Ethics considerations for medical device R&D.

Medical devices have emerged as an important clinical option to treat certain serious diseases for which there are no equivalently effective surgical or pharmaceutical alternatives. Although all clinical activities impose high ethical standards of comportment to protect patients, medical device R&D and product application have a number of relatively unique aspects that distinguish them from other technologies such as pharmaceuticals. These include the following: R&D project selection; regulatory requirements, and their intended and unintended effects; when is a new product design sufficiently safe and effective for routine use in patients; and, physician-industry relationships in the innovation process in the context of real or perceived conflict of interest (COI).

Incidence of coronary artery by-pass graft following percutaneous transluminal coronary angioplasty.

Two hundred fifty eight patients had percutaneous transluminal coronary angioplasty. Of those, 48 cases underwent surgical revascularization for unsuccessful angioplasty. Sex was not a risk factor.

Hemodynamic and myocardial performance characteristics after verapamil use in congestive heart failure.

Because of its intrinsic negative inotropic effect, the administration of the recently introduced calcium antagonist, verapamil, is thought to be contraindicated in presence of congestive heart failure (CHF). Yet, as CHF is frequently associated with arrhythmias and angina pectoris, and verapamil possesses potent antiarrhythmic and antianginal properties that could be of great benefit to selected patients with CHF, this study was undertaken to determine whether verapamil can be given to such subjects safely. For this purpose, 14 patients with CHF were studied in the control (preverapamil) state with a combined hemodynamic-cineangiographic approach; the same interventions were repeated during intravenous verapamil administration (0.

Verapamil versus placebo in relieving stable angina pectoris.

Verapamil and placebo were compared in patients with stable, effort-induced angina. Single-blind dose titration (240, 360 and 480 mg/day) preceded a double-blind crossover. Among the 18 patients who completed graded exercise stress tests with reproducible pretreatment effort-limiting angina, exercise duration increased from 348 +/- 127 seconds (SD) before treatment to 494 +/- 182 seconds after verapamil (p less than 0.

Physiological cardiac pacing.

With the availability of reliable transvenous atrial leads and advances in electronic and battery technology, pacing for the restoration of the atrioventricular sequence has become practicable. This paper presents (1) a historical review of physiological cardiac pacing, and (2) a functional description of pacemakers currently available or in clinical validation. The indications and limitations of use for each is discussed on the basis of clinical experience in 176 patients.

Implantable pacemakers for management of tachyarrhythmias.

Attempts have been made to control tachyarrhythmias with implantable pacemakers since the late 1960's. The basic approaches considered were: a) maintenance of a basic rate following surgical division of the conducting system, b) pacing to prevent onset of tachyarrhythmias, and c) pacing to terminate episodes of tachyarrhythmias. The earliest approaches required conscious patient interaction in effecting therapy.

Electrophysiological and haemodynamic basis for application of new pacemaker technology in sick sinus syndrome and atrioventricular block.

A fundamental description of pacemaker systems which are commercially available or in clinical validation is given as a background for their application in a series of 62 consecutive patients presenting over a period of 1 year for permanent cardiac pacing. The patients (23 (37%) sick sinus syndrome, 38 (61%) atrioventricular block, and 1 ventricular tachycardia) were studied electrophysiologically and haemodynamically to allow the appropriate application of a pacemaker system. In sick sinus syndrome, 8 patients had permanent atrial pacing, 14 ventricular pacing, and 1 atrioventricular sequential pacing; in atrioventricular block, 8 patients had atrial synchronous ventricular inhibited pacing and the remaining 30 had ventricular pacing.

Clinical experience with a new transvenous atrial lead.

Although systems using atrial pacemakers offer potential clinical advantages for many patients now receiving ventricular devices, atrial systems have been used in less than 1% of the implantations of permanent pacemakers. The unavailability of clinically successful, easily positioned atrial leads is regarded as the most significant factor in the underutilization of atrial pacing systems. A permanent transvenous atrial lead has been developed and has performed well in 16 months of evaluation in 28 patients.

Permanent pervenous atrial sensing and pacing with a new J-shaped lead.

We have developed a new J-shaped lead for atrial pacing. The lead has silicone rubber tines which become entangled in the trabeculae and thereby anchor the lead firmly in the left atrial appendage. Later, scar tissue forms around the tines, rather than around the electrode, so that there is no problem with either lead displacement or loss of sensing.

Patient-initiated rapid atrial pacing to manage supraventricular tachycardia.

Patient-controlled rapid atrial pacing was used to manage 12 cases of recurrent supraventricular tachycardia refractory to drug therapy. The pacing system consists of an implanted receiver-lead system and an external patient-activated transmitter. In each case, brief periods (5 to 20 seconds) of rapid atrial pacing were effective in terminating the supraventricular tachycardia and resulted in a return to normal sinus rhythm.

The triple pulse generator: Clinical evaluation of a new multipurpose external pulse generator.

This report describes our experience with a new, versatile battery operated, multi-purpose pulse generator especially designed for the electrophysiological investigation and treatment of cardiac arrhythmias in man. The unit was constructed according to our specifications and has been clinically in 75 patients over a period of 18 months. We have found the triple pulse pacemaker safe, reliable and functioning precisely according to specifications both clinically and when repeatedly checked with a storage oscilloscope.