Serum cholesterol and triglyceride measurements in Canadian physicians.

In a study of serum cholesterol and triglyceride concentrations in male physicians, blood was drawn after fasting from 2071 registrants at 17 Canadian medical meetings from 1968 to 1973. Eight regional medical laboratories participated in the study. About two thirds of the samples were analysed in one of two laboratories to diminish method variations. When chylomicronemia, hyperglycemia or extremely high triglyceride values were detected, suggesting nonfasting, the data were discarded. The mean serum cholesterol value for the total study population was 233.9 plus or minus 1.22 mg/dl and the mean serum triglyceride value, 150.5 plus or minus 2.48 mg/dl. The mean values and the prevalence of elevated values (cholesterol larger than or equal to 250 mg/dl; triglyceride larger than or equal to 150 mg/dl) were related to age. Of the total study population 34.7% had elevated cholesterol values and 36.2% had elevated triglyceride values; only the cholesterol value was elevated in 17.5%, only the triglyceride value in 19.6% and both values were elevated in 16.8%. Although this was not a random sampling of Canadian physicians or of Canadian men, our findings of elevated serum lipid values were similar to those in French Canadian civic workers, American executives and Scandinavians, and somewhat higher than those in the Albany, New York and Framingham populations, but distinctly higher than those reported by a recent Nutrition Canada survey.

The overweight physician.

A total of 456 male physicians, 24-84 years of age, have been studied for their coronary risk factors. Family physicians totalled 59 percent. As a group, only 12 percent of the physicians were of normal weight, 42 percent had a tendency to overweight, and five percent were considered obese. The 456 physicians were divided into two groups, 'normals and 'overweight'. When the two groups were compared it was found that the overweight physicians were more unfit (as evidenced by a lower maximum oxygen uptake), had a greater incidence of hypertension and had a greater number of abnormalities in their resting electrocardiogram. While no difference was noted between the two groups, the overall incidence of hypercholesterolemia was definitely higher than that in the Canadian population.

The maximum oxygen intake. An international reference standard of cardiorespiratory fitness.

Lack of cardiorespiratory fitness may well contribute to the increasing prevalence of degenerative cardiovascular disease throughout the world. As a first step towards co-ordinated and internationally comparable investigation of this problem, methods of measuring the reference standard of cardiorespiratory fitness-the maximum oxygen intake, (Vo(2))(max)-were compared by an international working party that met in Toronto in the summer of 1967.Repeated testing of 24 subjects showed that the (Vo(2))(max) was greatest on the treadmill, 3.4% smaller in a stepping test, and 6.6% smaller during use of a bicycle ergometer. There were also parallel differences in cardiac stroke volume. Uphill treadmill running was recommended for the laboratory measurement of (Vo(2))(max), and stepping or bicycle exercise for field studies. A discontinuous series of maximum tests caused some improvement in the fitness of subjects, and a "continuous" test (with small increases in load at 2-min intervals) was preferred.

Standardization of submaximal exercise tests.

It is often impossible to measure the reference standard of cardiorespiratory fitness (the maximum oxygen intake) directly, and there is thus a need for subsidiary standard procedures based on body responses to submaximal exercise. In order to reach agreement on such procedures, a recent international working party has compared a variety of possible tests involving step, bicycle, and treadmill exercise; criteria of comparison included the extent of habituation and learning with each procedure, the physiological responses, and practical considerations. There was little to commend submaximal exercise on the treadmill. Anxiety and learning were least on the bicycle ergometer, but significant anaerobic metabolism developed at loads of more than 55% of aerobic power; the main role of the bicycle was thus in laboratory tests requiring arm immobilization. The step test was cheap and portable, subjects showed relatively little anxiety or learning, and good-quality electrocardiograms were obtained: it thus seemed the procedure of choice for field tests. The results of all forms of submaximal test should be extrapolated to maximum oxygen intake in order to overcome difficulties arising from differences in the age and fitness of subjects. Four common extrapolation procedures, based respectively on one to four measurements of oxygen consumption and pulse rate, yielded similar predictions of maximum oxygen intake. A single progressive test, in which the exercise load was increased at the end of every third minute, gave an identical prediction of maximum oxygen intake to that obtained from a series of 4 discontinuous tests. The progressive test was thus the preferred procedure; however, in subjects with some circulatory delay, it might be necessary to replace the four 3-min loads by three 4-min loads.

Three years' experience with implanted pacemakers.

At the University Hospital, Saskatoon, over the last three years, pacemakers have been inserted in 40 patients with complete or incomplete heart block. Fourteen of the patients were females and 26 were males. The average age was 65 years; 12 were over 80 years of age, and the youngest patient was 8 years of age. In none was the heart block due to operation. Thirty-three patients are still alive and well. There have been seven deaths three early and four late. One patient died because of a "runaway" pacemaker, and two as a result of infection persisting around the pacemaker. Twenty-nine Medtronic pacemakers were used and 14 Atricor pacemakers; currently we favour the latter instrument.