Use of exercise testing for diagnostic and functional evaluation of patients with arteriosclerotic heart disease

Cardiovascular response to exercise under increasing doses of chlorthalidone

Five male subjects with essential hypertension received chlorthalidone at each of four dose levels (25, 50, 100, and 200 mg/day) for eight week periods each preceded by an eight week placebo period. Dosage order was randomized and double-blind. During the last week of each active and placebo period an upright bicycle exercise study was carried out at three loads (100, 200, 300 kpm/min) for 6 min each. Oxygen consumption at the maximal workload was 42% of predicted at a heart rate of 170. During placebo therapy, increasing workloads were associated with a progressive increase in blood pressure, heart rate, and pressure-rate index (systolic pressure times heart rate). With increasing doses of chlorthalidone up to 100 mg/day, there was a progressive reduction in blood pressure and pressure-rate index. At 200 mg/day there were paradoxical increases in diastolic pressures, heart rates and pressure-rate indices above values observed at 100 mg/day. With increasing doses of chlorthalidone, there was a progressive increase in arterial blood CO2 content and pH. Increasing workloads were associated with increased arterial blood lactate and decreased arterial blood lactate and decreased arterial blood pH. The changes in lactate and pH were not different at the different dose levels. The best antihypertensive effect in these exercising subjects was observed at a daily dose of 100 mg of chlorthalidone. The exercise response was useful in the determination of potentially adverse hemodynamic consequences of the larger dose of chlorthalidone.

Multiple lead ECG submaximal treadmill exercise tests in angiographically documented coronary heart disease

One hundred patients underwent submaximal exercise tolerance testing and coronary cineangiography. Sixty-six percent of the exercise tests were diagnostic including 48 positive and 18 negative tests; 34 patients had indeterminate test results. The occurrence of exercise induced ventricular premature beats was not related to significant coronary artery disease. Ventricular asynergy was significantly more frequent in patients with positive exercise tests (p less than .0001). Application of the age-adjusted target heart rate criterion recommended from Scandinavia and Myrtle Beach to patients with indeterminate results due to failure to reach target heart rate resulted in six false negative tests and lowered sensitivity. The number of positive diagnostic responses achieved using a multiple electrocardiographic lead system was compared with positive diagnostic responses detected in a single lead (V5) and the number of positive tests identified by the additional leads was highly significant (p less than .0001). A high incidence of indeterminate test results due to failure to achieve target heart rate is noted.

Value of exercise testing for screening asymptomatic men for latent coronary artery disease

Treadmill exercise testing identifies a group of men at high risk for coronary atherosclerotic heart disease. However, the predictive value and sensitivity limitations are obvious. An abnormal electrocardiographic response does not absolutely predict the presence of coronary atherosclerotic heart disease, and a normal response does not rule out this possibility. Thus in appropriate instances when the minimal risk of coronary angiography is justified this procedure can be used to determine the anatomic correlation of exercise-induced functional ST-segment changes.

Changes in transthoracic electrical impedance during submaximal treadmill exercise in patients with ischemic heart disease--A preliminary report

Twenty normal subjects and 32 patients with ischemic heart disease (IHD) were subjected to submaximal treadmill exercise. The mean transthoracic electrical impedance (TEI) was measured with a tetrapolar lead system and the changes were correlated to the extent of ST depression observed on an on-line digital computer. Six subjects of pre-excitation syndrome with "false" ST depression were also studied. The normal subjects did not show a significant change of TEI during exercise. The patients with IHD showed a steady and significant decrease in TEI, correlating with the extent of ST depression. Recovery was slow after the cessation of exercise. The subjects with false ST changes showed no decrease of TEI. The changes were more profound in subjects who developed anginal pain during the test. These findings are attributed to an increase in the thoracic blood volume and pulmonary extravascular water due to transient left ventricular dysfunction in angina.

The effects of acute severe arterial hypoxemia on the electrocardiogram during exercise

Sixteen healthy, active men were studied to determine the effects of severe arterial hypoxemia on the electrocardiograms during exercise. The electrocardiograms were all normal at maximum heart rate while the subject breathed ambient air. During maximal exercise breathing ten percent oxygen (mean arterial oxygen pressure [Po2] of 31 mm Hg), only one of the 16 had ST segment changes suggestive of ischemia. These were not present on a repeated study. The widely held view that systemic hypoxemia causes ischemic changes on the electrocardiogram was not confirmed in this study.

Significant sex differences in the correlation of electrocardiographic exercise testing and coronary arteriograms

Two hundred fifty-one patients (195 male and 56 females) referred for evaluation of chest pain were studied by multistage submaximal stress testing and selective coronary arteriography. In men with positive exercise tests the incidence rate of true positive exercise test results--that is, positive tests associated with 75 percent of greater coronary stenosis--was 89 percent in contrast to a 33 percent incidence rate of true positive exercise test results in women. The incidence rate of false positive excercise test results--that is, positive tests associated with no coronary stenosis or less than 50 percent stenosis--was 8 percent in men in contrast to 67 percent in women. Conversely, the incidence rate of false negative exercise test results (that is, negative exercise tests associated with 75 percent or greater coronary stenosis) was higher in men (37 percent) than in women (12 percent). It is concluded that in men a positive multistage stress test is useful in predicting the presence of significant coronary artery disease although a negative stress test cannot be relied upon to rule out the presence of significant disease. In women, a positive exercise test is of little value in predicting the presence of significant coronary artery disease, whereas a negative test is quite useful in ruling out the presence of significant disease. New criteria should be developed for stress testing of women.

Maximal treadmill exercise testing in the management of the post-myocardial infarction patient

Treadmill exercise tests were performed on 32 active duty military personnel 9 to 11 months after acute myocardial infarction to enable more objective selection of candidates for return to military service. Treadmill exercise tests were terminated at heart rates averaging 92 percent maximal predicted rate for age, or when chest discomfort with ischemic ECG changes occurred. The incidence of lipid abnormalities, hypertension, and other coronary risk factors did not differ among the groups. However, treadmill exercise tests appeared to identify a high risk group. Treadmill exercise testing in young postmyocardial infarction patients suggests that those with ischemic responses are at high risk of subsequent cardiac complications. Early surgery in this group may be warranted. The more frequently encountered negative response appears to be associated with a benign clinical course and better immediate prognosis.

Exercise tolerance in patients with angina pectoris after pentaerythritol trinitrate and alprenolol studied by two different methods

Exercise tolerance has been studied by two different methods, heart-rate-controlled exercise and stepwise increased load, in 12 patients with angina pectoris. The response to a beta-adrenergic blocking agent, alprenolol, and an alkyl nitrate derivative, pentaerythritol trinitrate (PETRIN) was studied by the two methods after double-blind administration of the drugs. Rating scales were used to quantitate the degree of dyspnoea, angina pectoris and tiredness in the legs. After PETRIN both methods showed significant increases in exercise tolerance (19 and 21 per cent). The heart-rate-controlled test showed a significant increase (33%) after alprenolol, but the change was not significant by the other method. In the patients studied, heart-rate-controlled exercise discriminated between active drug and placebo better than the stepwise increased load test, what might have been due to more optimal matching of the loads obtained in the heart-rate-controlled test. Indications are given about how to design an exercise study in patients with angina pectoris.

Myocardial ischemic effects of isometric, dynamic and combined exercise in coronary artery disease

The electrocardiographic effects isometric (handgrip) and combined isometric-dynamic (treadmill-plus-brief-case) exercise were evaluated and compared to a submaximal treadmill stress test in 140 patients with known or suspected coronary artery disease. Only 3 of 90 patients developed ischemic ST changes during handgrip, as opposed to 25 positive treadmill tests (p less than 0.01). Of 19 of 50 patients who were positive during the standard treadmill test, only 17 showed positive findings during the combined treadmill-briefcase test. Analysis of hemodynamic responses showed significant (p less than 0.01) differences between the handgrip and treadmill tests in terms of heart rate response (control 83 plus or minus beats/minute, handgrip 105 plus or minus 4, treadmill 151 plus or minus 6), diastolic blood pressure (control 80 plus or minus 2 mm Hg, isometric 93 plus or minus 3, treadmill 81 plus or minus 3) and heart rate-systolic pressure product (control 9940 plus or minus 564 units, handgrip 15022 plus or minus 779, treadmill 22270 plus or minus 1147). In comparing treadmill and combined treadmill-briefcase tests, significant differences were seen in systolic blood pressure (control 114 plus or minus 2 mm Hg, treadmill 143 plus or minus 3, briefcase 155 plus or minus 3), diastolic blood pressure (control 83 plus or minus 2 mm Hg, treadmill 82 plus or minus 2, briefcase 89 plus or minus 2) and rate-pressure product (control 10134 plus or minus 373, treadmill 19624 plus or minus 777, briefcase 21201 plus or minus 798). Isometric exercise alone is much less likely to produce myocardial ischemia than vigorous dynamic exercise. Higher arterial diastolic (coronary perfusion) pressure may retard the development of myocardial ischemia during isometric or combined isometricdynamic exercise in coronary patients.

Comparison of ventricular ectopic activity during 24-hour monitoring and exercise testing in patients with coronary heart disease

The exposure of ventricular ectopic activity (VEA) by maximal exercise testing and 24-hour ambulatory monitoring was compared in 100 unselected patients with coronary heart disease. The arrhythmia was noted with exercise in 56 patients and with monitoring in 88. Repetitive forms such as couplets and ventricular tachycardia were found to be twice as frequent (40 vs. 20) with monitoring than with exercise. Patients with prior myocardial infarction had more frequent ventricular ectopic activity of a more advanced grade with both exercise and monitoring than patients with angina pectoris. Exercise exposed the grades of ectopic activity that recurred during two or more hours of the monitoring session. Of seven patients with ventricular tachycardia on exercise only four exhibited this grade with monitoring. It may be that these two methods divulge different information regarding the electrophysiologic state of the myocardium.

Exercise stress testing in patients with chest pain and normal coronary arteriography: with review of the literature

Eighty of 654 patients studied because of chest pain were found to have normal coronary arteriography. Fifty of these completed submaximal treadmill exercise studies. The purpose of this study was to determine whether treadmill electrocardiography could obviate the need for coronary arteriography in the evaluation of patients with undiagnosed chest pain. Of patients studied, 22% had typical angina pectoris, while 78% had atypical chest pain. The resting electrocardiogram was normal in 58% of patients, while 42% showed repolarization abnormalities. Submaximal treadmill testing was normal in 64%, incomplete in 12%, and demonstrated classic ischemic S-T depression in 24%. Our findings of 24% positive studies in patients with normal vessels and 12% incomplete tests suggest that stress electrocardiography may be of limited value in predicting the morphologic state of the coronary arteries in patients with undiagnosed chest pain.