Heart assist method and device

• US 3,911,898 A
• Filed: 11/01/1974
• Issued: 10/14/1975
• Est. Priority Date: 04/05/1974
• Status: Expired due to Term

• Current Assignee: Frank A. Leachman Jr
• Original Assignee: Frank A. Leachman Jr
• Inventors: Leachman, Frank A. Jr.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/520,046
• Time in Patent Office: 347 Days
• Field of Search: 3/1.7 23/258.5 128/1D,2.5E,2.5R,419P,419PG,DIG.3
• US Class Current: 600/17
• CPC Class Codes: A61M 60/148 in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices
• CPC Class Codes: A61M 60/152 branching on and drawing blood from a blood vessel
• CPC Class Codes: A61M 60/441 generated by an electromotor
• CPC Class Codes: A61M 60/523 using blood flow data, e.g. from blood flow transducers
• CPC Class Codes: A61M 60/894 Passive valves, i.e. valves actuated by the blood

Abstract

A heart assist device is controlled in a normal mode of operation to counterpulsate with the heart and produce a blood flow waveform corresponding to the flow waveform of the heart being assisted. A blood pump in the device is connected serially between the discharge of a heart ventricle and the vascular system, and during the normal mode of operation, the pump is operated to maintain a programmed pressure at the ventricle discharge during systolic cardiac pulsation. A pressure transducer detects the pressure at the ventricle discharge and a hydraulically powered, closed-loop servomechanism controls the displacement of a piston in an expansible chamber receiving the blood from the ventricle, in such a way that programmed pressure is maintained in the chamber. Means are provided for recording the piston displacement as a function of time during ventricular systole. During diastole, the piston motion is reversed, and servo-controlled to duplicate the recorded displacement waveform while the piston contracts the chamber volume and expels blood into the vascular system. In this way the output blood from waveform produced by the pump during diastole is the same as the output flow waveform produced by the ventricle during the previous systole. In the event that the heart beat stops or becomes severely arrhythmic, the device switches to an autonomous mode of operation and a waveform generator in the pump controls provides an ideal blood flow waveform independent of cardiac pulsations.

Claims

1. A counterpulsation heart assist device comprising:

blood pumping means connectible between a ventricle of the natural heart and the associated vascular system of the body, and including an expansible and contractible pumping chamber for ingesting blood from the ventricle and expelling bloOd into the associated vascular system; and

pumping control means connected with the heart and the pumping means for regulating the pumping means in counterpulsation with the heart and including means for detecting and storing the blood flow waveform produced by the heart during systolic ventricle contractions and means for regulating the expulsion of blood from the pumping chamber to duplicate the stored flow waveform.

2. The heart assist device of claim 1 wherein:

the blood pumping means has a displaceable piston associated with the pumping chamber for expanding and contracting the chamber volume and correspondingly causing blood to be ingested and expelled; and

the pumping control means includes driving means for regulating the piston displacement.

3. A heart assist device as in claim 2 wherein:

the means for detecting and storing is connected to the displaceable piston.

4. A heart assist device as defined in claim 3 wherein:

the means for detecting and storing includes a piston position transducer and waveform recorder connected with the transducer for recording piston displacement.

5. A heart assist device as in claim 4 wherein:

the waveform recorder has a memory programmed on a first-in-first-out basis.

6. A heart assist device as in claim 5 wherein:

the waveform recorder includes a clock-controlled, sequentially addressed memory; and

the pumping control also includes an adjustable clock connected to the memory for adjusting the memory access rate.

7. A heart assist device as defined in claim 1 wherein the pumping control means includes:

pressure responsive means for controlling the expansion of the pumping chamber at a rate establishing a programmed pressure at the ventricle discharge during systole; and

the means for detecting and storing includes memory means for recording the chamber expansion as a function of time.

8. A heart assist device as in claim 7 wherein:

the blood pumping means includes a displaceable piston connected with the pump chamber for causing chamber expansion and contraction;

the pressure responsive means comprises a closed loop servomechanism connected with the piston to control the piston displacement; and

the means for detecting and storing includes a pressure transducer sensing ventricle discharge pressure and providing a pressure signal as an input to the servomechanism.

9. A heart assist device as in claim 7 wherein:

the means for regulating the expulsion of blood from the pumping chamber also includes the closed loop servomechanism connected with the piston in the pumping means.

10. A heart assist device as defined in claim 9 wherein:

the control means includes switching means operated in synchronism with the heart cycle for connecting the input of the servomechanism alternately to receive as inputs the pressure transducer signal and the stored blood flow waveform.

11. A heart assist as defined in claim 1 further including in the pumping control means;

an autonomous pump control having a waveform generator providing a predetermined flow waveform for regulating the puming means independently of the heart pulsations; and

discriminator means responsive to systolic pressure for energizing the autonomous pump control in the presence of severely arrhythmic heart pulsations.

12. A heart assist device as defined in claim 1 wherein:

the pump control means includes programmed means defining the programmed systolic pressure as a constant pressure level throughout the systolic period.

13. A heart assist device as defined in claim 1 wherein:

the pump control means includes programmed means defining the programmed systolic pressure as a variable pressure waveform during the systolic period.

14. A heart assist device as defined in claim 13 wherein:

the programmed means includes an adjustable time-base generator responsive to a heart function for producing the variable pressure waveform in periods of time dependent upoN the heart function.

15. A method of assisting the heart to produce pulsatile blood flow in the vascular system of the body with the blood flow waveform duplicating that of the heart comprising:

maintaining a programmed pressure at the ventricle discharge of the heart during systole;

detecting the blood flow waveform from the heart while the programmed pressure is maintained;

recording the blood flow waveform from the heart as the waveform is detected; and

pumping blood into the vascular system in a controlled manner to duplicate the recorded blood flow waveform.

16. The method of assisting the heart as in claim 15 wherein:

the step of pumping includes the steps of retrieving the recorded flow waveform and driving a blood pump in accordance with the retrieved waveform.

17. The method of assisting the heart as in claim 15 wherein:

the detecting step includes receiving a volume of blood equal to that discharged by the ventricle during systole in a chamber and wherein, the step of pumping comprises expelling the received volume of blood from the chamber during diastole.

18. The method of assisting the heart as defined in claim 15 wherein:

the step of pumping is performed during the diastole immediately following the systole in which the blood flow waveform was detected.

19. The method of assisting the heart as defined in claim 15 including the step of:

synchronizing the step of pumping with the systolic and diastolic periods of the heart by sensing the blood pressure emanating from the ventricle.