Treatment of Partial Anomalous Pulmonary Venous Return (PAPVR)
Surgical repair is recommended for PAPVR when patients have impaired functional capacity with RV enlargement, a hemodynamically significant left-to-right shunt (Qp:Qs ≥1.5:1), PA systolic pressure <50% of systemic pressure, and pulmonary vascular resistance <1/3 systemic resistance. 1
Diagnostic Evaluation
Before determining treatment, complete anatomic and hemodynamic assessment is essential:
- CMR or CTA is mandatory to precisely map all pulmonary venous connections and define the complete surgical anatomy 1, 2
- Cardiac catheterization can be useful to directly measure pressures, quantify shunt magnitude (Qp:Qs ratio), measure pulmonary vascular resistance, and assess responsiveness to pulmonary vasodilator therapy 1, 2
- Echocardiography should assess for RV volume overload and associated defects, though cross-sectional imaging is superior for defining extracardiac vascular anatomy 1
Surgical Indications (Class I Recommendations)
Proceed with surgical repair when ALL of the following criteria are met:
- Impaired functional capacity AND RV enlargement present 1
- Qp:Qs ≥1.5:1 (hemodynamically significant shunt) 1
- PA systolic pressure <50% of systemic pressure 1
- Pulmonary vascular resistance <1/3 systemic resistance 1
Mandatory concurrent repair: PAPVR repair is required at the time of closure of any associated sinus venosus defect or ASD 1, 2
Surgical Indications for Scimitar Syndrome
For scimitar vein specifically, repair is recommended when:
- Functional capacity is impaired 1
- RV volume overload is present 1
- Qp:Qs ≥1.5:1 1
- PA systolic pressure <50% systemic 1
- Pulmonary vascular resistance <1/3 systemic 1
Surgical Considerations for Asymptomatic Patients (Class IIa)
Surgery can be useful in asymptomatic adults when:
- RV volume overload is documented 1
- Qp:Qs ≥1.5:1 1
- PA pressures <50% systemic 1
- Pulmonary vascular resistance <1/3 systemic 1
This represents a reasonable approach even without symptoms, given the progressive nature of RV volume overload 3, 4.
Surgical Techniques
Left-sided PAPVR:
- Can often be repaired via left thoracotomy without cardiopulmonary bypass by directly anastomosing the anomalous vein to the left atrium 3, 5
- This minimally invasive approach is associated with excellent outcomes and low morbidity 3, 5
Right-sided PAPVR:
- Typically requires cardiopulmonary bypass with placement of a Dacron or pericardial patch to redirect venous drainage into the left atrium 5
- For isolated PAPVR with intact atrial septum, caval division with pericardial patch baffling through a surgically created ASD and SVC reconstruction may be performed 4
Absolute Contraindications to Surgical Repair
Do NOT perform PAPVR repair when:
- PA systolic pressure >2/3 systemic pressure 1, 2
- Pulmonary vascular resistance >2/3 systemic resistance 1, 2
- Net right-to-left shunt is present (Eisenmenger physiology) 1, 2
Morbidity and mortality are prohibitively high when repair is attempted in these circumstances 1.
Medical Management
Medical therapy alone may be considered when:
- Surgical contraindications exist (elevated pulmonary pressures/resistance) 6
- Patient declines surgery 6
- Shunt is not hemodynamically significant (Qp:Qs <1.5:1)
In select cases with pulmonary hypertension, pulmonary vasodilators (riociguat, ambrisentan) have been used, though this is not standard practice and lacks robust evidence 6.
Critical Pitfalls to Avoid
- Incomplete preoperative anatomic definition: Failing to identify all anomalous pulmonary venous connections can lead to incomplete repair and residual shunting; cross-sectional imaging with CMR or CT is essential before surgery 1, 2
- Operating on patients with established Eisenmenger syndrome: This carries prohibitively high mortality 1
- Delaying repair in symptomatic patients with favorable hemodynamics: Progressive RV dysfunction and pulmonary vascular disease may develop 3
- Missing associated cardiac defects: Always assess for sinus venosus defects and ASDs, which must be repaired concurrently 1
Expected Outcomes
Surgical repair can be accomplished with minimal morbidity and low mortality when appropriate patient selection criteria are met 3, 5, 4. Postoperative improvements include: