The implantable defibrillator: an electronic bridge to cardiac transplantation.

Background: Sudden cardiac death (SCD) is common among patients awaiting heart transplantation. Medical management of SCD may fail due to lack of efficacy or adverse side effects. The implantable cardioverter-defibrillator (ICD) may extend patient survival until a donor heart is available.

Methods of implantable cardioverter-defibrillator-pacemaker insertion to avoid interactions.

Experience with combined transvenous pacemaker and implantable cardioverter-defibrillator insertion in 21 patients is described. Special techniques are needed to avoid potentially lethal pacemaker-implantable cardioverter-defibrillator interaction. Separation between leads for the two devices should be maximized.

Effect of electrophysiological testing on ejection fraction during cardioverter/defibrillator implantation.

To evaluate the effect of repeated induction of ventricular tachycardia or ventricular fibrillation, or both, in patients with poor left ventricular function, we performed intraoperative two-dimensional echocardiography in 6 patients undergoing implantation of the automatic implantable cardioverter/defibrillator. Changes in left ventricular ejection fraction in sinus rhythm were assessed before the first inducible ventricular arrhythmia and after a mean of 6 +/- 1.9 (SD) episodes of ventricular tachycardia or ventricular fibrillation.

Electrophysiologic testing in patients with recurrent syncope: are results predicted by prior ambulatory monitoring?

Syncope is a common medical problem which can result from many etiologies, including cardiac dysrhythmias. Because ambulatory monitoring usually fails to capture a syncopal episode, electrophysiologic testing has been used to elucidate dysrhythmic mechanisms in patients with recurrent syncope. To assess whether findings on ambulatory monitoring not obtained during syncope can be used to indicate the results which are found on electrophysiologic testing in patients with recurrent syncope, we reviewed the ambulatory monitoring records of 59 such patients referred for electrophysiologic testing.

Sinus node echoes and concealed concealed conduction: additional sinus node phenomena confirmed in man by direct sinus node electrography.

Direct sinus node electrography has been previously used to assess several aspects of sinus node physiology: sinus node pauses, overdrive suppression, sinoatrial entrance block. This report presents data in which sinus node electrograms confirm two additional physiologic phenomena in man: concealed conduction in the sinoatrial junction and sinus node reentry. These findings verify the presence of previously suspected phenomena by careful deductive analysis of electrocardiographic and electrographic tracings.

Indirectly estimated sinoatrial conduction time by the atrial premature stimulus technique: patterns of error and the degree of associated inaccuracy as assessed by direct sinus node electrography.

The atrial premature stimulus method for estimating sinoatrial conduction time (SACT) is commonly used. When the stimulated atrial premature depolarization (APD) does not appear to affect sinus node automaticity or conduction, the indirectly estimated SACT (SACT1) is quite accurate. That is, SACT1 correlates quite highly with SACT measured directly (SACTD) on sinus node electrograms (SNE).

Sinus node recovery times following the spontaneous termination of supraventricular tachycardia and following atrial overdrive pacing: a comparison.

We compared the pauses that followed the spontaneous termination of supraventricular tachyarrhythmias with the pauses that followed the cessation of atrial overdrive pacing in 21 patients. In 10 patients with abnormal sinus node function and in 11 patients with normal sinus node function we recorded the spontaneous termination of supraventricular tachyarrhythmia in the clinical electrophysiology laboratory; a strong correlation (r = 0.94) was found between the maximal spontaneous sinus node recovery time and the maximal paced sinus node recovery time.

Sinus node recovery time related to paced cycle length in normals and patients with sinoatrial dysfunction.

Depressed conduction in the sinoatrial junction, common in the sick sinus syndrome (SSS), should decrease the maximum pacing rate at which 1:1 capture of the SA node occurs. This may result in shorter than expected sinus recovery times (SRT) and maximal prolongation of SRT at relatively slow pacing rates. To test this hypothesis we evaluated the range of pacing rates necessary to demonstrate maximal SRT in 34 patients with and 20 patients without sinus node dysfunction.

A model of chronic ischemic arrhythmias: the relation between electrically inducible ventricular tachycardia, ventricular fibrillation threshold and myocardial infarct size.

To study the relation between inducible ventricular tachycardia and ventricular vulnerability, myocardial infarction was created in 22 closed chest mongrel dogs by inflating a balloon catheter in the left anterior descending coronary artery for 2 hours. The presence of inducible ventricular tachycardia was determined by programmed electrical stimulation of the right ventricle in each dog before and 4 days after infarction, using a transvenous electrode catheter and a "clinical" stimulation protocol. In each dog the repetitive ventricular response threshold and the ventricular fibrillation threshold were measured before and 4 days after infarction.

Response to programmed ventricular stimulation: sensitivity, specificity and relation to heart disease.

This prospective study of 100 patients evaluated the sensitivity and specificity of the repetitive ventricular response and ventricular tachycardia induced by programmed electrical stimulation for identifying patients with spontaneous ventricular tachyarrhythmias. The influence of underlying heart disease on such sensitivity and specificity was also evaluated. The repetitive ventricular response was sensitive (92 percent) for detecting patients with prior spontaneous ventricular tachyarrhythmias, but lacked specificity (57 percent); the rate of false positive responses was 43 percent.

Electrophysiologic effects of procainamide on sinus function in patients with and without sinus node disease.

To compare the effects of procainamide on sinus node (SN) function in the presence (seven patients) and absence (nine patients) of SN dysfunction, sinus cycle length (SCL), maximal corrected sinus recovery time (maximal CRST), paced cycle length yielding peak SN suppression (PCLp), and indirect sinoatrial conduction time (SACT) were determined before and after intravenous administration of 10 to 15 mg/kg procainamide in each patient. Plasma procainamide concentration was in the therapeutic range in all patients. The mean SCL did not change significantly in either group (-24 +/- 58 and -73 +/- 171 msec for patients with normal and abnormal SN function, respectively).

Clinical and electrophysiologic characteristics of sinoatrial entrance block evaluated by direct sinus node electrography: prevalence, relation to antegrade sinoatrial conduction time, and relevance to sinus node disease.

When AV conduction is normal, the absence of VA conduction is not abnormal. Analogous information about retrograde sinoatrial conduction is not available. Although the premature atrial stimulas (PAS) technique can demonstrate the presence of sinoatrial entrance block (SAEB), both its prevalence and its relationship to antegrade SA conduction are unknown.

Unexplained in-hospital fever following cardiac surgery. Natural history, relationship to postpericardiotomy syndrome, and a prospective study of therapy with indomethacin versus placebo.

In Part I of this study, the in-hospital course of 219 patients who had undergone a cardiac operation is analyzed. Fever (greater than or equal to 37.8 degrees C, rectal) was present after postoperative day 6 in 159 patients (73%) and was of unexplained cause in 118.