Clinical features of patent ductus arteriosus

Children are often asymptomatic and may be only diagnosed on findings of examination. Possible symptoms include:

• fatigue
• failure to thrive
• breathlessness on exertion
• recurrent chest infections

On examination:

• the patient often appears normal, unless the patent ductus is part of the rubella syndrome.
• the pulse is of large amplitude with a sharp upstroke, and the aortic diastolic pressure is low
• the jugular venous pressure is normal
• the dilated and hypertrophied left ventricle results in a prominent apex beat

On auscultation:

• continuous machinery murmur maximal under the left clavicle. As the pulmonary vascular resistance increases the velocity of the shunt decreases and the murmur may become confined to systole. A very high pulmonary vascular resistance will mean that there is no shunt and no murmur.
• flow murmurs - an apical mid-diastolic flow murmur can be heard when the pulmonary blood flow is about twice the systemic. This murmur is produced by excessive return across the mitral valve.
• second sound is dependent on the size of the ductus. The larger the ductus the larger the volume of the left ventricular systolic volume, and hence the longer the delay of the closing of the aortic valve (A2). These features mean that with a large ductus the two heart sounds may become merged or even become paradoxically split, i.e. P2 before A2.