Acute volume reduction with aortic valve replacement immediately improves ventricular mechanics in patients with aortic regurgitation

Objectives: Few data have been available regarding the immediate response in ventricular mechanics to acute volume reduction caused by aortic valve replacement for aortic regurgitation. Methods: We studied 9 patients in the operating room immediately before and after the institution of cardiopulmonary bypass. Left ventricular pressure and cross-sectional area (a surrogate of left ventricular volume) were measured with a catheter-tip manometer and a transesophageal echocardiographic system equipped with automated border-detection technology. Left ventricular pressure-area loops were constructed, and the caval occlusion method was used to obtain the slope of the end-systolic pressure-area relationship and the end-systolic area associated with 100 mm Hg. From the steady-state beats, stroke area was obtained by subtracting the minimum area from the maximum area. Effective arterial elastance, a measure of ventricular afterload, was calculated from end-systolic pressure, and stroke area as follows: effective arterial elastance equals end-systolic pressure divided by stroke area. Results: Reductions in maximum area (21.0 ± 8.5 to 16.0 ± 6.8 cm² [SD])and minimum area (15.3 ± 8.4 to 12.0 ± 6.1 m²) shifted the baseline pressure-area loops to the left. The slope of the end-systolic pressure-area relationship (11.6 ± 4.8 to 16.0 ± 7.5 mm Hg/cm²) and afterload (effective arterial elastance, 17.9 ± 11.6 to 26.3 ± 16.4 mm Hg/cm²) were increased, and the end-systolic area associated with 100 mm Hg was reduced (18.3 ± 10.0 to 13.7 ± 5.8 cm²). Conclusion: Correction of volume overload reduced preload (minimum area), shifted the end-systolic pressure-area relationship to the left (decreased end-systolic area), and improved ventricular contractility (increased slope of the end-systolic pressure-area relationship). The result indicated that acute volume reduction favorably influenced ventricular mechanical parameters immediately after the operation.