# US 5,069,680 A · Muscle stimulator with variable duty cycle > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,069,680 A - Document ID: US5069680A - Status: Granted - Kind: A - Application number: 07/446,794 - Filed: 1989-12-06 - Granted: 1991-12-03 - Earliest claimed: 1989-12-06 - Assignees: Medtronic, Inc. - Inventors: Pierre-Andre Grandjean - Web page: https://patentgrep.com/patent/US5069680A ## CPC - A61N 1/36042: {of grafted tissue, e.g. skeletal muscle} - A61M 60/148: in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices - A61M 60/161: mechanically acting upon the outside of the patient's blood vessel structure, e.g. compressive structures placed around a vessel - A61M 60/191: mechanically acting upon the outside of the patient's native heart, e.g. compressive structures placed around the heart - A61M 60/289: Devices for mechanical circulatory actuation assisting the residual heart function by means mechanically acting upon the patient's native heart or blood vessel structure, e.g. direct cardiac compression [DCC] devices - A61M 60/515: Regulation using real-time patient data - A61M 60/531: using blood pressure data, e.g. from blood pressure sensors - A61M 60/882: Devices powered by the patient, e.g. skeletal muscle powered devices - A61M 60/274: the inlet and outlet being the same, e.g. para-aortic counter-pulsation blood pumps - A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B) - A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)} ## Abstract Apparatus and method of controlling a muscle stimulator by varying the duty cycle. The muscle stimulator is particularly adapted to a skeletal muscle powered cardiac assist system. An activity or other sensor is used to determine the requirement for cardiac output. A second electrical sensor is used to determine the cardiac rate. The outputs of these two sensors are employed to select a duty cycle for muscle stimulation of the skeletal muscle. The duty cycle is lowered for reasons of efficiency and safety during periods of very high or very low cardiac rate or body activity. The number of stimulation pulses within a burst is similarly increased when cardiac demand is high to ensure maximum contractile force of the skeletal muscle during each stimulation burst. ## Claims ### Claim 1 Apparatus comprising: a. a surgically prepared skeletal muscle adapted to be mechanically coupled to a natural human heart having ventricles which contract at a ventricular rate such that contraction of said surgically prepared skeletal muscle assists said natural human heart; b. means responsively coupled to said natural human heart and said surgically prepared skeletal muscle for stimulating said skeletal muscle in synchrony with contraction of said ventricles of said natural human heart, said stimulation having parameters including pulse amplitude, duty cycle, pulses per burst, pulse width, and pulse interval; and c. means responsively coupled to said stimulating means and adapted to be connected to a human body for sensing anticipated cardiac demand. ### Claim 2 (depends on 1) Apparatus according to claim 1 further comprising: means responsively coupled to said stimulating means and said sensing means for varying at least one of said parameters of stimulation of said stimulating means. ### Claim 3 (depends on 2) Apparatus according to claim 2 wherein said at least one of said parameters of stimulation includes pulse amplitude. ### Claim 4 (depends on 2) Apparatus according to claim 2 wherein said at least one of said parameters of stimulation includes duty cycle. ### Claim 5 (depends on 2) Apparatus according to claim 2 wherein said at least one of said parameters of stimulation includes number of pulses per burst. ### Claim 6 (depends on 2) Apparatus according to claim 2 wherein said at least one of said parameters of stimulation includes pulse width. ### Claim 7 (depends on 2) Apparatus according to claim 2 wherein said at least one of said parameters of stimulation includes pulse interval. ### Claim 8 A method of assisting cardiac activity of a natural human heart having ventricles which contract at a ventricular rate comprising: a. surgically preparing a skeletal muscle; b. positioning said skeletal muscle such that contraction of said skeletal muscle synchronously with contraction of said ventricles assists said cardiac activity; c. determining anticipated cardiac demand; and d. stimulating said skeletal muscle to contract synchronously with contraction of said centricles in accordance with said anticipated cardiac demand. ### Claim 9 (depends on 8) A method according to claim 8 wherein said determining anticipated cardiac demand includes sensing body activity.