Abstract 18285: Discordant Impact of Baroreflex Activation on Cardiac Output Between the Normal Heart and Failing Heart
Introduction: Baroreflex stabilizes arterial pressure (AP) through modulating sympathetic nervous activity (SNA). We previously reported that arterial changes in resistance and stressed blood volume predominantly contribute to the baroreflex control of AP (AHA 2013). It has been well established that cardiac output (CO) of the normal heart increases greatly with increases in preload, while hardly decreases with increases in afterload. The CO dependence of preload and afterload are opposite in the failing heart. Therefore it is conceivable that the impact of baroreflex activation on CO is discordant between the normal heart and failing heart.
Hypothesis: We hypothesized that baroreflex activation increases CO in the normal heart, while decreases CO in the failing heart.
Methods: We used 5 normal and 5 pacing induced heart failure dogs (ejection fraction of 20-30%). Under general anesthesia, we isolated both carotid sinuses and connected them to a servo-controlled piston pump to control intra-sinus pressure (CSP). We set CSP at 80mmHg to allow hemodynamics to reach steadystate. We then increased CSP to 160 mmHg to activate baroreflex and suppress SNA in both group. We measured right atrial pressure (RAP), left atrial pressure (LAP), mean AP and CO.
Results: In the normal heart, activation of baroreflex did not change LAP (5 ± 1 mmHg vs. 4 ± 1 mmHg, p=ns) or RAP (3 ± 1 mmHg vs. 3 ± 1 mmHg, p=ns) but markedly decreased AP (166 ± 21 mmHg vs. 89 ± 20 mmHg, p<0.0005) and CO (98 ± 15 ml/kg/min vs. 63 ± 16 ml/kg/min, p<0.001). In the failing heart, however, the activation of baroreflex significantly decreased LAP (23 ± 2 mmHg vs. 9 ± 4 mmHg, p<0.005) and increased CO (40 ± 10 ml/kg/min vs. 46 ± 10 ml/kg/min, p<0.005), while its impact on RAP (8 ± 2 mmHg vs. 6 ± 2 mmHg, p<0.005) and AP (93 ± 25 mmHg vs. 68 ± 18 mmHg, p<0.005) were moderate. In the presence of poor left ventricular function, baroreflex activation decreased congestion and increased CO.
Conclusions: Activation of baroreflex strikingly reduces LAP and increases CO in dogs with failing heart. The beneficial impacts result from the preload insensitivity and afterload sensitivity of CO in the failing heart. This mechanism may serve as a novel therapeutic strategy for decompensated heart failure.
Author Disclosures: T. Sakamoto: None. T. Kakino: None. K. Saku: None. K. Sakamoto: None. K. Hosokawa: None. K. Sunagawa: None.
- © 2014 by American Heart Association, Inc.