Coronary Air Embolism Complicating Transseptal Radiofrequency Ablation of Left Free-Wall Accessory Patbways MICHAEL D. LESH, DWAIN L. COGGINS, and THOMAS A. PORTS From the Department of Medicine and the Cardiovascular Research Institute, University of California, San Francisco, California LESH, M.D., ET AL.: Coronary Air Embolism Complicating Transseptal Radiofrequency Ablation of Lefl
Free-Wall Accessory Pathways. Hadiofrequency catheter ablation is an important new technique for curing patients with accessory pathway-mediated tachycardia. Ablation of left free-wall accessory pathways may be accomplished either by a retrograde, transarteriai approach or via a transseptal approach using a long vascuiar sheath. We describe air embolization into the coronary artery as a complication of the transseptal approach, which was temporally associated with catheter exchange. While there were no permanent adverse sequelae, this report emphasizes the need for scrupulous attention to the possible insinuation o/air during procedures involving Jong vascular sheaths across the atrial septum. To prevent air embolism, we recommend slow removal 0/ the ablation catheter along with continuous flushing with heparinized saline during exchanges. (PACE, Vol. 15, August 1992} radio/requency catheter ablation, air epiboJism, transseptaJ catheterization
Introduction
Case Report
Percutaneous radiofrequency catheter ablation of accessory pathways is achieving widespread application in treating patients with paroxysmal supraventricular tachycardia.^^ While the procedure is generally well tolerated, it is not without potential complications. Access to the mitral annulus in patients with left free-wall accessory pathways can be obtained either via a retrograde transarteriai, transaortic approach or via a transseptal puncture.^ The transseptal approach reduces the risk of mechanical damage to the aortic valve^ and coronary arteries. However, as we report here, placing a long vascular sheath across the septum into the left atrium engenders the risk of air embolism, especially when there are multiple catheter exchanges in and out of such a sheath.
A 47-year-old man had a history of palpitations and presyncope for over 20 years and was recently diagnosed as having the Wolff-ParkinsonWhite syndrome and paroxysmal supraventricular tachycardia. Empiric antiarrhythmic drug therapy had proven ineffective and he was offered radiofrequency catheter ablation of the accessory pathway. His 12-lead ECG (Fig. la) showed a pattern of ventricular preexcitation consistent with a left free-wall accessory pathway. At electrophysiological study, initial mapping in the coronary sinus confirmed the presence of a left anterolateral accessory pathway. A transseptal approach to ablation along the mitral annulus was used. Using standard technique,^'^ the intraatrial septum was punctured and an 8 French sheath with infusion side port and backbleed gasket seal [USCI Angiographic Systems, Division of CR Bard, Inc., Tewksbury, MA, USA) was delivered across the septum into the left atrium without difficulty. A 7 French tip-deflecting catheter with large distal electrode [Mansfield Scientific, Boston, MA, USA) was passed through the transseptal sheath and the
Address for reprints: Michael D. Lesh, M.D., Room 312 Moffitt Hospital, Box 0214, University of California, San Francisco, CA 94143. Fax: (415) 476-6260. Received lanuary 30, 1992; revision March 23, 1992: accepted March 24. 1992.
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Figure 1. (a) Twelve-lead ECG in baseline state showing short PR interval and delta wave pattern consistent with a left free-wall accessory pathway, (b) Twelve-lead ECG obtained shortly after the removal of an ablation catheter from the transseptal sheath. Patient is compJainiiig of severe chest discomfort. Note marked inferior ST segment elevation.
