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Punch Pulmonary Valvectomy: Another Alternative to Treat Critical Pulmonary Stenosis
HOW TO DO IT
Punch Pulmonary Valvectomy: Another Alternative to Treat Critical Pulmonary Stenosis Simcha Milo, MD, Yaron Bar-El, MD, Zvi Adler, MD, Michael Halberthal, MD, and Abraham Lorber, MD Department of Cardiac Surgery and Units of Pediatric Cardiac Surgery, Pediatric Intensive Care, and Pediatric Cardiology, Rambam Medical Center, Technion-Israel Institute of Technology, Haifa, Israel
For neonates with severe valvar stenosis, or valvar pulmonary atresia with an imperforate pulmonary valve, we present a simple but effective closed procedure using a specially designed valvectomy punch. Seven neonates, who were not suitable for any type of transcatheter procedure, were treated. There were two late deaths,
neither directly related to the operation; 4 patients are developing well. This approach using the valvectomy punch is a fast, safe, and effective procedure.
N
patency. A special operative consent was obtained from both parents after we explained the risks involved in the surgical procedure. Under general anesthesia, we performed a median sternotomy. The pericardium was opened longitudinally and the duct, if needed, dissected free. A small vertical stab was made into the right ventricle using a no. 15 blade and the opening was secured with two square mattress sutures of 5– 0 Prolene (Ethicon, Somerville, NJ) on small pledgets of autologous pericardium. Because of the hypertrophied right ventricular wall, there was no bleeding. To ensure the patency of the infundibulum, slight perpendicular dilation was performed using a mosquito clamp. The punch was then introduced into the right ventricle in closed position (Fig 1, A) and aimed toward the subvalvar area; the procedure was guided by palpation of the external surface of the pulmonary trunk. The screwing mechanism of the punch was then extended toward the pulmonary valve (Fig 1, B). The tip of the screwing mechanism is blunt, rounded, and well polished. The surgeon, therefore, can move easily the tip of the instrument, using his or her left index finger to palpate the pulmonary trunk so as to direct the tip of the instrument into the atretic valve or across the stenotic pathway. The whole punch is then rotated clockwise, while continuing to palpate the pulmonary trunk. In this way the screwing mechanism and the cutting disc can be passed across the valve even when it is stenotic. Subsequent to the device crossing the valve, punching is achieved and the punch is removed from the heart controlling the bleeding by snagging the tourniquets. The removed components of the valvar leaflets can
eonates presenting with extreme pulmonary stenosis or with an imperforate pulmonary valve in the setting of an intact ventricular septum are usually critically ill, irritable, tachypneic, and severely hypoxic from right-to-left shunting at the atrial level. The first successful attempt to relieve valvular pulmonary stenosis using a specially designed instrument, a valvulotome, introduced into the right ventricle through a stab wound incision, was published in 1948 by Brock [1]. The options for treatment of such patients are percutaneous balloon valvotomy [2– 4], closed pulmonary valvotomy [5], laser [6], needle [7] or radiofrequency transcatheter perforation [8], open valvotomy with simple inflow stasis [9], or open valvotomy using cardiopulmonary bypass. Some patients might need an additional transjunctional patch and construction of a systemic-topulmonary arterial shunt. Three types of valvar stenosis can be distinguished: the “dome-shaped” type, the dysplastic, myxomatous, cauliflower type, and the “hourglass” deformity of the pulmonary valve with bottle-shaped sinuses [10]. Whereas percutaneous balloon valvotomy seems to be the treatment of choice for the dome-shaped valve, the other two types, which do not exhibit fusion of commissures between the valve leaflets [10], will arguably benefit more from surgical removal or tailoring of the obstructing leaflets. With this in mind, we have developed a technique whereby most or all of an obstructive or imperforate pulmonary valve can be removed using a punch. Seven patients have now been successfully treated using this punch.
