The correct answer is number 2: this is flutter of the native atrium, disconnected from the transplanted atrium after cardioversion in a female patient who had undergone a Shumway (biatrial) transplant. The graft also shows sinus dysfunction, with secondary nodal escape (Figure 1). These 2 findings, on their own, are common in transplant recipients,1 particularly following a biatrial technique.2
Diagnosis was confirmed with a temporary epicardial pacemaker (Figure 2). On atrial pacing at 90 bpm, graft atrial capture was achieved, thereby demonstrating that atrioventricular conduction is normal, and so answer 3 is incorrect. Capture also demonstrated that the flutter was derived from the native atrium because otherwise capture of the transplanted atrium could not be achieved at 90 bpm as the flutter has a higher frequency (answer 1 incorrect). In fact, the flutter continues to be dissociated from atrial pacing, as observed when pacing stopped (answer 4 incorrect).
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