A 70-year-old man with a history of atrial fibrillation and mitral valve disease underwent a redo mitral valve replacement and repeat surgical maze procedure a few years ago, at which time his left atrial appendage had already been excised. He developed refractory symptomatic persistent atrial tachycardia, and underwent a catheter ablation procedure. High-density (HD) voltage and activation maps of the left atrium were created using a multielectrode mapping catheter with closely spaced, small-sized electrodes. Electrograms accounting for most of the tachycardia cycle length could be recorded at the left atrial roof, and the activation map is shown in Figure 1 and accompanying video (available soon at www.eplabdigest.com). There was a long, very low amplitude, fractionated electrogram at the center of this circuit, and the post-pacing interval was equal to the tachycardia cycle length. The differential diagnosis was perimitral flutter versus localized reentry at the roof using a small figure of eight circuit. The apparent collision of wavefronts lateral to the site of very slow conduction, and a post-pacing interval of 50 msec in the lateral coronary sinus, argued against perimitral flutter. The tachycardia terminated within 7 seconds during ablation at this site, and the tachycardia was noninducible after a cluster of five 30 Watt lesions were delivered nearby using an irrigated electrode.
The rest of Dr. Bradley Knight's April 2019 editorial, as well as an accompanying clinical video, will be available soon!