Position detection for cyclic support device

Abstract

Methods and apparatus are provided for determining whether a circulation support device is determined to be located in a patient's heart. The method includes: receiving a motor current signal from a motor of the loop support device; receiving a pressure signal from a pressure sensor disposed on the cycle support device; generating a normalized motor current signal based at least in part on the pressure signal; determining a pulsatility of the normalized motor current signal; determining whether the circulation support device is determined to be located in the heart of the patient based at least in part on the pulsatility of the normalized motor current signal; and outputting an alert when it is determined that the circulation support device is not determined to be located in the heart of the patient.

Description

Technical Field

[0001] The present application relates to position detection, and in particular, the present application relates to position detection for circulatory support devices. Background Art

[0002] Fluid pumps, such as blood pumps, are used in the medical field for a variety of applications and purposes. An intravascular blood pump is a pump that can be advanced through a patient's vasculature (i.e., veins and / or arteries) to a location in the patient's heart or elsewhere within the patient's circulatory system. For example, an intravascular blood pump can be inserted via a catheter and positioned to span a heart valve. An intravascular blood pump is typically disposed at the end of a catheter. Once in position, the pump can be used to assist the heart and pump blood through the circulatory system and thereby temporarily reduce the workload of the patient's heart (e.g., to enable the heart to recover after a heart attack). An exemplary intravascular blood pump may be manufactured under the trademark Impala Heart pumps were purchased from ABIOMED (Danvers, MA).

[0003] Such a pump may be positioned, for example, in a heart chamber, such as the left ventricle, to assist the heart. In this case, the blood pump may be inserted and introduced upwards into the left ventricle of the patient's heart via a hollow catheter via the femoral artery. From this location, the blood pump inlet draws blood and the blood pump outlet discharges blood into the aorta. In this way, the function of the heart may be replaced or at least assisted by the operation of the pump.

[0004] The intravascular blood pump is typically connected to a corresponding external heart pump controller, which controls the heart pump (e.g., motor speed) and collects and displays operational data about the blood pump, such as heart signal level, battery temperature, blood flow rate, and tubing integrity. An exemplary heart pump controller may be manufactured under the trademark Auto-Imperial Available from Abiomed Corporation. The controller triggers an alarm when the operating data value drops outside a predetermined value or range (e.g., if a leak, suction and / or pump failure is detected). The controller may include a video display screen on which a graphical user interface configured to display operating data and / or alarms is displayed. Summary of the invention

[0005] Described herein are systems and methods for determining the position of a mechanical circulatory device within a patient's heart.

[0006] In some embodiments of the present technology, a method for determining whether a circulatory support device is properly positioned in a patient's heart is provided. The method includes: receiving a motor current signal from a motor of the circulatory support device; receiving a pressure signal from a pressure sensor disposed on the circulatory support device; generating a normalized motor current signal based at least in part on the pressure signal; determining a pulsatility of the normalized motor current signal; determining whether the circulatory support device is properly positioned in the patient's heart based at least in part on the pulsatility of the normalized motor current signal; and outputting an alarm when it is determined that the circulatory support device is not properly positioned in the patient's heart.

[0007] On the one hand, the method further includes determining a maximum pressure value of the pressure signal within a time window of predetermined length, wherein generating the normalized motor current signal based at least in part on the pressure signal includes generating the normalized motor current signal based at least in part on the maximum pressure value.

[0008] In one aspect, generating the normalized motor current signal based at least in part on the maximum pressure value includes dividing the value of the motor current signal by the maximum pressure value.

[0009] In one aspect, the pressure sensor comprises an optical pressure sensor.

[0010] In one aspect, the method further includes filtering the motor current signal, wherein generating the normalized motor current signal is based at least in part on the filtered motor current signal.

[0011] In one aspect, filtering the motor current signal includes filtering the motor current signal using a bandpass filter.

[0012] In one aspect, the bandpass filter is configured to cut off frequencies below 0.5 Hz and above 5 Hz.

[0013] In one aspect, the bandpass filter is configured to cut off frequencies below 0.65 Hz.

[0014] In one aspect, filtering the motor current signal includes filtering the motor current signal using a low pass filter.

[0015] In one aspect, the method further includes filtering the pressure signal, wherein generating the normalized motor current signal is based at least in part on the filtered pressure signal.

[0016] On the one hand, the method further includes determining a maximum pressure value of the filtered pressure signal within a time window of a predetermined length, wherein generating the normalized motor current signal based at least in part on the filtered pressure signal includes generating the normalized motor current signal based at least in part on the maximum pressure value.

[0017] In one aspect, filtering the pressure signal includes filtering the pressure signal using a low pass filter.

[0018] In one aspect, the low pass filter is configured to cut off frequencies above 5 Hz.

[0019] In one aspect, the method further includes determining a differential pressure signal based at least in part on the pressure signal, wherein determining whether the circulatory support device is properly positioned in the heart of the patient is further based at least in part on the differential pressure signal.

[0020] On the one hand, the method further includes using a time window of predetermined length to determine a minimum pressure value of the pressure signal, and determining that the circulatory support device is not correctly positioned in the heart of the patient when the pulsatility of the normalized motor current signal is greater than a first threshold, the minimum pressure value is less than a second threshold, and the minimum value of the differential pressure signal within the time window is greater than a third threshold, or the maximum value of the differential pressure signal within the time window is greater than a fourth threshold.

[0021] In one aspect, the method further includes determining a pulsatility of the pressure signal, wherein determining whether the circulatory support device is properly positioned in the heart of the patient is further based at least in part on the pulsatility of the pressure signal.

[0022] On the one hand, the method further includes determining whether a minimum pressure value within a time window of a predetermined length of the pressure signal is greater than a third threshold when the pulsatility of the normalized motor current signal is less than a first threshold and the pulsatility of the pressure signal is less than the second threshold, and determining that the circulatory support device is not correctly positioned in the heart of the patient when the minimum pressure value within the time window is less than the third threshold.

[0023] On the one hand, the method further includes determining that the circulatory support device is positioned in the aorta of the heart of the patient when the minimum pressure value within the time window is less than the third threshold, wherein outputting an alarm includes outputting an alarm that the circulatory support device is positioned in the aorta.

[0024] In one aspect, the method further includes filtering the pressure signal, wherein determining the pulsatility of the pressure signal includes determining the pulsatility of the filtered pressure signal.

[0025] In one aspect, filtering the pressure signal includes filtering the pressure signal using a bandpass filter.

[0026] In one aspect, the bandpass filter is configured to cut off frequencies below 0.5 Hz and above 5 Hz.

[0027] In one aspect, the bandpass filter is configured to cut off frequencies below 0.65 Hz.

[0028] On the one hand, the method further includes determining whether a minimum pressure value within a time window of a predetermined length of the pressure signal is greater than a second threshold, and determining that the circulatory support device is correctly positioned in the heart of the patient when the pulsatility of the normalized motor current signal is less than the first threshold and the minimum pressure value within the time window is greater than the second threshold.

[0029] On the one hand, the method further includes determining that the circulatory support device is not properly positioned in the heart of the patient when the pulsatility of the normalized motor current signal is greater than the first threshold and / or when the minimum pressure value within the time window is less than the second threshold.