(Ann Thorac Surg 1997;64:261– 4) © 1997 by The Society of Thoracic Surgeons
Technique While awaiting operation, the infants were treated with minimal doses of prostaglandin E1 to maintain ductal Accepted for publication Jan 9, 1997. Address reprint requests to Dr Milo, Department of Cardiac Surgery, Rambam Medical Center, Haifa 31096, Israel.
© 1997 by The Society of Thoracic Surgeons Published by Elsevier Science Inc
This punch was designed by the first author, Simcha Milo, MD, and the prototype was manufactured by Avinoam Livney, MSc. It is patented and manufactured by Scanlan International, One Scanlan Plaza, St. Paul, MN 55107. 0003-4975/97/$17.00 PII S0003-4975(97)00134-3
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HOW TO DO IT MILO ET AL PUNCH PULMONARY VALVECTOMY
Ann Thorac Surg 1997;64:261– 4
Fig 1. (A) Punch in closed position. (B) Punch in open position. (C) Sections of punched out segments of pulmonary valves.
then be retrieved from inside the punch for inspection (Fig 1, C). Repeating the procedure then permits excision of further valvar tissue. When sufficient tissue is deemed to be removed, the procedure is completed by simple ligation of both Prolene sutures around the small ventriculotomy. Blood loss during the procedure was negligible. Over a period of 15 months, only 7 babies were seen at the Rambam Medical Center in Haifa, Israel (Table 1), suffering mainly from critical pulmonary stenosis or pulmonary valve atresia. Repeated attempts to pass a guidewire through the obstructed pulmonic valve failed. They were considered not suitable for percutaneous balloon valvuloplasty and were referred to operation.
Results There was one early death (patient 6) due to steal effect (Fig 2). Blood from the systemic circulation secondary to construction of a Blalock-Taussig shunt coexistent with patent ductus arteriosus caused irreversible systemic acidosis. One late death (patient 1) due to hyperkalemia occurred while the baby was awaiting definitive open heart operation of the right ventricular outflow tract. Neither of the deaths was related directly to the procedure. Patient 4 required a balloon valvoplasty 4 months after the punch valvectomy. Patient 7 is awaiting transjunctional enlargement of his right ventricular outflow tract because of increasing right ventricular failure considered not amenable to balloon valvoplasty. Patient 2 has results
Table 1. All Patients: Demographic, Diagnostic, Therapeutic and Operative Data Patient No. 1
Sex F
Age at Operation 3 days
Preoperative Diagnosis
2
F
2 days
3
M
11 days 8 days
4 5
F F
3 days 1 day
6
F
2 days
7
M
3 days
Severe valvular pulmonary stenosis (quasi atresia) with no antegrade flow Pulmonary steal from the systematic circulation Severe valvular pulmonary stenosis; PDA— large Pulmonary overflow Severe valvular pulmonary stenosis (quasi atresia), dysplasia and stenosis of tricuspid valve Severe valvular pulmonary stenosis Severe valvular pulmonary stenosis, DORV, large perimembranous VSD, ASD Imperforated pulmonary valve with super systemic RV pressure (TR jets 140 mm Hg) Severe pulmonary valve stenosis
1 week
Diaphragmatic hemiparesis, right
7 days
PGE1
Operations
1
Punch pulmonary valvectomy and left modified Blalock-Taussig shunt Ligation of PDA
1
Punch pulmonary valvectomy
1
Ligation of PDA Punch pulmonary valvectomy, 4 mm left modified Blalock-Taussig shunt
1 1 1 1
Punch pulmonary valvectomy Punch pulmonary valvectomy, left modified Blalock-Taussig shunt Punch pulmonary valvectomy, right modified Blalock-Taussig shunt Punch pulmonary valvectomy, 3 mm right modified Blalock-Taussig shunt Plication of diaphragm, right
ASD 5 artrial septal defect; DORV 5 double-outlet right ventricle; PDA 5 patent ductus arteriosus; ventricle; TR 5 tricuspid regurgitation; VSD 5 ventricular septal defect.
