OBJECTIVE: To summarize our department’s experience in surgical treatment of neonates and infants with intact ventricular septum pulmonary atresia and critical pulmonary valve stenosis from April 1997 to August 2007. METHODS: Surgical treatment was performed in 23 cases, aged 6d~11 months. Among them, there were 10 cases of ventricular septal intact pulmonary atresia and 13 cases of critical pulmonary valve stenosis. 19 cases were operated via a median chest incision under extracorporeal circulation without stopping the heart, and 4 cases were operated by a non-corporeal circulation method using a left posterior posterolateral chest incision. Except for one case of early simultaneous action of pulsatile ductus arteriosus (PDA) ligation and patent foramen ovale (PFO) suture, the remaining 22 cases were performed by preserving PDA and incising the pulmonary valve alone. RESULTS: There were 2 perioperative deaths, which were due to hypoxemia and acute renal failure, respectively. Echocardiographic measurements of pulmonary transvalvular pressure difference on the day of surgery ranged from 37 to 132 mmHg (1 mmHg = 0.133 kpa), with an average of 61 mmHg. 2-week follow-up showed that pulmonary transvalvular pressure difference ranged from 26 to 77 mmHg, with an average of 43 mmHg, which was significantly lower than that in the early postoperative period (P<0.05). Arterial oxygen saturation measured without oxygen before discharge ranged from 78% to 92%, with a mean of 85%, which was significantly higher than that before surgery (P<0.05). Follow-up was from 4 months to 10 years, with a mean of 5.8 years. all PDAs were closed, pulmonary artery blood flow was smooth, and tricuspid regurgitation disappeared or was significantly reduced. CONCLUSION: Preservation of the arterial conduit and simple pulmonary valvotomy is a safe and effective method for the treatment of membranous atresia of the pulmonary artery with intact ventricular septum and critical pulmonary stenosis in newborns and infants. Zhang Hui, Department of Cardiac Surgery, Capital Institute of Pediatrics Critical pulmonary stenosis refers to extremely severe stenosis of the pulmonary valve close to atresia, whose pathological anatomy and pathophysiological characteristics are very similar to those of ventricular septal intact pulmonary arterial membranous atresia, and is often combined with right ventricular dysplasia, whose survival is dependent on the opening of arterial conduits. Currently, the surgical treatment of this type of malformation is not standardized. We have treated these malformations in 23 newborns and infants for 10 consecutive years by simply incising the pulmonary valve, preserving the arterial conduit and horizontal atrial traffic, and not dealing with tricuspid valve closure insufficiency, with satisfactory results. DATA AND METHODS: From April 1997 to August 2007, 23 cases of children were treated surgically. Age ranged from 6 days to 11 months, with an average of 3.2 months. Including 7 cases of neonates and 16 cases of infants. All cases were diagnosed by preoperative echocardiography, with weights ranging from 2.8 to 9.0 kg, with an average of 4.8 kg. There were 10 cases of pulmonary atresia with intact ventricular septum and 13 cases of critical pulmonary stenosis. 22 children had combined arterial ductus arteriosus (PDA) with a diameter of the ductus arteriosus ranging from 1.5 to 4 mm, and all of them had patent foramen ovale (PFO) or small atrial septal defects (ASD), with a right-to-left shunt at the atrial level. The tricuspid valve was moderately to severely incompetent, and the right atrium was markedly enlarged. 2 cases had severe right ventricular dysplasia, with right ventricular volume indices of 5 mL/m2 and 12 mL/m2, respectively. all children had right ventricular funneling and no right ventricle-dependent coronary circulation. The electrocardiogram showed right ventricular hypertrophy, with T-wave changes in two cases. Preoperative arterial oxygen saturation ranged from 49% to 81%, with a mean of 63%. 15 children were operated as emergencies and 8 as elective surgeries. 19 cases were operated without cardiac interruption under extracorporeal circulation via a median thoracic incision, and 4 cases were operated with non-extracorporeal circulation through a left posterior posterolateral thoracic incision. 22 cases opted for a pulmonary artery incision, and 1 case was operated early via a right ventricular outflow tract incision. RESULTS: There were 2 perioperative deaths, both of which were neonates. 1 case died of intractable hypoxemia after early incision of the pulmonary valve via the right ventricular outflow tract, and the other case died of acute renal failure. Two of the 21 survivors had postoperative low cardiac output syndrome and pulmonary infection, secondary intubation, and one had cardiac arrest. Both of these children with severe right ventricular dysplasia had frequent episodes of right ventricular outflow tract spasm in the early postoperative period, which improved with intravenous esmolol and oral cardiac glycosides, and they were eventually discharged from the hospital. Echocardiographic measurements on the day of surgery showed that the pulmonary transvalvular pressure difference ranged from 37 to 132 mmHg (1 mmHg=0.133 kpa), with an average of 61 mmHg. 2 weeks later, the pulmonary transvalvular pressure difference ranged from 26 to 77 mmHg, with an average of 43 mmHg, which was significantly lower than that in the early postoperative period (P<0.05). Arterial oxygen saturation measured without oxygen before discharge ranged from 78% to 92%, with a mean of 85%, which was significantly higher than that before surgery (P<0.05). The follow-up period ranged from 4 months to 10 years, with a mean of 5.8 years, with good general condition and a significant increase in activity endurance. In 10 cases, the right ventricle returned to normal size, the atrial level was a left-to-right shunt, tricuspid regurgitation disappeared, and there was no residual pulmonary stenosis or pulmonary regurgitation. 