[0030] In some embodiments of the present technology, a circulatory support device is provided. The circulatory support device includes a rotor, a motor configured to drive the rotor to rotate at one or more speeds, a pressure sensor configured to detect a pressure signal, and at least one controller. The at least one controller is configured to receive a motor current signal from the motor, receive a pressure signal from the pressure sensor, generate a normalized motor current signal based at least in part on the pressure signal, determine a pulsatility of the normalized motor current signal, determine whether the circulatory support device is properly positioned in a patient's heart based at least in part on the pulsatility of the normalized motor current signal, and output an alarm when it is determined that the circulatory support device is not properly positioned in the patient's heart.

[0031] On the one hand, the at least one controller is further configured to determine a maximum pressure value of the pressure signal within a time window of a predetermined length, wherein generating the normalized motor current signal based at least in part on the pressure signal includes generating the normalized motor current signal based at least in part on the maximum pressure value.

[0032] In one aspect, generating the normalized motor current signal based at least in part on the maximum pressure value includes dividing the value of the motor current signal by the maximum pressure value.

[0033] In one aspect, the pressure sensor comprises an optical pressure sensor.

[0034] In one aspect, the at least one controller is further configured to filter the motor current signal, wherein generating the normalized motor current signal is based at least in part on the filtered motor current signal.

[0035] In one aspect, filtering the motor current signal includes filtering the motor current signal using a bandpass filter.

[0036] In one aspect, the bandpass filter is configured to cut off frequencies below 0.5 Hz and above 5 Hz.

[0037] In one aspect, the bandpass filter is configured to cut off frequencies below 0.65 Hz.

[0038] In one aspect, filtering the motor current signal includes filtering the motor current signal using a low pass filter.

[0039] In one aspect, the at least one controller is further configured to filter the pressure signal, wherein generating the normalized motor current signal is based at least in part on the filtered pressure signal.

[0040] On the one hand, the at least one controller is further configured to determine a maximum pressure value of the filtered pressure signal within a time window of a predetermined length, wherein generating the normalized motor current signal based at least in part on the filtered pressure signal includes generating the normalized motor current signal based at least in part on the maximum pressure value.

[0041] In one aspect, filtering the pressure signal includes filtering the pressure signal using a low pass filter.

[0042] In one aspect, the low pass filter is configured to cut off frequencies above 5 Hz.

[0043] In one aspect, the at least one controller is further configured to determine a differential pressure signal based at least in part on the pressure signal, wherein determining whether the circulatory support device is properly positioned in the heart of the patient is further based at least in part on the differential pressure signal.

[0044] On the one hand, the at least one controller is further configured to use a time window of predetermined length to determine a minimum pressure value of the pressure signal, and to determine that the circulatory support device is not correctly positioned in the heart of the patient when the pulsatility of the normalized motor current signal is greater than the first threshold, the minimum pressure value is less than a second threshold, and the minimum value of the differential pressure signal within the time window is greater than a third threshold, or the maximum value of the differential pressure signal within the time window is greater than a fourth threshold.

[0045] In one aspect, the at least one controller is further configured to determine a pulsatility of the pressure signal, wherein determining whether the circulatory support device is properly positioned in the heart of the patient is further based at least in part on the pulsatility of the pressure signal.

[0046] On the one hand, the at least one controller is further configured to determine whether a minimum pressure value within a time window of a predetermined length of the pressure signal is greater than a third threshold when the pulsatility of the normalized motor current signal is less than a first threshold and the pulsatility of the pressure signal is less than the second threshold, and to determine that the circulatory support device is not correctly positioned in the heart of the patient when the minimum pressure value within the time window is less than the third threshold.

[0047] On the one hand, the at least one controller is further configured to determine that the circulatory support device is positioned in the aorta of the heart of the patient when the minimum pressure value within the time window is less than the third threshold, wherein outputting an alarm includes outputting an alarm that the circulatory support device is positioned in the aorta.

[0048] In one aspect, the at least one controller is further configured to filter the pressure signal, wherein determining the pulsatility of the pressure signal comprises determining the pulsatility of the filtered pressure signal.

[0049] In one aspect, filtering the pressure signal includes filtering the pressure signal using a bandpass filter.

[0050] In one aspect, the bandpass filter is configured to cut off frequencies below 0.5 Hz and above 5 Hz.

[0051] In one aspect, the bandpass filter is configured to cut off frequencies below 0.65 Hz.

[0052] On the one hand, the at least one controller is further configured to determine whether a minimum pressure value within a time window of a predetermined length of the pressure signal is greater than a second threshold, and to determine that the circulatory support device is correctly positioned in the heart of the patient when the pulsatility of the normalized motor current signal is less than the first threshold and the minimum pressure value within the time window is greater than the second threshold.

[0053] On the one hand, the at least one controller is further configured to determine that the circulatory support device is not properly positioned in the heart of the patient when the pulsatility of the normalized motor current signal is greater than the first threshold and / or when the minimum pressure value within the time window is less than the second threshold.

[0054] In some embodiments, a method for determining whether a circulatory support device is properly positioned in a patient's heart is provided. The method includes: receiving a motor current signal from a motor of the circulatory support device; filtering the motor current signal using a bandpass filter to generate a filtered motor current signal; receiving a pressure signal from a pressure sensor configured on the circulatory support device; filtering the pressure signal to generate a filtered pressure signal; generating a normalized motor current signal based at least in part on the filtered motor current signal and the filtered pressure signal; determining a pulsatility of the normalized motor current signal; determining a pulsatility of the filtered pressure signal; determining a differential pressure signal based at least in part on the filtered pressure signal; determining that the circulatory support device is not properly positioned in the patient's heart when the pulsatility of the normalized motor current signal is less than a first threshold, the pulsatility of the filtered pressure signal is less than a second threshold, the maximum value of the differential pressure signal within a time window of a predetermined length is greater than a third threshold, or the minimum value of the differential pressure signal within the time window is greater than a fourth threshold; and outputting an alarm when it is determined that the circulatory support device is not properly positioned in the patient's heart. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1A An illustrative circulatory support device that may be used in accordance with some embodiments is shown.

[0056] Figure 1B Description: The patient's heart is located Figure 1A circulatory support device.

[0057] Figure 1C Description contains Figure 1A The ventricular support system of the circulatory support device.

[0058] Figure 2 Description of the invention Figure 1A A display of one or more alerts associated with the position detection of the circulatory support device.

[0059] Figure 3A A truth table representing an algorithm for determining the position of a circulatory support device is illustrated.

[0060] Figure 3B Description Comparison Figure 3A The confusion matrix of the predicted and true positions of the device when the algorithm is used to predict the position of the circulatory support device.

[0061] Figure 4A A truth table illustrating an improved algorithm for determining the position of a circulatory support device in accordance with some embodiments.

[0062] Figure 4B Description Comparison Figure 4A Confusion matrix of the predicted and true positions of the circulatory support device when the improved algorithm is used to predict the position of the circulatory support device.

[0063] Figure 5 A flow chart illustrating a process for determining a position of a circulatory support device in accordance with some embodiments.

[0064] Figures 6A to 6B Instructions for use at different motor speeds Figure 3A A histogram of the classifications made by the algorithm.