PGE1 5 prostaglandin E1;
RV 5 right
Ann Thorac Surg 1997;64:261– 4
HOW TO DO IT MILO ET AL PUNCH PULMONARY VALVECTOMY
263
Fig 2. Anterior view of the residual heavily thickened pulmonary valve after punch valvectomy (patient 6). Note the broad passage for postoperative flow as compared with preoperative condition of an imperforate valve with estimated supersystemic right ventricular pressure of 140 mm Hg.
typical of the successful outcome of the valvectomy procedure (Fig 3). Patients 2, 3, 4, and 5 are asymptomatic and are developing well (Fig 4).
Comment Patients with extreme form of isolated pulmonary stenosis or with an imperforate pulmonary valve pose a challenge to pediatric cardiologists. They are frequently referred for operation, either after failure of percutaneous balloon valvoplasty or because the baby is considered to need an emergency shunt. In this procedure, the subvalvular–infundibular component of the obstruction, should it exist, is not addressed. During the 15-month period of this report, no baby presented having an infundibulum that was a major obstruction by itself. Babies having a thin, imperforated valve with a good size annulus and little or no infundibular obstruction will benefit far more than babies having an extremely thickened dysplastic, cauliflower, or hourglass-type valve, a small annulus, and advanced infundibular stenosis. If the infant does not require a transannular patch, or is too sick to undergo an open heart procedure, closed punch valvectomy, with or without the construction of an aortopulmonary shunt, has an advantage over all other surgical procedures. The results of our procedure can be compared with results from a group of infants aged less than 6 months who underwent closed pulmonary valvotomy [11]. This procedure, judged on the early and midterm findings, resulted in normal right ventricular pressures in
Fig 3. (A) Pressure gradient in the right ventricular outflow tract before punch pulmonary valvectomy is 111 mm Hg. (B) After punch pulmonary valvectomy, the pressure gradient dropped to 24 mm Hg.
some of the patients; some required and will require further balloon valvuloplasties, which are now possible to perform, and some will require patch reconstruction and pulmonary valvectomy at some stage. Yet, the additional procedures, particularly the open heart patch op-
Fig 4. Graphic display of the right ventricular outflow tract pressures (RVOT-P) before and after punch pulmonary valvectomy during a time span of 14 months. (Op 5 operation; P 5 patient.)
264
HOW TO DO IT MILO ET AL PUNCH PULMONARY VALVECTOMY
eration, will carry less morbidity and mortality than if carried out in the neonatal period. All closed procedures including the percutaneous balloon valvuloplasties are blind, yet they seem to work well enough for the pulmonary valve. The resulting pulmonary insufficiency in all babies in this study remained within insignificant limits. This information correlates well with our experience of 20 years of other closed procedures and even open procedures where the complete pulmonary valve (dysplastic or hourglass types) was removed; the amount of pulmonary regurgitation was only mild or mild to moderate and well tolerated over many years, requiring no intervention. A heavily dysplastic valve grows badly and, in only some of patients, gives the illusion of a functioning valve. In our experience, the operative risk for the punch valvectomy is lower than that of an open heart procedure for the mere removal of the pulmonary valve. The procedure is technically simple, fast, and safe. However, there has not yet been any report showing an optimal mode of treatment, and each institution uses the management protocols with which it is most successful [12]. We thank Dr Imad Machul, who morally and medically cared for the babies and their families before operation; Prof Robert H. Anderson, for his constructive remarks; Marcia Ford, for her editorial help; and Barbara McGrath, for her secretarial assistance.
References 1. Brock RC. Pulmonary valvulotomy for the relief of congenital pulmonary stenosis. Report of three cases. Br Med J 1948;I:1121– 6.
