Common trunk of the inferior pulmonary veins: an unexpected anatomical variant detected before ablation by multi-slice computed tomography

A 66-year-old man with a history of hypertension and prior percutaneous revascularization for angina pectoris was referred for ablation of paroxysmal atrial fibrillation not responsive to antiarrhythmic drug therapy. The patient never complained of rest or effort dyspnoea; chest X-ray was normal and echocardiography showed only mild septal hypertrophy with normal-sized atria and no sign of pulmonary hypertension. Data set of the pre-procedure computed tomography (CT) scan (Aquilion 64 Toshiba Medical System, Japan) was imported into the electroanatomical system and segmented by using dedicated software (CartoMerge, Biosense-Webster, Inc., USA) to obtain three-dimensional anatomy of the left atrium and pulmonary veins (PVs). As shown in Figure 1A, the superior PVs had normal anatomy and course, whereas a large common trunk of the inferior PVs was present in the postero-medial wall. This common trunk directly received the right inferior vein, while the left inferior vein had a 90° junction with the trunk and showed a clear imprint of the oesophagus and the descending aorta (Figure 1B). During the procedure, angiography clearly identified PV ostia, but selective visualization of the left inferior vein could not be accomplished due to its take-off angle. Electrical PV isolation was successfully performed without complications. Three-dimensional imaging of multi-slice CT-scan in postero-anterior (A) and right cranial view (B). This finding represents an unusual variant of PV anatomy, being the first major and unexpected PV abnormality we encountered in the first 55 cases evaluated by CT-scan before the procedure. If it had not been recognized beforehand, the procedure could have been prolonged and possibly compromised in safety, by fruitless attempts to identify the left inferior PV os at its usual location. The wide range of possible anatomical variants of the PVs seems to justify radiation exposure, time, and resources used for pre-procedure three-dimensional imaging.