Surgery of Tachyarrhythmia: Intracardiac Closed Heart Cryoablation JURGIS J. BREDIKIS and AUDRIUS J. BREDIKIS From the Kaunas Arrhythmia Surgery Center, Kaunas, Lithuania
BREDIKIS, J. J., ET AL.: Surgery of Tachyarrhythmia: Intracardiac Closed Heart Cryoablation. Closed heart surgery without the use of cardiopulmonary bypass (CPB) is one of the trends of surgical treatment of tachyarrhythmias. Having rich experience of epicardial cryoablation, the authors introduced the original technique of intracardiac cryoablation. They have demonstrated the feasibility of creation of complete AV block in patients with supraventricular tachycardias by AV node-His-bundle cryoablation, elimaintion of AV junctional (“nodal”) tachycardia by perinodal cryoablation, cryoablation of septa1 and paraseptal left posterior AV accessory pathways and ectopic foci in atrial septum, complete or partial cryoisolation or cryofragmentation of the atria in patients with atrial flutter and/or fibrillation, and cryoablation or arrhythmogenic zones in ventricles. Good results (arrhythmia-free patients) were obtained in 82%-100%. Cryoablation on the closed heart without the use of CPB has the following advantages: (a) the possibility of continuous monitoring of cardiac electrical activity during the operation; (b) ablation efficacy control; and (c) dimished trauma and little risk of surgical intervention. [PACE, Vol. 13, December, Part I1 1990) tachycardia, intracardiac cryoablation
Introduction Arrhythmia surgery is the most important trend of cardiovascular surgery that has been intensively developed for the last decade. This “surgical breakthrough” in arrhythmia treatment is particularly due to better understanding of underlying electrophysiological mechanisms and anatomical substrates of tachycardias, as well as to progress in clinical cardiac electrophysiology and computer-assisted intraoperative mapping. On the other hand, the implementation of new methods such as thermocoagulation, electrical fulguration, cryoablation, and laser or microwave techniques further facilitated surgical destruction of arrhythmogenic substrates. There are three main ways of antitachycardia surgery. The first one is the open heart surgery with the use of cardiopulmonary bypass (CPB). The second is the external (epicardial) closed
Address for reprints: Professor Jurgis J. Bredikis, M.D., Kaunas Arrhythmia Surgery Center, Z. Januskevicius 2.. 233000, Kaunas, Lithuania.
1980
heart ablation of arrhythmogenic structures with predominantly used cryogenic t e c h n i q ~ e . ’The ~~ third is transvenous catheter ablation. Our experimental and technical investigation was directed toward the creation of a simple and least harmful technique of closed heart cryoablation. In cases where epicardial cryoablation had not been accessible, we used the new technique of intracardiac closed heart cryoablation developed in our clinic. The technique itself, in contrast to aortic cross clamping with cold cardioplegia, does not alter electrophysiological features of arrhythmogenic foci and accessory pathways, hence making intraoperative mapping and ablation efficacy control more natural. It also should be considered that frequent paroxysmal and incessant types of tachycardia as well as high dose long-term antiarrhythmic drug therapy often result in myocardial dystrophy and/or dilated cardiomyopathy-which are undesirable conditions for the use of CPB. Unlike the patients with other cardiac pathologies (such as congenital and valvular heart disease, coronary artery disease] where the open heart surgery may dramatically improve cardiac
‘December 1990, Part I1
PACE, Vol. 13
SURGERY OF TACHYARRHYTHMIA: INTRACARDIAC CLOSED HEART CRYOABLATION
hemodynamic or myocardial perfusion even during the operation, the patients with tachyarrhythmia have often been exposed only to the additional surgical trauma due to the use of a heartlung machine. Almost 20 years have elapsed since our first surgical intervention on closed heart without the use of CPB when we successfully performed Hisbundle electrocoagulation in a patient with drugrefractory tachysystolic atrial fibrillation that resulted in complete AV block. Since then the surgical technique of this procedure has been refined and now it appears as follows: the purse-string suture is placed on the central part of the right atrium for insertion of the surgeon's right index finger. The probe electrode and/or cryoinstrument is introduced through the second similar suture placed on the right auricle (Fig. 1).The tip of the cryoinstrument is precisely localized even under
digital control based on identification of internal anatomical landmarks such as tricuspid fibrous ring, orifice of inferior caval vein, coronary sinus ostium, and other anatomical structures. The AV node-His bundle as the target of ablation can be localized even without recording of His-bundle potential; having acquired experience one can do this either with soft pressing or by cryomapping (cryotest) since the temporary mechanical or thermal effect on AV node-His bundle immediately results in transient second- to third-degree AV block. Since 1977, we have used the cryoablation technique with liquid nitrogen. The effect of cryoablation is restricted to the local area so it does not cause an aneurysm and bring damage to the surrounding tissue. In the area of cryonecrosis, a firm scar develops, which is not arrhythmogenic. We have constructed special cryoinstruments
Figure 1. The scheme of intra-atrial closed heart procedure via right-sided thoracotomy.
