Optimal management of infants with pulmonary atresia

Transcription

1 Staged Biventricular Repair of Pulmonary Atresia or Stenosis With Intact Ventricular Septum Shunji Sano, MD, Kozo Ishino, MD, Masaaki Kawada MD, Emi Fujisawa, MD, Masahiro Kamada, MD, and Shin-ichi Ohtsuki, MD Departments of Cardiovascular Surgery and Pediatrics, Okayama University Medical School, Okayama, Japan Background. Since 1991 we have performed a multistage palliative approach to biventricular repair of pulmonary atresia or critical pulmonary stenosis with intact ventricular septum in infants with a detectable right ventricular infundibulum. Methods. A total of 25 patients (19 pulmonary atresia and 6 critical pulmonary stenosis) underwent initial palliation consisting of a transarterial pulmonary valvotomy and a polytetrafluoroethylene shunt between the left subclavian artery and pulmonary trunk. Among the 23 survivors, 15 underwent balloon valvotomy. Six of these patients later required additional palliative surgery that consisted of repeat pulmonary valvotomy, adjustment of an atrial communication, and resection of the hypertrophied muscles in the right ventricle. Results. Of the 25 patients, 23 (92%) survived. In all, 20 patients underwent definitive operations: 18 (90%) biventricular repair (12 pulmonary atresia, and 6 critical pulmonary stenosis), one bidirectional Glenn, and one Fontan procedure. The actuarial probability of achieving a biventricular repair at 36 months of age was 69%. In 18 patients right ventricular end diastolic volume significantly increased but tricuspid valve diameter did not change. Conclusions. The multistage palliation procedure to promote right ventricular growth makes a definitive biventricular repair of pulmonary atresia or critical pulmonary stenosis with intact ventricular septum possible in the majority of infants with a patent infundibulum. (Ann Thorac Surg 2000;70:1501 6) 2000 by The Society of Thoracic Surgeons Optimal management of infants with pulmonary atresia and intact ventricular septum has been controversial because of the anatomical heterogeneity of the hearts exhibiting this disorder [1]. The tripartite right ventricular desciption by Goor and Lillehei [2] and the revised classification by Bull and colleagues [3] have provided logical means for determining appropriate palliative and definitive repairs. However, there are still significant associated anomalies such as myocardial sinusoid, stenosis or interruption of coronary arteries, and Ebstein s malformation of the tricuspid valve, which influence surgical outcome. Several studies [4 7] have demonstrated that a hypoplastic right ventricle with a patent infundibulum in pulmonary atresia or critical pulmonary stenosis with intact ventricular septum has long-term growth potential when continuity between the right ventricular cavity and pulmonary artery is established. In this subset of patients, therefore, a two-ventricle circulation is likely in the future if satisfactory palliation provides adequate pulmonary blood flow and maximizes the development of the right heart. Since 1991, our institutional bias has been to perform a pulmonary valvotomy and systemic pulmonary artery shunt as initial palliation toward an eventual biventricular repair in all infants with detectable infundibula, regardless of right ventricular size, tricuspid valve diameter, or the existence of sinusoidal coronary artery communication. Patients and Methods Patient Population Between March 1991 and July 1999, 25 consecutive infants (15 boys and 10 girls) underwent transarterial pulmonary valvotomy and received a systemic pulmonary artery shunt as an initial palliation procedure for pulmonary atresia with intact ventricular septum or critical pulmonary stenosis. The median age at operation was 19 days (range, 4 to 98 days) and the median weight was 2.9 kg (range, 1.8 to 3.8 kg). Patients with critical pulmonary stenosis had suprasystemic pressures in the right ventricle, a pinhole patency of the pulmonary valve, and duct-dependent pulmonary circulation. In all other respects they were similar to those patients with pulmonary atresia. All patients were treated with prostaglandin E 1 infusion, and 21 patients underwent balloon atrial septostomy before surgery. One patient had a chromo- Presented at the Thirty-sixth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL Jan 31 Feb 2, Addres reprint requests to Dr Sano, Department of Cardiovascular Surgery, Okayama University Medical School, Shikata-cho, Okayama-City , Japan; s sano@cc.okayama-u.ac.jp. This article has been selected for the open discussion forum on the STS Web site: by The Society of Thoracic Surgeons /00/$20.00 Published by Elsevier Science Inc PII S (00)

