A Clinical Study of Obstructing Subinfundibular Muscular Bundles of the Right Ventricle in Congenital Cardiovascular Anomalies

ABSTRACT

During the period of 4 years from May, 1981 to April, 1985, 71 cases of obstructing subinfundibular muscular bundles of the right ventricle in congential cardiovascular anomalies were diagnosed by cariac catheterization and angiography at Hanyang University. The finding of right ventricular angiogram and degree of the right ventricular outflow obstruction, clinical data, electrocardiographic data and hemodynamic data were correlated irrespectively. The summary of this article is as follows. 1) The age of patients was ranged from 1 to 22 years old with a mean age of 8 years old. There were 39 males and 32 females with MF ratio of 1.21. The incidence of obstructing subinfundibular muscular bundles of the right ventricle in congenital cardiovascular anomalies was higher with increasing age. 2) The associated cardic anomalies were as follows 40 cases (56%) of isolated ventricular septal defect(VSD), 13(18%) of tetralogy of Fallot physiology, 7(10%) of patent ductus arteriosus(PDA), 3(4%) of pulmonary stenosis, 1 aortic stenosis, 1 double outlet of right ventricle(DORV), 1 trilogy, 1 ostium secundum defect, etc. The incidence of VSD with or without other associated cardiovascular anomalies was 56 cases(79%) out of 71 cases. 3) Maximum systolic pressure gradient between proximal and distal chamber of the right ventricle were under 25 mmHg in 32 cases, between 25 and 50 mmHg in 13 and above 50 mmHg in 26. Pressure gradients of all 7 cases with PDA were under 25 mmHg. 4) Correlative assesment of angiographic manifestation(2 indiciesDiameter of right ventricular outflow tract(systolic phase)/diameter of tricuspid valvular annulus(diastolic phase)=OT/TV, Diameter of right ventricular outflow tract(systolic phase)/Length of right ventricular diaphragmatic surface(systolic phase)=OT/RV) according to pressure gradient, OT/Tv and OT/RV values were lower the increasing pressure gradient, between proximal and distal chamber of the right ventricle. These were reverse correlations but coefficients of correlation(r) were-0.49and -0.48. Therefore, the degree of right ventricular outflow obstruction could be predicted, using 2 indices of right ventricular angiogram in individual cases, but could not be calculated accurately. 5) This indicated that pressuer gradient was also affected by technical errors, variable cardic anomalies, development of sinusoid, age and the other factors. 6) We assumed that non-invasive Doppler echocardiography could be useful in making the diagnosis and follow up of the patient with obstructing subinfundibular muscle bundles in right ventricle.