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Biomedical subjects

J Vohra

Publications and source records attributed to J Vohra.

At least 37 records · Page 2Linked to original sources
PubMed1983

Electrophysiologic studies in survivors of late cardiac arrest after myocardial infarction.

Nine patients resuscitated from life-threatening ventricular arrhythmias (VA) within 3 months of an acute myocardial infarction (AMI) underwent electrophysiologic studies (EPS) with clinical follow-up for at least 12 months. Neither reinfarction, drug therapy, nor electrolyte imbalance was a precipitating factor. VA was induced by ventricular pacing in six of nine patients. Five patients were prescribed empiric drug therapy, while the four other patients had repeated EPS to select optimal drug therapy. One patient remained unstable and died of VA in the hospital. No patient was discharged and successfully maintained on a drug known to prevent induction of VA, yet only two patients (25%) had a further recurrence of VA, one fatal. Our findings suggested that either drug therapy that is determined empirically or found not to suppress the induction of VA during EPS can be associated with a successful outcome in some of these patients, or the natural history of VA after myocardial infarction is that they are self-limiting in the absence of a new ischemic event.

Arrhythmias, Cardiac↗
PubMed1983

Comparison of lead complications with polyurethane tined, silicone rubber tined, and wedge tip leads: clinical experience with 822 ventricular endocardial lads.

Lead-related complications have been prospectively studied for 602 unipolar tined endocardial ventricular pacemaker leads implanted over a five-year period. No differences were noted in overall complication rates between 238 polyurethane insulated leads (4.2%) and 364 silicone rubber insulated leads (3.6%). Comparing the total series of 602 tined leads to a retrospective survey of 220 wedge tip leads, a marked reduction in dislodgements (0.3% vs. 7.7%, P less than 0.001) and reoperations (2.0% vs 15.0%, P less than 0.001) was found using tined leads. We conclude that tined ventricular leads are far superior to wedge tip leads with respect to lead complications.

Arrhythmias, Cardiac↗
PubMed1982

Prediction of sudden death by electrophysiologic studies in high risk patients surviving acute myocardial infarction.

Seventy patients surviving a myocardial infarction complicated by heart failure or arrhythmias, or both, were studied 7 to 20 days after the infarction. Twenty-four hour electrocardiographic ambulatory monitoring and intracardiac electrophysiologic studies were performed in each patient. Electrophysiologic studies included introduction of single right ventricular premature stimuli during sinus rhythm (70 patients), atrial pacing (35 patients) and ventricular pacing (70 patients) at a stimulating voltage of 2 V, with the use of higher stimulating voltages (up to 10 V), and double right ventricular premature stimuli in 33 patients and pacing at a second right ventricular site in 50 patients. A repetitive response was defined as two or more spontaneous ventricular depolarizations in response to the premature stimuli, with His bundle reentry and aberrant conduction of supraventricular impulses excluded by a His bundle recording. Repetitive responses were initiated in 20 patients, and 12 patients had responses that were either sustained ventricular tachycardia or self-terminating ventricular tachycardia of more than five complexes in duration. The finding of a repetitive response was not related to the occurrence of complex ventricular arrhythmias during ambulatory monitoring or in the coronary care unit. Five of the 12 patients with sustained or self-terminating responses of more than five complexes died during the 12 month follow-up period, 4 suddenly, and these responses were significantly associated with late sudden death (p less than 0.05), because only 1 of 25 patients with responses of fewer than five complexes or no response to maximal provocation died suddenly. It is concluded that induced responses of more than five complexes in duration may be an important indicator of a potentially reversible risk of sudden death after myocardial infarction.

Adult↗
PubMed1982

Verapamil in cardiac arrhythmias: an overview.

1. Verapamil remains the most widely used calcium antagonist for the treatment of cardiac arrhythmias. It is the most potent and effective drug for the acute treatment of paroxysmal supraventricular tachycardia particularly, circus movement tachycardia with or without pre-excitation. 2. As it is a powerful depressant of atrioventricular nodal conduction it reduces the ventricular rate in atrial flutter and fibrillation with reversion to sinus rhythm in a proportion of patients with these arrhythmias. Because verapamil does not increase airways resistance it can be used in patients with obstructive airways disease. The drug is also effective in supraventricular tachyarrhythmias following open-heart surgery and myocardial infarction. 3. It is not an effective drug against ventricular arrhythmias unless due to coronary artery spasm. The use of verapamil should be avoided in the presence of sick sinus node syndrome, clinical cardiac failure and treatment with other negative inotropic drugs.