PACE, Vol. 1 3
'December 1990, Part I1
1981
BREDIKIS, ET AL.
of two types; the first is designed for cryoablation in the septal region while the second with a slightly bent tip, is suitable for insertion into the coronary sinus. According to our experimental and clinical data, the main parameters for epicardial and endocardial cryoablation such as temperature and exposition time are almost similar and equal to - 60-70°C and 120-180 seconds, respectively. When the cryoactive part of the cryoinstrument is firmly fixed to the endocardium the circulating warm blood then washes around only the isolated surface of cryoinstrument. If compared with cardioplegic cold myocardium the focus of closed heart cryonecrosis is surrounded by a smaller transitional zone with reversible changes. During the atrial endocardia1 cryoprocedure the ice appears in 40-50 seconds on the epicardial surface. The depth of penetration of cryoeffect into the ventricular wall after 2 minutes of freezing is up to 11mm. No significant changes are found in either cardiac valves or the coronary sinus wall when those have been involved in a cryoprocedure. Undesirable effects of cryoablation have been observed in larger arteries; according to our
experimental data the cryogenic effect on arteries may result in intimal hyperplasia with partial lumen narrowing and thrombosis. At the present time, we prefer to perform all antiarrhythmic operations (except for some cases of ventricular tachycardia) on the closed heart without the use of CPB. Our experience in arrhythmia surgery covers over 1,200 operations. three hundred and twenty nine of those operations have been performed with the intracardiac cryoablation technique (Table I). Now we rarely use cryoablation technique for creation of AV block. Intra-atrial cryoablation in AV node-His bundle area allows modification of AV conduction. Our modification of surgical technique for the elimination of AV nodal tachycardia implies the performance of intracardiac closed heart paranodal cryoablation instead of dissecting AV node anteriorly and posteriorly from surrounding perinodal tissue as was suggested by Ross and others5 (Fig. 2). The distance of the tip of the cryoinstrument from the AV node is assumed to be optimum when during the cryoprocedure the second- to third-degree AV block begins to develop over 60-90 seconds of exposition.
Table I. lntracardiac Cryoablation of Tachyarrhythmia (Closed Heart Technique)
Type of Arrhythmia
Atrial fibrillation or/and flutter
Ectopic atrial tachycardia AV junctional tachycardia Ventricular arrhythmia TOTAL
Type of Surgery 1. Cryoablation of AV node, His bundle & implantation of pulse generator Total or partial cryoisolation of right or left atrium, cryof ragmentation Cryoablation of septal ectopic foci Paranodal cryoablation
Number of Operations
Arrhythmia Free Pts
Improved
No Changes, Recurrences
Mortality
72
66
4
1
1
33
12
-
0
26
25
0
1
0
53
51
1
1
0
23
16
4
3
1
207
160
6
2
5
14
-+ 16*
+
16*
' sinus rhythm with antiarrhythmic drugs
1982
December 1990,Part I1
PACE, Vol. 13
SURGERY OF TACHYARRHYTHMIA: INTRACARDIAC CLOSED HEART CRYOABLATION
R
Figure 2. The scheme of intra-atrial closed heart paranodal cryoablation anteriorly and posteriorly to the AV node.
