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Biomedical subjects

S Milstein

Publications and source records attributed to S Milstein.

At least 55 records · Page 3Linked to original sources
PubMed1989

Accelerated idioventricular rhythm complicating atrioventricular junction ablation for automatic atrial tachycardia.

A 13-year-old male with histologic evidence of cardiomyopathy, drug-refractory primary atrial tachycardias, and deteriorating left ventricular function underwent transcatheter His bundle ablation to control ventricular rate. Following an initial successful ablation at the level of the atrioventricular node, the patient exhibited an accelerated escape rhythm of apparent junctional origin (ventricular cycle length = 470 msec, HV = 100 msec) with complete heart block. A second ablation procedure was undertaken, following which an accelerated idioventricular rhythm (cycle length = 500 msec) became apparent and has persisted (follow-up 15 months). Thus, findings in this patient suggest that attempts to control refractory rapid ventricular responses in cardiomyopathy patients with primary atrial tachycardias may be complicated by the potential for junctional and idioventricular sites to exhibit similar abnormally accelerated subsidiary pacemaker function.

Adolescent↗
PubMed1989

Cardiac asystole: a manifestation of neurally mediated hypotension-bradycardia.

It has been proposed that prolonged cardiac asystole mimicking an episode of sudden cardiac death may occur as a manifestation of neurally mediated hypotension-bradycardia syndrome. To assess this possibility, electrocardiographic and hemodynamic findings during upright tilt testing were evaluated in six survivors of suspected asystolic sudden cardiac arrest with normal conventional electrophysiologic evaluation (Group I). These observations were compared with findings in two control groups: six patients with syncope but without evident asystole and with normal conventional electrophysiologic evaluation but demonstrable neurally mediated hypotension-bradycardia (Group II), and six patients with syncope in whom conventional electrophysiologic evaluation provided a presumptive diagnosis (Group III). Patients in all three groups ranged in age from 16 to 59 years. During head-up tilt testing (either alone or with isoproterenol infusion), patients in both Groups I and II developed syncope in less than or equal to 5 min, whereas patients in Group III remained asymptomatic. Patients in Groups I and II exhibited a similar tilt-induced decrease in mean arterial pressure (-46 +/- 9 and -40 +/- 9 mm Hg, respectively, p = NS) and heart rate (-44 +/- 28 and -49 +/- 12 beats/min, respectively, p = NS). In contrast, patients in Group III manifested only a moderate decrease in mean arterial pressure (-14 +/- 5 mm Hg) and had an increase in heart rate (+14 +/- 8 beats/min). Both mean arterial pressure and heart rate changes in Group I and Group II patients differed significantly (p less than 0.001) from values in Group III patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Cardiac electrophysiologic effects of orally administered DPI 201-106 in conscious canines: effects of pharmacologic autonomic blockade or cardiac transplantation.

This study assessed the cardiac electrophysiologic effects of DPI 201-106 (DPI), a novel orally absorbable positive inotropic agent, the administration of which has been associated with electrocardiographic (ECG) QT and T-wave changes. In the intact conscious dog, oral administration of both 8 and 16 mg/kg DPI produced marked sinus cycle length prolongation (8 mg/kg, + 11%; 16 mg/kg, + 9%) within 60 min of DPI administration (p less than 0.05 vs. baseline). DPI also tended to prolong right atrial refractory periods, and increase sinus node recovery time. In addition, DPI exhibited a negative dromotropic effect on the atrioventricular (AV) node, prolonging both AV node effective and functional refractory periods and tending to increase the minimum atrial paced cycle length at which AV conduction of 1:1 was maintained. DPI also significantly increased right ventricular effective refractory period (ERP) at both doses studied and increased ventricular functional refractory period (FRP) at the 16-mg/kg dose. Finally, although DPI administration was associated with QT interval prolongation, this effect was slight when corrected for sinus cycle length (SCL) (QTc, +3%). When administered concomitantly with propranolol and atropine or after surgical cardiac denervation, DPI-induced electrophysiologic changes were largely attenuated or abolished. Thus, findings in this study indicate that the apparent cardiac electrophysiologic effects of DPI are predominantly of neurally mediated origin in this animal model.

