What is the pathological anatomy and surgical treatment of sickle syndrome? Sickle syndrome is a form of partial pulmonary venous ectopic drainage with an incidence of 2/100,000 in the population and accounts for approximately 3-6% of all partial pulmonary venous ectopic drainage. But it is far from a simple partial pulmonary venous ectopic drainage. It is a complex malformation of the heart and lungs. Therefore, the surgical correction of sickle syndrome needs to be based on a thorough understanding of its pathologic and anatomic structure. The history of this complex malformation of ectopic pulmonary venous drainage was first reported by Cooper and Chasinat in 1836, and the term “sickle” was first applied in 1956 and described as a “sickle-like” venous drainage into the inferior vena cava. The concept of “sickle syndrome” was first applied by Neill in 1960. The anatomy of sickle syndrome is diverse and includes the following aspects: 1. Ectopic pulmonary venous drainage: It can be all right pulmonary veins, or it can be the right inferior pulmonary vein and the right middle pulmonary vein draining cephalad to caudal in the direction of the septum in a crescent shape, above or below the junction of the inferior vena cava and the right atrium into the corpora venereal system. Alternatively, the bilateral inferior pulmonary veins may form a common trunk draining downward into the inferior vena cava. All of the right pulmonary veins into the corporal veins are more common in infants and children. The anomalous draining pulmonary vein is usually anterior to the right pulmonary hilar. When the anomalous pulmonary vein enters the inferior cavity, it is usually directly above the hepatic vein into the inferior vena cava. In rare cases, the abnormally draining pulmonary vein bypasses the inferior vena cava and enters the left atrium, creating a normal pulmonary venous drainage. This may also manifest as the right inferior pulmonary vein and the right middle pulmonary vein draining into the inferior vena cava, with the rest of the right pulmonary vein merging into a branch that drains into the odd vein, which enters the superior vena cava. The abnormally draining pulmonary vein may manifest as a stenosis at the entrance site when it enters the body vein. This is an important cause of post-surgical pulmonary vein stenosis. Traffic can exist between the abnormally draining pulmonary veins and the normal pulmonary veins. 2, Other pulmonary vein anomalies: abnormal drainage of the left pulmonary vein into the right atrium and narrowing of the left common pulmonary vein opening. 3.Anomalous development of right pulmonary artery: It can be manifested as mild to severe dysplasia of right pulmonary artery. It can also manifest as abnormal right pulmonary artery branching, which can be localized with reduced branching, abnormal distribution of pulmonary segments, or no pulmonary artery distribution in localized areas. 4. Somatic pulmonary collateral formation: The right lower lung is supplied by collateral vessels originating from the descending aorta or abdominal aorta, and there may be no pulmonary artery branches supplying blood in this region. Since the lung tissue is still supplied by the bronchial arteries, blocking the abnormal somatic pulmonary collateral branches will not cause necrosis of the lung tissue. Sometimes, the diameter of these collateral vessels can reach up to 40% of the diameter of the aorta at the site of origin. These somatic pulmonary collateral vessels may have accompanying veins that drain blood from these somatic pulmonary collateral vessels to the inferior vena cava. 5.Inferior vena cava anomaly: It is manifested as atresia of the inferior vena cava and narrowing of the inferior vena cava. In this case, the inferior vena cava drains to the superior vena cava via the odd vein. The hepatic vein goes directly into the right atrium. 6.Various cardiac anomalies: Among the anomalies that will affect the outcome of surgery are left ventricular dysplasia, subaortic stenosis, and left common pulmonary vein stenosis. These malformations seriously affect the function of the left heart and are the main cause of postoperative death. 7, abnormal heart position: manifested as right displacement of the heart. 