Intermittent disappearance of the murmur of patent ductus arteriosus.

T HE MURMUR of patent ductus arteriosus is usually considered to be stable, although it may be modified by certain pharmacologic agents.1 2 Absence of the typical duetus murmur has most commonly been ascribed to the presence of relative or absolute pulmonary hypertension;3 4-6 occasionally it is ascribed to heart failure,7 a very small duetus,1' 8 or spontaneous closure of the duetus.7' 9, 1 Spontaneous disappearanee and subsequent reappearance of the typical murmur of patent ductus unassociated with pulmonary hypertensioni, heart failure, polycythemia or other congenital anomalies has niot been previously documented to our knowledge. The purpose of this report is to describe this phenomenon and to attempt to explain it.