International Journal of Cardiology 169 (2013) 366–370
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Idiopathic ventricular outflow tract arrhythmias from the great cardiac vein: Challenges and risks of catheter ablation D. Steven a,⁎,1, C. Pott b,1, A. Bittner c, A. Sultan a, K. Wasmer b, B.A. Hoffmann a, J. Köbe b, I. Drewitz a, P. Milberg b, J. Lueker a, G. Mönnig b, H. Servatius a, S. Willems a, L. Eckardt b a b c
The University Heart Center Hamburg, Division of Cardiac Electrophysiology, Germany The University Hospital Münster, Division of Experimental and Clinical Electrophysiology, Department of Cardiology and Angiology, Germany The Pontificia Universidad Católica de Chile, Chile
a r t i c l e
i n f o
Article history: Received 3 June 2013 Received in revised form 21 August 2013 Accepted 27 September 2013 Available online 7 October 2013 Keywords: Catheter ablation Ventricular tachycardia Premature ventricular beats Coronary venous system Coronary artery system
a b s t r a c t Introduction: Catheter ablation for idiopathic ventricular arrhythmia is well established but epicardial origin, proximity to coronary arteries, and limited accessibility may complicate ablation from the venous system in particular from the great cardiac vein (GCV). Methods: Between April 2009 and October 2010 14 patients (56 ± 15 years; 9 male) out of a total group of 117 patients with idiopathic outflow tract tachycardias were included undergoing ablation for idiopathic VT or premature ventricular contractions (PVC) originating from GCV. All patients in whom the PVC arose from the GCV were subject to the study. In these patients angiography of the left coronary system was performed with the ablation catheter at the site of earliest activation. Results: Successful ablation was performed in 6/14 (43%) and long-term success was achieved in 5/14 (36%) patients. In 4/14 patients (28.6%) ablation was not performed. In another 4 patients (26.7%), ablation did not abolish the PVC/VT. In the majority, the anatomical proximity to the left coronary system prohibited effective RF application. In 3 patients RF application resulted in a coronary spasm with complete regression as revealed in repeat coronary angiography. Conclusion: A relevant proportion idiopathic VT/PVC can safely be ablated from the GCV without significant permanent coronary artery stenosis after RF application. Our data furthermore demonstrate that damage to the coronary artery system is likely to be transient. © 2013 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Catheter ablation of sustained ventricular tachycardia (VT) and premature ventricular capture beats (PVC) is an established therapy option especially in patients without structural heart disease [8,15]. High longterm success rates are achievable and the majority of patients with PVC arising from the right or left ventricular outflow tract can successfully be treated using radiofrequency (RF) ablation from the endocardium [6,12]. However, in some patients focal ectopy may arise from the pericardial space, especially the left ventricular summit that in most cases may be reached from the venous cardiac system, namely the great cardiac vein (GCV). It has been shown that epicardial ablation using a subxiphoidal access is also feasible to treat these arrhythmias using radiofrequency (RF) ablation [1,5,11,14]. ⁎ Corresponding author at: Universitäres Herzzentrum Hamburg, Martinistr. 52, 20251 Hamburg, Germany. Tel.: +49 40 7410 54120; fax: +49 40 7410 54125. 1 Both authors contributed equally to this work. 0167-5273/$ – see front matter © 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijcard.2013.09.008
The least invasive access to target epicardial outflow foci is obtained via the venous cardiac system. In this setting, it is important to be aware of potential limitations that may be encountered when aiming for outflow tract VT/PVC ablation from the GCV. First, the epicardial access may not be easily achievable due to anatomic consideration, e.g. a Thebesian valve or small diameter vessels. Second, as in most cases radiofrequency is used to aim for these foci, energy delivery may be limited due to high impendances and limited irrigation flow. Third and potentially most importantly, the close proximity of the GCV to the coronary artery system and other anatomical structures such as the phrenic nerve may pose limitations for RF application in the GCV. Despite the fact that coronary artery injury has been described to be a rare entity (0.09%) during catheter ablation of atrial or ventricular tachycardia this potentially devastating complication has to be kept in mind, especially when ablating in the coronary sinus [7]. The aim of the present study was to evaluate the possibilities and challenges using RF energy to target these foci from the epicardium and to clarify the associated risks when ablating in close proximity to the coronary artery system.
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Table 1 Baseline characteristics of patients included to the study (m = male; f = female; DCM = dilative cardiomyopathy; ICM = ischemic cardiomyopathy; PVC = premature ventricular capture beat, nsVT = non-sustained ventricular tachycardia).
