Late complications of the atrial baffle operations for

Arterial Switch After Failed Atrial Baffle Procedures for Transposition of the Great Arteries Constantine Mavroudis, MD, and Carl L. Backer, MD Division of Cardiovascular-Thoracic Surgery, Children s Memorial Hospital and Department of Surgery, Northwestern University Medical School, Chicago, Illinois Background. Late failure of the systemic right ventricle after atrial baffle procedures in patients with transposition of the great arteries poses significant management problems. We reviewed our experience with staged conversion to arterial switch operation (ASO) in these patients. Methods. Between 1984 and 1999, 11 patients underwent pulmonary artery band (PAB) to prepare the left ventricle for ASO conversion. One additional patient had subpulmonic stenosis and was naturally prepared. Mean age at the initial PAB was 12.2 7 years (range, 1.9 to 23 years). Four patients underwent reoperation to tighten the PAB before ASO. Mean interval from PAB to ASO was 1.3 0.9 years. Results. There was no mortality from PAB. Six patients had ASO conversion and 2 died. Recent surgical modifications at the time of ASO were used to prevent neoaortic valve insufficiency and to cryoablate atrial reentry tachycardia. Four patients developed biventricular failure after PAB and had orthotopic cardiac transplantation (OCT) 14 10 months after PAB. The other 2 patients are still with PAB: 1 is awaiting ASO conversion and the other has insufficient left ventricular hypertrophy necessary for ASO conversion despite two preparatory PABs. Conclusions. A select group of patients with right ventricular failure after atrial baffle operations can undergo staged conversion to ASO with the opportunity for excellent long-term outcome. Surgical modifications at the time of ASO can address the problems of neoaortic insufficiency and persistent atrial arrhythmias. PAB may be a therapeutic endpoint in some patients not responding with adequate left ventricular hypertrophy. Those patients who develop biventricular failure after PAB will require cardiac transplantation. (Ann Thorac Surg 2000;69:851 7) 2000 by The Society of Thoracic Surgeons Late complications of the atrial baffle operations for transposition of the great arteries (TGA) include right (systemic) ventricular (RV) failure and lifethreatening atrial arrhythmias [1 3]. The idea that the low pressure and underloaded left ventricle (LV) in TGA patients with established atrial baffle operations could be retrained en route to baffle takedown and an arterial switch operation (ASO) was introduced by Mee [4]. This require a series of operations commencing with a preparatory pulmonary artery band(s) (PAB), and eventual ASO. A few centers have documented the clinical results of such a program [5 8] and identified accompanying complications, which can include ineffective induction of LV hypertrophy, neoaortic insufficiency, persistent troubling atrial arrhythmias, and biventricular failure that can lead to cardiac transplantation. The purpose of this article is to report our results with TGA patients with failed atrial baffle procedures who underwent PAB with the intention to treat by ASO conversion after induction of LV hypertrophy. Presented at the Forty-sixth Annual Meeting of the Southern Thoracic Surgical Association, San Juan, Puerto Rico, Nov 4 6, 1999. Address reprint requests to Dr Mavroudis, Division of Cardiovascular- Thoracic Surgery, Children s Memorial Hospital, 2300 Children s Plaza, M/C 22, Chicago, IL 60614-3394; e-mail: c-mavroudis@nwu.edu. Material and Methods Between November 1984 and June 1999, 11 patients with a failed atrial baffle operation for TGA underwent at least one preparatory PAB to induce LV hypertrophy en route to ASO conversion. An additional patient developed subpulmonic stenosis and experienced natural induction of LV hypertrophy. The pre-pab clinical features of the 12 patients are listed in Table 1. There were 8 boys and 4 girls. The mean age at the atrial baffle operation was 6.5 5 months. The mean age at the first preparatory