Author + information
- Received September 13, 2017
- Revision received October 5, 2017
- Accepted October 12, 2017
- Published online November 15, 2017.
- Gabor Sandorfi, MD,
- Wim Bories, MSBME, MSE, CEPS,
- Hein Heidbuchel, MD, PhD and
- Andrea Sarkozy, MD, PhD∗ ()
- ↵∗Address for correspondence:
Dr. Andrea Sarkozy, Department of Cardiology, University Hospital of Antwerp, Wilrijkstraat 10, 2650 Edegem, Belgium.
A 73-year-old man with atrial fibrillation was referred for pulmonary vein (PV) isolation. Wide antral circumferential ablation was performed around the ipsilateral PVs. Following completion of the circles, adenosine test and pacing maneuvers were performed using a duodecapolar Lasso catheter (Biosense Webster, Diamond Bar, California) (Figure 1). Electrocardiography (ECG) 1 (Figure 1) shows on the left side the tracing atrioventricular dissociation after intravenous adenosine injection, proving the absence of dormant conduction and entrance block in sinus rhythm. The right side of ECG 1 (Figure 1) during pacing is on the Lasso catheter in the right superior PV (RSPV) with consistent signals visible on the Lasso (Figure 1, small arrows) and on the coronary sinus (Figure 1, big dotted arrows) catheters, proving local PV capture and exit to the left atrium. One beat shows local PV capture but does not result in atrial activation (Figure 1, big arrow). ECG 2 (Figure 1) illustrates continuous Lasso pacing in the same position during local PV capture and intermittent conduction to the atrium (Figure 1, small arrows). There is independent PV firing activity (Figure 1, big arrow), suggesting exit blockage on this beat. An atrial fusion beat (Figure 1, asterisk) activates the atrium from the sinus node and from the RSPV pacing at the same time. The differential diagnosis of intermittent atrial capture with RSPV pacing is between intermittent far-field superior vena cava (SVC) capture and intermittent exit conduction from the RSPV to the atrium. ECG 3 (Figure 1) depicts differential pacing with low and high output resulting in PV potentials (Figure 1, small arrows) without (Figure 1A) and with (Figure 1B) atrial capture (Figure 1, dotted arrows), proving intermittent far-field capture of the SVC, subsequently activating the atria. Anatomically, the SVC and RSPV are very close to each other (1), and SVC potentials may appear on the closest Lasso catheter poles, positioned in the RSPV. Differentiating far-field SVC potentials from RSPV by using timing to the surface P wave (30 ms or more ahead suggests SVC) was described in detail previously (2). In our case, we did not observe far-field SVC potentials on the Lasso catheter. However, pacing on the anterior Lasso poles in the RSPV location did result in intermittent far-field SVC capture. Our case illustrates a pitfall of RSPV pacing for evaluating exit block. Adapting the pacing output or pacing a different (posterior RSPV or right inferior pulmonary vein [RIPV]) site (not shown here) may resolve the diagnostic enigma.
Dr. Heidbuchel has received research support from Bracco Imaging Europe, Pfizer, and Bayer through the University of Antwerp; and has been a compensated lecturer and board member for Pfizer, Bristol Myers-Squibb, Daiichi-Sankyo, Boehringer-Ingelheim, Abbott, and Bayer. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Received September 13, 2017.
- Revision received October 5, 2017.
- Accepted October 12, 2017.
- 2017 American College of Cardiology Foundation