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Biomedical subjects

J J Heger

Publications and source records attributed to J J Heger.

At least 37 records · Page 2Linked to original sources
PubMed1986

Survivors of cardiac arrest: prevention of recurrence by drug therapy as predicted by electrophysiologic testing or electrocardiographic monitoring.

Sixty-two patients (44 men and 18 women, aged 15 to 75 years) resuscitated from at least 1 cardiac arrest unrelated to acute myocardial infarction were studied. No patient was taking antiarrhythmic drugs at the time of the initial cardiac arrest. Thirty-five patients had coronary artery disease (CAD) and 27 did not. Before drug therapy, control electrophysiologic studies induced ventricular tachycardia (VT) in 43 of 58 patients (74%) (30 of 35 with CAD and 17 of 27 without CAD). At control continuous electrocardiographic monitoring for 48 hours or longer, only 19 of 62 patients (31%) had spontaneous VT, 5 of whom had no VT induced at control electrophysiologic study. Mean follow-up was 22 months. Fourteen of 41 patients, 8 of 25 with and 6 of 16 without CAD, had VT suppressed with drugs during serial electrophysiologic testing, and none had a recurrent arrhythmic event. VT was suppressed in 12 of 14 patients receiving conventional drugs. Of 27 patients with VT induced during all drug studies, 6 died from cardiac arrest and 4 had recurrent VT. Drug efficacy in 20 patients was guided by continuous electrocardiographic monitoring, and 4 of 9 patients in whom VT and ventricular pairs were suppressed by drug therapy, as documented by continuous electrocardiographic monitoring for 48 hours or longer, died of cardiac arrest. Overall, 26 patients were discharged receiving amiodarone therapy, and 5 died of cardiac arrest and 3 had recurrent sustained VT.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

The implantable transvenous cardioverter: long-term efficacy and reproducible induction of ventricular tachycardia.

We followed 11 patients for 5 to 27 months (mean 14.9) after implantation of a permanent transvenous low-energy synchronized cardioverter to evaluate both long-term reproducibility of ventricular tachycardia (VT) induction via noninvasive programmed electrical stimulation with the cardioverter and efficacy of cardioversion. Induction and termination of VT were attempted at implantation and approximately every 3 months thereafter. All patients had coronary artery disease and were receiving antiarrhythmic drug therapy (amiodarone in eight). VT cycle length, morphology, and mode of induction were reproducible on multiple occasions in nine patients; clinical VT was induced inconsistently in two patients. Multiple VT episodes in five patients had one morphology, whereas two morphologies occurred in six patients. Synchronization of the shock within the QRS complex and right ventricular effective refractory periods determined via the cardioverter remained constant over the follow-up period. VT was terminated on every occasion in nine patients and on eight of nine occasions in one patient. Tachycardia was accelerated on three of five occasions in one patient. Consistently effective cardioversion energy (0.2 to 2.0 J) increased modestly in four patients. We conclude that patients with inducible monomorphic VT usually have sustained VT with similar characteristics inducible over a period of time and cardioversion and sensing functions of the cardioverter remain relatively stable over time.

Aged↗
PubMed1985

Electrophysiologic effects and clinical efficacy of oral propafenone therapy in patients with ventricular tachycardia.

The effects of the antiarrhythmic agent propafenone were evaluated in 25 patients with recurrent symptomatic ventricular tachycardia. Oral propafenone was given to a maximal dose of 300 mg every 8 hours. Ten of the 25 patients developed side effects or had inadequate suppression of spontaneous ventricular arrhythmias during propafenone therapy. Electrophysiologic studies were performed before and during drug therapy on the 15 patients who had a satisfactory clinical response. Propafenone increased the PR interval from 168 +/- 46 to 188 +/- 25 ms (p less than 0.007), the HV interval from 47 +/- 10 to 65 +/- 13 ms (p less than 0.005), the shortest atrial pacing cycle length to maintain 1:1 atrioventricular (AV) nodal conduction from 385 +/- 44 to 436 +/- 42 ms (p less than 0.005), the ventricular effective refractory period from 231 +/- 17 to 255 +/- 19 ms (p less than 0.001) and the ventricular functional refractory period from 260 +/- 15 to 278 +/- 17 ms (p less than 0.002). Before propafenone therapy, all 15 patients had ventricular tachycardia induced by programmed ventricular stimulation. During propafenone treatment, 12 patients still had ventricular tachycardia induced, and the tachycardia cycle length significantly increased from 236 +/- 44 to 374 +/- 103 ms (p less than 0.001). Ten patients were considered to have satisfactory electrophysiologic response to propafenone on the basis of either the inability to initiate ventricular tachycardia or a marked increase in ventricular tachycardia cycle length associated with lack of symptoms during the induced tachycardia. These patients were discharged receiving propafenone.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1985

Amiodarone: risk factors for recurrence of symptomatic ventricular tachycardia identified at electrophysiologic study.

