Key result
Rapid cardiac pacing in swine reduces total arterial compliance ~36% and lowers stroke volume.
Why the study?
The differential effects of rapid cardiac pacing on small and large vessels have not been well established.
Does pacing-induced acute tachycardia alter systemic hemodynamics and arterial stiffness in domestic swine?
Does pacing-induced acute tachycardia alter systemic hemodynamics and arterial stiffness in domestic swine?
Acute tachycardia up to 135 bpm causes a mismatch in the response of the aorta and small arteries, reducing total arterial compliance despite increasing aortic distensibility.
Acute tachycardia may reduce arterial compliance independently of aortic distensibility; hypothesis-generating in swine, leaves open human translation.
Background: The differential effects of rapid cardiac pacing on small and large vessels have not been well established. The objective of this study was to investigate the effect of pacing-induced acute tachycardia on systemic hemodynamics and arterial stiffness. Methods: The pressure and flow waves in ascending aorta and femoral artery of six domestic swine were recorded simultaneously at baseline and heart rates (HR) of 135 and 155 beats per minutes (bpm) for determination of the total arterial compliance. Accordingly, the flow waves were simultaneously measured at carotid and femoral arteries to quantify the aortic pulse wave velocity (PWV). The arterial distensibility was identified in small branches of coronary, carotid and femoral arteries with diameters of 300-600 μm by ex vivo experiments. Results: The rapid pacing in HR up to 135 bpm reduced the total arterial compliance, SV, systemic PP, and central systolic pressure by 36±17%, 38±26%, 29±16%, and 23±12%, respectively, despite no statistical difference of mean aortic pressure (MAP), cardiac output (CO) and peripheral resistance. The pacing also resulted in a decrease of distensibility of small muscular arteries, but an increase of aortic distensibility. Pacing from 135 to 155 bpm had no effect on systemic hemodynamics and arterial stiffness. Conclusions: There is an acute mismatch in the response of aorta and small arteries to pacing from basal HR to 135 bpm, which may have important pathological implications under chronic tachycardia conditions.
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Huo et al. (2018) studied Acute tachycardia (n=12). Rapid cardiac pacing vs. Baseline heart rate (80-105 bpm) was evaluated on Total arterial compliance (ml/mmHg) (p=0.009). Rapid cardiac pacing up to 135 bpm in swine significantly reduced total arterial compliance by 36% and stroke volume by 38%, while increasing aortic distensibility.
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