ABNORMAL CAPILLARY MORPHOLOGY IN CONGENITAL HEART DISEASE

Abstract

Capillary morphology has been studied in 111 normal children. In 98% of these cases, straight hairpin forms make up over 80% of the capillaries examined. Thirty children with congenital heart disease showed 80% abnormal capillary patterns consisting of dilated, tortuous, and branched loops. These were most marked in cyanotic tetralogy of Fallot and ventricular septal defect with pulmonary hypertension. These cases also were associated with microscopic hemorrhages, increased capillary fragility and actual postoperative hemorrhagic complications. Definitive surgery in two cases, though improving the patient, did not result in changes in the abnormal capillary patterns. It is suggested that the role of the capillary structure in rheology of blood in the microvasculature has largely been ignored and that abnormalities in this vascular compartment may affect perfusion of tissues. The association of abnormalities in coagulation studies, hemorrhage, and thrombosis with congenital heart disease may in part be related to the morphologic vascular abnormalities. The abnormal capillary findings may be due to maturational arrest or dysmaturity of this portion of the cardiovascular system or may be the result of chronic hypoxia.