2 1502 SANO ET AL Ann Thorac Surg BIVENTRICULAR REPAIR OF PULMONARY ATRESIA/STENOSIS 2000;70: somal abnormality: CATCH 22 syndrome (Cardiac defects, Abnormal facies, Thymic hypoplasia, Cleft palate, Hypocalcemia-22q 11 deletion). Preoperative Evaluation Upon arrival at Okayama University Hospital, all patients underwent detailed echocardiographic examination and cardiac catheterization. Direct measurements obtained during catheterization were used to estimate the right and left ventricular systolic pressure (RVP/LVP) ratio. The right ventricular morphology was analyzed angiographically according to the tripartite approach [2, 3]. A total of 19 patients had pulmonary atresia with a detectable infundibulum of the right ventricle and 6 had critical pulmonary stenosis. Myocardial sinusoidal coronary artery communications were identified in 8 pulmonary atresia patients. One of these seemed to be significant, ie, resulting in right ventricle dependent coronary circulation. None of the infants had angiographic evidence of an interrupted left anterior descending coronary artery. Associated anomalies included an unroofed coronary sinus in 1 patient and a partial anomalous pulmonary venous connection and cor triatriatum in another. Right ventricular volumes were calculated from biplane cineangiograms using Simpson s rule as previously described [8]. Right ventricular end diastolic volume (RVEDV) was corrected for body surface area and was expressed as a percentage of the predicted normal using the formula derived by Nakazawa and colleagues [9]. Predicted normal RVEDV ml 75.1 BSA m The tricuspid valve diameter was measured from echocardiograms at its maximum in diastole from the apical four-chamber view and was used to calculate the tricuspid valve circumference. This calculated value was then expressed as a percentage of the normal mean obtained with the formula from postmortem data by Rowlatt and associates [10]. Normal mean circumference mm { log [ BSA(m 2 ) 10,000] } 10 The tricuspid valve diameter was also expressed as a Z-value using a nomogram [11]. In the 25 patients, mean values of RVP/LVP ratio, RVEDV, tricuspid diameter, and its Z-zalue were 1.42 (range, 0.43 to 2.05), 48% of predicted normal (range, 15% to 123%), 77% of normal mean (range, 30% to 117%), and 1.4 (range, 4.4 to 2.3), respectively. Tricuspid valve regurgitation was graded as none, mild, moderate, or severe by color flow Doppler echocardiography as follows: mild if the regurgitant jet was detected in less than one third of the area of the right atrium; moderate if detected in more than one third but in less than two thirds; and severe if detected in more than two thirds of the right atrium [12]. Ten patients (40%), including two patients with Ebstein s anomaly, had severe tricuspid regurgitation, five (20%) had moderate regurgitation, and three (12%) had mild regurgitation. Initial Surgical Palliation All patients underwent a transarterial pulmonary valvotomy and a systemic pulmonary shunt without cardiopulmonary bypass, as previously reported by Joshi and coworkers [13]. Through a left lateral thoracotomy at the fourth intercostal space, the pericardium was opened anterior to the left phrenic nerve. A pursestring suture with a tourniquet was placed on the pulmonary trunk, which was then cross-clamped just proximal to its bifurcation. An incision was made in the pursestring and the atretic pulmonary valve was incised with a knife under direct vision. The tourniquet was rapidly cinched closed to control bleeding. The pulmonary valve was further opened using a 3-mm or 4-mm Hegar dilator through the incision, with the hemostasis secured by the tourniquet. After this, a 4-mm polytetrafluoroethylene tube (Gore- Tex tube, W.L. Gore & Associates, Inc, Flagstaff, AZ) was anastomosed to the left subclavian artery and the incision in the pulmonary trunk. The ductus arteriosus was then ligated. All patients survived and were discharged from the hospital. During follow-up, 1 child developed sudden desaturation and underwent emergency bidirectional Glenn anastomosis at another hospital. There were two late deaths; 1 patient died suddenly at home at 4 months of age and the other died from hepatic failure after an additional right modified Blalock-Taussig shunt at 12 months of age. Balloon Pulmonary Valvotomy A total