Squatting: the hemodynamic change is induced by enhanced aortic wave reflection.

BACKGROUND Although "squatting" in patients with tetralogy of Fallot is famous, the hemodynamic mechanism of the phenomenon has not been fully elucidated. To clarify the mechanism of squatting, the change in aortic pulsatile property induced by squatting was investigated. METHODS Twelve healthy young adults were enrolled in this study. The change in central pressure waveform induced by squatting was investigated using SphygmoCor (PWV Medical, Sydney, Australia). RESULTS The augmentation index during squatting was higher than that during standing (mean +/- SEM, 6.3 +/- 1.1 v 25.0 +/- 1.1; P <.0001). The heart rate corrected augmentation index during squatting was also higher than that during standing (7.9 +/- 0.9 v 25.6 +/- 1.0; P <.0001). CONCLUSION Squatting enhances the aortic wave reflection. It may cause a rise in aortic pressure and may improve cyanotic spells in patients with tetralogy of Fallot.