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Left ventricular wall stress and function in childhood coarctation of the aorta
Insights
Children with coarctation of the aorta show enhanced left ventricular ejection performance and reduced wall stress, similar to but less pronounced than aortic stenosis. This indicates a distinct pediatric response to pressure overload.
Area of Science:
- Pediatric Cardiology
- Cardiovascular Physiology
Background:
- Children with aortic stenosis display unique left ventricular adaptations to pressure overload.
- These adaptations include hypertrophy, enhanced ejection performance, and reduced wall stress.
Purpose of the Study:
- To investigate if similar left ventricular mechanical changes occur in children with coarctation of the aorta.
- To compare the response to pressure overload in coarctation versus aortic stenosis.
Main Methods:
- Left ventricular mechanics were assessed via catheterization in 14 children with coarctation of the aorta and 10 healthy controls.
- Key parameters measured included ejection fraction, velocity of circumferential fiber shortening, and end-systolic stress.
Main Results:
- Children with coarctation had significantly higher ejection fraction and velocity of circumferential fiber shortening than controls.
- End-systolic stress was significantly lower in children with coarctation compared to controls.
- A similar, though less pronounced, adaptive response was observed in coarctation compared to aortic stenosis.
Conclusions:
- Coarctation of the aorta in children induces distinct left ventricular adaptations.
- These adaptations involve enhanced ejection performance and diminished wall stress, mirroring but less severe than aortic stenosis.
- The findings highlight a unique pediatric response to left ventricular pressure overload.
Abstract:
Unlike most adults with compensated pressure overload of the left ventricle, children with moderate to severe aortic stenosis exhibit pronounced left ventricular muscle hypertrophy, enhanced ejection performance and diminished wall stress. To determine whether these findings are present in other forms of left ventricular pressure overload in children, left ventricular mechanics were studied by catheterization in 14 children with coarctation of the aorta (average peak gradient 39 +/- 17 mm Hg) and in 10 normal children. Ejection fraction and mean velocity of circumferential fiber shortening in the coarctation group (0.74 +/- 0.09 and 1.71 +/- 0.43 circumferences/s, respectively) were significantly higher than in normal subjects (0.65 +/- 0.05 and 1.27 +/- 0.26 circumferences/s, respectively) (p = 0.008), but the ranges for both groups overlapped. End-systolic stress in children with coarctation (77 +/- 20 dynes X 10(3)/cm2) was less than in normal children (121 +/- 24 dynes X 10(3)/cm2) (p less than 0.001), again with overlap of the ranges for both groups. The ratio of end-systolic stress to end-systolic volume index, an estimate of contractile function, was similar in both groups. Relations between severity of obstruction (left ventricular peak systolic pressure, coarctation gradient) and end-systolic stress and between stress and ejection performance were present within the coarctation group. Comparison of these data with those found in children with moderate to severe aortic stenosis shows a similar but less pronounced response to pressure overload due to coarctation of the aorta.