GB1536270A - Electrical current-carrying members - Google Patents

Abstract

1536270 Cardiac pacer leads GREATER GLASGOW HEALTH BOARD 2 Dec 1975 [3 Dec 1974] 52334/74 Heading A5R [Also in Division H1] A current carrying member for a cardiac pacemaker comprises a flexible insulating tube 2 and at least two different electrically conductive media within the tube, the media having different fatigue properties and each being capable of carrying, on its own, sufficient current to promote a pacemaking function in the heart. One of the media is a conductive fluid, sol, gel or paste. As shown one conductor is a coiled filament 3 of platinum or a platinum/iridium alloy, a second conductor is a conductive paste 4 and a third conductor is metallic coating 5 e.g. of platinum formed on the inside of the insulating tube 2. A fourth conductor may comprise a similar coating 8 on the outer surface of an inner conductive tube 1. All the conductors are connected to the heat electrode at one end and to the generator at the other; thus if the main conductor 3 fractures the remaining conductors provide sufficient current to promote the pacemaking function in the heart. A stylet 7 may be inserted in the inner tube 1 to facilitate insertion through veins. For bipolar devices two of the above conductors can be provided in a single insulating sheath. The insulating tubes may be of silicone rubber and the conducting medium between the tubes may be a conductive fluid, a conductive sol or a conductive gel. This medium may be made radio-opaque so that leaks can be detected.