[0065] Figures 7A to 7B Instructions for use at different motor speeds Figure 4A A histogram of the classification made by the improved algorithm. DETAILED DESCRIPTION

[0066] A circulatory support device (also referred to herein as a "heart pump" or simply a "pump") is a percutaneous, catheter-based device that provides hemodynamic support to a patient's heart. In order for a heart pump to function properly, it should be properly positioned in the patient's heart, with the inlet portion of the pump positioned in the left ventricle and the outlet portion of the pump positioned in the aorta, thereby spanning the aortic valve of the patient's heart. Figure 1A 1 , the heart pump 110 may include a pigtail 111, an inlet region 112, a cannula 113, a pressure sensor 114, an outlet region 115, a motor housing 116, and / or a catheter 117. The pigtail 111 may help stabilize the heart pump 110 in the patient's heart. It should be appreciated that some embodiments of the heart pump 110 may not include the pigtail 111 and may stabilize the heart pump 110 in other ways or not at all. During operation, blood may be drawn into one or more openings in the inlet region 112, through the cannula 113, and discharged through one or more openings in the outlet region 115 by a motor (not shown) disposed in the motor housing 116. In some implementations, the pressure sensor 114 may include a flexible membrane integrated into the cannula 113. One side of the pressure sensor 114 may be exposed to the blood pressure on the outside of the cannula 113, and the other side may be exposed to the blood pressure within the cannula 113. In some such embodiments, pressure sensor 114 can generate an electrical signal proportional to the difference between the pressure outside cannula 113 and the pressure inside cannula 113. In some embodiments, the pressure difference measured by pressure sensor 114 can be used at least in part to position heart pump 110 within the patient's heart. In some embodiments, pressure sensor 114 is an optical pressure sensor. Catheter 117 can provide a connection between heart pump 110 and one or more other devices of the ventricular support system ( Figure 1C One or more fluid and / or electrical connections between the components (examples of which are shown in ).

[0067] like Figure 1B, the heart pump 110 may be positioned in the patient's heart 120. For example, the heart pump 110 may be percutaneously inserted into the ascending aorta 124 via the femoral artery 122, across the aortic valve 126 and into the left ventricle 128. In other embodiments, the heart pump may be percutaneously inserted into the ascending aorta 124, for example, via the axillary artery 123, across the aortic valve 126 and into the left ventricle 128. In other embodiments, the heart pump may be, for example, directly inserted into the ascending aorta 124, across the aortic valve 126 and into the left ventricle 128. During operation, the heart pump 110 entrains blood from the left ventricle 128 and discharges the blood into the ascending aorta 124. Thus, the heart pump 110 performs some of the work normally performed by the patient's heart 120. The hemodynamic effects of the heart pump include increasing cardiac output, improving coronary blood flow to result in reduced left ventricular end-diastolic pressure, pulmonary capillary wedge pressure, myocardial workload, and oxygen consumption.

[0068] like Figure 1C As shown in FIG. 1 , the heart pump 110 may form part of the ventricular support system 100. The ventricular support system 100 also includes a controller 130 (e.g., an automatic Impala controller from Abiomed Corporation (Danfoss, Mass.)). ), display 140, cleaning subsystem 150, controller cable 160, plug 170, and reset unit 180. As shown, controller 130 includes display 140. Controller 130 monitors and controls the operation of heart pump 110. During operation, cleaning subsystem 150 is configured to deliver cleaning fluid to heart pump 110 through conduit 117 to prevent blood from entering the motor (not shown) within motor housing 116. In some embodiments, the cleaning fluid is a dextrose solution (e.g., 5% dextrose in water with 25 IU / mL or 50 IU / mL of heparin). Connector cable 160 provides electrical connection between heart pump 110 and controller 130. Plug 170 connects conduit 117, cleaning subsystem 150, and connector cable 160. In some embodiments, plug 170 includes a storage device (e.g., memory) configured to store, for example, operating parameters to facilitate transfer of a patient to another controller as needed. Repositioning unit 180 may be used to reposition heart pump 110 in the patient's heart.

[0069] As shown, the cleaning subsystem 150 includes a container 151, a supply line 152, a cleaning cassette 153, a cleaning disc 154, a cleaning tube 155, a check valve 156, a pressure reservoir 157, an infusion filter 158, and a side arm 159. The container 151 can be, for example, a bag or a bottle. The cleaning fluid is stored in the container 151. The supply line 152 provides a fluid connection between the container 151 and the cleaning cassette 153. The cleaning cassette 153 can control how the cleaning fluid in the container 151 is delivered to the heart pump 110. For example, the cleaning cassette 153 can include one or more valves for controlling the pressure and / or flow rate of the cleaning fluid. The cleaning disc 154 can include one or more pressure and / or flow sensors for measuring the pressure and / or flow rate of the cleaning fluid. As shown, the controller 130 includes the cleaning cassette 153 and the cleaning disc 154. The cleaning tube 155 provides a fluid connection between the cleaning disc 154 and the check valve 156. The pressure reservoir 157 provides additional fill volume during cleaning fluid changes. In some embodiments, the pressure reservoir 157 includes a flexible rubber diaphragm that provides additional fill volume through an expansion chamber. The infusion filter 158 helps prevent bacterial contamination and prevents air from entering the catheter 117. The sidewall 159 provides a fluid connection between the infusion filter 158 and the plug 170.

[0070] During operation, the controller 130 may be configured to receive measurements from the pressure sensor 114 and the wash disc 154 and control the operation of the motor (not shown) and the wash cassette 153 within the motor housing 116. As mentioned above, the controller 130 is configured to control and measure the pressure and / or flow rate of the wash fluid via the wash cassette 153 and the wash disc 154. During operation, after exiting the wash subsystem 150 through the side arm 159, the wash fluid passes through a wash chamber (not shown) within the conduit 117 and the plug 170. The sensor cable (not shown), connector cable 160, and plug 170 within the conduit 117 provide electrical connections between the pressure sensor 114 and the controller 130. The motor cable (not shown), connector cable 160, and plug 170 within the conduit 117 provide electrical connections between the motor within the motor housing 116 and the controller 130. During operation, the controller 130 is configured to receive measurements from the pressure sensor 114 via the sensor cable and to control the electrical power delivered via the motor cable to the motor within the motor housing 116. By controlling the power delivered to the motor within the motor housing 116, the controller 130 is operable to control the speed of the motor within the motor housing 116.

[0071] Various modifications may be made to the ventricular support system 100 and one or more of its components. For example, one or more additional sensors may be added to the heart pump 100. In another example, a signal generator may be added to the heart pump 100 to generate a signal indicating the rotational speed of the motor within the motor housing 116. In yet another example, a second pressure sensor may be added near the inlet region 112 of the heart pump 110, and the second pressure sensor may be configured to measure left ventricular blood pressure. In such an embodiment, an additional sensor cable may be disposed within the catheter 117, the connector cable 160, and the plug 170 to provide an electrical connection between the one or more additional sensors and the controller 130. As yet another example, one or more components of the ventricular support system 100 may be separated. For example, the display 140 may be incorporated into another device that communicates with the controller 130 (e.g., wirelessly or through one or more electrical cables).