8, Pulmonary malformations: manifested as horseshoe lung, right lower lung isolation.9 Combined malformations: sickle syndrome rarely manifests as a single malformation of the heart. Comorbid malformations, in descending order of prevalence, are: right lung hypoplasia; right heart displacement; right pulmonary artery hypoplasia; right lower lung supplied by collateral vessels originating from the descending aorta below the diaphragm; secondary foramen ovale septal defect; and diaphragmatic hernia. Most patients have mediastinal displacement and rightward displacement of the heart due to right lung hypoplasia, and in severe cases the entire heart is located in the right thoracic cavity. Clinical manifestations Depending on the amount of fractional flow, the patient’s symptoms can manifest as panic, shortness of breath, limited activity, congestive heart failure, etc. Dupuis et al. divided the syndrome into infantile and adult forms. The former type has severe clinical symptoms, abnormal body pulmonary lateral branch coarsening, left-to-right shunt flow >50%, and severely elevated pulmonary artery pressure, mostly manifesting as congestive heart failure, while lacking typical chest X-ray features, with poor natural prognosis. The latter resembles a small ASD with normal or mildly elevated pulmonary artery pressure. They may present with recurrent pneumonia or upper respiratory tract infections or be asymptomatic, mostly with typical chest radiographs. Exceptions may be made in cases of combined intracardiac malformations. Causes of pulmonary hypertension include: left-to-right shunts from the pulmonary veins to the inferior vena cava; sickle vein stenosis; combined intracardiac malformations; reduced pulmonary vascular bed due to pulmonary dysplasia; and coarse body pulmonary collateral. In some patients, pulmonary hypertension persists after correction of ectopic pulmonary venous drainage. Diagnosis The pathology of sickle syndrome is based on partial drainage of the right pulmonary vein into the inferior vena cava, either to the junction of the inferior vena cava and the right atrium or to the right atrium. The literature reports ectopic drainage of the entire right pulmonary vein in two-thirds of patients and ectopic drainage of the right inferior pulmonary vein only in one-third of patients. The goal of diagnosis is to identify the ectopic pulmonary vein and the site of drainage preoperatively. The common diagnostic tools are transthoracic ultrasound, cardiac catheterization, CT, and MRI, but ultrasound diagnosis is difficult because the ectopic draining pulmonary veins are sometimes far from the heart. In this case, cardiac catheterization and angiography are needed. It can clarify: 1) the diagnosis of sickle syndrome; 2) the course of the ectopically draining pulmonary veins; 3) the presence or absence of stenosis of the ectopically draining pulmonary veins; 4) the distribution of the pulmonary arteries and the pressure of the pulmonary arteries; 5) the left-to-right shunt flow; 6) the combined intracardiac malformations; 7) the body-pulmonary collateral condition of the right lung. Cardiac catheterization and angiography are the gold standard for the diagnosis of sickle syndrome. Considering the non-invasive examination, multi-row CT angiography has become the diagnostic method of choice for sickle syndrome. It can clarify both the pulmonary vascularity, including the condition of the somatic pulmonary collateral, and the pulmonary parenchyma. Indications for surgery Sickle syndrome combined with ASD, combined with pulmonary hypertension, combined with ectopic drainage of pulmonary venous trunk stenosis require prompt surgery. Patients with Qp:Qs greater than 1.5:1 should be operated promptly, regardless of the presence of symptoms. In infants without pulmonary hypertension, follow-up can be performed first. It has also been suggested that surgery can be performed in infancy if it can be done non-in vitro after evaluation. The aims of surgery include (1) embolization or ligation of the anomalous corpora arteriosa and resection of the isolated lung, (2) diversion of SV into the left atrium, and (3) correction of combined intracardiac malformations. Surgical approach The first treatment of sickle syndrome was performed by Drake et al. in 1950. The method they used was right lower pneumonectomy. Pneumonectomy is certainly not currently recommended for the treatment of sickle syndrome. However, pneumonectomy may still be considered in patients with recurrent pulmonary infections, persistent coughing of blood, recurrent thrombosis of the intra-atrial patch, or significant right lung dysplasia. Ligation of ectopic draining pulmonary veins alone can cause pulmonary congestion or pulmonary infarction. physiological correction of sickle syndrome was first performed by Kirklin in 1956. The ectopic draining pulmonary vein trunk was first anastomosed to the right