Hisae Hayashi

Assessment of left ventricular function before and after Fontan's operation for the correction of tricuspid atresia

SummaryFunctional change in the left ventricle was studied in the light of changes in the left ventricular (LV) volume preload before and after Fontans operation. Six cases with tricuspid atresia (TA) were studied, and they had either types Ib or IIb. The preoperative LV end-diastolic volume index (LVEDVI) was 123±44 ml/m2, which corresponds to 166%±45% of normal values. This suggests that in TA the preload of the LV volume is increased because of its peculiar hemodynamic situation. After Fontans operation, the LVEDV decreased by 24.6% to 119.6±87.7 ml (P=0.01), which corresponds to 120%±50.9% of normal values. Presenting a striking contrast to the decrease in LVEDV, the postoperative reduction in LV end-systolic volume (LVESV) was approximately 8%. Preoperative and postoperative values for LVESV were 67.1±50.8 ml and 62±45.6 ml, thus, the systolic volume was decreased. Because of the small change in LVESV, the ejection fraction (EF) of the left ventricle significantly decreased from 0.61±0.1 preoperatively to 0.48±0.1 postoperatively. The cardiac index (CI) remained in the range of 1.9–2.5 1/min/m2 with a mean of 2.2±0.2 1/min/m2 at 1 month after operation. But, later, improvement in EF was observed in one case, in which the CI increased from 2.5 to 3.2 1/min/m2. In cases with TA in which function of the left ventricle is damaged by chronic LV volume overload and longstanding hypoxemia, important factors for long-term survival after Fontans operation are the degree of postoperative improvement in LV function and the maximal limit of LV function, which could be affected by compromised function of the right heart.

Measurement of severity of aortic stenosis experimentally produced in dogs without inserting a catheter into the left ventricle.

When flow passes through an orifice, pressure loss does not occur in the laminar core of the jet distal to the stenosis, but occurs in the region more distal to the stenosis, where the laminar core disappears and turbulence develops. Therefore, if total pressure is measured in the laminar core of the jet some distance downstream of a stenotic aortic valve, it should be equal to total pressure on the left ventricular side of the aortic valve. An experimental study was performed in 5 dogs to test this hypothesis. The results revealed that left ventricular pressure during the ejection period can be determined by measuring the pressure in the laminar core. A preliminary evaluation of the clinical applicability of our method was performed during catheterization in a patient with severe aortic valve stenosis. In this case, the pressure obtained in the jet downstream of the aortic valve was slightly lower than that obtained in the left ventricle.