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Biomedical subjects

J A Kastor

Publications and source records attributed to J A Kastor.

At least 19 recordsLinked to original sources
PubMed1988

Pacemaker mania.

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Arrhythmias, Cardiac↗
PubMed1983

Ventricular premature beats.

Ventricular premature beats (VPBs) are the most common cardiac arrhythmia. Simple VPBs have one form. Complex VPBs are repetitive, bigeminal, frequent, have different forms, or occur in the T wave of the previous beat. VPBs are seen frequently in patients with normal hearts, coronary artery disease, and mitral valve prolapse. In patients with normal hearts, VPBs are discovered with higher incidence when ambulatory or exercise electrocardiography is used to supplement the standard ECG. Patients with normal hearts and VPBs have a benign prognosis, and drug treatment is seldom needed. Most patients with stable angina pectoris and/or healed myocardial infarctions have VPBs on ambulatory and exercise electrocardiographic testing. These patients die sooner when VPBs are found than when none occur; complex VPBs suggest an even worse prognosis. Treatment of VPBs may relieve such symptoms as palpitations, but change in the prognosis by successful suppression has not yet been demonstrated. VPBs often occur during episodes of Prinzmetal's vasospastic angina. Treatment is directed principally toward relief and prevention of the spasm. All patients with acute myocardial infarction (AMI) have VPBs. Their incidence is highest at the onset of the illness. The number and complexity of the VPBs rise when myocardial damage is greater. VPBs should be prevented and, if present, vigorously suppressed to prevent ventricular fibrillation from developing during AMI. VPBs can be detected with exercise and ambulatory electrocardiography in most patients who have survived an acute episode of myocardial infarction. The prognosis is adversely affected by the presence of simple VPBs and even more ominous when complex VPBs are found. That the prognosis can be improved by suppression of VPBs after myocardial infarction has not been conclusively established. Survivors of cardiac arrest usually have simple and complex VPBs. The likelihood that further arrests will occur can be decreased by administration of antiarrhythmic drugs in sufficiently high doses to produce therapeutic blood levels or prevent induction of ventricular arrhythmias during electrophysiologic studies. A majority of patients with mitral valve prolapse have VPBs. Few require specific treatment for the arrhythmia.

Angina Pectoris↗
PubMed1982

Amiodarone for control of sustained ventricular tachyarrhythmia: clinical and electrophysiologic effects in 51 patients.

We evaluated the electrophysiologic effects of amiodarone and its ability to control ventricular arrhythmia in a selected group of 51 patients with refractory sustained ventricular arrhythmia. Amiodarone in doses of 400 to 800 mg/day prolonged refractoriness in the atria, atrioventricular (AV) node, and ventricle as well as conduction through the AV node and His-Purkinje system. Although it had no effect on measurements of sinus nodal function (sinus nodal recovery time and sinoatrial conduction time), it prolonged the sinus cycle length and 2 patients required a permanent pacemaker for symptomatic sinus bradycardia. Amiodarone did not alter the ease of inducibility in any consistent manner, and only 5 of 43 patients (12%) who had inducible ventricular tachycardia before amiodarone therapy had none induced during amiodarone treatment. The clinical effectiveness of amiodarone could be evaluated in 46 patients followed up for 8.6 +/- 6 months (range 0.5 to 22). It provided effective therapy in 23 patients (50%), partly effective therapy in 13 (28%), and was ineffective in 10 (22%). Adverse effects were noted in 28 of 51 patients (55%), and in 11 of these (22%) the drug had to be discontinued because of adverse effects. We conclude that amiodarone is a useful agent for the treatment of refractory sustained ventricular arrhythmia. Its use should be reserved for patients with life-threatening sustained arrhythmia because of the significant incidence of adverse effects. Furthermore, good clinical response can be observed in patients receiving amiodarone in spite of continued inducibility.

Adolescent↗
PubMed1981

Coronary-artery spasm immediately after myocardial revascularization: recognition and management.

We investigated coronary-artery spasm in six patents who had had unexpected hemodynamic collapse within two hours after cardiopulmonary bypass for myocardial revascularization. All six had profound hypotension and recurrent ST-segment elevation in electrocardiographic Leads II, III, and aVF. All had either normal or noncritical luminal irregularities of dominant right coronary arteries and more than 75 per cent occlusions in the left coronary circulation. Right-coronary-artery spasm, which was reversed after intracoronary nitroglycerin, was demonstrated angiographically in one patient; a patent right coronary artery was found at autopsy in another patient. Three patients died despite large intravenous doses of nitroglycerin. Two patients who had been unresponsive to intravenous nitroglycerin recovered after direct infusion of nitroglycerin into the right coronary artery. Coronary-artery spasm immediately after myocardial revascularization may cause circulatory collapse and death; although the spasm may be refractory to usual therapy, it may respond to intracoronary nitroglycerin.

Adult↗
PubMed1981

Surgical treatment of ventricular arrhythmias in coronary artery disease.

Serious ventricular arrhythmias, a common complication of coronary artery disease, frequently respond to medical management. When pharmacologic and pacemaker therapy fail to control them, however, surgical therapy must be considered. In this review we assess the efficacy of surgical treatment of these arrhythmias. Coronary revascularization fails to reduce the frequency and complexity of ventricular ectopic activity and may exacerbate them. Recurrent ventricular fibrillation due to acute, reversible ischemic events may respond favorably to coronary revascularization. Recurrent ventricular fibrillation associated with recent myocardial infarction when unresponsive to medical therapy can be managed with coronary revascularization and infarctectomy with comparatively good results. Recurrent sustained ventricular tachycardia is not optimally treated with coronary artery bypass grafting and myocardial resection. Operations guided by activation mapping that isolate or destroy the site of origin of the ventricular tachycardia show promise.

Arrhythmias, Cardiac↗