Echocardiography and prosthetic valve malfunction.
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Biomedical subjects
Publications and source records attributed to V S Mathur.
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To aid in the study of coronary artery disease, 57 patients with complete left bundle branch block underwent clinical evaluation, treadmill exercise testing and cardiac catheterization. The patients were classified into two groups according to coronary angiographic findings: 30 patients with significant stenosis (70 percent or greater luminal narrowing) of at least one major vessel and 27 with no significant coronary artery disease. There was no difference in age, presenting symptoms or previous medical treatment between the two groups. There were more men in the group with coronary artery disease. Exercise-induced S-T changes were similar in the two groups; the sensitivity and specificity of these changes for the diagnosis of coronary artery disease were unacceptable irrespective of the criterion chosen. With additional S-T depression of either 1 or 2 mm below the baseline value, the predictive accuracy was only 53 percent. Combined exertional chest pain and 1 mm S-T depression increased the predictive accuracy of exercise testing to 71 percent. These data indicate that exercise-induced electrocardiographic changes do not facilitate detection of coronary artery disease in patients with complete left bundle branch block.
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A patient with tetralogy of Fallot who underwent a successful Blalock shunt procedure as a child was evaluated 28 years later because of clinical deterioration. Results of cardiac catheterization and angiography disclosed, in addition to a functioning shunt, evidence of an infundibular, subvalvular tumor and a large anastomosis between the left circumflex coronary artery and the bronchial arteries of the right lung with the possibility of "coronary steal". At operation, the Blalock and coronary-to-bronchial artery anastomoses were ligated; and total correction was performed including resection of the pulmonary valve and infundibulum, excision of the tumor, closure of the ventricular septal defect, and application of an outflow patch to enlarge the pulmonary annulus. The patient was discharged nine days after surgical correction.
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Two hundred consecutive patients with a history of chest pain undergoing cardiac catheterization, coronary angiography and atrial pacing have been analyzed to assess the clinical significance of Mobitz I atrioventricular (A-V) block developing with the stress of atrial pacing. Of 160 patients with coronary artery disease, 26 (16%) developed Mobitz I A-V block at rates below 140 beats/min. Eighteen of these 26 patients (69%) had electrocardiographic evidence of old inferior wall myocardial infarction, compared to only 34 of the remaining 134 patients (29%) (P = less than 0.01). During the mean follow-up of 29.5 months (range 18-50 months) none of the 26 patients has developed spontaneous second or third degree A-V block. Twenty-three of the 26 patients had an exercise test within one week of the pacing study. No A-V block was noticed during or immediately following exercise, although the mean heart rate attained during exercise was higher than the mean pacing rate at which the A-V block occurred (136 +/- 5 vs 122 +/- 3, P = less than 0.01). Eighteen of these 23 achieved heart rates equal to or higher than the pacing rate at which A-V block developed. Nineteen (83%) shortened their P-R interval during exercise and 4 (17%) did not change the P-R length. Although atrial pacing-induced Mobitz I A-V block may indicate a latent A-V nodal conduction abnormality in some cases, its demonstration does not necessarily predict the occurrence of spontaneous advanced A-V block. Exercise should not be restricted in these patients on the basis of such a finding during a pacing study.
Plasma half-life and metabolic clearance rate of antipyrine administered intravenously in a dose of 16 mg/kg body weight was studied in 10 children suffering from protein calorie malnutrition and five normal children matched in age and sex. Plasma half-life was increased and metabolic clearance rate was decreased in malnourished children (10.4 hr and 47.1 ml/hr per kg, respectively) in comparison to controls (6.3 hr and 70.1 ml/hr per kg, respectively). This observation indirectly reflects the lowered activity of microsomal oxidative enzyme of liver. Five children were restudied after nutritional rehabilitation of 17 to 25 days. Antipyrine plasma half-life decreased to 6.6 hr and metabolic clearance rate increased to 66.5 ml/hr per kg. These values were similar to those in normal children indicating biological recovery. The drug therapy in children with protein calorie malnutrition requires reconsideration in light of these observations.
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A prospective randomized study to evaluate aortocoronary bypass was done on 116 patients (56 surgical, 60 medical) who had documented coronary artery disease (70% luminal obstruction in a major artery). The two groups were similar in age and risk factors. All patients have been followed for a mean of 34 months, and recatheterization has been done in 106 of the survivors. Important results show that although most patients in both groups are improved, more surgical patients are asymptomatic (68 vs 8%). Exercise tolerance was better in the surgical group (+94% vs +43%). There was significantly greater evidence of preinfarction angina in the medical group (p less than 0.02), but survival was similar.
To evaluate the role of coronary bypass treatment of stable angina, 72 patients were randomly divided into surgical and medical groups. They were followed with treadmill tests and repeat catheterization. Anginal symptoms decreased or disappeared in 89 per cent of those operated on and 65 per cent of those not operated on, but more of the former than of the latter became asymptomatic: 69 vs. 11 per cent respectively (p smaller than 0.01). Exercise tolerance time improved significantly (p smaller than 0.001) in both groups, but more in the group operated on, plus 78 per cent vs. plus 48 per cent, p smaller than 0.05. During a 28-month follow-up period, fewer cardiac complications occurred in the patients operated on--14 vs. 34 (p smaller than 0.02). Mortality was 9 per cent in the patients operated on and 14 per cent in those not operated on; this difference is not significant. The results indicate that improvement, though demonstrable in both groups, is greater with surgery, and quality of life during the first 28 months is better in patients who are operated on.
Changes in placental function during the induction of midtrimester abortion by prostaglandin F2 alpha and hypertonic saline were investigated. Serial estimations of human placental lactogen (HPL) and cystine aminopeptidase (CAP) were carried out in 17 subjects. There was a significant (P smaller than 0.01) reduction in the plasma CAP and HPL levels 4 hours after PGF2 alpha administration. In the case of hypertonic saline abortions only HPL levels showed a reduction at 8 and 12 hours after induction.
Acute infarction was produced in intact conscious dogs by inflating a previously implanted balloon cuff around the left anterior descending coronary artery was occluded in 26 control dogs and reperfused by deflating the balloon cuff after 2 hours of occlusion in 19 dogs (group II) and after 5 hours in 11 dogs (group III). Serial studies were performed and repeated after 48 hours and 7 days. All three groups revealed hemodynamic and metabolic deterioration with coronary occlusion and infarct production. Immediately after reperfusion, arrhythmias developed in groups II and III and persistent ventricular tachycardia was present 2 to 3 hours after reperfusion in 74 percent of animals in group II and 82 percent of those in group III compared with 6 percent and 13 percent incidence rates at corresponding times in control dogs. Q waves developed in 83 percent of animals in group II and 100 percent of those in group III but in only 12 and 27 percent of control animals at corresponding times. Hemodynamic deterioration was accelerated in the postreperfusion period in both groups II and III. Angiographic assessment revealed improvement in 42 percent of dogs in group II, but in none of those in group III after reperfusion. Myocardial oxygen extraction diminished to subnormal levels after reperfusion, indicating either reactive hyperemia or shunting effect. Mortality was not significantly influenced by reperfusion. Infarct size was more than 15 percent of ventricular mass in 92 percent of control dogs and in 100 percent of dogs in group III, but in only 50 percent of those in group II. The data indicate that reperfusion in conscious dogs representing early, noninvasive maximal revascularization under ideal circumstances fails to prevent deterioration or death; instead it hastens the development of arrhythmias and myocardial injury. Reperfusion, although deleterious in the first hours, can reduce infarct size if performed after 2 hours, but not after 5 hours, of occlusion.
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