[0072] As should be understood from the above description, proper positioning of the heart pump 110 across the patient's aortic valve is important to ensure that the heart pump 110 operates properly to support the patient's cardiac function. Because the position of the heart pump 110 within the patient's heart is generally not precisely known during the embedding of the heart pump 110 into the patient's heart or during its operation while in the patient's heart, in some embodiments the position of the heart pump 110 is inferred from sensor information provided by one or more sensors coupled to the heart pump 110 (e.g., a pressure sensor 114, a motor current sensor (not shown), etc.). The sensor information may be provided to a controller 130, which may be configured to determine the position of the heart pump 110 in the patient's heart based at least in part on the sensor information. In some embodiments, the controller 130 may be configured to output an alert to the display 140 to indicate whether the heart pump 110 is in a desired position (e.g., where the inlet region 112 is positioned in the patient's left ventricle and the outlet region 115 is positioned in the patient's aorta), for example Figure 2 . As shown, when the heart pump is properly positioned 261 across the aortic valve, the display 140 may be configured to display an indication 251 that the heart pump is properly positioned. Additionally or alternatively, when it is determined by the controller 130 that the position of the heart pump 110 is not in the desired position, the controller 130 may be configured to output one or more alerts to the display 140 to indicate the incorrect positioning of the heart pump 110. Reporting such alerts may be important to ensure that a medical professional (e.g., a physician) who inserts the heart pump 110 and / or monitors the operation of the heart pump 110 during operation is aware of the incorrect placement and can take corrective action to adjust the position of the heart pump 110 in the patient's heart.

[0073] In some embodiments, controller 130 may be configured to control display 140 to output one of a variety of types of alerts when heart pump 110 is not properly positioned in the patient's heart. Figure 3A, the controller 130 may be configured to determine whether the position of the heart pump is properly positioned (e.g., ok) or improperly positioned (e.g., positioned in the ventricle, positioned in the aorta, unknown) based at least in part on the motor current signal I and the pressure signal P. One or more of the alerts corresponding to an indication that the heart pump position is improperly positioned may be associated with different alert levels corresponding to the risks associated with the current positioning of the heart pump. For example, an indication that the heart pump is positioned in the ventricle or in the aorta may be associated with a higher (e.g., more risky) alert level than an indication that the placement signal (e.g., from an optical pressure sensor) is lower or that the pulsatility of the motor current signal is lower for unknown reasons. It should be appreciated that any suitable number of alert levels may be assigned. Assigning alert levels to pump position alerts may facilitate medical professionals monitoring the operation of the heart pump to appropriately take emergency action when such pump position alerts are provided on the display 140.

[0074] exist Figure 3A In the example shown, the pump position is determined based on three comparisons. Figure 3A As shown in the leftmost row of FIG. , the pulsation of the motor current signal within a predetermined time window (e.g., 2 seconds) is mod_actual With the first threshold I modulation When the heart pump is properly positioned across the aortic valve, the motor current signal sensed from the pump motor fluctuates in a pulsatile manner as the pump motor operates in coordination with the pumping cycle of the patient's heart. Figure 3A As shown in the figure, when the pulsation of the motor current signal I mod_actual Above threshold I modulation When the position of the heart pump is determined to be ok or unknown. The difference between these two types of position determination is based on the pressure sensor signal P min_actual (e.g., from an optical pressure sensor) and a second threshold value P min As shown, when the minimum pressure sensor value P within a predetermined time window (e.g., 2 seconds) of the pressure sensor signal min_actual If the minimum pressure sensor value P within the predetermined time window is greater than the threshold value Pmin, it can be determined that the pump is correctly positioned. min_actual Less than the threshold P min , then it can be determined that the pump position cannot be accurately determined because the stress sensor signal is too low. In such an example, an alert indicating a low pressure signal reading can be output.

[0075] by Figure 3A Continuing with the example shown in mod_actual Below threshold I modulationWhen the position of the heart pump is in an incorrect position (e.g., located in the ventricle, located in the aorta), or unknown, it can be determined. The distinction between these types of position determinations can be further based on the pressure sensor signal P. Similar to the motor current signal, the pressure sensor signal (e.g., from an optical pressure sensor) can fluctuate in a pulsatile manner depending on the position of the pressure sensor in the heart. As shown, when the pulsatility P of the pressure sensor signal within a predetermined time window (e.g., 2 seconds) is greater than the pulsatility P of the pressure sensor signal, the pressure sensor signal can be used to determine whether the heart pump is in an incorrect position (e.g., located in the ventricle, located in the aorta), or unknown. The distinction between these types of position determinations can be further based on the pressure sensor signal P. mod_actual Less than the third threshold P mod When the pulsatility of the pressure signal is determined to be too low to make an accurate determination of the pump position and an unknown alarm is generated. Alternatively, when the pulsatility of the pressure sensor signal within the predetermined time window is P mod_actual When the pressure sensor signal P is greater than the third threshold value Pmod, it is determined that the heart pump is not positioned correctly, because it is positioned in the aorta or in the ventricle. The distinction between these two position determinations is based on the pressure sensor signal P described above. min_actual (e.g., from an optical pressure sensor) and a second threshold value P min As shown, when the minimum pressure sensor value within a predetermined time window (e.g., 2 seconds) of the pressure sensor signal is greater than the threshold value P min However, if the minimum pressure sensor value P within the predetermined time window is min_actual Less than the threshold P min , then it can be determined that the position of the pump is located in the ventricle. Inappropriate positioning of the heart pump in the ventricle or aorta can represent a more serious event for which a medical professional monitoring the operation of the heart pump may want to take corrective action urgently. Therefore, as described above, such alerts can be associated with an alert level that indicates the urgency of the event to the user of the ventricular assist system.

[0076] The inventors have recognized and appreciated that accurately reporting the positioning of the heart pump via an alert provided to a user of a ventricular assist system is important to ensure that a medical professional monitoring the operation of the heart pump takes appropriate action. Although false negatives (e.g., not accurately detecting that the heart pump is in the aorta or ventricle) can be the most critical type of position determination error, generating too many false positives (e.g., detecting that the heart pump is positioned in the aorta or ventricle when it is properly positioned) can also have negative consequences. For example, if such false positives are generated frequently, medical professionals may begin to ignore alerts instead of taking action, as necessary, or instead perform non-essential medical procedures (e.g., using ultrasound to image the heart) when the pump is in fact properly positioned. Additionally, because aortic and / or ventricular alerts may be associated with higher alert levels, patients may become concerned or nervous when such alerts are displayed frequently, leading to a negative patient experience.

[0077] Figure 3B Show comparison based on Figure 3AThe confusion matrix of the predicted position of the heart pump (horizontal axis) and the actual position of the heart pump verified by a human operator (vertical axis) using the algorithm and metrics shown in FIG. Figure 3A The algorithm performs error-free position detection relative to the human marker data, then all values ​​will be along Figure 3B The confusion matrix of is placed diagonally from top left to bottom right. However, as shown, applying Figure 3A The algorithm results in a significant number (16.2%) of false positive mid-aortic alerts and, to a lesser extent, a large number of false positive unknown low pulse and position signal low alerts when the heart pump is in fact properly positioned. As discussed above, generating false positive alerts when the heart pump is properly positioned has multiple negative consequences. To this end, some embodiments are directed to techniques for improving the accuracy of heart pump position estimation based on motor current and pressure sensor signals.

[0078] The inventors have recognized and appreciated that Figure 3A The algorithm schematically illustrated in makes multiple adjustments to improve the accuracy of heart pump position detection. In some embodiments, all adjustments described herein may be used, while in other embodiments, only one or a subset of the adjustments may be used, and the embodiments of the present disclosure are not limited in this respect.

[0079] The first adjustment involves normalizing the motor current signal, and using the normalized motor current signal rather than the raw (or originally unnormalized) motor current signal to determine the motor current pulsatility within a predetermined time window (e.g., 2 seconds). In some embodiments, the normalization of the motor current signal is based at least in part on a pressure sensor signal (e.g., as determined from an optical pressure sensor). The inventors have recognized and appreciated that the motor current signal is more pulsatile at higher pressures, and less pulsatile at lower pressures, even when the heart pump is properly positioned across the aortic valve. By normalizing the motor current signal based on the measured pressure sensor signal to take into account the actual pressure value of the patient, it enables the motor current signal to more accurately reflect the patient's true condition before evaluating the pulsatility of the motor current signal.

