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 cm(2) [SD])and minimum area (15.3 +/- 8.4 to 12.0 +/- 6.1 m(2)) 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/cm(2)) and afterload (effective arterial elastance, 17.9 +/- 11.6 to 26.3 +/- 16.4 mm Hg/cm(2)) were increased, and the end-systolic area associated with 100 mm Hg was reduced (18.3 +/- 10.0 to 13.7 +/- 5.8 cm(2)).

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.