tACC Val . 18, No. 7 December1991.1719-0
1759
Editoral Comment
Radiofrequency Catheter Ablation of the AV Node* PABLO DENES, MD, FACC Sr . Paid. Minnesota
Rad ofrequency ablation used for the treatment of arrhythmiss is a rapidly evolving technique of interventional cardiology (I). Its current clinical application for the treatment of symptomatic supraventricular tachycardia appears to be highly effective and reasonably safe (2-4): in fact, radiofrequency ablation is likely to become the treatment of choice for patients with this condition and is a r'ilestone in the long quest for the ideal treatment of supraventricular arrhythmias . Progress in treatment of supraventricular arrhythmias . Our current situation is the result of past achievements . We learned from clinical electrophysiology the mechanism of supraventricular arrhythmias in humans (5) . Simultaneouly . techniques were developed to map the conduction system and to localize the anomalous atrioventricular (AV) connections and the site of reentry or ectopic foci, or both . Antiarrhythmic surgery was introduced to cure the arrhythmias that in the past could only be palliated by drugs 16) . Early attempts to treat supraventricular arrhylhmias surgically involved interruption of the normal AV conduction system . Improved and more accurate mapping resulted in further refinement of surgical techniques . Other therapies, such as antitachycardia pacing and elcctrophysiologically guided antiarrhythmic therapy, evolved in parallel because the surgical techniques, although they are highly successful and have a low mortality rate, are still associated with considerable morbidity and high cost . Direct-current catheter ablation. The last decade withnessed an explosive growth in the use of interventional cardiology . The treatment of coronary artery disease with percutaneous coronary angioplasty resulted in a major shift in the indication for and use of coronary bypass surgery . A similarly important development is the treatment of supraventricular tachycardia with the use of perculaneous catheter ablation techniques . In treating this arrhythmia . catheter ablation can he used to control heart rate, as in patients with atria) fibrillation, or to attempt to cure the
'Editorials published in Jnu naI -I It, A,,,, an,, ON—- ,t C,dwh,v, Out the views of the raison and do not aecasarily represent the vices of JACC or the .American Cnllepe of Cariolngy . From ate Secdun of Cardiology . St. Paul Ramsey Stadicat Center .
Rum ry Clinic, St . Paul Slinnewta . Address for r u: Pabla nor,,, Stn . Section of r.rdialogy . Se Part Medical Ramsey Ram- Clime . 6+11 Jaokrua Street St- Paul . Minnesors 55101, %1991
by
th, American
Can— if Card la,
arrhythmia by ablation or by significant modification of the reentrant pathways. as in AV node or AV reentry (accessory pathways) (Ii . Heart rt.:e control requires the use of a permanent pacemaker, whereas the modification of reentrant pathways is curative and does not affect the normal AV conduction system . Direct-current ablation has been used to interrupt AV conduction and control heart rate in patients with drugresistant supraventricular tachycacdia (7) . This approach employs a conventional defibrillator to deliver a high energy shock. sometimes >2 .000 V . to the endocardium. This intense current causes barotrauma, heat, lighting and an electrical gradient, some or all of which result in local tissue damage . The technique produces relatively extensive damage (both beneath and on the surface) end is associated with many potential complications, such as cardiac rupture, ventricular dysfunction, coronary spasm, myocardial infarction and ventricular arrhylhmias. The procedure is painful and has to be performed with the patient under general anesthesia. These significant limitations of the technique have curtailed its widespread use in the treatment of supraventricular tachvcardia. Radiofrequency catheter ablation . Radiofrequency electrical energy is much safer (2) . It uses low voltage energy (40 to 60 V), does not produce barotrauma, does not require general anesthesia and graded amounts of energy can be delivered to a specific area . Although radiofrequency energy has been used for many years, its current application for the specific treatment of supraventricular arrhythmias awaited advances in mapping techniques and ablation catheter technology . Recent studies (3,4) have reported an impressive success rate (92% to 99%) for radiofrequency ablation in the treatment of patients with Wolff-Parkinson-white syndrome and other forms of reentrant supraventricular arrhythmias . This high success rate is in part related to the ability to map and record anomalous pathway potentials before ablation in the great majority of patients (approximately 90%) (4). The present study . In this issue of the Journal, YoungLai-Wah et al . (8) present an observational study of 32 patients undergoing radiofrequency catheter ablation of the AV node, The high success rate and low incidence of complications (none directly related to ablation) are impressive. The high success rate is attributable to improved mapping techniques and a new deflectable catheter with a large (4 mm) distal electrode . However, patients with AV node reentry and ectopic atrial tachycardia currently undergo selective ablation of the reentrant pathway and ectopic foci rather than interruption of AV conduction . We do nz' have information about the AV node conduction characteristics of the 19 patients who were in sinus rhythm at the time of ablation . This information might help us to understand and interpret the reasons for rapid AN, conduction in these patients . We have little information on the anatomic location and size of the AV node in those patients with accelerated AV node conduction. Radiofrequency ablation not only is 0775-1a97ro155 .50
1701>
or NIS EDITORIAL COMMENT
therapeutic, but also may provide information regarding the pmhophysiologic aspects of the arrhythmins in these patients . Certainly . in AV node reentry the use of surgical and radiofrequency ablation has opened new horizons for investigating the mechanism of this reentrant arrhythmia . In this study half of the patients had good left ventricular function without underlying heart disease . Such patients with "lone" atria) fibrillation have a good prognosis, and the prospect of lifelong use of a permanent pacemaker has to be considered when the decision for ablation is made . It is also a question whether similarly excellent results can be obtained with ablation in patients with underlying heart disease, impaired left ventricular function or atria) fibrillation . Conclusions. Although the initial results of radiofrequency catheter ablation of the AV node are highly encouraging, the data come from specialized centers with substantial expertise and may not be reproducible by others . The long-term efficacy and safety of the procedure in relation to vascular injury . X-ray exposure and new ventricular orrhythmias need to be established . Catheter ablation procedares should be performed only at specific centers b, an electrophysiologist trained in the pathophysiology of cardiac arrhylhmio ,. .
JACC Vol . m. Na. 7 D-nrhF r 1"1 :1711-60
References I . Scheinman MM . Lake MM. DiMarca 1 . Plumb V . Current rule of cathemr ablative procedures in pancale with cardiac arrhythmiac- a report far health professionals from the Subcommittee an Eleerroamdiography and ElecnophysiolaW'. American Hear Association . Circulation 1991 :83 : 214h-53, 2 . Haunt; SK .Advaneesinapplication, ofrudiofrequencycurrent Iaeatheler ablation therapy . PACE 1991:14:28-42. 3 . Calkins H. Souca J . El-Alassi R . el al . Diagnosis and care of the Wolf. Parkinson-White syndrome or paroxysmal supraventriculur tachycardius during a single electrophysiologic lee . N One J Med 1991 :324 : 1612-8 . 4 . Jack,,, WM . Wang X . Rate., Kl . el al. Catheter ablation of accessory aviuvemricular pathways (Woltf-Parkinson-Whim syndrome) by radiafre, gacncy came. . N Fud J Med pri1 :724:I6U5-I I . 5 . Durrer D . Schno I .. Schuilenburg RM. Wellens HJI . Thereat, of maemm beats in the initiation and lamination of eapravemricular inch ycurdia in the Wolfi-Pmkim,anWhile syndrome. Circulation 1967 :36:644-52 . 6, Cue 11. . Gullaeher tJ . Cain ME . Experience with I I8 consecutive patients undergoing operation for the Wa1R-i'arkinsoo-While syndrome . J Thora Cardioe'asc Sure 1985!1x :490-501 . 7 . Gallagher 1J. Svensen RH . Kasell 1H. st al . Catheter technique for closed-chest ablation of the alriaacnlricular conduction system : n therapeutic alterative for the treatment or refractory supraventricular tachycartia. N F gl l Med 1992:306:194-201) . 8 . Yeung.Lai-Wah IA, Alison IF. Lenergan L . Mohama R . Leather R. Kem CR . High sucres, rate of atriovennicular node ablation with radiofrequency energy. I Am Coll Cerdiol 1991,18 :1753_8.
