Effects of propranolol and timolol on left ventricular volumes during exercise in patients with coronary artery disease

The hemodynamic effects of beta-receptor blocking agents on the ejection fraction of patients with coronary artery disease during exercise have been studied previously using radionuclide techniques. Left ventricular volume measurements and the peak systolic pressure/end-systolic volume (PSP/ESV) index have been shown to be variables of left ventricular function that are less influenced by preload and afterload than is ejection fraction. Left ventricular volumes and PSP/ESV were therefore measured in 18 patients with proven coronary artery disease in the control state and after 2 weeks of daily maintenance therapy with either 240 mg propranolol or 60 mg timolol. Values at rest and during symptom-limited upright exercise were compared using the first pass technique and a multicrystal scintillation camera. Left ventricular volumes were measured by the area-length method. Because there was no difference between the propranolol and timolol groups, the results for both groups were combined. The ejection fraction at rest after beta-receptor blocker treatment was not significantly different from pretreatment measurements because of an increase in both end-diastolic and end-systolic volumes (p less than 0.01). However, the value for peak systolic pressure/end-systolic volume (PSP/ESV) index at rest was lower after treatment. The exercise ejection fraction was greater after treatment (p less than 0.01), owing to an increase in end-diastolic volume and unchanged end-systolic volume. In addition, there was a significant improvement in the directional change in the PSP/ESV ratio between rest and exercise from pretreatment to treatment (-1.1 +/- 2.5 to +0.2 +/- 1.2, p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of oral propranolol on rest and exercise left ventricular ejection fraction, volumes, and segmental wall motion in patients with angina pectoris. Assessment with equilibrium gated blood pool imaging.

The effect of oral propranolol on left ventricular ejection fraction, left ventricular volumes, cardiac output, and segmental wall motion was assessed with multigated blood pool imaging both at rest and during supine exercise in 15 patients with angina pectoris. Propranolol had no effect on resting left ventricular ejection fractions. Before propranolol, they did not change during exercise, whereas after propranolol the ejection fractions increased slightly. Exercise left ventricular ejection fractions increased with propranolol in three patients with resting left ventricular ejection fractions of less than 40 per cent. More specifically, left ventricular end-diastolic volume index, end-systolic volume index, stroke volume index, and cardiac index were not altered significantly at rest or during exercise by propranolol. Exercise left ventricular ejection fractions were increased in five and unchanged in eight patients by propranolol. Those patients with increases in left ventricular ejection fractions had a greater change in left ventricular end-diastolic volume indices and a greater change in left ventricular end-systolic volume indices during exercise while on propranolol. Left ventricular segmental wall motion was not altered significantly during exercise by propranolol. We conclude that: (1) Left ventricular functional responses to propranolol during exercise are heterogeneous and not easily predicted; (2) propranolol causes no consistent deterioration in exercise left ventricular ejection fraction even in patients with resting ventricular ejection fractions less than 40 per cent; (3) increased exercise left ventricular ejection fraction with propranolol is contributed to by significant increases in end-diastolic volume during exercise; and (4) gated blood pool imaging is a useful method for characterising rest and exercise left ventricular ejection fractions and left ventricular volumes during propranolol therapy.     

Scintigraphic determination of ventricular function and coronary perfusion in long-distance runners

Left ventricular function and coronary perfusion were evaluated with rest-exercise gated blood pool and stress-redistribution thallium scans in a group of long-distance runners and compared to a group of catheterization-proved normal subjects. Exercise duration, work load, and oxygen consumption were significantly greater for long-distance runners. Rest end-diastolic volume (EDV), end-systolic volume (ESV), and stroke volumes (SV) were significantly larger in long-distance runners than in control subjects, while ejection fraction (EF), cardiac index (CI), and ejection rate were similar in both groups. Exercise EDV increased and ESV decreased, producing an increase in SV and EF in long-distance runners. Exercise EDV did not change and ESV decreased less, producing lesser increase in SV and EF in the control group. Qualitative evaluation of thallium scans showed apparent perfusion defects with normal redistribution in six myocardial segments in five long-distance runners. Quantitative evaluation demonstrated initial defects, which persisted on delay scans, but were associated with normal relative redistribution in three ventricular walls in three long-distance runners. In conclusion, left ventricular reserve function was greater in long-distance runners than in control subjects. Endurance exercise can be associated with apparent myocardial perfusion defects, which may be due to uneven ventricular hypertrophy resulting from the pressure and volume loads imposed by exercise.     

