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Ann Thorac Surg 2000;70:1501-1506
© 2000 The Society of Thoracic Surgeons
a Department of Cardiovascular Surgery, Okayama University Medical School, Okayama, Japan
b Pediatrics, Okayama University Medical School, Okayama, Japan
Addres reprint requests to Dr Sano, Department of Cardiovascular Surgery, Okayama University Medical School, 2-5-1 Shikata-cho, Okayama-City 700-8558, Japan
e-mail: s-sano{at}cc.okayama-u.ac.jp
Presented at the Thirty-sixth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL Jan 31Feb 2, 2000.
| Abstract |
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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 enddiastolic 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.
| Introduction |
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Several studies [47] 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 systemicpulmonary ar tery 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 sinusoidalcoronary artery communication.
| Patients and methods |
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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 sinusoidalcoronary artery communications were identified in 8 pulmonary atresia patients. One of these seemed to be significant, ie, resulting in right ventricledependent 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 Simpsons rule as previously described [8]. Right ventricular enddiastolic 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].
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Initial surgical palliation
All patients underwent a transarterial pulmonary valvotomy and a systemicpulmonary 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 ventricular failure and subsequently underwent a bidirectional Glenn anstomosis on postoperative day 9.
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| Results |
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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 systemicpulmonary 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).
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| Comment |
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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 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 ventricularpulmonary 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 systemicpulmonary 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 sinusoidalcoronary 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 sinusoidalcoronary 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 sinusoidalcoronary communications can be best treated by gradual decompression of the right ventricle.
| Footnotes |
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| References |
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