PAB was 12.2 7 years (range, 1.9 to 23 years). The relevant pre-pab catheterization and echocardiographic data are listed in Table 2. The mean pre-pab LV/RV pressure ratio was 0.46 0.22. Surgical Technique Fifteen preparatory PABs (Fig 1) were performed in 11 patients through a left thoracotomy (n 11) or a median sternotomy (n 4). As the PAB was tightened, simultaneous proximal pulmonary arterial (LV) and systemic arterial (RV) pressures were monitored. Transesophageal echocardiography was employed in all patients having PAB after 1995 (n 10) to monitor the effect of PAB on RV This article has been selected for the open discussion forum on the STS Web site: http://www.sts.org/section/atsdiscussion/ 2000 by The Society of Thoracic Surgeons 0003-4975/00/$20.00 Published by Elsevier Science Inc PII S0003-4975(99)01545-3

852 MAVROUDIS AND BACKER Ann Thorac Surg ATRIAL BAFFLE-ARTERIAL SWITCH CONVERSION 2000;69:851 7 Table 1. Clinical Characteristics of Patients With TGA Having Prior Atrial Baffle Procedures and Considered Candidates for ASO Conversion a Status of Patient Patient No. Initial Procedure Age at Atrial Baffle (months) Age at PAB (years) Age at ASO or OCT (years) Other Prior Operations Had ASO 1 Mustard 13 1.9 5.0 2 b Mustard 2 4.8, 5.1 5.7 3 Senning, VSD 6 14.4 15.1 4 Senning, LVOTO 5 12.0 5 Senning 7 13.5 14.2 6 b Mustard, VSD, LVOTO 5 14.5, 16.4 16.8 Needed OCT 7 Mustard, VSD, LVOTO 19 8.6 8.9 TVR 8 Senning, VSD, LVOTO 12 3.7 5.5 TVR, ventricular pacemaker 9 Mustard, VSD 3 14.0, 14.1 14.7 10 Mustard 18 23 25 SVC obstruction, baffle leak, atrial pacemaker Waiting 11 Mustard, VSD, LVOTO 13 18.0, 18.5 Atrial pacemaker 12 Mustard, PS 5 18.0 Total 6 TGA, IVS 6 TGA, VSD 6.5 5.6 c 12.2 7 c 11.5 ASO 13.5 OCT a Eleven patients had RV dysfunction and congestive heart failure. Patient 4 in the ASO group had severe subpulmonic stenosis and was asymptomatic. b Early mortality. c Mean standard deviation. ASO arterial switch operation; IVS intact ventricular septum; LVOTO left ventricular outflow tract obstruction; OCT orthotopic cardiac transplantation; PAB pulmonary artery band; PS pulmonary stenosis; RV right ventricular; SVC superior vena cava; TGA transposition of the great arteries; TVR tricuspid valve replacement; VSD ventricular septal defect. and LV function, septal deviation, and improvement (if any) of tricuspid regurgitation. A dopamine infusion was started intraoperatively (5 to 10 g kg 1 min 1 ) and sodium bicarbonate was administered as necessary to treat the metabolic acidosis that usually accompanies this procedure [9]. All patients underwent controlled ventilation for 24 to 72 hours after PAB while initial ventricular adaptation was occurring. A second operation to tighten the PAB was performed in 4 patients using the same operative approach and protocols. The atrial baffle takedown (Figs 2 5) and ASO was performed in 6 patients with the usual techniques required for resternotomy, careful dissection, conscientious myocardial preservation (antegrade and retrograde cold blood cardioplegia), coronary transfer, and great vessel reconstruction. The PAB was removed and the neopul- Table 2. Cardiac Catheterization Data Before PAB Status of Patient Patient No. LVP RVP LV/RV Ratio TR (ECHO) LVPW Thickness (ECHO) (mm) LV Function Had ASO 1 40 80 0.5 3 4 3 2 a 30 100 0.3 3 4 1 3 72 130 0.6 3 8 3 4 130 130 1.0 0 7 3 5 22 120 0.2 2 6 3 6 a 54 95 0.6 2 6 3 Needed OCT 7 51 95 0.5 TVR 5 2 8 TVR 3 2 9 40 105 0.4 3 4 3 10 40 120 0.3 2 3 Waiting 11 30 125 0.2 2 4 2 12 40 80 0.5 1 5 3 Mean SD 49.9 29.8 107.3 18.8 0.46 0.22 2.1 0.9 5.1 1.5 2.6 0.6 a Early mortality. ASO arterial switch operation; ECHO echocardiography; LV left ventricular; LV Function (1 moderately depressed; 2 mildly depressed; 3 normal); LVP left ventricular pressure (systolic); LVPW left ventricular posterior wall; OCT orthotopic cardiac transplantation; PAB pulmonary artery band; RV right ventricular; RVP right ventricular pressure (systolic); SD standard deviation; TR tricuspid regurgitation (0 none; 1 mild; 2 moderate; 3 severe); TVR tricuspid valve replacement.