Association between the exercise ejection fraction response and systolic wall stress in patients with chronic aortic insufficiency

We studied the exercise ejection fraction response in 56 patients with chronic aortic insufficiency. All had left ventricular dilatation but preserved resting ejection fraction and minimal or no symptoms. The exercise ejection fraction increased by 0.05 units or greater in 18 (32%) patients (group I), remained within 0.05 units of the resting value in 18 (32%) patients (group II), and fell by 0.05 units or greater in 20 (36%) patients (group III). There were no significant differences among the groups in left ventricular end-diastolic dimension, end-systolic dimension, or fractional shortening by echocardiography or in resting left ventricular volumes and ejection fraction by radionuclide angiography. Left ventricular end-systolic wall stress was significantly higher in group III than in either group I or group II (89 +/- 20 vs 70 +/- 18 and 69 +/- 17 X 10(3) dyne/cm2; p less than .005). At peak exercise there were no differences among groups in systolic blood pressure. However, end-systolic volume increased from 65 +/- 28 to 77 +/- 36 ml/m2 in group III and fell from 50 +/- 21 to 28 +/- 18 ml/m2 in group I during exercise. Thus, at peak exercise end-systolic volume was nearly three times greater in group III than in group I. Although stress could not be determined directly during exercise, the directional changes in its determinants suggest that it also would have been higher in group III patients. A highly significant inverse correlation was present between the ejection fraction response and the change in end-systolic volume (r = -.87, p less than .0001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Echocardiographic assessment of the left ventricle of endurance athletes just before and after exercise

Fourteen normal subjects and 10 marathon runners were studied using postexercise echocardiography to assess left ventricular (LV) wall thickness, afterload and systolic performance. Cuff systolic blood pressures and M-mode echocardiographic recordings were obtained in the supine position before and within 2 minutes of termination of maximal treadmill exercise. Both groups had increased LV dimensional shortening (% fractional shortening) and stroke volume after exercise, although runners had larger increases compared to untrained normal subjects (p less than 0.05). Preload, as estimated by LV end-diastolic dimension, was greater in runners compared to normal subjects at rest (52 vs 48 mm, p less than 0.05). However, preload did not change after exercise in either group. Afterload, estimated by LV end-systolic wall stress, decreased after exercise in both groups; however, runners had lower afterload at rest and immediately after exercise compared to normal subjects (p less than 0.05). The runners' greater LV end-systolic wall thickness appears to account for their lower afterload. Data indicate that marathon runners have lower afterload at rest and greater decrease in afterload after maximal exercise, compared to untrained normal subjects.     

Left and right ventricular function during symptom-limited exercise in patients with isolated mitral stenosis

Ventricular function during exercise in patients with mitral stenosis has not been widely studied. Accordingly, 20 patients with isolated mitral stenosis were assessed during supine, symptom-limited equilibrium radionuclide ventriculographic studies. All patients had a normal left ventricular (LV) ejection fraction at rest (greater than or equal to 50 percent), and all were in sinus rhythm. Left ventricular ejection fraction rose (p less than 0.001) from 64 +/- 9 percent at rest to 74 +/- 11 percent during exercise. This normal response was due solely to a decrease (p less than 0.01) in exercise LV end-systolic volume. A significant (p less than 0.01) decrease in end-diastolic volume during exercise limited the increase in ejection fraction during exercise. The decrease in end-diastolic volume during exercise caused stroke volume to remain unchanged; cardiac output rose according to heart rate alone. Right ventricular (RV) ejection fraction did not rise with exercise due to an increase in end-systolic volume. With exercise, LV end-diastolic volume was smaller (p less than 0.05) with severe mitral stenosis compared to mild mitral stenosis. With exercise, RV ejection fraction was decreased (p less than 0.05) with severe compared to mild mitral stenosis. In conclusion, LV function during exercise is normal in patients with normal resting LV ejection fraction. A decrease in LV diastolic filling with exercise prevents a rise in stroke volume, and cardiac output increases by heart rate alone. With, exercise, RV ejection fraction does not rise, due to an increase in RV end-systolic volume.     

