Locating the right phrenic nerve by imaging the right pericardiophrenic artery with computerized tomographic angiography: Implications for balloon-based procedures

doi:10.1016/j.hrthm.2010.03.027

Heart Rhythm

Volume 7, Issue 7, July 2010, Pages 937-941

https://doi.org/10.1016/j.hrthm.2010.03.027 Get rights and content

Background

Phrenic nerve (PN) injury, a known complication of radiofrequency (RF) catheter ablation of atrial fibrillation (AF), has been more commonly reported with balloon-based pulmonary vein isolation.

Objective

We present a novel approach to locating the PN and predicting patients at higher risk of this complication.

Methods

The study included 2 groups of patients. In the first group of 71 patients, computerized tomographic angiography (CTA) with 3-dimensional reconstruction of the left atrium (LA) was obtained prior to an RF ablation procedure. The location of the right pericardiophrenic artery (RPA) was identified on the axial CTA images, and the artery distance to the right superior pulmonary vein (RSPV) ostium was measured in the 3-dimensional image. During ablation, the location of the right PN was identified by pacing maneuvers. The distance to the ostium of the RSPV was measured by venography and compared with the CTA artery measurement. In the second group, CTA imaging from 37 subjects who were enrolled in 3 investigational balloon ablation trials were analyzed using the same PN location technique and compared against the clinical outcomes. In this analysis, the CTA segmentation and PN location was performed in a blinded fashion as to any clinical evidence of PN injury.

Results

The mean measurement difference between PN capture and imaged RPA was 0.8 mm (P = .539). In all cases, the imaged RPA could reliably identify the approximate location of the right PN (R-square 0.984, P < .001). Moreover, this analysis suggests that a PN location within 10 mm of the RSPV poses a higher risk of PN injury using these balloon ablation devices.

Conclusion

Imaging the right pericardiophrenic artery can reliably locate the right phrenic nerve. This technique might identify anatomy more vulnerable to phrenic nerve injury using balloon-based ablation systems.

Section snippets

Methods

Two groups were considered for the study. A baseline validation group and a balloon study group were analyzed. In the first group, 71 patients planning to have catheter ablation procedures for AF underwent CTA studies preoperatively using a 64-slice multidetector computed tomography (CT) scanner (GE Systems, Barrington, Illinois.). The 3-dimensional (3-D) reconstruction of the LA was performed manually by a single operator using a CT workstation (GE Systems). Using the same workstation and

Results

A total of 71 patients were enrolled in the validation study. The mean distance of the RPA to the ostium of the RSPV was 15.2 ± 8.3 mm and with a distance range of 3.0 to 42.6 mm on CTA. In the venogram analysis, the mean distance of the capture site of the right PN to the ostium of the RSPV was 16.0 ± 8.5 mm with a distance range of 3.0 to 42.0 mm. The mean distance difference between the RPA–RSPV compared with the right PN–RSPV was 0.8 mm (P = .539) with a range of 0.0 to 2.6 mm. Figure 2

Discussion

Although no technique has been previously described for preoperative location of the PN in clinical settings, pace mapping of the sites where the nerve can be stimulated from the endocardium has been the most commonly accepted real-time technique.7, 8 Although this is practical and simple to execute, it has limitations. If paralytic agents are used during the anesthesia process, the nerve may not be capable of stimulation at that time.⁹ Moreover, high-energy pacing can demonstrate large regions

Conclusion

Imaging the RPA can reliably locate the right PN. This technique might identify anatomy more vulnerable to PN injury using balloon-based ablation systems.

References (16)

D.A. Cesario et al.
Lesion-forming technologies for catheter ablation of atrial fibrillation
Heart Rhythm J
(2007)
W.B. Meijboom et al.
Diagnostic accuracy of 64-slice computed tomography coronary angiography: a prospective, multicenter, multivendor study
J Am Coll Cardiol
(2008)
T. Neumann et al.
Circumferential pulmonary vein isolation with the cryoballoon technique
J Am Coll Cardiol
(2008)
T.J. Bunch et al.
Mechanisms of phrenic nerve injury during radiofrequency ablation at the pulmonary vein orifice
J Cardiovasc Electrophysiol
(2005)
R. Bai et al.
Phrenic nerve injury after catheter ablation: should we worry about this complication?
J Cardiolovasc Electrophysiol
(2006)
F. Sacher et al.
Phrenic nerve injury after catheter ablation of atrial fibrillation
Indian Pacing Electrophysiol J
(2007)
D. Sanchez-Quintana et al.
How close are the phrenic nerves to cardiac structures? Implications for cardiac interventionalists
J Cardiovasc Electrophysiol
(2005)
M. Arruda et al.
Electrical isolation of the superior vena cava: an adjunctive strategy to pulmonary vein antrum isolation improving the outcome of AF ablation
J Cardiovasc Electrophysiol
(2007)

There are more references available in the full text version of this article.

