EP0402872A1 — In-series ventricular assist system

Claim 1

Independent Claim 116 words

An in-series left ventricular assist system for assisting the circulation of blood in a patient, comprising: a pumping bladder for disposal in the thoracic aorta of the patient; means for detecting selected physiologic events relating to each heart beat; gas handling means for inflating and deflating said pumping bladder in accordance with said detected physiologic events and a predetermined set of assist system parameters; and control means for evaluating the effects of inflation and deflation of said pumping bladder and the corresponding assistance on the patient for each heart beat, and for altering said assist system parameters for each subsequent heart beat in accordance with the effects of assistance of said pumping bladder on the patient.

Claim 2

Dependent Claim 116 words

An in-series left ventricular assist system for assisting the circulation of blood in a patient, comprising: a pumping bladder for disposal in the thoracic aorta of the patient; means for detecting selected physiologic events relating to each heart beat; gas handling means for inflating and deflating said pumping bladder in accordance with said detected physiologic events and a predetermined set of assist system parameters; and control means for evaluating the effects of inflation and deflation of said pumping bladder and the corresponding assistance on the patient for each heart beat, and for altering said assist system parameters for each subsequent heart beat in accordance with the effects of assistance of said pumping bladder on the patient.

Claim 3

Dependent Claim 30 words

The in-series left ventricular assist system of claim 1, wherein said detecting means includes means for sensing said selected physiologic events, said sensing means being disposed proximate said pumping bladder.

Claim 4

Dependent Claim 40 words

The in-series left ventricular assist system of claim 2, wherein said sensing means includes means for sensing the electrocardiogram and the aortic blood pressure of the patient,and for generating signals in accordance with said measured electrocardiogram and aortic blood pressure.

Claim 5

Dependent Claim 33 words

The in-series left ventricular assist system of claim 1, wherein said gas handling means includes means for selectively adjusting for each heart beat, the amount of gas used to inflate said pumping bladder.

Claim 6

Dependent Claim 65 words

The in-series left ventricular assist system of claim 1, wherein said gas handling means comprises: a shuttle gas circuit having a shuttle gas therein; means for pressurizing and depressurizing said shuttle gas in said circuit; means for adding and exhausting shuttle gas to and from said shuttle gas circuit; and valve means for regulating the flow of shuttle gas to and from said pumping bladder.

Claim 7

Dependent Claim 69 words

The in-series left ventricular assist system of claim 5, including: an isolation chamber connected on one side thereof to said shuttle gas circuit; an air circuit connected to the opposite side of said isolation chamber; and wherein said pressurizing means includes a source of compressed air and a regulated vacuum, and control valve means for connecting said source of compressed air and said regulated vacuum to said air circuit.

Claim 8

Dependent Claim 41 words

The in-series left ventricular assist system of claim 6, wherein said isolation chamber includes a diaphragm dividing said isolation chamber into an air side and a shuttle gas side, and means for detecting displacement of said diaphragm in said isolation chamber.

Claim 9

Dependent Claim 90 words

The in-series left ventricular assist system of claim 5, wherein said control means includes: shuttle gas volume control means for maintaining a selected volume of shuttle gas in said shuttle gas circuit, said shuttle gas volume control means including means for monitoring a difference beween pumping bladder pressure and the patient's aortic pressure when said pumping bladder is inflated, said shuttle gas volume control means being operable to control said means for adding and exhausting shuttle gas in accordance with said monitored difference between pumping bladder pressure and aortic pressure.

Claim 10

Dependent Claim 78 words

The in-series left ventricular assist system of claim 5, wherein said valve means is operable to an open position for a predetermined period of time to inflate said pumping bladder, and said control means is operable to selectively adjust said predetermined period of time of inflation of each heart beat such that the amount of shuttle gas admitted into said pumping bladder is sufficient for complete inflation while maintaining a transmembrane pressure of less than 50 mm Hg.