This technique is also successfully used in cases of enhanced AV conduction which may accompany other tachycardias or be due to the manifestation of accessory atrionodal or atriofascicular pathways (LGL syndrome). Operating on patients with atrial flutter and/or fibrillation, we performed paranodal cryoablation in order to decrease AV conduction to 90-110 imp/min. Ectopic atrial tachycardia with ectopic focus in atrial septal position should always be differentiated from incessant AV reciprocating tachycardia utilizing “slow” septal Kent bundles for retrograde conduction. Such foci of ectopic atrial tachycardia are often found in the vicinity of coronary sinus ostium. In many cases it is possible to localize the ectopic focus by slightly pressing the border of ostium with the index finger inserted into the right atrium, which is followed by cessation of ectopic tachycardia; cryoprocedure is applied to this area. The same area is exposed to the cryoprocedure in patients with macro-reentrant atrial flutter provided the area of slow conduction is localized in the low posterior and/or low septal right atrium; for this purpose we perform intra-atrial cryoablation from the coronary sinus ostium to tricuspid fibrous ring and orifice of inferior caval vein. We also introduced the intracardiac technique for cryoablation of septal posterior accessory pathways. We suggested performing cryoab-
PACE, Vol. 13
lation of paraseptal left posterior Kent bundle via coronary sinus by inserting the tip of cryodestructor into the coronary sinus ostium. This procedure may also be performed only under the external finger control in the region of crux without finger insertion into the right atrium. In the case of right anterior septal Kent bundle, first we made an attempt to perform cryoablation externally and in most of cases we succeeded. When using intracardiac technique under aforementioned inside digital control we localized cryoinstruments anteriorly to the AV node and performed two or three cryoprocedures close to the fibrous ring. As in the case of posterior septal accessory pathways, the AV conduction is continuously controlled and the procedure is stopped as soon as the second- to third-degree AV block is developed. Since 1988, intracardiac cryoablation technique has also been used as a part of the complex procedure of right atrium isolation in patients with paroxysmal atrial fibrillation. We have also demonstrated the feasibility of intraventricular cryoablation. Our first two patients with recurrent and incessant ventricular tachycardia could not be operated on with using CPB because of their poor general condition. The first patient was a 68-year-old man with two prior myocardial infarctions and left ventricular anterior wall aneurysm. He suffered from severe congestive heart failure. Intraoperative epicardial mapping revealed two different foci of tachycardia in the aneurysm border zone. The cryoinstrument was introduced via the left ventricular apex with its tip being precisely localized in the left ventricle; then the scar-encircling transmural cryoisolation was performed. Tachycardia was not inducible after the surgery and the patient has still remained tachycardia-free after a follow-up of 2 years. The second patient was a 14-month-old child with severe heart failure due to incessant ventricular tachycardia. Intraoperative epicardial mapping revealed the arrhythmogenic zone in the paraseptal area of left ventricular inferior wall. Endocardial cryoablation was performed successfully. In this case the small incision in the left ventricle would not be enough for endocardia1 procedure and could significantly reduce cardiac output. These observations make it feasible to per-
December 1990, Part I1
1983
BREDIKIS, ET AL.
form intraventricular cryoablation especially in patients with idiopathic ventricular tachycardia and ventricular premature beats without local visible anatomical substrates. The cryoinstrument is usually introduced via the apex of either left or right ventricle. The arrhythmogenic site is determined by means of either simple or computer mapping. Cryomapping and pacemapping are also useful. Successful outcome (that is percentage of arrhythmia-free patients) of intracardiac cryoablation procedure in certain types of tachyarrhythmia reaches 82°/0-1000h with no lethal cases in the last series of supraventricular tachyarrhythmias. Percentage of recurrences averages 3%-12%. As our experience has shown those patients may suc-
cessfully be reoperated in the same way without the use of CPB. Our results of intracardiac close heart cryoablation are similar to those of most advanced centers where these operations have been performed with the use of CPB. It should be emphasized that the intracardiac cryoablation has got several advantages such as the possibility of continuous monitoring of cardiac electrical activity and control of ablation efficacy during the operation as well as the possibility of prevention of AV nodeHis bundle damage. Surgical intervention without the use of CPB is less traumatic with no need of donor blood transfusion and is associated with decreased number of complications and low mortality.
References 1. Bredikis J. Cryosurgical ablation of atrioventricular
junction without extracorporeal circulation. J Thorac Cadiovasc Surg 1985; 90:61-67. 2. Bredikis J, Bukauskas F, Zebrauskas R, et al. Cryosurgical ablation of right parietal and septa1 accessory atrioventricular connections without the use of extracorporeal circulation. A new surgical techniqe. J Thorac Cardiovasc Surg 1985; 90:206211.
3. Bredikis J. Surgery of supraventricular tachyar-
1984
rhythmias: The present and the future. Eur J Cardiothorac Surg 1988; 2:8-17. 4. Guiraudon GM, Klein GJ, Gulamhusein S, et al. Surgical repair of Wolff-Parkinson-White syndrome. A new closed-heart technique. Ann Thorac Surg 1984; 37:67-71. 5. Ross DL, Johnson DC, Deniss AR, et al. Curative surgery for atrioventricular junctional (“AV nodal”) reentrant tachycardia. J Am Coll Cardiol 1985; 6:1383-1392.
