PRONUS-ANGINA (ANGINA-PECTORIS INDUCED BY STOOPING OR CROUCHING) - A PROPOSED MECHANISM

Patients with severe coronary artery disease (CAD) sometimes complain of chest pressure upon crouching or bending-forward (pronus angina). T he factors that trigger pronus angina are not clear. We therefore inve stigated 28 patients with CAD and 26 normal subjects in the sitting, k nee-chest, stooping, and squatting positions. Systolic and diastolic b lood pressures were found to increase by 13.5 and 19.5 percent (p<0.00 5) in the stooping position. In addition, left ventricular (LV) ejecti on time index (LVETI) also increased (p<0.005). Despite the acute rise in aortic pressure, which is expected to lengthen the pre-ejection pe riod index (PEPI), the latter shortened slightly in 10 of 14 (71 perce nt) patients tested, suggesting augmentation in contractile force duri ng the isovolumic phase. Finally, left atrial size increased (P<0.005) during the knee-chest maneuver, suggesting that the LV size also incr eases upon bending forward. The effect of stooping on blood pressure w as similar in magnitude to that of squatting. It is concluded that the triggering factor for ''pronus angina'' in severe CAD may be explaine d as a combination of hemodynamic events which acutely increase myocar dial oxygen requirements.