Claim 11

Dependent Claim 81 words

The in-series left ventricular assist system of claim 5, wherein said valve means is operable to an open position for a predetermined period of time to deflate said pumping bladder, and said control means is operable to selectively adjust said predetermined period of time of deflation for each heart beat such that the amount of shuttle gas removed from said pumping bladder is sufficient to completely empty said balloon while limiting residual intraballoon pressure to no less than 0 mm Hg.

Claim 12

Dependent Claim 142 words

The in-series left ventricular assist system of claim 1, wherein said detecting means includes means for detecting each occurrence of a QRS wave and for measuring the time interval between successive QRS waves, and pressure sensing means for determining, for each heart beat, a) a time interval between detection of the QRS wave and opening of the aortic valve; b) aortic pressure at opening of the aortic valve; c) a time interval between detection of the QRS wave and closing of the aortic valve; d) aortic pressure at closing of the aortic valve; e) a time interval between detection of the QRS wave and an initial effect on aortic pressure caused by inflation of said pumping bladder; and f) respective time intervals between detection of the QRS wave and the end of inflation and the end of deflation of said pumping bladder.

Claim 13

Dependent Claim 135 words

The in-series left ventricular assist system of claim 11, including means for storing said detected physiologic events and associated assist system parameters for a predetermined number of preceding heart beats prior to each subsequent heart beat, and means for comparing said detected physiologic events of each heart beat with said stored physiologic events to select at least one of said predetermined number of preceding heart beats as a reference heart beat, and wherein said control means includes an inflation means for initiating inflation of said pumping bladder at a predetermined time delay after detection of the QRS wave for each heart beat, said predetermined time delay being selected by said inflation means in accordance with said time interval between detection of the QRS wave and initial effect on aortic pressure for said reference heart beat.

Claim 14

Dependent Claim 136 words

The in-series left ventricular assist system of claim 12, wherein said inflation means includes means for recomputing said time delay from the detected QRS to the inflation of said pumping bladder for each heart beat according to the following rules: a) if on said reference heart beat the detected beginning of balloon inflation occurred before the detection of the closing of the aortic valve, then increase said time delay for the present heart beat by a predetermined amount in excess of said time delay on said reference heart beat; b) if on said reference heart beat the detected beginning of balloon inflation occurred after the detection of the closing of the aortic valve, then decrease said time delay for the present heart beat by a predetermined amount from said time delay on said reference heart beat.

Claim 15

Dependent Claim 94 words

The in-series left ventricular assist system of claim 11, wherein said control means includes means for initiating deflation of said pumping bladder a predetermined time delay after detection of the QRS wave, said predetermined time for initiating deflation being selected by said deflation means in accordance with: a) the temporal relationship between said detected opening of the aortic valve, end of pumping bladder deflation, and detected closing of the aortic valve; and b) the aortic pressure at the opening of the aortic valve and the aortic pressure at the closing of the aortic valve.

Claim 16

Dependent Claim 187 words

An in-series left ventricular assist system for assisting the circulation of blood in a patient, comprising: a pumping bladder for disposal in the thoracic aorta of the patient; means for detecting selected physiologic events relating to each heart beat; gas handling means for inflating and deflating said pumping bladder in accordance with said detected physiologic parameters and a predetermined set of assist system parameters; means for storing said detected physiologic events and associated assist system parameters for a predetermined number of preceding heart beats prior to each subsequent heart beat; means for comparing the detected physiologic events of each heart beat with said stored physiologic events to select at least one of said predetermined number of preceding heart beats as a reference heart beat; and control means for evaluating the effects of inflation and deflation of said pumping bladder and the corresponding assistance on the patient for said selected preceding reference heart beat, and for altering said assist system parameters for each subsequent heart beat in accordance with said evaluated effects of assistance of said pumping bladder on the patient for said selected preceding reference heart beat.

