Heart assist device

• US 3,911,897 A
• Filed: 04/05/1974
• 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:
  US05/458,535
• Time in Patent Office: 557 Days
• Field of Search: 128/1D,2.5E,2.5R,419P,419PG 3/1,DIG.2 417/12,38 23/258.5
• 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 60/258 Piston pumps
• CPC Class Codes: A61M 60/427 the force acting on the blood contacting member being hydraulic or pneumatic
• CPC Class Codes: A61M 60/531 using blood pressure data, e.g. from blood pressure sensors
• CPC Class Codes: A61M 60/569 synchronous with the native heart beat
• 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 copulsate 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 discharge and controls the pump through a hydraulically powered, closed-loop servomechanism. 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 heart assist device comprising:

blood pumping means connectible between a ventricle of the natural heart and the associated vascular system of the body; and

pumping control means connected with heart and the pumping means for regulating the pumping means in synchronism with heart pulsations including;

a pressure sensor detecting blood pressure at the ventricle during systole; and

servo control means connected in driving relationship with the pumping means and having programmed means defining a programmed systolic pressure and a servo control loop responsive to signals from the pressure sensor and the programmed means for driving the pumping means to maintain the programmed systolic pressure at the ventricle discharge during systole and to produce from the pumping means during intervals synchronized with heart pulsations a blood flow waveform which duplicates the ventricular blood flow waveform generated while maintaining the programmed systolic pressure.

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

the servo control means is a hydraulically powered servomechanism.

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

the blood pumping means comprises a displacement pump having inlet and discharge chambers which vary in volume by corresponding amounts in opposite senses.

4. A heart assist device as in claim 3 wherein the displacement pump also includes a flow-checking passageway ducting blood from the inlet chamber to the discharge chamber.

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

the inlet chamber of the displacement pump is connected with the heart ventricle; and

the pumping control means has the pressure sensor mounted in the inlet chamber of the displacement pump to detect systolic pressure.

6. A heart assist device as defined in claim 1 wherein the blood pumping means comprises a piston pump having coaxially aligned cylindrical inlet and discharge pumping chambers of the same diameter and a reciprocating piston in one chamber fixedly connected with a reciprocating piston of the other chamber.

7. A heart assist device as in claim 6 wherein the piston pump further includes a passageway leading between the inlet and discharge chambers and a check valve in the passageway preventing flow from the discharge chamber into the inlet chamber.

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

the blood pumping means includes an inlet chamber connectible with the heart ventricle, a discharge chamber connectible with the vascular system and a cooperating reciprocating member which moves from a starting position in one direction to ingest blood from the ventricle into the inlet chamber and expel blood from the discharge chamber and moves in the opposite direction to transfer ingested blood from the inlet chamber to the discharge chamber; and

the servo control means of the pumping control means has means for reversing the direction of movement of the reciprocating member in synchronism with the respective systolic and diastolic cardiac periods.

9. A heart assist device as defined in claim 8 wherein:

the pumping control means comprises copulsation pumping control means providing a pressure mode during the systolic cardiac period causing the servo control means to respond to the systolic pressure signals detected by the sensor to stroke the reciprocating member in said one direction and maintain said programmed systolic pressure, and providing a positioning mode of operation during the diastolic cardiac period causing the servo control means to stroke the reciprocating member in said opposite direction to the starting position.

10. A heart assist device as defined in claim 9 wherein the copulsation pumping control means includes:

a switch connected with and controlled by the pressure sensor, timing and sampling means controlled by the switch and sensor for measuring the diastolic period and means connected to the servomechanism for returning the reciprocating member to the starting position after the systolic period and within a time period less than the preceding diastolic period measured.

11. A heart assist device as defined in claim 10 wherein the copulsation pumping means further includes means for returning the reciprocating member to the starting position within said time period at a minimal velocity.

12. A heart assist device 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 pumping 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.

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

the programmed means defines the programmed systolic pressure as a constant pressure level throughout the systolic period.

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

the programmed means defines the programmed systolic pressure as a variable pressure waveform during the systolic period.

15. A heart assist device as defined in claim 14 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.

16. A heart assist device for operation in synchronism with ventricular heart contractions comprising:

blood pumping means serially connectible between the heart and the vascular system of the body for producing a pulsatile blood flow; and

control means connected to the pumping means including a pressure sensor connected with a heart ventricle and detecting blood pressure pulsations produced by the contractions of the ventricle, and means responsive to the pressure sensor for driving the pumping means to maintain a programmed reference pressure at the heart ventricle during systolic contractions and to reproduce the blood flow waveform from the ventricular contractions obtained when the programmed pressure reference is maintained.

17. A heart assist device as defined in claim 16 wherein:

the blood pumping means is a piston pumping having an inlet connectible with a heart ventricle; and

the pressure sensor is mounted in the pump adjacent the inlet to sense ventricular discharge pressure.

18. A heart assist device comprising in combination:

a pacemaker connected to the natural heart for electrically stimulating regular heart contractions;

a cyclically driven blood pump connectible to the vascular system of the body and producing pulsatile flow when driven; and

blood flow waveform generating means connected with both the pacemaker and the blood pump for driving the pump and pacemaker in synchronized relationship to produce pulsatile flow from the pump in synchronism with the heart stimulated by the pacemaker.

19. A heart assist device as in claim 18 wherein the blood flow waveform generating means is connected to control the cyclically driven blood pump and to trigger the pacemaker.

20. A heart assist device as in claim 18 wherein:

the blood pump is connectible with the discharge of a heart ventricle and the vascular system; and

pump control means responsive to the waveform generating are provided for cyclically driving the pump in copulsation with the contractions of the ventricle connected with the pump.