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We Know What the Cardiac Surgeon Did During Last Hybrid Arrhythmia Procedure

Kumar, Narendra MD, PhD; Pison, Laurent MD, PhD; Gelsomino, Sandro MD, PhD; Aksoy, Ismail MD; La Meir, Mark MD, PhD; Maessen, Jos MD, PhD

Innovations:Technology and Techniques in Cardiothoracic and Vascular Surgery: January/February 2017 - Volume 12 - Issue 1 - p 67–70
doi: 10.1097/IMI.0000000000000343
Case Reports

Superior vena cava (SVC) is an important source of origin of atrial fibrillation (AF) triggers other than a pulmonary vein. Because of the proximity of SVC-aorta ganglionic plexi to the SVC and the extension of myocardium in the SVC from the right atrium, SVC frequently becomes an important source of ectopic beats initiating AF. The potential complications of SVC isolation may include sinus node injury. Sinus node isolation was observed in a patient who had undergone previous surgical isolation of SVC for AF, while attempting to ablate endocardially, near the superior part of interatrial septum for an atrial tachycardia.

From the Departments of *Cardiology and †Cardiac Surgery, Maastricht University Medical Centre and Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands; and ‡Admiraal de Ruiter Hospital, Goes, The Netherlands.

Accepted for publication June 3, 2015.

Disclosures: Mark La Meir, MD, PhD, and Laurent Pison, MD, PhD, are consultants for AtriCure, Inc, West Chester, OH USA. Narendra Kumar, MD, PhD, Sandro Gelsomino, MD, PhD, Ismail Aksoy, MD, and Jos Maessen, MD, PhD, declare no conflicts of interest.

Address correspondence and reprint requests to Narendra Kumar, MD, PhD, Department of CTC, Maastricht University Medical Centre and Cardiovascular Research Institute Maastricht, PO Box 6202AZ, Maastricht, The Netherlands. E-mail:

Surgical ablation is a promising technique in the treatment for atrial fibrillation (AF), which potentially cures AF radically and emancipates patients from bothersome antiarrhythmic drug treatments. The isolation of superior vena cava (SVC) is effective especially in patients with paroxysmal AF from SVC origin. Temporary sinus node (SN) isolation was observed in a patient during endocardial ablation of superior part of interatrial septum, with previous surgical ablation of SVC.

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A 62-year-old euglycemic and normotensive woman has a history of bronchial asthma for 14 years, persistent AF for 4 years, and smoking for 3 years. Initially, she underwent pulmonary vein (PV) isolation using a circular multielectrode ablation catheter (Pulmonary Vein ablation catheter; Medtronic, Inc, Minneapolis, MN USA) in December 2011. Later, she underwent reisolation of PVs with radiofrequency (RF) catheters in August 2012 because of symptomatic AF episodes. She was managed with antiarrythmic drugs until June 2013 when she underwent a redo PV isolation using a cryoballoon and cavotricuspid isthmus ablation for symptomatic typical atrial flutter. In August 2013, because of her persistent complaints, hybrid procedure was advised. The procedure was carried out as described elsewhere.1 To summarize, after femoral venous access, an electrophysiologist checked for isolation of the PVs. Accordingly, thoracoscopic PV isolation of only left PVs, a box lesion, SVC isolation, and ligament of Marshall ablation was conducted using bipolar RF clamps and pen devices (AtriCure, Inc, West Chester, OH USA). Finally, left atrial (LA) appendage was ligated with an epicardial clip (AtriClip, AtriCure, Inc). The box lesion consists of a superior line connecting the left and right superior PVs and an inferior line connecting both the left and right inferior PVs. In May 2014, she was readmitted because of symptomatic and recurrent episodes of atrial tachycardia (AT). The patient continued to have AT while she was shifted to procedure room.