Left ventricular volume and ejection fraction response to exercise in aortic regurgitation

To test the hypothesis that left ventricular (LV) performance in aortic regurgitation (AR) can be more completely characterized by measurement of LV volumes in addition to ejection fraction (EF), 27 asymptomatic patients (Group 1), and 22 symptomatic patients (Group 2), and 10 control subjects were studied at rest and during upright bicycle exercise using the first-pass technique and a multicrystal scintillation camera. LV end-diastolic volume was measured by the area-length method. In the control group end-diastolic volume increased 14%, end-systolic volume decreased 22%, and EF increased 22% with exercise. In contrast, in Group 1 patients with AR, end-diastolic volume was elevated at rest and during exercise. The 18% decrease in end-diastolic volume during exercise was significantly different from the control response (p less than 0.01). End-systolic volume was also elevated at rest and during exercise, but the 30% decrease during exercise was a response not significantly different from the control. Although mean EF increased 15% in these patients, EF at peak exercise was significantly lower than that in the controls. In Group 2 patients with AR, resting EF was reduced, the EF response to exercise was abnormal, and end-diastolic and end-systolic volume responses to exercise were significantly different from those in Group 1: end-diastolic volume did not change and end-systolic volume increased. In contrast to the fairly uniform volume responses among all Group 1 patients, there were 2 subgroups based on volume changes within Group 2: 7 of 22 had a decrease in end-diastolic volume and end-systolic volume during exercise and 8 of 22 showed an increase in end-diastolic and end-systolic volume during exercise. In conclusion, LV volumes at rest and exercise give more information about LV functional reserve in symptomatic patients with AR than do EF responses alone, and may be useful in separating symptomatic patients who show a normal end-systolic volume response to exercise from those in whom worsening failure develops during exercise.     

Echocardiographic assessment of left ventricular performance before and after marathon running

Echocardiography was used to indirectly assess the effects of marathon running on myocardial performance. Thirteen marathon runners (mean +/- SEM:30 +/- 1.6 years) were submitted to a resting echocardiographic examination before racing and during early recovery from marathon racing. Indices of left ventricular performance were computed from M-mode recordings of left ventricular dimensions and aortic valve motions. Comparison of basal and post-marathon indices of left ventricular performance showed no significant differences in either pre-ejection period (PEP), left ventricular ejection index (LVEI), fractional shortening (% delta D), ejection fraction (EF), or mean rate of circumferential fiber shortening (mVcf). Cardiac output (Qc) computed from left ventricular end-diastolic (LVEDV) and end-systolic volumes (LVESV) were significantly higher following marathon running (4.9 +/- 0.4 to 6.7 +/- 0.7 L/min) because of a marked increase in resting heart rate (HR) (58 +/- 3 to 76 +/- 3 bpm). A significant decrease in systolic blood pressure (118 +/- 4 to 108 +/- 3 mm Hg), associated with a slight reduction in calculated total peripheral resistance was also observed after the race. These circulatory adjustments probably reflect thermoregulatory activity that allows a greater blood flow to the skin for heat dissipation, as well as persistence of reactive muscle hyperemia. Echocardiographic evidence suggests that marathon running does not lead to marked impairments in left ventricular performance. However, the absence of change in the end-systolic volume, despite a marked reduction in cardiac afterload, may suggest a slight alteration in contractility that could not be detected with the use of echocardiography.     

Stroke volume increases by similar mechanisms during upright exercise in normal men and women

To define the effects of gender on stroke volume control during upright exercise in normal subjects, we examined central hemodynamics in 34 men and 27 women during staged bicycle ergometry. Central hemodynamics were assessed by right-sided cardiac catheterization and simultaneous radionuclide angiography. Left ventricular end-diastolic and end-systolic volumes were calculated from the stroke volume (by direct Fick) and the corresponding left ventricular ejection fraction. Men were larger than women (1.85 ± 0.11 vs 1.65 ± 0.13 m², p < 0.001) but groups were matched for age (39 ± 12 vs 36 ± 9 years, P = 0.27). Oxygen consumption at peak exercise was higher in men than in women (2.51 ± 0.50 vs 1.74 ± 0.30 liters/min, p < 0.001) but was not different when adjusted for body weight (31.5 ± 8.1 vs 28.4 ± 6.4 ml/kg/min, P = 0.14), indicating similar levels of overall fitness in the 2 groups. At rest and during submaximal and maximal exercise, stroke volume and left ventricular end-diastolic and end-systolic volumes were higher in men than in women, but there were no intergroup differences in stroke volume index, left ventricular ejection fraction, and left ventricular end-diastolic or end-systolic volume indexes. Comparison of derived regression equations of cardiac index, stroke volume index and left ventricular end-diastolic and end-systolic volume indexes revealed no differences in the time course or magnitude of changes with respect to oxygen consumption, expressed as percentage of peak oxygen consumption, in the 2 groups. The major increase in left ventricular end-diastolic volume from upright rest in both men and women occurred during early exercise and accounted for most of the increase in stroke volume with relatively small increases in pulmonary wedge pressure. With moderate to intense exercise, stroke volume was maintained because of decreases in left ventricular end-systolic volume, as left ventricular end-diastolic volume did not change or decreased slightly from 50 to 100% of peak oxygen consumption in both men and women. Our data indicate that in normal subjects, gender, independent of body size and physical fitness, is not an important determinant of cardiac output or left ventricular volume response to upright exercise.     

Effect of long-term high intensity aerobic training on left ventricular volume during maximal upright exercise

The purpose of this study was to determine whether high intensity, long-term aerobic training causes the left ventricle to develop different mechanisms for increasing cardiac output during submaximal and maximal upright bicycle exercise. Fifteen competitive collegiate long distance runners and 14 healthy sedentary adults were studied with use of subcostal view four chamber two-dimensional echocardiography at rest and during and at peak maximal upright bicycle exercise. At rest, the athletes had a larger end-diastolic volume index (85 +/- 14 ml/m2) (mean +/- 1 SD) than that of the sedentary adults (62 +/- 14 ml/m2) and a larger end-systolic volume index (37 +/- 11 versus 21 +/- 6 ml/m2). During low and moderate intensity exercise, end-diastolic and stroke volume indexes increased in both groups, but at high intensity exercise and at peak exercise the end-diastolic volume index of both groups decreased significantly below rest value (athletes, 61 +/- 14; sedentary subjects, 46 +/- 10 ml/m2, both p less than 0.001 compared with rest). Reflecting the decreased end-diastolic volume index, at peak exercise, the stroke volume index had decreased from intermediate exercise values in both groups and was not different from rest values. Therefore, although long distance runners have a dilated left ventricle at rest, they utilize the same mechanisms as sedentary adults for increasing cardiac output during upright dynamic exercise. At low and moderate level exercise, the Frank-Starling mechanism is a dominant mechanism for increasing cardiac output, but at peak exercise, probably because of reduced diastolic left ventricular filling, enhanced contractility is the major mechanism for maintaining stroke volume.     