Ann Thorac Surg MAVROUDIS AND BACKER 2000;69:851 7 ATRIAL BAFFLE-ARTERIAL SWITCH CONVERSION 853 Fig 1. Representation of instrumentation and interventricular septal geometry before (A) and after (B) preparatory pulmonary artery band (PAB) in a patient with transposition of the great arteries after a failed atrial baffle procedure. The proximal pulmonary artery pressure is measured simultaneously with the systemic pressure. As the band is tightened, a rise in left ventricular (LV) pressure is noted, which is accompanied by an interventricular septal shift toward the right ventricle (RV; monitored by transesophageal echocardiography). This oftentimes results in improved tricuspid valve function and less tricuspid regurgitation (TR). Bold arrow represents severe TR, small arrow after PAB represents mild TR. Fig 3. Right atrial view in a patient with an established Senning baffle operation for transposition of the great arteries undergoing baffle takedown. Care is taken to preserve the sinoatrial node and the original baffle connections for eventual reconnection to the posterior right atrial wall. monary artery was reconstructed with cryopreserved homograft pericardium. Additional modified techniques were employed to prevent neoaortic insufficiency by Hemashield (Meadox Medicals Inc, Oakland, NJ) neoaortic valve-sparing reconstruction in 3 patients (Fig 6) [10], aortic homograft insertion in 1 patient (Fig 7), and subsequent neoaortic valve replacement in 1 patient who did not have a modified neoaortic valve repair. Atrial arrhythmias were treated concomitantly in 2 patients with cryoablation techniques [11]. Cardiac transplantation was performed in 4 patients who developed severe biventricular dysfunction after PAB. Anatomic modification at the time of cardiac transplantation included Mustard baffle excision with atrial septal recreation in 1 patient, Senning baffle takedown and atrial septal recreation in 1 patient [12], and more recently, Mustard baffle takedown with bicaval anastomoses in the other 2 patients. Two recent patients had preparatory PAB and are Fig 2. Right atrial view in a patient with an established Mustard baffle operation for transposition of the great arteries undergoing baffle excision en route to arterial switch operation conversion. Care is taken to remove the entire atrial baffle (outlined by dashed line) without injuring the superior vena cava, the inferior vena cava, and the sinoatrial node. A coronary sinus catheter is placed for retrograde cardioplegia delivery. Fig 4. Right atrial view in a patient who had Senning baffle takedown and is now undergoing baffle reconnection to the right posterolateral atrial wall en route to Gore-Tex (W.L. Gore & Assoc, Flagstaff, AZ) atrial septum reconstruction and arterial switch operation conversion.

854 MAVROUDIS AND BACKER Ann Thorac Surg ATRIAL BAFFLE-ARTERIAL SWITCH CONVERSION 2000;69:851 7 Fig 5. Right atrial view in a patient who had Mustard baffle excision and is now undergoing a right-sided Maze cryoablation procedure and Gore-Tex (W.L. Gore & Assoc, Flagstaff, AZ) reconstruction of the atrial septum. Lines of block are created to connect the inferoposterior os of the coronary sinus with the inferior vena cava, the edge of the atrial septal defect with the posterior atrial wall across the crista terminalis, and the atrial septal defect with the edge of the right atrial appendage. The Gore-Tex patch is placed to divide the anatomic left and right atria. Fig 7. Aortic homograft implantation in a patient who had a Senning operation for transposition of the great arteries and moderate pulmonary stenosis. The patient underwent a preparatory PAB en route to arterial switch operation conversion by neoaortic reconstruction using an aortic homograft because of the poor quality of the existing pulmonary valve (neoaortic valve). presently being evaluated for ASO conversion based on LV posterior wall thickness, LV pressure, and LV function. LV Evaluation Before ASO Assessment of an adequately prepared LV after PAB was made by echocardiography and cardiac catheterization. Measurements included assessment of biventricular function, LV posterior wall thickness, and LV systolic pressure. In general, patients were referred for ASO conversion when the LV diastolic posterior wall measurement was more than 8 mm thick and when the LV systolic pressure was more than 80% of the RV (systemic) pressure with a well-functioning LV. Clinical Evaluation Before Cardiac Transplantation Patients became candidates for cardiac transplantation if they did not respond favorably to the preparatory PAB. They were deemed to have end-stage congenital heart disease based on poor systemic ventricular function, deteriorating