Claim 17

Dependent Claim 187 words

An in-series left ventricular assist system for assisting the circulation of blood in a patient, comprising: a pumping bladder for disposal in the thoracic aorta of the patient; means for detecting selected physiologic events relating to each heart beat; gas handling means for inflating and deflating said pumping bladder in accordance with said detected physiologic parameters and a predetermined set of assist system parameters; means for storing said detected physiologic events and associated assist system parameters for a predetermined number of preceding heart beats prior to each subsequent heart beat; means for comparing the detected physiologic events of each heart beat with said stored physiologic events to select at least one of said predetermined number of preceding heart beats as a reference heart beat; and control means for evaluating the effects of inflation and deflation of said pumping bladder and the corresponding assistance on the patient for said selected preceding reference heart beat, and for altering said assist system parameters for each subsequent heart beat in accordance with said evaluated effects of assistance of said pumping bladder on the patient for said selected preceding reference heart beat.

Claim 18

Dependent Claim 142 words

The in-series left ventricular assist system of claim 15, wherein said detecting means includes means for detecting each occurrence of a QRS wave and for measuring the time interval between successive QRS waves, and pressure sensing means for determining, for each heart beat: a) a time interval between detection of the QRS wave and opening of the aortic valve; b) aortic pressure at opening of the aortic valve; c) a time interval between detection of the QRS wave and closing of the aortic valve; d) aortic pressure at closing of the aortic valve; e) a time interval between detection of the QRS wave and an initial effect on aortic pressure caused by inflation of said pumping bladder; and f) respective time intervals between detection of the QRS wave and the end of inflation and the end of deflation of said pumping bladder.

Claim 19

Dependent Claim 74 words

The in-series left ventricular assist system of claim 16, wherein said control means includes an inflation means for initiating inflation of said pumping bladder at a predetermined time delay after detection of the QRS wave for each subsequent heart beat, said predetermined time delay being selected by said inflation means in accordance with said time interval between detection of the QRS wave and initial effect on aortic pressure for said selected preceding heart beat.

Claim 20

Dependent Claim 142 words

The in-series left ventricular assist system of claim 17, wherein said inflation means includes means for recomputing said time delay from the detected QRS wave to the initiation of inflation of said pumping bladder for each subsequent heart beat according to the following rules: a) if on said selected preceding heart beat the detected beginning of balloon inflation occurred before the detection of the closing of the aortic valve, then increase said time delay for the present heart beat by a predetermined amount in excess of said time delay on said reference heart beat; b) if on said selected preceding heart beat the detected beginning of balloon inflation occurred after the detection of the closing of the aortic valve, then decrease said time delay for the present heart beat by a predetermined amount from said time delay on said reference heart beat.

Claim 21

Dependent Claim 95 words

The in-series left ventricular assist system of claim 16, wherein said control means includes means for initiating deflation of said pumping bladder a predetermined time delay after detection of the QRS wave, said predetermined time delay for initiating deflation being selected by said deflation means in accordance with: a) the temporal relationship between said detected opening of the aortic valve, end of pumping bladder deflation, and detected closing of the aortic valve; and b) the aortic pressure at the opening of the aortic valve and the aortic pressure at the closing of the aortic valve.

Claim 22

Independent Claim 110 words

A method for controlling inflation and deflation timing of an in-series left ventricular assist system, comprising the steps of: detecting selected physiologic events relating to each heart beat; inflating and deflating said pumping bladder at selected times; storing, for a selected number of previous heart beats, the detected physiologic events relating to said previous heart beats and said selected times of inflation and deflation of said pumping bladder during said previous heart beats; and adjusting the selected times of inflation and deflation of said pumping bladder for each subsequent heart beat in accordance with the effects of pumping bladder inflation and deflation on the patient for said stored physiologic events.

Claim 23

Independent Claim 110 words

A method for controlling inflation and deflation timing of an in-series left ventricular assist system, comprising the steps of: detecting selected physiologic events relating to each heart beat; inflating and deflating said pumping bladder at selected times; storing, for a selected number of previous heart beats, the detected physiologic events relating to said previous heart beats and said selected times of inflation and deflation of said pumping bladder during said previous heart beats; and adjusting the selected times of inflation and deflation of said pumping bladder for each subsequent heart beat in accordance with the effects of pumping bladder inflation and deflation on the patient for said stored physiologic events.

