Fusako Kusumi

Maximal oxygen intake and nomographic assessment of functional aerobic impairment in cardiovascular disease.

Abstract Maximal oxygen intake (Vo 2 max) was measured, using an open circuit technique, during the last 2 to 4 minutes of a multistage treadmill test of maximal exercise in 151 men and 144 women of 29 to 73 years of age. Vo 2 max was higher in men than in women (P Over 800 measurements of Vo 2 max were also made during submaximal exercise to define the aerobic requirements under these conditions of testing. This revealed different coefficients for slope and intercept of regression equation for relationship of Vo 2 submax to duration of submaximal exercise. Functional aerobic impairment (FAI) is the per cent difference between observed (or estimated) Vo 2 max and that predicted from age, sex, and activity status by regression equations. Nomograms for rapid derivation of FAI from age in years and duration of maximal exercise were constructed for healthy men, women, and cardiac men to facilitate clinical usage of these methods. Functional aerobic impairment was 23 per cent in a group of symptomatic hypertensive men; it was 24 per cent in men with healed myocardial infarction, free from angina on maximal exertion, but 41 per cent in men with angina of effort, with or without evidence of prior infarction. In men with either angina or only healed myocardial infarction, impairment was reduced during treatment with nitroglycerin.

Increased Arteriovenous Oxygen Difference After Physical Training in Coronary Heart Disease

A preliminary study of 12 male patients (mean age, 47.8 years) with coronary heart disease (six with angina pectoris and six with prior myocardial infarction but without angina) was conducted according to a common protocol in Seattle, Washington, and Louvain, Belgium. Maximal oxygen intake (Vo2 max) and hemodynamic studies at rest and at two or three levels of submaximal exercise in the upright position were obtained before and after a 3-month physical training program that involved three sessions of 45 min/week. “Vo2 max’ increased 22.5% (P < 0.0001) with physical training. Changes in maximal heart rate occurred in the patients with angina (+8.4%) but not in those without angina (+0.8%). At rest and at each submaximal exercise, heart rate, mean blood pressure, and cardiac output decreased after training, whereas stroke volume was unchanged and arterio-mixed venous oxygen (A-Vo2) difference increased. The pressure-rate product and the left ventricular work decreased after training. The classic posttraining bradycardia was compensated not by a higher stroke volume but by an increased A-Vo2 difference which resulted from both a higher arterial oxygen content and an increased peripheral oxygen extraction. The latter was more apparent when exercises of the same relative intensity were compared.Thus, benefits with physical training in coronary patients result at submaximal exercise level from enhanced arterial oxygen content and peripheral extraction and secondarily from lower hemodynamic stress on ischemic myocardium. Increased maximal A-Vo2 difference probably explains most of the increase in “Vo2 max’ with physical training in coronary patients not limited by angina pectoris.

Variations in Maximal Oxygen Intake with Physical Activity in Middle-Aged Men

Data on maximal exercise performance are presented for normal middle-aged men free of cardiovascular disease. Maximal oxygen intake, oxygen pulse, heart rate, and lactate levels all decrease with increasing age.Physical activity defined by habitual running of any amount had a highly significant effect on maximal oxygen consumption. The enhanced effect of physical activity was found equivalent to nearly 10 years of age effect on maximal aerobic capacity.Multivariate analysis revealed significant association between maximal oxygen intake and several coronary risk factors; specifically, physical activity, vital capacity, cigarette smoking, and body weight. Notably lacking in significance were other known risk factors, serum cholesterol, and blood pressure.Data for maximal oxygen intake on healthy men aged 40 to 70 years are presented by age group and physical activity class; and regression equations are provided for estimation of maximal oxygen intake from age, physical activity status, and duration of the multistage treadmill test. These data should prove useful as normal standards for assessment of aerobic capacity in middle-aged men until such time as larger numbers of data on maximal exercise testing become available.

Acute effects of oral propranolol on hemodynamic responses to upright exercise

Noninvasive measurements of maximal oxygen intake and invasive measurement of systemic and pulmonary arterial pressures, arterial and mixed venous oxygen contents and direct Fick cardiac output are reported for 3 healthy men and 14 men with coronary heart disease. Observations were obtained at supine and sitting rest, during graded levels of upright exercise on a treadmill up to symptom-limited maximal effort and in two periods of recovery. The effects of 40 mg of propranolol orally were ascertained by repeating the measurements 1 to 1 1/2 hours later. The most consistent effect of propranolol was reduction of pressure-rate products at all phases; slowing of heart rate was significant only during exercise and recovery, and the greater slowing was accompanied by a significant increase in stroke volume. These changes were similar in patients with and without evidence of left ventricular impairment greater than 15 percent on exercise testing. Maximal oxygen intake decreased in healthy subjects and decreased slightly in patients with coronary heart disease with less than 15 percent left ventricular impairment or percent deviation of pressure-rate product from age-predicted normal values during the control study. Maximal oxygen intake increased in patients with more than 15 percent left ventricular impairment. Arterial-mixed venous oxygen difference increased after propranolol because of a reduction of mixed-venous oxygen content attributed to greater peripheral extraction of oxygen.

