抄録
Case: The patient was a 63-year-old man. In October 2008, he underwent CRTD implantation for chronic heart failure and ventricular tachycardia associated with old myocardial infarction. During a visit to the pacemaker clinic in December 2010, pacing waves and spontaneous waves appeared in an alternating fashion on a 12-lead ECG. Intracardiac ECG revealed T wave over-sensing after ventricular pacing, followed by atrial waves (sensing during the refractory period), resulting in inappropriate ventricular pacing. This phenomenon could not be avoided by resetting the threshold for ventricular sensing. When the AV delay was shortened to 150 ms, the T wave amplitude decreased on intracardiac ECG, and the T wave over-sensing disappeared. Discussion: In this case, shortening of AV delay modified conduction, which in turn decreased the T wave amplitude and prolonged the ventricular refractory period, probably resulting in disappearance of the T wave over-sensing. Considering sensing threshold characteristics, the ventricular sensing threshold probably explains the inappropriate to avoid T wave over-sensing prior to the intervention in this case.
