1357370 - Breathlessness following surgical redirection of variant Scimitar Vein (SV) partial anomalous pulmonary venous drainage (PAPVD)

A 26 year old Caucasian female with variant SV PAPVD to the IVC underwent surgical correction with an initial baffle operation. This successfully alleviated symptoms of dyspnoea. Over the next 6 months, she presented to her local hospital with recurrent cough and sweats. Infection screen including blood cultures were negative. The local CT thorax showed unilateral diffuse right lung nodularity with bulky right hilar and mediastinal lymph nodes. Lung bronchoscopy was unremarkable. The patient was referred to the Adult Congenital Heart Disease team for further evaluation and diagnostic imaging.

Diagnostic Techniques and Their Most Important Findings: The native anatomy is demonstrated (Fig 1). There is a large left to right shunt (Qp:Qs 2.0:1) with volume loading of the right heart (RVEDV:LVEDV 2.1:1, RVEDV 150ml/m²) and no preferential flow between the lungs. No aortic collateral feeder to the right lung, right lung sequestration or hypoplasia was demonstrated on time-resolved contrast enhanced MR angiography (ceMRA).

Surgical redirection involved baffling the anomalous SV though the IVC, across the RA and into the LA via a surgically created atrial septal defect. A diagnostic CMR was performed following the first surgery. Despite a resolution of RV volume loading, time-resolved ceMRA revealed obstruction of the baffle at the IVC level with minimal flow and markedly reduced RPA flow (RPA 9%:LPA 91%) (Fig 2).

The baffle was surgically revised, which included RA wall plasty and a fenestration between the baffle and RA was left. Serial time-resolved ceMRA showed ongoing reduced perfusion to the right lung (Fig 2) with significant flow differential between the lungs (RPA18%:LPA 82%).
A 3D model showed the anatomical relationship of the SV to the IVC and diaphragm (Fig 3). The obstruction within the proximal reconstructed baffle was stented percutaneously (Fig 2). A month later, the patient developed dyspnoea. A chest radiograph revealed a collapsed stent (Fig 3) and the patient successfully underwent re-stent angioplasty with 2 covered stents.

Learning Points from this Case: Patients with SV PAPVD undergoing surgery are at high risk of postoperative pulmonary vein (PV) stenosis and reintervention [1-3] which relates to the angulation of the SV to the IVC [4, 5]. Unilateral pulmonary venous hypertensive congestion is a red flag for PV obstruction. CMR, including time-resolved ceMRA, is essential for identifying early and late postoperative complications.
Here, 3D modelling not only delineated the degree of SV angulation, but effectively showed the impact of tension created by the musculofibrous convex diaphragm on the SV coursing horizontally towards the IVC. This contributed to recurrent PV obstruction.
Whilst surgical redirection can eliminate the left to right shunt across the spectrum of SV PAPVD, the risk of reintervention and long-term reduction in lung perfusion potentially outweighs this benefit. Selective pulmonary arterial banding may offer a novel approach to reduce the risk of pulmonary venous congestion in this challenging setting.