Spontaneous Localized Persistent Atrial Fibrillation with an Exit Block Mimicking Atrial Tachycardia at the Left Posterior Wall

We describe a 37-year-old man with spontaneous localized atrial fibrillation (AF) with an exit block at the posterior wall of the left atrium (LA). The 12-lead ECG exhibited an atrial tachycardia-like pattern, with distinctive P waves and an isoelectric baseline between the P waves. The cycle length of the P waves ranged from 320 to 500 msec. While the fractionated and rapid deflections were recorded from the posterior wall of the LA, the rest of the atria and the coronary sinus exhibited discrete atrial potentials with irregular intervals. Radiofrequency energy applications to the surrounding tissue created complete isolation of the localized AF area, and the AF was terminated. Fibrillatory activation in the posterior wall of the LA can act as a driver as well as an initiator of atrial fibrillation

A Case with no Hemodynamic Benefit from Right Ventricular Anodal Capture during Biventricular Pacing

This case report describes a patient with a biventricular pacing system in whom right ventricular anodal capture had no hemodynamic benefit. While controlling the ventricular output, three morphologies of the paced QRS complex were obtained: right ventricular stimulation, biventricular stimulation, and biventricular pacing with additional stimulation from the anodal electrode in the right ventricle. While the QRS duration was 5 ms longer, the left ventricular systolic pressure and dP/dtmax during biventricular pacing without anodal capture of the right ventricle were greater than that during biventricular pacing with anodal capture. To avoid useless high output settings, the hemodynamic and clinical data should be compared with and without right ventricular anodal capture in each individual patient