External cardiac programmed stimulation for noninvasive termination of sustained supraventricular and ventricular tachycardia.

To examine the feasibility of using a noninvasive temporary pacemaker for termination of well-tolerated supraventricular (SVT) and ventricular tachycardia (VT), a standard external demand pacemaker was modified to allow stimulation with single or multiple extrastimuli and overdrive pacing. To evaluate the efficacy, safety and tolerance of external cardiac programmed stimulation, a standard arrhythmia termination protocol was used in 223 tachycardias in 22 patients. The technique of external cardiac programmed stimulation was used in 209 episodes of SVT in 13 patients.

Hemodynamic responses to noninvasive external cardiac pacing.

Although improvements in noninvasive external cardiac pacing have led to a technique with reliable electrical capture and reduced patient discomfort, hemodynamic responses to this pacing mode have not been described previously. Accordingly, this technique was applied to 16 patients with a clinical diagnosis of angina pectoris undergoing cardiac catheterization. Three patients had normal coronary arteries, whereas the remaining 13 had significant coronary artery disease.

Noninvasive external cardiac pacing for thallium-201 scintigraphy.

Improvements in noninvasive external cardiac pacing have led to a technique with reliable electrical capture and tolerable patient discomfort. To assess the use of this modality of pacing in combination with thallium scintigraphy as a noninvasive pacing stress test, we applied simultaneous noninvasive cardiac pacing, hemodynamic monitoring, and thallium-201 scintigraphy in 14 patients undergoing cardiac catheterization for chest pain syndromes. Two patients had normal coronary arteries, while the remaining 12 had significant coronary artery disease.

Noninvasive temporary cardiac stimulation.

A new noninvasive temporary cardiac pacemaker-monitor has been developed to stimulate effective ventricular contraction in ventricular asystole or symptomatic bradycardia. It is quickly and easily applied, safe, and well tolerated even in conscious patients. It produced electrical cardiac responses in 105 of 134 patients; almost all of the remaining 29 patients were severely hypoxic.

External noninvasive temporary cardiac pacing: clinical trials.

An external cardiac pacemaker-monitor has been developed that provides safe, effective noninvasive ventricular stimulation that is well tolerated in conscious patients and allows clear recognition of electrocardiographic response. The noninvasive temporary pacemaker (NTP) has now been applied in 134 patients in five hospitals. Stimulation was tolerated well in 73 of 82 conscious patients, and nine found it intolerable.

Emergency noninvasive external cardiac pacing.

Thirty-seven critical emergency department patients underwent attempts at external cardiac pacing over an 11-month period. Indications for pacing were asystole in 16, complete heart block (CHB) in 4, sinus bradycardia in 2, nodal bradycardia in 1, atrial fibrillation with bradycardia in 2, electromechanical dissociation in 1, idioventricular rhythm (IVR) in 10, and torsades de pointes in 1. Eight patients were successfully paced with improvement in their condition.

Value of a noninvasively induced ventricular extrasystole during echocardiographic and phonocardiographic assessment of patients with idiopathic hypertrophic subaortic stenosis.

Fifteen patients with idiopathic hypertrophic subaortic stenosis had a ventricular extrasystole induced with a new external mechanical cardiac stimulator during noninvasive evaluation of left ventricular outflow tract obstruction. Ten patients were monitored with simultaneous echocardiogram, phonocardiogram and indirect carotid pulse tracing; five were monitored with the phonocardiogram and indirect carotid pulse tracing alone. Nine of the 15 patients showed obstruction in the beat after the ventricular extrasystole, as defined by appearance of the characteristic bifid carotid pulse contour and, where recorded, an increase in systolic anterior motion of the mitral valve on echocardiography.

A new, noninvasive technique for inducing post-extrasystolic potentiation during echocardiography.

Left ventricular function was evaluated in 34 patients with the echocardiogram, and an external mechanical cardiac stimulator was used to induce a ventricular premature contraction (VPC) noninvasively. Extent of post-extrasystolic potentiation (PESP) was determined by comparing systolic dimensional shortening and ejection fraction of the sinus beat preceding the VPC to that of the potentiated beat which followed it. Using this technique, a VPC could be introduced into the cardiac cycle of 30 of the 34 patients, six of whom were free of obvious cardiac disease and 24 of whom had valvular, coronary or myopathic heart disease.