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Biomedical subjects

E N Prystowsky

Publications and source records attributed to E N Prystowsky.

At least 19 recordsLinked to original sources
PubMed1992

Effects of bepridil on cardiac electrophysiologic properties.

The current classification system for antiarrhythmic drugs has several shortcomings; for example, electrophysiologic effects are defined in normal tissue, whereas antiarrhythmic drugs are often used clinically in diseased or injured tissue. Consideration of the electrophysiologic effects of bepridil in humans emphasizes the drawbacks of the classification system. Bepridil is primarily a calcium antagonist with class IV action. However, because the drug has class IA action as well, it should not be considered a typical class I or class IV agent. Bepridil has been observed to prolong the QT interval in the majority of patients in whom it is used for treatment of angina. However, in US clinical trials, including open extensions, only 7 cases of torsades de pointes have been recorded. In France, where the drug is approved for treatment of angina, the incidence of torsades de pointes was 0.01% in 1989. No consensus currently exists regarding what degree of QT prolongation constitutes increased risk for a ventricular proarrhythmic event. Based on current information, bepridil should be used cautiously in patients with a propensity toward hypokalemia, which can exacerbate or induce a proarrhythmic state. The drug should not be used in patients with a prolonged QT interval at baseline, a history of torsades de pointes, or long QT interval syndrome. Bepridil also should be avoided in patients with sinus node dysfunction or second- or third-degree atrioventricular block.

Arrhythmias, Cardiac↗
PubMed1992

New observations on atrial fibrillation before and after surgical treatment in patients with the Wolff-Parkinson-White syndrome.

The records of 342 patients who received surgical treatment for the Wolff-Parkinson-White syndrome between 1968 and 1986 were reviewed to evaluate the characteristics of atrial fibrillation. The patients were classified into two groups according to the presence (n = 166) or absence (n = 176) of documented episodes of atrial fibrillation preoperatively. The mean follow-up duration was 6 years (range 2 to 20). As compared with reports based on smaller patient groups and shorter follow-up, the study revealed several new findings. 1) During follow-up, nine patients in the atrial fibrillation group developed recurrent atrial fibrillation after a successful operation; five of these nine patients did not have associated heart disease. 2) All three patients with a history of atrial fibrillation and an accessory pathway conducting in the anterograde direction only had a successful surgical procedure and no postoperative atrial fibrillation. 3) The cycle length of atrioventricular (AV) reciprocating tachycardia was significantly shorter in the atrial fibrillation group (304 +/- 42 ms, mean +/- SD) than in the no-atrial fibrillation group (321 +/- 54 ms, p less than 0.005), and the cycle length of AV reciprocating tachycardia that degenerated into atrial fibrillation (289 +/- 26 ms) was shorter than that for the AV reciprocating tachycardia without subsequent atrial fibrillation (316 +/- 51 ms, p less than 0.005). 4) Sustained atrial fibrillation was induced in 30% of patients without a history of atrial fibrillation. 5) Atrial fibrillation occurred in four patients with an accessory pathway that conducted only in the retrograde direction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Bedside termination of sustained ventricular tachycardia by transesophageal atrial pacing.

Transesophageal atrial pacing was used to terminate hemodynamically stable sustained monomorphic ventricular tachycardia in two patients. The procedure was performed at the bedside, no anesthesia was required, there were no complications, and one of the patients went home after the procedure was performed. This method should be considered prior to using direct current cardioversion in patients with hemodynamically stable sustained monomorphic ventricular tachycardia.

Aged↗
PubMed1992

Physiological substrate for antidromic reciprocating tachycardia. Prerequisite characteristics of the accessory pathway and atrioventricular conduction system.

