Natural history of isolated partial anomalous pulmonary venous connection with intact inter-atrial septum

Background: Isolated partial anomalous pulmonary venous connection with an intact inter-atrial septum is a relatively uncommon condition, with hemodynamic impact similar to the ones observed in patients with an atrial septal defect. Patients with a single anomalous vein are usually asymptomatic; generally such anomaly does not have significant hemodynamic impact and surgical repair is unnecessary. However, their natural history remains unclear.

Materials and Methods: We reviewed our institutional database to identify patients with either one or two anomalous pulmonary veins that drain less than half the lung. Patients, who have undergone surgical cardiac repair, in whom the anomalous veins drain the whole lung, or Scimitar syndrome was excluded. We reviewed their clinical charts and investigations.

Results: We identified 41 patients with single, and 13 patients with 2 anomalous pulmonary veins. Thirty were male. Mean age at the time of latest clinic visit was 47.6±19.3 years (18 - 84 years). Turner syndrome (6/54, 11.1%), bicuspid aortic valve (6/54, 11.1%) and coarctation of the aorta (5/54, 9.3%) were commonly associated anomalies. Anomalous left upper lobe vein was the most commonly identified anomaly. More than half of the patients were asymptomatic, whereas chest pain, dyspnea, palpitation and audible murmur were present in others. Trans-thoracic echocardiography demonstrated mean right ventricular basal diameter of 4.4±0.8 cm, and estimated right ventricular systolic pressure of 38±13 (16-84) mmHg; eight patients had moderate to severe tricuspid regurgitation. Cardiac magnetic resonance in 43 patients demonstrated mean indexed right ventricular end-diastolic volume, of 124±30 ml/m² (66-188 ml/m²), exceeding 150ml/m² in 8 (14.8%) patients. CMR based Qp:Qs calculation was 1.6±0.3. Five (9.3%) patients had established pulmonary hypertension, of whom 4 had a single anomalous pulmonary vein. Repeat CMR in 12 patients at 4±2 years, demonstrated mean change in absolute right ventricular volume of 4.5 ml, suggestive of time dependent progression of RV dilation.

Conclusion: Patients with unrepaired, isolated partial anomalous pulmonary venous connection, and intact inter-atrial septum do not have a benign course as suggested previously. Chronic volume overload from such a defect can result not only in significant right ventricular dilatation, but can also establish pulmonary hypertension. Patients with such anomaly should be followed-up regularly so that they can be treated in a timely manner.