Left ventricular dimensions and mechanics in distance runners

We assessed heart size and mechanics at rest in highly trained distance runners. By means of two-dimensional echocardiography, we compared 62 runners (greater than 40 miles/week) and 84 nonrunners. Left ventricular end-diastolic volume index and mass index were larger in runners than in nonrunners (p less than 0.001) and in men than in women (p less than 0.001). However, left ventricular end-diastolic and end-systolic volume/mass ratios were similar for runners and nonrunners. Noninvasive estimates of end-systolic and peak-systolic meridional and circumferential wall stresses were lower in runners than in nonrunners (p less than 0.001). Lower wall stress resulted from lower myocardial area/cavity area ratios, and thus 'average' radius/thickness ratios (measured from the parasternal short-axis view), in runners than in nonrunners (p less than 0.001). We detected a subtle change in ventricular shape among the distance runners. Basilar hypertrophy accounted for increased myocardial thickness with normal cavity size in the parasternal short-axis view, as might be expected in hearts working under sustained pressure elevations during prolonged training periods. However, cavity length and therefore ventricular volume were increased in the apical views, leading to a normal overall volume/mass ratio. These hearts have thus adjusted to periods of volume, as well as to pressure overload. Race performance is determined by a complex interaction between the heart, vascular, and skeletal muscle systems. In this study no parameter of myocardial size or function predicted 10 km or marathon race times, just as no physical characteristic or training record predicted left ventricular mass, end-diastolic or end-systolic volume.(ABSTRACT TRUNCATED AT 250 WORDS)     

Improvement of resting myocardial asynergy with cessation of upright bicycle exercise

Exercise generally aggravates ischemic myocardial dysfunction, presumably by increasing tissue oxygen demand out of proportion to the increase in supply. Nevertheless, resting left ventricular (LV) wall motion abnormalities can improve dramatically after upright exercise. To investigate this "paradoxical" phenomenon, we performed upright bicycle exercise equilibrium radionuclide ventriculography in 93 patients with angiographic coronary artery disease. Immediately after exercise, LV end-diastolic volume was similar to the resting level (1 +/- 22% of rest value), but end-systolic volume (ESV) was significantly below (p less than 0.05) that at rest (-11 +/- 32%) and LV ejection fraction increased significantly compared with rest (0.57 +/- 0.16 vs 0.51 +/- 0.13, p less than 0.05). Improvement in resting myocardial asynergy was frequent (115 of 330 abnormal segments), and was observed more commonly in patients without pathologic Q waves and in segments manifesting mild rather than severe asynergy. In 60 additional patients with resting asynergy who were also studied after nitroglycerin (NTG), there was 89% concordance of wall motion response in asynergic segments after exercise and NTG: 71 of 85 segments manifesting improvement with NTG also improved after exercise, and 157 of 172 segments without improvement with NTG also failed to improve after exercise. Despite the similar wall motion response, the mechanism of improvement is probably different from that produced by NTG. With NTG, preload (end-diastolic volume) and afterload (systolic blood pressure) were significantly lower than their resting control levels (p less than 0.05). These changes did not occur after exercise. Instead, an isolated, significant reduction in ESV was noted. These data support the hypothesis that catecholamine stimulation is responsible for paradoxical wall motion improvement after upright exercise.     

Association between left ventricular structure and cardiac performance during effort in two morphological forms of athlete's heart

AIM: The aim of the study was to evaluate in 263 competitive athletes possible correlations between changes induced by different sport activities in left ventricular (LV) structure and cardiac response during maximal physical effort. METHODS: A total of 160 top-level endurance athletes (ATE; swimmers, runners; 28+/-4 years; 98 male) and 103 strength-trained athletes (ATS; weight-lifters, body-builders; 27+/-5 years; male), selected on the basis of training protocol (dynamic vs. static exercise), underwent standard Doppler echocardiography, heart rate variability analysis and maximal exercise stress test by bicycle ergometry. M- and B-mode echocardiographic LV measurements were determined at rest, while the following functional indexes were assessed during effort: maximal heart rate (HR), maximal systolic blood pressure (SBP) and maximal workload (Watts reached by bicycle test). RESULTS: The two groups were comparable for age and sex, but ATS at rest showed higher HR, SBP, and body surface area (BSA). By echo analysis, LV mass index and ejection fraction did not significantly differ between the two groups. However, ATS showed increased sum of wall thickness (septum+posterior wall), relative wall thickness and LV end-systolic stress, while LV stroke volume and LV end-diastolic diameter (P<0.01) were greater in ATE. HR variability analysis underlined in ATE increased indexes of vagal tone (P<0.01). During maximal physical effort, ATE showed a better functional capacity, with greater maximal workload (P<0.001) reached with lower maximal HR and SBP. After adjusting for HR, age, sex, BSA and SBP, distinct multiple linear regression models evidenced in ATE independent associations of maximal effort workload with LV end-diastolic diameter (P<0.001), HR (P<0.001) at rest and LV end-systolic stress (P<0.01) were found in ATE. On the other hand, independent direct correlation of SBP max during effort with sum of wall thickness (P<0.001), BSA (P<0.05) and LV end-systolic stress (P<0.001) was evidenced in ATS. CONCLUSIONS: LV structural changes in competitive athletes represent adaptation to hemodynamic overload induced by training and are consistent with different kinds of sport activity. Work capacity during exercise is positively influenced by preload increase in ATE, while increased afterload due to isometric training in ATS determines higher systemic resistance during physical effort.     

