheter, such as Figure 1 In other embodiments, the inner cavity can form a double helix, such as Figure 2As shown. Method 500 first includes step 502 of introducing a blood pump into the left side of the patient's heart. The pump of method 500 includes an inner cavity configured to receive a freezing fluid. As previously described, the freezing solution may include a crystalloid. The crystalloid may be a saline solution (a solution containing 9 grams of sodium chloride per liter of solution), lactated Ringer's solution, 1 / 3 NS2 / 3D5, or glucose. Typically, a solution with the highest heat capacity is selected because such a solution will be able to cool the blood most rapidly without experiencing a temperature rise, thereby keeping the solution in contact with the inner surface of the catheter along both lengths of the catheter. For any geometry, at least a portion of the inner cavity is in contact with the inner surface of the catheter, and the inner cavity is configured to cool the blood in contact with the outer surface of the catheter. The physician performing method 500 then activates the pump using an onboard motor in step 504. While activating the pump, the physician injects a freezing solution into the inner cavity 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 so that the blood reaches systemic temperature. Systemic temperature is selected to reduce or prevent the effects of a heart attack. As previously described, the temperature of the freezing solution is selected so that the blood reaches systemic temperature and becomes cold enough to slow down biological processes that adversely affect the patient after the patient suffers a heart attack. A heart attack may be a myocardial infarction, and the effects of a myocardial infarction may be scarring. Simultaneous cooling and unloading of the heart allows hypothermia to be induced by the cooling element while the blood pump prevents the negative effects of induced hypothermia.

[0057] Figure 6A pictorial method 600 for treating myocardial infarction while relieving the heart load using a mechanical circulatory support system configured with a Peltier device is shown. The mechanical circulatory support system can be a blood pump. The method 600 first includes a step 602 of introducing the blood pump into the left side of the patient's heart. The pump of the method 600 includes a Peltier device. The Peltier device drives heat transfer between two semiconductor materials with different properties. For example, the electron density of the two semiconductor materials can be different. The Peltier device can be configured in a variety of geometric shapes. In particular, the Peltier device includes two semiconductor materials forming a joint, which can be arranged in a variety of different configurations to guide the heat flow in a desired direction and guide it to a desired part of the device. For example, the semiconductor material can be oriented so that the heat flow is guided in a radial direction, or the semiconductor material can be oriented so that the heat flow is guided longitudinally along the length of the catheter. The semiconductor material can be further arranged to allow any configuration of the joint formed by the semiconductor material to be delivered to the current. The joint of the two semiconductor materials with different electron densities can be located at any suitable point along the length of the catheter so as to establish a certain heat distribution along the length of the catheter. In some embodiments, the junction of two semiconductor materials with different electron densities is located at the distal end of the catheter. In other embodiments, the junction of two semiconductor materials with 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 that it is configured to cool the blood in contact with the outer surface of the catheter. After the pump is introduced, the physician then uses the onboard motor to actuate the pump in step 604. While actuating the pump, in step 606, a current flows through the first wire to the junction of the semiconductor material of the Peltier device, cooling the blood in contact with the outer surface of the catheter. The current delivered to the junction of the semiconductor material of the Peltier device can be in the range of between about 0.01 amperes and about 3 amperes. In some embodiments, a current between about 0.1 amperes and about 2 amperes is delivered to the junction of the semiconductor material of the Peltier device. In further embodiments, a current between about 0.5 amperes and 1.5 amperes is delivered to the junction of the semiconductor material of the Peltier device. In certain embodiments, a current of about 1 ampere is delivered to the junction of the semiconductor material of the Peltier device. The specific current flowing through the wire of the Peltier device can be adjusted to produce a certain potential difference at the junction of the semiconductor material, thereby allowing a certain heat distribution and blood cooling rate to be achieved along the catheter. The blood is cooled for a period of time so that the blood reaches the whole body temperature. For example, the blood can be systemically cooled for a period of time between about 5 minutes and about 20 minutes. In other embodiments, the time period is between about 7.5 minutes and about 17.5 minutes. In further embodiments, the time period is between about 10 minutes and about 15 minutes. In some embodiments, the time period for the blood to cool to the whole body temperature is about 12.5 minutes.The whole body temperature is selected to reduce or prevent the effects of a heart attack. A heart attack may be a myocardial infarction, and the effect of a myocardial infarction to be treated may be myocardial scarring.

[0058] The foregoing is merely an illustration of the principles of the present disclosure, and the device may be practiced by other aspects than the described aspects, which are presented for the purpose of illustration and not limitation. It should be understood that although the devices disclosed herein are shown as being used in pumps, they may also be applied to other devices. After reading the present disclosure, various changes and modifications will occur to those skilled in the art. The disclosed features may be implemented in any combination and sub-combination (including multiple subordinate combinations and sub-combinations) with one or more other features described herein. The various features described or illustrated above (including any components thereof) may be combined or integrated in other systems. In addition, some features may be omitted or not implemented.

[0059] Examples of changes, substitutions, and alterations are ascertainable by those skilled in the art and may be made without departing from the scope of the information disclosed herein.All references cited herein are incorporated by reference in their entirety and become a part of this application.

Claims

1. A mechanical circulatory support system for a heart, the system comprising: a pump having a distal end and a proximal end, the pump including a rotor having at least one blade; a pump housing enclosing 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 being configured to contact blood when disposed within a patient's vasculature; and wherein the outer surface of the catheter includes a heat transfer surface configured to cool blood in contact with the outer surface.

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

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

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

5. The mechanical circulatory support system of claim 3, wherein the cooling element is configured to cool the inner surface of the catheter.

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

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

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

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

10. The mechanical circulatory support system of claim 8, wherein the inner cavity has a first proximal opening and a second proximal opening, the first proximal opening being configured as an inlet for a freezing solution, and the second proximal opening serving as an outlet for the freezing solution.

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