Superior Vena Cava Rhythm Masquerading as Normal Sinus Rhythm.

SVC Rhythm Masquerading as NSR . We report the case of a patient with persistent cardiac rhythm originating from the superior vena cava (3 cm above the vena cava-atrial junction). It was detected by noncontact balloon mapping before induction of tachycardia and confirmed by conventional contact mapping with image studies. Thus, a 12-lead ECG showing normal morphologies of P waves may not indicate that the P waves are of sinus node origin. (J Cardiovasc Electrophysiol, Vol. 15, pp. 950-952, August 2004) [ABSTRACT FROM AUTHOR]