Administration, Oral↗
PubMed1981

Patient initiated implantable pacemakers for paroxysmal supraventricular tachycardia.

Seven patients with recurrent paroxysmal supraventricular tachycardia (PSVT) resistant to standard drug therapy were treated with patient initiated implantable pacemakers. All patients had required frequent hospital admissions and cardioversions prior to pacemaker implantation. Two patients had Wolff-Parkinson-White (WPW) syndrome on their surface ECGs and five patients had no ECG evidence of preexcitation. All patients had detailed electrophysiological studies. Three patients had junctional tachycardia, one patients had reciprocating atrial tachycardia and in three, including one with normal surface ECG, retrogradely conducting accessory atrio-ventricular connections (AAVC) formed a part of the tachycardia circuit. Initiation and termination of tachycardia were re-checked at subsequent studies. On the basis of these studies, two patients with WPW syndrome had right ventricular endocardial leads and custom-built, magnet actuated pacemakers capable of delivering right ventricular coupled stimuli at fixed, present intervals of 200 and 400 ms. Both these pacemakers provided inconsistent reversions and proved unsatisfactory. In the remaining five patients, a unipolar tined J-shaped right atrial (RA) lead (Medtronic 6991) and a radiofrequency (RF) receiver (Medtronic 5998T) were implanted and enabled patients to overdrive ranged from 14 to 20 months. Several episodes of PSVT have been consistently reverted and none have required hospitalisation or cardio-version. Two patients had transient atrial fibrillation following the application of RF pacemaker. Three have required no antiarrhythmic drugs and in two the drug therapy has been greatly reduced and simplified. The Medtronic 6991 lead provided satisfactory RA stimulation without dislodgement. In carefully selected patients with PSVT, RF pacemakers provide a useful mode of treatment.

Adult↗
PubMed1980

Effect of therapeutic dosage of lithium on the heart.

1 The cardiac effects of therapeutic levels of lithium were investigated in six healthy male volunteers. Subjects were studied: (1) before lithium ingestion, and (2) when steady-state plasma lithium levels were attained (at least 2 weeks after beginning daily lithium ingestion). 2 A 12-lead electrocardiogram (ECG) and high-speed high-fidelity ECG were used to record electrical activity of the heart. Fractional shortening of the left ventricle using echocardiography, and systolic time intervals (at rest and during exercise), were used as measures of myocardial performance. 3 In this group of healthy volunteers administration of lithium carbonate was associated with a reduction in T wave amplitude in standard electrocardiograms but no statistically significant impairment of myocardial performance.

Adolescent↗
PubMed1980

Plasma nomifensine concentration. Cardiological effects and clinical response.

Cardiological effects of nomifensine were studied in 10 endogenously depressed in-patients receiving up to 200 mg/day for 3 weeks. No significant cardiac effects were observed using His' bundle electrography and electrocardiography. 9 of the 10 patients showed a significant recovery from their depressive illness. Plasma nomifensine concentrations at day 22 were not correlated with clinical response, blood pressure, or electrocardiographic parameters. A negative correlation between A-H interval, in the His' bundle electrogram, and day 22 nomifensine concentration was observed.

Adolescent↗
PubMed1979

Effect of mianserin on cardiac conduction.

A cardiovascular study of a new antidepressant, mianserin, given at 60 mg a day for a three-week period to 10 ambulant, moderately depressed patients is described. No effects on cardiac conduction were found by means of His bundle electrocardiography. Nine of 10 depressed patients improved while on the medication; mild sedation was the only side effect noted.

Adult↗
PubMed1978

Cardiological effects of nomifensine, a new antidepressant.

