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Coronary arteries in the hypoplastic left heart syndrome. Histopathologic and histometrical studies and implications
U Sauer1, A C Gittenberger-de Groot, M Geishauser
1Kinderkardiologie, Deutsches Herzzentrum, FRG.
Insights
Hypoplastic left heart syndrome with mitral stenosis is linked to coronary artery pathology, specifically thickened left coronary arteries. These changes suggest potential ventricle-coronary artery communications in affected infants.
Area of Science:
- Pediatric Cardiology
- Congenital Heart Disease
- Vascular Pathology
Background:
- Hypoplastic left heart syndrome (HLHS) encompasses a spectrum of congenital heart defects.
- The role of mitral valve patency and left ventricular endocardial fibroelastosis (EFE) in coronary artery (CA) pathology in HLHS is not fully understood.
Purpose of the Study:
- To investigate subepicardial coronary artery pathology in HLHS.
- To determine if CA pathology correlates with mitral valve status and left ventricular endocardial fibroelastosis.
Main Methods:
- Comparative histological and histometrical analysis of coronary arteries from HLHS specimens (aortic/mitral atresia vs. aortic atresia/mitral stenosis) and normal hearts.
- Measurement of arterial size and wall thickness at six standardized sites.
Main Results:
- Coronary arteries were macroscopically normal in aortic/mitral atresia, with left dominance.
- In contrast, hearts with aortic atresia and mitral stenosis showed thicker, tortuous coronary arteries, primarily affecting the left coronary arteries.
- Histometry revealed increased medial thickness and relative wall thickening in the left coronary arteries of the mitral stenosis group, suggesting ventricle-coronary artery communications.
Conclusions:
- Mitral valve stenosis in HLHS is associated with significant coronary artery wall thickening.
- These findings highlight a potential link between left ventricular endocardial fibroelastosis, mitral valve obstruction, and coronary artery abnormalities in HLHS.
Abstract:
The subepicardial coronary arteries (CAs) in the hypoplastic left heart syndrome (HLHS) were studied for pathology dependent on the patency of the mitral valve and the presence of endocardial fibroelastosis (EFE) of the left ventricle (LV). Nine heart specimens with aortic and mitral atresia (group 1) were studied and compared with 19 hearts with aortic atresia and mitral stenosis (group 2) (EFE of the LV was present in all cases) and 10 normal hearts. The median age at death was 3 days. For the histological and histometrical studies, 5-mm blocks from six comparable sites of the left (L) and right (R) CAs were serially sectioned and routinely processed. The arterial size and wall thickness were measured. Macroscopically, the CAs in group 1 were normal except for the prevalence of left dominance (56%). In contrast in group 2, the CAs were thicker and tortuous. Histopathology was restricted almost exclusively to group 2 specimens (11 of 19), with the proximal LCAs being the most affected. However, eight hearts with EFE in group 2 had no structural wall changes of the CAs. Histometrically, the sizes (external diameters) of the LCAs and RCAs were similar (0.5-1.0 mm) in groups 1 and 2 and in the normal group; however, we noted an increase in percent medial thickness in group 2 specimens, especially of the LCAs. Furthermore, in some group 2 hearts, the wall thickness (intima and media) relative to the luminal size (internal radius) of proximal and middle LCAs was significantly increased, suggesting the presence of ventricle-CA communications.(ABSTRACT TRUNCATED AT 250 WORDS)