Submaximal Supine Exercise Research Articles

Hemodynamic changes in pulmonary circulation induced by effort in the elderly

Age-related changes in vascular tissue were previously reported. 1,2 Moreover, mild diffuse connective tissue proliferation of the aging lung can contribute to reduced reserve of the pulmonary vascular bed. 3 These morphologic changes may induce some hemodynamic impairment of the aging pulmonary circulation. Unlike the systemic circulation, relatively little is known regarding the effects of effort on pulmonary hemodynamics in healthy, elderly subjects. Difficulties in selecting elderly subjects without pulmonary vascular, cardiac and lung disease, and the absence of an effective, noninvasive method for the measurement of pulmonary hemodynamics are the causes for this poor knowledge. 4 In the present study, we evaluated the pulmonary hemodynamics in an elderly cohort, free of cardiovascular and lung disease, at rest and during submaximal supine exercise.

Exertional hemodynamics in women with chest pain—an aortic doppler ultrasound study–B. Janerot Sjoberg et al.: Women during exercise

Aortic ultrasound Doppler recordings of stroke volume, maximal flow velocity, and acceleration can be used to assess central hemodynamic effects of exercise in coronary artery disease (CAD) and left ventricular dysfunction. We wanted to evaluate the time course and amplitude of changes in aortic Doppler ultrasound parameters in women during supine exercise and the potential diagnostic value of a submaximal supine exercise test. For this purpose, 18 women who had undergone coronary angiography because of incapacitating chest pain (10 with significant coronary stenoses and previous myocardial infarction, 8 without stenoses or infarction) were compared with 10 healthy controls. Pathological electrocardiographic (ECG) ST-segment depression during supine exercise was common in all groups. In the control group, a significant increase of stroke volume (10%), maximal aortic flow velocity (27%), and acceleration (43%) occurred at low load during exercise. Women with CAD showed no increase and a lower cardiac output during exercise, indicating left ventricular dysfunction. Women with syndrome X resembled the controls but had a higher maximal flow velocity at rest, which may indicate hyperdynamic circulation. We conclude that a test up to 40% of seated maximal load is valuable and often sufficient when assessing the hemodynamic effects of supine exercise by Doppler ultrasound in terms of stroke volume, maximal flow velocity, and acceleration. By characterizing left ventricular function in groups of female patients where false-positive stress ECG reactions are common, Doppler ultrasound may contribute to the understanding and clinical management of women with chest pain.

The hemodynamic importance of atrial systole: a function of the kinetic energy of blood flow?

The relative importance of atrial systole on left ventricular filling was investigated at rest and during exercise in 25 patients with dual chamber pacemakers. The mean blood flow velocity over the mitral valve, the velocities of the rapid filling phase (E), the active filling phase (A), and the E/A ratio were determined by pulsed Doppler-echocardiography. The patients were first examined at rest during AV sequential pacing (DVI) at 70 and 104 beats/min. The investigation was subsequently repeated during atrial synchronous pacing (VDD) at rest and during supine submaximal exercise at workloads adjusted to achieve heart rates corresponding to those during DVI pacing. The mean blood flow velocity at rest did not differ between DVI and VDD pacing at 70 beats/min (0.46 vs 0.49 m/sec). When the resting heart rate was increased to 104 beats/min (DVI) the mean blood flow velocity increased to 0.56 msec (P < 0.001). At a corresponding heart rate during exercise (VDD) the velocity increased to 0.70 msec (P < 0.001). At a resting heart rate of 70 beats/min the E/A ratio (n = 14) did not differ significantly between DVI and VDD pacing. With an increased resting heart rate (DVI) the E/A ratio decreased from 0.94 +/- 0.45 to 0.78 +/- 0.18; NS. When the heart rate increased during exercise (VDD) the E/A ratio increased from 0.75 +/- 0.14 to 0.97 +/- 0.16; P < 0.001. There was a positive correlation between the increase of the mean blood flow velocity and the increase of the E/A ratio during exercise (r = 0.69, P < 0.01). No such correlation was found when the heart rate was changed at rest. Thus, the importance of atrial systole on ventricular filling diminishes during exercise in accordance with increasing blood flow velocity, which by physical principles is related to the kinetic energy. The relative importance of atrial systole is hence inversely correlated to the kinetic energy of the blood flow.

