Biomedical subjects

C A Kinder

Publications and source records attributed to C A Kinder.

3 recordsLinked to original sources

PubMed1997

Adenosine-sensitive bundle branch reentry.

INTRODUCTION: Bundle branch reentry is an uncommon mechanism for ventricular tachycardia. More infrequently, both fascicles of the left bundle may provide the substrate for such macroreentrant bundle branch circuits, so-called interfascicular reentry. The effect of adenosine on bundle branch reentrant mechanisms of tachycardia is unknown. METHODS AND RESULTS: A 59-year-old man with no apparent structural heart disease and history of frequent symptomatic wide complex tachycardias was referred to our center for further electrophysiologic evaluation. During electrophysiologic study, a similar tachycardia was reproducibly initiated only during isoproterenol infusion, which had the characteristics of bundle branch reentry, possibly using a left interfascicular mechanism. Intravenous adenosine reproducibly terminated the tachycardia. Application of radiofrequency energy to the breakout site from the left posterior fascicle prevented subsequent tachycardia induction and rendered the patient free of spontaneous tachycardia during long-term follow-up. CONCLUSIONS: Patients with ventricular tachycardia involving a bundle branch reentrant circuit may be sensitive to adenosine. These results suggest that adenosine may not only inhibit catecholamine-mediated triggered activity but also some catecholamine-mediated reentrant ventricular arrhythmias.

Adenosine↗

PubMed1995

Catheter ablation of the mitral isthmus for ventricular tachycardia associated with inferior infarction.

BACKGROUND: Intraoperative mapping studies suggest that an isthmus of myocardium between the mitral valve annulus and the border of inferior myocardial infarction may play a role in the genesis of ventricular tachycardia. We examined the frequency with which a slow conduction zone within the mitral isthmus was critical to the maintenance of ventricular tachycardia associated with remote inferior infarction in patients undergoing catheter ablation. METHODS AND RESULTS: In 4 of 12 patients, a critical zone of slow conduction was identified within the mitral isthmus. In each of these patients, two characteristic and morphologically distinct tachycardias were induced: a left bundle (rS in V1, R in V6), left superior axis morphology and a right bundle (R in V1, QS in V6), right superior axis morphology (cycle length, 610 to 320 ms). In each patient, a zone of slow conduction, shared by both morphologies, was characterized by diastolic potentials with electrogram-QRS intervals of 85 to 161 ms (21% to 47% of tachycardia cycle length) and entrainment with concealed fusion during pacing associated with stimulus-QRS intervals of 81 to 400 ms (20% to 91% of tachycardia cycle length). In each patient, a single radiofrequency energy application at the shared site of slow conduction eliminated inducibility of both morphologies. During follow-up of 1 to 11 months, no patient had recurrent tachycardia. CONCLUSIONS: The mitral isthmus contains a critical region of slow conduction in some patients with ventricular tachycardia after inferior myocardial infarction, providing a vulnerable and anatomically localized target for catheter ablation. Characteristic tachycardia morphologies may provide clinical markers for this underlying mechanism.

Cardiac Catheterization↗

PubMed1995

Predictors of defibrillation energy requirements with nonepicardial lead systems.

The determinants of high defibrillation energy requirements (DER) using nonepicardial lead systems (NELS) have not been well characterized. The goal of this study was to examine prospectively the influence of clinical, radiographic, echocardiographic, and procedural variables on DER during NELS placement. Data from 100 consecutive patients undergoing attempted NELS implantation were analyzed. Transvenous leads, subcutaneous patches, and monophasic shock devices from two manufacturers were used. Leads were successfully positioned for testing in 95% of patients. An adequate DER (< or = 25 J) was obtained in 73 of 95 (77%) of patients. Univariate analysis identified amiodarone therapy and left ventricular mass as predictors of high DER. With multivariate analysis, amiodarone therapy was the sole significant predictor of high DER (P = 0.002, odds ratio 5.46). The 22 patients with high NELS DER also had high epicardial DER (mean 24 +/- 9 J). The two patch epicardial DER was > 25 joules in 12 of 22 patients. Thus, adequate DER with monophasic shock waveforms can be obtained in most patients undergoing NELS testing. However, amiodarone therapy significantly increases the probability of obtaining high DER.

Amiodarone↗