A Giant Major Aortopulmonary Collateral Aneurysm in a Patient with Ventricular Septal Defect and Pulmonary Atresia (QF_FR_101)

A girl, 18 years old, was admitted to our hospital. Her past diagnosis was unoperated pulmonary atresia with ventricular septal defect and segmental pulmonary hypertension in major aortopulmonary collateral arteries (MAPCAs). Her current New York Heart Association (NYHA) class was 2, and she had no other symptoms. She had taken bosentan as an anti-pulmonary hypertension medication. When the patient underwent catheter angiography due to regular follow-up of anti-pulmonary hypertension treatment, a giant aneurysm was seen on catheter angiography (Figure 1). Then, the patient was evaluated by cardiac magnetic resonance (CMR) for further examination and pulmonary hypertension risk classification. On CMR, steady-state free precession (SSFP) axial cine imaging showed a large aneurysm with a vortex pattern turbulent flow (Figure 2). Therefore, after the gadolinium injection, contrast-enhanced magnetic resonance angiography (CE-MRA) was performed to better identify vascular structures. CE-MRA revealed this giant saccular aneurysm originated from one of the major aortopulmonary collateral arteries from the right side of the proximal descending thoracic aorta. Before the aneurysm, two branches originating from the proximal part of the MAPCA were supplying the right upper and middle lung. A branch in the inferior of the aneurysm was feeding the lower right lung. On the CE-MRA scan, the aneurysm measured around 60 mm in diameter. This aneurysmatic MAPCA was first connected to the right pulmonary artery. Because there was pulmonary branch confluency, the left lung was also feeding with aneurismatic MAPCA. In addition, there were two small collateral vessels arising from the distal descending aorta, which were feeding the left lung (Figure 3). The patient was discussed at the paediatric cardiology and cardiovascular surgery meeting. Surgery was not considered because of its high risk, so the decision was made for clinical follow-up. We informed the patient about potential emergencies and talked about what they could do in those situations.

Diagnostic Techniques and Their Most Important Findings:

The CMR study was performed using the 1.5-Tesla system (GE Healthcare, Chicago, Illinois) 

After short axis and axial SSFP cine images, two-dimensional phase-contrast flow measurements with gradient echo sequence were obtained from the ascending aorta, main pulmonary artery, and right and left pulmonary arteries. Flow measurements were performed perpendicular to each targeted vessel, and encoding velocity was adjusted to avoid aliasing. A VENC of 80-100 cm/s was chosen for pulmonary arteries due to pulmonary hypertension. After the gadolinium administration (0.01 mmol/ kg), contrast-enhanced MR angiography was performed.

Learning Points from this Case:

MAPCA aneurysm rarely occurs due to high pressure in pulmonary circulation, but its consequences, such as tracheal compression and massive haemoptysis due to rupture, may be vital. An individualised approach is recommended in treatment, taking into account each patient's specific anatomy and physiology. In case of massive haemoptysis due to MAPCA aneurysm rupture, the transcatheter approach can be life-saving in some patients. With this case, we wanted to emphasise that even if a case has no symptoms, MAPCA aneurysms should always be remembered in patients with unoperated pulmonary atresia with VSD. Therefore, detailed CMR evaluation accompanied by angiographic images may be considered.