Long-term atrial pacing for sinus node disease with output-terminal programmagle pacemakers.

Long-term transvenous atrial pacing for symptomatic sinus node disease, in the absence of atrioventricular conduction disease, confers the advantages of increased cardiac performance and probable freedom from systemic thromboembolism. Conventional ventricular pacing has been preferred, however, because of the complications of atrial pacing, mainly those of electrical and mechanical instability of currently available atrial electrodes. These complications have been circumvented with a new pacemaker, programmable for output terminal. This has allowed the institution of atrial pacing in seven patients, with its attendant advantages and the ability to reprogram noninvasively to ventricular pacing should atrial pacing fail. Such reprogramming has been accomplished without difficulty in one patient who developed second-degree atrioventricular block and one with electrode microdisplacement.