functional class, and an estimated life expectancy of less than 6 months. None of these patients developed an increase in their LV posterior wall thickness. All of these patients were hospitalized for inotropic support before cardiac transplantation. Follow-up was complete in all patients. Results are expressed as mean standard deviation (SD). Fig 6. Hemashield (Meadox Medicals Inc, Oakland, NJ) neoaortic valve-sparing reconstruction used to prevent proximal neoaortic dilatation and resultant neoaortic insufficiency. The pulmonary artery wall is removed and the contoured Hemashield graft is sewn into the resected sinuses of Valsalva. Appropriately sized holes are made in the corresponding facing sinuses for coronary reimplantation. The distal Hemashield graft is sutured end to end into the ascending aorta, thereby reconstructing the neoaorta. Results Mortality in this series of operations is categorized by procedure: PAB, ASO, and orthotopic cardiac transplantation (OCT). Eleven patients had 15 preparatory PAB procedures without operative mortality. There were 2 early deaths (33%) and no late deaths in the 6 patients in the ASO group. There were no early deaths in the OCT

Ann Thorac Surg MAVROUDIS AND BACKER 2000;69:851 7 ATRIAL BAFFLE-ARTERIAL SWITCH CONVERSION 855 Table 3. Post-PAB Ventricular Pressure Data Intraoperative Data Post-PAB Pre-ASO Status of Patient Patient No. LVP RVP LV/RV Ratio LVP RVP LV/RV Ratio Had ASO 1 70 90 0.8 85 95 0.9 2 a 80 120 0.7 100 100 1.0 3 110 120 0.9 94 100 0.9 4 No PAB 130 130 1.0 5 69 143 0.5 116 125 0.9 6 a 80 110 0.7 80 90 0.9 Had OCT 7 65 90 0.7 65 90 0.7 8 60 100 0.6 50 100 0.5 9 100 130 0.8 75 110 0.7 10 44 100 0.4 52 108 0.5 Waiting 11 75 106 0.7 69 119 0.6 12 70 112 0.6 58 90 0.6 a Early mortality. ASO arterial switch operation; LV left ventricular; LVP left ventricular pressure (systolic); OCT orthotopic cardiac transplantation; PAB pulmonary artery band; RV right ventricular; RVP right ventricular pressure (systolic). group and 1 late death 7 years after OCT from chronic rejection. The 2 deaths in the ASO group were related to an error in judgment in 1 patient and unanticipated postoperative LV dysfunction in the other. The error in judgment occurred intraoperatively when a presumed single coronary artery was transferred. Postmortem examination revealed the presence of another (untransferred) paracommissural coronary artery and myocardial infarction. The other death occurred in a 17-year-old boy who had two previous preparatory PABs. Before ASO his LV/RV pressure ratio was 0.9, with an LV pressure of 80 mm Hg. He had baffle takedown, a right-sided Maze operation for atrial arrhythmias, and ASO combined with Hemashield neoaortic valve-sparing reconstruction. He required placement of a LV assist device (Thoratec Laboratories Corp, Berkeley, CA) 12 hours after repair for low cardiac output and ventricular arrhythmias and eventually died 2 weeks postoperatively from a cerebral infarct and intracranial bleed. Postmortem examination revealed that the LV posterior wall had 7 mm of muscle and 3 mm of fibrous tissue (not 10 mm of muscle). His postoperative LV failure was probably because of inadequate LV hypertrophy. The intraoperative and postoperative pressure measurements in those patients who had preparatory PAB are listed in Table 3. Comment As patients with atrial baffle operations for TGA become older, the therapeutic dilemma involving RV dysfunction, tricuspid regurgitation, and troubling atrial arrhythmias becomes more problematic. The first problem is to identify suitable candidates for potential ASO conversion who are not overly symptomatic and still have some reserve to sustain the often multiple operations that are necessary for anatomic correction. The next problem is to define the upper and lower inclusionary criteria for operation. Obviously, there are patients who are too sick at their initial presentation for this therapy. Also, there are a number of asymptomatic patients with a variety of echocardiographic and catheterization findings who may or may not be progressing toward eventual ventricular dysfunction. Some of these patients might benefit from such an operative program. Of course, the other arm of therapy is to manage these patients medically until the time comes for OCT, assuming that unmanageable pulmonary hypertension does not intervene. Many of these issues are beyond the scope of our limited experience, however, the results of this and other clinical reports may shed some light on the evolving therapy for TGA patients who were treated with atrial baffle operations. Preparatory PAB was successful in inducing the necessary LV hypertrophy and LV pressure for ASO conversion in some but not