Pulmonary artery size and function after Fontan operation at a young age

Area of Science:

• Cardiovascular Medicine
• Pediatric Cardiology
• Medical Imaging

Background:

• The Fontan operation is a palliative procedure for single-ventricle congenital heart defects.
• Long-term outcomes and potential vascular complications after the Fontan operation require further investigation.

Purpose of the Study:

• To evaluate pulmonary artery (PA) size, flow dynamics, and wall shear stress (WSS) in young patients post-Fontan operation.
• To compare these parameters with healthy controls and assess their response to dobutamine stress.

Main Methods:

• Phase contrast velocity-encoded cardiovascular magnetic resonance imaging (CMR) was used to assess branch PA flow.
• 14 post-Fontan patients were studied before and after low-dose dobutamine stress.
• 17 healthy controls were assessed at rest for comparison.

Main Results:

• Post-Fontan patients exhibited significantly lower resting flow variables (stroke index, total flow, average, and peak flow rate) compared to controls.
• While flow variables increased with dobutamine stress, stroke index remained unchanged.
• Branch PA size was comparable to controls, but distensibility and WSS were significantly reduced in post-Fontan patients, with WSS not reaching control levels even with stress.

Conclusions:

• Pulmonary artery size is maintained long-term after early Fontan operation.
• Reduced flow, distensibility, and WSS in post-Fontan patients suggest pulmonary artery endothelial and/or vascular dysfunction.
• The blunted response to stress testing further supports the presence of vascular impairment.