Biomedical subjects

R F Malacoff

Publications and source records attributed to R F Malacoff.

10 recordsLinked to original sources

PubMed1988

Total obstruction of the left main coronary artery.

A rare and often fatal condition, total obstruction of the left main coronary artery has been treated with increasing success in both acute and chronic clinical settings. Seventeen patients with acute occlusion have been reported in the literature. All were discovered at the time of acute periinfarction catheterization and were treated aggressively with intracoronary thrombolysis, percutaneous transluminal angioplasty, emergency bypass surgery, or a combination of techniques. Chronic total occlusion of the left main coronary artery has been reported in 59 patients, including 3 at our institution. These patients present with chronic but increasingly severe angina. A right dominant coronary anatomy is always found, usually with well-developed right-to-left collaterals. The results of surgical revascularization in our 3 patients and in 45 others described in the literature support the safety and efficacy of this approach.

Acute Disease↗

PubMed1986

Ventricular arrhythmia: management strategy.

The management of ventricular arrhythmia continues to be one of the most difficult therapeutic problems in medicine today. Both invasive and noninvasive techniques have demonstrated success in management of patients at high risk for sudden cardiac death. High-risk subgroups include patients who have experienced sudden cardiac death and have been resuscitated successfully, patients with high-grade ventricular ectopy associated with left ventricular dysfunction, and patients who have had recent myocardial infarction. Traditional and experimental antiarrhythmic agents are available to the clinician, and in some patients combination therapy may prove more useful than application of a single agent alone. In individuals in whom pharmacologic intervention fails, map-guided surgical excision may be beneficial. The application of the automatic implantable defibrillator appears to have promise in truly refractory situations.

Anti-Arrhythmia Agents↗

PubMed1985

Echocardiographic manifestations of tense pericardial effusion.

Echocardiography has emerged as a sensitive study in the evaluation of pericardial effusion. The specificity of echocardiographic signs in cardiac tamponade remains undefined, however. Two such signs, early diastolic collapse of the right ventricular free wall and late diastolic collapse of the right atrial wall, were observed in two patients without clinical evidence of cardiac tamponade. Increased intrapericardial pressure was documented in each patient. Accumulation of pericardial fluid under high pressure results in a reversal of the instantaneous transmural pressure gradients in early and late diastole, causing collapse of the right ventricular and the right atrial wall, respectively; however, such a tense pericardial effusion may not cause hemodynamic embarrassment severe enough to yield clinical signs of cardiac tamponade.

Adult↗

PubMed1984

Long-term clinical outcome of ventricular tachycardia or fibrillation treated with amiodarone.

The determinants of long-term clinical outcome were studied in 42 patients with recurrent ventricular tachycardia (VT) or ventricular fibrillation (VF) who were treated with amiodarone as the sole antiarrhythmic agent. Of the 42 patients, 11 (26%) either died suddenly or had recurrent, symptomatic, sustained VT during a mean follow-up period of 10 months (range 0.3 to 45). Of the 19 patients without inducible VT/VF during electrophysiologic study while receiving amiodarone, 1 patient died suddenly but no patient had recurrent VT/VF. Ten of the 23 patients (43%) with persistently inducible arrhythmia have died suddenly or have had recurrent VT/VF. Using survival and stepwise logistic regression analyses, 2 significant independent predictors of recurrent arrhythmia were identified; persistently inducible VT during electrophysiologic testing in patients receiving amiodarone therapy (p less than 0.002) and the left ventricular ejection fraction at rest (p less than 0.05). The predictive accuracy of the response to serial electrophysiologic testing during amiodarone therapy was 67%, the sensitivity was 58% and the specificity was 91%. Thus, serial electrophysiologic testing is useful for determining the prognosis in patients with inducible VT/VF treated with amiodarone.

Aged↗

PubMed1984

Sudden cardiac death. Helping those at risk survive.

Sudden cardiac death continues to pose a major public health problem in the United States. The underlying cause in the vast majority of patients is arteriosclerotic heart disease, and the pathophysiologic mechanisms are ventricular tachycardia and ventricular fibrillation. In patients identified to be at great risk for sudden cardiac death, both noninvasive and invasive techniques are available to help guide antiarrhythmic therapy. When arrhythmias occur frequently, noninvasive techniques may be adequate to allow sequential pharmacologic testing until an effective regimen can be defined. However, in patients whose frequency of arrhythmia at rest is low, provocative techniques are required. In patients for whom a successful pharmacologic regimen is defined, the outlook is good and the chance of sudden cardiac death is considerably decreased.

Anti-Arrhythmia Agents↗

PubMed1983

Effect of the cold pressor test on regional myocardial blood flow in patients with coronary artery disease.