December 1990, Part I1
PACE, Vol. 13
BREDIKIS, J. J., ET AL.: Surgery of Tachyarrhythmia: Intracardiac Closed Heart Cryoablation. Closed heart surgery without the use of cardiopulmonary bypass (CPB) is one of the trends of surgical treatment of tachyarrhythmias. Having rich experience of epicardial cryoablation, the authors introduced the original technique of intracardiac cryoablation. They have demonstrated the feasibility of creation of complete AV block in patients with supraventricular tachycardias by AV node-His-bundle cryoablation, elimaintion of AV junctional (“nodal”) tachycardia by perinodal cryoablation, cryoablation of septa1 and paraseptal left posterior AV accessory pathways and ectopic foci in atrial septum, complete or partial cryoisolation or cryofragmentation of the atria in patients with atrial flutter and/or fibrillation, and cryoablation or arrhythmogenic zones in ventricles. Good results (arrhythmia-free patients) were obtained in 82%-100%. Cryoablation on the closed heart without the use of CPB has the following advantages: (a) the possibility of continuous monitoring of cardiac electrical activity during the operation; (b) ablation efficacy control; and (c) dimished trauma and little risk of surgical intervention. [PACE, Vol. 13, December, Part I1 1990) tachycardia, intracardiac cryoablation
Introduction Arrhythmia surgery is the most important trend of cardiovascular surgery that has been intensively developed for the last decade. This “surgical breakthrough” in arrhythmia treatment is particularly due to better understanding of underlying electrophysiological mechanisms and anatomical substrates of tachycardias, as well as to progress in clinical cardiac electrophysiology and computer-assisted intraoperative mapping. On the other hand, the implementation of new methods such as thermocoagulation, electrical fulguration, cryoablation, and laser or microwave techniques further facilitated surgical destruction of arrhythmogenic substrates. There are three main ways of antitachycardia surgery. The first one is the open heart surgery with the use of cardiopulmonary bypass (CPB). The second is the external (epicardial) closed
Address for reprints: Professor Jurgis J. Bredikis, M.D., Kaunas Arrhythmia Surgery Center, Z. Januskevicius 2.. 233000, Kaunas, Lithuania.
1980
heart ablation of arrhythmogenic structures with predominantly used cryogenic t e c h n i q ~ e . ’The ~~ third is transvenous catheter ablation. Our experimental and technical investigation was directed toward the creation of a simple and least harmful technique of closed heart cryoablation. In cases where epicardial cryoablation had not been accessible, we used the new technique of intracardiac closed heart cryoablation developed in our clinic. The technique itself, in contrast to aortic cross clamping with cold cardioplegia, does not alter electrophysiological features of arrhythmogenic foci and accessory pathways, hence making intraoperative mapping and ablation efficacy control more natural. It also should be considered that frequent paroxysmal and incessant types of tachycardia as well as high dose long-term antiarrhythmic drug therapy often result in myocardial dystrophy and/or dilated cardiomyopathy-which are undesirable conditions for the use of CPB. Unlike the patients with other cardiac pathologies (such as congenital and valvular heart disease, coronary artery disease] where the open heart surgery may dramatically improve cardiac
‘December 1990, Part I1
PACE, Vol. 13
SURGERY OF TACHYARRHYTHMIA: INTRACARDIAC CLOSED HEART CRYOABLATION
hemodynamic or myocardial perfusion even during the operation, the patients with tachyarrhythmia have often been exposed only to the additional surgical trauma due to the use of a heartlung machine. Almost 20 years have elapsed since our first surgical intervention on closed heart without the use of CPB when we successfully performed Hisbundle electrocoagulation in a patient with drugrefractory tachysystolic atrial fibrillation that resulted in complete AV block. Since then the surgical technique of this procedure has been refined and now it appears as follows: the purse-string suture is placed on the central part of the right atrium for insertion of the surgeon's right index finger. The probe electrode and/or cryoinstrument is introduced through the second similar suture placed on the right auricle (Fig. 1).The tip of the cryoinstrument is precisely localized even under
digital control based on identification of internal anatomical landmarks such as tricuspid fibrous ring, orifice of inferior caval vein, coronary sinus ostium, and other anatomical structures. The AV node-His bundle as the target of ablation can be localized even without recording of His-bundle potential; having acquired experience one can do this either with soft pressing or by cryomapping (cryotest) since the temporary mechanical or thermal effect on AV node-His bundle immediately results in transient second- to third-degree AV block. Since 1977, we have used the cryoablation technique with liquid nitrogen. The effect of cryoablation is restricted to the local area so it does not cause an aneurysm and bring damage to the surrounding tissue. In the area of cryonecrosis, a firm scar develops, which is not arrhythmogenic. We have constructed special cryoinstruments
Figure 1. The scheme of intra-atrial closed heart procedure via right-sided thoracotomy.