Ann Thorac Surg 1997;64:261– 4
2. Lababidi Z, Wu JR. Percutaneous balloon pulmonary valvuloplasty. Am J Cardiol 1983;52:560–2. 3. Pepine CJ, Gessner IH, Feldman RL. Percutaneous balloon valvuloplasty for pulmonic valve stenosis in the adult. Am J Cardiol 1982;50:1442–5. 4. Zeevi B, Keane JF, Fellows KE, Lock JE. Balloon dilatation of critical pulmonary stenosis in the first week of life. J Am Coll Cardiol 1988;11:821– 4. 5. Milo S, Yellin A, Smolinsky A, Blieden LC, Neufeld HN, Goor DA. Closed pulmonary valvotomy in infants under 6 months of age. Report of 14 consecutive cases without mortality. Thorax 1980;35:814– 8. 6. Rosenthal E, Qureshi SA, Kakadekar AP, Anjos R, Baker EJ, Tynan M. Technique of percutaneous laser-assisted valve dilation for valve atresia in congenital heart disease. Br Heart J 1993;69:556– 62. 7. Piechaud JF, Ladeia AM, DaCruz E, et al. Perforationdilatation des atresies pulmonaires a septum interventriculaire intact chez le nouveau-ne´ et le nourrisson. Arch Mal Coeur Vaiss 1993;86:581– 6. 8. Rosenthal E, Qureshi SA, Chan KC, et. al. Radiofrequencyassisted balloon dilatation in patients with pulmonary valve atresia and an intact ventricular septum. Br Heart J 1993;69: 347–51. 9. Jonas RA, Castan˜eda AR, Norwood WI, Freed MD. Pulmonary valvotomy under normothermic caval inflow occlusion. Aust NZ J Surg 1985;55:39– 44. 10. Milo S, Fiegel A, Shem-Tov A, Neufeld HN, Goor DA. Hour-glass deformity of the pulmonary valve. a third type of pulmonary valve stenosis. Br Heart J 1988;60:128–33. 11. Milo S, Mohr R, Goor DA. Right ventricular pressure dynamics after operation for pulmonary stenosis. Ann Thorac Surg 1989;48:572– 4. 12. Hanley FL, Sade RM, Freedom RM, Blackstone EH, Kirklin JW. Outcomes in critically ill neonates with pulmonary stenosis and intact ventricular septum: a multiinstitutional study. Congenital Heart Surgeons Society. J Am Coll Cardiol 1993;22:183–92.
Punch Pulmonary Valvectomy: Another Alternative to Treat Critical Pulmonary Stenosis Simcha Milo, MD, Yaron Bar-El, MD, Zvi Adler, MD, Michael Halberthal, MD, and Abraham Lorber, MD Department of Cardiac Surgery and Units of Pediatric Cardiac Surgery, Pediatric Intensive Care, and Pediatric Cardiology, Rambam Medical Center, Technion-Israel Institute of Technology, Haifa, Israel
For neonates with severe valvar stenosis, or valvar pulmonary atresia with an imperforate pulmonary valve, we present a simple but effective closed procedure using a specially designed valvectomy punch. Seven neonates, who were not suitable for any type of transcatheter procedure, were treated. There were two late deaths,
neither directly related to the operation; 4 patients are developing well. This approach using the valvectomy punch is a fast, safe, and effective procedure.
