Tetralogy of Fallot is a congenital heart condition that affects the structure of the heart, resulting in four specific abnormalities. These abnormalities include an interventricular defect, pulmonary stenosis, biventricular aortal origin, and right ventricular hypertrophy. The discovery and description of tetralogy of Fallot can be traced back to the late 18th century. In 1777, the case of a 16-month-old patient known as the blue boy who presented with symptoms resembling asthma.
Upon autopsy, it was discovered that the child had a congenitally malformed heart with no signs of ligamentum arteriosum or ductus arteriosus. This condition is the most common cyanotic heart condition in children who have survived the neonatal period without treatment, accounting for approximately 10 percent of all congenital heart defects. Early intervention is critical in the management, with surgical correction usually performed within the first year of life. This intervention can greatly improve the quality of life for affected children and reduce the risk of long-term complications.
Epidemiology
Tetralogy of Fallot is the most frequent cyanotic heart condition in the pediatric population and typically requires corrective treatment during the first year of life. This defect occurs in about 10% of all cases of congenital heart defects and has a prevalence of 5 cases per 10,000 live births. Both males and females are equally susceptible.
Anatomy
Pathophysiology
The human heart starts developing around the 20th day of gestation when the outer endocardial tubes merge to form the cardiac tube. As development progresses, the cardiac tube folds and loops to form the ventricle and atrium. In the developing fetus, the right ventricle is the dominant chamber, receiving 65% of venous return and supplying blood to the lower body, placenta, and lungs.
In tetralogy of Fallot, the exact embryologic process causing the condition is unknown, but it involves an anterior and cephalad deviation of the infundibular septum, resulting in a misaligned ventricular septal defect and overriding aortic root, causing right ventricular outflow obstruction.
This obstruction can be caused by several factors, including a bicuspid and stenotic pulmonary valve, deviation of the infundibular septum, hypoplastic pulmonary valve annulus, or hypertrophy of muscular bands. Tet spells occur when there is a decrease in systemic vascular resistance or an increase in pulmonary resistance, resulting in a right-to-left shunt across the ventricular septal defect and severe desaturation.
Etiology
Tetralogy of Fallot’s development involves multiple factors, including untreated maternal diabetes, the intake of retinoic acid by the mother, chromosomal anomalies such as trisomies 18, 21 and 13, microdeletions of chromosome 22q11.2, phenylketonuria, and Alagille syndrome with mutations in NOTCH2 genes.
Additionally, other genetic abnormalities that increase the risk of developing tetralogy of Fallot include mutations in transcription factor NKX2.5, methylenetetrahydrofolate reductase polymorphism, as well as mutations in ZFPM2 and TBX1.
Genetics
Prognostic Factors
Clinical History
Clinical History
Tet spells, also known as hypercyanotic episodes, typically occur during infancy and tend to reduce after the age of 4 to 5 years. These episodes can be triggered by factors such as dehydration or agitation and, if left untreated, can lead to syncope, severe cyanosis, hypoxia, and even death.
Clubbing, characterized by the enlargement of the fingertips, is a rare occurrence in patients with Tet spells and is usually observed in those with long-standing and severe cyanosis.
Frequently, other cardiac abnormalities are present such as an anomalous coronary artery, right aortic arch, notable collateral vessels between the aorta and pulmonary artery, a patent ductus arteriosus, and occasionally, multiple defects in the septum and aortic valve incompetence.
Physical Examination
Physical Examination
In certain patients, cyanosis may not appear until later in life due to the progressive worsening of obstruction. During a physical examination, the first heart sound is typically normal, while the second heart sound is loud and singular. The murmur’s intensity increases with obstruction and is usually described as a harsh systolic ejection crescendo-decrescendo with radiation to the posterior left mid to upper sternal border.
Sometimes, the murmur may have a regurgitant quality, and an early systolic click may be audible along the left sternal border. In some cases, a systolic thrill and a prominent ventricular impulse may be felt, but hepatomegaly is rare. Prominent pulses may suggest the presence of aorticopulmonary collaterals or patent ductus arteriosus.