PACE, Vol. 1 3
'December 1990, Part I1
1981
BREDIKIS, ET AL.
of two types; the first is designed for cryoablation in the septal region while the second with a slightly bent tip, is suitable for insertion into the coronary sinus. According to our experimental and clinical data, the main parameters for epicardial and endocardial cryoablation such as temperature and exposition time are almost similar and equal to - 60-70°C and 120-180 seconds, respectively. When the cryoactive part of the cryoinstrument is firmly fixed to the endocardium the circulating warm blood then washes around only the isolated surface of cryoinstrument. If compared with cardioplegic cold myocardium the focus of closed heart cryonecrosis is surrounded by a smaller transitional zone with reversible changes. During the atrial endocardia1 cryoprocedure the ice appears in 40-50 seconds on the epicardial surface. The depth of penetration of cryoeffect into the ventricular wall after 2 minutes of freezing is up to 11mm. No significant changes are found in either cardiac valves or the coronary sinus wall when those have been involved in a cryoprocedure. Undesirable effects of cryoablation have been observed in larger arteries; according to our
experimental data the cryogenic effect on arteries may result in intimal hyperplasia with partial lumen narrowing and thrombosis. At the present time, we prefer to perform all antiarrhythmic operations (except for some cases of ventricular tachycardia) on the closed heart without the use of CPB. Our experience in arrhythmia surgery covers over 1,200 operations. three hundred and twenty nine of those operations have been performed with the intracardiac cryoablation technique (Table I). Now we rarely use cryoablation technique for creation of AV block. Intra-atrial cryoablation in AV node-His bundle area allows modification of AV conduction. Our modification of surgical technique for the elimination of AV nodal tachycardia implies the performance of intracardiac closed heart paranodal cryoablation instead of dissecting AV node anteriorly and posteriorly from surrounding perinodal tissue as was suggested by Ross and others5 (Fig. 2). The distance of the tip of the cryoinstrument from the AV node is assumed to be optimum when during the cryoprocedure the second- to third-degree AV block begins to develop over 60-90 seconds of exposition.
Table I. lntracardiac Cryoablation of Tachyarrhythmia (Closed Heart Technique)
Type of Arrhythmia
Atrial fibrillation or/and flutter
Ectopic atrial tachycardia AV junctional tachycardia Ventricular arrhythmia TOTAL
Type of Surgery 1. Cryoablation of AV node, His bundle & implantation of pulse generator Total or partial cryoisolation of right or left atrium, cryof ragmentation Cryoablation of septal ectopic foci Paranodal cryoablation
Number of Operations
Arrhythmia Free Pts
Improved
No Changes, Recurrences
Mortality
72
66
4
1
1
33
12
-
0
26
25
0
1
0
53
51
1
1
0
23
16
4
3
1
207
160
6
2
5
14
-+ 16*
+
16*
' sinus rhythm with antiarrhythmic drugs
1982
December 1990,Part I1
PACE, Vol. 13
SURGERY OF TACHYARRHYTHMIA: INTRACARDIAC CLOSED HEART CRYOABLATION
R
Figure 2. The scheme of intra-atrial closed heart paranodal cryoablation anteriorly and posteriorly to the AV node.