Administration, Oral↗
PubMed1987

Role of extrastimulus site and tachycardia cycle length in inducibility of atrial preexcitation by premature ventricular stimulation during reciprocating tachycardia.

Preexcitation of the atria during reciprocating tachycardia (RT) by a premature ventricular complex occurring when the His bundle is refractory provides direct evidence of the presence of accessory atrioventricular (AV) connection. The impact of ventricular stimulation site and RT cycle length on inducibility of atrial preexcitation was assessed in 38 patients with RT utilizing a single accessory AV connection (right free wall in 5 patients, left free wall in 21 and posterior septal/paraseptal in 12). Extrastimuli were inserted at right ventricular (RV) apical, left ventricular (LV) septal and LV free wall sites. Inducibility of and magnitude of atrial preexcitation increased as stimulation site approached accessory AV connection site. Thus, for RV free wall connections, RV extrastimuli preexcited the atria in 5 of 5 patients, LV septal in 1 of 5 and LV free wall in 0 of 4. For LV free wall accessory connections, RV extrastimuli preexcited the atria in only 3 of 21 patients, compared with 12 of 17 with LV septal and 20 of 21 with LV free wall stimulation. Additionally, the magnitude of atrial preexcitation achieved was related to RT cycle length, diminishing as cycle length shortened. Finally, in a few instances both RV apical and LV free wall extrastimuli failed to elicit preexcitation in patients with a posterior septal connection. Thus, ventricular pacing site and RT cycle length contribute importantly to induction of atrial preexcitation by ventricular extrastimulation technique and should be considered during evaluation of patients with RT in whom accessory AV connections may be present.

Adolescent↗
PubMed1987

Relation between clinical presentation and induced arrhythmias in the Wolff-Parkinson-White syndrome.

Electrophysiologic testing is warranted in patients with the Wolff-Parkinson-White (WPW) syndrome presenting with rapid atrial fibrillation (AF) or ventricular fibrillation. Indications are less clear in patients presenting only with atrioventricular reentrant tachycardia (ART). A knowledge of propensity of this latter group to show a rapid ventricular response in the event of AF and the ability of electrophysiologic testing to reproduce the type and rate of clinical arrhythmias are relevant to this decision. The records of 126 symptomatic patients with manifest WPW syndrome were reviewed and separated into 4 groups according to presentation: group 1--AF; group 2--ART; group 3--palpitations suggesting ART; and group 4--AF and ART. All patients except those in group 3 had electrocardiographically documented clinical arrhythmias, and these arrhythmias were compared with those induced during electrophysiologic testing. The shortest RR interval during induced AF and the cycle length of induced ART correlated well with those occurring clinically (r = 0.72, p less than 0.00001), as did the cycle length of induced ART (r = 0.79, p less than 0.00001). Patients presenting with AF (65%) had a higher incidence of atrial vulnerability (48%) and sustained AF at electrophysiologic testing than those presenting with ART (16% and 5%) or undocumented palpitations (27% and 21%). Forty-one percent of patients with ART and 51% with undocumented palpitations had potentially lethal rates (shortest RR interval less than 250 ms) during induced AF. The ability to reproduce clinical arrhythmias and the frequency of rapid rates during AF induced in patients presenting with only ART or undocumented palpitations supports the recommendation for electrophysiologic testing in symptomatic patients with WPW.

Adult↗
PubMed1987

Comparison of the ventricular response during atrial fibrillation in patients with enhanced atrioventricular node conduction and Wolff-Parkinson-White syndrome.

