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Anomalous pulmonary venous connection | |
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Illustration of total anomalous pulmonary venous connection | |
Specialty | Medical genetics |
Anomalous pulmonary venous connection (or anomalous pulmonary venous drainage or anomalous pulmonary venous return [1] ) is a congenital heart defect of the pulmonary veins. It can be a total anomalous pulmonary venous connection, wherein all four pulmonary veins are incorrectly positioned, or a partial anomalous pulmonary venous connection, wherein only some of the pulmonary veins are incorrectly positioned.
Total anomalous pulmonary venous connection, also known as total anomalous pulmonary venous return, is a rare cyanotic congenital heart defect in which all four pulmonary veins are malpositioned and make anomalous connections to the systemic venous circulation. A right-to-left shunt such as a patent foramen ovale, patent ductus arteriosus or an atrial septal defect must be present, or else the condition is fatal due to a lack of systemic blood flow.[ citation needed ]
In some cases, it can be detected prenatally. [2]
There are four variants: Supracardiac (50%): blood drains to one of the innominate veins (brachiocephalic veins), azygous vein or the superior vena cava; Cardiac (20%), where blood drains into coronary sinus or directly into the right atrium; Infradiaphragmatic (20%), where blood drains into portal or hepatic veins; and a mixed (10%) variant, which can be a combination of any of the above connections. [3]
TAPVC is further characterized on the presence or absence of obstruction, which occurs when the anomalous vein enters a vessel at an acute angle and can cause pulmonary venous hypertension and cyanosis because blood cannot enter the new vein as easily.[ citation needed ]
The diagnosis of TAPVC is dependent upon whether or not there is an obstruction. [4]
TAPVC with obstruction will clinically present with cyanosis, tachypnea, dyspnea, and hypoxemia. Chest x-ray may show a ground-glass appearance due to pulmonary edema resulting from increased pressure in the obstructed pulmonary veins.
Cases of TAPVC with obstruction are considered a surgical emergency.
In TAPVC without obstruction, surgical redirection can be performed within the first month of life. The operation is performed under general anesthesia. The four pulmonary veins are reconnected to the left atrium, and any associated heart defects such as atrial septal defect, ventricular septal defect, patent foramen ovale, and/or patent ductus arteriosus are surgically closed. With obstruction, surgery should be undertaken emergently. PGE1 should be given because a patent ductus arteriosus allows oxygenated blood to go from the circulation of the right heart to the systemic circulation.[ citation needed ]
A Partial anomalous pulmonary venous connection (or Partial anomalous pulmonary venous drainage or Partial anomalous pulmonary venous return) is a congenital defect where the left atrium is the point of return for the blood from some (but not all) of the pulmonary veins.[ citation needed ]
It is less severe than total anomalous pulmonary venous connection which is a life-threatening anomaly requiring emergent surgical correction, usually diagnosed in the first few days of life. Partial anomalous venous connection may be diagnosed at any time from birth to old age. The severity of symptoms, and thus the likelihood of diagnosis, varies significantly depending on the amount of blood flow through the anomalous connections. In less severe cases, with smaller amounts of blood flow, diagnosis may be delayed until adulthood, when it can be confused with other causes of pulmonary hypertension. [5] There is also evidence that a significant number of mild cases are never diagnosed, or diagnosed incidentally. [6] It is associated with other vascular anomalies, and some genetic syndromes such as Turner syndrome.[ citation needed ]
It can be diagnosed with CT scan, angiography, transesophageal echocardiography, or cardiac MRI. [7] [8] Unfortunately, less invasive and expensive testing, such as transthoracic echocardiography and CT scanning are generally less sensitive.[ citation needed ]
It is sometimes treated with surgery, which involves rerouting blood from the right atrium into the left atrium with a patch or use of the Warden procedure. [9] [10] However, interest is increasing in catheter-based interventional approaches, as well as medical therapy for less severe cases[ citation needed ].
To understand the different types of anomalous pulmonary venous connection, it is important to establish the background in which normal fetal vasculature develops.
During embryonic development, the lungs start as outgrowths from the foregut and share its splanchnic vascular plexus. At around 25 to 27 days of gestation, there are no direct links to the heart. By 27 to 29 days of gestation, the primitive pulmonary vein begins to form as an outgrowth from the left atrium and eventually connects with the primitive pulmonary venous system.
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:
Patent ductus arteriosus (PDA) is a medical condition in which the ductus arteriosus fails to close after birth: this allows a portion of oxygenated blood from the left heart to flow back to the lungs through the aorta, which has a higher blood pressure, to the pulmonary artery, which has a lower blood pressure. Symptoms are uncommon at birth and shortly thereafter, but later in the first year of life there is often the onset of an increased work of breathing and failure to gain weight at a normal rate. With time, an uncorrected PDA usually leads to pulmonary hypertension followed by right-sided heart failure.
dextro-Transposition of the great arteries is a potentially life-threatening birth defect in the large arteries of the heart. The primary arteries are transposed.