#1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14
Gender
Age
Structural heart disease
VT/PVC
Ablation attempted
Effective energy application
Primary success
Long-term success
M F M F M M F F M M M F M F
75 49 28 62 73 48 39 68 73 56 57 30 56 54
ICM No No No No No No No No No DCM No No No
PVC PVC PVC PVC PVC PVC PVC PVC PVC PVC nsVT PVC nsVT PVC
No Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes
No Yes Yes No No No Yes Yes No Yes Yes Yes No No
No Yes Yes No No No Yes Yes No Yes No Yes No No
No Yes Yes No No No Yes Yes No Yes No No No No
2. Methods Patients undergoing catheter ablation for symptomatic idiopathic VT or PVC were included in two high volume centers (University Hospital Hamburg-Eppendorf and University Hospital Münster) if the following criteria were met: 1. Typical 12 lead ECG outflow tract morphology (inferior axis, positive R waves in leads II and III) 2. Ectopy originating from the outflow tract area with the earliest local activation time in the GCV (after GCV leaves the interventricular groove and enters the mitral valvular level) after mapping of the RVOT and/or left ventricular cavity and outflow tract area 3. Absence of anatomical substrate for VT 4. Attempt to abolish VT/PVC using RF energy from the GCV 5. Coronary angiography before and after ablation in the GCV
Two patients had additional structural heart disease (dilative cardiomyopathy, n = 1; ischemic cardiomyopathy, n = 1). All patients gave written informed consent and underwent conscious sedation under spontaneous ventilation and continuous monitoring of oxygen saturation and blood pressure. Venous and arterial access was gained via the right femoral artery and vein using an 8 French sheath (St. Jude Medical, St. Paul, MN, USA). Mapping usually was first performed in the right ventricular outflow tract using a 3.5 mm ablation catheter (Thermocool®, ThermoCool Navistar®, Biosense-Webster, Diamond Bar, CA, USA; IBI Coolpath, SJM, St. Paul, MN, USA) Mapping was performed during spontaneous ectopy with or without orciprenalin to provoke ectopy. Mapping regions consisted of right and left ventricular outflow tract including the aortic root and its cusps in all patients. If right or left ventricular mapping did not reveal early activation (≤−20 ms) and/or no pacemap of at least 11/12 was achievable from right or left ventricular sites (10 mA; 2 ms) the procedure was continued on the left ventricular site. If earliest
Fig. 1. Mapping characteristics of VES originating from the distal coronary sinus (Cs). A: 12 lead ECG showing target VES. B: 12 lead ECG during pacemapping in the distal coronary sinus and (C) the LVOT. D: signals with mapping and 6 lead diagnostic catheter placed in the distal coronary sinus during target VES (from top to bottom): surface ECG; mapping catheter with uni- and bipolar lead; 6 lead diagnostic catheter; RVA catheter. E: corresponding fluoroscopic view of catheter positions during coronary angiography of the left coronary artery (RAO: right anterior oblique; LAO: left anterior oblique).
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activation and pacemap was unsatisfactory from the RV or LV and adjacent structures such as the aortic root and cusps as well, the procedure was continued in the GCV via the coronary sinus. Notably, the pacing output needed to be increased in some patients (up to 20 mA, 2.5 ms) during pacing in the GCV to achieve ventricular capture. Angiography of the coronary sinus and the GCV was performed if access was not easily obtainable to reveal any anatomical abnormalities. Coronary angiography was performed in all patients prior to ablation in 2 or more angulations (anterior/posterior 0° cranial/ caudal 0°; left anterior oblique 30° caudal 30°; right anterior oblique 30° cranial 30°; left anterior oblique 60° caudal 30°). Ablation was performed in a power controlled mode with a maximum temperature of 48 °C. The maximum output chosen was 40 W and less according to impedance readings at the actual catheter location if a distance of at least 5 mm was noted between the coronary arteries and the catheter tip in any of the angulations. Repeat angiography was performed if the catheter tip was within 5–15 mm distance of the coronary arterial system. Catheter ablation was considered successful if spontaneous ectopy was abolished after ablation. All procedural data were stored using a BARD® or Siemens/Sensis electrophysiology recording system for systematic review of the data. Twelve lead ECG was systematically analyzed to reveal characteristics for the GCV origin.
3. Results Between April 2009 and July 2011 117 consecutive patients underwent ablation of idiopathic VT and PVC in the University Hospital Münster or in the University Heart Center Hamburg-Eppendorf. In 14 patients (12%) the origin of the ectopy was localized in the GCV by mapping as described previously. The baseline characteristics of the patients included to this analysis are given in Table 1.
In all 14 patients, surface ECG showed early R/S transition or positive R wave in V1 (Fig. 1) in the chest leads and an inferior axis. However, a significant interpatient variability was also observed. Access to the GCV via the coronary sinus was obtainable in all patients. Mapping of spontaneous activity revealed the earliest ventricular activation with an average of 38.5 ± 8.6 ms to the earliest onset of surface QRS onset in the GCV. At this site, in 8 of 14 patients a perfect pacemap (12/12) was revealed (57%). In the remaining patients a 11/12 lead match was observed. In 3 patients pace capture of ventricular myocardium from the GCV was facilitated by increasing the pacing output to 20 mA and 2.5 ms. In 4 out of these 14 patients, ablation was not attempted due to close proximity to the coronary vessels (n = 3) or significant CAD progression (n = 1) as revealed during coronary angiography prior to RF application. In 3 of the remaining 10 patients, coronary artery stenosis was observed after the first RF applications (n=2) or high impedances prohibited effective RF application (n=1). In one patient, ablation was not successful despite effective RF energy delivery. In the remaining 6 patients (43%), ectopy was successfully ablated from the GCV. Coronary spam was observed in one patient after successful ablation and resolved after administration of nitroglycerin (Fig. 3). Out of the six patients, in whom initially successful ablation was performed, 1 had PVC recurrence during the follow-up.
