Hemodynamic effects of dynamic exercise in children and adolescents with moderate-to-small ventricular septal defects.

We studied the hemodynamic effects of dynamic exercise during cardiac catheterization in 35 children and adolescents with small-to-moderate ventricular septal defects. Eighteen of them exercised at 25% and 50% of their maximum workload and 17 exercised at 60%. There was no significant difference between the two groups with respect to age and body mass, height, and surface area. The changes evoked by exercise showed the same pattern at the different workloads, although they were more marked at the higher than at the lower percentage of maximum workload. During exercise the pulmonary vascular resistance did not change, in contrast to the systemic vascular resistance, which decreased. The pulmonary and systemic blood flows both increased, while the left-to-right shunt flow did not change, which led to a decrease of the left-to-right shunt fraction. As the heart rate increased and the shunt flow did not change, the shunt volume per beat decreased during exercise. We conclude that in patients with small-to-moderate ventricular septal defects the hemodynamic effects of dynamic exercise are favorable because the normal rise in systemic blood flow occurs without a corresponding increase in left-to-right shunt flow. Consequently, children and adolescents with such defects should not be restricted in their dynamic exercise activities.

Anatomic and functional "obstruction" of the outflow tract in atrioventricular septal defects with separate valve orifices ("ostium primum atrial septal defect"): an echocardiographic study.

Left ventricular (LV) outflow tract (OT) obstruction can be treacherous in any form of atrioventricular (AV) septal defect. The properties of the LVOT were investigated echocardiographically in 64 patients with separate valve orifices ("ostium primum atrial septal defect") who had survived corrective surgery. M-mode and cross-sectional echocardiographic (echo) images were made of the LVOT. The degree of malalignment of the aorta with the ventricular septum, the left atrium-aortic ratio, the fractional LV shortening and the diameter of the LVOT were recorded. Fixed anatomical obstruction was found in 3 patients, consisting of muscular bands or abnormal attachment of tension apparatus. Malalignment of the aorta with the ventricular septum was found in 62% of the patients. The diameter of the LVOT was smaller than that of the aortic root in 71% of the cases. The mean diameter of the LVOT was 92 +/- 27% (range 35 to 143%) of the aortic root diameter. Because its walls are mainly muscular, the LVOT constricts during systole. The mean end-systolic diameter of the LVOT was 77 +/- 22% (range 23 to 129%) of the aortic root diameter. Sequential measurements showed that the LVOT constricted gradually, but the velocity of constriction in patients with the most severe narrowing showed a distinct maximum in the first fifth of systole. In conclusion, a series of elements contribute to a potentially perilous arrangement of the LVOT in patients with AV septal defect. This intrinsically narrow tunnel was constricted during systole by its muscular walls.(ABSTRACT TRUNCATED AT 250 WORDS)

Value of systolic time intervals in assessing severity of congenital aortic stenosis in children.

Simultaneous recordings have been made of electrocardiogram, phonocardiogram, carotid pulse tracing, left ventricular pressure, and aortic pressure in 27 children with aortic valve stenosis and 3 children with membranous subaortic stenosis. Peak systolic pressure difference ranged from 10 to 110 mmHg (1.3 to 14.6 kPa). None of the patients had congestive heart failure and cardiac output was in the normal range in all. Total electromechanical systole, left ventricular ejection time, and pre-ejection time were corrected for heart rate, age, and sex. Mild stenosis (peak systolic pressure difference less than or equal to 50 mmHg (6.7 kPa)) was present in 18, severe stenosis (peak systolic pressure difference greater than 50 mmHg) in 12 patients. The externally measured pre-ejection time and ejection time proved to be nearly equal to the corresponding intervals measured internally; from these data it is concluded that pre-ejection time and ejection time in children with aortic stenosis can be measured reliably by non-invasive methods. Mean values for corrected total electromechanical systole and ejection time were prolonged, but the corrected pre-ejection time did not differ from the normal value. When corrected time intervals were plotted against severity of the aortic stenosis as expressed by the peak systolic pressure difference or the aortic valve orifice index, a wide scatter was found. It is concluded that a normal ejection time is strong evidence against a peak systolic pressure difference of more than 50 mmHg (6.7 kPa) or an aortic valve orifice index less than 0.70 cm2 per m2 BSA. A prolonged ejection time, however, may occur in mild as well as in severe stenosis. Total electromechanical systole and pre-ejection time have no value in predicting the severity of aortic stenosis in children.