1759
Editoral Comment
Radiofrequency Catheter Ablation of the AV Node* PABLO DENES, MD, FACC Sr . Paid. Minnesota
Rad ofrequency ablation used for the treatment of arrhythmiss is a rapidly evolving technique of interventional cardiology (I). Its current clinical application for the treatment of symptomatic supraventricular tachycardia appears to be highly effective and reasonably safe (2-4): in fact, radiofrequency ablation is likely to become the treatment of choice for patients with this condition and is a r'ilestone in the long quest for the ideal treatment of supraventricular arrhythmias . Progress in treatment of supraventricular arrhythmias . Our current situation is the result of past achievements . We learned from clinical electrophysiology the mechanism of supraventricular arrhythmias in humans (5) . Simultaneouly . techniques were developed to map the conduction system and to localize the anomalous atrioventricular (AV) connections and the site of reentry or ectopic foci, or both . Antiarrhythmic surgery was introduced to cure the arrhythmias that in the past could only be palliated by drugs 16) . Early attempts to treat supraventricular arrhylhmias surgically involved interruption of the normal AV conduction system . Improved and more accurate mapping resulted in further refinement of surgical techniques . Other therapies, such as antitachycardia pacing and elcctrophysiologically guided antiarrhythmic therapy, evolved in parallel because the surgical techniques, although they are highly successful and have a low mortality rate, are still associated with considerable morbidity and high cost . Direct-current catheter ablation. The last decade withnessed an explosive growth in the use of interventional cardiology . The treatment of coronary artery disease with percutaneous coronary angioplasty resulted in a major shift in the indication for and use of coronary bypass surgery . A similarly important development is the treatment of supraventricular tachycardia with the use of perculaneous catheter ablation techniques . In treating this arrhythmia . catheter ablation can he used to control heart rate, as in patients with atria) fibrillation, or to attempt to cure the
'Editorials published in Jnu naI -I It, A,,,, an,, ON—- ,t C,dwh,v, Out the views of the raison and do not aecasarily represent the vices of JACC or the .American Cnllepe of Cariolngy . From ate Secdun of Cardiology . St. Paul Ramsey Stadicat Center .
Rum ry Clinic, St . Paul Slinnewta . Address for r u: Pabla nor,,, Stn . Section of r.rdialogy . Se Part Medical Ramsey Ram- Clime . 6+11 Jaokrua Street St- Paul . Minnesors 55101, %1991
by
th, American
Can— if Card la,
arrhythmia by ablation or by significant modification of the reentrant pathways. as in AV node or AV reentry (accessory pathways) (Ii . Heart rt.:e control requires the use of a permanent pacemaker, whereas the modification of reentrant pathways is curative and does not affect the normal AV conduction system . Direct-current ablation has been used to interrupt AV conduction and control heart rate in patients with drugresistant supraventricular tachycacdia (7) . This approach employs a conventional defibrillator to deliver a high energy shock. sometimes >2 .000 V . to the endocardium. This intense current causes barotrauma, heat, lighting and an electrical gradient, some or all of which result in local tissue damage . The technique produces relatively extensive damage (both beneath and on the surface) end is associated with many potential complications, such as cardiac rupture, ventricular dysfunction, coronary spasm, myocardial infarction and ventricular arrhylhmias. The procedure is painful and has to be performed with the patient under general anesthesia. These significant limitations of the technique have curtailed its widespread use in the treatment of supraventricular tachvcardia. Radiofrequency catheter ablation . Radiofrequency electrical energy is much safer (2) . It uses low voltage energy (40 to 60 V), does not produce barotrauma, does not require general anesthesia and graded amounts of energy can be delivered to a specific area . Although radiofrequency energy has been used for many years, its current application for the specific treatment of supraventricular arrhythmias awaited advances in mapping techniques and ablation catheter technology . Recent studies (3,4) have reported an impressive success rate (92% to 99%) for