of 22 patients had diagnostic postoperative cardiac catheterizations after a mean interval of 9 months (range, 3 to 26 months). Since 1995 we have performed this catheterization earlier to assess results of the initial surgery, and the mean interval in the last 12 patients was 6 months. At this stage, a RVP/LVP ratio was greater than 0.5 in all but 1 patient. Thus, 17 patients underwent a balloon pulmonary valvotomy, but the right ventricular cavity was too small for passage of a balloon catheter in the remaining 4 patients. Secondary Surgical Procedure The second-stage surgical palliation was indicated when a RVEDV was less than 50% of predicted normal value estimated at the last cardiac catheterization, and was performed in 6 patients at a median age of 13 months (range, 5 to 24 months). The operative procedure used was similar to that reported as a right ventricular overhaul by Pawade and associates [14]: repeat pulmonary valvotomy, transatrial and transpulmonary resection of hypertrophied infundibular muscle, and adjustment of an interatrial communication (Fig 1). To increase blood flow through the tricuspid valve, we partially closed the atrial septal defects, keeping right atrial pressures of less than 15 mm Hg and a gradient across the atrial septal defect of less than 10 mm Hg. Pulmonary arteriotomies were directly closed. All patients tolerated the operations well, but 1 child suffered from severe right

3 Ann Thorac Surg SANO ET AL 2000;70: BIVENTRICULAR REPAIR OF PULMONARY ATRESIA/STENOSIS 1503 Fig 1. The second palliative operation (right ventricular overhaul [14]) included repeat pulmonary valvotomy, enlargement of right ventricular cavity, and adjustment of an interatrial communication. Shaded areas show excised hypertrophic muscles within the trabecular and infundibular portions. ventricular failure and subsequently underwent a bidirectional Glenn anstomosis on postoperative day 9. Statistical Methods The obtained data were analyzed using SPSS software (SPSS Inc, Chicago, IL). The data are expressed as means plus or minus standard deviations, and proprtional data are presented with their 95% confidence intervals (CI). The Wilcoxon signed rank test was used for comparison of continuous variables. Actuarial survival and probability of biventricular repairs were computed by Kaplan- Meier methods. The level of statistical significance was set as a p value of less than Fig 2. Actuarial probability of a biventricular repair in 25 patients with a patent infundibulum. Vertical bars enclose a 95% confidence interval. 53% 32% of the predicted normal before initial palliation to 88% 41% at the time of the last catheterization before biventricular repair (p ), whereas the RVP/LVP ratio (Fig 4) decreased from to (p ). The tricuspid valve diameter (Fig 5) before initial palliation did not change as compared to the diameter before biventricular repair (84% 22% of the normal mean vs 83% 17%, p not significant [NS]), although its Z-value (Fig 6) decreased from to (p 0.012). Of the 8 patients who had sinusoidal-coronary artery communications before the initial palliation procedure, 3 patients underwent biventricular repair, 2 are awaiting Results Biventricular repair was achieved in 18 patients (12 patients with pulmonary atresia and all 6 with critical pulmonary stenosis) at a median age of 28 months (range, 15 to 55 months). Two patients had previously undergone a right ventricular overhaul. Except for 1 patient who had coil embolization of systemic pulmonary shunt after spontaneous closure of the atrial septal defect, all patients underwent pulmonary valvotomy, enlargement of the right ventricle by resection of hypertrophied muscles, closure of the atrial septal defect, and division of the systemic pulmonary shunt. Additional procedures included tricuspid valvular repair in 9 patients and right ventricular outflow reconstruction with a monocuspid autologous pericardial patch in 7 patients, and repair of the unroofed coronary sinus in 1 patient. There were no in-hospital or late deaths. The remaining 3 patients underwent the second surgical palliation and are awaiting evaluation for biventricular repair. The actuarial probability of obtaining a biventricular repair at 36 months of age was 69% (95% CI 48% to 89%, Fig 2). In the 18 patients, the RVEDV (Fig 3) increased from Fig 3. Change in right ventricular end diastolic volume (RVEDV) expressed as a percentage of the predicted normal. (* p as compared with values before initial palliation. Means standard deviations.)

