Norwood procedure | |
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ICD-9-CM | 35.8 |
The Norwood procedure is the first of three palliative surgeries for patients with hypoplastic left heart syndrome (HLHS) and other complex heart defects with single ventricle physiology intended to create a new functional single ventricle system. [1] The first successful Norwood procedure involving the use of a cardiopulmonary bypass was reported by Dr. William Imon Norwood, Jr. and colleagues in 1981. [2] [3]
Variations of the Norwood procedure, or Stage 1 palliation, have been proposed and adopted over the last 30 years; however, its basic components have remained unchanged. The purpose of the procedure is to utilize the right ventricle as the main chamber pumping blood to the body and lungs. A connection between left and right atria (collecting chambers of the heart) is established via atrial septectomy, allowing blood arriving from the lungs to travel to the right ventricle. Next a connection between the right ventricle and aorta is created using a tissue graft from the main pulmonary artery. [4] Lastly, an aortopulmonary shunt is created to provide blood flow to the lungs from the systemic circulation. The most common shunts are the Modified Blalock Taussig shunt (MBTS) or right ventricle- to pulmonary artery shunt (RVPA or Sano shunt).
Most patients who undergo a Norwood procedure will proceed to further stages of single ventricle palliation. A second surgery, also known as the Glenn procedure, occurs at 4-6 months of age. The third surgery is the Fontan procedure, occurring when patients are 3-5 years of age. [5]
Norwood procedure is most commonly performed to treat hypoplastic left heart syndrome, double outlet right ventricle, double inlet left ventricle, and other single ventricle congenital heart defects. [6] Variations are also used for palliation of mitral and tricuspid atresia [7] and subsets of transposition of great arteries (TGA). [8]
Without surgical repair, infants born with a single ventricle cardiac defect face almost certain mortality in the first year of life. [9] [10] [11] In these conditions, the most urgent problem is that the heart is unable to pump blood to the systemic circulation (i.e. to the body). The goal of these three surgeries is to ultimately connect the single ventricle to the systemic circulation. To accomplish this, blood flow to the lungs is disrupted, and therefore an alternative path must be created to provide blood flow to the lungs. [12]
There are numerous factors that increase the risk of the Norwood procedure and are relative contraindications. Those factors include Low birth weight, extremely premature delivery, poor ventricular function, Intraventricular hemorrhage, severe non-cardiac congenital defects, and genetic syndromes with poor prognosis. [6]
While the Norwood procedure is the standard of care for single ventricle cardiac defects, there are other treatment options for patients depending on their unique anatomy. [13] One option is the Hybrid procedure which is done via cardiac catheterization and surgery. [14] [15] A stent is placed in the ductus arteriosus to keep it patent and bands are placed over both the left and right pulmonary arteries to limit pressure and over-circulation to the lungs. [16] Another option is cardiac transplantation, although this is uncommon due to the limited availability of neonatal donor hearts. [17] [18] Families can also elect to pursue comfort care for their newborns, especially if there are concomitant anatomic defects or genetic syndromes with poor prognosis. [10] [19]
Entry to the body cavity for the Norwood procedure is gained by a vertical incision above the sternum. Separation of the sternum is necessary. This surgery is complex and may vary slightly depending on the diagnosis and overall condition of the heart. The surgery on the heart can be divided into two main steps. [20]
The main pulmonary artery is separated from the left and right portions of the pulmonary artery and joined with the upper portion of the aorta. Widening of the pulmonary artery is often necessary, and may be accomplished by using the patient's existing biological tissue, or appropriate animal tissue. This allows the blood, a mixture of oxygenated and deoxygenated, to be pumped to the body via the morphologic right ventricle, through the pulmonary valve. At this point in the surgery, the right ventricle is directly connected to systemic circulation through the Neoaorta or the reconstructed aortic outflow track. Second step of the procedure establishes blood flow to the lungs. [21]