Ventricular tachycardia induced by programmed electrical stimulation during amiodarone therapy often does not preclude a good clinical response. The purpose of this study was to determine whether use of discriminant analysis could distinguish patients who remained asymptomatic from those who subsequently developed symptomatic ventricular tachycardia or cardiac arrest. Studies were performed in 37 patients with sustained ventricular tachycardia who still had ventricular tachycardia induced during programmed electrical stimulation during amiodarone therapy. The mean follow-up time was 14.1 +/- 1.3 months (+/- SEM). Twenty-three patients remained asymptomatic, whereas 14 patients had symptomatic recurrence of their ventricular tachycardia. In patients with recurrence of arrhythmia compared with asymptomatic patients, administration of amiodarone caused a longer ventricular effective refractory period (296 +/- 8 versus 271 +/- 7 ms, p less than 0.05) and a greater change in corrected QT [QTc] interval (90 +/- 18 versus 44 +/- 9 ms, p less than 0.02), but no difference in the decrease in premature ventricular complexes after treatment with amiodarone. During amiodarone therapy, nonbundle branch reentrant repetitive ventricular responses were induced by a single ventricular extrastimulus during sinus rhythm in 9 of 14 patients with recurrent arrhythmias compared with 2 of 21 asymptomatic patients (p = 0.001). Also, less aggressive pacing techniques were required to induce ventricular tachycardia in 9 of 14 symptomatic patients compared with 4 of 23 asymptomatic patients (p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Amiodarone↗
PubMed1985

Amiodarone treatment in patients with ventricular arrhythmias.

Amiodarone has been used in the therapy of supraventricular and ventricular tachycardia, and has often been categorised as a class III rather than a class I agent. However, in patients with ventricular arrhythmias, amiodarone 800mg daily for 14 days prolonged the right ventricular effective refractory period by a mean of 18.8 msec (p less than 0.05), and HV interval by a mean of 5.2 msec (p less than 0.05), these changes being similar to those noted with drugs such as quinidine, procainamide, disopyramide and encainide. The antiarrhythmic efficacy of amiodarone was evaluated in 196 patients with recurrent sustained ventricular tachycardia, recurrent ventricular fibrillation or recurrent nonsustained ventricular tachycardia. Coronary artery disease, dilated (congestive) cardiomyopathy, or other forms of heart disease were present in most patients. After 1 month of therapy, 177 patients continued to receive amiodarone and, during the remainder of the follow-up period, 139 patients had no recurrence of spontaneous ventricular tachycardia or ventricular fibrillation. Sudden cardiac death occurred in 15 patients after a mean treatment period of 10.4 months. Overall, amiodarone was an effective form of therapy in patients with ventricular tachycardia and ventricular fibrillation.

Adolescent↗
PubMed1984

Antiarrhythmic and electrophysiologic effects of oral propafenone.

Twenty-six patients had ventricular tachycardia initiated at control electrophysiologic study and had a repeat study during oral propafenone therapy. Ten patients had had sustained ventricular tachycardia, 6 cardiac arrest and 10 symptomatic, nonsustained ventricular tachycardia. Twenty-two patients had heart disease, 18 of whom had coronary artery disease. During propafenone therapy, ventricular tachycardia could not be initiated during programmed ventricular stimulation in 5 patients, and in 21 patients the cycle length of induced ventricular tachycardia increased from 246 +/- 42 ms at control to 355 +/- 96 ms (p less than 0.001). Seventeen patients were discharged with propafenone therapy and have been followed for a mean of 11 months. No symptomatic ventricular tachycardia recurred in the 5 patients without inducible ventricular tachycardia during drug treatment. Six of 12 patients with inducible ventricular tachycardia during the drug study have remained asymptomatic. In conclusion, propafenone substantially prolongs the cycle length of ventricular tachycardia, and initiation of ventricular tachycardia by programmed ventricular stimulation at drug study does not preclude a favorable clinical outcome.

