TACHYCARDIA SENSING CIRCUIT FOR PACEMAKER

摘要

Mr. Barouh P rkovits179 Woodcli RoadNewton Highlands, Massachusetts 02161andMr. Ray S. McDonald2241 Marion StreetSt. Paul, Minnesota 55113M&G-1958.1/USATACHYCARDIA TREATMENTAbstract of the DisclosureTreatment of re-entry tachycardias through the useof a pacemaker which includes sequentially timed oscillatorsfor delivering stimulating pulses to an atrium and ventricle,preferably on a demand basis, and a circuit for detecting atachycardia condition and switching to an asynchronous modeof operation. The detector does not respond to a singleextraneous or premature beat, but after a predeterminednumber of beats occurring above a predetermined normal beatrate the detector switches the pacemaker to an asynchronousmode. Relative variation in the phase of the asynchronouspacing and the tachycardia beats results within a short timein occurrence of a pulse in the critical time period to stopthe tachycardia., The use of sequential stimulation in bothchambers overcomes some of the problems in selecting theproper site for stimulation. Hysteresis is provided in theheartbeat rate detecting circuit for preventing prematurediscontinuance of the asynchronous mode due to masking ofpulses by the refractory period of the QRS-wave amplifyingcircuits.