Variations to this step have been proposed over the years, however only two have been adapted in general practice over the last 20 years. In both cases a conduit is used to direct blood flow into the lungs, however anatomic anchoring varies. There are two different types of shunts used during the procedure: Modified Blalock Taussig or (MBTS) and right ventricle- to pulmonary artery shunt (RVPA or Sano shunt). MBTS shunt provides connection from the pulmonary artery to brachiocephalic artery or subclavian artery, while the RVPA conduit provides connection from right ventricle to pulmonary artery. [22] [5]
The Single Ventricle Reconstruction conducted in 2005 compared the two conduits at one, three and five year intervals. Although RVPA shunts performed better at the one and three year end points, five year follow up demonstrated no difference between survival or improvement in freedom from transplantation. [23]
After Norwood procedure infants enter the interstage which typically lasts up to 5 months. During this period the patients are medically optimized using diuretics and vasodilators. [24]
The Norwood procedure is a complex and high-risk surgery with high rates of morbidity and mortality despite advancements in surgical technique, perioperative care, and postoperative monitoring. [25]
Immediate post surgical complications have been reported by multiple studies to involve hemorrhage, vocal cord paralysis due to close proximity of the recurrent laryngeal nerve to the cardiac sack, cardiac arrhythmias as a result of potential cardiac tissue manipulation and damage, and protein-losing enteropathy. [26] [27] Other surgical complications include low cardiac output syndrome, atrioventricular valve regurgitation, aortic valve insufficiency, ventricular dysfunction, seizures, stroke, shunt thrombosis, infection, cardiac arrest, and death. [27] [28]
The interstage period is the period after the Norwood procedure and before stage II pallation (Glenn procedure, typically 4-6 months of age). This time is very high-risk for infants because the single ventricle must pump to both the systemic and pulmonary circulations, with mortality rates ranging from 2%-20%. [25] [29]
Due to the balance required to maintain adequate blood flow to the systemic and pulmonary circulations, infants in the interstage period face multiple risks:
Long-term survival rates for children with single ventricle physiology are improving as medical and surgical advancements continue. In the major SVR study (Single Ventricle Reconstruction) the transplant-free survival rate was only 54-59% amongst patients who underwent the Norwood procedure. [34] These patients experience ongoing health challenges and require lifelong cardiology follow-up. [30]
Children with single-ventricle physiology who undergo the Norwood procedure often experience neurodevelopmental impairment. [35] Neurodevelopmental and behavioral impairments are the most common long-term morbidity for children with single ventricle cardiac defects. [36] Children's hospitals have begun to implement multidisciplinary neurodevelopmental care teams as part of the standard of care for this population. [37] The impact of these interventional programs remains an active area of research. [37]
Factors affecting neurodevelopment in these children include: [35] [38]
Children who undergo the Norwood procedure may experience a range of neurodevelopmental issues, such as:
First ever series of documented Norwood procedures were performed by Dr. William Imon Norwood between 1979 and 1981. [43] Dr. Norwood was an American physician who completed his fellowship in cardiothoracic pediatric surgery at Boston Children's Medical Center (BCMC), Boston Massachusetts. [44] During his time at BCMC he became interested in the most complex congenital heart defects, particularly HLHS. Under direct supervision of his program mentor Dr. Aldo Castanedo, he performed and later perfected what would become the three stage Norwood palliation. After successful publication of his work in 1981, Dr. Norwood joined the Project Hope stationed in Krakow, Poland. There, he continued to develop and refine his work: he was responsible for Poland's first ever Fontan procedure in a patient with single ventricle pathology. [45]
Cardiology is the study of the heart. Cardiology is a branch of medicine that deals with disorders of the heart and the cardiovascular system. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease, and electrophysiology. Physicians who specialize in this field of medicine are called cardiologists, a sub-specialty of internal medicine. Pediatric cardiologists are pediatricians who specialize in cardiology. Physicians who specialize in cardiac surgery are called cardiothoracic surgeons or cardiac surgeons, a specialty of general surgery.