Fig. 2. Successful ablation of VES from the distal coronary sinus. A: surface ECG (top) and ablation/map catheter intracardiac electrogram (bottom) during RF delivery. Cessation of the target VES is observed shortly after RF initiation. B: Corresponding fluoroscopic view of catheter position during coronary angiography of the left coronary artery (right anterior oblique).
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Fig. 3. Shown is the denominator for including patients into the study. Reasons prohibiting ablation or effective energy delivery in the GCV included (coronary artery disease) CAD progression, high impedance readings, proximity to the coronary vessels and coronary artery stenosis. In those patients (n = 3) in whom coronary artery stenosis was seen during or after RF application, coronary stenosis had resolved without sequela as documented during follow-up angiography, which was performed in one patient after 24 h (Fig. 4), in one patient after 4 days and in the remaining patient after 6 weeks.
Patients without successful ablation were put on antiarrhythmic drugs (betablocker, n = 2; class Ic, n = 2; both n = 2). Those patients on antiarrhythmic drugs still had PVCs during the follow-up.
4. Discussion In the present study, we were able to show that catheter ablation of PVC and VT arising from the ventricular outflow area may safely be
Fig. 4. Temporary coronary occlusion as a result of RF delivery in the distal coronary sinus (RAO: right anterior oblique; LAO: left anterior oblique). A: coronary angiogram of the left coronary artery with intact marginal branch (arrow) before RF delivery. B: Simultaneous coronary angiography during RF revealed an occlusion of the marginal branch. C: 24 h after RF delivery, the marginal branch showed reperfusion.
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ablated from the GCV. The present data further indicate that specific anatomic circumstances have to be considered performing ablation from the “epicardial” site even if sufficient distance from the coronary arteries is warranted. Catheter ablation of PVC and VT in patients without related structural heart disease is an established potential curative therapeutic approach. However, difficulties may be encountered considering the complex outflow tract anatomy with adjacent structures such as the coronary arteries and phrenic nerve as well as aortic root including cusps and the valvular apparatus [10]. Epicardial access may be necessary but may be limited even using a subxiphoidal epicardial approach. Therefore, “epicardial” mapping via the GCV should be considered during the procedure since access can easily be obtained and potential complications related to subxiphoidal puncture can be avoided [4]. Hints guiding towards an epicardial site of origin can also be obtained from the surface ECG as described by Vallès et al. [11]. Several limitations related to neighboring structures have to be considered when ablating from this site (Fig. 2): As seen in our present study, the narrow lumen of the GCV itself can be a limitation for RF delivery since it may prohibit from effective energy delivery and therefore obviate effective catheter ablation. However, energy can effectively be delivered if impedance limiters are turned off. In this setting, energy levels are often lower and may therefore limit procedural success. The most important risk when ablating from the epicardial surface is the laceration and resulting stenosis of the coronary arteries. Several pathophysiological mechanisms such as vasospasm, direct vessel trauma and secondary thromboembolism have been discussed to explain coronary artery damage occurring after catheter ablation [2]. It is important to stress that coronary artery damage may not be evident until several weeks after RF delivery [7]. This is potentially related to inflammatory processes evolving after coagulation necrosis resulting in fatty and fibrous intimal changes and therefore coronary artery stenosis or even plaque rupture and acute coronary syndrome. However, in most cases convective cooling seems to protect the coronary architecture from this effect, which explains the relatively low number of coronary injuries after RF application [3]. In animal models, it was shown that even in 5 mm distance from the coronary vessel endothelial changes might be observed after RF application. Sosa et al. [9] suggested that a minimum distance of 12 mm should be kept between the catheter tip and the coronary artery. In the presented patients, vasospasm may be discussed as a likely explanation for acute narrowing of coronary arteries. This hypothesis is supported by the fact that in one patient, stenosis was responsive to acute application of NTG. Postablation local edema serves as a potential alternative explanation. This hypothesis is supported by the observation that in two patients, a complete reversal was only observed during coronary angiography after a minimum of 24 h post-ablation. Recently, Viles-Gonzalez et al. reported on a swine model with RF energy application directly upon the coronary arteries [13]. The authors found that even if no acute stenosis was seen, important intimal changes could be found that may result in endothelial dysfunction and thereby lead to