Why the study?
Does increasing heart rate by atrial pacing improve cardiac output in healthy male individuals?
Does increasing heart rate by atrial pacing improve cardiac output in healthy male individuals?
Cardiac output during exercise is primarily regulated by peripheral vasodilatation rather than an increase in heart rate, as pacing-induced tachycardia is offset by decreased stroke volume.
Pacing to raise heart rate does not boost output in healthy males; leaves open effects in cardiovascular disease.
Key points During exercise, cardiac output is regulated to match oxygen delivery to the metabolic demand. This study evaluated the role of heart rate and peripheral vasodilation in the regulation of cardiac output during exercise. We increased heart rate by atrial pacing in 10 healthy male individuals during three different conditions: at rest, during exercise and during femoral arterial ATP infusion at rest. Increasing the heart rate by atrial pacing by up to 54 beats min −1 did not increase cardiac output in any of the three given conditions as there was a proportional decrease in stroke volume. These results indicate that cardiac output is regulated by changes in peripheral vasodilatation, whereas an increase in heart rate is less important.
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Bada et al. (2012) studied this question.
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