all of our patients. There seems to be an age-dependent time when preparatory PAB has a smaller chance of resulting in successful anatomic correction. Although all of our successful ASO patients were less than 16 years of age, 2 of our PAB patients who required OCT were 6 and 9 years of age. Our 1 patient who died because of an inadequately prepared LV was 17 years old. There seems to be little trouble in inducing LV hypertrophy in infants with unoperated TGA who have aged beyond the neonatal period by PAB and systemicto-pulmonary artery shunt [13, 14]. Why this is not true in older children may be related to two factors. First, the neonatal heart, unlike the older child s heart, has the ability to undergo myocyte hyperplasia for several months, which favors myocardial mass development [15]. Second, the child s heart with a failed atrial baffle operation often has some degree of biventricular failure, which may respond unfavorably to PAB and LV retraining. In our series the mean age at PAB was 12.2 years, the mean age at ASO was 11.5 years, and the mean age at OCT was 13.5 years. In the review by Prieto and colleagues [8], older age was a significant risk factor for mortality: mean ages for survivors and nonsurvivors

856 MAVROUDIS AND BACKER Ann Thorac Surg ATRIAL BAFFLE-ARTERIAL SWITCH CONVERSION 2000;69:851 7 were 11.0 4.8 vs 15.8 5.1 years, respectively. However, Cetta and associates [16] reported successful ASO conversion in a 36-year-old patient. In general, we would conclude from our data and clinical review that the older the patient, especially older than 16 years of age, the less likely ASO conversion will be. A small subgroup of patients may be able to have successful ASO conversion without a preparatory PAB. We had 1 such patient in our series, a 12-year-old patient who had progressive subpulmonic obstruction and natural occurrence of LV hypertrophy. Several centers have reported successful one-stage arterial switch, often in the setting of pulmonary venous obstruction, which creates pulmonary hypertension and in effect prepares the LV serendipitously [16 18]. The technical aspects of our series are interesting because we have addressed the problems of resultant neoaortic insufficiency and troubling atrial arrhythmias at the time of ASO. Five of our 6 patients who eventually had ASO had some kind of neoaortic valve reconstruction at the initial operation (n 4) or aortic valve replacement later because of neoaortic regurgitation (n 1). So far, neoaortic insufficiency has not occurred in the patients who had neoaortic reconstruction at the initial operation. Whether this will be maintained over time and whether this approach will compare favorably with those patients who did not have modified neoaortic reconstruction remain to be evaluated. Cochrane and colleagues [6] reported 2 of 16 patients having ASO conversion requiring aortic valve replacement (12%) and 5 other patients (31%) having mild aortic insufficiency under observation. Chang and coworkers [7] reported a high incidence of neoaortic insufficiency after anatomic correction, and 1 of their 5 patients required an aortic valve replacement 4 months after ASO. There was hope during the initial evaluation of this strategy that once the ASO was performed, the atrial pressures would decrease and this would be accompanied by a resolution of atrial arrhythmias. This has proved not to be the case. As a result, we instituted a strategy to evaluate for atrial arrhythmias and to perform arrhythmia operations when appropriate. This strategy, which we have applied in other patients [11], has been successful in our 2 patients with nodal reentry tachycardia and atrial reentry tachycardia, respectively. Four patients in this series required OCT after PAB because of biventricular failure. The mean age of these patients at OCT was 13.5 7 years. One of those patients died 7 years posttransplant from chronic rejection. OCT has been reported in many patients with end-stage congenital heart disease, including those with failed atrial baffle procedures [7, 12]. In our series these patients tended to have had other prior procedures tricuspid valve replacement (2), pacemaker (2), superior vena cava obstruction (1) and were not as easy to obtain a reasonable LV pressure at the time of PAB. There is a subset of failed atrial baffle procedure patients that undergoes preparatory PAB resulting in improved functional class without sufficient LV hypertrophy induction or LV pressure for ASO conversion. The patients in this subset may improve their hemodynamic status because of induction of LV hypertrophy and septal deviation toward the midline resulting in more favorable geometric conditions for tricuspid valve function