Adult↗
PubMed1984

Propafenone treatment of recurrent ventricular tachycardia: comparison of continuous electrocardiographic recording and electrophysiologic study in predicting drug efficacy.

Propafenone was administered to 29 patients who had multiple episodes of recurrent ventricular tachycardia (VT) or ventricular fibrillation (VF) despite previous antiarrhythmic therapy. All patients had 24-hour continuous electrocardiographic recording and electrophysiologic study in a drug-free control state and while receiving maximum doses of propafenone. During propafenone treatment, the mean frequency of ventricular premature complexes (VPCs) decreased 74% (p less than 0.05). There was more than an 83% decrease in VPC frequency in 17 of 29 patients, and 11 patients had 99 to 100% decreases. Propafenone prevented VT induction at electrophysiologic study in 6 patients, whereas another 12 patients were judged to have satisfactory electrophysiologic responses on the basis of slower VT rates and absence of hemodynamic compromise during VT. After long-term treatment from 2 to 26 months, 9 patients continued propafenone without evidence of recurrent arrhythmia. Six of these 9 patients had not VT induction at electrophysiologic study while receiving propafenone. The decrease in VPC frequency produced by propafenone was a poor predictor of a successful electrophysiologic study and of long-term therapy. In conclusion, propafenone has potential as an effective antiarrhythmic agent, but better methods to stratify risk for recurrence of VT and VF are needed.

Adult↗
PubMed1984

Development of the implantable transvenous cardioverter.

The development of the transvenous cardioverter, from the initial animal studies, to the clinical studies using temporary leads, to the initial permanent implants is described. Shocks less than or equal to 2.0 joules synchronized to the QRS complex and delivered through a specially designed catheter electrode placed in the apex of the right ventricle successfully terminate most episodes of ventricular tachycardia in patients. The implanted unit which also serves as a demand ventricular pacemaker, can be used to perform programmed electrophysiologic studies. Future devices must be capable of defibrillation and more accurate arrhythmia detection.

Aged↗
PubMed1984

Early experience with an implantable cardioverter.

We tested the efficacy and safety of a fully programmable cardioverter weighing 95 g, in terminating sustained ventricular tachycardia. The device was implanted tranvenously under local anesthesia in seven patients. On command from a programmer or automatically, the cardioverter delivered shocks through a lead inserted to the apex of the right ventricle. It also served as a demand ventricular pacemaker and could perform programmed ventricular stimulation or overdrive pacing. Cardioversion of ventricular tachycardia required less than 0.5 J (mean) and was well tolerated by the patients, who were awake and not sedated. In one patient, a shock terminated ventricular tachycardia with the device in the automatic mode but produced atrial fibrillation with a rapid ventricular response that was intermittently recognized as ventricular tachycardia, triggering additional shocks. One such shock in the ST segment produced ventricular fibrillation that was terminated transthoracically in the emergency room, without residual impairment. We conclude from these preliminary observations that cardioversion of sustained ventricular tachycardia by means of an implantable catheter device is feasible, but for the present its use in the automatic mode must be cautious and selective. The unit's small size, ease of implantation, usefulness for noninvasive electrophysiologic studies, programmability, and bradycardia pacing functions are advantages. The next-generation device must be able to defibrillate and provide better differentiation of arrhythmias.

Adult↗
PubMed1984

Functional bundle branch block: discordant response of right and left bundle branches to changes in heart rate.

Faster heart rates shorten refractoriness more in some tissues than in others. This study investigates whether faster heart rates shorten relative refractoriness more in the right than left bundle branch in humans. Premature atrial stimulation at 2 or more basic cycle lengths was performed in 314 patients with no evidence of atrioventricular conduction system disease. In 10 patients, both functional right and left bundle branch block (BBB) developed with premature atrial stimulation. Functional right BBB occurred at the longer basic cycle length, and functional left BBB at the shorter cycle length in 8 patients. In 2 patients functional right and functional left BBB were present at the same cycle length, but functional left BBB occurred at a shorter premature atrial coupling interval. For all patients, the mean functional right bundle branch relative refractoriness was 438 ms at a basic cycle length of 847 ms, and functional left bundle branch relative refractoriness was 357 ms at a cycle length of 622 ms (p less than 0.01). The HV interval was 45 +/- 15 ms at control and increased with functional left BBB to 77 +/- 19 ms (p less than 0.01), but not with functional right BBB. Thus, relative refractoriness of the right and left bundle branches are rate-dependent and discordant. At longer cycle lengths, relative refractoriness of the right bundle branch is greater than that of the left bundle branch, and at shorter cycle lengths relative refractoriness of the left bundle branch is greater than that of the right bundle branch. The relative refractory period curves "cross over" and can explain the presence of both functional right and left BBB in the same patient.