Tetralogy of Fallot (TOF), formerly known as Steno-Fallot tetralogy, is a congenital heart defect characterized by four specific cardiac defects. Classically, the four defects are:
The Fontan procedure or Fontan–Kreutzer procedure is a palliative surgical procedure used in children with univentricular hearts. It involves diverting the venous blood from the inferior vena cava (IVC) and superior vena cava (SVC) to the pulmonary arteries. The procedure varies for differing congenital heart pathologies. For example, in tricuspid atresia, the procedure can be done where the blood does not pass through the morphologic right ventricle; i.e., the systemic and pulmonary circulations are placed in series with the functional single ventricle. By contrast, in hypoplastic left heart syndrome, the heart is more reliant on the more functional right ventricle to provide blood flow to the systemic circulation. The procedure was initially performed in 1968 by Francis Fontan and Eugene Baudet from Bordeaux, France, published in 1971, simultaneously described in July 1971 by Guillermo Kreutzer from Buenos Aires, Argentina, presented at the Argentinean National Cardilogy meeting of that year and finally published in 1973.
The Blalock–Thomas–Taussig shunt, previously known as the Blalock–Taussig Shunt, is a surgical procedure used to increase blood flow to the lungs in some forms of congenital heart disease such as pulmonary atresia and tetralogy of Fallot, which are common causes of blue baby syndrome. The procedure involves connecting a branch of the subclavian artery or carotid artery to the pulmonary artery. In modern practice, this procedure is temporarily used to direct blood flow to the lungs and relieve cyanosis while the infant is waiting for corrective or definitive surgery when their heart is larger. The BTT shunt is used in the first step of the three-stage palliation.
Situs ambiguus, or heterotaxy, is a rare congenital defect in which the major visceral organs are distributed abnormally within the chest and abdomen. Clinically, heterotaxy spectrum generally refers to any defect of left-right asymmetry and arrangement of the visceral organs; however, classical heterotaxy requires multiple organs to be affected. This does not include the congenital defect situs inversus, which results when arrangement of all the organs in the abdomen and chest are mirrored, so the positions are opposite the normal placement. Situs inversus is the mirror image of situs solitus, which is normal asymmetric distribution of the abdominothoracic visceral organs. Situs ambiguus can also be subdivided into left-isomerism and right isomerism based on the defects observed in the spleen, lungs and atria of the heart.
Hypoplastic left heart syndrome (HLHS) is a rare congenital heart defect in which the left side of the heart is severely underdeveloped and incapable of supporting the systemic circulation. It is estimated to account for 2-3% of all congenital heart disease. Early signs and symptoms include poor feeding, cyanosis, and diminished pulse in the extremities. The etiology is believed to be multifactorial resulting from a combination of genetic mutations and defects resulting in altered blood flow in the heart. Several structures can be affected including the left ventricle, aorta, aortic valve, or mitral valve all resulting in decreased systemic blood flow.
Transposition of the great vessels (TGV) is a group of congenital heart defects involving an abnormal spatial arrangement of any of the great vessels: superior and/or inferior venae cavae, pulmonary artery, pulmonary veins, and aorta. Congenital heart diseases involving only the primary arteries belong to a sub-group called transposition of the great arteries (TGA), which is considered the most common congenital heart lesion that presents in neonates.
Tricuspid atresia is a form of congenital heart disease whereby there is a complete absence of the tricuspid valve. Therefore, there is an absence of right atrioventricular connection. This leads to a hypoplastic (undersized) or absent right ventricle. This defect occurs during prenatal development, when the heart does not finish developing. It causes the systemic circulation to be filled with relatively deoxygenated blood. The causes of tricuspid atresia are unknown.
Aortic valvuloplasty, also known as balloon aortic valvuloplasty (BAV), is a procedure used to improve blood flow through the aortic valve in conditions that cause aortic stenosis, or narrowing of the aortic valve. It can be performed in various patient populations including fetuses, newborns, children, adults, and pregnant women. The procedure involves using a balloon catheter to dilate the narrowed aortic valve by inflating the balloon.
A double inlet left ventricle (DILV) or "single ventricle", is a congenital heart defect appearing in 5 in 100,000 newborns, where both the left atrium and the right atrium feed into the left ventricle. The right ventricle is hypoplastic or does not exist.