N
patency. A special operative consent was obtained from both parents after we explained the risks involved in the surgical procedure. Under general anesthesia, we performed a median sternotomy. The pericardium was opened longitudinally and the duct, if needed, dissected free. A small vertical stab was made into the right ventricle using a no. 15 blade and the opening was secured with two square mattress sutures of 5– 0 Prolene (Ethicon, Somerville, NJ) on small pledgets of autologous pericardium. Because of the hypertrophied right ventricular wall, there was no bleeding. To ensure the patency of the infundibulum, slight perpendicular dilation was performed using a mosquito clamp. The punch was then introduced into the right ventricle in closed position (Fig 1, A) and aimed toward the subvalvar area; the procedure was guided by palpation of the external surface of the pulmonary trunk. The screwing mechanism of the punch was then extended toward the pulmonary valve (Fig 1, B). The tip of the screwing mechanism is blunt, rounded, and well polished. The surgeon, therefore, can move easily the tip of the instrument, using his or her left index finger to palpate the pulmonary trunk so as to direct the tip of the instrument into the atretic valve or across the stenotic pathway. The whole punch is then rotated clockwise, while continuing to palpate the pulmonary trunk. In this way the screwing mechanism and the cutting disc can be passed across the valve even when it is stenotic. Subsequent to the device crossing the valve, punching is achieved and the punch is removed from the heart controlling the bleeding by snagging the tourniquets. The removed components of the valvar leaflets can
eonates presenting with extreme pulmonary stenosis or with an imperforate pulmonary valve in the setting of an intact ventricular septum are usually critically ill, irritable, tachypneic, and severely hypoxic from right-to-left shunting at the atrial level. The first successful attempt to relieve valvular pulmonary stenosis using a specially designed instrument, a valvulotome, introduced into the right ventricle through a stab wound incision, was published in 1948 by Brock [1]. The options for treatment of such patients are percutaneous balloon valvotomy [2– 4], closed pulmonary valvotomy [5], laser [6], needle [7] or radiofrequency transcatheter perforation [8], open valvotomy with simple inflow stasis [9], or open valvotomy using cardiopulmonary bypass. Some patients might need an additional transjunctional patch and construction of a systemic-topulmonary arterial shunt. Three types of valvar stenosis can be distinguished: the “dome-shaped” type, the dysplastic, myxomatous, cauliflower type, and the “hourglass” deformity of the pulmonary valve with bottle-shaped sinuses [10]. Whereas percutaneous balloon valvotomy seems to be the treatment of choice for the dome-shaped valve, the other two types, which do not exhibit fusion of commissures between the valve leaflets [10], will arguably benefit more from surgical removal or tailoring of the obstructing leaflets. With this in mind, we have developed a technique whereby most or all of an obstructive or imperforate pulmonary valve can be removed using a punch. Seven patients have now been successfully treated using this punch.
(Ann Thorac Surg 1997;64:261– 4) © 1997 by The Society of Thoracic Surgeons
Technique While awaiting operation, the infants were treated with minimal doses of prostaglandin E1 to maintain ductal Accepted for publication Jan 9, 1997. Address reprint requests to Dr Milo, Department of Cardiac Surgery, Rambam Medical Center, Haifa 31096, Israel.
© 1997 by The Society of Thoracic Surgeons Published by Elsevier Science Inc
This punch was designed by the first author, Simcha Milo, MD, and the prototype was manufactured by Avinoam Livney, MSc. It is patented and manufactured by Scanlan International, One Scanlan Plaza, St. Paul, MN 55107. 0003-4975/97/$17.00 PII S0003-4975(97)00134-3
262
HOW TO DO IT MILO ET AL PUNCH PULMONARY VALVECTOMY
Ann Thorac Surg 1997;64:261– 4
Fig 1. (A) Punch in closed position. (B) Punch in open position. (C) Sections of punched out segments of pulmonary valves.
then be retrieved from inside the punch for inspection (Fig 1, C). Repeating the procedure then permits excision of further valvar tissue. When sufficient tissue is deemed to be removed, the procedure is completed by simple ligation of both Prolene sutures around the small ventriculotomy. Blood loss during the procedure was negligible. Over a period of 15 months, only 7 babies were seen at the Rambam Medical Center in Haifa, Israel (Table 1), suffering mainly from critical pulmonary stenosis or pulmonary valve atresia. Repeated attempts to pass a guidewire through the obstructed pulmonic valve failed. They were considered not suitable for percutaneous balloon valvuloplasty and were referred to operation.
