Pansystolic murmurs in supracristal ventricular septal defects indicate larger left-to-right shunt ratios (17% vs 7-9%) and more frequent large aortic valve prolapse (45% vs 9%).
What are the phonocardiographic features of the murmur in cases of supracristal ventricular septal defect and how do they relate to shunt ratio and aortic valve dynamics?
In supracristal VSD, the shunt ratio and dynamic behavior of the aortic valve significantly influence the pattern of the systolic murmur.
To clarify the phonocardiographic features of the murmur in cases of supracristal ventricular septal defect (VSD), we compared phonocardiograms with échocardiographie findings and data obtained by cardiac catheterization in 37 consecutive patients. The configurations of the systolic murmur were classified into three types: pansystolic murmur in 22 (59%), murmur with late systolic accentuation in 11 (30%) and early systolic murmur in 4 (11%). The shunt ratio from left to right in the group with pansystolic murmur was significantly larger than those in the other two groups (17 ± 10 vs. 9 ± 10 and 7 ± 8%, means ± SD, p < 0.05). Aortic valve prolapse was significantly less frequent in the group with early systolic murmur than in the other two groups (0 vs. 68 and 64%, p < 0.05). Large aortic valve prolapse, in which the valve lost its mobility because of complete herniation of the valve into the defect, was more frequent in the group with pansystolic murmur than in that with late systolic accentuation (45 vs. 9%, p < 0.05). In 3 of 4 patients with early systolic murmur, the flow across the defect, recorded by continuous-wave Doppler echocardiography, was interrupted in mid-systole and showed a similar pattern to that of the murmur recorded by phonocardiography. On the other hand, it continued until the second heart sound in the other two groups. We conclude that the shunt ratio and dynamic behavior of the aortic valve have important effects on the characteristics of the pattern of systolic murmur in cases of supracristal VSD.
Mori et al. (2017) studied this question. Pansystolic murmurs in supracristal ventricular septal defects indicate larger left-to-right shunt ratios (17% vs 7-9%) and more frequent large aortic valve prolapse (45% vs 9%).