anterolateral mitral annulus mapped until an accessory pathway potential was recorded during sinus rhythm. Three applications of radiofrequency energy were delivered but each resulted in only transient loss of preexcitation. The 7 French ablation catheter was removed and replaced with a catheter possessing an 8 French distal electrode (EP Technology, Mountain View, CA, USA), Application of radiofrequency energy through this catheter resulted in an impedance rise, necessitating its removal to clean coagulum from the tip. After removal of the 8 French catheter, a second 7 French catheter was placed into the left atrium. Approximately 2 minutes following this last catheter exchange, the patient complained of severe chest pain. An ECG at that time (Fig, lh) showed marked ST segment elevation in the infe-
1106
rior leads. Interestingly, there is an increase in the degree of ventricular preexcitation, possibly related to AV nodal ischemia and consequent prolonged conduction. A right coronary angiogram obtained within 3 minutes of tbe onset of chest pain revealed several bubbles of air obstructing flow to the distal vessel (Fig. 2). Nitroglycerin and oxygen were administered. Several forceful injections of contrast medium were made into the coronary artery resulting in fragmentation of the large occlusive air bubble witb consequent improved coronary blood flow. Over the next several minutes, tbe pain and ST segment elevation resolved and repeat angiography of the rigbt and left coronary arteries showed no abnormalities. There was no clinical evidence of air embolization to any other organ.
August 1992
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AIR EMBOLISM COMPLICATING ABLATION
Figure 2. Right anterior oblique view of right coronary angiogram obtained during chest pain. Note air bubbles (arrows) restricting flow in the artery. CS — coronary sinus catheter; RA ^ high right atriaJ catheter; TS = transseptal sheath.
The ablation procedure was continued, ultimately yielding permanent elimination of accessory pathway conduction. Follow-up echocardiogram showed normal wall motion, creatinine phosphokinase levels were not elevated, and no Q waves developed on the electrocardiogram.
Discussion This case clearly documents embolization of air into the right coronary in association with transseptal catheter ablation of a left free-wall accessory pathway. Fortunately, myocardial infarction did not occur, though air embolization must be considered a potentially life-threatening complication of the procedure. In reviewing the records of 30 transseptal procedures performed for accessory pathway ablation for adults and children** at our institution, we noted an additional case in which coronary air embolization may have occurred. As in the case above, the patient had chest pain and transient ST segment changes shortly after catheter exchange through the transseptal sheath. Though attributed at the time to coronary spasm, it seems likely in retrospect to have been related to a coronary air embolism,
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since in none of 85 cases performed via the retrograde approach has coronary spasm been suspected. Coronary air embolism is a recognized complication of coronary angiography,^ angioplasty,^° and balloon mitral valvuloplasty.^^ It may mimic coronary spasm.^ Management, once the complication is recognized, is generally supportive.^" Coronary angiography may break up large air bubbles and improve coronary blood flow. It may also be possible to actively withdraw air using a small infusion catheter inserted into the coronary. In our cases, the most likely source of air was through the transseptal sheath and occurred contemporaneously with catheter exchange. When one considers that the internal volume of an 8 French transseptal sheath is approximately 15 mL, and that the sheath is entering a low pressure chamber, it is not surprising that air embolism can be associated with transseptal procedures. It had been our practice to leave the infusion side port of the transseptal sheath closed during mapping and ablation, and then to draw back from the side port and flush with heparinized saline after removal of a catheter from the sheath. We hypothesize that despite this technique, air was drawn into the sheath and delivered into the left atrium where it subsequently embolized to the right coronary. Rapid removal of the ablation catheter from the sheath, in our case to remove coagulum, can create a vacuum, especially when an 8 French catheter is removed from a sheath of the same size. This vacuum will tend to draw air in from the backbleed seal, the gasket of which may have diminished structural integrity after multiple exchanges through it with catheters of varying diameter. The entrained air could then insinuate into the left atrium before the operator was able to withdraw and flush through the sheath side port.
Clinical Implications With the widespread application of catheter ablation, electrophysiology has gone from a diagnostic exercise to an invasive, therapeutic modality and concomitantly there has been rapid introduction [or adaptation) of new techniques and devices. While the overall rate of serious complications with radiofrequency catheter ablation is low, careful attention to technique must be
August 1992
1107
LESH, ET AL,
used in order to minimize the risk. In particular, a scrupulous effort must be made to prevent the possible introduction of a large volume of air into sheaths placed into the low pressure left atrium when the transseptal approach is used for ablation of left free-wall pathways. Therefore, to prevent air embolization during catheter exchange through
a transseptal sheath, we now recommend tbe following: (1) maintain a continuous flow of heparinized saline delivered at moderate pressure through the side port during removal and introduction of the ablation catheter; and (2) slow removal of the ablation catheter to avoid build up of negative pressure.
