Left ventricle haemodynamics and vaso-active hormones during graded supine exercise in healthy male subjects

Abstract

Left ventricle systolic and diastolic functional parameters were measured by gated equilibrium radionuclide cardiography in 12 healthy men (age 33-51 years) at rest and during graded supine exercise. The leftventricle end-diastolic volume showed an initial small (11%) increase during low submaximal exercise [from mean 163 (SD 40) at rest to mean 181 (SD 48) ml], while left ventricle end-systolic volume decreased successively [from mean 59 (SD 19) to mean 39 (SD 21) ml] with increasing exercise. Stroke volume was therefore elevated at all exercise levels compared with rest [mean 104 (SD 23) ml], and the peak value [mean 128 (SD 33) ml] was found at the lowest exercise level, contributing 40% to the initial increase in cardiac output. Cardiac output increased from mean 6.2 (SD 1.4) at rest to mean 20.2 (SD 5.0) l.min-1 at maximum. Left ventricle peak ejection and peak filling rates increased from mean 449 (SD 89) and mean 442 (SD 85) ml.s-1 at rest to mean 996 (SD 227) and mean 1255 (SD 333) ml.s-1, respectively, at maximum. The myocardium oxygen consumption, assumed to be proportional to the sum of the stroke work and the potential energy, increased fourfold, but absolute values were twice as high as expected, indicating that extrapolation from data obtained in dog hearts (as we have done) cannot be directly applied to humans. Selected vaso-active hormones were measured at all exercise intensities. Noradrenaline (NA), adrenaline (A) and angiotensin II (AII) concentrations showed a very pronounced increase at maximal exercise compared with the preceding lower intensites, while atrial natriuretic factor (ANF) and cyclic guanosinemonophosphate (cGMP) concentrations showed a more continuous increase, and dopamine (DA) remained almost unchanged. This speaks in favour of a crucial role for NA, A and AII in preserving blood pressure at maximum exercise, while DA probably has no importance for the cardiovascular homeostasis during exercise. Increases in concentrations of ANF and cGMP were highly correlated (r = 0.86). Our data supported the opinion that there is a cardiac limitation to maximal performance connected to the cardiac pumping capacity.

Myocardial Response to Incremental Exercise in Endurance‐Trained Athletes: Influence of Heart Rate, Contractility and the Frank‐Starling Effect

“…However, the percentage change in SV from rest to maximum upright exercise was substantially larger than that observed during supine exercise. Investigators have shown that there are minor changes in SV during incremental exercise in the supine position in healthy individuals (Kanstrup et al 1995). The results from the present investigation indicate that the myocardium may approach its limits for ventricular filling during supine exercise.…”

“…These investigators commonly reported an initial increase in EDV followed by a sharp decline at maximal exercise. A consecutive decline in end-systolic volume has also been commonly observed during incremental exercise (Adams et al 1992;Kanstrup et al 1995). Others have reported maintenance of EDV throughout incremental exercise, with a concomitant reduction in end-systolic volume (Jensen-Urstad et al 1998).…”

Baseline left ventricular ejection fraction associated with symptom improvements in both children and adolescents with postural tachycardia syndrome under metoprolol therapy

“…[32][33][34][35] Moreover, previous studies have indicated that ventricular function indexes (LVEF, LVFS, or left ventricle volume) increased significantly during upright exercise in healthy humans (vs. the resting state) and that plasma catecholamine concentrations were positively correlated with LVEF changes or left ventricle volume. [36,37] However, the resting LVEF value decreased significantly after metoprolol treatment for coronary artery disease, [38] and children with vasovagal syncope experience symptom improvement after metoprolol treatment. [39] The above facts attracted us to design the present study to evaluate if LVEF might be associated with symptom improvement after metoprolol treatment for children and adolescents with POTS.…”

“…the resting state) and that plasma catecholamine concentrations were positively correlated with LVEF changes or left ventricle volume. [ 36 , 37 ] However, the resting LVEF value decreased significantly after metoprolol treatment for coronary artery disease, [ 38 ] and children with vasovagal syncope experience symptom improvement after metoprolol treatment. [ 39 ] The above facts attracted us to design the present study to evaluate if LVEF might be associated with symptom improvement after metoprolol treatment for children and adolescents with POTS.…”