The influence of intermittent apnea on aortic hemodynamics in healthy young men

Background: Sleep apnea is known as a high-risk factor for cardiovascular disease (CVD); However, the influence of apnea on aortic blood pressure and augmentation index (AIx), which cardiac load and independent risks for a future CVD event, remains unclear. Therefore, this study aimed to examine the influence of intermittent normoxic apnea on aortic arterial hemodynamics in healthy men. Methods: Sixteen healthy young men (23 ± 1.6 years mean ± SD) underwent the repetitive 20-s apnea with a 40 s interval for 20 min. During the interval, each subject maintained a breath pace at 15 breaths/min. Central hemodynamics were evaluated every 5 min by pulse wave analysis from peripheral (radial) arterial pressure waveforms via general transfer function method and compared among three phases defined as “breath” (for 20 s before apnea), “apnea”, and “rebreathe” (for 20 s after apnea). The baseline values were calculated from the first breathing cycle and compared with each breathing phase every 5 min. Results: Aortic systolic blood pressure and AIx were significantly higher at rebreathe phase than the other phases. Likewise, heart rate and double product (aortic systolic blood pressure × heart rate) were significantly higher in rebreathe phase than the other phases. Conclusions: These results suggest that cardiac load is increased by intermittent normoxic apnea, especially during the rebreathing phase.