Age group
Associated comorbidity
Associated activity
Acuity of presentation
Differential Diagnoses
Differential Diagnoses
Respiratory distress
Cyanosis
Failure to thrive
Taussig-bing anomaly
Ebstein anomaly
Hypoplastic left heart syndrome
Laboratory Studies
Imaging Studies
Procedures
Histologic Findings
Staging
Treatment Paradigm
Newborns experiencing severe obstruction of right ventricle outflow may require prostaglandin therapy to preserve the duct’s patency and pulmonary flow prior to surgical repair. In cases of Tet spells, an aggressive approach is necessary, including knee-chest positioning to increase systemic vascular resistance, oxygen therapy to cause systemic vasoconstriction and pulmonary vasodilation, intravenous fluid bolus to improve pulmonary flow and right ventricle filling, intravenous beta-blockers, morphine, to relax the muscle and improve right ventricle outflow obstruction, and intravenous phenylephrine to increase systemic afterload.
Pharmacological therapeutic options such as loop diuretics and digoxin may be used if heart failure develops. Additionally, patients with unrepairable cyanotic congenital heart disease should receive prophylaxis against subacute bacterial endocarditis, especially for respiratory, dental, or infected skin procedures. Moreover, prophylaxis should be administered to patients with a history of endocarditis, prosthetic cardiac valves, and completely repaired congenital heart disease with prosthetic material or device for six months post-procedure.
Fortunately, the standardization and advancement of surgical repairing techniques and better postoperative management have significantly improved the survival rate of patients with congenital heart disease, reaching 90% by the early 1960s. This decrease in perioperative mortality demonstrates significant progress in the treatment of congenital heart disease.
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Tetralogy of Fallot is a congenital heart condition that affects the structure of the heart, resulting in four specific abnormalities. These abnormalities include an interventricular defect, pulmonary stenosis, biventricular aortal origin, and right ventricular hypertrophy. The discovery and description of tetralogy of Fallot can be traced back to the late 18th century. In 1777, the case of a 16-month-old patient known as the blue boy who presented with symptoms resembling asthma.
Upon autopsy, it was discovered that the child had a congenitally malformed heart with no signs of ligamentum arteriosum or ductus arteriosus. This condition is the most common cyanotic heart condition in children who have survived the neonatal period without treatment, accounting for approximately 10 percent of all congenital heart defects. Early intervention is critical in the management, with surgical correction usually performed within the first year of life. This intervention can greatly improve the quality of life for affected children and reduce the risk of long-term complications.
Tetralogy of Fallot is the most frequent cyanotic heart condition in the pediatric population and typically requires corrective treatment during the first year of life. This defect occurs in about 10% of all cases of congenital heart defects and has a prevalence of 5 cases per 10,000 live births. Both males and females are equally susceptible.
The human heart starts developing around the 20th day of gestation when the outer endocardial tubes merge to form the cardiac tube. As development progresses, the cardiac tube folds and loops to form the ventricle and atrium. In the developing fetus, the right ventricle is the dominant chamber, receiving 65% of venous return and supplying blood to the lower body, placenta, and lungs.
In tetralogy of Fallot, the exact embryologic process causing the condition is unknown, but it involves an anterior and cephalad deviation of the infundibular septum, resulting in a misaligned ventricular septal defect and overriding aortic root, causing right ventricular outflow obstruction.
This obstruction can be caused by several factors, including a bicuspid and stenotic pulmonary valve, deviation of the infundibular septum, hypoplastic pulmonary valve annulus, or hypertrophy of muscular bands. Tet spells occur when there is a decrease in systemic vascular resistance or an increase in pulmonary resistance, resulting in a right-to-left shunt across the ventricular septal defect and severe desaturation.
Tetralogy of Fallot’s development involves multiple factors, including untreated maternal diabetes, the intake of retinoic acid by the mother, chromosomal anomalies such as trisomies 18, 21 and 13, microdeletions of chromosome 22q11.2, phenylketonuria, and Alagille syndrome with mutations in NOTCH2 genes.
Additionally, other genetic abnormalities that increase the risk of developing tetralogy of Fallot include mutations in transcription factor NKX2.5, methylenetetrahydrofolate reductase polymorphism, as well as mutations in ZFPM2 and TBX1.