Coronary vasodilatation and improved myocardial lactate metabolism after angiotensin converting enzyme inhibition with cilazapril in patients with congestive heart failure

The effects of angiotensin converting enzyme inhibition on systemic and coronary hemodynamics and on myocardial lactate metabolism were investigated before and 2 and 6 hours after cilazapril at rest and during supine submaximal exercise in 10 patients with New York Heart Association class II or III chronic congestive heart failure. Angiotensin converting enzyme inhibition, indicated by a significant increase in plasma renin activity, resulted in significant reductions in blood pressure and systemic vascular resistance. Myocardial oxygen demand decreased (resting double product 10.9 ± 3.7 vs 12.2 ± 3.8 mm Hg beats/min 10 −3; p < 0.05), but coronary sinus blood flow remained unchanged and calculated coronary resistance decreased (0.45 vs 0.5 units, rest 6 hours; p < 0.05) suggesting coronary vasodilatation. Changes in coronary vascular resistance were directly related to changes in systemic vascular resistance ( r = 0.75, p < 0.5). Myocardial lactate extraction increased at rest (47 ± 60 vs 134 ± 132 μmol/min; p < 0.5) and during exercise (27 ± 54 vs 491 ± 317 μmol/min; p < 0.05) both in patients with coronary artery disease (n = 5) and idiopathic dilated cardiomyopathy (n = 5). Resting lactate production was converted to lactate extraction in two patients with coronary artery disease. Neither plasma catecholamine nor atrial natriuretic peptide concentrations changed significantly. The results suggest coronary vasodilatation and improved aerobic myocardial metabolism by angiotensin converting enzyme inhibition in patients with congestive heart failure.

Inheritance of blood pressure and haemodynamic phenotypes measured at rest and during supine dynamic exercise

Thirty-two pairs of monozygotic and 21 pairs of dizygotic male twins aged between 18 and 31 years were studied. Blood pressure was measured and Doppler echocardiography at the level of the aorta was performed in resting conditions and at two levels of supine submaximal bicycle exercise (at a fixed work load of 60 W and at a work load corresponding to a heart rate of 110 beats/min). In resting conditions, a genetic component in the variability of systolic and diastolic blood pressure was found; during submaximal supine exercise only a minor genetic effect was observed. At rest, genetic variance was shown for left ventricular outflow haemodynamics and for peripheral vascular resistance. However, during exercise, the transmissible effect on haemodynamics and peripheral resistance was small.

Radionuclide studies of left ventricular function in normal subjects

The effects of age and exercise on cardiac function in a normal male population have been assessed by ECG-gated radionuclide ventriculography. Fifty-nine subjects aged from 25 to 54 years were studied (mean 44 +/- 10 S.D. years). Resting left ventricular ejection fraction (LVEF) was 0.54 +/- 0.07 and this increased by 0.07 +/- 0.05 during supine submaximal exercise at 75 watts. The mean increase in cardiac output on exercise was 93 +/- 30%. Stroke volume increased on exercise by 23 +/- 13% and end-systolic volume decreased by 10 +/- 16%. There was a weak correlation (P less than 0.05) between age and change in LVEF on exercise but the increase in cardiac output on exercise was not age dependent. It is important to use an age matched control population in any study of cardiac function.

Exercise doppler echocardiography in patients with mitral prosthetic valves

Submaximal supine exercise was done by 17 patients with mitral prostheses. Eleven had Björk-Shiley (BS) and six had Starr-Edwards (SE) valves. In 15 patients with normally functioning prostheses, valve area at rest was 2.4 ± 0.25 cm 2 in the BS patients and 1.8 ± 0.35 cm 2 in the SE group ( p < 0.01). In the SE group, peak and mean gradients increased from 8 ± 1 and 5 ± 1 mm Hg, respectively, at rest to 22 ± 5 and 13 ± 4 mm Hg at peak exercise (mean ± 1 SD). In the BS group, peak and mean gradients increased from 10 ± 3 and 5 ± 2 mm Hg, respectively, at rest to 16 ± 3 and 10 ± 3 mm Hg at peak exercise. Peak pressure gradient at peak exercise and the increase in peak gradient with exercise (exercise-resting gradient) were significantly higher in the SE group ( p < 0.05). By plotting the heart rate versus the transmitral gradient during the recovery period, a heart rate-gradient curve was obtained for each type of prosthesis. Doppler echocardiography with moderate supine exercise can be performed in most patients with mechancal prosthesis. Hemodynamic properties (the occlusive character of the SE prosthesis) were brought out by exercise. Doppler echocardiographic measurements during exercise can provide important information, particularly in patients with borderline measurements at rest.

