Hemodynamic effects of synchronous high-frequency jet ventilation in mitral regurgitation

Hemodynamic effects of synchronous high-frequency jet venti-lation in mitral regurgitation. J. Appl. Physiol. 69(6): 2120-2125, 1990.-We tested the hypothesis that increases in intra-thoracic pressure (ITP), by decreasing the pressure gradient for anterograde left ventricular (LV) ejection, should augment cardiac output in acute mitral regurgitation (MR). In a pento-barbital-anesthetized closed-chest canine model, LV stroke vol-ume (SL & was measured by integration from an aortic flow probe signal. MR was induced by a regurgitant ring. ITP was elevated over apnea by means of intermittent positive-pressure ventilation (IPPV), asynchronous (asynch) high-frequency jet ventilation (HFJV), and cardiac cycle-specific (synch) HFJV. IPPV resulted in the greatest increase in ITP. MR caused a fall in SVLV and a rise in LV filling pressure that were not altered by IPPV. Compared with IPPV or apnea, both async