BACKGROUND: Although the anatomic "substrate" for the occurrence of antidromic reciprocating tachycardia (ART) has been previously examined, the underlying physiological substrate for this unusual arrhythmia in patients with the Wolff-Parkinson-White syndrome has not been thoroughly characterized. METHODS AND RESULTS: The electrophysiological properties of the accessory pathway and normal ventriculoatrial conduction system in 30 patients with ART and a single accessory pathway were compared with those observed in a control group of 36 patients without this arrhythmia to elucidate the critical physiological substrate essential for the development and maintenance of ART. Inducible ART had a mean cycle length of 286 +/- 31 msec. The average retrograde ventriculoatrial conduction system effective refractory period in ART patients was significantly less than that in the control group (244 +/- 32 versus 291 +/- 46 msec, p = 0.0002). All of the ART patients showed retrograde conduction over the normal conduction system at cycle lengths of less than or equal to 360 msec; 23 had 1:1 conduction to less than or equal to 300 msec, and 16 showed 1:1 propagation at cycle lengths of less than or equal to 260 msec. The shortest cycle length accompanied by 1:1 retrograde propagation over the normal conduction system in patients with ART was also significantly less than that observed in the control group (274 +/- 39 versus 347 +/- 73 msec, p less than 0.001). The accessory pathway anterograde ERP in ART patients with 1:1 retrograde conduction over the normal ventriculoatrial conduction system at cycle lengths of less than or equal to 360 was significantly less than that seen in comparable control patients (247 +/- 23 versus 284 +/- 56 msec, p = 0.001), and the accessory pathway location was significantly further from the atrioventricular node in 21 patients with ART undergoing surgery than that in 22 operated control patients (3.8 +/- 0.8 versus 2.9 +/- 0.8 mapping units, p = 0.0025) who also had retrograde ventriculoatrial conduction to cycle lengths of less than or equal to 360 msec. No significant differences in anterograde atrioventricular conduction system properties, retrograde accessory pathway refractoriness, or shortest ventricular pacing cycle lengths maintaining 1:1 conduction via the accessory pathway were observed between groups. CONCLUSIONS: This quantitative characterization of the properties of conduction and refractoriness of both the accessory pathway and ventriculoatrial conduction system and the relation between these characteristics and the accessory pathway location in ART patients provides additional insight into the prerequisites for the initiation and maintenance of this rhythm disturbance.

Adult↗
PubMed1992

Effect of Ebstein's anomaly on short- and long-term outcome of surgically treated patients with Wolff-Parkinson-White syndrome.

BACKGROUND: Ebstein's anomaly is the most commonly occurring congenital abnormality associated with the Wolff-Parkinson-White (WPW) syndrome. However, the effects of Ebstein's anomaly on the risks and benefits of surgical ablation of accessory pathways in patients with WPW syndrome are unknown. METHODS AND RESULTS: This study compared the long-term outcome of 38 WPW patients with Ebstein's anomaly undergoing accessory pathway ablation to a reference population of 384 similarly treated patients without the anomaly. Ebstein's anomaly was mild in 21 patients (55%) and moderate-to-severe in 17 patients (45%). Sixteen patients (42%) required tricuspid valve surgery, and 23 (61%) had an atrial septal defect or patent foramen ovale repaired. Baseline clinical characteristics and preoperative clinical arrhythmias were similar in both groups. Ten-year survival was 92.4% and 91.2% for patients with and without Ebstein's anomaly, respectively (p = NS). During a mean follow-up of 6.2 +/- 3.8 and 5.3 +/- 3.6 years, 82% of patients with and 90% without Ebstein's anomaly had either clinically insignificant or no arrhythmias, and 18% versus 10% reported symptoms suggesting arrhythmias lasting longer than 1 minute, respectively. Atrial fibrillation was reduced postoperatively to 9% (p less than 0.001) in patients with and to 4% (p less than 0.001) in those without the anomaly. Fewer hospitalizations were reported postoperatively by 90% versus 96% of patients with and without Ebstein's anomaly; 9.4% versus 6.0% of patients were disabled at follow-up, respectively (p = NS). CONCLUSIONS: Patients with Ebstein's anomaly are improved significantly after accessory pathway ablation. The presence of this anomaly should not preclude accessory pathway ablation in these patients.

Adolescent↗
PubMed1992

Antiarrhythmic drug therapy in the management of cardiac arrest survivors.