Adolescent↗
PubMed1984

Plasma and red blood cell concentrations of amiodarone during chronic therapy.

Amiodarone and a metabolite, desethylamiodarone, were measured in plasma of 55 patients and in both plasma and red blood cell (RBC) in 28 patients who received chronic amiodarone treatment. The assay for amiodarone and desethylamiodarone was performed by high-pressure liquid chromatography. During chronic treatment, median plasma concentration of amiodarone was 2.80 micrograms/ml and desethylamiodarone was 2.20 micrograms/ml. In matched samples, plasma amiodarone concentration exceeded RBC amiodarone concentration (p less than 0.001) and the RBC-to-plasma concentration ratio averaged 0.31. The plasma desethylamiodarone concentration was not significantly different from its RBC concentration, and the RBC-to-plasma concentration ratio averaged 1.29. There was a linear correlation between plasma concentrations of amiodarone and desethylamiodarone (r = 0.82) and between RBC concentrations of drug and metabolite (r = 0.71). Drug or metabolite concentrations in plasma and RBCs correlated directly with daily dosage of amiodarone. Adverse side effects during chronic amiodarone therapy were related most strongly to RBC drug and metabolite concentrations. The group with adverse side effects had a significantly higher RBC concentration of amiodarone, 150 vs 0.75 micrograms/ml (p less than 0.001), than did patients free of adverse effects. After dosage reduction, side effects abated and plasma and RBC concentrations of drug and metabolite decreased. These data indicate that there is an expected range of amiodarone and desethylamiodarone concentrations during chronic treatment and that adverse side effects correlate best with RBC concentrations of drug and metabolite. Red cell concentrations may reflect the amount of unbound, free amiodarone and desethylamiodarone in plasma.

Amiodarone↗
PubMed1984

Prolongation of the QT interval induced by probucol: demonstration of a method for determining QT interval change induced by a drug.

Sudden death has occurred in monkeys fed large doses of probucol, a cholesterol-lowering drug, given in combination with an atherogenic diet. These monkeys develop prolonged QT intervals and high serum levels of probucol. We investigated the effect of probucol on QT interval and the incidence of ventricular ectopy during a double-blind placebo-controlled study in 16 patients with less than 600 premature ventricular complexes (PVCs) per day and a corrected QT interval of less than 0.44 second. Seven patients received probucol and nine patients received placebo. Three 24-hour continuous ECG recordings were obtained prior to entry into the study and three additional recordings were obtained after 6 months of drug or placebo therapy. A 15-second ECG tracing was sampled from the continuous ECG recording every 30 minutes and, for the group, 15,000 QT intervals were measured permitting construction of QT versus R-R regression lines for each patient before and during therapy. Comparison of the regression lines revealed that the measured QT interval prolonged 20 +/- 18 msec during the awake state and 24 +/- 20 msec during sleep (mean + standard deviation) at matched heart rates in the seven patients receiving probucol (p less than 0.01). Using Bazett's formula to correct for rate, corrected QT interval prolonged 22 +/- 23 msec in the awake state and 20 +/- 18 msec in the asleep state (p less than 0.01). In probucol treated patients QT interval prolongation was directly related to increasing probucol plasma levels (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Evaluation of the patient with wide QRS tachycardia.

Acute and long-term therapy as well as prognosis in patients with wide QRS tachycardia differ depending on the mechanism of the arrhythmia. Twelve-lead electrocardiography and prolonged electrocardiographic monitoring are often diagnostic. However, additional techniques such as esophageal and right atrial electrocardiography, or His bundle electrocardiography with detailed electrophysiologic studies, are sometimes necessary to delineate the mechanism of the arrhythmia.

Adult↗
PubMed1984

Clinical use and pharmacology of amiodarone.

Amiodarone, an investigational drug in the United States, has had considerable use in this country and worldwide in the treatment of cardiac arrhythmias. This article reviews the clinical pharmacology of this potentially useful antiarrhythmic agent.

Amiodarone↗