References 1. Calkins H, Sousa ), El-Atassi R, et al. Diagnosis and cure of theWolff-Parkinson-White syndrome and paroxysmal supraventricular tachycardia during a single electrophysiology test, N Engl J Med 1991; 324:1612-1616, 2. Jackman WM, Wang X, Friday KJ, et al. Catheter ablation of accessory atrioventricular pathways (Wolff-Parkinson-White syndrome) by radiofrequency current, N Engl J Med 1991: 324: 1605-1611, 3. Lesh MD, Van Hare GF, Schamp DJ, et al. Curative percutaneous catheter ablation using radiofrequency energy for accessory pathways in all locations: Results in 100 consecutive patients. J Am Coll Cardiol 1992; in press, 4. Tracy C, Swartz J, Fletcher R. et al. Atrial endocardial ablation of accessory pathways. J Am Coll Cardiol 1991; 17:368A, 5. Seifert MJ, Morady F, Calkins HC, et al. Aortic leaflet perforation during radiofrequency ablation, PACE 1992; 14:1582-1585. 6. Brockenbrough EC, Braunwald E. A new technique
1108
7. 8.
9.
10,
11,
August 1992
for left ventricular angiocardiography and transseptal left heart catheterization. Am J Cardiol 1960: 6:1062, Neches WH, Mullins CE, Williams RL, et al. Percutaneous sheath cardiac catheterization. Am J Cardiol 1972; 30:378-384, Van Hare CF, Lesh MD, Scheinman MM, et al. Percutaneous radiofrequency catheter ablation for supraventricular arrhythmias in children. J Am Coll Cardiol 1991; 17:1613-1620, Amar R, Halon DA, Lewis BS, Myocardial damage following coronary air embolism during coronary angiography. Cathet Cardiovasc Diagn 1987; 13:39-41. Kahn JK. Hartzler GO. The spectrum of symptomatic coronary air embolism during balloon angioplasty: Causes, consequences, and management. Am Heart J 1990; 119:1374-1377. Bassand JP, Schiele F, Bernard Y, et al. The doubleballoon and Inoue techniques in percutaneous mitral valvuloplasty: Comparative results in a series of 232 cases, J Am Coll Cardiol 1991; 18:982-989.
PACE, Vol. 15
Free-Wall Accessory Pathways. Hadiofrequency catheter ablation is an important new technique for curing patients with accessory pathway-mediated tachycardia. Ablation of left free-wall accessory pathways may be accomplished either by a retrograde, transarteriai approach or via a transseptal approach using a long vascuiar sheath. We describe air embolization into the coronary artery as a complication of the transseptal approach, which was temporally associated with catheter exchange. While there were no permanent adverse sequelae, this report emphasizes the need for scrupulous attention to the possible insinuation o/air during procedures involving Jong vascular sheaths across the atrial septum. To prevent air embolism, we recommend slow removal 0/ the ablation catheter along with continuous flushing with heparinized saline during exchanges. (PACE, Vol. 15, August 1992} radio/requency catheter ablation, air epiboJism, transseptaJ catheterization
Introduction
Case Report
Percutaneous radiofrequency catheter ablation of accessory pathways is achieving widespread application in treating patients with paroxysmal supraventricular tachycardia.^^ While the procedure is generally well tolerated, it is not without potential complications. Access to the mitral annulus in patients with left free-wall accessory pathways can be obtained either via a retrograde transarteriai, transaortic approach or via a transseptal puncture.^ The transseptal approach reduces the risk of mechanical damage to the aortic valve^ and coronary arteries. However, as we report here, placing a long vascular sheath across the septum into the left atrium engenders the risk of air embolism, especially when there are multiple catheter exchanges in and out of such a sheath.
