PDA (Patent ductus arteriosus)

Images by Genevieve Carbonatto   PSAX view Jet from PDA, flow from aorta to pulmonary artery

Parasternal long axis of the left ventricle, (LV).  The LV appears to be a little dilated.  Image is slightly tilted towards the right hip, as part of the tricuspid valve is seen, this can make the Right Ventricle (RV) appear slightly dilated.  Look at RV in multiple views to assess size qualitatively.

Parasternal short axis at the level of mitral valve and papillary muscle.  Heart motion with repiration. RV does not appear to be dilated in this view, however LV looks slightly dilated.

Parasternal short axis at the level of the pulmonary valve, (PV).  The PV is just seen to the right of the aortic valve.

Parasternal short axis at the level of the pulmonary valve, (PV), main pulmonary artery, (MPA) and pulmonary bifurcation.  Note the descending thoracic aorta, (D.Th.A.) in cross-section posterior to the pulmonary bifurcation.  Note also the position of the pulmonary valve leaflets to assist with the next image.

Parasternal short axis with colour flow imaging across the PV and main pulmonary artery.  Forward flow in systole is in blue and two red jets are seen during diastole on this image.  The more anterior red jet, (closer to the probe) originates from the PV, so is pulmonary regurgitation, (PR).  The second red jet originates from close to the pulmonary bifurcation and is suggestive of a Patent Ductus Arteriosus, (PDA).  The flow across a PDA is continuous throughout the cardiac cycle,  as the pressure in the Aorta is always greater than the pressure in the MPA.   In this case the flow is moving out of he scan plane during systole and the jet from the PDA is not seen.  The left heart dilates with a PDA, as the left heart is volume overloaded.  A “machinery” murmur can be heard with a stethoscope.

 

A PDA (patent ductus arteriosus)  is a persistent communication between the descending aorta and the pulmonary artery due to failure of closure of the ductus arteriosus.

The physiological impact and clinical significance of the PDA depend largely on its size and the underlying cardiovascular status of the patient. The PDA may be “silent” (not evident clinically but diagnosed incidentally by echocardiography done for a different reason), small, moderate, or large.

Left-to-right shunting through the ductus arteriosus results in increased pulmonary circulation and left heart volume overload. Increased pulmonary flow from the ductal shunting leads to increased pulmonary fluid volume, and in patients with moderate or large shunts, this causes decreased lung compliance, which may result in increased work of breathing.

Adults with undiagnosed  PDA may present with signs and symptoms of heart failure, atrial arrhythmia (due to progressive left atrial enlargement) or even differential cyanosis limited to the lower extremities, indicating shunting of deoxygenated blood from the pulmonary to systemic circulation.

The clinical history of patients however varies from those who are completely asymptomatic to those with severe congestive heart failure or Eisenmenger’s syndrome. Most patients compensate well even with a moderate left-to-right shunt and remain asymptomatic during childhood however many years of chronic volume overload may lead to symptoms of congestive heart failure in adulthood.

 

Reference

1. Circulation: CONGENITAL HEART DISEASE FOR THE ADULT CARDIOLOGIST
   Patent Ductus Arteriosus,   October 24, 2006
   Douglas J. Schneider and John W. Moore