Effect of nitrates on left ventricular size and function during exercise: Comparison of sublingual nitroglycerin and nitroglycerin paste

To compare the effects of sublingual nitroglycerin and nitroglycerin paste on left ventricular size and performance during supine bicycle exercise, equilibrium radionuclide angiography was performed in 36 persons classified into two groups of normal subjects and two groups of patients with angiographically proved coronary heart disease. Each group underwent a control exercise study, and then one group of normal subjects and one group of patients were restudied after the administration of 0.6 mg of nitroglycerin or 2 inches (5 cm) of nitroglycerin paste (but not both). Data were collected at rest and at peak exercise.In normal subjects exercise resulted in increased ejection fraction, decreased end-systolic volume and little change in end-diastolic volume. After either drug, volumes at rest markedly decreased, and during exercise, ejection fraction increased to levels comparable with pre-drug levels. After nitroglycerin paste the reduction in volume seen at rest persisted during exercise, but after sublingual nitroglycerin end-diastolic volume increased during exercise (88 ± 43 to 113 ± 30 ml [mean ± standard deviation]; p < 0.01). Peak exercise end-diastolic volume after nitroglycerin was still lower than that before nitroglycerin (113 ± 30 versus 120 ± 28 ml, p < 0.05).In patients with coronary disease, ejection fraction did not change during exercise, but both end-diastolic and end-systolic volumes increased. After either drug ejection fraction at rest was unchanged, although ventricular volumes were markedly lower (p < 0.05). Ejection fraction increased with exercise in both groups with coronary disease after either drug. After sublingual nitroglycerin, volumes increased during exercise although the peak exercise end-diastolic volume was still lower than the control value (113 ± 31 versus 145 ± 34 ml; p < 0.01). After paste administration, end-diastolic volume did not change during exercise, and end-systolic volume decreased (41 ± 20 to 36 ± 22 ml; p < 0.05).Thus, sublingual nitroglycerin and nitroglycerin paste improved left ventricular function during exercise. The effect of paste on end-diastolic volume appeared sustained, whereas that of sublingual nitroglycerin was transient, confirming the hypothesis that reduction in end-diastolic volume and, by implication, left ventricular wall tension, is a major mechanism of nitrate action.     

Abnormal exercise hemodynamics in cardiac allograft recipients 1 year after cardiac transplantation. Relation to preload reserve