A 47-year-old man had a history of palpitations and presyncope for over 20 years and was recently diagnosed as having the Wolff-ParkinsonWhite syndrome and paroxysmal supraventricular tachycardia. Empiric antiarrhythmic drug therapy had proven ineffective and he was offered radiofrequency catheter ablation of the accessory pathway. His 12-lead ECG (Fig. la) showed a pattern of ventricular preexcitation consistent with a left free-wall accessory pathway. At electrophysiological study, initial mapping in the coronary sinus confirmed the presence of a left anterolateral accessory pathway. A transseptal approach to ablation along the mitral annulus was used. Using standard technique,^'^ the intraatrial septum was punctured and an 8 French sheath with infusion side port and backbleed gasket seal [USCI Angiographic Systems, Division of CR Bard, Inc., Tewksbury, MA, USA) was delivered across the septum into the left atrium without difficulty. A 7 French tip-deflecting catheter with large distal electrode [Mansfield Scientific, Boston, MA, USA) was passed through the transseptal sheath and the
Address for reprints: Michael D. Lesh, M.D., Room 312 Moffitt Hospital, Box 0214, University of California, San Francisco, CA 94143. Fax: (415) 476-6260. Received lanuary 30, 1992; revision March 23, 1992: accepted March 24. 1992.
PACE, Vol. 15
August 1992
1105
LESH, ET AL.
Figure 1. (a) Twelve-lead ECG in baseline state showing short PR interval and delta wave pattern consistent with a left free-wall accessory pathway, (b) Twelve-lead ECG obtained shortly after the removal of an ablation catheter from the transseptal sheath. Patient is compJainiiig of severe chest discomfort. Note marked inferior ST segment elevation.
anterolateral mitral annulus mapped until an accessory pathway potential was recorded during sinus rhythm. Three applications of radiofrequency energy were delivered but each resulted in only transient loss of preexcitation. The 7 French ablation catheter was removed and replaced with a catheter possessing an 8 French distal electrode (EP Technology, Mountain View, CA, USA), Application of radiofrequency energy through this catheter resulted in an impedance rise, necessitating its removal to clean coagulum from the tip. After removal of the 8 French catheter, a second 7 French catheter was placed into the left atrium. Approximately 2 minutes following this last catheter exchange, the patient complained of severe chest pain. An ECG at that time (Fig, lh) showed marked ST segment elevation in the infe-
1106
rior leads. Interestingly, there is an increase in the degree of ventricular preexcitation, possibly related to AV nodal ischemia and consequent prolonged conduction. A right coronary angiogram obtained within 3 minutes of tbe onset of chest pain revealed several bubbles of air obstructing flow to the distal vessel (Fig. 2). Nitroglycerin and oxygen were administered. Several forceful injections of contrast medium were made into the coronary artery resulting in fragmentation of the large occlusive air bubble witb consequent improved coronary blood flow. Over the next several minutes, tbe pain and ST segment elevation resolved and repeat angiography of the rigbt and left coronary arteries showed no abnormalities. There was no clinical evidence of air embolization to any other organ.
August 1992
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AIR EMBOLISM COMPLICATING ABLATION
Figure 2. Right anterior oblique view of right coronary angiogram obtained during chest pain. Note air bubbles (arrows) restricting flow in the artery. CS — coronary sinus catheter; RA ^ high right atriaJ catheter; TS = transseptal sheath.
The ablation procedure was continued, ultimately yielding permanent elimination of accessory pathway conduction. Follow-up echocardiogram showed normal wall motion, creatinine phosphokinase levels were not elevated, and no Q waves developed on the electrocardiogram.