Effects of supine exercise on fetal heart rate in the second and third trimesters.

The effects of a brief period of supine exercise on fetal heart rate (FHR) was studied in 25 healthy, regularly exercising women, 12 in the late second trimester and 13 in the mid third trimester. Although statistically significant increases in maternal mean arterial pressure and pulse occurred, the exercise intensity was mild, with the average percent maximal pulse being 46 +/- 5% and 49 +/- 5% in the second and third trimester groups, respectively. Small increases in FHR were seen in both groups, which were insignificant statistically and physiologically. No patient experienced significant FHR abnormalities as a result of the supine exercise sequence. The findings suggest that pregnant women may continue submaximal supine exercise of short duration into the mid to late third trimester.

Effects of Digoxin on Exercise Capacity and Right Ventricular Function during Exercise in Chronic Airflow Obstruction

We evaluated 12 patients with stable chronic airflow obstruction (CAO) and no clinical evidence of left ventricular disease to determine the effects of oral digoxin on exercise capacity (VO2 max) and on right ventricular pump function during exercise. In this randomized, double blind, placebo controlled, cross-over study, patients performed exercise tests and underwent measurement of ejection fractions after two weeks of therapy with oral digoxin (0.25 mg/day) and after two weeks of placebo. Incremental upright exercise testing to a symptom-limited maximum was performed on a cycle ergometer. Right and left ventricular ejection fractions (RVEF, LVEF) were obtained in the supine position at rest and at approximately 75 percent of the maximum workload by gated equilibrium radionuclide angiography. All patients had abnormal right ventricular function, manifested either by a low resting RVEF (less than 45 percent) or a subnormal response to exercise (less than 5 percent increase). The small increases in RVEF with digoxin (mean +/- SE) at rest (44 +/- 5 vs 41 +/- 4 percent) and during exercise (46 +/- 4 vs 44 +/- 3 percent) did not achieve statistical significance. With digoxin, small increases in exercise duration (10.0 +/- 1.5 vs 9.0 +/- 1.4 min), maximum workload achieved (48 +/- 6 vs 42 +/- 5 W), VO2 max (0.85 +/- 0.06 vs 0.81 +/- 0.06 L/min), and oxygen-pulse (O2-P) (6.6 +/- 0.5 vs 6.3 +/- 0.4 ml/beat) occurred. Only the increase in O2-P was significant (p less than 0.05). From this study we conclude that digoxin does not significantly improve exercise capacity in severe chronic airflow obstruction with impaired right ventricular function, nor does it improve RVEF either at rest or during supine submaximal exercise.

Localisation of single vessel coronary artery disease by exercise electrocardiography and thallium scanning

Localisation of single vessel coronary artery disease by exercise electrocardiography and thallium scanning

Assessment of function of contractile segments in patients with left ventricular aneurysms by quantitative first pass radionuclide ventriculography. Haemodynamic correlation at rest and exercise.

Thirteen patients with left ventricular aneurysms complicating myocardial infarction were studied by contrast angiography and by first pass radionuclide ventriculography. The ejection fraction of the contractile segment (EFCS) was measured from both studies using a double hemishperoid model, and the values correlated closely. There was a monotonic relation between EFCS and stroke volume index measured from thermodilution cardiac outputs carried out simultaneously with the radionuclide study. When radionuclide ventriculography was performed at submaximal supine exercise, changes in EFCS paralleled changes in the total left ventricular ejection fraction in 10 of the 13 cases. In nine patients, changes in EFCS paralleled changes in stroke volume index and the relation between EFCS and stroke volume index was maintained at exercise. After administration of the vasodilator isosorbide dinitrate to 12 patients, repeat exercise radionuclide ventriculography showed an improvement in left ventricular ejection fraction and in eight patients EFCS improved. First pass radionuclide ventriculography can accurately estimate EFCS, which may be an important factor in predicting the likely response to aneurysmectomy. Changes in EFCS on exercise are reflected in changes in total left ventricular ejection fraction and stroke volume index. Isosorbide dinitrate may improve contractile segment function on exercise.

