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Biomedical subjects

E N Prystowsky

Publications and source records attributed to E N Prystowsky.

179 records · Page 10Linked to original sources
PubMed1980

Studies with aprindine.

Aprindine is a very effective antiarrhythmic agent with a narrow therapeutic-toxic ratio. It has been used successfully in treating patients who have both supraventricular and ventricular tachyarrhythmias. Aprindine slows conduction in all cardiac fibers and suppresses digitalis-induced after-depolarizations. Voltage-clamp studies indicate that aprindine, in higher doses, suppresses the slow inward current in frog atria. In the dog subjected to coronary artery occlusion, aprindine may be arrhythmogenic, antiarrhythmic, or have no effect on the development of arrhythmias, depending on the temporal relationship between time of administration and time of occlusion.

Agranulocytosis↗
PubMed1980

'Dual atrioventricular nodal pathways" in patients with Wolff-Parkinson-White syndrome.

'Dual atrioventricular nodal pathways" were found in five patients who also had the Wolff-Parkinson-White syndrome. All five patients had a re-entrant tachycardia that used the atrioventricular node for conduction in the anterograde direction and an accessory atrioventricular pathway for conduction in the retrograde direction. One of the patients also had a re-entrant tachycardia that originated within the atrium or the atrioventricular node. Dual atrioventricular nodal pathways were identified in three of the five patients during their first electrophysiological study because the effective refractory period of the accessory atrioventricular pathway in the anterograde direction was longer than the effective refractory period of the fast atrioventricular nodal pathway. In the other two patients the dual atrioventricular nodal pathways were found only after operative division of an accessory atrioventricular pathway. Re-entrant tachycardia that uses an accessory pathway may be cured by operative division of the accessory pathway. Tachycardia resulting from re-entry within the atrioventricular node cannot be cured by an operation unless the normal conduction system is divided and a permanent pacemaker implanted. These five patients indicate the importance of determining the aetiology of tachycardia by studying the tachycardia itself and not only the type of atrioventricular conduction present.

Atrioventricular Node↗
PubMed1980

Origin of the atrial electrogram recorded from the esophagus.

The purpose of this study was to ascertain the origin of the atrial electrogram recorded on the esophageal lead. The atria and esophagus were mapped during reciprocating tachycardia in 11 patients with the Wolff-Parkinson-White syndrome and one patient with atrioventricular nodal reentry, and during right ventricular pacing in four additional patients. The esophagus was mapped by recording atrial electrograms at 1-cm intervals throughout the esophagus beginning at the most distal area where atrial depolarization was seen. The retrograde atrial activation time recorded on the esophageal lead in its distal position occurred at the same time as atrial septal depolarization in all patients. In 14 of 16 patients, the distal esophageal ventriculoatrial (VA) conduction time was also the shortest esophageal VA conduction time recorded. In two of five patients with left lateral accessory pathways, the shortest esophageal VA conduction time was noted during pullback of the lead from the esophagus instead of at the most distal area. The most likely explanation for this was an unusual anatomic relationship between the esophagus and left atrium in these two patients. We conclude that 1) the most distal esophageal atrial electrogram probably records posterior paraseptal atrial depolarization; 2) it is unusual to record clearly identifiable left atrial activation in the esophagus; and 3) the esophageal lead is not useful in locating left-sided accessory pathways.

Atrioventricular Node↗
PubMed1979

The natural history of conduction system disease in myotonic muscular dystrophy as determined by serial electrophysiologic studies.

To evaluate the progression of conduction system disease in myotonic muscular dystrophy, nine patients underwent serial electrophysiologic studies at a mean of 35 months apart. At the initial study, seven patients had first-degree atrioventricular block and three of these seven had disease in the His-Purkinje system (HV greater than 55 msec). At the second study, seven patients had prolonged HV intervals, and during the almost 3-year period, HV intervals increased by at least 5 msec in all seven patients. No electrophysiologic or electrocardiographic measures could be found that correlated with progression of conduction disease in these patients. Because of the failure of electrophysiologic measures to predict progression of conduction disease in these patients, electrophysiologic studies are recommended only for symptomatic patients. If significant disease is found in either impulse formation or conduction, permanent pacemaker therapy is warranted.

Adult↗
PubMed1979

Atypical patterns of retrograde conduction over accessory atrioventricular pathways in the Wolff-Parkinson-White syndrome.

Patterns of ventriculoatrial conduction have been used to distinguish retrograde conduction over an accessory atrioventricular pathway from that over the normal atrioventricular conduction system. Ventriculoatrial conduction at a constant interval during incremental ventricular pacing and during progressive prematurity of ventricular extrastimuli has been considered characteristic of conduction over an accessory pathway. We describe three patients with the Wolff-Parkinson-White syndrome who had progressive or sudden increments in ventriculoatrial conduction over an accessory pathway during fixed-rate ventricular pacing or during introduction of ventricular extrastimuli. Such properties have been considered characteristic of conduction over the normal atrioventricular conduction system. We conclude that retrograde conduction over accessory pathways may resemble conduction over the normal atrioventricular conduction system.

Adult↗
PubMed1979

An analysis of the effects of acetylcholine on conduction and refractoriness in the rabbit sinus node.

