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Mediastinal Carcinoma Invading the Left Inferior Pulmonary Vein and Presenting as Refractory Atrial Arrhythmia

August 2002 PACE, Vol. 25, No. 8 Case Report A 68-year-old Caucasian man with a longstanding history of smoking and alcohol abuse developed atrial fibrillation with rapid ventricular response shortly after a radical laryngectomy for squamous cell carcinoma of the hypopharynx. Echocardiography revealed an ejection fraction of 0.40 and normal atrial sizes. Over the following few weeks, paroxysmal atrial flutter recurred frequently with rapid ventricular rates despite oral diltiazem and maintenance amiodarone after a standard load. During electrophysiological study, right atrial mapping was achieved with a roving quadripolar ablation catheter, a duodecapolar catheter encompassing the low right atrium, and the coronary sinus and a decapolar catheter placed along the posterior interatrial septum with the distal pole at the superior vena cava to right atrial (SVC-RA) junction. The clinical arrhythmia was easily induced with double atrial extrastimuli with the earliest atrial activity at the distal pole of the decapolar catheter preceding the onset of surface lead atrial activation by 26 ms and with significant fractionation of the recorded electrogram. Postpacing intervals obtained after entrainment from the isthmus excluded isthmus dependency. Entrainment was not possible from the earliest site at the SVC-RA junction. Test burns applied to that site did not alter the arrhythmia. At this point it was decided to map the left atrium in a separate session. Computerized tomography with contrast for anatomic definition of the pulmonary veins was performed in anticipation of left-sided study and ablation. This revealed a mediastinal tumor encasing the descending aorta that had not been detected on preoperative chest X rays. The tumor extended anteriorly to envelope the left inferior pulmonary vein with near occlusion of the latter and apparent invagination of the tumor into the left atrial body (Fig. 1). Subsequently, bronchoscopic biopsy demonstrated squamous cell carcinoma. This was thought to be a second primary tumor rather than a secondary.