radiofrequency ablation in the treatment of patients with Wolff-Parkinson-white syndrome and other forms of reentrant supraventricular arrhythmias . This high success rate is in part related to the ability to map and record anomalous pathway potentials before ablation in the great majority of patients (approximately 90%) (4). The present study . In this issue of the Journal, YoungLai-Wah et al . (8) present an observational study of 32 patients undergoing radiofrequency catheter ablation of the AV node, The high success rate and low incidence of complications (none directly related to ablation) are impressive. The high success rate is attributable to improved mapping techniques and a new deflectable catheter with a large (4 mm) distal electrode . However, patients with AV node reentry and ectopic atrial tachycardia currently undergo selective ablation of the reentrant pathway and ectopic foci rather than interruption of AV conduction . We do nz' have information about the AV node conduction characteristics of the 19 patients who were in sinus rhythm at the time of ablation . This information might help us to understand and interpret the reasons for rapid AN, conduction in these patients . We have little information on the anatomic location and size of the AV node in those patients with accelerated AV node conduction. Radiofrequency ablation not only is 0775-1a97ro155 .50
1701>
or NIS EDITORIAL COMMENT
therapeutic, but also may provide information regarding the pmhophysiologic aspects of the arrhythmins in these patients . Certainly . in AV node reentry the use of surgical and radiofrequency ablation has opened new horizons for investigating the mechanism of this reentrant arrhythmia . In this study half of the patients had good left ventricular function without underlying heart disease . Such patients with "lone" atria) fibrillation have a good prognosis, and the prospect of lifelong use of a permanent pacemaker has to be considered when the decision for ablation is made . It is also a question whether similarly excellent results can be obtained with ablation in patients with underlying heart disease, impaired left ventricular function or atria) fibrillation . Conclusions. Although the initial results of radiofrequency catheter ablation of the AV node are highly encouraging, the data come from specialized centers with substantial expertise and may not be reproducible by others . The long-term efficacy and safety of the procedure in relation to vascular injury . X-ray exposure and new ventricular orrhythmias need to be established . Catheter ablation procedares should be performed only at specific centers b, an electrophysiologist trained in the pathophysiology of cardiac arrhylhmio ,. .
JACC Vol . m. Na. 7 D-nrhF r 1"1 :1711-60
References I . Scheinman MM . Lake MM. DiMarca 1 . Plumb V . Current rule of cathemr ablative procedures in pancale with cardiac arrhythmiac- a report far health professionals from the Subcommittee an Eleerroamdiography and ElecnophysiolaW'. American Hear Association . Circulation 1991 :83 : 214h-53, 2 . Haunt; SK .Advaneesinapplication, ofrudiofrequencycurrent Iaeatheler ablation therapy . PACE 1991:14:28-42. 3 . Calkins H. Souca J . El-Alassi R . el al . Diagnosis and care of the Wolf. Parkinson-White syndrome or paroxysmal supraventriculur tachycardius during a single electrophysiologic lee . N One J Med 1991 :324 : 1612-8 . 4 . Jack,,, WM . Wang X . Rate., Kl . el al. Catheter ablation of accessory aviuvemricular pathways (Woltf-Parkinson-Whim syndrome) by radiafre, gacncy came. . N Fud J Med pri1 :724:I6U5-I I . 5 . Durrer D . Schno I .. Schuilenburg RM. Wellens HJI . Thereat, of maemm beats in the initiation and lamination of eapravemricular inch ycurdia in the Wolfi-Pmkim,anWhile syndrome. Circulation 1967 :36:644-52 . 6, Cue 11. . Gullaeher tJ . Cain ME . Experience with I I8 consecutive patients undergoing operation for the Wa1R-i'arkinsoo-While syndrome . J Thora Cardioe'asc Sure 1985!1x :490-501 . 7 . Gallagher 1J. Svensen RH . Kasell 1H. st al . Catheter technique for closed-chest ablation of the alriaacnlricular conduction system : n therapeutic alterative for the treatment or refractory supraventricular tachycartia. N F gl l Med 1992:306:194-201) . 8 . Yeung.Lai-Wah IA, Alison IF. Lenergan L . Mohama R . Leather R. Kem CR . High sucres, rate of atriovennicular node ablation with radiofrequency energy. I Am Coll Cerdiol 1991,18 :1753_8.