and improved ventricular contractility. These findings have been reported previously [5, 6] and are consistent with our results. We have 1 patient who had two PABs over a 2.5-year period who did not develop sufficient LV pressure or hypertrophy to undergo ASO. She has, however, experienced increased functional class because of improved RV function and decreased tricuspid valve regurgitation. One has to consider whether PAB in a subset of these patients will represent a therapeutic endpoint. Unfortunately, the needed and resolving prospective trial is unlikely to be performed. In many ways this is a diminishing problem as the current standard of care for patients with TGA is neonatal arterial switch. However, the large number of patients with extant atrial baffle operations will require some attention in the future. This makes small series like this and others like it all the more important to document the results and discuss the options that are likely to present themselves. A select group of patients with RV failure after atrial baffle operations can undergo staged conversion to ASO with the opportunity for excellent long-term cardiac function. Surgical modifications can address the problems of neoaortic insufficiency and persistent atrial arrhythmias. Some PAB patients will improve symptomatically but will not develop sufficient LV hypertrophy for ASO conversion. Whether PAB will represent a therapeutic endpoint in these patients remains to be seen. Those patients who develop biventricular failure after PAB will require cardiac transplantation. References 1. Turina MI, Siebenmann R, von Segesser L, Schönbeck M, Senning A. Late functional deterioration after atrial correction for transposition of the great arteries. Circulation 1989; 80(3 Pt 1):I162 7. 2. Gelatt M, Hamilton RM, McCrindle BW, et al. Arrhythmia and mortality after the Mustard procedure: a 30-year singlecenter experience. J Am Coll Cardiol 1997;29:194 201. 3. Kirjavainen M, Happonen JM, Louhimo I. Late results of Senning operation. J Thorac Cardiovasc Surg 1999;117: 488 95. 4. Mee RBB. Severe right ventricular failure after Mustard or Senning operation. Two-stage repair: pulmonary artery banding and switch. J Thorac Cardiovasc Surg 1986;92: 385 90. 5. Van Son JAM, Reddy VM, Silverman NH, Hanley FL. Regression of tricuspid regurgitation after two-stage arterial switch operation for failing systemic ventricle after atrial inversion operation. J Thorac Cardiovasc Surg 1996;111: 342 7. 6. Cochrane AD, Karl TR, Mee RBB. Staged conversion to arterial switch for late failure of the systemic right ventricle. Ann Thorac Surg 1993;56:854 62. 7. Chang AC, Wernovsky G, Wessel DL, et al. Surgical management of late right ventricular failure after Mustard or Senning repair. Circulation Suppl 1992;86(Suppl 2):140 9. 8. Prieto LR, Latson LA, Flamm SD, Drummond-Webb J, Mee RBB. Conversion from atrial to arterial switch in patients with D-transposition of the great arteries: risk factors for mortality [Abstract]. Circulation 1998;17:I61.

Ann Thorac Surg MAVROUDIS AND BACKER 2000;69:851 7 ATRIAL BAFFLE-ARTERIAL SWITCH CONVERSION 857 9. Wernovsky G, Giglia TM, Jonas RA, Mone SM, Colan SD, Wessel DL. Course in the intensive care unit after preparatory pulmonary artery band and aortopulmonary shunt placement for transposition of the great arteries with low left ventricular pressure. Circulation Suppl 1992;86(Suppl II): 133 9. 10. David TE, Feindel CM. An aortic valve-sparing operation for patients with aortic incompetence and aneurysm of the ascending aorta. J Thorac Cardiovasc Surg 1992;103:617 22. 11. Mavroudis C, Backer CL, Deal BJ, Johnsrude CL. Fontan conversion to cavopulmonary connection and arrhythmia circuit cryoablation. J Thorac Cardiovasc Surg 1998;115: 547 56. 12. Backer CL, Zales VR, Mavroudis C. Heart transplantation in the infant and child. In: Mavroudis C, Backer CL, eds. Pediatric cardiac surgery, 2nd ed. St. Louis: Mosby Yearbook, Inc, 1994:571 83. 13. Boutin C, Wernovsky G, Sanders SP, Jonas RA, Castañeda AR, Colan SD. Rapid two-stage arterial switch operation evaluation of left ventricular systolic mechanics late after an acute pressure overload stimulus in infancy. Circulation 1994;90:1294 303. 14. Boutin C, Jonas RA, Sanders SP, Wernovsky G, Mone SM, Colan SD. Rapid two-stage arterial switch operation acquisition of left ventricular mass after pulmonary artery banding in infants with transposition of the great arteries. Circulation 1994;90:1304 9. 15. Sonnenblick EH, Anversa P. Models and remodeling: mechanisms and clinical implications. Cardiologia 1999;44:609 19. 16. Cetta F, Bonilla JJ, Lichtenberg RC, Stasior C, Troman JE, DeLeon SY. Anatomic correction of dextrotransposition of the great arteries in a 36-year-old patient. Mayo Clin Proc 1997;72:245 7. 