5 cases had normal right ventricular diameter, but the atrial level was a bi-directional shunt with a predominantly left-to-right shunt, tricuspid regurgitation was reduced or disappeared, and cyanosis disappeared in the resting state. In the remaining 6 cases, the atrial level was still a bidirectional shunt, but the tricuspid regurgitation was reduced to mild, and the right ventricle was significantly enlarged compared with the preoperative level. DISCUSSION: The common feature of critical pulmonary stenosis and septally intact pulmonary membranous atresia is the lack of antegrade flow from the right ventricle to the pulmonary artery, and pulmonary arterial blood flow can only originate from the arterial conduit or collateral circulation. Obstruction of the right ventricular outlet results in hypertrophy of the right ventricular wall, small right ventricular cavity, and in some cases combined with right ventricular dysplasia. Children usually have severe tricuspid regurgitation with extreme enlargement and hypertrophy of the right atrium. The foramen ovale is open and there is right-to-left shunting at the atrial level. These children are born highly hypoxic and depend on the ductus arteriosus for survival. Once the ductus arteriosus closes or tends to close, due to the underdevelopment of the body-pulmonary collateral circulation and the inability to quickly and adequately establish an effective collateral circulation, severe hypoxia and progressive acidosis will soon occur, which will eventually lead to death. Therefore, once diagnosed, surgery should be performed as soon as possible, which is usually an emergency surgery. Preoperatively, continuous intravenous prostaglandin E1 (PGE1) is required to keep the ductus arteriosus open, and at the same time, acidosis should be corrected aggressively, avoiding inhalation of high oxygen concentration. The diagnosis is usually made by echocardiography, but special attention should be paid to the right ventricular outflow tract. Our experience is that if there is a mass of muscle protruding into the right ventricular outflow tract under the pulmonary valve, postoperative hypoxemia is often a complication. This is because preoperatively, due to right ventricular outlet obstruction, the right ventricular cavity pressure is extremely elevated and the right ventricular outflow tract is relatively dilated, making the right ventricular outflow tract appear large enough. Once the right ventricular obstruction is lifted, the right ventricular cavity pressure rapidly decreases and the masseter muscle opposes each other, which will inevitably result in a new obstruction, especially if outflow tract spasm occurs after some stimulus. Two of our children developed intractable hypoxemia due to frequent episodes of right ventricular outflow tract spasm in the early postoperative period, which increased the risk of surgery. In addition, the presence of right ventricle-dependent coronary circulation needs to be clarified, so right ventricular decompression surgery cannot be performed in these children. The main surgical approaches currently used include pulmonary valvotomy, right ventricular outflow tract patching, and body-pulmonary bypass alone or in combination with these approaches. The aim is to provide definitive pulmonary blood flow to improve arterial oxygen saturation in the body circulation through a one-stage procedure, and to establish an antegrade flow through the right ventricle to promote right ventricular and tricuspid valve development as much as possible, and ultimately to perform biventricular repair as much as possible [1]. Our current surgical protocol is to preserve the horizontal atrial traffic and the ductus arteriosus, not to deal with tricuspid valve insufficiency, and to simply incise the pulmonary valve. The surgery can be accomplished either with a mid-thoracic incision without cardiac non-stopping under extracorporeal circulation or via a left posterior posterolateral thoracic incision without extracorporeal circulation. Since the ductus arteriosus is the only channel to protect the child's life until effective forward blood flow is established, special care should be taken to avoid spasm or even closure of the ductus arteriosus due to irritation, which may lead to severe hypoxia, acidosis, or even fatal arrhythmia or cardiac arrest. In one case, the risk of surgery was increased by two episodes of ventricular fibrillation and hypotension due to the stimulation of the operation. In addition, the pulmonary artery incision was made transversely, usually 5-10 mm above the pulmonary valve annulus, and a longitudinal incision was avoided because it was possible to tear the main pulmonary artery incision to the pulmonary valve annulus when dilating the valve with vascular forceps after incising the pulmonary valve, which could lead to stenosis of the pulmonary valve annulus when closing the incision, thus compromising the outcome of the operation. We did not contemporaneously treat the other combined malformations because, although the pulmonary valve was incised as widely as possible during surgery, it was difficult to achieve "ideal" blood flow in the anterior pulmonary artery in the early postoperative period because of edema of the pulmonary valve tissues and the influence of hypertrophied muscle bundles in the right ventricular outflow tract, which would have resulted in perioperative hypoxemia had the arterial conduit been closed, and therefore, it was important to keep the arterial conduit open in the early postoperative period. Therefore, keeping the ductus arteriosus open is beneficial for early postoperative recovery and ensures a certain level of oxygen saturation. In addition, these children may have a small right ventricular volume, hypertrophy of the right