The earliest activation map localized the recurrent AT (cycle length = 210 milliseconds) to the right side of midsuperior part of the interatrial septum using an ENSITE system (St. Jude Medical, Inc, St. Paul, MN USA). Ablation there with the irrigated tip RF catheter (48°C, 30 W) stopped the AT (Fig. 1). After several seconds, AT recurred with irregular cycle length but similar activation pattern noted on coronary sinus (CS) catheter. The new electroanatomical map showed no earlier activation in right atrium but in LA at inferior and anterior aspect of interatrial septum (Fig. 1) at 1.5 cm away from his site marked during mapping. Radiofrequency application at this site terminated the AT (Fig. 2A), and a slow junctional escape rhythm with retrograde atrial activity on the CS intracardiac recordings started with dissociated SN activity (also not observed on CS catheter recordings). Starting 1 μg/min of isoproteronolol infusion showed spontaneous recovery of 1:1 conduction within 2 minutes (Fig. 2B). No new AT was seen while testing with burst pacing.





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Superior vena cava is the most common non-PV foci that initiates AF among 26% to 28 % of AF patients. Other common foci include crista terminalis, LA posterior wall CS ostium, ligament of Marshall, and interatrial septum.2 Distinct histological findings of heterogeneous fiber arrangements and degenerative changes of myocardium with penetrating fibrous tissue are commonly identified in SVC myocardium that may form substrates for an arrhythmogenicity.3 The role of SVC triggers to AF maintenance may be doubted but definitely cannot be ignored.3–5 Several authors and 2012 Heart Rhythm Society/European Heart Rhythm Association/European Cardiac Arrhythmia Society Expert Consensus Statement on Catheter and Surgical Ablation of AF mention an encircling lesion of the SVC to isolate it.6,7 Remnants of cardiac conduction system (pacemaker cell) are located in PVs and SVC, crista terminalis, and/or CS that become suitable ablation targets for atrial arrhythmias. Because these remnants can become arrhythmogenic foci triggering AF, treating them assumes importance in ablation therapy of AF.8–10 Such observations have motivated multiple investigators to map and ablate individual foci of ectopic activity to attempt to cure AF.11–15 Although SVC has thin tissue, its thickness may not guarantee a transmural lesion. However, bipolar clamps have been associated with better success rate that may be attributed to better transmurality of lesions.16

The SN is 13.5 ± 2.5 mm long that is not insulated by a sheath of fibrous tissues and located at the superior end of the crista terminalis. Its morphology is crescent like rather than fusiform or horseshoe. SN injury during SVC isolation is defined as sinus pause of greater than 3 seconds, significant sinus bradycardia, or persistent slow junctional rhythm after ruling out the vagus reflex with atropine and/or dopamine administration. Previously, SN dysfunction has been reported after SVC isolation, SVC stenting,17 and after extensive ablation of the right atrium including isthmus line, anterior line, and intercaval line.18

In this case, the endocardial RF application at right atrium temporarily resulted in SN isolation as seen with junctional escape rhythm with retrograde atrial activity on CS ECG recordings, lest we forget same patient who underwent previous attempt for SVC surgical isolation. Retrospectively, the previous surgical isolation with placement of distal end of ablation clamps extending up to interatrial septum, and subsequent endocardial ablation completed the isolation of the SVC, and the SN too, was concluded as the etiology. However, isoproteronolol infusion helped in resumption of SN activity. The clinical follow-up of patient is nonremarkable with 7-month follow-up.

Superior vena cava isolation during AT may have higher incidence of SN injury.3 Abnormal heart rhythm seen after injuring the SN for example, junctional rhythm, sinus arrest, or significant sinus bradycardia, and sign of close proximity to the SN such as sinus automaticity (heart rate acceleration) may not be observed during AF or atrial flutter.

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Prevention Strategies

To prevent any damage to SVC, clear demarcation of junction of SVC to right atrium is immensely important. The highest priority should be given to use of imaging modalities as multiple projections of SVC angiography, Intracardiac echocardiography, high-density electroanatomical mapping (especially to demonstrate earliest activation to demarcate SN), and direct visualization of the distal end of clamps used by a surgeon. “Double potentials consisting of far-field atrial potentials and SVC potentials” recorded at the junction of the SVC and right atrium can be of immense help endocardially. With aim to avoid SN injury, the anteroseptal wall ablation of the junction of right atrium and the SVC should be more preferred at a lower level than anterolateral free wall.3

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Superior vena cava isolation should be conducted after careful visualization of application site to avoid unnecessary ablations and complications as SN injury.

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Surgical ablation; Atrial fibrillation; Minimally invasive; Complication; Superior vena cava; Sinus node

©2017 by the International Society for Minimally Invasive Cardiothoracic Surgery