PERSISTENT DUCTUS ARTERIOSUS (PDA)

Normally, the ductus arteriousus functionally closes several hours after birth, and anatomically within 4 to 8 weeks.

In the presence of PDA, there is a continuous arteriovenous shunt between the aorta and pulmonary artery, the volume of which depends on the size of the ductus (50% of the LV output may be recirculated through the lungs-volume overload of LV and pulmonary congestion). Persistance of a large PDA can be complicated by pulmonary changes and Eisenmenger's physiology.

CLINICAL FEATURES:

• small shunts - asymptomatic

• large PDA - retarded growth and development

• sometimes cardiac failure (dyspnoea - first symptom)

• continous machinery murmur with late systolic accentuation, maximal in the second left intercostal space, accompanied by thrill

• CXR - enlargement of the pulmonary artery

• considerable rise in pulmonary artery pressure

• ECG - usually normal

• Eisenmenger's pathology - central cyanosis, more apparent in the feet and toes than in the upper part of the body; the murmur becomes quieter, may be confined to systole, or may disappear; ECG - right ventricular hypertrophy