[0080] The normalization factor based on the measured pressure sensor signal and used to normalize the motor current signal can be determined in any suitable manner. In some embodiments, the normalization factor corresponds to the pulsatility of the pressure sensor signal measured within a predetermined time window. In other embodiments, the normalization factor corresponds to the mean arterial pressure (MAP) measured within a predetermined time window of the pressure sensor signal. In other embodiments, the normalization factor corresponds to the maximum pressure value P measured within the predetermined time window of the pressure sensor signal. max In some examples, the maximum pressure value P maxMAP can be used as a normalization factor because it is more tolerant to the location of the heart pump. For example, using MAP as a normalization factor assumes that the pressure sensor positioned on the heart pump is in the aorta. However, if the pressure sensor is not positioned in the aorta, then MAP will not be accurate. In contrast, even when the pressure sensor is not positioned in the aorta (e.g., the pressure sensor is positioned in the ventricle), MAP will not be accurate. max will represent the true maximum pressure during systole.

[0081] like Figure 4A As shown in FIG. 1 , in some embodiments, the motor current signal (or a processed version of the motor current signal) is divided by the maximum pressure signal P determined within a time window of a predetermined length (e.g., 2 seconds). max The ripple property I of the resulting normalized motor current signal is then used at least in part to determine the motor current signal. mod / P max (optionally multiplied by a scaling factor of 100) to determine whether the heart pump is properly positioned in the patient's heart.

[0082] The inventors have recognized and appreciated that the motor current signal and / or the pressure sensor signal may drift over time. Figure 3A In a second adjustment of the algorithm, the motor current signal (or a processed version of the motor current signal) and / or the pressure sensor signal (or a processed version of the pressure sensor signal) are filtered before being used to estimate the pump position. In some embodiments, the motor current signal is filtered, and then the filtered motor current signal is normalized using one or more of the normalization techniques described herein.

[0083] Any suitable filter may be applied to filter the motor current signal and / or the pressure sensor signal. The inventors have recognized and appreciated that respiratory effects, coughing, and / or other factors may contribute to the calculated pulsatility of the motor current signal and / or the pressure sensor signal. To adjust for such factors, a bandpass filter configured to perform baseline correction of the corresponding signal may be used to filter one or both of the motor current signal and the pressure sensor signal. Any suitable cutoff frequency may be used. In some embodiments, the bandpass filter may have a low-end cutoff of 0.5 Hz and a high-end cutoff of 5 Hz. In other embodiments, the bandpass filter may have a low-end cutoff of 0.65 Hz. In some embodiments, the cutoff frequency may be selected to include a typical range of heart rates observed by patients who can use a heart pump. In some embodiments, the pressure sensor signal may be filtered, and a normalized motor current may be generated based at least in part on the filtered pressure sensor signal. For example, a normalization factor (e.g., MAP, Pmax, etc.) may be determined based on the filtered pressure sensor signal. Any suitable filter may be applied to filter the pressure sensor signal. For example, in some embodiments, a low-pass filter is used to filter the pressure sensor signal. Any suitable cutoff frequency can be used for the low pass filter. For example, in some embodiments, the low pass filter has a cutoff frequency of 5 Hz. In some embodiments, the pressure sensor signal can be filtered differently depending on the pressure metric that is desired to be calculated from the filtered pressure sensor signal. For example, to calculate the pulsatility of the pressure sensor signal, the pressure sensor signal can first be filtered using a band pass filter (as described above), and to calculate the maximum pressure value P max Or minimum pressure value P min_actual (or any other absolute parameter, for example), the pressure sensor signal may first be filtered using a low pass filter. In this way, one or more filtered motor current signals and / or pressure sensor signals may be generated based on the desired corresponding motor current and / or pressure metrics to be determined.

[0084] The inventors have recognized and appreciated that at higher pump speeds, when the pump is doing most of the pumping of the heart and therefore the valves are not opening much, there is a separation of the aortic signal from the ventricular signal to result in a weakened left ventricular signal that looks similar to a suction condition. In such scenarios, because it is not possible to determine whether a suction condition has occurred or whether the heart pump is in a desired position, in some embodiments, when it is determined that the heart pump position is not properly positioned (e.g., positioned in the aorta or positioned in the ventricle) and / or when it is determined that the pump position is unknown, a decision is made to Figure 3A A third adjustment of the algorithm performs one or more additional checks.

[0085] According to one such additional check, a differential pressure signal dP across the aortic valve is determined based at least in part on the pressure sensor signal. Figures 1A to 1CAs described, the heart pump may include a pressure sensor (e.g., an optical pressure sensor) configured to detect the patient's aortic pressure when the heart pump is properly positioned in the patient's heart. The heart pump may not include another pressure sensor configured to detect the patient's ventricular pressure. In such examples, the differential pressure signal dP may be indirectly determined using the measured aortic pressure, the measured motor current, and a lookup table that maps the motor current value to the dP value of the heart pump. In some embodiments, the left ventricular pressure (LVP) may also be determined indirectly. For example, the LVP may be determined using the measured aortic pressure signal and the known pressure difference dP across the aortic valve. The decoupling of the dP and LVP signals suggests that a suction event has occurred and an alert indicating the suction event may be displayed via the display 140 to inform a medical professional monitoring the operation of the heart pump to move the heart pump to correct the suction condition.

[0086] In some embodiments, one or more additional checks include determining the minimum value dP of the dP signal within a time range of a predetermined length (eg, 2 seconds). min In some embodiments, one or more additional checks include determining the maximum value dP of the dP signal within a time range of a predetermined length (e.g., 2 seconds). max Appropriate alerts may be generated based on one or more additional checks to further reduce false positives regarding the positioning of the heart pump within the aorta or ventricle.

[0087] Figure 4B Show comparison based on Figure 4A Confusion matrix of the predicted position of the heart pump (horizontal axis) and the actual position of the heart pump verified by a human operator (vertical axis) using the algorithm and metrics presented in FIG. Figure 3B Compared to the confusion matrix shown in , it can be observed that the number of false positive aortic alerts has been substantially reduced ( Figure 4B 0.4% of Figure 3B Moderate improvements were also observed in other cases. For example, the false alarm rate for placing a signal low alert was reduced from 16.2% using Figure 3A 7.9% of the algorithm is reduced to using Figure 4A It is noteworthy that the false negative rate does not change substantially for two conditions that are indicative of improper placement of the heart pump in the heart: in the aorta and in the ventricle.

[0088] Figure 55 is a flow chart of process 500 of an improved position detection technique according to some embodiments. In act 502, a motor current signal associated with an operating state of a motor within a heart pump is received. Process 500 then proceeds to act 504, where the received motor current signal is filtered (e.g., using a bandpass filter as described above). In act 506, a pressure sensor signal is received (e.g., from an optical pressure sensor positioned on the heart pump). Process 500 then proceeds to act 508, where the received pressure sensor signal is filtered (e.g., using a low pass filter and / or bandpass filter as described above). Process 500 then proceeds to act 510, where a normalized motor current signal is generated using the filtered motor current signal and the filtered pressure signal. For example, as described above, the value of the filtered motor current signal may be divided by the maximum pressure P determined within a predetermined time window of the pressure sensor signal. max .