coronary artery stenosis later on after the ablation. One may therefore conclude that a minimum distance of 12 mm should be warranted along with repeat coronary angiography if a RF related coronary narrowing is suspected after ablation. It is important to realize that in patients, in whom RF application was effectively delivered in the GCV, the ectopy was successfully abolished in 6 out of 7. Therefore, reasonable acute outcome can be achieved, comparable to the outcome of endocardial ablation provided that effective energy application without premature abortion of the procedure can be achieved. During follow-up only one out of 6 patients had PVC/VT recurrence. Therefore, acute and mid-term acute success can be considered excellent, if RF application can successfully be performed. When approaching these focal ectopies, it is also crucial to carefully analyze 12 lead ECG morphology to get hints for potential ablation sites. In the ECGs analyzed for the present study, some ECG morphology criteria were revealed that appeared to be similar amongst patients,
12 lead ECG morphology may vary as shown in the ECGs of the patients included in our study. Thus, a GCV site of origin should be considered even if the ectopy does not show typical GCV pattern in the surface ECG. 4.1. Limitations Routine angiography of the coronary sinus and the GCV was not performed. Therefore, we are not able to provide data on potential thrombosis or stenosis of the GCV after RF application. 5. Conclusion The present study underscores that ectopy from the outflow tract region can be ablated from the GCV. We were able to show that special precautions regarding proximity to the coronaries have to be applied when ablating in the distal CS. Thus, in several cases close proximity to the coronary arteries prohibited effective RF delivery and in 3 patients diameter changes during RF occurred although these were transient. RF ablation for ectopy from the GCV resulted in good acute outcomes in this limited number of patients. Acknowledgments This study was supported by Interdisziplinäre Medizinische Forschung (IMF Po 12 06 07, to Christian Pott). Lars Eckardt holds the Osypka Professorship for Clinical and Experimental Electrophysiology. References [1] Baman TS, Ilg KJ, Gupta SK, et al. Mapping and ablation of epicardial idiopathic ventricular arrhythmias from within the coronary venous system. Circ Arrhythm Electrophysiol 2010;3:274–9. [2] Castaño A, Crawford T, Yamazaki M, Avula UM, Kalifa J. Coronary artery pathophysiology after radiofrequency catheter ablation: review and perspectives. Heart Rhythm 2011;8:1975–80. [3] D'Avila A, Gutierrez P, Scanavacca M, et al. Effects of radiofrequency pulses delivered in the vicinity of the coronary arteries: implications for nonsurgical transthoracic epicardial catheter ablation to treat ventricular tachycardia. Pacing Clin Electrophysiol 2002;25:1488–95. [4] Koruth JS, d'Avila A. Management of hemopericardium related to percutaneous epicardial access, mapping and ablation. Heart Rhythm 2011;8(10):1652–7. [5] Obel OA, d'Avila A, Neuzil P, Saad EB, Ruskin JN, Reddy VY. Ablation of left ventricular epicardial outflow tract tachycardia from the distal great cardiac vein. J Am Coll Cardiol 2006;48:1813–7. [6] Ribbing M, Wasmer K, Mönnig G, et al. Endocardial mapping of right ventricular outflow tract tachycardia using noncontact activation mapping. J Cardiovasc Electrophysiol 2003;14:602–8. [7] Roberts-Thomson KC, Steven D, Seiler J, et al. Coronary artery injury due to catheter ablation in adults: presentations and outcomes. Circulation 2009;120:1465–73. [8] Sacher F, Tedrow UB, Field ME, et al. Ventricular tachycardia ablation: evolution of patients and procedures over 8 years. Circ Arrhythm Electrophysiol 2008;1:153–61. [9] Sosa E, Scanavacca M, d'Avila A. Transthoracic epicardial catheter ablation to treat recurrent ventricular tachycardia. Curr Cardiol Rep 2001;3:451–8. [10] Steven D, Roberts-Thomson KC, Seiler J, et al. Ventricular tachycardia arising from the aortomitral continuity in structural heart disease: characteristics and therapeutic considerations for an anatomically challenging area of origin. Circ Arrhythm Electrophysiol 2009;2:660–6. [11] Vallès E, Bazan V, Marchlinski FE. ECG criteria to identify epicardial ventricular tachycardia in nonischemic cardiomyopathy. Circ Arrhythm Electrophysiol 2010;3:63–71. [12] Ventura R, Steven D, Klemm HU, et al. Decennial follow-up in patients with recurrent tachycardia originating from the right ventricular outflow tract: electrophysiologic characteristics and response to treatment. Eur Heart J 2007;28:2338–45. [13] Viles-Gonzalez JF, de Castro Miranda R, Scanavacca M, Sosa E, d'Avila A. Acute and chronic effects of epicardial radiofrequency applications delivered on epicardial coronary arteries. Circ Arrhythm Electrophysiol 2011;4(4):526–31. [14] Yamada T, McElderry HT, Doppalapudi H, et al. Idiopathic ventricular arrhythmias originating from the left ventricular summit: anatomic concepts relevant to ablation. Circ Arrhythm Electrophysiol 2010;3:616–23. [15] Zipes DP, Camm AJ, Borggrefe M, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (writing committee to develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation 2006;114:e385–484.