Discussion This case clearly documents embolization of air into the right coronary in association with transseptal catheter ablation of a left free-wall accessory pathway. Fortunately, myocardial infarction did not occur, though air embolization must be considered a potentially life-threatening complication of the procedure. In reviewing the records of 30 transseptal procedures performed for accessory pathway ablation for adults and children** at our institution, we noted an additional case in which coronary air embolization may have occurred. As in the case above, the patient had chest pain and transient ST segment changes shortly after catheter exchange through the transseptal sheath. Though attributed at the time to coronary spasm, it seems likely in retrospect to have been related to a coronary air embolism,
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since in none of 85 cases performed via the retrograde approach has coronary spasm been suspected. Coronary air embolism is a recognized complication of coronary angiography,^ angioplasty,^° and balloon mitral valvuloplasty.^^ It may mimic coronary spasm.^ Management, once the complication is recognized, is generally supportive.^" Coronary angiography may break up large air bubbles and improve coronary blood flow. It may also be possible to actively withdraw air using a small infusion catheter inserted into the coronary. In our cases, the most likely source of air was through the transseptal sheath and occurred contemporaneously with catheter exchange. When one considers that the internal volume of an 8 French transseptal sheath is approximately 15 mL, and that the sheath is entering a low pressure chamber, it is not surprising that air embolism can be associated with transseptal procedures. It had been our practice to leave the infusion side port of the transseptal sheath closed during mapping and ablation, and then to draw back from the side port and flush with heparinized saline after removal of a catheter from the sheath. We hypothesize that despite this technique, air was drawn into the sheath and delivered into the left atrium where it subsequently embolized to the right coronary. Rapid removal of the ablation catheter from the sheath, in our case to remove coagulum, can create a vacuum, especially when an 8 French catheter is removed from a sheath of the same size. This vacuum will tend to draw air in from the backbleed seal, the gasket of which may have diminished structural integrity after multiple exchanges through it with catheters of varying diameter. The entrained air could then insinuate into the left atrium before the operator was able to withdraw and flush through the sheath side port.
Clinical Implications With the widespread application of catheter ablation, electrophysiology has gone from a diagnostic exercise to an invasive, therapeutic modality and concomitantly there has been rapid introduction [or adaptation) of new techniques and devices. While the overall rate of serious complications with radiofrequency catheter ablation is low, careful attention to technique must be
August 1992
1107
LESH, ET AL,
used in order to minimize the risk. In particular, a scrupulous effort must be made to prevent the possible introduction of a large volume of air into sheaths placed into the low pressure left atrium when the transseptal approach is used for ablation of left free-wall pathways. Therefore, to prevent air embolization during catheter exchange through
a transseptal sheath, we now recommend tbe following: (1) maintain a continuous flow of heparinized saline delivered at moderate pressure through the side port during removal and introduction of the ablation catheter; and (2) slow removal of the ablation catheter to avoid build up of negative pressure.
References 1. Calkins H, Sousa ), El-Atassi R, et al. Diagnosis and cure of theWolff-Parkinson-White syndrome and paroxysmal supraventricular tachycardia during a single electrophysiology test, N Engl J Med 1991; 324:1612-1616, 2. Jackman WM, Wang X, Friday KJ, et al. Catheter ablation of accessory atrioventricular pathways (Wolff-Parkinson-White syndrome) by radiofrequency current, N Engl J Med 1991: 324: 1605-1611, 3. Lesh MD, Van Hare GF, Schamp DJ, et al. Curative percutaneous catheter ablation using radiofrequency energy for accessory pathways in all locations: Results in 100 consecutive patients. J Am Coll Cardiol 1992; in press, 4. Tracy C, Swartz J, Fletcher R. et al. Atrial endocardial ablation of accessory pathways. J Am Coll Cardiol 1991; 17:368A, 5. Seifert MJ, Morady F, Calkins HC, et al. Aortic leaflet perforation during radiofrequency ablation, PACE 1992; 14:1582-1585. 6. Brockenbrough EC, Braunwald E. A new technique
1108
7. 8.
9.
10,
11,
August 1992
for left ventricular angiocardiography and transseptal left heart catheterization. Am J Cardiol 1960: 6:1062, Neches WH, Mullins CE, Williams RL, et al. Percutaneous sheath cardiac catheterization. Am J Cardiol 1972; 30:378-384, Van Hare CF, Lesh MD, Scheinman MM, et al. Percutaneous radiofrequency catheter ablation for supraventricular arrhythmias in children. J Am Coll Cardiol 1991; 17:1613-1620, Amar R, Halon DA, Lewis BS, Myocardial damage following coronary air embolism during coronary angiography. Cathet Cardiovasc Diagn 1987; 13:39-41. Kahn JK. Hartzler GO. The spectrum of symptomatic coronary air embolism during balloon angioplasty: Causes, consequences, and management. Am Heart J 1990; 119:1374-1377. Bassand JP, Schiele F, Bernard Y, et al. The doubleballoon and Inoue techniques in percutaneous mitral valvuloplasty: Comparative results in a series of 232 cases, J Am Coll Cardiol 1991; 18:982-989.
PACE, Vol. 15
