Placental barrier to coagulation factors: its relevance to the coagulation defect at birth and to haemorrhage in the newborn.

The placental barrier to coagulation factors was assessed by measuring their levels in maternal venous and neonatal umbilical arterial and venous blood and was found to be largely complete. Detailed coagulation assessments in a large number of term and premature neonates showed that term neonates had a mild coagulation deficiency at birth. Premature neonates had a more definite deficiency, which became more severe with increasing prematurity.

Heterograft aortic valve replacement: initial follow-up studies.

Twenty-three patients have had calf or pig heterograft aortic valve replacements. Eight of these patients have required Starr-Edwards mitral ball-valve prostheses for associated mitral valve disease. There have been two hospital deaths and one late death.