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Idiopathic ventricular outflow tract arrhythmias from the great cardiac vein: Challenges and risks of catheter ablation D. Steven a,⁎,1, C. Pott b,1, A. Bittner c, A. Sultan a, K. Wasmer b, B.A. Hoffmann a, J. Köbe b, I. Drewitz a, P. Milberg b, J. Lueker a, G. Mönnig b, H. Servatius a, S. Willems a, L. Eckardt b a b c
The University Heart Center Hamburg, Division of Cardiac Electrophysiology, Germany The University Hospital Münster, Division of Experimental and Clinical Electrophysiology, Department of Cardiology and Angiology, Germany The Pontificia Universidad Católica de Chile, Chile
a r t i c l e
i n f o
Article history: Received 3 June 2013 Received in revised form 21 August 2013 Accepted 27 September 2013 Available online 7 October 2013 Keywords: Catheter ablation Ventricular tachycardia Premature ventricular beats Coronary venous system Coronary artery system
a b s t r a c t Introduction: Catheter ablation for idiopathic ventricular arrhythmia is well established but epicardial origin, proximity to coronary arteries, and limited accessibility may complicate ablation from the venous system in particular from the great cardiac vein (GCV). Methods: Between April 2009 and October 2010 14 patients (56 ± 15 years; 9 male) out of a total group of 117 patients with idiopathic outflow tract tachycardias were included undergoing ablation for idiopathic VT or premature ventricular contractions (PVC) originating from GCV. All patients in whom the PVC arose from the GCV were subject to the study. In these patients angiography of the left coronary system was performed with the ablation catheter at the site of earliest activation. Results: Successful ablation was performed in 6/14 (43%) and long-term success was achieved in 5/14 (36%) patients. In 4/14 patients (28.6%) ablation was not performed. In another 4 patients (26.7%), ablation did not abolish the PVC/VT. In the majority, the anatomical proximity to the left coronary system prohibited effective RF application. In 3 patients RF application resulted in a coronary spasm with complete regression as revealed in repeat coronary angiography. Conclusion: A relevant proportion idiopathic VT/PVC can safely be ablated from the GCV without significant permanent coronary artery stenosis after RF application. Our data furthermore demonstrate that damage to the coronary artery system is likely to be transient. © 2013 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Catheter ablation of sustained ventricular tachycardia (VT) and premature ventricular capture beats (PVC) is an established therapy option especially in patients without structural heart disease [8,15]. High longterm success rates are achievable and the majority of patients with PVC arising from the right or left ventricular outflow tract can successfully be treated using radiofrequency (RF) ablation from the endocardium [6,12]. However, in some patients focal ectopy may arise from the pericardial space, especially the left ventricular summit that in most cases may be reached from the venous cardiac system, namely the great cardiac vein (GCV). It has been shown that epicardial ablation using a subxiphoidal access is also feasible to treat these arrhythmias using radiofrequency (RF) ablation [1,5,11,14]. ⁎ Corresponding author at: Universitäres Herzzentrum Hamburg, Martinistr. 52, 20251 Hamburg, Germany. Tel.: +49 40 7410 54120; fax: +49 40 7410 54125. 1 Both authors contributed equally to this work. 0167-5273/$ – see front matter © 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijcard.2013.09.008
The least invasive access to target epicardial outflow foci is obtained via the venous cardiac system. In this setting, it is important to be aware of potential limitations that may be encountered when aiming for outflow tract VT/PVC ablation from the GCV. First, the epicardial access may not be easily achievable due to anatomic consideration, e.g. a Thebesian valve or small diameter vessels. Second, as in most cases radiofrequency is used to aim for these foci, energy delivery may be limited due to high impendances and limited irrigation flow. Third and potentially most importantly, the close proximity of the GCV to the coronary artery system and other anatomical structures such as the phrenic nerve may pose limitations for RF application in the GCV. Despite the fact that coronary artery injury has been described to be a rare entity (0.09%) during catheter ablation of atrial or ventricular tachycardia this potentially devastating complication has to be kept in mind, especially when ablating in the coronary sinus [7]. The aim of the present study was to evaluate the possibilities and challenges using RF energy to target these foci from the epicardium and to clarify the associated risks when ablating in close proximity to the coronary artery system.
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Table 1 Baseline characteristics of patients included to the study (m = male; f = female; DCM = dilative cardiomyopathy; ICM = ischemic cardiomyopathy; PVC = premature ventricular capture beat, nsVT = non-sustained ventricular tachycardia).
