Biomedical subjects
Publications and source records attributed to J B Irving.
Maximal oxygen consumption [(VO2)max] was measured on three separate occasions over 8 years in 12 healthy men. The decline in (VO2)max with age was less than noted in previous studies and was smallest in men taking regular physical exercise. The presence of ST depression during or after exercise did not influence the decline in (VO2)max.
Twenty-six patients were treated for ventricular septal rupture following myocardial infarction over a five year period. Twenty-three patients underwent full haemodynamic investigation with a view to surgery and nineteen underwent operative closure of the defect. Overall hospital mortality was 47 per cent in the surgical group. Eleven patients had surgery within two weeks of infarction because of marked haemodynamic deterioration soon after septal rupture but only two survived to leave hospital. Eight patients underwent operation two weeks or longer after infaction, all were alive and well at discharge from hospital, six were well at one year and four at three years. Seven patients did not undergo surgery and the maximum survival for these was eight months. No patient in cardiogenic shock before septal rupture benefited from repair. Rapid clinical deterioration following rupture carried a poor prognosis. In all the shunt was large and medical treatment was ineffective. It is concluded that early surgical repair should be considered except when cardiogenic shock antedates the septal rupture.
The features and course of a patient in whom a fistula developed between the left ventricle and the coronary sinus following replacement of a faulty mitral valve prosthesis are described. The subsequent deterioration of her condition was associated with a pansystolic murmur and periprosthetic regurgitation. Replacement by a third prosthesis was complicated in addition by tricuspid regurgitation. The fistula was not suspected until the fourth operation, when the right atrium was opened for tricuspid annuloplasty. The fistula was repaired successfully, and the woman has made good progress postoperatively.
In a follow-up study of 1,852 men with coronary heart disease, 195 deaths occurred within the first 3 years (33 +/- 13 months [mean +/- standard deviation]). Analysis of these cases indicated that the risk of sudden cardiac death in ambulatory men with clinical manifestations of coronary heart disease may be readily estimated from noninvasive clinical and exercise criteria. The important predictors are indexes of the severity of coronary heart disease and impairment of peak left ventricular function demonstrated with symptom-limited maximal exercise. The advantages of these predictors are that they may be elicited on the initial study as well as on follow-up noninvasive examinations of ambulatory patients. The appearance of nonelectrocardiographic predictors in serial examinations may provide an indication for invasive studies and be a more important finding than the ischemic S-T reponse to exertion.
Variations in clinical noninvasive systolic pressure at the point of symptom-limited exercise on a treadmill were examined in six groups of subjects: 5,459 men and 749 women classified into three categories each. Among the men, 2,532 were asymptomatic healthy, 592 were hypertensive and 1,586 had clinical manifestations of coronary heart disease (that is, typical angina pectoris, prior myocardial infarction or sudden cardiac arrest with resuscitation). Among the women, 244, 158 and 347 were in the corresponding clinical categories. None had had cardiac surgery; all had follow-up status ascertained by periodic mail questionnaires. Reported deaths were reviewed and classified by three cardiologists; 140 deaths were attributed to coronary heart disease, 118 of them in the men classified as having coronary heart disease. The majority of maximal systolic blood pressure readings were reported to the nearest centimeter rather than millimeter of pressure. Retesting of 156 persons from 1 to 32 months later showed that pressure values agreed within 10 percent in two thirds, the overall mean difference was only 8.6 mm Hg and the correlation at maximal exercise was superior to that of the resting observations just before exercise. Hypertensive patients had a significantly greater body weight than normotensive persons. Among men, the lowest maximal systolic pressure was observed in the group with coronary heart disease; among women, the lowest mean pressure was found in the healthy group. Patients with coronary heart disease were slightly older, and only the women showed a significant correlation in maximal pressure with age. Only 5 percent of the variation in maximal systolic pressure in the patients with coronary heart disease was due to a shortened duration of exercise. Maximal systolic pressures correlated fairly well (r equals 0.46 to 0.68 for the various groups) with resting systolic pressure, and this relation was independent of the diagnosis of cardiovascular disease in both men and women. Relations between pressure and the number of stenotic coronary arteries and imparied ejection fraction at rest were examined in 22 men without and 182 men with coronary artery disease. Lower maximal systolic pressures were often associated with two or three vessel disease or reduced ejection fraction, or both. The prognostic value of maximal systolic pressure for subsequent death due to coronary heart disease was examined in the men with coronary heart disease. The annual rate of sudden cardiac death decreased from 97.9 per 1,000 men to 25.3 and 6.6 per 1,000 men as the range of maximal systolic pressure increased from less than 140 to 140 to 199 and to 200 mm Hg or more, respectively. Cardiomegaly, Q waves in the resting electrocardiogram and persistent postexertional S-T depression were more common in men with the lowest systolic pressure at maximal exercise.