Although ventricular fibrillation is a well known sequel to atrial fibrillation in the Wolff-Parkinson-White syndrome, ventricular fibrillation is not generally associated with supraventricular tachycardia in the presence of enhanced atrioventricular (AV) node conduction without pre-excitation. It was hypothesized that the ventricular response during atrial fibrillation may be less in patients with enhanced AV node conduction than in their counterparts with Wolff-Parkinson-White syndrome matched for anterograde effective refractory period. Slower ventricular rates during atrial fibrillation would suggest an increased propensity for concealed conduction in the enhanced AV node conduction group than in the group with an accessory pathway. Three groups of patients aged 16 to 65 years underwent electrophysiologic testing for supraventricular tachycardia or after surgical correction of Wolff-Parkinson-White syndrome. Sixteen patients had enhanced AV node conduction, 16 had Wolff-Parkinson-White syndrome and 16 had normal AV node conduction. Patients with enhanced AV node conduction and Wolff-Parkinson-White syndrome were well matched for anterograde effective refractory period (245 +/- 22 versus 258 +/- 25 ms) and minimal cycle length, maintaining 1:1 anterograde conduction (261 +/- 21 versus 260 +/- 40). There was no difference in intervals during atrial fibrillation (average RR interval = 372 +/- 37 versus 346 +/- 66) or shortest RR interval (266 +/- 27 versus 243 +/- 51). Thus, patients with Wolff-Parkinson-White syndrome and those with enhanced AV node conduction matched for anterograde refractory period exhibit similar ventricular rates during atrial fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

An algorithm for the electrocardiographic localization of accessory pathways in the Wolff-Parkinson-White syndrome.

Accessory pathway location in the Wolff-Parkinson-White syndrome influences the success and morbidity of nonpharmacological therapies, so that an estimate of accessory pathway location is relevant to the practicing physician. We derived an algorithm for accessory pathway localization based on the surface electrocardiogram; we tested it in a population of 141 patients with the Wolff-Parkinson-White syndrome in whom accessory pathway localization was made by electrophysiological and/or intraoperative mapping. The goal of the algorithm was to localize the accessory pathway to one of four anatomic regions, namely, left free wall, posteroseptal, anteroseptal or right free wall by using a simple, easy-to-apply scheme. Each of two observers, blinded to the results of mapping, correctly identified the anatomic location of 91% and 90% of pathways, respectively. We conclude that a simple algorithm utilizing the 12-lead electrocardiogram can provide a valuable first approximation of accessory pathway location in the Wolff-Parkinson-White syndrome.

Adult↗
PubMed1987

Sensor-triggered, rate-variable cardiac pacing. Current technologies and clinical implications.

Conventional implantable dual-chamber cardiac pacemakers adjust heart rate and maintain normal atrial and ventricular contraction by tracking "native" atrial electrical activity and pacing the ventricles after a predetermined programmable atrioventricular delay. However, in patients with symptomatic bradyarrhythmias, optimal function of "atrial-tracking" devices may be limited by concomitant sinoatrial disease. Provision of chronotropic response during physical exertion or emotional stress may be achieved by using physiologic sensors to alter pacing rate independently of atrial activity. Additional systems using sensor technologies are being developed. Future pacing systems will have dual-chamber pacing capability and may use several sensors coupled synergistically in order to take advantage of particular strengths of each. Physiologic sensor technology may be of diagnostic value in both antitachycardia devices and implantable cardioverter and defibrillator systems.

Bradycardia↗
PubMed1987

Phase 3 and phase 4 block of the accessory pathway in Wolff-Parkinson-White syndrome--a case report.

A 12-year-old girl presented with recurrent episodes of supraventricular tachycardia. A 12 lead electrocardiogram showed normal sinus rhythm with a normal PR interval and no evidence of preexcitation. A 24 h Holter monitor showed intermittent preexcitation. Both phase 3 and phase 4 block in the accessory pathway were demonstrated with introduction of atrial extrastimuli during sinus rhythm at electrophysiology study. However, Holter recording failed to reveal a consistent relationship between coupling intervals and accessory pathway conduction. The discrepancy between the Holter monitor and the electrophysiologic study can be explained by variability of factors such as autonomic tone during the Holter recording. This case illustrates a potential mechanism for intermittent preexcitation in the Wolff-Parkinson-White syndrome.

