We report a case of superiorly directed sinus p-waves in a young patient
who had extensive right atrial scarring due to prior right atriotomies.
This sinus p-wave axis then changed to inferiorly directed after
catheter ablation of the cavo-tricuspid isthmus (CTI). Normal p-wave
morphology during sinus rhythm has been described as having an axis
between 0 to +75 degrees. However, this is contingent upon an otherwise
healthy atrium without conduction abnormalities. Our case highlights a
young patient who has undergone two mitral valve surgeries, and as a
result, two right atriotomies for cardiopulmonary bypass. During
follow-up after the second surgery, his unusual p-wave axis was noted
and it was unclear whether it was due to an atrial escape rhythm that
had overtaken the sinus node or abnormal conduction of sinus rhythm.
Electroanatomic activation mapping proved that he indeed had a sinus
rhythm with conduction abnormality along the sites of his previous
atriotomies. Additional ablation on the other side of the sinus node
exit resulted in pseudo-normalization of his p-wave axis morphology.
Four week follow up showed persistent inferiorly directed P wave, a
finding in this patient consistent with persistent block across the
caval tricuspid isthmus.