4 1504 SANO ET AL Ann Thorac Surg BIVENTRICULAR REPAIR OF PULMONARY ATRESIA/STENOSIS 2000;70: Fig 4. Change in right and left ventricular systolic pressure (RVP/ LVP) ratio. (* p as compared with values before initial palliation. Means standard deviations.) evaluation, 2 received bidirectional Glenn anastomoses, and 1 died. None of the 3 patients whose tricuspid valve Z-value was less than 4 underwent biventricular repair. As of our most recent echocardiographic follow-up, tricuspid valve regurgitation was severe in 3 patients, moderate in 7, and mild in 5. The current status of the 25 infants who underwent pulmonary valvotomy and systemic pulmonary shunt as an initial palliation is shown in Figure 7. Of the 2 patients requiring bidirectional Glenn anastomosis after palliative surgery, 1 subsequently underwent a Fontan operation. The actuarial survival for all 25 patients was 92% (95% CI 81% to 100%) at 12 months, with no further deaths over the 100-month follow-up period (Fig 8). Fig 6. Change in Z-value of the tricuspid valve. (* p as compared with values before initial palliation. Means standard deviations.) Comment Despite improvement over the past 30 years in the treatment of infants with pulmonary atresia and intact ventricular septum, mortality and morbidity remain significant [15 17]. Since the introduction of the tripartite classification of right ventricular morphology [2, 3], attempts have been made to define anatomic criteria preoperatively that can guide decisions regarding surgical intervention and can provide prognostic indicators for survival. At present the infundibulum is the focus of preoperative assessment. Namely, if an infundibular portion is identified, a trabecular portion is usually present despite severe muscular hypertrophy; this fact signifies the ability of a hypoplastic right ventricle to grow. Thus, our Fig 5. Change in tricuspid diameter expressed as a percentage of the normal mean. (Means standard deviations.) Fig 7. Intermediate outcome of 25 infants who underwent the combined pulmonary valvotomy and systemic pulmonary shunt as a initial palliation for pulmonary atresia or critical pulmonary stenosis with intact ventricular septum. (BDG bidirectional Glenn).

5 Ann Thorac Surg SANO ET AL 2000;70: BIVENTRICULAR REPAIR OF PULMONARY ATRESIA/STENOSIS 1505 Fig 8. Actuarial survival for the entire study group of 25 patients. Vertical bars enclose a 95% confidence interval. surgical decision making is currently based entirely on the presence or absence of the infundibulum. Therapy for pulmonary atresia or critical pulmonary stenosis centers first on providing adequate pulmonary blood flow and, second, on maximizing the development of the right heart. Nevertheless, important questions persist as to how and when to decompress the right ventricle. With the staged palliation procedure used in this study, satisfactory growth with gradual decompression of the right ventricle was achieved, and 90% of patients who had definitive operations subsequently underwent biventricular repair. Establishment of right ventricular pulmonary artery continuity and adequate pulmonary blood flow during the neonatal period is essential to right ventricular growth. We, as well as others [4, 13], believe that this is best accomplished by transarterial valvotomy and systemic pulmonary shunting. Transarterial valvotomy [4, 13] is preferable to transventricular valvotomy [5, 6] or right ventricular outflow patching [18, 19] because it does not damage neonatal hearts and makes more accurate valvotomy possible. In addition, it can be safely performed without cardiopulmonary bypass. Adequate right ventricular decompression has generally been considered to allow right ventricular growth by increasing antegrade blood flow through the tricuspid valve, and to help prevent right ventricular hypertrophy. In patients with myocardial sinusoids, however, sudden decompression may potentially compromise myocardial perfusion because the suprasystemic right ventricle may supply a substantial fraction of myocardial blood flow. In the presence of sinusoidal coronary artery communications, right ventricular decompression could cause a right ventricular steal, ie, runoff from the aorta into the right ventricle during diastole [20] and resultant regional left ventricular dysfunction [21, 22]. In this regard, pulmonary valvotomy is beneficial for the management of a high-pressure right ventricle. We observed, as did others [4, 23], that the right ventricle often remained at either systemic or suprasytemic levels after an initial valvotomy. Thus the second decompression