The well-established elevation in left ventricular filling pressures during exercise in patients after transplantation may contribute to decreased exercise tolerance. A proposed mechanism for this increase in filling pressures is an abnormal pressure-volume homeostasis of the transplanted heart. Twenty-three patients undergoing routine 1-year evaluations performed supine bicycle exercise during right heart catheterization. Within 24 hours, these patients underwent supine bicycle exercise to the identical work load during radionuclide ventriculography. For the group, resting hemodynamics and resting left and right ventricular ejection fractions were normal. With exercise, right atrial and pulmonary wedge pressure rose markedly (from 6 +/- 2 to 14 +/- 7 mm Hg, p less than 0.0001, and from 10 +/- 3 to 20 +/- 6 mm Hg, p less than 0.0001, respectively). Left ventricular ejection fraction increased appropriately with exercise (from 0.58 +/- 0.08 to 0.63 +/- 0.07, p = 0.004). End-diastolic volume also increased mildly (from 100 +/- 31 to 117 +/- 39 ml, p = 0.001), but change in end-diastolic volume was highly variable. Patients with little or no change in end-diastolic volume with exercise had the greatest resting and exercise left ventricular filling pressures resulting in significant negative correlations between filling pressures and change in end-diastolic volume (r = -0.64, p = 0.002 and r = -0.50, p = 0.025, respectively). Negative linear relations between exercise left ventricular filling pressures or resting heart rates and donor to recipient body weight ratio (r = -0.35, p = 0.10, and r = -0.37, p = 0.06, respectively) suggested that initial donor heart size influenced subsequent cardiac function.(ABSTRACT TRUNCATED AT 250 WORDS)     

Left and right ventricular function at rest and during bicycle exercise in the supine and sitting positions in normal subjects and patients with coronary artery disease. Assessment by radionuclide ventriculography

To assess the hemodynamic influence of posture during radionuclide cardiac studies, rest and exercise electrocardiographically gated blood pool cardiac scintigraphy was performed in the supine and sitting positions in 22 normal subjects and in 20 patients with coronary artery disease (CAD). In normal subjects, left ventricular ejection fraction was higher in the sitting position both at rest (67 +/- 6% versus 64 +/- 5%, p less than 0.01) and during exercise (79 +/- 9% versus 76 +/- 6%, p less than 0.05). Left ventricular end-diastolic volume in the sitting position was smaller at rest (by 19 +/- 26%, p less than 0.001), but this variable was similar in both positions during exercise (p greater than 0.05). Left ventricular end-systolic volume was smaller in the sitting position both at rest, by 26 +/- 31 percent, and during exercise, by 14 +/- 20% (p less than 0.001). Left ventricular end-diastolic volume increased from rest to exercise, in the sitting position by 31 +/- 23% (p less than 0.001) and in the supine position by 6 +/- 22% (p greater than 0.05). In patients with CAD, similar left ventricular ejection fractions in both postures were found at rest and during exercise. Left ventricular end-diastolic volume in the sitting posture was smaller at rest by 16 +/- 22% (p less than 0.01) and during exercise by 8 +/- 18% (p less than 0.05). Sitting left ventricular end-systolic volume was smaller by 18 +/- 20% (p less than 0.001) at rest and by 14 +/- 21% (p less than 0.01) during exercise. Left ventricular end-diastolic volume increased from rest to exercise, in the sitting position by 45 +/- 36% (p less than 0.001) and in the supine position by 32 +/- 51% (p less than 0.01). Despite significant hemodynamic differences, the value of rest-exercise radionuclide cardiac studies to detect CAD was similar in the 2 positions.     

Comparison of effects of isometric and supine bicycle exercise on left ventricular performance in patients with aortic regurgitation and normal ejection fraction at rest

The effects of handgrip and supine bicycle exercise on hemodynamics and left ventricular (LV) performance were compared in 25 patients with moderate to severe aortic regurgitation (AR) and normal LV ejection fraction at rest (greater than or equal to 50%) and in 10 control subjects. In both groups, heart rate, systolic blood pressure, rate-pressure product, and LV output were higher during supine bicycle exercise. Compared with the controls, in patients with AR, stroke volume was unchanged during supine bicycle exercise. LV end-diastolic volume increased during handgrip exercise but was unchanged during supine bicycle exercise. LV end-systolic volume increased and ejection fraction decreased during both forms of exercise. Of 25 patients with AR, 15 (60%) during handgrip exercise and 19 (76%) during supine bicycle exercise had an abnormal ejection fraction response (p less than 0.05). In patients with moderate to severe AR and normal LV ejection fraction at rest, both handgrip and supine bicycle exercise induced LV dysfunction. An abnormal LV ejection fraction response occurred more often with supine bicycle exercise. Handgrip exercise may be a useful alternative method for detecting LV dysfunction in patients with AR in whom adequate bicycle exercise cannot be accomplished.     