Clinical History
Tet spells, also known as hypercyanotic episodes, typically occur during infancy and tend to reduce after the age of 4 to 5 years. These episodes can be triggered by factors such as dehydration or agitation and, if left untreated, can lead to syncope, severe cyanosis, hypoxia, and even death.
Clubbing, characterized by the enlargement of the fingertips, is a rare occurrence in patients with Tet spells and is usually observed in those with long-standing and severe cyanosis.
Frequently, other cardiac abnormalities are present such as an anomalous coronary artery, right aortic arch, notable collateral vessels between the aorta and pulmonary artery, a patent ductus arteriosus, and occasionally, multiple defects in the septum and aortic valve incompetence.
Physical Examination
In certain patients, cyanosis may not appear until later in life due to the progressive worsening of obstruction. During a physical examination, the first heart sound is typically normal, while the second heart sound is loud and singular. The murmur’s intensity increases with obstruction and is usually described as a harsh systolic ejection crescendo-decrescendo with radiation to the posterior left mid to upper sternal border.
Sometimes, the murmur may have a regurgitant quality, and an early systolic click may be audible along the left sternal border. In some cases, a systolic thrill and a prominent ventricular impulse may be felt, but hepatomegaly is rare. Prominent pulses may suggest the presence of aorticopulmonary collaterals or patent ductus arteriosus.
Differential Diagnoses
Respiratory distress
Cyanosis
Failure to thrive
Taussig-bing anomaly
Ebstein anomaly
Hypoplastic left heart syndrome
Newborns experiencing severe obstruction of right ventricle outflow may require prostaglandin therapy to preserve the duct’s patency and pulmonary flow prior to surgical repair. In cases of Tet spells, an aggressive approach is necessary, including knee-chest positioning to increase systemic vascular resistance, oxygen therapy to cause systemic vasoconstriction and pulmonary vasodilation, intravenous fluid bolus to improve pulmonary flow and right ventricle filling, intravenous beta-blockers, morphine, to relax the muscle and improve right ventricle outflow obstruction, and intravenous phenylephrine to increase systemic afterload.
Pharmacological therapeutic options such as loop diuretics and digoxin may be used if heart failure develops. Additionally, patients with unrepairable cyanotic congenital heart disease should receive prophylaxis against subacute bacterial endocarditis, especially for respiratory, dental, or infected skin procedures. Moreover, prophylaxis should be administered to patients with a history of endocarditis, prosthetic cardiac valves, and completely repaired congenital heart disease with prosthetic material or device for six months post-procedure.
Fortunately, the standardization and advancement of surgical repairing techniques and better postoperative management have significantly improved the survival rate of patients with congenital heart disease, reaching 90% by the early 1960s. This decrease in perioperative mortality demonstrates significant progress in the treatment of congenital heart disease.
medtigo
Tetralogy of Fallot
Updated :
August 24, 2023
Tetralogy of Fallot is a congenital heart condition that affects the structure of the heart, resulting in four specific abnormalities. These abnormalities include an interventricular defect, pulmonary stenosis, biventricular aortal origin, and right ventricular hypertrophy. The discovery and description of tetralogy of Fallot can be traced back to the late 18th century. In 1777, the case of a 16-month-old patient known as the blue boy who presented with symptoms resembling asthma.
Upon autopsy, it was discovered that the child had a congenitally malformed heart with no signs of ligamentum arteriosum or ductus arteriosus. This condition is the most common cyanotic heart condition in children who have survived the neonatal period without treatment, accounting for approximately 10 percent of all congenital heart defects. Early intervention is critical in the management, with surgical correction usually performed within the first year of life. This intervention can greatly improve the quality of life for affected children and reduce the risk of long-term complications.
Tetralogy of Fallot is the most frequent cyanotic heart condition in the pediatric population and typically requires corrective treatment during the first year of life. This defect occurs in about 10% of all cases of congenital heart defects and has a prevalence of 5 cases per 10,000 live births. Both males and females are equally susceptible.