Antiarrhythmic drugs may be used as primary therapy to prevent recurrent cardiac arrest or as adjunctive treatment in patients given an implantable cardioverter defibrillator. In the latter instance, drugs are given to suppress nonlethal arrhythmias that are capable of initiating defibrillator discharge or to slow and/or decrease the number of episodes of sustained ventricular tachyarrhythmias. When used as primary therapy, drug efficacy should be judged by nonempirical methods, preferably serial electrophysiological testing. Although no study has compared noninvasive with invasive testing to determine antiarrhythmic drug effectiveness in a substantial number of cardiac arrest survivors, several investigations have demonstrated that electrophysiological testing is useful for this purpose. One important limitation of serial electrophysiological testing is that nearly 40% of cardiac arrest survivors do not have a sustained ventricular tachyarrhythmia initiated at baseline study; nonpharmacological treatment would appear preferable in these patients. Further, since a relatively high arrhythmic recurrence rate has been noted in individuals with suppressible sustained ventricular tachycardia/fibrillation during drug therapy and a left ventricular ejection fraction less than 30%, we recommend serial electrophysiological/pharmacological testing primarily for patients with inducible sustained ventricular tachyarrhythmias with an ejection fraction greater than or equal to 30%.

Amiodarone↗
PubMed1991

Role of concealed and supernormal conductions during atrial fibrillation in the preexcitation syndrome.

The hypothesis that retrograde concealed and anterograde supernormal conductions over the accessory pathway are determinants of anterograde accessory pathway conduction during atrial fibrillation (AF) was prospectively tested. For 17 patients during AF, 90 +/- 13 (mean +/- standard deviation) consecutive beats were analyzed for morphology and VV interval preceding each QRS complex. In 15 patients with both preexcited and normal QRS complexes, after normal complexes, the cycle length preceding the first preexcited QRS complex was 389 +/- 69 ms, which was longer than the average cycle length of consecutive preexcited complexes (325 +/- 55 ms; p = 0.001). The mean difference was 61 +/- 53 ms. After preexcited QRS complexes, the cycle length preceding the first normal QRS complex averaged 423 +/- 65 ms, which was significantly longer than the average cycle length of 345 +/- 47 ms between consecutively conducted normal QRS complexes (p less than 0.001). The mean difference was 86 +/- 45 ms. These findings suggest retrograde concealed conduction of normally conducted QRS complexes to the accessory pathway can affect anterograde conduction over the accessory pathway, and vice versa. In 2 patients with multiple accessory pathways, 1 accessory pathway conducted only after short preceding cycle lengths (355 to 360 and 181 to 185 ms), which was consistent with supernormal conduction. In conclusion, retrograde concealed conduction to the accessory pathway conduction are factors that, in part, determine accessory and anterograde supernormal accessory pathway conduction are factors that, in part, determine accessory pathway conduction during AF.

Atrial Fibrillation↗
PubMed1991

Electrophysiologic and anatomic characteristics of ventricular tachycardia induced at the right ventricular outflow tract but not at the apex.

The site of ventricular stimulation is an important variable in the initiation of ventricular tachycardia (VT) by programmed ventricular stimulation. Among 169 patients studied consecutively, 17 (10%) had ventricular tachycardia induced by programmed electrical stimulation from the right ventricular outflow tract but not from the apex. Fourteen of these 17 patients had had prior myocardial infarction (12 had inferior, and two had both inferior and anterior myocardial infarction), two had a dilated cardiomyopathy, and one had a localized cardiomyopathy. Fourteen patients had echocardiograms suitable for analysis. Of these, 12 had posterior/inferior ventricular wall motion abnormalities located at the base of the heart. The ventricular effective refractory periods from the right ventricular outflow tract and right ventricular apex were 237 +/- 4 and 244 +/- 5 msec, respectively (p less than 0.05, mean +/- SEM). Induced VT had a cycle length of 229 +/- 4 msec and had the morphology of right bundle branch block in 12 patients, of left bundle branch block in three patients, and had both morphologies in two patients. In 14 patients the axis was superior. VT was initiated with two extrastimuli in 15 patients and with burst right ventricular pacing in two patients. Similar pacing techniques with identical pacing intervals did not induce VT at the right ventricular apex in 14 of these 17 patients. Further, among the 15 patients whose VT was induced at the right ventricular outflow tract with two extrastimuli, neither burst pacing (n = 13) nor two extrastimuli introduced at faster paced rates (n = 12) induced VT at the right ventricular apex.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Pacing, Artificial↗
PubMed1991

Syncope secondary to paroxysmal high grade AV block in a heavily trained man.