atrium, and then the anastomosed pulmonary vein was septated into the left atrium by repairing the ASD. 1961 Tornall first anastomosed the ectopic draining pulmonary vein directly into the left atrium. The choice of surgical route for sickle syndrome depends on the combined intracardiac malformation and can be made with either a median sternotomy or a right-sided incision. Intraoperative care is always needed to prevent stenosis of the ectopic draining pulmonary vein opening. The management of the somatic pulmonary collateral branches (surgical ligation or intraoperative closure) is very important to prevent the continuation of postoperative pulmonary hypertension and the failure of cardiac function. The choice of surgical approach in sickle syndrome depends on the structure of its pathological anatomy. The surgical approach should vary according to the anatomic-pathological presentation of each patient. There are four main surgical approaches: 1 Intra-atrial access technique: i.e., through the atrial septal defect, an intra-atrial access is constructed in the right atrium and the sickle vein is drained from its entrance in the inferior vena cava to the left atrium; whether the DHCA technique is used or not is determined mainly by the location of the SV entrance. If its opening is below the level of the diaphragm, DHCA is mostly used. with DHCA, the inferior vena cava does not need to be cannulated and the opening of the ectopic draining pulmonary vein and the opening of the hepatic vein can be better revealed.2 The direct anastomosis technique, in which the SV is directly cut from the inferior vena cava and anastomosed directly to the posterior wall of the left atrium, is used. This approach can also be done with a right-sided incision and non-extracorporeal circulation if there is no combined intracardiac malformation or if the combined ASD is suitable for occlusion. A direct SV anastomosis followed by ultrasound-guided transthoracic ASD occlusion is performed.3 The intraatrial access technique is combined with the direct anastomosis technique, in which the SV is cut directly from the inferior vena cava and then anastomosed to the lateral wall of the right atrium before being septated into the left atrium during repair of the septal defect. The first method is suitable for older patients and has the following disadvantages: A it does not resolve the SV itself or its stenosis at the entrance of the inferior vena cava; B there is a distant contracture of the intra-atrial channel; and there is an 1800 turn in the CSV blood return pathway. Patients with infantile type tend to have combined SV stenosis. It has been reported that 100% of patients with infantile type have SV reflux obstruction after the application of intra-atrial access technique, and patients mostly require reoperation, while those with direct anastomosis technique are less likely to have it. Therefore, a second approach is recommended for infantile patients.4 The modified intraatrial access technique involves transecting the inferior vena cava at the entrance of the inferior vena cava, cutting the septum and the posterior wall of the left atrium attached to it downward at the fossa ovalis, reconstructing the connection between the posterior wall of the left atrium and the posterior wall of the inferior vena cava, reconstructing the septum with an autologous pericardial slice, and septating the SV into the left atrium. This solved the problem of distant stenosis of the intraatrial access and made it possible to apply it to infants and children. Hospital materials 1. Clinical data: 1 case of SS from January 1997 to December 2012, 13 males and 9 females; age 1.5 to 50.4 (11.0 ± 14.7) years; weight 8.5 to 85.0 (29.7 ± 23.1) kg. chest X-ray of all patients showed increased blood in both lungs, with a cardiothoracic ratio of 0.49 to 0.65 (0.57 ± 0.05), of which 9 cases had typical radiographs. The diagnosis mainly relied on echocardiography. 7 cases had cardiovascular angiography and cardiac catheterization. 2 cases had CT examination, of which 1 case suggested right displacement of the heart and right pulmonary dysplasia. 22 patients had ectopic drainage of the right inferior pulmonary vein in 15 cases, ectopic drainage of the right pulmonary vein in 6 cases, ectopic drainage of the bilateral inferior pulmonary vein in 1 case; 18 cases had combined II foramen ovale septal defect ASD, 3 cases had right displacement of the heart, perpetual left superior vena cava 2 cases, ventricular septal defect in 1 case, arteriovenous ductus arteriosus and aortic constriction in 1 case, aortic valvular diastasis and mitral stenosis in 1 case, right pulmonary artery and right pulmonary dysplasia in 1 case. 2. Surgical method Seventeen patients used a median sternal incision, and 5 cases used a right lateral thoracic incision. One of them had a combination of ductus arteriosus and aortic stenosis, so the left side was opened first to correct the ductus arteriosus and aortic stenosis, and then the right lateral thoracic incision was performed. 