Bradycardia↗
PubMed1986

Electrophysiologic profile of asymptomatic Wolff-Parkinson-White pattern.

Electrophysiologic testing in patients with asymptomatic Wolff-Parkinson-White syndrome (WPW) may be useful in defining arrhythmic substrates and predictors of fatality. Forty-two patients with asymptomatic WPW, mean age 36 years, underwent electrophysiologic studies and were followed prospectively. They were compared with a matched control group of patients studied within the same period for documented tachycardia associated with the WPW syndrome. Asymptomatic patients had longer anterograde effective refractory periods of the accessory pathway, longer minimum cycle lengths maintaining 1:1 conduction over the accessory pathway, longer minimum RR intervals between consecutive preexcited beats during atrial fibrillation (AF) and longer mean RR intervals during AF than their symptomatic counterparts. Sustained reciprocating tachycardia could not be induced in most patients and induction of AF required rapid atrial pacing in all patients. Nine patients had an anterograde effective refractory period of less than 270 ms and 17% had minimum cycle length less than 250 ms during induced AF. Over a follow-up of 29 +/- 18 months, 1 patient died of noncardiac causes and the rest remained asymptomatic. Thus, patients with asymptomatic WPW have deficient electrophysiologic substrates to maintain orthodromic reciprocating tachycardia under baseline conditions and do not have atrial vulnerability. Seventeen percent of patients had potentially lethal ventricular rates during induced AF.

Adolescent↗
PubMed1986

Demonstration of macroreentry and feasibility of operative therapy in the common type of atrial flutter.

Two patients are described who had recurrent and long-standing atrial flutter of the common type and were referred for electrophysiologic testing and surgical management. In both patients, atrial flutter could be initiated and terminated by programmed stimulation. Atrial endocardial mapping showed earliest activation during flutter at the orifice of the coronary sinus, with activity proceeding to the low atrial septum, high lateral right atrium and low right atrium, respectively. Programmed atrial extrasystoles from the high right atrium at a time when the atrial septal region was refractory advanced atrial flutter in proportion to prematurity of the extrastimulus, while maintaining the low to high activation sequence. Intraoperatively, epicardial atrial mapping revealed a large right atrial reentrant circuit beginning in the posteroseptal region and proceeding superiorly and laterally through the right atrial free wall before returning to its starting point. The narrowest part of the circuit and that showing relatively slow conduction during atrial flutter was observed in the low right atrial tissue between the tricuspid valve ring and the orifices of the inferior vena cava and proximal coronary sinus, respectively. Cryosurgical ablation around the orifice of the coronary sinus and surrounding atrial wall has prevented recurrent atrial flutter over short term follow-up in both patients, although 1 of the patients has required antiarrhythmic therapy for postoperative atrial fibrillation.

Atrial Fibrillation↗
PubMed1986

Closed-heart technique for Wolff-Parkinson-White syndrome: further experience and potential limitations.