was attempted by a balloon valvotomy or, if not possible, by an operation. Although we have not provided any direct evidence on cardiac performance, we believe a stepwise reduction in right ventricular pressure is a key to successful management of a hypertensive right ventricle with sinusoidal coronary artery communications. An intermediate surgical palliation procedure, ie, the so-called right ventricular overhaul, was indicated when the RVEDV was less than 50% of the predicted normal value. A severely hypoplastic ventricular cavity is usually associated with muscular hypertrophy and decreased ventricular compliance. In such cases, aggressive surgical resection of hypertrophied muscle may be effective to enlarge the volume of the right ventricular cavity. Furthermore, the reduction in the wall thickness may increase its compliance and subsequently improve ventricular function. To encourage forward flow through the tricuspid valve, atrial septal defects were reduced in size, keeping right atrial pressures of less than 15 mm Hg and gradients across the defect of less than 10 mm Hg. If these hemodynamic values could not be achieved during the operation, a right-to-left shunt was controlled with an adjustable snare [24] postoperatively. In most patients, the right atrial pressure gradually dropped over time and the gradient remained between 4 and 8 mm Hg. The efficacy of right ventricular overhaul procedures for the management of very small right ventricles is unclear, because only 2 of the 6 patients have undergone biventricular repair following this procedure. Although Pawade and coworkers [14] preformed biventricular repairs in 5 of 7 patients, their indications for right ventricular overhaul were not reported. Despite the gradual decompression of the right ventricle, the RVEDV increased in all patients undergoing a biventricular repair. Several factors may contribute to the increase in size of the right ventricle, including: (1) regression of the right ventricular hypertrophy after reduction in right ventricular afterload; (2) improving right ventricular compliance; (3) augumenting right ventricular volumes by varying degrees of tricuspid valve regurgitation [4]; (4) reducing right-to-left shunting at the atrial level; and (5) resection of the hypertrophied muscles in the right ventricle. Our results indicate that the initial size of the right ventricle is not really important in the treament strategy, but that a tricuspid valve with the initial diameter of less than 50% of the normal mean or with an initial Z-value of less than 4 may be too hypoplastic to achieve a biventricular repair, even in the presence of a patent infundibulum. In conclusion, the results from our 8-year experience suggest that the multistage palliation procedure makes a definitive biventricular repair of pulmonary atresia or critical pulmonary stenosis with intact ventricular septa possible in the majority of infants with patent infundibula. We believe that myocardial sinusoidal coronary communications can be best treated by gradual decompression of the right ventricle.

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JACOBS (Philadelphia, PA): I noted your conclusion about coronary abnormalities and the recommendation that they be managed by gradual decompression of the right ventricle, but didn t really see in the data a description of the presence of coronary abnormalities. Certainly in the spectrum of this very challenging disease there are some patients who have a right ventricular infundibulum but have marked abnormalities of the coronaries with stenoses or interruption of the native vessels and right ventricular dependence. I wonder if you encountered that and, in that circumstance, if you would still recommend establishment of antegrade flow by pulmonary valvotomy? And then, in addition, you mentioned nine tricuspid valve repairs. I wonder if you could elaborate briefly on that. DR SANO: Thank you for your comment. As I mentioned in the slide, out of 19 patients with pulmonary atresia with intact ventricular septum, we had 8 patients with sinusoidal coronary communication. Only 1 of these seemed to be significant, resulting in right ventricle dependent coronary circulation. The other 7 patients had only a fistula or minor communication, not the interrupted coronary artery. Therefore, we decided to perform a multistage palliation to decompress the right ventricle gradually. During that time we found, in many patients, that sinusoidal coronary communication or coronary fistula disappeared gradually and that it didn t cause much of a problem postoperatively.