Claim 24

Dependent Claim 96 words

The method of claim 20, wherein the step of adjusting the times of inflation and deflation of said pumping bladder includes the substeps of: comparing said detected physiologic events of each subsequent heart beat with said stored physiologic events of said previous heart beats; selecting at least one of said previous heart beats in accordance with said comparison of physiologic events; and adjusting the inflation and deflation timing of said pumping bladder for each subsequent heart beat in accordance with the effects of inflation and deflation of said pumping bladder on said selected previous heart beat.

Claim 25

Independent Claim 137 words

A method of controlling, for each heart beat of a patient, the volume of inflation of an in-series left ventricular assist device, the assist device including a drive unit and pump means for cyclically inflating and deflating a pumping bladder disposed in the thoracic aorta of the patient, comprising the steps of: detecting selected physiologic events relating to each heart beat; detecting selected pneumatic events relating to each pump cycle within the drive unit; pumping shuttle gas into said pumping bladder for a selected time interval; storing, for a selected number of preceding heart beats, the detected physiologic events, the detected pneumatic events, and the associated inflation time interval; and adjusting the inflation time intervals for each subsequent heart beat according to a comparison of the stored detected physiologic events with the associated stored detected pneumatic events.

Claim 26

Independent Claim 137 words

A method of controlling, for each heart beat of a patient, the volume of inflation of an in-series left ventricular assist device, the assist device including a drive unit and pump means for cyclically inflating and deflating a pumping bladder disposed in the thoracic aorta of the patient, comprising the steps of: detecting selected physiologic events relating to each heart beat; detecting selected pneumatic events relating to each pump cycle within the drive unit; pumping shuttle gas into said pumping bladder for a selected time interval; storing, for a selected number of preceding heart beats, the detected physiologic events, the detected pneumatic events, and the associated inflation time interval; and adjusting the inflation time intervals for each subsequent heart beat according to a comparison of the stored detected physiologic events with the associated stored detected pneumatic events.

Claim 27

Dependent Claim 67 words

The method of claim 22, wherein the adjusting step includes the substeps of: a) decrementing the inflation time interval where driveline pressure exceeds aortic pressure by more than a nominal 10 mm Hg, measured at the peak of diastole; b) incrementing the inflation time interval when driveline pressure does not exceed aortic pressure by more than a nominal 10 mm Hg, measured at the peak of diastolee.

Claim 28

Independent Claim 138 words

A method of controlling, for each heart beat of a patient, the volume of deflation of an in-series left ventricular assist device, the assist device including pump means and associated drive unit for cyclically inflating and deflating a pumping bladder disposed in the thoracic aorta of the patient, comprising the steps of: detecting selected physiologic events relating to each heart beat; detecting selected pneumatic events relating to each pump cycle within the drive unit; pumping shuttle gas out of said pumping bladder for a selected time interval; storing, for a selected number of preceding heart beats, the detected physiologic events, the detected pneumatic events, and the associated deflation time interval; and adjusting the deflation time intervals for each subsequent heart beat according to a comparison of the stored detected physiologic events with the associated stored detected pneumatic events.

Claim 29

Independent Claim 138 words

A method of controlling, for each heart beat of a patient, the volume of deflation of an in-series left ventricular assist device, the assist device including pump means and associated drive unit for cyclically inflating and deflating a pumping bladder disposed in the thoracic aorta of the patient, comprising the steps of: detecting selected physiologic events relating to each heart beat; detecting selected pneumatic events relating to each pump cycle within the drive unit; pumping shuttle gas out of said pumping bladder for a selected time interval; storing, for a selected number of preceding heart beats, the detected physiologic events, the detected pneumatic events, and the associated deflation time interval; and adjusting the deflation time intervals for each subsequent heart beat according to a comparison of the stored detected physiologic events with the associated stored detected pneumatic events.

Claim 30

Dependent Claim 65 words

The method of claim 24, wherein the adjusting step includes the substeps of: incrementing the deflation time interval where driveline pressure exceeds a nominal 10 mm Hg, measured just prior to the issuance of an inflation command; and decrementing the deflation time interval where the driveline pressure does not exceed a nominal 10 mm Hg, measured just prior to the issuance of an inflation command.

In-series ventricular assist system

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