ventricular wall, and reduced compliance of the ventricular wall, resulting in high right ventricular pressures in the early postoperative period. Preservation of the patent foramen ovale or atrial septal defect can provide right heart decompression, otherwise it is very likely to lead to severe right heart failure. With the disappearance of tissue edema and improvement of ventricular wall compliance, right ventricular pressure and pulmonary transvalvular pressure difference usually decrease significantly 1 to 2 weeks after surgery, and tricuspid regurgitation and right-to-left shunting at the level of the atria are significantly reduced. We do not routinely add a body-pulmonary shunt along with pulmonary valvotomy because determining when the right ventricle can independently support the pulmonary circulation without such a shunt is difficult and impossible. Once there is sufficient forward blood flow through the right ventricle, common pulmonary blood flow from the right ventricle and shunt may result in volume overload and, in some children, left heart failure. In contrast, the arterial catheter can close naturally with postoperative oxygen saturation, and its natural regulation is significantly superior to a fixed body-pulmonary shunt. Kirklin and Barrat-Boyes estimated that with a z value of -1, 48% of children would no longer need a shunt 1 month after pulmonary valvotomy, and with a z value of -2, 34% of children would not need a shunt. Similarly, Ovaert found that 33% of children were no longer dependent on the PDA 1 month after balloon dilatation of the pulmonary valve, and our follow-up results also showed that the PDA closed on its own in all children whose echocardiograms were reviewed within 3 months after pulmonary valvotomy. In addition, we did not apply a body-pulmonary shunt because of its tendency to cause distortion of the pulmonary artery, which reduces surgical outcome and increases the likelihood of reoperation. However, in children with secondary hypertrophic muscle bundles projecting into the right ventricular outflow cavity or pulmonary annular dysplasia, a body-pulmonary shunt should be performed concomitantly with a pulmonary valvotomy. Furthermore, we do not use transannular patching of the outflow tract because this approach can exacerbate myocardial injury, exacerbate myocardial edema, decrease cardiac compliance, and predispose to postoperative low cardiac output syndrome. Furthermore, transannular patching can also lead to pulmonary regurgitation, increasing right ventricular load and the likelihood of reoperation. In contrast, pulmonary valvotomy is superior to outflow tract patching because it reduces right ventricular injury and protects more of the pulmonary valve due to minimal pulmonary regurgitation. In addition, this procedure can be performed without extracorporeal circulation. Despite the fact that some children have combined right ventricular dysplasia, we use pulmonary valvulotomy alone to treat critical pulmonary stenosis and septally intact pulmonary atresia. This is because the potential for right ventricular growth after pulmonary valvulotomy is largely unknown, and even severely hypoplastic right ventricles may grow. Several factors can contribute to right ventricular growth after right ventricular decompression: 1, reduced right ventricular afterload can contribute to degenerative right ventricular hypertrophy; 2, altered right ventricular compliance; 3, altered tricuspid regurgitation can increase right ventricular volume; and 4, reduced right-to-left shunting at the atrial level. It can be seen that, although some children are ultimately left with the option of single-ventricle repair, early pulmonary valvotomy not only effectively improves arterial oxygen saturation in the circulation but also provides an opportunity for right ventricular development. Some of these children may be able to achieve anatomic cure without additional surgery in the future. ovaert's 5-year follow-up of children with balloon dilatation of the pulmonary valve found that 55% had biventricular circulation, although the tricuspid valve diameter or z-value may have been slightly smaller than normal. in Ashburn's bulk report of 408 children, 85% ultimately underwent radical surgery, with 50% of these children undergoing surgery. In Ashburn's bulk report of 408 children, 85% of the children ultimately underwent radical surgery, with 50% of them having biventricular repair. In contrast, Sano reported that biventricular repair was ultimately performed in 90% of children. Postoperative maintenance of patent ductus arteriosus (PGE1) at low doses to increase pulmonary blood flow facilitates the smooth transition through the early perioperative period. Usually, PGE1 is used until 3 to 5 days after surgery, and the dose is gradually reduced. When it is difficult to withdraw PGE1, β-blockers are added. In addition, for children with obvious secondary hypertrophic muscle bundles projecting into the right ventricular outflow tract, postoperative spasm of the right ventricular outflow tract is often triggered by certain factors, resulting in hypoxemia, which requires special vigilance. In these children, beta-blockers can be used with good results. These are usually small doses of esmolol (1-5 μg-1kg-1min) or oral cardioplegia (1 mg-1kg-1d-1). In addition, β-agonists such as isoproterenol should be avoided in the postoperative period, and placement of a temporary pacing lead is advocated for raising the heart rate when necessary. In conclusion, simple incision of the pulmonary valve with preservation of the arterial conduit and horizontal atrial traffic is a safe and effective method for the treatment of critical pulmonary stenosis and septally intact membranous atresia of the pulmonary arteries in neonates and infants. With advances in medical technology, the preferred treatment option for these children in the future should be interventional therapy.