Quantitative radionuclide angiography in assessment of hemodynamic changes during upright exercise: observations in normal subjects, patient with coronary artery disease and patients with aortic regurgitation

Quantitative radionuclide angiography (with the first pass technique and a computerized multicrystal camera) was used to evaluate hemodynamic changes in three subject groups during symptom-limited upright exercise. The 12 normal subjects had significant increases in heart rate, stroke volume, left ventricular ejection fraction and cardiac output during exercise; changes in end-diastolic and end-systolic volumes were not significant. In the 24 patients with coronary artery disease there were significant increases in heart rate and cardiac output during exercise, but insignificant changes in end-diastolic, end-systolic and stroke volumes and ejection fraction. The change in diastolic volume in these patients was determined by the extent of coronary artery disease, propranolol therapy, end point of exercise and presence of collateral vessels. Furthermore, patients with previous myocardial infarction had a lower ejection fraction and higher end-diastolic and end-systolic volumes during exercise than those without myocardial infarction. In the 12 patients with chronic aortic regurgitation of moderate to severe degree, there was a decrease in the end-diastolic volume during exercise. This response was distinctly different from that of the normal subjects or the patients with coronary artery disease. All three groups had a significant decrease in pulmonary transit time during exercise. It is concluded that changes in cardiac output in normal subjects during upright exercise are related to augmentation of stroke volume and tachycardia, whereas in patients with coronary artery disease they are related mainly to tachycardia. Left ventricular dilatation during exercise occurred in some normal subjects and in patients with coronary artery disease but was not a consistent finding. However, a decrease in left ventricular end-diastolic volume is common in patients with aortic regurgitation. Such a decrease may be explained by a reduction in the regurgitant volume per beat caused by shortening of the diastolic filling period or a decrease in systemic vascular resistance, or both.     

Left ventricular function at rest and during exercise in congenital complete heart block: A radionuclide angiographic evaluation

This study evaluates intrinsic cardiac performance during upright exercise in patients with congenital complete heart block. Left ventricular ejection fraction and volume were measured at rest and peak upright exercise with radionuclide angiography in 5 patients aged 11 to 39 years with congenital complete heart block: 4 were in New York Heart Association class I and 1 was in class II. The resting cardiac output was maintained at a normal level by an increase in end-diastolic volume rather than by a decrease in end-systolic volume. The left ventricular ejection fraction was normal at rest in all patients, but an abnormal response to exercise was noted in 3 patients. There was no appreciable change in the end-diastolic volume during exercise. Thus, patients with congenital complete heart block utilize the Starling mechanism to maintain normal resting cardiac output, but the response to exercise is usually abnormal even in the absence of symptoms.     

Left ventricular dynamics during exercise in elite marathon runners

To assess left ventricular structure and function at rest and during exercise in endurance athletes, 10 elite marathon runners, aged 28 to 37 years, and 10 matched nonathletes were studied by echocardiography and supine bicycle ergometry. Each athlete's best marathon time was less than 2 h 16 min. Echocardiography was performed at rest, at a 60 W work load and at an individually adjusted work load, at which heart rate was 110 beats/min (physical working capacity 110 [PWC110]). Oxygen uptake at PWC110 averaged (+/- SD) 1.14 +/- 0.2 liters/min in the nonathletes and 2.0 +/- 0.2 liters/min in the runners (p less than 0.001). The left ventricular internal diameter at end-diastole was similar at the three activity levels in the control subjects but increased significantly from rest to exercise in the runners (p less than 0.001). Left ventricular systolic meridional wall stress remained unchanged during exercise in the nonathletes but was significantly higher at PWC110 in the athletes (p less than 0.05). Both the systolic peak velocity of posterior wall endocardial displacement and fractional shortening of the left ventricular internal diameter increased with exercise; at PWC110 the endocardial peak velocity was higher in the runners than in the control subjects (p less than 0.01). The endocardial peak velocity during relaxation was comparable in athletes and control subjects at rest, increased similarly at a 60 W work load, but was higher in the runners at PWC110 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)