Cited by (41)

State of the art paper: Cardiac computed tomography of the left atrium in atrial fibrillation
2023, Journal of Cardiovascular Computed Tomography
The clinical spectrum of atrial fibrillation means that a patient-individualized approach is required to ensure optimal treatment. Cardiac computed tomography can accurately delineate atrial structure and function and could contribute to a personalized care pathway for atrial fibrillation patients. The imaging modality offers excellent spatial resolution and has been utilised in pre-, peri- and post-procedural care for patients with atrial fibrillation. Advances in temporal resolution, acquisition times and analysis techniques suggest potential expanding roles for cardiac computed tomography in the future management of patients with atrial fibrillation. The aim of the current review is to discuss the use of cardiac computed tomography in atrial fibrillation in pre-, peri- and post-procedural settings. Potential future applications of cardiac computed tomography including atrial wall thickness assessment and epicardial fat volume quantification are discussed together with emerging analysis techniques including computational modelling and machine learning with attention paid to how these developments may contribute to a personalized approach to atrial fibrillation management.
Novel technique to avoid diaphragmatic paralysis during focal ablation of a non–pulmonary vein trigger mapped to the crista terminalis
2017, HeartRhythm Case Reports
Preventing Phrenic Nerve Injury During Second Generation Cryoballoon Ablation: What Will it Take?
2016, JACC: Clinical Electrophysiology
Prevalence and Pre-Procedural Predictors Associated With Right Phrenic Nerve Injury in Electromyography-Guided, Second-Generation Cryoballoon Ablation: Single Large Balloon and Single 3-Minute Freeze Techniques
2016, JACC: Clinical Electrophysiology
Citation Excerpt :
Matsumoto et al. (15) initially showed the feasibility of using 64-slice MDCT for the detection and anatomic outline of the phrenic nerves and their relation to the cardiac anatomic structures. Subsequently, Horton et al. (16) proved that imaging the RPCB could reliably locate the right phrenic nerve, and that a phrenic nerve location within 10 mm of the RSPV posed a higher risk of PNI when using balloon ablation devices, by analyzing 7 of 37 patients with PNI after any balloon procedure (4 of 18 patients who underwent high-intensity focused ultrasound, 2 of 13 with a laser balloon, and 1 of 6 patients with a first-generation CB). However, the study included only 6 patients who underwent a first-generation CB ablation.
This study aimed to evaluate the incidence and pre-procedural predictors of right phrenic nerve injury (PNI) in electromyography-guided, second-generation cryoballoon (CB) ablation.
Second-generation CBs perform better pulmonary vein isolation (PVI) than first-generation CBs; however, right PNI remains a concern.
One hundred consecutive patients with paroxysmal atrial fibrillation who underwent cryoablation were prospectively enrolled. Contrast-enhanced cardiac multidetector computed tomography (MDCT) was obtained pre-procedurally. PVI was performed with one 28-mm second-generation balloon using a 3-min freeze technique under electromyography guidance.
In all, 377 of 392 (96.2%) PVs were isolated using a CB. In 9 (9.0%) patients, right PNI was observed during the ablation of the right superior PV (RSPV). All events occurred during freezing, except for 1 that occurred during thawing. Right peri-cardiophrenic bundles (RPCBs) were identified at the level of the RSPV on MDCT in 97 patients. In the logistic regression analysis, the distance from the RSPV ostium to the RPCBs (hazard ratio: 0.263; 95% confidence interval [CI]: 0.110 to 0.630; p = 0.003) was the sole predictor of PNI. The optimal cutoff point for the distance for predicting right PNI was 12.4 mm (sensitivity 96.6%, specificity 88.9%) with an area under the curve of 0.968 (95% CI: 0.922 to 1.000). The PNI resolved spontaneously within 1 day and 2 months in 6 and 2 patients, respectively, and at 8 months in the remaining patient, with delayed recognition of an electromyography decrease.
Persistent right PNI is a rare complication during electromyography-guided, second-generation CB ablation. Electromyography should be monitored even during the thawing time. Pre-procedural MDCT might be useful for risk stratification of right PNI.
Multimodality Imaging for Guiding EP Ablation Procedures
2016, JACC: Cardiovascular Imaging
Recent advances in 3-dimensional electroanatomical mapping have been met by continuous improvements in the field of cardiac imaging and image integration during ablation procedures. Echocardiography, computed tomography, cardiac magnetic resonance, and nuclear imaging provide information about cardiac anatomy and ultrastructure of the heart that may be crucial for a successful ablation procedure. Techniques and value of pre-procedural, intraprocedural, and post-procedural imaging and image integration are discussed in this review article. Pre-procedural imaging provides key anatomic information that can be complemented by intraprocedural imaging to minimize procedural complications. Furthermore, the presence and extent of structural heart disease can be assessed pre-procedurally and can be displayed intraprocedurally to limit and focus the mapping and ablation procedure to the area of interest. Pre-procedural imaging combined with imaging obtained during the ablation procedure further enhances procedural safety, reduces exposure to ionizing radiation from fluoroscopy, reduces procedure time, and may improve outcomes.
Effect of cryoballoon inflation at the right superior pulmonary vein orifice on phrenic nerve location
2016, Heart Rhythm
Citation Excerpt :
CMAP is useful for early detection of PNI and has been used clinically.3 However, some patients experience persistent PNI despite use of this method,4,5 and it is not likely to predict PNI “before” cryothermal application. Thus, PN pace-mapping after cryoballoon inflation might be a unique assessment strategy for stratifying risk of PNI.
Cryoballoon catheter ablation was developed to simplify ablation for atrial fibrillation (AF). Initial enthusiasm for its widespread use has been dampened by phrenic nerve (PN) injury (PNI).
The purpose of this study was to assess the effect of cryoballoon inflation at the right superior pulmonary vein (RSPV) orifice on PN location and to elucidate the potential mechanism of PNI.
Twenty patients with paroxysmal atrial fibrillation underwent ablation performed with a second-generation 28-mm cryoballoon catheter. Before ablation, the pacing-determined PN course was delineated along the right atrium. PN location and its relation to the RSPV as well as RSPV surface distortions after balloon inflation were established with a NavX mapping system.
During RSPV ablation, the inflated balloon surface extended anteriorly 6.3 ± 1.8 mm outside the RSPV. This narrowed the distance between the PN capture points in the RSPV vs PN location from 11.4 ± 5.0 mm to 7.5 ± 5.0 mm (P = .0002) and increased the PN capture area from 1.9 ± 1.3 cm² to 3.2 ± 1.8 cm² (P = .0004). Furthermore, the PN capture points shifted toward the orifice within the RSPV and after balloon inflation were located significantly closer to the orifice in the 3 patients with transient PNI than in those without PNI.
Cryoballoon inflation at the RSPV orifice alters PV/left atrial surface geometry, reducing the distance between the energy delivery source and the PN and increasing PN area, possibly explaining the mechanism of PNI. PN pacing within the RSPV after balloon inflation may be useful for preventing PNI.