Results There was one early death (patient 6) due to steal effect (Fig 2). Blood from the systemic circulation secondary to construction of a Blalock-Taussig shunt coexistent with patent ductus arteriosus caused irreversible systemic acidosis. One late death (patient 1) due to hyperkalemia occurred while the baby was awaiting definitive open heart operation of the right ventricular outflow tract. Neither of the deaths was related directly to the procedure. Patient 4 required a balloon valvoplasty 4 months after the punch valvectomy. Patient 7 is awaiting transjunctional enlargement of his right ventricular outflow tract because of increasing right ventricular failure considered not amenable to balloon valvoplasty. Patient 2 has results
Table 1. All Patients: Demographic, Diagnostic, Therapeutic and Operative Data Patient No. 1
Sex F
Age at Operation 3 days
Preoperative Diagnosis
2
F
2 days
3
M
11 days 8 days
4 5
F F
3 days 1 day
6
F
2 days
7
M
3 days
Severe valvular pulmonary stenosis (quasi atresia) with no antegrade flow Pulmonary steal from the systematic circulation Severe valvular pulmonary stenosis; PDA— large Pulmonary overflow Severe valvular pulmonary stenosis (quasi atresia), dysplasia and stenosis of tricuspid valve Severe valvular pulmonary stenosis Severe valvular pulmonary stenosis, DORV, large perimembranous VSD, ASD Imperforated pulmonary valve with super systemic RV pressure (TR jets 140 mm Hg) Severe pulmonary valve stenosis
1 week
Diaphragmatic hemiparesis, right
7 days
PGE1
Operations
1
Punch pulmonary valvectomy and left modified Blalock-Taussig shunt Ligation of PDA
1
Punch pulmonary valvectomy
1
Ligation of PDA Punch pulmonary valvectomy, 4 mm left modified Blalock-Taussig shunt
1 1 1 1
Punch pulmonary valvectomy Punch pulmonary valvectomy, left modified Blalock-Taussig shunt Punch pulmonary valvectomy, right modified Blalock-Taussig shunt Punch pulmonary valvectomy, 3 mm right modified Blalock-Taussig shunt Plication of diaphragm, right
ASD 5 artrial septal defect; DORV 5 double-outlet right ventricle; PDA 5 patent ductus arteriosus; ventricle; TR 5 tricuspid regurgitation; VSD 5 ventricular septal defect.
PGE1 5 prostaglandin E1;
RV 5 right
Ann Thorac Surg 1997;64:261– 4
HOW TO DO IT MILO ET AL PUNCH PULMONARY VALVECTOMY
263
Fig 2. Anterior view of the residual heavily thickened pulmonary valve after punch valvectomy (patient 6). Note the broad passage for postoperative flow as compared with preoperative condition of an imperforate valve with estimated supersystemic right ventricular pressure of 140 mm Hg.
typical of the successful outcome of the valvectomy procedure (Fig 3). Patients 2, 3, 4, and 5 are asymptomatic and are developing well (Fig 4).
Comment Patients with extreme form of isolated pulmonary stenosis or with an imperforate pulmonary valve pose a challenge to pediatric cardiologists. They are frequently referred for operation, either after failure of percutaneous balloon valvoplasty or because the baby is considered to need an emergency shunt. In this procedure, the subvalvular–infundibular component of the obstruction, should it exist, is not addressed. During the 15-month period of this report, no baby presented having an infundibulum that was a major obstruction by itself. Babies having a thin, imperforated valve with a good size annulus and little or no infundibular obstruction will benefit far more than babies having an extremely thickened dysplastic, cauliflower, or hourglass-type valve, a small annulus, and advanced infundibular stenosis. If the infant does not require a transannular patch, or is too sick to undergo an open heart procedure, closed punch valvectomy, with or without the construction of an aortopulmonary shunt, has an advantage over all other surgical procedures. The results of our procedure can be compared with results from a group of infants aged less than 6 months who underwent closed pulmonary valvotomy [11]. This procedure, judged on the early and midterm findings, resulted in normal right ventricular pressures in
Fig 3. (A) Pressure gradient in the right ventricular outflow tract before punch pulmonary valvectomy is 111 mm Hg. (B) After punch pulmonary valvectomy, the pressure gradient dropped to 24 mm Hg.
some of the patients; some required and will require further balloon valvuloplasties, which are now possible to perform, and some will require patch reconstruction and pulmonary valvectomy at some stage. Yet, the additional procedures, particularly the open heart patch op-
Fig 4. Graphic display of the right ventricular outflow tract pressures (RVOT-P) before and after punch pulmonary valvectomy during a time span of 14 months. (Op 5 operation; P 5 patient.)