Prognostic Value of Radionuclide Ventriculography After Myocardial Infarction

We have studied 50 consecutive patients who had sustained their first myocardial infarction. Using the noninvasive technique of radionuclide ventriculography, ventricular performance, as assessed by left ventricular ejection fraction (EF), was measured at rest just before discharge from hospital when patients were well and free from cardiac failure and then at one and four months after infarction, at rest and during submaximal supine exercise. Left ventricular ejection fraction was below normal in 42 patients (normal range 0.43-0.71). Mean EF for those patients recovering from inferior infarction was 0.43 +/- 0.09 (mean +/- 1 S.D.), whereas for those who had sustained anterior infarction mean EF was significantly lower, 0.33 +/- 0.13 (p less than 0.01). EF was significantly reduced (p less than 0.01) in those patients whose early progress was complicated either by serious arrhythmia or left ventricular failure. There was only poor correlation between EF and radiographically determined heart size but global left ventricular performance correlated well with the presence of abnormalities of regional wall movement. Over the first four months low EF failed to improve in seven patients with areas of dyskinesis (EF less tha 0.30) and despite diuretic therapy five suffered further episodes of cardiac failure. Excluding those with dyskinesis there were 18 patients who were unable to increase EF on exercise on month after infarction. Of these four already had symptoms of angina but a further 10 patients developed angina in the subsequent three months. Poor left ventricular performance is common after anterior myocardial infarction, complicated in the acute phase by serious arrhythmia or left ventricular failure. Patients with persistently low EF had an increased risk of further episodes of cardiac failure, whereas a fall in EF on exercise was associated with subsequent angina.

Exercise thermoregulation after 14 days of bed rest.

Rectal (Tre) and mean skin (Tsk) temperatures and sweating responses were measured during 70-min submaximal supine exercise (relative VO2 43-48%) in seven men (19-22 yr) during an ambulatory-control (AC) period and after three 2-wk bed-rest (BR) periods separated by 3-wk ambulatory recovery periods. During each of the three BR periods they performed isometric exercises (IME) or isotonic exercises (ITE) for 1 h/day or no prescribed exercise (NOE). Mean basal oral temperature decreased from 36.0 to 35.7 degrees C in the last 10 days of the control-recovery periods, but it varied between 35.7 and 35.9 degrees C during BR. In the exercise-temperature test the equilibrium level of Tre for the IME (37.92 degrees C) and NOE (37.75 degrees C) regimens were higher (P less than 0.05) than the AC level of 37.51 degrees C. Mean skin temperatures with the IME and ITE regimens increased by only 0.4 degrees C during exercise, and both equilibrium Tsk values, 31.98 degrees C and 31.87 degrees C, respectively, were lower (P less than 0.05) than the AC values of 32.71 degrees C. There were no significant differences between any of the sweat rates (range, 438-565 g/h) in the four experiments, but calculated skin heat conductances (Hsk) correlated +0.86 with equilibrium levels of Tsk. It was concluded that the excessive increase in Tre during submaximal exercise following BR deconditioning could be influenced by changes in Hsk, but inhibition of sweating may also be a factor.

Improvement in exercise haemodynamics by isosorbide dinitrate in patients with severe congestive cardiac failure secondary to ischaemic heart disease.

Seven patients with severe chronic congestive cardiac failure secondary to ischaemic heart disease performed submaximal supine exercise before and after 5 mg sublingual isosorbide dinitrate at the time of cardiac catheterisation. Exercise before isosorbide dinitrate produced a poor response in left ventricular performance. After isosorbide dinitrate this response was significantly improved. Compared with the control exercise period, cardiac index increased from mean 2.6 to 3.1 1/min per m2 (P less than 0.0025), stroke volume index from mean 22 to 27 ml/m2 (P less than 0.0025), and left ventricular stroke work index from mean 21 to 30 g m/m2 (P less than 0.01). Mean left ventricular filling pressure fell from 37 to 26 mmHg (P less than 0.01). Although isosorbide dinitrate reduced left ventricular filling pressure at rest from mean 26 to 17 mmHg (P less than 0.005), there was no significant change in mean cardiac index or stroke volume index, while left ventricular stroke work index decreased from mean 29 to 22 g m/m2 (P less than 0.05). Isosorbide dinitrate effectively reduces left ventricular filling pressure in the resting patient with congestive cardiac failure but produces a more comprehensive improvement in left ventricular performance during exercise.

