Natural history of ventricular septal defect

20 per cent are living with a closed defect by 30, and 24 per cent by 6o years, both figures being a little better than those for persistent ductus. Closures occur mainly, but not exclusively, with small defects and normal pulmonary arterial pressures. This group, which forms nearly one-third of the total, has now an almost normal life expectation since treatment should eliminate the risk of dying from bacterial endocarditis. The expectation of life for those with larger defects has been calculatedfrom 25 deaths among 117 patients followed for 758 patient years. The mortality rate is high in the first two decades (2.2 and 2.9% per annum) and double the latter rate in the fourth and later decades. Of those with larger defects, the calculated deaths are nearly 40 per cent during the first two decades and nearly 8o per cent at the end of thefourth decade. They are the onlyfindings that can be compared with the age at death of reported necropsies. The latter are about IO per cent worse at the end of each of the first four decades and have a mean age at death of 23 years compared with the calculated 27 years. Both these findings are worse than for the other cardiac malformations that have been discussed. For all degrees of ventricular septal defect combined, the findings are of course better. Thus