[0089] The process 500 then proceeds to act 512, where the pulsatility of the normalized motor current signal is determined and compared to a first threshold. If it is determined in act 512 that the pulsatility of the normalized motor current signal is less than the first threshold, then the process 500 then proceeds to act 514, where it is determined whether the measured minimum pressure value from the pressure sensor signal is greater than a second threshold. If it is determined in act 514 that the minimum pressure value is greater than the second threshold, then the process 500 proceeds to act 516, where it is determined that the position of the heart pump is ok. If it is determined in act 514 that the minimum pressure value is less than the second threshold, then the process 500 proceeds to act 518, where it is determined that the position of the heart pump is uncertain. After determining that the position of the heart pump is uncertain, one or more additional checks may be performed to assess whether the pump position is ok despite the low pressure measurement, as described above.

[0090] If it is determined in act 512 that the pulsatility of the motor current signal is less than the first threshold, then process 500 proceeds to act 520, where the pulsatility of the filtered pressure signal is determined and compared to the third threshold. If it is determined in act 520 that the pulsatility of the filtered pressure sensor signal is not greater than the third threshold, then process 500 proceeds to act 522, where it is determined that the position of the heart pump is uncertain. Although the pulsatility of the pressure signal is low, one or more additional checks (as described above) may be performed to determine whether the pump is correctly positioned. If it is determined in act 520 that the pulsatility of the pressure signal is greater than the third threshold, then process 500 proceeds to act 524, where it is determined whether the measured minimum pressure value from the pressure sensor signal is greater than the fourth threshold. If it is determined in act 524 that the minimum pressure value is greater than the fourth threshold, then process 500 proceeds to act 526, where it is determined that the position of the heart pump is in the aorta. As described above, in some embodiments, one or more additional checks are performed when it is determined that the pump position is located in the aorta to avoid generating false alarms when the pump is correctly positioned. If it is determined in act 524 that the minimum pressure value is less than the fourth threshold, process 500 proceeds to act 528, where it is determined that the position of the heart pump is located in the ventricle. After determining that the position of the heart pump is located in the ventricle, one or more additional checks can be performed to avoid false alarms when the pump is correctly positioned.

[0091] The first, second, third, and fourth thresholds may be set in any suitable manner. In some embodiments, at least some of the thresholds are set based on experimental data describing the types of errors produced. Fig. 6A Go to B to show how to use Figure 3A . The vertical axis represents the number of classifications and the horizontal axis represents the normalized motor current value. The motor of the heart pump can be configured to operate at one of a plurality of fixed speeds (e.g., designated as P1 to P9), and the classifications generated at different motor speeds can also be different. Figures 6A to 6B Contains separate bar graphs for each motor speed P1 to P9. As discussed above, for improving Figure 3A The motivating factor for the algorithm is to reduce false positives where the algorithm determines that the heart pump is positioned in the aorta when in fact the heart pump is properly positioned across the aortic valve. Figures 6A to 6B As shown in , one way to conceptualize a solution to this problem is to determine a threshold that separates examples where false positives are classified as in the aorta by the algorithm and examples where true positives are classified as in the aorta by the algorithm. Figures 6A to 6B For each of the motor speeds P1 to P9 represented in FIG. 1 , a dashed line representing the threshold value that best separates the two populations described above is shown. Figures 6A to 6BIt is understood that at many motor current speeds, the "not in aorta" and "definitely in aorta" classifications overlap substantially to make determining an appropriate threshold difficult. The overlap is more pronounced at faster motor speeds (e.g., P8 to P9), where the number of false positives classified in the aorta increases relative to slower motor speeds.

[0092] Fig. 7A Go to B to show how to use Figure 4A The distribution of different classifications made by the improved algorithm is shown in the histogram. Similar to Figures 6A to 6B The bar graph shown in FIG. 1 shows a threshold designed to separate the non-aortic classification and the positive classification of each of the motor speeds P1 to P9 at Figures 7A to 7B Indicated as a dotted line. Figures 7A to 7B It is appreciated that the improved algorithm for determining heart pump position according to some embodiments produces substantially non-overlapping distributions of not classified in the aorta and classified in the aorta. At faster motor speeds (e.g., P8 to P9), although the number of false positives classified in the aorta remains greater than at slower motor speeds, its distribution as a function of normalized motor current is separated from the distribution of classified in the aorta, which enables drawing appropriate thresholds between the two populations for different motor speeds (e.g., Figure 5 The "first threshold" described in action 512 or Figure 4A The algorithm shown in I mod_norm_thresh ) to separate them.

[0093] Therefore, the embodiments of the present technology and the several aspects described in the present disclosure have been described, and it should be understood that a person of ordinary skill in the art should be easy to think of various substitutions, modifications and improvements. Such substitutions, modifications and improvements are expected to be within the spirit and scope of the present technology described herein. For example, a person of ordinary skill in the art will easily envision other components and / or structures for performing functions and / or obtaining one or more of the results and / or advantages described herein, and each of such changes and / or modifications is considered to be within the scope of the embodiments described herein. A person of ordinary skill in the art will recognize or be able to determine many equivalents of the specific embodiments described herein using only routine experiments. Therefore, it should be understood that the above embodiments are presented for example only, and the invention embodiments can be practiced in other ways other than the specifically described ways within the scope of the attached claims and their equivalents. In addition, if the features, systems, articles, materials, sets and / or methods described herein are not inconsistent with each other, any combination of two or more such features, systems, articles, materials, sets and / or methods is included within the scope of the present disclosure.

[0094] The embodiments described above may be implemented in any of many ways. One or more aspects and embodiments of the present disclosure relating to the performance of a process or method may utilize program instructions that can be executed by a device (e.g., a computer, a processor, or other device) to perform or control the performance of a process or method. In this regard, various inventive concepts may be embodied as a computer-readable storage medium (or multiple computer-readable storage media) (e.g., a circuit configuration in a computer memory, one or more floppy disks, compact disks, optical disks, tapes, flash memory, field programmable gate arrays, or other semiconductor devices, or other tangible computer storage media), which is encoded using one or more programs that, when executed on one or more computers or other processors, perform methods that implement one or more of the various embodiments described above. The computer-readable medium may be transportable so that the program stored thereon may be loaded onto one or more different computers or other processors to implement multiple of the aspects described above. In some embodiments, the computer-readable medium may be a non-transitory medium.

[0095] The above-described embodiments of the present technology may be implemented in any of many ways. For example, the embodiments may be implemented using hardware, software, or a combination thereof. When implemented in software, the software code may be executed on any suitable processor or set of processors, whether provided in a single computer or distributed between multiple computers. It should be understood that any component or set of components that perform the functions described above may generally be considered to be a controller that controls the functions described above. The controller may be implemented in many ways, such as using dedicated hardware or using general-purpose hardware (e.g., one or more processors) that is programmed using microcode or software to perform the functions stated above and may be implemented in a combination of ways when the controller corresponds to multiple components of a system.

[0096] Furthermore, it should be appreciated that a computer may be embodied in any of a number of forms, such as, by way of non-limiting example, a rack-mount computer, a desktop computer, a laptop computer, or a tablet computer. Additionally, a computer may be embedded in a device not generally regarded as a computer but having suitable processing capabilities, including a personal digital assistant (PDA), a smart phone, or any other suitable portable or fixed electronic device.

