Cardiopulmonary hemodynamics in systemic sclerosis and response to nifedipine and captopril
Article Abstract:
Systemic sclerosis (SSc), or scleroderma, is a chronic disease characterized by sclerosis, or hardening, of the skin and certain organs, including the gastrointestinal tract, lungs, heart, and kidneys. The skin becomes tight, firm, and edematous, or filled with tissue fluid. Lung complications of SSc are common and associated with a poor prognosis. The changes in the lung include fibrosis, or formation of fiber-like tissue, and development of pulmonary hypertension, or increased pressure in the circulation of the lungs. The degree of pulmonary fibrosis is not correlated with pulmonary blood vessel changes in SSc. Pulmonary vasospasm, or uncontrolled muscle contraction of the blood vessels in the lungs, may contribute to Raynaud's phenomenon of the lung. Raynaud's phenomenon is a vascular disorder characterized by abnormal blood vessel constriction, and usually involves blood vessels of the extremities. Pulmonary vasoconstriction may contribute to the development of lung disease processes, including pulmonary hypertension. Vasodilators, or agents that dilate blood vessels, may be effective in preventing pulmonary hypertension in patients with SSc. The effects of the vasodilators nifedipine and captopril on the circulation of the lungs were assessed in 20 patients with SSc, Raynaud's phenomenon, and normal heart function. The pulmonary circulation was normal in half of the patients (group A), whereas the remaining half (group B) had increased resistance to blood flow within the lungs. Four group B patients had pulmonary hypertension. Nifedipine and captopril were more effective in patients with excessive resistance to blood flow in the pulmonary vessels, whereas the disease duration was shorter in patients with normal circulation. Nifedipine caused significant decreases in pulmonary vascular resistance and pulmonary pressures in group B patients. These findings show that nifedipine is beneficial in treating pulmonary hypertension associated with SSc. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: American Journal of Medicine
Subject: Health care industry
ISSN: 0002-9343
Year: 1991
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Erythromycin-induced long QT syndrome: concordance with quinidine and underlying cellular electrophysiologic mechanism
Article Abstract:
Ventricular tachyarrhythmias are rapid heart rates arising in the heart ventricles and may be caused by various drugs. The long QT syndrome is a type of tachyarrhythmia, characterized by particular abnormalities in the electrical activity of the heart that can be observed on an electrocardiogram (ECG). These electrical abnormalities in the ECG include the prolongation of the QT-interval; an exaggerated U wave; and torsades de pointes, which are signals on the ECG reflecting ventricular tachycardia. Ventricular tachyarrhythmias usually resolve, but may result in syncope (fainting) or deteriorate to ventricular fibrillation, which is a potentially life-threatening abnormal heart rhythm. Within the last several years, the antibiotic erythromycin has been reported to cause long QT-syndrome. A case is described of a 76-year-old man who developed torsades de pointes as a result of treatment with the cardiovascular agent quinidine. The ventricular arrhythmias resolved after discontinuation of quinidine. However, after the patient was given the antibiotic erythromycin to treat pneumonia, the torsades de pointes recurred. The antibiotic was withdrawn and the ventricular arrhythmias resolved. These findings indicate that erythromycin can cause the long QT syndrome by direct effects on the heart's electrical activity. In addition, the sensitivity of the heart to these effects of erythromycin may be enhanced by class IA antiarrhythmic agents such as quinidine. Treatment with erythromycin should be avoided in patients with a history of long QT-syndrome, and patients with predisposing factors to long QT-syndrome should be closely monitored when being treated with intravenous erythromycin. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: American Journal of Medicine
Subject: Health care industry
ISSN: 0002-9343
Year: 1990
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