Submaximal exercise testing after acute myocardial infarction: Myocardial scintigraphic and electrocardiographic observations

The relation between global and regional left ventricular function and electrocardiographic signs of ischemia at rest and during submaximal supine exercise was studied in 27 patients 2 to 3 weeks after acute myocardial infarction. Dynamic myocardial scintigraphy was performed at rest and during submaximal exercise utilizing an in vivo method of labeling red blood cells with technetium-99m pertechnetate. Gated radio-nuclide blood pool scintigrams were obtained in a modified left anterior oblique, and in some patients also in the right anterior oblique projection, to measure left ventricular ejection fraction and segmental wall motion. Electrocardiographic monitoring of heart rate and rhythm was provided during the exercise. The submaximal exercise test was terminated when the patient's heart rate reached 125 beats/min or if angina, malignant ventricular ectopy or electrocardiographic evidence of myocardial ischemia developed before this rate was reached. The data demonstrate that patients with a recent anterior myocardial infarct, in contrast to patients with a recent inferior or nontransmural infarct, manifest a significant reduction in left ventricular ejection fraction with submaximal exercise. Of the eight patients with an anterior infarct, seven had segmental wall motion abnormalities at rest. Four of these eight manifested more severe abnormalities with submaximal exercise; three had abnormalities at rest that did not change with exercise. Four of the eight had a positive electrocardiographic response during exercise (two were taking digoxin). Of these four, only two had more marked wall motion abnormalities with effort. Of the 13 patients with an inferior infarct, 11 had apparently normal wall motion in the modified left anterior oblique projection at rest, including 2 who manifested segmental wall motion abnormalities with submaximal exercise; the 2 remaining patients had wall motion abnormalities at rest that, on exercise, became more marked in one and were unchanged in one. Four of the 13 had a positive electrocardiographic response with exercise (one was taking digoxin); only one of these had a detectably more severe wall motion abnormality with exercise. Of the six patients with a nontransmural infarct, four had no identifiable wall motion abnormalities at rest; in one of these, an abnormality developed with exercise. The remaining two patients had wall motion abnormalities at rest; in one, a positive electrocardiographic ischemic response developed with exercise. Patients with an anterior infarct appear to have a different functional ventricular response to submaximal exercise at the time of hospital discharge than patients with an inferior or nontransmural Infarct. To identify ischemic responses with submaximal exercise in these patients one should ideally use both electrocardiographic monitoring and dynamic myocardial scintlgraphy.

Pre- and postoperative rest and exercise hemodynamics in children with pulmonary stenosis.

Twenty children with pulmonary valvular stenosis were studied by cardiac catheterization both at rest and during submaximal supine exercise, prior to and following pulmonary valvotomy. The resting and exercise states were comparable preoperatively and postoperatively since cardiac output, heart rate, A - V O 2 difference and oxygen consumption were similar. Evidence of improved cardiac function was found postoperatively. Both the rest and the exercise right ventricular end-diastolic pressure (RVEDP) decreased significantly following pulmonary valvotomy. Preoperatively, 12 of 20 patients showed an increase in RVEDP with exercise; in six of these there was a simultaneous fall in stroke index, indicating impaired myocardial function. No patient showed this response postoperatively. This indicates that although altered cardiac function can be demonstrated in some children with pulmonary valvular stenosis, it is reversible by pulmonary valvotomy. This is in contrast to studies in adults, and suggests that a factor in the natural history of pulmonary valvular stenosis is the impact of chronically elevated afterload on the right ventricle. Hemodynamic measurements made during exercise provide a useful means of assessing patients with pulmonary stenosis before and after pulmonary valvotomy.

Pulmonary intravascular and extravascular fluid volumes in exercising cardiac patients.

Pulmonary extravascular (PEW) and intravascular (PBV) fluid volumes were measured during cardiac catheterization by a multiple indicator-dilution technique in 21 cardiac patients at rest and during exercise. Increased PEW at rest was clearly related to increased left atrial and pulmonary artery pressures but not to blood flow or pulmonary vascular resistance. Submaximal supine exercise produced increased intracardiac pressures and flow, with PEW and PBV significantly increased in most cases and stable in a few. Transudation at higher pulmonary capillary pressures and increased capillary recruitment were proposed to explain the increases in PEW during this short-term stress. wo patients developed overt pulmonary edema with rales during exercise. These individuals are discussed separately.

Left atrial pressure during exercise in hemodynamic normals

Mean left atrial pressure during supine submaximal exercise was studied in seven hemodynamic normal individuals. A rapid increase in pressure to a maximum at the second to fourth minute of exercise followed by a slow decline to levels near or below those of rest conditions was noted in all individuals. A possible mechanism relating left ventricular exercise response to left atrial pressure is discussed.