#1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14
Gender
Age
Structural heart disease
VT/PVC
Ablation attempted
Effective energy application
Primary success
Long-term success
M F M F M M F F M M M F M F
75 49 28 62 73 48 39 68 73 56 57 30 56 54
ICM No No No No No No No No No DCM No No No
PVC PVC PVC PVC PVC PVC PVC PVC PVC PVC nsVT PVC nsVT PVC
No Yes Yes No No Yes Yes Yes No Yes Yes Yes Yes Yes
No Yes Yes No No No Yes Yes No Yes Yes Yes No No
No Yes Yes No No No Yes Yes No Yes No Yes No No
No Yes Yes No No No Yes Yes No Yes No No No No
2. Methods Patients undergoing catheter ablation for symptomatic idiopathic VT or PVC were included in two high volume centers (University Hospital Hamburg-Eppendorf and University Hospital Münster) if the following criteria were met: 1. Typical 12 lead ECG outflow tract morphology (inferior axis, positive R waves in leads II and III) 2. Ectopy originating from the outflow tract area with the earliest local activation time in the GCV (after GCV leaves the interventricular groove and enters the mitral valvular level) after mapping of the RVOT and/or left ventricular cavity and outflow tract area 3. Absence of anatomical substrate for VT 4. Attempt to abolish VT/PVC using RF energy from the GCV 5. Coronary angiography before and after ablation in the GCV
Two patients had additional structural heart disease (dilative cardiomyopathy, n = 1; ischemic cardiomyopathy, n = 1). All patients gave written informed consent and underwent conscious sedation under spontaneous ventilation and continuous monitoring of oxygen saturation and blood pressure. Venous and arterial access was gained via the right femoral artery and vein using an 8 French sheath (St. Jude Medical, St. Paul, MN, USA). Mapping usually was first performed in the right ventricular outflow tract using a 3.5 mm ablation catheter (Thermocool®, ThermoCool Navistar®, Biosense-Webster, Diamond Bar, CA, USA; IBI Coolpath, SJM, St. Paul, MN, USA) Mapping was performed during spontaneous ectopy with or without orciprenalin to provoke ectopy. Mapping regions consisted of right and left ventricular outflow tract including the aortic root and its cusps in all patients. If right or left ventricular mapping did not reveal early activation (≤−20 ms) and/or no pacemap of at least 11/12 was achievable from right or left ventricular sites (10 mA; 2 ms) the procedure was continued on the left ventricular site. If earliest
Fig. 1. Mapping characteristics of VES originating from the distal coronary sinus (Cs). A: 12 lead ECG showing target VES. B: 12 lead ECG during pacemapping in the distal coronary sinus and (C) the LVOT. D: signals with mapping and 6 lead diagnostic catheter placed in the distal coronary sinus during target VES (from top to bottom): surface ECG; mapping catheter with uni- and bipolar lead; 6 lead diagnostic catheter; RVA catheter. E: corresponding fluoroscopic view of catheter positions during coronary angiography of the left coronary artery (RAO: right anterior oblique; LAO: left anterior oblique).
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activation and pacemap was unsatisfactory from the RV or LV and adjacent structures such as the aortic root and cusps as well, the procedure was continued in the GCV via the coronary sinus. Notably, the pacing output needed to be increased in some patients (up to 20 mA, 2.5 ms) during pacing in the GCV to achieve ventricular capture. Angiography of the coronary sinus and the GCV was performed if access was not easily obtainable to reveal any anatomical abnormalities. Coronary angiography was performed in all patients prior to ablation in 2 or more angulations (anterior/posterior 0° cranial/ caudal 0°; left anterior oblique 30° caudal 30°; right anterior oblique 30° cranial 30°; left anterior oblique 60° caudal 30°). Ablation was performed in a power controlled mode with a maximum temperature of 48 °C. The maximum output chosen was 40 W and less according to impedance readings at the actual catheter location if a distance of at least 5 mm was noted between the coronary arteries and the catheter tip in any of the angulations. Repeat angiography was performed if the catheter tip was within 5–15 mm distance of the coronary arterial system. Catheter ablation was considered successful if spontaneous ectopy was abolished after ablation. All procedural data were stored using a BARD® or Siemens/Sensis electrophysiology recording system for systematic review of the data. Twelve lead ECG was systematically analyzed to reveal characteristics for the GCV origin.
3. Results Between April 2009 and July 2011 117 consecutive patients underwent ablation of idiopathic VT and PVC in the University Hospital Münster or in the University Heart Center Hamburg-Eppendorf. In 14 patients (12%) the origin of the ectopy was localized in the GCV by mapping as described previously. The baseline characteristics of the patients included to this analysis are given in Table 1.
In all 14 patients, surface ECG showed early R/S transition or positive R wave in V1 (Fig. 1) in the chest leads and an inferior axis. However, a significant interpatient variability was also observed. Access to the GCV via the coronary sinus was obtainable in all patients. Mapping of spontaneous activity revealed the earliest ventricular activation with an average of 38.5 ± 8.6 ms to the earliest onset of surface QRS onset in the GCV. At this site, in 8 of 14 patients a perfect pacemap (12/12) was revealed (57%). In the remaining patients a 11/12 lead match was observed. In 3 patients pace capture of ventricular myocardium from the GCV was facilitated by increasing the pacing output to 20 mA and 2.5 ms. In 4 out of these 14 patients, ablation was not attempted due to close proximity to the coronary vessels (n = 3) or significant CAD progression (n = 1) as revealed during coronary angiography prior to RF application. In 3 of the remaining 10 patients, coronary artery stenosis was observed after the first RF applications (n=2) or high impedances prohibited effective RF application (n=1). In one patient, ablation was not successful despite effective RF energy delivery. In the remaining 6 patients (43%), ectopy was successfully ablated from the GCV. Coronary spam was observed in one patient after successful ablation and resolved after administration of nitroglycerin (Fig. 3). Out of the six patients, in whom initially successful ablation was performed, 1 had PVC recurrence during the follow-up.
