Biventricular function in exercise during autonomic (thoracic epidural) block

Abstract

Background: Blockade of cardiac sympathetic fibers by thoracic epidural anesthesia (TEA) was previously shown to reduce right and left ventricular systolic function and effective pulmonary arterial elastance. At conditions of constant paced heart rate, cardiac output and systemic hemodynamics were unchanged. In this study, we further investigated the effect of cardiac sympathicolysis during physical stress and increased oxygen demand.

Methods: In a cross-over design, 12 patients scheduled to undergo thoracic surgery performed dynamic ergometric exercise tests with and without TEA. Hemodynamics were monitored and biventricular function was measured by transthoracic two-dimensional and M-mode echocardiography, pulsed wave Doppler and tissue Doppler imaging.

Results: TEA attenuated systolic RV function (TV S': - 21%, P < 0.001) and LV function (MV S': - 14%, P = 0.025), but biventricular diastolic function was not affected. HR (- 11%, P < 0.001), SVI (- 15%, P = 0.006), CI (- 21%, P < 0.001) and MAP (- 12%, P < 0.001) were decreased during TEA, but SVR was not affected. Exercise resulted in significant augmentation of systolic and diastolic biventricular function. During exercise HR, SVI, CI and MAP increased (respectively, + 86%, + 19%, + 124% and + 17%, all P < 0.001), whereas SVR decreased (- 49%, P < 0.001). No significant interactions between exercise and TEA were found, except for RPP (P = 0.024) and MV E DT (P = 0.035).

Conclusion: Cardiac sympathetic blockade by TEA reduced LV and RV systolic function but did not significantly blunt exercise-induced increases in LV and RV function. These data indicate that additional mechanisms besides those controlled by the cardiac sympathetic nervous system are involved in the regulation of cardiac function during dynamic exercise. Trial registration Clinical trial registration: Nederlands Trial Register, NTR 4880 http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=4880 .

Keywords: Anesthesia; Autonomic; Circulation; Epidural; Exercise; Nervous system; Ventricular function, left; Ventricular function, right.

Fig. 1

Measurement protocol executed during both test periods (Control and TEA). Hemodynamic and echocardiographic measurements were performed during different measurement stages: pre (pre-study), immediately before epidural injection of ropivacaine 0.75%/ NaCl 0.9%; T0, 30 min after epidural injection of ropivacaine 0.75%/ NaCl 0.9%; T1, after 3 min bicycling with 20% of maximal workload; T2, after 3 min bicycling with 40% of maximal workload; T3, after 3 min bicycling with 60% of maximal workload; post (post-study), after 10 min recovery of exercise test. TTE transthoracic echocardiography, HR heart rate, CI cardiac index, SV stroke volume, MAP mean arterial pressure, SBP systolic blood pressure, DBP diastolic blood pressure

Fig. 2

Individual and mean (SD) hemodynamic values at different measurement stages (measurement stages, see Fig. 1). Spaghetti plot of individual heart rates at control condition (a) and TEA (b); mean values of HR (c), MAP (d), SVI (e), CI (f), SBP (g), SVR (h) and RPP (i) during control (blue symbols) and TEA (red symbols). P values are presented for the overall effects of thoracic epidural anesthesia (TEA), exercise (EXC) and interaction effects between exercise and TEA (INT). In case of significant overall effects, the specific time points (T0–T3) at which significance was reached are indicated with * for a significant TEA effect and † for a significant TEA–exercise interaction effect. CON control, HR heart rate, SVI stroke volume index, CI cardiac index, SBP systolic blood pressure, SVR systemic vascular resistance, RPP rate pressure product

Fig. 3

Individual and mean (SD) echocardiographic values for left ventricular function at different measurement stages (measurement stages, see Fig. 1). a Spaghetti plot of individual MV Sʹ values at control condition (a) and TEA (b); mean values of MV Sʹ (c), MV E (d), MV Eʹ (e) and MV E/Eʹ (F) during control (blue symbols) and TEA (red symbols). P values are presented for the overall effects of thoracic epidural anesthesia (TEA), exercise (EXC) and interaction effects between exercise and TEA (INT). In case of significant overall effects, the specific time points (T0-T3) at which significance was reached are indicated with * for a significant TEA effect and † for a significant TEA–exercise interaction effect. CON control, MV Sʹ peak systolic velocity of the mitral annulus, MV E peak mitral flow velocity during early filling phase, MV Eʹ early diastolic velocity of the mitral annulus, MV E/Eʹ ratio E to Eʹ

Fig. 4

Individual and mean (SD) echocardiographic values for right ventricular function at different measurement stages (measurement stages, see Fig. 1). a Spaghetti plot of individual TV Sʹ values at control condition (a) and TEA (b); mean values of TV Sʹ (c), TV E (d), TV Eʹ (e) and TV E/Eʹ (f) during control (blue symbols) and TEA (red symbols). P values are presented for the overall effects of thoracic epidural anesthesia (TEA), exercise (EXC) and interaction effects between exercise and TEA (INT). In case of significant overall effects, the specific time points (T0-T3) at which significance was reached are indicated with * for a significant TEA effect and † for a significant TEA-exercise interaction effect. CON control, TV Sʹ peak systolic velocity of the tricuspid annulus, TV E peak tricuspid flow velocity during early filling phase, TV Eʹ early diastolic velocity of the tricuspid annulus, TV E/Eʹ ratio E to Eʹ