A Hemodynamic Study on the Influence of the Right Ventricular Volume: Overload Upon Left Ventricle Function Pre and Post Operative Left Ventricular Function in Atrial Septal Defect

ABSTRACT

This study was done to investigate the effect volume overloading of right ventricle(RV) on the left ventricular(LV) volume and function in patients with isolated secundum type atrial septal defect(ASD) and to determine the hemodynamic indices affecting the postoperative reduction of RV size. Pre and postoperative echocardiogram and equilibrium radionuclide cardiac angiogram were analyzed in 39 patients of isolated secundum type ASD, who had their diagnosis confirmed by right heart catheterization and were operated at Seoul National University Hospital from January 1982 to July 1984. The ratio fo RV end-diastolic dimension to LV end-diastolic dimension(RVED/LVED), ratio of LV pre-ejection period and LV ejection time(PEP/LVET), ejection fraction(E.F.), fractional shortening(F.S.) mean velocity of circumferential fiber shortening(mVcf), peak ejection rate(PER) and peak filling rate(PFR) were measured in 24 normal control subjects and 39 patients with ASD before and after operation. The results obtained were as follows 1) The postop. reduction of RV size could be correlated with age at operation, but showed no correlation with the degree of QP/Qs, main pulmonary arterial systolic, diastolic, mean pressure, RVEDP and previous RV size. 2) The ratio of postop. RVED/LVED(0.58+/-0.15) was significantly decreased, compared with the ratio of preop(0.96+/-0.28)(P0.1). 4) There was no significant difference in LV systolic contractile functional indices between ASD group and normal control subjects and between pre and postop. status of ASD patients LVEF was 63.5+/-6.1(%) in preop., 63.0+/-5.7(%) in postop and 62.4+/-6.6(%) in normal control subjects. F.S. was 27.3+/-5.7(%) in preop., 28.2+/-3.1(%) in postop. and 28.7+/-4.5(%) in normal control subjects. mVcf was 0.81+/-0.11(Cire/sec) in preop., 0.80+/-0.10(Circ/sec) in postop. and 0.82+/-0.14(Circ/sec) in normal control subjects. PER was 2.82+/-0.61(EDV/sec) in preop., 2.84+/-0.56(EDV/sec) in postop. and 2.84+/-0.45(EDV/sec) in normal control subjects. 5) The postop. PFR 3.34+/-0.46(EDV/sec) was significantly increased, compared with preop. PFR 2.51+/-0.46(EDV/sec)(P0.1). 6) The postop. RVEF(51.4+/-6.3%) was significantly decreased, compared with preop. RVEF(54.5+/-9.9%)(P<0.005). Pre and postop. RVEF of ASD patient were significantly lower than RVEF of normal control group(60.3+/-3.1%)(P<0.01, P<0.005). The results indicate that postop. reduction of RV size could be correlated with age at operation. The effect of RV volume overloading on LV could not change systolic contractile functional indices, but diastolic filling index. There is many evidences suggesting that RV filling influences LV diastolic function which are occured by means of left ward shift of the interventricular septum and indirectly by linkage of filling of the two ventricules by common enclosure in the pericardium(underfilled LV volume and decreased LV compliance). Mildly diminished overall LV performance as shown by systolic time intervals appears to be related to the volume overload of the RV and to the concomitantly diminished volume of LV rather than to any myocardial contractility. LV systolic time inverval was non-invasive and sensitive index in assessing overall LV performance independent to LV geometric configuration and abnormal motion of regional ventricular wall.