J.B. is a well-trained male with syncope due to paroxysmal AV nodal heart block who ultimately required a permanent pacemaker despite an initial attempt at cessation of training only. Baseline sinus node function was normal, but AV nodal conduction remained abnormal even after autonomic blockade supporting intrinsic AV nodal dysfunction. This case illustrates that vigorous physical training may unmask previously unrecognized intrinsic dysfunction of AV nodal conduction or, as previously reported for physical training induced sinus node dysfunction, cause AV nodal dysfunction. Simple cessation of training to treat this problem is often recommended but may not be adequate for some patients who remain at risk for recurrent syncope during the deconditioning period.

Autonomic Nervous System↗
PubMed1991

Effect of continuous enhanced vagal tone on atrioventricular nodal and sinoatrial nodal function in humans.

A constant intravenous infusion of phenylephrine (0.74 +/- 0.41 micrograms/kg/min) was given to 10 patients to cause a continuous augmentation in reflex vagal tone. After the infusion, the diastolic blood pressure increased from 76 +/- 7 to 89 +/- 11 mm Hg (p less than 0.01). The sinus cycle length and atrial-His (AH) interval were measured, and incremental atrial pacing was performed before and during phenylephrine infusion until atrioventricular (AV) nodal block was achieved. For each patient, the AV nodal function curve (i.e., the AH interval plotted as a function of the atrial pacing cycle length) was compared during both the control state and phenylephrine infusion; the AH intervals during each condition at chosen short (AHS) and long (AHL) cycle lengths were compared. The sinus cycle length increased during phenylephrine infusion from 941 +/- 294 to 1,115 +/- 347 msec (p = 0.013). The AH interval during sinus rhythm was not significantly prolonged (77 versus 82 msec, p = NS). The shortest atrial pacing cycle length yielding 1:1 AV nodal conduction increased during phenylephrine infusion from 412 +/- 120 to 575 +/- 211 msec (p less than 0.01). Of note, the degree of sinus cycle length prolongation did not correlate with the degree of prolongation in the shortest atrial pacing cycle length yielding 1:1 AV nodal conduction. The AV nodal function curve was shifted markedly to the right and only slightly upward.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Occurrence of atrial fibrillation in patients with paroxysmal supraventricular tachycardia due to atrioventricular nodal reentry.

The occurrence of atrial fibrillation in patients with paroxysmal supraventricular tachycardia (PSVT) has been well documented when PSVT is secondary to atrioventricular reentry, but not when PSVT is secondary to atrioventricular nodal reentry (AVNRT). Seventeen patients with AVNRT were followed using transtelephonic electrocardiogram monitoring to document symptomatic tachycardias. The median length of telephone monitor surveillance was 357 days. Fifteen of 17 patients transmitted electrocardiograms that showed PSVT. Three of 17 patients (18%) transmitted electrocardiograms that showed atrial fibrillation. A transition from PSVT into atrial fibrillation was not recorded, but all three did have PSVT recorded on other days of follow-up. We report the occurrence of atrial fibrillation in patients with AVNRT and that its incidence is higher than expected for the general population.

Atrial Fibrillation↗
PubMed1990

Nonpharmacologic treatment of the Wolff-Parkinson-White syndrome and other supraventricular tachycardias.

Nonpharmacologic treatment using surgery or intracardiac catheter ablation can be used for several forms of supraventricular tachycardia. Surgery is highly successful in preventing recurrent tachyarrhythmias in patients with the Wolff-Parkinson-White syndrome and can be recommended as first-line treatment in several situations. Catheter ablation of the atrioventricular conduction system combined with an implanted ventricular pacemaker can offer substantial relief to selected patients with drug-refractory atrial fibrillation. Technical advances in catheter ablation will undoubtedly lead to more widespread use of this form of therapy in supraventricular tachycardia.

Cardiac Catheterization↗