Impact of acute moderate elevation in left ventricular afterload on diastolic transmitral flow efficiency: analysis by vortex formation time.

ABSTRACT

BACKGROUND: The formation of a vortex alongside a diastolic jet signifies an efficient blood transport mechanism. Vortex formation time (VFT) is an index of the optimal conditions for vortex formation. It was hypothesized that left ventricular (LV) afterload impairs diastolic transmitral flow efficiency and therefore shifts the VFT out of its optimal range. METHODS: In 9 open-chest pigs, LV afterload was elevated by externally constricting the ascending aorta and increasing systolic blood pressure to 130% of baseline value for 3 minutes. RESULTS: Systolic LV function decreased, diastolic filling velocity increased only during the late (atrial) phase from 0.46 +/- 0.06 to 0.63 +/- 0.19 m/s (P = .0231), and end-diastolic LV volume and heart rate remained unchanged. VFT decreased from 4.09 +/- 0.27 to 2.78 +/- 1.03 (P = .0046). CONCLUSION: An acute, moderate elevation in LV afterload worsens conditions for diastolic vortex formation, suggesting impaired blood transport efficiency.