[0097] In addition, a computer may have one or more input and output devices. These devices may be used to present a user interface, among other things. Examples of output devices that may be used to provide a user interface include a printer or display screen for visually presenting output or a speaker or other sound generating device for audibly presenting output. Examples of input devices that may be used for a user interface include a keyboard and a pointing device, such as a mouse, a touch pad, and a digitizing panel. As another example, a computer may receive input information through speech recognition or in other audible formats.

[0098] Such computers may be interconnected by one or more networks in any suitable form, including local or wide area networks (e.g., enterprise networks) and intelligent networks (IN) or the Internet. Such networks may be based on any suitable technology and may operate according to any suitable protocol and may include wireless networks, wired networks, or fiber optic networks.

[0099] Furthermore, as described, some aspects may be embodied as one or more methods. The actions performed as part of the method may be ordered in any suitable manner. Thus, embodiments may be constructed in which the actions are performed in an order different from that described, which may include performing some actions simultaneously, even though shown as sequential actions in illustrative embodiments.

[0100] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0101] Unless explicitly indicated to the contrary, the definite articles "a" and "an" as used herein in the specification and claims should be understood to mean "at least one".

[0102] The phrase "and / or" as used herein in the specification and claims should be understood to mean "either or both" of the elements so combined, i.e., elements that appear combined in some cases and separated in other cases. Multiple elements listed using "and / or" should be interpreted in the same manner, i.e., "one or more" of the elements are so combined. In addition to the elements specifically identified by the "and / or" clause, other elements may optionally be present, whether or not related to the specifically identified elements. Thus, as a non-limiting example, a reference to "A and / or B", when used in conjunction with open language such as "comprising", may refer to only A (optionally including elements other than B) in one embodiment; to only B (optionally including elements other than A) in another embodiment; to both A and B (optionally including other elements) in yet another embodiment, etc.

[0103] As used herein in the specification and claims, the phrase "at least one" referring to a list of one or more elements should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed in the list of elements and not excluding any combination of elements in the list of elements. This definition also allows that in addition to the elements specifically identified in the list of elements referenced by the phrase "at least one", elements related or unrelated to the elements specifically identified may optionally be present. Thus, as a non-limiting example, "at least one of A and B" (or equivalently, "at least one of A or B", or equivalently, "at least one of A and / or B") may refer in one embodiment to at least one (optionally including more than one) A, and no B (and optionally including elements other than B); in another embodiment, to at least one (optionally including more than one) B, and no A (and optionally including elements other than A); in yet another embodiment, to at least one (optionally including more than one) A and at least one (optionally including more than one) B (which optionally includes other elements), etc.

[0104] In addition, the phrases and terms used herein are for description and should not be considered as limiting. The use of "includes," "comprising," or "having," "containing," "involving," and variations thereof herein is meant to encompass the items listed thereafter and their equivalents and additional items.

[0105] In the claims and the foregoing description, all transitional phrases such as "including," "comprising," "carrying," "having," "containing," "involving," "having," "consisting of," and the like shall be understood as open-ended, i.e., meaning including but not limited to. The transitional phrases "consisting of" and "consisting essentially of" shall be closed or semi-closed transitional phrases, respectively.

[0106] The use of ordinal numbers such as "first", "second", "third", etc. in the claims to modify claim elements does not itself imply any priority, precedence or order of one claim element over another claim element or the temporal order of the actions of the method performed therein, but is merely used as a mark to distinguish one claim element with a specific name from another element with the same name (but using an ordinal number) to distinguish the claim elements.

Claims

1. A method of determining whether a circulatory support device is properly positioned in a patient's heart, the method comprising: receiving a motor current signal from a motor of the circulatory support device; receiving a pressure signal from a pressure sensor disposed on the circulatory support device; generating a normalized motor current signal based at least in part on the pressure signal; determining a pulsatility of the normalized motor current signal; determining whether the circulatory support device is properly positioned in the heart of the patient based at least in part on the pulsatility of the normalized motor current signal; and An alarm is output when it is determined that the circulatory support device is not properly positioned in the heart of the patient.

2. The method according to claim 1, further comprising: determining a maximum pressure value of the pressure signal within a time window of a predetermined length, Wherein generating the normalized motor current signal based at least in part on the pressure signal includes generating the normalized motor current signal based at least in part on the maximum pressure value. 3 . The method of claim 2 , wherein generating the normalized motor current signal based at least in part on the maximum pressure value comprises dividing a value of the motor current signal by the maximum pressure value. The method of claim 1 , wherein the pressure sensor comprises an optical pressure sensor.

5. The method according to claim 1, further comprising: filtering the motor current signal, Wherein generating the normalized motor current signal is based at least in part on the filtered motor current signal. The method of claim 5 , wherein filtering the motor current signal comprises filtering the motor current signal using a bandpass filter. The method of claim 6 , wherein the bandpass filter is configured to cut off frequencies below 0.5 Hz and above 5 Hz. The method of claim 7 , wherein the bandpass filter is configured to cut off frequencies below 0.65 Hz. 9 . The method of claim 5 , wherein filtering the motor current signal comprises filtering the motor current signal using a low pass filter.

10. The method according to claim 1, further comprising: filtering the pressure signal, Wherein generating the normalized motor current signal is based at least in part on the filtered pressure signal.

11. The method according to claim 10, further comprising: determining a maximum pressure value of the filtered pressure signal within a time window of predetermined length, Wherein generating the normalized motor current signal based at least in part on the filtered pressure signal includes generating the normalized motor current signal based at least in part on the maximum pressure value. 12 . The method of claim 10 , wherein filtering the pressure signal comprises filtering the pressure signal using a low pass filter. The method of claim 12 , wherein the low pass filter is configured to cut off frequencies above 5 Hz.

14. The method of claim 1, further comprising: determining a differential pressure signal based at least in part on the pressure signal, Wherein determining whether the circulatory support device is properly positioned in the heart of the patient is further based at least in part on the differential pressure signal.

15. The method according to claim 14, further comprising: using a time window of predetermined length to determine a minimum pressure value of the pressure signal; and It is determined that the circulatory support device is not properly positioned in the heart of the patient when: The pulsatility of the normalized motor current signal is greater than a first threshold; The minimum pressure value is less than a second threshold value; and The minimum value of the differential pressure signal within the time window is greater than a third threshold or the maximum value of the differential pressure signal within the time window is greater than a fourth threshold.

16. The method of claim 1, further comprising: determining the pulsatility of the pressure signal, Wherein determining whether the circulatory support device is properly positioned in the heart of the patient is further based at least in part on the pulsatility of the pressure signal.

17. The method according to claim 16, further comprising: When the pulsatility of the normalized motor current signal is less than a first threshold and the pulsatility of the pressure signal is less than the second threshold, determining whether a minimum pressure value within a time window of a predetermined length of the pressure signal is greater than a third threshold; and When the minimum pressure value within the time window is less than the third threshold, it is determined that the circulatory support device is not properly positioned in the heart of the patient.

18. The method according to claim 17, further comprising: The circulatory support device is determined to be positioned in the aorta of the heart of the patient when the minimum pressure value within the time window is less than the third threshold value, wherein Outputting an alarm includes outputting an alarm that the circulatory support device is positioned in the aorta.

19. The method of claim 16, further comprising: filtering the pressure signal, Wherein determining the pulsatility of the pressure signal comprises determining the pulsatility of the filtered pressure signal.