We have described a closed-heart technique for division of atrioventricular (AV) pathways in Wolff-Parkinson-White (WPW) syndrome. The technique involves dissection and mobilization of the AV fat pad with exposure and cryoablation of the AV junction at the site of the AV pathways. One hundred five consecutive patients with WPW syndrome with left ventricular free wall (74), posterior septal (23), and right ventricular free wall AV pathways (11) were operated on between July, 1982, and September, 1985. Three patients had multiple accessory pathways, and 9 had associated cardiac disease. Electrophysiological testing to determine the presence and site of the AV pathway was performed before and after dissection of the fat pad and again after cryoablation of the AV junction. All AV pathways but 1 were successfully ablated. There were no deaths and no incident of AV block. One hundred four patients remain free from arrhythmia in the absence of drugs after a mean follow-up of 18 months (range, 2 to 42 months). Four patients required a second operation within the first few weeks for recurrence of AV pathway conduction, and 1 patient required a third operation. In 3 of these patients, AV pathway conduction persisted after extensive dissection and exposure of the AV junction and disappeared only after cryoablation. Recurrence of AV pathway conduction in the latter patients suggests the presence of a subendocardial pathway protected from cryoablation by the warm, circulating blood pool. The closed-heart technique appears safe and efficacious. A potential limitation may be the presence of subendocardial AV pathways, which may require an alternative surgical approach at the site of the pathway to attain uniform primary success.

Adolescent↗
PubMed1985

Activation of the right ventricular apical electrogram during ventricular tachycardia: suitability for synchronizing intracavitary cardioversion.

An intravascular catheter positioned in the right ventricular apex has been used for intracavitary cardioversion in patients with recurrent ventricular tachycardia. We examined the timing of the right ventricular apical electrogram during sinus rhythm and ventricular tachycardia (VT) in order to determine if this signal could be used to synchronize the delivery of a countershock. Sixty-three distinct morphologies of VT were observed in 33 patients undergoing electrophysiologic testing with programmed stimulation. Regardless of VT morphology or site of origin, the bipolar right ventricular electrogram always occurred within the peripheral QRS complex during ventricular tachycardia. Relative timing occurred within the QRS ranging from the initial 13% of the QRS to the last 12%. When all episodes of VT were examined, the timing of the right ventricular electrogram did not correlate linearly with the peak of the ECG, but the right ventricular electrogram occurred within 60 ms of the peak ECG in 83% of episodes of ventricular tachycardia. In one case of arrhythmogenic right ventricular dysplasia, the right ventricular electrogram occurred 160 ms after the peak ECG in ventricular tachycardia, a time when delivery of a countershock may have precipitated ventricular fibrillation. Six of these patients underwent cardioversion utilizing an intracavitary catheter and external generator. Acceleration of VT, or conversion to ventricular fibrillation, occurred following two of 27 shocks (7.4%). The right ventricular electrogram occurred the latest within the QRS complex in the two patients who developed acceleration of the tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Bundle-Branch Block↗
PubMed1985

Nonclinical ventricular tachycardia in the Wolff-Parkinson-White syndrome.

Between September 1980 and June 1984 we assessed the specificity of induction of ventricular tachycardia (VT) with one or two ventricular extrastimuli in a consecutive series of 148 patients undergoing electrophysiological assessment for the Wolff-Parkinson-White (WPW) syndrome by standard electrophysiological techniques. Fifteen patients (10%) had six or more beats of VT induced by one ventricular extrastimulus after a ventricular drive (9 patients), two ventricular extrastimuli during reciprocating tachycardia (6 patients), and during a single atrial extrastimulus (1 patient). None of the six men and nine women, aged 16-61 years, had apparent heart disease. VT lasted for 20 +/- 14 (mean +/- standard deviation) cycles with a cycle length of 235 ms +/- 27 and was generally polymorphic. One patient had ventricular fibrillation. These patients were compared to 15 age- and sex-matched patients studied in the same time period. There was no difference in anterograde effective refractory period of the accessory pathway (316 +/- 92 vs 319 +/- 68 ms), ventricular effective refractory period (218 +/- 12 vs 227 +/- 23), shortest pacing cycle length maintaining 1:1 anterograde conduction over the accessory pathway (306 +/- 132 vs 320 +/- 67) or minimum R-R interval between preexcited beats during atrial fibrillation (280 +/- 68 vs 294 +/- 105). All patients are alive and well over a follow-up interval of 20 +/- 11 months on no antiarrhythmic therapy (13 patients) or on propranolol (2 patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