International journal of cardiology
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Comparative Study
Tachycardia induced cardiomyopathy in dogs; relation between chronic supraventricular and chronic ventricular tachycardia.
Long-standing ventricular tachycardia (VT) and supraventricular tachycardia (SVT) can produce a reversible left ventricular dysfunction. The onset of cardiomyopathy and the severity of posttachycardic changes depend at least on three parameters of tachycardia, including its type (VT or SVT), rate and duration. Ten dogs (beagles) were paced at 180 beats/min for 3 weeks. ⋯ Left ventricular pulmonary capillary wedge pressure increased significantly after either type of tachycardia as compared with baseline values (SVT: 7.5 +/- 1.2 mmHg, VT: 8.4 +/- 1.1 mmHg vs. 1.9 +/- 1.5 mmHg, P < 0.05); the difference between tachycardias was not significant. The present study demonstrates that chronic SVT and VT result in left ventricular dysfunction in a relatively short time, even if the heart rate is not very high. Deterioration of left ventricular ejection fraction and dilation of the left ventricle are more marked in chronic VT than in chronic SVT.
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The prevalence of myocardial damage after coronary artery bypass grafting is related to the criteria of its evaluation. Indium-111 monoclonal antimyosin antibody scintigraphy has been shown to be highly sensitive and specific for even small areas of myocardial necrosis or injury like those of myocarditis or transplant rejection. Our purpose was to evaluate, by using this method, myocardial damage after uncomplicated coronary artery bypass grafting. ⋯ Indium-111 antimyosin uptake was clear in a group of patients after uncomplicated coronary artery bypass grafting. No correlation was observed between indium-111 antimyosin uptake or heart to lung ratio and creatine kinase, creatine kinase isoenzyme MB, glutamic oxalacetic transferase levels, duration of cardiopulmonary bypass or aortic cross-clamp time, while elevated serum beta myosin heavy chain fragments (IRMA Pasteur) were observed (1378 +/- 238 microU/l). This study suggests that some degree of myocardial damage, though silent, is common after coronary artery bypass grafting.
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Clinical Trial Controlled Clinical Trial
The incidence of asymptomatic paroxysmal atrial fibrillation in patients treated with propranolol or propafenone.
Anti-arrhythmic therapy for paroxysmal atrial fibrillation leads to complete symptomatic relief in a number of patients. The elimination of symptoms may be associated either with a complete elimination of arrhythmia or with a conversion of symptomatic atrial fibrillation into asymptomatic episodes of arrhythmia. The aim of the study was to evaluate the occurrence of asymptomatic paroxysmal atrial fibrillation in 52 patients treated with propafenone (35 drug trials) or propranolol (34 drug trials) by means of ambulatory ECG Holter monitoring. ⋯ S.) or by a significant slowing of ventricular response during atrial fibrillation in 4 patients (from 125 +/- 27 to 84 +/- 8 beats/min, P = 0.05). In conclusion, in a significant proportion of patients with symptomatic paroxysmal atrial fibrillation asymptomatic episodes of arrhythmia may occur while on anti-arrhythmic drug therapy. Some of these patients, particularly those with other risk factors for stroke such as advanced age or the presence of organic heart disease, may require anti-coagulant therapy or change in anti-arrhythmic treatment, and can be selected on the basis of ambulatory ECG monitoring.
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The clinical presentation of cardiac tamponade may uncover underlying pericardial disease. We describe a patient who was being treated for lone atrial fibrillation. In this case, direct current cardioversion for recurrence of atrial fibrillation was complicated by a life-threatening hemopericardium. A history of asbestos exposure was subsequently related to the subclinical pericarditis.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparative study of efficacy and safety of low-dose diltiazem or betaxolol in combination with digoxin to control ventricular rate in chronic atrial fibrillation: randomized crossover study.
The combination therapy of low-dose diltiazem or bexatolol with digoxin can be a useful adjunct for achieving heart rate control with minimal side effects. But there has not been a study including patients with impaired left ventricular function and evaluating whether the beneficial effects of medication will be maintained during a follow-up period. ⋯ Our study suggested that (1) combination therapy of low-dose betaxolol with digoxin was more superior to low-dose diltiazem with digoxin in controlling ventricular rate and reducing rate-pressure products; (2) the effects controlling ventricular rate, reducing rate-pressure products and improving exercise capacity have been well maintained even after 7 months of medication with each combination therapy.