From the Research
Squatting actually decreases left ventricular (LV) preload by reducing venous return to the heart, as stated in the most recent and highest quality study 1. When a person rises from a squatting position, the decrease in preload and afterload augments dynamic left ventricular outflow tract obstruction. This is particularly relevant in the diagnosis and management of hypertrophic cardiomyopathy, where symptoms can be provoked or alleviated by changes in preload and afterload. Some key points to consider when evaluating the effect of squatting on LV preload include:
- The compression of veins in the lower extremities and abdomen during squatting pushes blood toward the heart, but rising from the squatting position has the opposite effect, decreasing central blood volume and right atrial pressure.
- The decreased preload reduces the volume of blood in the ventricle at the end of diastole, which can lead to decreased stroke volume and cardiac output.
- Squatting and rising can be used as a provocative maneuver to diagnose and assess the severity of left ventricular outflow tract obstruction in patients with hypertrophic cardiomyopathy, as seen in the case report 1. Other studies, such as 2, 3, 4, and 5, provide additional insights into the hemodynamic effects of squatting, but the most recent and highest quality study 1 takes precedence in guiding clinical decision-making. The clinical implications of these findings are significant, as they can inform the diagnosis and management of various cardiac conditions, including hypertrophic cardiomyopathy. By understanding the effects of squatting on LV preload, clinicians can better utilize this maneuver to assess and manage patients with cardiac disease.