The cold pressor test is a potent alpha-adrenergic vasoconstrictor stimulus, but its effect on regional myocardial blood flow in patients with coronary artery disease is unknown. In this study, 17 patients with chest pain syndromes who were receiving beta-adrenergic-blocking drugs underwent regional myocardial blood flow determination by the xenon-133 technique before and after the cold pressor test. Nineteen of 28 regions analyzed were distal to significant coronary artery lesions (greater than 70% reduction of luminal diameter), while the remainder were in patients with normal coronary arteries. Patients with normal and stenotic coronary arteries had a similar increase in heart rate-pressure product, but in patients with normal coronary arteries, regional myocardial blood flow increased in nine of nine regions (average increase 11.6 +/- 1.3%, p less than 0.01) while either decreasing or remaining unchanged in 14 of 19 regions distal to coronary artery lesions (average decrease 13.6 +/- 1.6%, p less than 0.05). This difference between groups was significant (p less than 0.01), demonstrating an inappropriate reduction of regional myocardial blood flow and suggesting that alpha-adrenergic vasoconstriction may contribute to myocardial ischemia.

Adrenergic beta-Antagonists↗

PubMed1982

Beneficial effects of nifedipine on regional myocardial blood flow in patients with coronary artery disease.

Nifedipine inhibits the slow-channel calcium current, which plays a major role in vascular smooth-muscle contraction. However, the effect of nifedipine on regional myocardial blood flow (RMBF) in patients with coronary artery disease (CAD) is unknown. In 18 patients with chest pain syndromes, RMBF was determined with xenon-133 before and after nifedipine. In patients with CAD. 25 regions were analyzed distal to significant coronary obstruction(greater than 70% reduction in luminal diameter) and eight regions were analyzed in patients with normal coronary arteries. In patients with CAD, RMBF increased in 21 of 25 regions (average 17.4 /+- 5.7%,p less than 0.01), but decreased in all eight regions in patients with normal coronary arteries, by an average of 14.4 /+- 2.3% (p less than 0.01). The difference between groups was significant (p less than 0.01). In our patients with CAD, improved RMBF appears to be related to a decrease in coronary vascular tone and suggests a physiologic basis for the beneficial effect of nifedipine in ischemic heart disease.

Adult↗

PubMed1980

Oral amrinone in refractory congestive heart failure.

The acute effects of an oral preparation of amrinone, a recently synthesized cardiotonic agent, were assessed noninvasively in nine patients who had advanced heart failure that persisted despite treatment with digitalis, diuretic drugs and afterload-reducing agents. All patients demonstrated an improvement in left ventricular ejection fraction determined by radionuclide ventriculography (20.3 +/- 2.8 to 30.8 +/- 4.8 percent [mean +/- standard error of the mean], p less than 0.005) after a single dose of amrinone. Initial effects were seen within 1 hour, with the peak effect occurring at 1 to 3 hours; persistent effects were demonstrable at 4 to 6 hours. No change in blood pressure, heart rate or rhythm was observed, and there was no clinical evidence of myocardial ischemia. Continued benefit was demonstrated by radionuclide ventriculography in two patients treated for 1 and 6 weeks, respectively, although two other patients experienced major side effects with the chronic administration of amrinone. Although orally administered amrinone shows promise as a potentially useful agent in the treatment of advanced heart failure, the safety of this drug remains to be established.

Aged↗

PubMed1979

Streptococcal endocarditis (nonenterococcal, non-group A): single vs combination therapy.

A 14-year experience with streptococcal endocarditis was reviewed. The effect of single vs combination antibiotic therapy on the relapse rate was found to be comparable. Of 68 patients treated, four patients died during therapy. Two of 46 patients receiving single-agent and none of 18 patients receiving combination therapy experienced a relapse. Duration of symptoms before diagnosis was the main risk factor predisposing to relapse, which occurred in two of 13 patients with symptoms for longer than three months and in none of 51 patients with symptoms for three months or less before diagnosis. Combination therapy offered no advantage over a single agent in the latter group. Optimal therapy for patients with symptoms for longer than three months could not be determined in this study. However, no relapses were observed in this high-risk group when a single agent was given for longer than 21 days.

Adult↗

PubMed1975

Effect of peritoneal dialysis on serum levels of tobramycin and clindamycin.

The pharmacokinetics of tobramycin and clindamycin were examined in patients undergoing peritoneal dialysis for chronic renal failure. Peak serum levels of tobramycin in functionally anephric patients were less than expected, probably secondary to a larger volume of distribution. Peritoneal dialysis resulted in a significant clearance of tobramycin, with a resultant reduction in serum half-life. The present data suggest that, if bactericidal serum levels of tobramycin are to be maintained in patients undergoing peritoneal dialysis, a parenteral loading dose be administered, followed by either (i) an identical dose every third half-life or (ii) one-half the loading dose every half-life. However, optimal therapy is best achieved by monitoring serum levels to insure appropriate drug dosage. Peak serum levels of clindamycin in functionally anephric patients were approximately twofold greater than those expected in normals after an identical parenteral dose. It is, therefore, recommended that the administered dose of this agent in functionally anephric patients be one-half of that required to produce desired peak serum levels in patients without renal impairment. Peritoneal clearance of clindamycin during dialysis was shown to be essentially zero, indicating that dialysis does not affect clindamycin disposition.

Anti-Bacterial Agents↗