View all citing articles on Scopus

: Dr. Horton is a Speaker/Consultant for St. Jude Medical, Biosense Webster, Atritech, Inc., Plymouth, Minnesota, Hansen Medical and n-Contact. Dr. Natele is a Speaker for St. Jude Medical, Boston Scientific, Medtronic, and Biosense Webster and an Advisory Board member for Biosense Webster, and has received a research grant from St. Jude Medical.

View full text

GeneralGeneralLocating the right phrenic nerve by imaging the right pericardiophrenic artery with computerized tomographic angiography: Implications for balloon-based procedures

Background

Objective

Methods

Results

Conclusion

Section snippets

Methods

Results

Discussion

Conclusion

Heart Rhythm J

J Am Coll Cardiol

J Am Coll Cardiol

Mechanisms of phrenic nerve injury during radiofrequency ablation at the pulmonary vein orifice

J Cardiovasc Electrophysiol

Phrenic nerve injury after catheter ablation: should we worry about this complication?

J Cardiolovasc Electrophysiol

Phrenic nerve injury after catheter ablation of atrial fibrillation

Indian Pacing Electrophysiol J

How close are the phrenic nerves to cardiac structures? Implications for cardiac interventionalists

J Cardiovasc Electrophysiol

Electrical isolation of the superior vena cava: an adjunctive strategy to pulmonary vein antrum isolation improving the outcome of AF ablation

J Cardiovasc Electrophysiol

General
General
Locating the right phrenic nerve by imaging the right pericardiophrenic artery with computerized tomographic angiography: Implications for balloon-based procedures