Atrial septal defect (ASD) is a congenital heart defect in which blood flows between the atria of the heart. Some flow is a normal condition both pre-birth and immediately post-birth via the foramen ovale; however, when this does not naturally close after birth it is referred to as a patent (open) foramen ovale (PFO). It is common in patients with a congenital atrial septal aneurysm (ASA).
A congenital heart defect (CHD), also known as a congenital heart anomaly, congenital cardiovascular malformation, and congenital heart disease, is a defect in the structure of the heart or great vessels that is present at birth. A congenital heart defect is classed as a cardiovascular disease. Signs and symptoms depend on the specific type of defect. Symptoms can vary from none to life-threatening. When present, symptoms are variable and may include rapid breathing, bluish skin (cyanosis), poor weight gain, and feeling tired. CHD does not cause chest pain. Most congenital heart defects are not associated with other diseases. A complication of CHD is heart failure.
A ventricular septal defect (VSD) is a defect in the ventricular septum, the wall dividing the left and right ventricles of the heart. The extent of the opening may vary from pin size to complete absence of the ventricular septum, creating one common ventricle. The ventricular septum consists of an inferior muscular and superior membranous portion and is extensively innervated with conducting cardiomyocytes.
Eisenmenger syndrome or Eisenmenger's syndrome is defined as the process in which a long-standing left-to-right cardiac shunt caused by a congenital heart defect causes pulmonary hypertension and eventual reversal of the shunt into a cyanotic right-to-left shunt. Because of the advent of fetal screening with echocardiography early in life, the incidence of heart defects progressing to Eisenmenger syndrome has decreased.
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.
Pulmonary atresia is a congenital malformation of the pulmonary valve in which the valve orifice fails to develop. The valve is completely closed thereby obstructing the outflow of blood from the heart to the lungs. The pulmonary valve is located on the right side of the heart between the right ventricle and pulmonary artery. In a normal functioning heart, the opening to the pulmonary valve has three flaps that open and close.
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 is contracted 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.
Levo-Transposition of the great arteries is an acyanotic congenital heart defect in which the primary arteries are transposed, with the aorta anterior and to the left of the pulmonary artery; the morphological left and right ventricles with their corresponding atrioventricular valves are also transposed.
Pulmonic stenosis, is a dynamic or fixed obstruction of flow from the right ventricle of the heart to the pulmonary artery. It is usually first diagnosed in childhood.
Cor triatriatum is a congenital heart defect where the left atrium or right atrium is subdivided by a thin membrane, resulting in three atrial chambers.
Scimitar syndrome, or congenital pulmonary venolobar syndrome, is a rare congenital heart defect characterized by anomalous venous return from the right lung. This anomalous pulmonary venous return can be either partial (PAPVR) or total (TAPVR). The syndrome associated with PAPVR is more commonly known as Scimitar syndrome after the curvilinear pattern created on a chest radiograph by the pulmonary veins that drain to the inferior vena cava. This radiographic density often has the shape of a scimitar, a type of curved sword. The syndrome was first described by Catherine Neill in 1960.
A right-to-left shunt is a cardiac shunt which allows blood to flow from the right heart to the left heart. This terminology is used both for the abnormal state in humans and for normal physiological shunts in reptiles.
Interrupted aortic arch is a very rare heart defect in which the aorta is not completely developed. There is a gap between the ascending and descending thoracic aorta. In a sense it is the complete form of a coarctation of the aorta. Almost all patients also have other cardiac anomalies, including a ventricular septal defect (VSD), aorto-pulmonary window, and truncus arteriosus. There are three types of interrupted aortic arch, with type B being the most common. Interrupted aortic arch is often associated with DiGeorge syndrome.
Anomalous aortic origin of a coronary artery (AAOCA) is a rare congenital heart defect in which a coronary artery inappropriately arises from the aorta, usually from the incorrect sinus of Valsalva. This anomalous coronary artery often takes an interarterial, intraconal, or intramural course, and is associated with an increased risk of sudden death in children.
Pulmonary atresia with ventricular septal defect is a rare birth defect characterized by pulmonary valve atresia occurring alongside a defect on the right ventricular outflow tract.
Raghib syndrome is rare a congenital heart defect where the left superior vena cava (LSVC) is draining into the left atrium in addition to an absent coronary sinus and an atrial septal defect. This can be considered a dangerous heart condition because it puts the individual at a high risk of stroke. Other defects that are often associated with Raghib syndrome can include ventricular septal defects, enlargement of the tricuspid annulus, and pulmonary stenosis. While this is considered an extremely rare developmental complex, cases regarding a persistent left superior vena cava (PLSVC) are relatively common among congenital heart defects. It is also important to note that the PLSVC often drains into the right atrium, and only drains into the left atrium in approximately 10 to 20% of individuals with the defect.