20. The method of claim 19, wherein filtering the pressure signal comprises filtering the pressure signal using a bandpass filter.

21. The method of claim 20, wherein the bandpass filter is configured to cut off frequencies below 0.5 Hz and above 5 Hz.

22. The method of claim 21, wherein the bandpass filter is configured to cut off frequencies below 0.65 Hz.

23. The method of claim 1, further comprising: determining whether a minimum pressure value within a time window of a predetermined length of the pressure signal is greater than a second threshold; and The circulatory support device is determined to be properly positioned in the heart of the patient when the pulsatility of the normalized motor current signal is less than the first threshold and the minimum pressure value within the time window is greater than the second threshold.

24. The method of claim 23, further comprising: When the pulsatility of the normalized motor current signal is greater than the first threshold and / or when the minimum pressure value within the time window is less than the second threshold, it is determined that the circulatory support device is not properly positioned in the heart of the patient.

25. A circulatory support device comprising: Rotor; a motor configured to drive the rotor to rotate at one or more speeds; a pressure sensor configured to detect a pressure signal; and At least one controller configured to: receiving a motor current signal from the motor; receiving a pressure signal from the pressure sensor; generating a normalized motor current signal based at least in part on the pressure signal; determining a pulsatility of the normalized motor current signal; determining whether the circulatory support device is properly positioned in a patient's heart based at least in part on the pulsatility of the normalized motor current signal; and An alarm is output when it is determined that the circulatory support device is not properly positioned in the heart of the patient.

26. The circulatory support device of claim 25, wherein the at least one controller is further configured to: determining a maximum pressure value of the pressure signal within a time window of a predetermined length, Wherein generating the normalized motor current signal based at least in part on the pressure signal includes generating the normalized motor current signal based at least in part on the maximum pressure value.

27. The circulatory support device of claim 26, wherein generating the normalized motor current signal based at least in part on the maximum pressure value comprises dividing a value of the motor current signal by the maximum pressure value.

28. The circulatory support device of claim 25, wherein the pressure sensor comprises an optical pressure sensor.

29. The circulatory support device of claim 25, wherein the at least one controller is further configured to: filtering the motor current signal, Wherein generating the normalized motor current signal is based at least in part on the filtered motor current signal.

30. The circulatory support device of claim 29, wherein filtering the motor current signal comprises filtering the motor current signal using a bandpass filter.

31. The circulatory support device of claim 30, wherein the bandpass filter is configured to cut off frequencies below 0.5 Hz and above 5 Hz.

32. The circulatory support device of claim 31 , wherein the bandpass filter is configured to cut off frequencies below 0.65 Hz.

33. The circulatory support device of claim 29, wherein filtering the motor current signal comprises filtering the motor current signal using a low pass filter.

34. The circulatory support device of claim 25, wherein the at least one controller is further configured to: filtering the pressure signal, Wherein generating the normalized motor current signal is based at least in part on the filtered pressure signal.

35. The circulatory support device of claim 34, wherein the at least one controller is further configured to: determining a maximum pressure value of the filtered pressure signal within a time window of predetermined length, Wherein generating the normalized motor current signal based at least in part on the filtered pressure signal includes generating the normalized motor current signal based at least in part on the maximum pressure value.

36. The circulatory support device of claim 35, wherein filtering the pressure signal comprises filtering the pressure signal using a low pass filter.

37. The circulatory support device of claim 36, wherein the low pass filter is configured to cut off frequencies above 5 Hz.

38. The circulatory support device of claim 25, wherein the at least one controller is further configured to: determining a differential pressure signal based at least in part on the pressure signal, Wherein determining whether the circulatory support device is properly positioned in the heart of the patient is further based at least in part on the differential pressure signal.

39. The circulatory support device of claim 38, wherein the at least one controller is further configured to: using a time window of predetermined length to determine a minimum pressure value of the pressure signal; and It is determined that the circulatory support device is not properly positioned in the heart of the patient when: The pulsatility of the normalized motor current signal is greater than a first threshold; The minimum pressure value is less than a second threshold value; and The minimum value of the differential pressure signal within the time window is greater than a third threshold or the maximum value of the differential pressure signal within the time window is greater than a fourth threshold.

40. The circulatory support device of claim 25, wherein the at least one controller is further configured to: determining the pulsatility of the pressure signal, Wherein determining whether the circulatory support device is properly positioned in the heart of the patient is further based at least in part on the pulsatility of the pressure signal.

41. The circulatory support device of claim 40, wherein the at least one controller is further configured to: determining whether a minimum pressure value within a time window of a predetermined length of the pressure signal is greater than a third threshold when the pulsatility of the normalized motor current signal is less than a first threshold and the pulsatility of the pressure signal is less than the second threshold; and It is determined that the circulatory support device is not properly positioned in the heart of the patient when the minimum pressure value within the time window is less than the third threshold.

42. The circulatory support device of claim 41, wherein the at least one controller is further configured to: The circulatory support device is determined to be positioned in the aorta of the heart of the patient when the minimum pressure value within the time window is less than the third threshold value, wherein Outputting an alarm includes outputting an alarm that the circulatory support device is positioned in the aorta.

43. The circulatory support device of claim 40, wherein the at least one controller is further configured to: filtering the pressure signal, Wherein determining the pulsatility of the pressure signal comprises determining the pulsatility of the filtered pressure signal.

44. The circulatory support device of claim 43, wherein filtering the pressure signal comprises filtering the pressure signal using a bandpass filter.

45. The circulatory support device of claim 44, wherein the bandpass filter is configured to cut off frequencies below 0.5 Hz and above 5 Hz.

46. ​​The circulatory support device of claim 45, wherein the bandpass filter is configured to cut off frequencies below 0.65 Hz.

47. The circulatory support device of claim 25, wherein the at least one controller is further configured to: determining whether a minimum pressure value within a time window of a predetermined length of the pressure signal is greater than a second threshold; and The circulatory support device is determined to be properly positioned in the heart of the patient when the pulsatility of the normalized motor current signal is less than the first threshold and the minimum pressure value within the time window is greater than the second threshold.

48. The circulatory support device of claim 47, wherein the at least one controller is further configured to: The circulatory support device is determined to be improperly positioned in the heart of the patient when the pulsatility of the normalized motor current signal is greater than the first threshold and / or when the minimum pressure value within the time window is less than the second threshold.

49. A method of determining whether a circulatory support device is properly positioned in a patient's heart, the method comprising: receiving a motor current signal from a motor of the circulatory support device; filtering the motor current signal using a bandpass filter to produce a filtered motor current signal; receiving a pressure signal from a pressure sensor disposed on the circulatory support device; filtering the pressure signal to produce a filtered pressure signal; generating a normalized motor current signal based at least in part on the filtered motor current signal and the filtered pressure signal; determining a pulsatility of the normalized motor current signal; determining a pulsatility of the filtered pressure signal; determining a differential pressure signal based at least in part on the filtered pressure signal; It is determined that the circulatory support device is not properly positioned in the heart of the patient when: (i) the pulsatility of the normalized motor current signal is less than a first threshold; (ii) the pulsatility of the filtered pressure signal is less than a second threshold; (iii) the maximum value of the differential pressure signal within a time window of a predetermined length is greater than a third threshold value; or (iv) a minimum value of the differential pressure signal within the time window is greater than a fourth threshold; and An alarm is output when it is determined that the circulatory support device is not properly positioned in the heart of the patient.

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