A cardiovascular study of a new antidepressant, nomifensine, revealed no significant cardiac effects in eight ambulant patients who received up to 200 mg of nomifensine per day for three weeks. In an electro-physiological study of cardiac conduction, nomifensine had significantly less effect on cardiac activity than amitriptyline and doxepin. Results of the clinical and the experimental studies suggest that nomifensine may be of value in treating the depressed patient with heart disease.

Action Potentials↗
PubMed1978

Electrophysiology of disopyramide in man.

The electrophysiological effects of an intravenous dose of disopyramide phosphate (2 mg per kg body weight) were studied in 17 patients. Studies were performed with the patients fasting, unpremedicated, and off all medication for three days. Blood samples for estimation of serum levels of disopyramide were collected in 15 of these patients. The effects of intravenous disopyramide were maximal at five minutes, less marked at 20 minutes, and largely gone by 30 minutes after administration of the drug. Sinus cycle length and corrected sinus node recovery time were shortened significantly. No index of atrioventricular nodal function was significantly changed. Both atrial and ventricular effective refractory periods were significantly prolonged. Further impairment of intraventricular conduction occurred in six patients with bundle branch block on electrocardiogram or prolonged HV interval. In one of two patients with Wolff-Parkinson-White syndrome, the bypass effective refractory period was prolonged. These electrophysiological changes are similar to quinidine and quinidine like drugs. It is recommended that disopyramide should be used cautiously in patients with evidence of His Purkinje system disease since it may lead to higher degrees of intraventricular block.

Adolescent↗
PubMed1976

The effect of tricyclic antidepressant drugs on the heart.

The effects on the heart rate and ECG of anaesthetised guines-pigs of amitriptyline, doxepin, imipramine and nortiptyline infused at 1.0 mg/kg/min until death were observed. In addition an in vitro study on guinea-pig atria was performed on the chronotropic and inotropic effects of these drugs and of desmethylimipramine and protriptyline at a concentration of 10(-5) M. The effect of sodium bicarbonate (3 mEq/kg i.v.) and propranolol (0.01--0.2 mg/kg i.v.) on amitriptyline and doxepin induced ECG changes was also assessed. A difference in the cardiac effects of the in vivo and in vitro model was observed. Guinea-pigs infused with doxepin survived significantly longer than those infused with amitriptyline, imipramine or nortriptyline. No statistically significant difference was found between the tricyclic drugs with respect to onset of widening of the QRS complex, increased PR and QT intervals. In the spontaneously beating atrial preparation doxepin was the most potent cardio-depressant. Sodium bicarbonate had no effect on arrhythmias induced by tricyclics, while propranolol, apart from the bradycardia induced, was without beneficial effect on the ECG. The guinea-pig provides a good model for studying the arrhythmogenic actions of tricyclic antidepressants.

Animals↗
PubMed1976

Cardiac effects of different tricyclic antidepressant drugs.

The effects of tricyclic antidepressants on the heart are reviewed. Statistically significant increases in heart rate and in atrioventricular conduction times were found following the administration of tricyclic drugs to 32 depressed patients. The method of His bundle electrocardiography was used to study atrioventricular conduction in ambulant patients and in patients admitted after an overdose of tricyclic antidepressant drugs. Distal conduction defects were frequently found in patients following tricyclic overdosage, but these were not seen with doxepin overdosage. Impaired distal conduction was also found in occasional patients on therapeutic doses of tricyclic drugs. Some animal experiments giving similar results to the above clinical findings are also described. The clinical implications of these findings are discussed.

Amitriptyline↗
PubMed1975

Clinical experience with verapamil.

Verapamil administered by the intravenous route restored sinus rhythm in 33 out of 40 episodes of supraventricular tachycardia. The drug was also effective in reducing ventricular rate in patients with atrial fibrillation. Intracardiac conduction studies using His bundle electrograms showed prolongation of atrioventricular nodal conduction in eight out of nine cases after 5 mg of verapamil were given. The distal conduction was unaffected. Bradycardia and hypotension occurred in two cases and responded promptly to intravenous administration of atropine. Verapamil is an effective antiarrhythmic agent which is, in general, free from significant side effects.

Arrhythmias, Cardiac↗