Thermistor imbedded therapeutic catheter
Inventors
Curran, Jerald Wayne • Ishikawa, Kiyotake • Hajjar, Roger J.
Assignees
Abiomed Inc • Icahn School of Medicine at Mount Sinai
Publication Number
US-12213771-B2
Publication Date
2025-02-04
Expiration Date
2038-03-21
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Abstract
A system and method for determining native cardiac output of a heart while maintaining operation of an intracardiac blood pump includes determining a current drawn by the pump motor, a blood pressure within the ascending aorta, and a change in the blood temperature based on a thermodilution technique. An intracardiac blood pump positioned in the aorta includes at least one sensor for determining a motor current and blood pressure and a thermistor for determining the change in blood temperature after a precise fluid bolus has been introduced into the vasculature. A processor receives current, pressure, and temperature measurements, and calculates a pump flow output and a total cardiac output from which the native cardiac output is calculated. The native cardiac output and other clinically relevant variables derived from the measurements inform decisions related to continued therapeutic care, including increasing or decreasing cardiac assistance provided by the intracardiac pump.
Core Innovation
The invention provides systems and methods for determining the native cardiac output of a heart while maintaining operation of an intracardiac blood pump. It includes determining the current drawn by the pump motor, the blood pressure within the ascending aorta, and a change in blood temperature using a thermodilution technique. The intracardiac blood pump positioned in the aorta is equipped with sensors to measure motor current, blood pressure, and a thermistor to detect blood temperature changes after a fluid bolus is introduced into the vasculature.
The processor receives signals of current, pressure, and temperature, enabling the calculation of pump flow output, total cardiac output, and the native cardiac output by subtracting pump flow from total flow. The native cardiac output and other clinically relevant variables help inform decisions about continuing therapeutic care, including adjusting cardiac assistance by the pump.
The background highlights the problem that current technologies can only measure total cardiac output and not differentiate native output from mechanical support output while mechanical assistance is active. Existing techniques require stopping or minimizing mechanical support to measure native cardiac output, risking patient safety. Other methods are limited by inaccuracy, procedural risk, additional catheter placement, radiation exposure, or incompatibility with mechanical devices.
The invention addresses these issues by integrating a thermistor in the intracardiac blood pump catheter or sheath to enable thermodilution-based measurement of cardiac outputs while the pump is operating. This allows real-time, continuous, and reproducible measurement of native cardiac output during mechanical circulatory support, providing vital information to clinicians without interrupting mechanical assistance.
Claims Coverage
The patent includes one independent system claim and one independent method claim, each defining key inventive features relating to measurement of cardiac output in a patient using an intracardiac blood pump equipped with sensors and a thermistor.
Intracardiac blood pump system with integrated sensors and thermistor
A system comprising an intracardiac blood pump with a cannula positioned in the patient's aorta, an electrically driven motor, a catheter connected to the cannula, a thermistor for detecting blood temperature in the ascending aorta, a first sensor for measuring motor current changes, a second sensor for measuring blood pressure in the ascending aorta, and a processor receiving signals from these sensors.
Calculation of cardiac outputs and native cardiac output
The processor is configured to calculate pump flow output indicating cardiac assistance based on motor current and blood pressure signals; calculate total cardiac output from thermistor temperature signals, encompassing both mechanical and native outputs; and determine native cardiac output by subtracting pump flow output from the total cardiac output.
Use of thermodilution via fluid bolus with thermistor placement
The thermistor detects changes in blood temperature caused by an introduced bolus of fluid at a different temperature than physiological blood temperature, injected upstream of the pump; the thermistor is positioned near or through the proximal opening of the cannula, enabling measurement of temperature changes as a function of time for cardiac output calculations.
Display and storage of native cardiac output and related cardiac variables
The processor can display native cardiac output and its history over time on a screen, determine a native trend indicating cardiac output improvement, and calculate additional clinically relevant parameters such as global end-diastolic volume, intrathoracic volumes, cardiac index, stroke volume, extravascular lung water, cardiac power output, and global ejection fraction.
Structure and configuration of catheter and sheath with thermistor
The thermistor may be embedded in the catheter or sheath, which may be dual-lumen to accommodate delivery of both the intracardiac blood pump and the thermistor; the system may include a rotor within the cannula, and the motor may be implanted or external with a drive cable through the catheter.
Method for measuring heart performance
A method comprising positioning an intracardiac blood pump in the aorta, operating its motor to pump blood from left ventricle to ascending aorta, detecting blood temperature changes with a thermistor, detecting motor current and aortic pressure with sensors, calculating total cardiac output and pump flow, and determining native cardiac output by subtraction, all during pump operation without interrupting mechanical support.
The inventive features collectively provide an integrated system and method for real-time measurement of native cardiac output during mechanical circulatory support by using sensor signals and thermodilution-based blood temperature detection via a thermistor integrated into the intracardiac blood pump catheter or sheath.
Stated Advantages
Allows measurement of native cardiac output while maintaining continuous mechanical circulatory support, avoiding risks associated with suspension of mechanical assistance.
Provides more accurate and useful physiological information about heart function for clinicians, aiding decisions about patient treatment and weaning from support.
Enables real-time, instantaneous, repeated, and reproducible cardiac output measurements including additional clinically relevant hemodynamic variables.
Reduces procedural risks related to catheter placement and vascular complications by utilizing a thermistor imbedded in the pump catheter or sheath, eliminating the need for additional invasive catheters such as Swan-Ganz.
Improves safety and convenience by integrating sensors and thermistor in a single system, with display and trend analysis for clinical decision support.
Documented Applications
Measurement of total cardiac output, mechanical cardiac output, and native cardiac output in a patient with an intracardiac blood pump.
Real-time monitoring of heart performance and cardiac outputs during mechanical circulatory support without interrupting assistance.
Providing clinicians with real-time data and historical trends to guide decisions on increasing, decreasing, or weaning mechanical cardiac assistance.
Extraction of additional cardiac and pulmonary hemodynamic variables such as global end-diastolic volume, intrathoracic blood volume, extravascular lung water, cardiac index, stroke volume, cardiac power output, and global ejection fraction to guide treatment.
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