The human heart starts developing around the 20th day of gestation when the outer endocardial tubes merge to form the cardiac tube. As development progresses, the cardiac tube folds and loops to form the ventricle and atrium. In the developing fetus, the right ventricle is the dominant chamber, receiving 65% of venous return and supplying blood to the lower body, placenta, and lungs.
In tetralogy of Fallot, the exact embryologic process causing the condition is unknown, but it involves an anterior and cephalad deviation of the infundibular septum, resulting in a misaligned ventricular septal defect and overriding aortic root, causing right ventricular outflow obstruction.
This obstruction can be caused by several factors, including a bicuspid and stenotic pulmonary valve, deviation of the infundibular septum, hypoplastic pulmonary valve annulus, or hypertrophy of muscular bands. Tet spells occur when there is a decrease in systemic vascular resistance or an increase in pulmonary resistance, resulting in a right-to-left shunt across the ventricular septal defect and severe desaturation.
Tetralogy of Fallot’s development involves multiple factors, including untreated maternal diabetes, the intake of retinoic acid by the mother, chromosomal anomalies such as trisomies 18, 21 and 13, microdeletions of chromosome 22q11.2, phenylketonuria, and Alagille syndrome with mutations in NOTCH2 genes.
Additionally, other genetic abnormalities that increase the risk of developing tetralogy of Fallot include mutations in transcription factor NKX2.5, methylenetetrahydrofolate reductase polymorphism, as well as mutations in ZFPM2 and TBX1.
Clinical History
Tet spells, also known as hypercyanotic episodes, typically occur during infancy and tend to reduce after the age of 4 to 5 years. These episodes can be triggered by factors such as dehydration or agitation and, if left untreated, can lead to syncope, severe cyanosis, hypoxia, and even death.
Clubbing, characterized by the enlargement of the fingertips, is a rare occurrence in patients with Tet spells and is usually observed in those with long-standing and severe cyanosis.
Frequently, other cardiac abnormalities are present such as an anomalous coronary artery, right aortic arch, notable collateral vessels between the aorta and pulmonary artery, a patent ductus arteriosus, and occasionally, multiple defects in the septum and aortic valve incompetence.
Physical Examination
In certain patients, cyanosis may not appear until later in life due to the progressive worsening of obstruction. During a physical examination, the first heart sound is typically normal, while the second heart sound is loud and singular. The murmur’s intensity increases with obstruction and is usually described as a harsh systolic ejection crescendo-decrescendo with radiation to the posterior left mid to upper sternal border.
Sometimes, the murmur may have a regurgitant quality, and an early systolic click may be audible along the left sternal border. In some cases, a systolic thrill and a prominent ventricular impulse may be felt, but hepatomegaly is rare. Prominent pulses may suggest the presence of aorticopulmonary collaterals or patent ductus arteriosus.
Differential Diagnoses
Respiratory distress
Cyanosis
Failure to thrive
Taussig-bing anomaly
Ebstein anomaly
Hypoplastic left heart syndrome
Newborns experiencing severe obstruction of right ventricle outflow may require prostaglandin therapy to preserve the duct’s patency and pulmonary flow prior to surgical repair. In cases of Tet spells, an aggressive approach is necessary, including knee-chest positioning to increase systemic vascular resistance, oxygen therapy to cause systemic vasoconstriction and pulmonary vasodilation, intravenous fluid bolus to improve pulmonary flow and right ventricle filling, intravenous beta-blockers, morphine, to relax the muscle and improve right ventricle outflow obstruction, and intravenous phenylephrine to increase systemic afterload.
Pharmacological therapeutic options such as loop diuretics and digoxin may be used if heart failure develops. Additionally, patients with unrepairable cyanotic congenital heart disease should receive prophylaxis against subacute bacterial endocarditis, especially for respiratory, dental, or infected skin procedures. Moreover, prophylaxis should be administered to patients with a history of endocarditis, prosthetic cardiac valves, and completely repaired congenital heart disease with prosthetic material or device for six months post-procedure.
Fortunately, the standardization and advancement of surgical repairing techniques and better postoperative management have significantly improved the survival rate of patients with congenital heart disease, reaching 90% by the early 1960s. This decrease in perioperative mortality demonstrates significant progress in the treatment of congenital heart disease.
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