ATRIAL AND VENTRICULAR DEMAND PACER HAVING WIDE-RANGE ATRIAL ESCAPE INTERVAL

摘要

1416563 Demand pacemakers AMERICAN OPTICAL CORP 9 March 1973 [9 March 1972] 11620/73 Heading A5R [Also in Division H3] An atrial and ventricular demand heart pacemaker has ventricular pulse generating means T9, 65 for generating a ventricular stimulating pulse at the expiration of a ventricular timing interval, synchronising means T6, T7, T8 responsive to synchronise the ventricular pulse generator to the beating action of the patients' heart, timing means T10, 58, 62 responsive to the operation of the synchronising means for controlling an atrial timing interval, means 62 for adjusting the duration of the atrial timing interval, and means T11, T12 responsive to the expiration of the atrial timing interval for generating at most one atrial stimulating pulse for each ventricular beating action of the patients' heart. The synchronising means and the ventricular stimulating pulse generator are identical to the circuits disclosed in Applications Nos. 88/73 and 1024/75 but the atrial pulse generator comprises an atrial timing circuit controlling conduction of transistor T14 to discharge a capacitor 82 through the primary of transformer 80 to produce an atrial stimulating pulse at electrodes E3, E4. The atrial timing interval is determined by the charging of a capacitor 58 through a resistor 62, adjustable to alter this interval, and is prematurely terminated whenever a spontaneous ventricular beat is detected, or a ventricular stimulating pulse is produced, by discharge of capacitor 58 through transistor T10, the voltage timing circuit is not reset by transistor T10, the voltage on capacitor 58 reaches a level to fire transistors T11, T12 to discharge itself therethrough giving rise to conduction of transistor T14 and production of an atrial stimulating pulse. A variable resistor 95 sets the atrial pulse width. The circuit comprising transistors T15, T16, resistors 92, 94, 95 96, 97 and capacitor 93 act to prevent transistors T11, T12 turning off following discharge of capacitor 58 therethrough until transistor T10 conducts again to discharge capacitor 58 completely. Thus production of multiple atrial stimulations between successive ventricular beats, either or both of which may be spontaneous or stimulated, is prevented even though the atrial timing interval may be adjusted by resistor 62 to be less than half the ventricular timing interval, which is adjustable by resistor 35.