The bidirectional Glenn (BDG) shunt, or bidirectional cavopulmonary anastomosis, is a surgical technique used in pediatric cardiac surgery procedure used to temporarily improve blood oxygenation for patients with a congenital cardiac defect resulting in a single functional ventricle. Creation of a bidirectional shunt reduces the amount of blood volume that the heart needs to pump at the time of surgical repair with the Fontan procedure.
Hypoplastic right heart syndrome (HRHS) is a congenital heart defect in which the structures on the right side of the heart, particularly the right ventricle, are underdeveloped. This defect causes inadequate blood flow to the lungs, and thus a cyanotic infant.
Anomalous left coronary artery from the pulmonary artery is a rare congenital anomaly occurring in approximately 1 in 300,000 liveborn children. The diagnosis comprises between 0.24 and 0.46% of all cases of congenital heart disease. The anomalous left coronary artery (LCA) usually arises from the pulmonary artery instead of the aortic sinus. In fetal life, the high pressure in the pulmonic artery and the fetal shunts enable oxygen-rich blood to flow in the LCA. By the time of birth, the pressure will decrease in the pulmonic artery and the child will have a postnatal circulation. The myocardium, which is supplied by the LCA, will therefore be dependent on collateral blood flow from the other coronary arteries, mainly the RCA. Because the pressure in RCA exceeds the pressure in LCA a collateral circulation will increase. This situation ultimately can lead to blood flowing from the RCA into the LCA retrograde and into the pulmonary artery, thus forming a left-to-right shunt.
A Sano shunt is a shunt from the right ventricle to the pulmonary circulation.
A hybrid cardiac surgical procedure in a narrow sense is defined as a procedure that combines a conventional, more invasive surgical part with an interventional part, using some sort of catheter-based procedure guided by fluoroscopy imaging in a hybrid operating room (OR) without interruption. The hybrid technique has a reduced risk of surgical complications and has shown decreased recovery time. It can be used to treat numerous heart diseases and conditions and with the increasing complexity of each case, the hybrid surgical technique is becoming more common.
Fetal aortic stenosis is a disorder that occurs when the fetus’ aortic valve does not fully open during development. The aortic valve is a one way valve that is located between the left ventricle and the aorta, keeping blood from leaking back into the ventricle. It has three leaflets that separate when the ventricle contracts to allow blood to move from the ventricle to the aorta. These leaflets come together when the ventricle relaxes.
The Damus–Kaye–Stansel (DKS) procedure is a cardiovascular surgical procedure used as part of the repair of some congenital heart defects. This procedure joins the pulmonary artery and the aorta in situations where the systemic circulation is obstructed. It is commonly used when a patient has the combination of a small left ventricle and a transposition of the great arteries (TGA); in this case, the procedure allows blood to flow from the left ventricle to the aorta.
The Yasui procedure is a pediatric heart operation used to bypass the left ventricular outflow tract (LVOT) that combines the aortic repair of the Norwood procedure and a shunt similar to that used in the Rastelli procedure in a single operation. It is used to repair defects that result in the physiology of hypoplastic left heart syndrome even though both ventricles are functioning normally. These defects are common in DiGeorge syndrome and include interrupted aortic arch and LVOT obstruction (IAA/LVOTO); aortic atresia-severe stenosis with ventricular septal defect (AA/VSD); and aortic atresia with interrupted aortic arch and aortopulmonary window. This procedure allows the surgeon to keep the left ventricle connected to the systemic circulation while using the pulmonary valve as its outflow valve, by connecting them through the ventricular septal defect. The Yasui procedure includes a modified Damus–Kaye–Stansel procedure to connect the aortic and pulmonary roots, allowing the coronary arteries to remain perfused. It was first described in 1987.
William Imon Norwood Jr., also Bill Norwood, was an American pediatric cardiac surgeon and physician. He was known for the Norwood procedure, a pioneering cardiac operation named after him for children born with Hypoplastic left heart syndrome.
Single ventricle is a rare congenital heart defect, which constitutes just over 1% of congenital cardiovascular diseases. The single functional ventricle could be morphologically right or left with the second ventricle usually hypoplastic and/or insufficiently functional. Therefore, there are several subtypes of the disease, depending on which ventricle is underdeveloped.