Divergent effects of diltiazem in patients with exertional angina

Fifteen patients with exercise-induced angina were studied at rest and during symptom-limited upright exercise with a Swan-Ganz catheter and an arterial line in place. Cardiac output was measured using the direct Fick principle. The patients were classified on the basis of the mean pulmonary capillary pressure at maximal exercise. In Group I (eight patients) the mean pulmonary capillary pressure was less than 16 mm Hg and in Group II (seven patients) it was greater than 16 mm Hg. Patients in Group II were older and heavier and had more severe angina during exercise and exhibited greater S-T depression at maximal exercise before treatment. Each patient received 120 mg of oral diltiazem and exercise was repeated 1 hour later. In both groups exercise duration was prolonged (Group I, 5.8 ± 3 versus 6.8 ± 3 minutes [mean ± standard deviation], p −5 , p

Maximal cardiac output during upright exercise: Approximate normal standards and variations with coronary heart disease

Abstract The observed normal ranges for age- and weight-adjusted maximal oxygen uptake and age-adjusted maximal heart rate measured during the Bruce protocol are shown for 99 normal sedentary men. On the basis of observations in 10 normal men, the relation between oxygen uptake and cardiac output (measured with the direct Fick principle) was used to estimate normal limits of maximal cardiac output and stroke volume for the 99 normal sedentary men. These normal standards were then used to evaluate the results of 77 studies in patients with coronary heart disease who had various clinical and angiographic findings and who performed symptom-limited upright exercise while cardiac output was measured using the direct Fick principle. Patients with angina and infarction showed the greatest impairment of age- and weight-adjusted maximal oxygen uptake and age-adjusted maximal cardiac output, maximal heart rate and maximal stroke volume when compared with patients with angina or healed infarction alone. Arterial-mixed venous oxygen difference at maximal exercise was comparable in the three groups. The surgical cohort (studled after aortocoronary vein bypass grafting) had significantly higher maximal heart rates. Patients with an ejection fraction of less than 50 percent had significantly impaired age-adjusted maximal cardiac output and stroke volume.

Differences in Cardiac Function With Prolonged Physical Training For Cardiac Rehabilitation

Ten men aged 40 to 68 years with clinical manifestations of cardiovascular disease and who had participated for 2 to 59 months in a physical training program for cardiac rehabilitation were studied. All 10 underwent measurements of maximal oxygen uptake and invasive studies of cardiac output, using the direct Fick method, at rest and at graded levels of exercise in the upright posture. Of four men who left the training program, three continued activities individually. Physiologic measurements were repeated after a lapse of 13 to 38 months (average 23 months). The rate of change in maximal oxygen uptake relative to normal changes with aging was decelerated in four men over an average of 21.8 months and was accelerated in six men over an average of 23.2 months. At comparable oxygen requirements of exercise, stroke volume and cardiac output were unchanged in the former group but significantly decreased in the latter. Arterial oxygen content and arteriovenous oxygen difference increased in both groups. These results show that prolonged physical training results in physiologic adaptations of cardiac rehabilitation even though deterioration of cardiac function with advancing disease is probable in some patients.

Cardiovascular Mechanisms of Functional Aerobic Impairment in Patients with Coronary Heart Disease

Maximal oxygen uptake VO2max) and functional aerobic impairment (FAI) were determined by treadmill test in 42 men with coronary heart disease and in 11 slightly older healthy men. Patients were separated according to occurrence or nonoccurrence of angina with exercise. At rest and at four levels of submaximal exercise on a bicycle ergometer, cardiac output (Q), using the direct Fick principle, heart rate (HR), mean systemic and pulmonary arterial pressures, and arterial-mixed venous oxygen difference (A-V O2 D) were evaluated in relation to relative aerobic requirement (% Vo2max). Q was highly correlated with Vo2, and both the level and the rate of change of Q were lower in patients with angina at all submaximal workloads. Stroke volume (SV) and HR were significantly restricted at the higher workloads. Although peripheral resistance was increased, there was no compensatory increase in A-V O2 D. Both restricted SV and reduced HR are responsible for cardiovascular components of the abnormal FAI found in patients with myocardial ischemia due to coronary arterial disease.

Divergent effects of antihypertensive therapy on cardiovascular responses and left ventricular function during upright exercise

Abstract Maximal oxygen intake (defined by the highest value observed) during upright exercise increased (P In conclusion, antihypertensive therapy reduces pressure and improves ventricular function, but only when hypertension is complicated by clinical manifestations of disease and noncongestive heart failure occurs with exertion. Lesser elevations of the level of blood pressure in asymptomatic persons can be modified by drug therapy, but exercise capacity is not improved.

Reproduction of Maximal Exercise Performance in Patients with Angina Pectoris Despite Ouabain Treatment

Eight patients with a diagnosis of atherosclerotic heart disease and a history of typical angina pectoris, uncomplicated by cardiac dilatation or heart failure, were studied by means of standardized, symptom-limited treadmill exercise test. Repeatability of such testing was determined during two control tests 1-1.5 hours apart. From two to six days later, the same patients performed two treadmill tests after pulmonary and brachial arterial catheterization. The study design allowed evaluation of the effects of 0.005 mg/kg of ouabain at rest-both supine and standing-and during submaximal and maximal exercise.Measurements were made of oxygen uptake, arterial-mixed venous oxygen difference, heart rate, systemic arterial pressures and pulmonary arterial mean pressure. The ratio of mean systemic to mean pulmonary arterial pressure relative to cardiac output indicated that acute left ventricular dysfunction limited aerobic work. Treatment with ouabain did not significantly change performance or capacity and angina was not alleviated.