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Cardiac dimensions and myocardial function of infants with congenital hypothyroidism. An echocardiographic study
Insights
Congenital hypothyroidism in infants significantly impacts cardiac function, leading to smaller heart dimensions and reduced cardiac output. However, left ventricular shortening velocity remains normal, despite prolonged pre-ejection periods.
Area of Science:
- Pediatric Cardiology
- Neonatal Endocrinology
- Echocardiography
Background:
- Congenital hypothyroidism (CH) is a condition affecting newborns, potentially leading to developmental issues.
- Cardiac function can be affected by thyroid hormone levels, but data in CH infants is limited.
Purpose of the Study:
- To assess cardiac dimensions and myocardial function in infants with congenital hypothyroidism using echocardiography.
- To compare cardiac parameters in hypothyroid infants with a healthy control group.
Main Methods:
- Echocardiography was performed on 12 infants diagnosed with congenital hypothyroidism.
- Cardiac measurements including ventricular dimensions, volumes, and functional indices were analyzed.
- Data was compared to 25 age-matched healthy infants.
Main Results:
- Hypothyroid infants exhibited significantly smaller left ventricular dimensions and volumes compared to controls.
- Reduced heart rate and cardiac output were observed in the hypothyroid group.
- While shortening fraction was normal, the pre-ejection period (PEP) and PEP/ejection time (ET) ratio were prolonged, suggesting diastolic dysfunction.
Conclusions:
- Congenital hypothyroidism is associated with impaired cardiac growth and reduced cardiac output in infants.
- Prolonged PEP/ET ratio indicates potential diastolic dysfunction, possibly linked to decreased preload.
Abstract:
This study was undertaken to evaluate the cardiac dimensions and various indices of myocardial function, determined by echocardiography, in a group of 12 infants with congenital hypothyroidism. Left ventricular systolic and diastolic dimensions, posterior wall thickness, enddiastolic and systolic volumes were all significantly lower in the hypothyroid infants compared with 25 normal infants of the same age. No pericardial effusion was found. Hypothyroid infant had a lower heart rate with a reduced cardiac output. The mean velocity of circumferential fibre shortening and the shortening fraction of the left ventricle were normal. The pre-ejection period of the left ventricle (PEP), however, was abnormally prolonged as well as the ratio PEP over left ventricular ejection time (PEP/ET). This ratio correlated inversely with the end-diastolic volume, suggesting that the increased PEP/ET could be partly the result of decreased preload.