Two distinct P waves may complicate interpretation of the immediate postoperative electrocardiogram ( Fig 1). The residual cuffs of native atria contribute one P wave in addition to the transplant-related P wave. A bedside non-invasive test that readily differentiates between the two involves the response elicited by vagal stimulation which affects only the native P wave. A new surgical technique employing bicaval anastomoses eliminates the confusion of two P waves, but is not widely used.
Fig. 1 Twelve-lead electrocardiogram with rhythm strip of a patient after heart transplantation showing two distinct P waves, a native P wave from the right atrial remnant (N) and a donor P wave (D) associated with the QRS complex. (Courtesy of Dr E. Curtiss.)
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