The effects of acetylcholine (ACh) on sinus node automaticity, atrio-sinus conduction, and refractoriness were studied in 41 isolated rabbit right atrial preparations. Average control rate was 126 beats/min, and ACh 5 x 10(-8) M, 5 x 10(-7) M, and 5 x 10(-6) M significantly decreased heart rate by 7, 15, and 43%, respectively (P less than 0.01, 0.001, and 0.001). Atrio-sinus conduction time at a pacing cycle length of 400 msec did not significantly change during exposure to ACh 5 x 10(-8) and 5 x 10(-7) M. However, the mean effective refractory period (ERP) of the sinus node, at a pacing cycle length of 400 msec, increased from 183 +/- 16 msec to 210 +/- 24 msec during exposure to ACh 5 x 10(-7) M (P less than 0.025). The change in ERP followed the change in action potential duration. In contrast to the lack of effect of ACh 5 x 10(-7) M on atrio-sinus conduction time, ACh 5 x 10(-6) M caused 2:1 atrio-sinus block in 8 of 10 experiments. The site of block was identified using multiple microelectrode impalements, and occurred between the perinodal fibers bordering on the edge of the sinus node and the pacemaker area in the sinus node proper. When the pacing cycle length was increased and 1:1 atrio-sinus conduciton was present, conduction time did not significantly differ from control. At this longer pacing cycle length the mean ERP of the sinus node was 380 msec greater than control and lasted well after repolarization was completed. Thus, atrio-sinus block during exposure to ACh 5 x 10(-6) M resulted from a marked prolongation of refractoriness.

Acetylcholine↗
PubMedDate not supplied

Predicting the outcomes of electrophysiologic studies of patients with unexplained syncope: preliminary validation of a derived model.

PURPOSE: To develop and validate a predictive model that would allow clinicians to determine whether an electrophysiologic (EP) study is likely to result in useful diagnostic information for a patient who has unexplained syncope. PATIENTS: One hundred seventy-nine consecutive patients with unexplained syncope who underwent EP studies at two university medical centers comprised the training sample. A test sample to validate the model was made up of 138 patients from the clinical literature who had undergone EP studies for syncope. DESIGN: Retrospective analysis of patients undergoing EP studies for syncope. The data collector was blinded to the study hypothesis; the electrophysiologist assessing outcomes was blinded to clinical and historical data. Clinical predictor variables available from the history, the physical examination, electrocardiography (ECG), and Holter monitoring were analyzed via two multivariable predictive modeling strategies (ordinal logistic regression and recursive partitioning) for their abilities to predict the results of EP studies, namely tachyarrhythmic and bradyarrhythmic outcomes. These categories were further divided into full arrhythmia and borderline arrhythmia groups. RESULTS: Important outcomes were 1) sustained monomorphic ventricular tachycardia (VT) and 2) bradyarrhythmias, including sinus node and atrioventricular (AV) conducting disease. The results of the logistic regression (in this study, the superior strategy) showed that the presence of organic heart disease [odds ratio (OR) = 3.0, p less than 0.001] and frequent premature ventricular contractions on ECG (OR = 6.7, p less than 0.004) were associated with VT, while the following abnormal ECG findings were associated with bradyarrhythmias: first-degree heart block (OR = 7.9, p less than 0.001), bundle-branch block (OR = 3.0, p less than 0.02), and sinus bradycardia (OR = 3.5, p less than 0.03). Eighty-seven percent of the 31 patients with important outcomes at EP study had at least one of these clinical risk factors, while 95% of the patients with none of these risk factors had normal or nondiagnostic EP studies. In the validation sample, the presence of one or more risk factors would have correctly identified 88% of the test VT patients and 65% of the test bradyarrhythmia patients as needing EP study. CONCLUSION: These five identified predictive factors, available from the history, the physical examination, and the initial ECG, could be useful to clinicians in selecting those patients with unexplained syncope who will have a serious arrhythmia identified by EP studies.

Arrhythmias, Cardiac↗
PubMedDate not supplied

Prevention of sudden death in patients with coronary artery disease: the Multicenter Unsustained Tachycardia Trial (MUSTT).

This trial will significantly advance our understanding of the prognostic and therapeutic usefulness of electrophysiologic studies in patients with coronary artery disease. Several features of this trial are worth emphasizing. First, the protocol for performing programmed stimulation and serial drug testing is designed to mirror those currently in use by many practicing electrophysiologists. While practice patterns vary, the procedures used in the trial reflect what is considered "usual and standard" practice. Second, because half of the patients with inducible sustained ventricular tachycardia will be given no antiarrhythmic therapy, we will be able to ascertain the true risk of sudden death in this patient population without the influence of these agents. Third, this trial will assess the usefulness of a method of guiding antiarrhythmic therapy (electrophysiologic testing) to reduce mortality in this high-risk population. It will not evaluate the efficacy of a specific type of antiarrhythmic therapy.

Amiodarone↗
PubMedDate not supplied

New drugs for treatment of ventricular arrhythmias.

This article has attempted to review selected clinical features of new antiarrhythmic agents for treatment of recurrent ventricular tachycardia and ventricular fibrillation. While it is apparent that the ideal antiarrhythmic agent does not exist, whether it be a new or old antiarrhythmic drug, effective and safe antiarrhythmic drug therapy can nevertheless be administered to many patients if the pharmacologic principles and properties described herein are carefully considered.

Amiodarone↗