16 patients were operated under extracorporeal circulation, 3 cases were operated under deep hypothermic stopping circulation, and 3 cases were not operated under extracorporeal circulation. The surgical approach varied according to the pathological and anatomical presentation of each patient. There are two broad types of surgical approaches for right pulmonary vein diversion into the left atrium: (1) intraatrial access technique: that is, an intraatrial channel is constructed in the right atrium through an atrial septal defect, and the sickle vein (scimitarvein, SV) is drained from it at the entrance to the inferior vena cava into the left atrium. This method was used in 13 patients in our group. In one patient, the atrial septum was intact and an atrial septal stoma was performed, and the inferior vena cava was incised and the septal stoma was enlarged. The right pulmonary vein was drained into the left atrium using the G0re-Tex artificial vessel as an internal channel, and the inferior vena cava was widened with an autologous pericardial piece; in one patient, the right inferior pulmonary vein opening was below the diaphragm, and the operation was performed under deep hypothermic arrest circulation, with a partial resection of the atrial septum to form a 25-mm defect, and the right pulmonary vein opening was drained from the atrium into the left atrium using an autologous pericardial piece to form an internal The right pulmonary vein opening is drained from the atrium into the left atrium with an autologous pericardial slice, and the inferior vena cava is widened with an autologous pericardial slice. (2) Direct anastomosis technique, in which the SV is cut directly from the inferior vena cava and anastomosed directly to the posterior wall of the left atrium or to the lateral wall of the right atrium and then septated into the left atrium during repair of the septal defect. This method was used in 8 patients in our group. In one of the l patients, the right inferior pulmonary vein opened below the diaphragm, the pleura was opened to free the right inferior pulmonary vein, which was dissected from the inferior vena cava and anastomosed to the right atrium. The pericardial piece was septated into the left atrium: in one case, both inferior pulmonary veins formed a common venous trunk on the right side, which was drained into the inferior vena cava. The common venous trunk was fully freed, dissected at the entrance of the inferior vena cava, and the lateral wall of the left atrium was dissected transversely. The opening of the common venous trunk is dissected into a fish-mouth shape. The anastomosis is made with the lateral wall of the left atrium, and the anastomosis is widened with an autologous pericardial piece in front of the anastomosis. Reconstruction of the atrial septum. The atrial defect was repaired; in one case, the right inferior pulmonary vein was freed outside the pericardium. The distal end was ligated and anastomosed to the left atrium with a 12-mm artificial vessel. The atrial septal defect was repaired with an autologous pericardial slice. 3 cases were repaired without extracorporeal circulation, and the right inferior pulmonary vein was free and cut at room temperature. The proximal end was sutured closed and the distal end was anastomosed with the right superior pulmonary vein. In one case, the right atrium was sutured and the atrial septal defect was sealed with a blocker under the guidance of echocardiography on the heart surface. The endotracheal tube was removed in the operating room and returned to the ward in 6 patients. 1 patient had a second endotracheal tube with pericardial drainage at 2 d postoperatively due to low cardiac output. The patient was discharged from the ventilator 5 d postoperatively. The rest of the patients had no significant complications, and all recovered well and were discharged successfully. The postoperative follow-up period for this group of cases ranged from 5 to 48 months. The average (19.8±7.5) months, X-ray chest examination suggested different degrees of cardiac reduction. The mean cardiothoracic ratio decreased to 0.52±0.04 (P<0