17. Shinebourne EA, Jahangiri M, Carvalho JS, Lincoln C. Anatomic correction for post-mustard pulmonary venous obstruction. Ann Thorac Surg 1994;57:1655 6. 18. Reisman M, Rosengart RM, Degner TL, Sintek C, Khonsari S. Post-Mustard procedure pulmonary venous obstruction: an opportunity for anatomic correction with a one-stage arterial switch. Pediatr Cardiol 1999;20:301 3. DISCUSSION DR KIT V. AROM (Minneapolis, MN): Since given the large number of Mustard patients who are doing extremely well, which of these patients are likely to benefit from this therapy? DR MAVROUDIS: There are many patients with Mustard baffles who are doing reasonably well and may in fact have been lost to follow-up. In light of the varied clinical outcomes, it is important for pediatric cardiologists to return these patients and evaluate them for symptoms and exercise intolerance. In those patients who did not have symptoms, a diagnostic inquiry may reveal developed subpulmonic stenosis, which may represent an opportunity for a one-stage arterial switch conversion, even in the absence of symptoms. This approach admittedly is quite involved but successful in those patients who are well prepared. Thank you very much for your question. DR ROSS M. UNGERLEIDER (Durham, NC): Gus, I appreciated having had the opportunity to review your manuscript. It is extremely well written and I think the readers of the Annals will enjoy having the opportunity to look at all the data. You have clearly made a career of showing all of us that very complex and difficult patients can be treated successfully and you continue to make wonderful contributions to the field. I think that there are two contributions from your experience with this difficult group of patients. One is to recognize the problems that they have with neoaortic insufficiency, clearly a problem that was demonstrated in the era when patients received pulmonary artery bands before going to switch, and you have shown us ways to deal with that. You have also addressed the other major issue that brings patients late after atrial baffle operations to medical attention, and that is the development of arrhythmias, and you have added some very sophisticated treatment of that. As we leave here we have to have a protocol in mind of what to do with these patients, and there is a bit of a conundrum, because it seems that as patients get older, they are worse candidates for conversion with pulmonary artery banding, and I would like to have you address what you would do with these older patients. Patients over 16 years of age in particular have less likelihood of being able to successfully convert to being candidates for an arterial switch, yet if you think about the era that we are in, there are very few patients in the past 16 years who have received atrial baffle operations. And so in a way you have developed a series of treatments for patients that none of us are likely to see anymore. It is unlikely that we will see younger patients with failed atrial baffle operations who will be good candidates for this. So what do you do in your practice when you see a patient over the age of 16, the patients we are most likely to encounter, the ones who are most likely to be bad candidates for this, what is your protocol? Do you band them anyhow in the hopes that you may occasionally be able to convert one to an atrial switch or do you give them a transplant? DR MAVROUDIS: Thank you for your question. You are quite right that age over 16 years in these patients has been determined to be a risk factor for death. Left ventricular function may be an important prognostic indicator for survival both before and after the pulmonary artery band and should be critically evaluated despite the patient s age. Of course, the only subsequent alternative is cardiac transplantation, which will be a significant part of the therapy in these patients. DR W. STEVES RING (Dallas, TX): My question is really an extension of Ross s. For patients who present with severe right heart failure, often with severe tricuspid or systemic AV valve insufficiency, how do you decide which patients to band and switch versus transplant? DR MAVROUDIS: I think that we would look at left ventricular function in these patients. If left ventricular function were favorable, then we would proceed with the pulmonary artery band despite the degree of right ventricular dysfunction and tricuspid regurgitation. Of course, we can then evaluate the effect of pulmonary artery banding on left ventricular function and proceed accordingly. Thus far, we have had no mortality from pulmonary artery band and we believe that our approach is reasonable.