264
HOW TO DO IT MILO ET AL PUNCH PULMONARY VALVECTOMY
eration, will carry less morbidity and mortality than if carried out in the neonatal period. All closed procedures including the percutaneous balloon valvuloplasties are blind, yet they seem to work well enough for the pulmonary valve. The resulting pulmonary insufficiency in all babies in this study remained within insignificant limits. This information correlates well with our experience of 20 years of other closed procedures and even open procedures where the complete pulmonary valve (dysplastic or hourglass types) was removed; the amount of pulmonary regurgitation was only mild or mild to moderate and well tolerated over many years, requiring no intervention. A heavily dysplastic valve grows badly and, in only some of patients, gives the illusion of a functioning valve. In our experience, the operative risk for the punch valvectomy is lower than that of an open heart procedure for the mere removal of the pulmonary valve. The procedure is technically simple, fast, and safe. However, there has not yet been any report showing an optimal mode of treatment, and each institution uses the management protocols with which it is most successful [12]. We thank Dr Imad Machul, who morally and medically cared for the babies and their families before operation; Prof Robert H. Anderson, for his constructive remarks; Marcia Ford, for her editorial help; and Barbara McGrath, for her secretarial assistance.
References 1. Brock RC. Pulmonary valvulotomy for the relief of congenital pulmonary stenosis. Report of three cases. Br Med J 1948;I:1121– 6.
Ann Thorac Surg 1997;64:261– 4
2. Lababidi Z, Wu JR. Percutaneous balloon pulmonary valvuloplasty. Am J Cardiol 1983;52:560–2. 3. Pepine CJ, Gessner IH, Feldman RL. Percutaneous balloon valvuloplasty for pulmonic valve stenosis in the adult. Am J Cardiol 1982;50:1442–5. 4. Zeevi B, Keane JF, Fellows KE, Lock JE. Balloon dilatation of critical pulmonary stenosis in the first week of life. J Am Coll Cardiol 1988;11:821– 4. 5. Milo S, Yellin A, Smolinsky A, Blieden LC, Neufeld HN, Goor DA. Closed pulmonary valvotomy in infants under 6 months of age. Report of 14 consecutive cases without mortality. Thorax 1980;35:814– 8. 6. Rosenthal E, Qureshi SA, Kakadekar AP, Anjos R, Baker EJ, Tynan M. Technique of percutaneous laser-assisted valve dilation for valve atresia in congenital heart disease. Br Heart J 1993;69:556– 62. 7. Piechaud JF, Ladeia AM, DaCruz E, et al. Perforationdilatation des atresies pulmonaires a septum interventriculaire intact chez le nouveau-ne´ et le nourrisson. Arch Mal Coeur Vaiss 1993;86:581– 6. 8. Rosenthal E, Qureshi SA, Chan KC, et. al. Radiofrequencyassisted balloon dilatation in patients with pulmonary valve atresia and an intact ventricular septum. Br Heart J 1993;69: 347–51. 9. Jonas RA, Castan˜eda AR, Norwood WI, Freed MD. Pulmonary valvotomy under normothermic caval inflow occlusion. Aust NZ J Surg 1985;55:39– 44. 10. Milo S, Fiegel A, Shem-Tov A, Neufeld HN, Goor DA. Hour-glass deformity of the pulmonary valve. a third type of pulmonary valve stenosis. Br Heart J 1988;60:128–33. 11. Milo S, Mohr R, Goor DA. Right ventricular pressure dynamics after operation for pulmonary stenosis. Ann Thorac Surg 1989;48:572– 4. 12. Hanley FL, Sade RM, Freedom RM, Blackstone EH, Kirklin JW. Outcomes in critically ill neonates with pulmonary stenosis and intact ventricular septum: a multiinstitutional study. Congenital Heart Surgeons Society. J Am Coll Cardiol 1993;22:183–92.