This technique is also successfully used in cases of enhanced AV conduction which may accompany other tachycardias or be due to the manifestation of accessory atrionodal or atriofascicular pathways (LGL syndrome). Operating on patients with atrial flutter and/or fibrillation, we performed paranodal cryoablation in order to decrease AV conduction to 90-110 imp/min. Ectopic atrial tachycardia with ectopic focus in atrial septal position should always be differentiated from incessant AV reciprocating tachycardia utilizing “slow” septal Kent bundles for retrograde conduction. Such foci of ectopic atrial tachycardia are often found in the vicinity of coronary sinus ostium. In many cases it is possible to localize the ectopic focus by slightly pressing the border of ostium with the index finger inserted into the right atrium, which is followed by cessation of ectopic tachycardia; cryoprocedure is applied to this area. The same area is exposed to the cryoprocedure in patients with macro-reentrant atrial flutter provided the area of slow conduction is localized in the low posterior and/or low septal right atrium; for this purpose we perform intra-atrial cryoablation from the coronary sinus ostium to tricuspid fibrous ring and orifice of inferior caval vein. We also introduced the intracardiac technique for cryoablation of septal posterior accessory pathways. We suggested performing cryoab-
PACE, Vol. 13
lation of paraseptal left posterior Kent bundle via coronary sinus by inserting the tip of cryodestructor into the coronary sinus ostium. This procedure may also be performed only under the external finger control in the region of crux without finger insertion into the right atrium. In the case of right anterior septal Kent bundle, first we made an attempt to perform cryoablation externally and in most of cases we succeeded. When using intracardiac technique under aforementioned inside digital control we localized cryoinstruments anteriorly to the AV node and performed two or three cryoprocedures close to the fibrous ring. As in the case of posterior septal accessory pathways, the AV conduction is continuously controlled and the procedure is stopped as soon as the second- to third-degree AV block is developed. Since 1988, intracardiac cryoablation technique has also been used as a part of the complex procedure of right atrium isolation in patients with paroxysmal atrial fibrillation. We have also demonstrated the feasibility of intraventricular cryoablation. Our first two patients with recurrent and incessant ventricular tachycardia could not be operated on with using CPB because of their poor general condition. The first patient was a 68-year-old man with two prior myocardial infarctions and left ventricular anterior wall aneurysm. He suffered from severe congestive heart failure. Intraoperative epicardial mapping revealed two different foci of tachycardia in the aneurysm border zone. The cryoinstrument was introduced via the left ventricular apex with its tip being precisely localized in the left ventricle; then the scar-encircling transmural cryoisolation was performed. Tachycardia was not inducible after the surgery and the patient has still remained tachycardia-free after a follow-up of 2 years. The second patient was a 14-month-old child with severe heart failure due to incessant ventricular tachycardia. Intraoperative epicardial mapping revealed the arrhythmogenic zone in the paraseptal area of left ventricular inferior wall. Endocardial cryoablation was performed successfully. In this case the small incision in the left ventricle would not be enough for endocardia1 procedure and could significantly reduce cardiac output. These observations make it feasible to per-
December 1990, Part I1
1983
BREDIKIS, ET AL.
form intraventricular cryoablation especially in patients with idiopathic ventricular tachycardia and ventricular premature beats without local visible anatomical substrates. The cryoinstrument is usually introduced via the apex of either left or right ventricle. The arrhythmogenic site is determined by means of either simple or computer mapping. Cryomapping and pacemapping are also useful. Successful outcome (that is percentage of arrhythmia-free patients) of intracardiac cryoablation procedure in certain types of tachyarrhythmia reaches 82°/0-1000h with no lethal cases in the last series of supraventricular tachyarrhythmias. Percentage of recurrences averages 3%-12%. As our experience has shown those patients may suc-
cessfully be reoperated in the same way without the use of CPB. Our results of intracardiac close heart cryoablation are similar to those of most advanced centers where these operations have been performed with the use of CPB. It should be emphasized that the intracardiac cryoablation has got several advantages such as the possibility of continuous monitoring of cardiac electrical activity and control of ablation efficacy during the operation as well as the possibility of prevention of AV nodeHis bundle damage. Surgical intervention without the use of CPB is less traumatic with no need of donor blood transfusion and is associated with decreased number of complications and low mortality.
References 1. Bredikis J. Cryosurgical ablation of atrioventricular
junction without extracorporeal circulation. J Thorac Cadiovasc Surg 1985; 90:61-67. 2. Bredikis J, Bukauskas F, Zebrauskas R, et al. Cryosurgical ablation of right parietal and septa1 accessory atrioventricular connections without the use of extracorporeal circulation. A new surgical techniqe. J Thorac Cardiovasc Surg 1985; 90:206211.
3. Bredikis J. Surgery of supraventricular tachyar-
1984
rhythmias: The present and the future. Eur J Cardiothorac Surg 1988; 2:8-17. 4. Guiraudon GM, Klein GJ, Gulamhusein S, et al. Surgical repair of Wolff-Parkinson-White syndrome. A new closed-heart technique. Ann Thorac Surg 1984; 37:67-71. 5. Ross DL, Johnson DC, Deniss AR, et al. Curative surgery for atrioventricular junctional (“AV nodal”) reentrant tachycardia. J Am Coll Cardiol 1985; 6:1383-1392.
December 1990, Part I1
PACE, Vol. 13
