David A. Nathan

An Implantable, Synchronous Pacemaker for the Long-Term Correction of Complete Heart Block

An implantable, synchronous cardiac pacemaker for long-term correction of complete heart block has been developed. It has been successfully used in dogs for periods up to eight months. The performance of the pacemaker during normal sinus rhythm and atrial arrhythmias is illustrated with electrocardiograms. After implantation of the pacemaker, the dogs have returned to completely normal activity and have tolerated all physical exercises well. [see figure in the PDF file]

Preexcitation and Tachycardias in Wolff-Parkinson-White Syndrome, Type B: A Case Report

Electrophysiologic events in a 52-year-old man with Wolff-Parkinson-White (W-P-W) syndrome, type B, recurrent supraventricular tachycardias, and coronary artery disease were studied during cardiac catheterization and at open-heart surgery.During cardiac catheterization reciprocal tachycardias were repeatedly initiated by premature atrial beats and terminated by rapid right atrial pacing. Our results confirm that the tachycardia usually seen in the W-P-W syndrome is reciprocal tachycardias with orthograde conduction to the ventricles through the normal atrioventricular conduction system and retrograde conduction to the atria via the Kent bundle.The epicardial surface of the ventricles was “mapped’ at surgery. The earliest site of excitation was the posterior base of the left ventricle near the crux of the heart. Kent bundle conduction was temporarily ablated with lidocaine (Xylocaine) hydrochloride.This is the first case of W-P-W syndrome, type B, in which the anomalous A-V bundle entered the left ventricle. Our results indicate that the analysis of the electrocardiogram in localizing an abnormal A-V connection cannot be relied upon completely.

Rhythm anomalies in contemporary demand pacing

Abstract A change in pacemaker rate, a slightly erratic rate, and even the apparent failure to detect a spontaneous beat are not necessarily indications of pacemaker unit failure. Each rhythm must be examined in the context of accurate knowledge of the particular pacemaker, its parameters and perhaps its history.

Treatment of supraventricular tachycardias by right atrial alternating current stimulation

Abstract In 6 patients with Supraventricular tachycardias, induction of atrial fibrillation by alternating current stimulation of the right atrium was found to be an effective and safe method for terminating these arrhythmias or slowing the ventricular rate. The latter, after induction of atrial fibrillation, provided a good clinical guide for judging the need for further administration of digitalis

Percutaneous access to implanted electrodes

Abstract Obtaining direct electrical measurements from an implanted electronic prosthesis requires surgical intervention, and therefore has been impractical. A method is needed for easily measuring threshold currents and voltages during cardiac pacing, pacer output values for diagnosis of pacer failure and cardiac potentials for diagnosis of arrhythmias and detection of early rejection of the transplanted heart. Access to implanted electrodes for feed-in of external pulses is also needed. We have developed a system that allows direct percutaneous access to the implanted structure. It is compatible with virtually any electrode or pacer configuration and provides reliable, repeatable measurements. It involves a subcutaneous metal plaque covered with self-sealing silicone rubber, and a special percutaneous needle. The plaque may be connected to the implanted electrode or the pacer electrode terminal, or incorporated within the electrode connector assembly or the pulse generator. The needle, made of hardened alloy, is covered entirely with Teflon except for the extreme tip, and thus is insulated from the tissues. Several hundred measurements from 16 dogs and 7 human beings were taken, with no iatrogenic infections. Reliability was established by comparing percutaneous values with those obtained directly from the electrode connector. When properly done, percutaneous values were accurate within 10 percent. Reproducibility was established by repeatedly puncturing the skin and obtaining the same measure. On several trials, this was done by an unpracticed operator, indicating that success is not dependent on operator skill. In 36 repeated measurements, the mean deviation was 6.9 percent or less.

Intrapericardial pacemaking (a preliminary report).

Summary Intrapericardial pacing is a new and simple echnique of electrode placement for the long term correction of complete heart block. It requires the application of a specially designed electrode to the diaphragmatic surface of the parietal pericardium in contact with the inferior surface of the heart. A study in dogs established the feasibility of this type pacing for synchronous, standby and fixed rate modes of electrical stimulation. The first implant was performed on August 10, 1967. Thirteen patients were treated. Pacing was asynchronous in 10, synchronous in two and in one, pacing was not attempted because of technical factors. Long term pacing was maintained in nine patients. Three of the nine required corticosteroid therapy to overcome interference by post-operative pericarditis. A pervenous or myocardial system was substituted for intrapericardial pacing which failed early after surgery in three patients with adhesive pericarditis or pericardial effusion. It is the authors opinion that this is a valuable alternate or primary method for pacing. Its advantages include: 1) a simple safe operative approach, 2) a stable electrode fixation, 3) avoidance of ventricular muscle trauma and 4) minimal electrode motion resulting in less possibility of electrode breakage.