Fig. 2. Successful ablation of VES from the distal coronary sinus. A: surface ECG (top) and ablation/map catheter intracardiac electrogram (bottom) during RF delivery. Cessation of the target VES is observed shortly after RF initiation. B: Corresponding fluoroscopic view of catheter position during coronary angiography of the left coronary artery (right anterior oblique).
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Fig. 3. Shown is the denominator for including patients into the study. Reasons prohibiting ablation or effective energy delivery in the GCV included (coronary artery disease) CAD progression, high impedance readings, proximity to the coronary vessels and coronary artery stenosis. In those patients (n = 3) in whom coronary artery stenosis was seen during or after RF application, coronary stenosis had resolved without sequela as documented during follow-up angiography, which was performed in one patient after 24 h (Fig. 4), in one patient after 4 days and in the remaining patient after 6 weeks.
Patients without successful ablation were put on antiarrhythmic drugs (betablocker, n = 2; class Ic, n = 2; both n = 2). Those patients on antiarrhythmic drugs still had PVCs during the follow-up.
4. Discussion In the present study, we were able to show that catheter ablation of PVC and VT arising from the ventricular outflow area may safely be
Fig. 4. Temporary coronary occlusion as a result of RF delivery in the distal coronary sinus (RAO: right anterior oblique; LAO: left anterior oblique). A: coronary angiogram of the left coronary artery with intact marginal branch (arrow) before RF delivery. B: Simultaneous coronary angiography during RF revealed an occlusion of the marginal branch. C: 24 h after RF delivery, the marginal branch showed reperfusion.
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ablated from the GCV. The present data further indicate that specific anatomic circumstances have to be considered performing ablation from the “epicardial” site even if sufficient distance from the coronary arteries is warranted. Catheter ablation of PVC and VT in patients without related structural heart disease is an established potential curative therapeutic approach. However, difficulties may be encountered considering the complex outflow tract anatomy with adjacent structures such as the coronary arteries and phrenic nerve as well as aortic root including cusps and the valvular apparatus [10]. Epicardial access may be necessary but may be limited even using a subxiphoidal epicardial approach. Therefore, “epicardial” mapping via the GCV should be considered during the procedure since access can easily be obtained and potential complications related to subxiphoidal puncture can be avoided [4]. Hints guiding towards an epicardial site of origin can also be obtained from the surface ECG as described by Vallès et al. [11]. Several limitations related to neighboring structures have to be considered when ablating from this site (Fig. 2): As seen in our present study, the narrow lumen of the GCV itself can be a limitation for RF delivery since it may prohibit from effective energy delivery and therefore obviate effective catheter ablation. However, energy can effectively be delivered if impedance limiters are turned off. In this setting, energy levels are often lower and may therefore limit procedural success. The most important risk when ablating from the epicardial surface is the laceration and resulting stenosis of the coronary arteries. Several pathophysiological mechanisms such as vasospasm, direct vessel trauma and secondary thromboembolism have been discussed to explain coronary artery damage occurring after catheter ablation [2]. It is important to stress that coronary artery damage may not be evident until several weeks after RF delivery [7]. This is potentially related to inflammatory processes evolving after coagulation necrosis resulting in fatty and fibrous intimal changes and therefore coronary artery stenosis or even plaque rupture and acute coronary syndrome. However, in most cases convective cooling seems to protect the coronary architecture from this effect, which explains the relatively low number of coronary injuries after RF application [3]. In animal models, it was shown that even in 5 mm distance from the coronary vessel endothelial changes might be observed after RF application. Sosa et al. [9] suggested that a minimum distance of 12 mm should be kept between the catheter tip and the coronary artery. In the presented patients, vasospasm may be discussed as a likely explanation for acute narrowing of coronary arteries. This hypothesis is supported by the fact that in one patient, stenosis was responsive to acute application of NTG. Postablation local edema serves as a potential alternative explanation. This hypothesis is supported by the observation that in two patients, a complete reversal was only observed during coronary angiography after a minimum of 24 h post-ablation. Recently, Viles-Gonzalez et al. reported on a swine model with RF energy application directly upon the coronary arteries [13]. The authors found that even if no acute stenosis was seen, important intimal changes could be found that may result in endothelial dysfunction and thereby lead to