Paroxysmal atrial flutter caused by cardiac lymphoma.

Atrial flutter is a relatively frequent macro-reentrant tachycardia that can be caused by a variety of structural and functional atrial changes. Cardiac lymphoma is rare and usually carries a poor prognosis. It preferentially involves the right atrium. This report describes a patient with cardiac follicular B-cell lymphoma who developed paroxysmal atrial flutter. The large tumor mass created a macroscopic substrate for an area of slow conduction which is essential for atrial flutter. It also caused sinus arrest and intermittent obstruction of the tricuspid valve inlet.