Six men, clinically diagnosed as having coronary heart disease, had postexertional ventricular fibrillation after maximal exercise testing. The common featureof their treadmill performance was "exertional hypotension," that is, a decrease or a limited increase (10 mm Hg) in systolic blood pressure. All six men were successfully resuscitated with electircal defibrillation. The major indication for electrocardiographic monitoring is the detection of major ventricular arrhythmias and changes in QRS-ST-T of acute myocardial infarction or severe ischemia, all of which are urgent indications for stopping exertion. Close supervision both during and after exercise testing is essential, particularly in men with severe coronary artery disease; monitoring of changes in systolic pressure during and shortly after exercise testing is as important as searching for changes in the -S-T segment.
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The analgesic effect of self-administered nitrous oxide 50%/oxygen 50% ('Entonox" analgesic apparatus) was compared with air given by the same method in a double-blind trial in 81 patients with myocardial infarction. Self-administered nitrous oxide/oxygen, which was associated with a low frequency of side-effects, proved significantly more effective than air in the early relief of severe cardiac pain, but not in the relief of moderate or slight pain or when administration was continued after ten minutes.
The blood-pressure responses to carrying a 15 kg. weight in a shoppong basket, and in a rucksack on the back, were compared in 13 ambulant male patients who were convalescing from an uncomplicated myocardial infarction. In 8 of the patients a sustained-handgrip test was also performed. Carrying the weight in the hand produced a distinct increase in blood-pressure, which did not occur when the weight was carried on the back. There was also a significant increase in blood-pressure during sustained handgrip. In view of the lack of symptoms with these circulatory changes, it is concluded that more specific advice about the possible dangers of sustained static exercise should be given to patients recovering from myocardial infarction.
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The effects of isometric exercise on the maximum amplitude of the praecordial accelerocardiogram (as represented by the DE deflection) have been compared in 6 normal subjects (group 1), 12 patients with aortic stenosis (group 2), and 16 patients with myocardial disease (group 3). Whereas the tachycardia and pressor effects of isometric exercise were identical in all three groups, the normal subjects showed a significant decrease in DE during handgrip of 10 +/- 4 per cent (P less than 0.05) as compared with the insignificant increases of 8.5 +/- 6 per cent (P greater than 0.5), and 4 +/- 3.5 per cent (P greater 0.3) observed in the patients in groups 2 and 3. This response in the normal subjects differed significantly from the responses observed in the patients in groups 2 (P less than 0.02) and 3 (P less than 0.01). Of the patients in each of groups 2 and 3, 50 per cent responded abnormally to handgrip in that they showed a significant increase in DE. In the patients with aortic stenosis this subgroup of patients differed from the remainder in that they had a higher resting cardiac index (P less than 0.05). In the patients with myocardial disease this subgroup was characterized by a significantly lower resting left ventricular end-diastolic pressure (P less than 0.02). It seems, therefore, that those patients who increase DE in response to handgrip tend to have better left ventricular function at rest than those who do not. We suggest that this may be because of increased beta adrenergic activity at rest and during isometric exercise in the subgroup who respond to handgrip with an increase in DE.
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