coronary artery stenosis later on after the ablation. One may therefore conclude that a minimum distance of 12 mm should be warranted along with repeat coronary angiography if a RF related coronary narrowing is suspected after ablation. It is important to realize that in patients, in whom RF application was effectively delivered in the GCV, the ectopy was successfully abolished in 6 out of 7. Therefore, reasonable acute outcome can be achieved, comparable to the outcome of endocardial ablation provided that effective energy application without premature abortion of the procedure can be achieved. During follow-up only one out of 6 patients had PVC/VT recurrence. Therefore, acute and mid-term acute success can be considered excellent, if RF application can successfully be performed. When approaching these focal ectopies, it is also crucial to carefully analyze 12 lead ECG morphology to get hints for potential ablation sites. In the ECGs analyzed for the present study, some ECG morphology criteria were revealed that appeared to be similar amongst patients,
12 lead ECG morphology may vary as shown in the ECGs of the patients included in our study. Thus, a GCV site of origin should be considered even if the ectopy does not show typical GCV pattern in the surface ECG. 4.1. Limitations Routine angiography of the coronary sinus and the GCV was not performed. Therefore, we are not able to provide data on potential thrombosis or stenosis of the GCV after RF application. 5. Conclusion The present study underscores that ectopy from the outflow tract region can be ablated from the GCV. We were able to show that special precautions regarding proximity to the coronaries have to be applied when ablating in the distal CS. Thus, in several cases close proximity to the coronary arteries prohibited effective RF delivery and in 3 patients diameter changes during RF occurred although these were transient. RF ablation for ectopy from the GCV resulted in good acute outcomes in this limited number of patients. Acknowledgments This study was supported by Interdisziplinäre Medizinische Forschung (IMF Po 12 06 07, to Christian Pott). Lars Eckardt holds the Osypka Professorship for Clinical and Experimental Electrophysiology. References [1] Baman TS, Ilg KJ, Gupta SK, et al. Mapping and ablation of epicardial idiopathic ventricular arrhythmias from within the coronary venous system. Circ Arrhythm Electrophysiol 2010;3:274–9. [2] Castaño A, Crawford T, Yamazaki M, Avula UM, Kalifa J. Coronary artery pathophysiology after radiofrequency catheter ablation: review and perspectives. Heart Rhythm 2011;8:1975–80. [3] D'Avila A, Gutierrez P, Scanavacca M, et al. Effects of radiofrequency pulses delivered in the vicinity of the coronary arteries: implications for nonsurgical transthoracic epicardial catheter ablation to treat ventricular tachycardia. Pacing Clin Electrophysiol 2002;25:1488–95. [4] Koruth JS, d'Avila A. Management of hemopericardium related to percutaneous epicardial access, mapping and ablation. Heart Rhythm 2011;8(10):1652–7. [5] Obel OA, d'Avila A, Neuzil P, Saad EB, Ruskin JN, Reddy VY. Ablation of left ventricular epicardial outflow tract tachycardia from the distal great cardiac vein. J Am Coll Cardiol 2006;48:1813–7. [6] Ribbing M, Wasmer K, Mönnig G, et al. Endocardial mapping of right ventricular outflow tract tachycardia using noncontact activation mapping. J Cardiovasc Electrophysiol 2003;14:602–8. [7] Roberts-Thomson KC, Steven D, Seiler J, et al. Coronary artery injury due to catheter ablation in adults: presentations and outcomes. Circulation 2009;120:1465–73. [8] Sacher F, Tedrow UB, Field ME, et al. Ventricular tachycardia ablation: evolution of patients and procedures over 8 years. Circ Arrhythm Electrophysiol 2008;1:153–61. [9] Sosa E, Scanavacca M, d'Avila A. Transthoracic epicardial catheter ablation to treat recurrent ventricular tachycardia. Curr Cardiol Rep 2001;3:451–8. [10] Steven D, Roberts-Thomson KC, Seiler J, et al. Ventricular tachycardia arising from the aortomitral continuity in structural heart disease: characteristics and therapeutic considerations for an anatomically challenging area of origin. Circ Arrhythm Electrophysiol 2009;2:660–6. [11] Vallès E, Bazan V, Marchlinski FE. ECG criteria to identify epicardial ventricular tachycardia in nonischemic cardiomyopathy. Circ Arrhythm Electrophysiol 2010;3:63–71. [12] Ventura R, Steven D, Klemm HU, et al. Decennial follow-up in patients with recurrent tachycardia originating from the right ventricular outflow tract: electrophysiologic characteristics and response to treatment. Eur Heart J 2007;28:2338–45. [13] Viles-Gonzalez JF, de Castro Miranda R, Scanavacca M, Sosa E, d'Avila A. Acute and chronic effects of epicardial radiofrequency applications delivered on epicardial coronary arteries. Circ Arrhythm Electrophysiol 2011;4(4):526–31. [14] Yamada T, McElderry HT, Doppalapudi H, et al. Idiopathic ventricular arrhythmias originating from the left ventricular summit: anatomic concepts relevant to ablation. Circ Arrhythm Electrophysiol 2010;3:616–23. [15] Zipes DP, Camm AJ, Borggrefe M, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (writing committee to develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation 2006;114:e385–484.
