Search PubMed⌕ Search

Biomedical subjects

R A DeSilva

Publications and source records attributed to R A DeSilva.

26 records · Page 2Linked to original sources
PubMed1978

Roles of psychologic stress and autonomic nervous system changes in provocation of ventricular premature complexes.

Neural and psychologic factors have been implicated as risk factors for ventricular arrhythmias and sudden death in man. However, the relation between these factors and arrhythmia has hitherto not been systematically explored. We examined the effect of psychologic stress testing in 19 patients with advanced grades of ventricular arrhythmias. Psychologic stress consisted of mental arithmetic, reading from colored cards and recounting emotionally charged experiences. Such testing induced a significant increase in ventricular premature beat frequency in 11 of 19 patients (P less than 0.05). One patient experienced paroxysms of ventricular tachycardia. In 14 of these 19 patients elicitation of vagal or sympathetic autonomic reflexes failed to induce significant arrhythmia in all but one patient. It is concluded that (1) objective psychologic tests may precipitate ventricular arrhythmia in susceptible patients, and (2) evocation of peripheral autonomic reflexes is an insufficient trigger for enhanced ventricular ectopic activity.

Adolescent↗
PubMed1978

The effects of psychological stress and vagal stimulation with morphine on vulnerability to ventricular fibrillation (VF) in the conscious dog.

Ventricular vulnerability to fibrillation was assessed in 12 conscious dogs in aversive and nonaversive environments using the repetitive extrasystole (RE) threshold method. In the average environment, RE threshold was 45 per cent lower than in the nonaversive setting and heart rate and blood pressure were significantly elevated. This decrease in RE threshold occurred within 10 minutes of exposing the animals to stress. In contrast, the recovery in RE threshold in the nonaversive setting occurred over a 40 minute period. When morphine sulfate (MS) 0.25 mg./Kg was administered to dogs in the aversive environment, the RE threshold was significantly increased. Cholinergic blockade of vagal efferent activity with atropine (0.2 mg./Kg) annulled partially the effect of MS on RE threshold MS was without effect in the nonaversive environment. It is concluded that MS exerts a significant protective effect on increased ventricular vulnerability associated with psychological stress. This effect is mediated by the vagotonic and sedative actions of morphine.

Animals↗
PubMed1978

Energy requirement for defibrillation of a markedly overweight patient.

Recommendations have been made recently that the energy output of present-day defibrillators be increased above the 400 wsec limit. These recommendations are based largely on experimental studies in animals. We report a case of a man weighing 190.1 kg (418.2 lb), successfully resuscitated with a single 400 wsec shock after a prolonged episode of ventricular fibrillation. The observation in this patient as well as data derived from cardiovascular experience indicates that weight is not a significant factor in the successful outcome following defibrillation in adults. Many variables primarily related to the clinical condition of the heart influence the results of countershock. There are no valid studies at present to support the claim that high-energy defibrillators are necessary. In fact, implementation of such a recommendation is premature and possibly dangerous.

Adult↗
PubMed1977

Mitral valve prolapse with atrioventricular and sinoatrial node abnormalities of long duration.

A 20-hear-old patient with mitral valve prolapse and minimal mitral regurgitation associated with intermittent marked sinus bradycardia and sinus arrhythmia, and atrioventricular block, proximal to the bundle of His, varying from first-degree to high-grade, is described. Both the murmur and the atrioventricular block had been documented since the age of eight years, and probably since the first year of life, and has shown no subsequent progression. The patient's symptoms of chest pain and severe lightheadedness and near syncope have been shown by telemetry electrocardiogrphic monitoring to be unrelated to changes in cardiac rhythm.

Adult↗
PubMed1977

Mitral valve prolapse in rheumatic mitral stenosis.

Four adult women with histories of rheumatic fever and clinical findings of mitral stenosis and regurgitation had echocardiograms demonstrating moderately severe mitral stenosis (EF slope less than 20 mm/sec, mean left atrial size 3.0 cm/m2, mean anterior mitral leaflet excursion 25 mm) as well as typical mitral valve prolapse. Three patients underwent cardiac catheterization which confirmed the presence of mitral stenosis, as well as systolic prolapse and excessive scalloping of the mitral valve with no visible mitral calcium and no coronary artery disease. One patient had associated mild aortic stenosis and regurgitation. Two patients underwent mitral valve surgery which revealed anterior and posterior commissural fusion consistent with rheumatic disease and intact chordal apparatus. Both leaflets were large and the anterior leaflets were redundant. There were no vegetations. Pathology revealed myxomatous degeneration of the valve leaflets. In the absence of heavy calcification and thickening, the presence of mitral stenosis with commisural fusion does not exclude the possibility of a redundant mitral valve. When these entities coexist, systolic clicks may be absent.

Aged↗