Tetralogy of Fallot Narisha Ali, MS, PA-C

GENERAL FEATURES • Most common form of cyanotic congenital heart disease with an incidence rate of 1 in 3,600 births { Caused by a combination of four anatomical heart defects, resulting in the flow of oxygen-poor blood out of the heart and into the rest of the body, causing cyanotic (bluish) discoloration of the skin  Pulmonary valve stenosis: narrowing of the pulmonary valve (between the right ventricle and pulmonary artery) leads to reduced blood flow to the lungs  Ventricular septal defect (VSD): a hole in the wall (septum) separating the ventricles lets deoxygenated blood in the right ventricle flow into the left ventricle and mix with oxygenated blood from the lungs  Overriding aorta: abnormal positioning of the aorta directly above the VSD instead of only branching off of the left ventricle. This causes the aorta to receive oxygen-poor blood from the right ventricle and oxygen-rich blood from the left ventricle.  Right ventricular hypertrophy: enlargement and thickening of the right ventricle's muscular wall • If the patient also has an atrial septal defect, the condition is known as Pentalogy of Fallot. • Although the exact cause of Tetralogy of Fallot is unknown, risk factors include: { Maternal viral illness (such as rubella) during pregnancy { Maternal alcohol abuse during pregnancy { Poor maternal nutrition during pregnancy { Maternal age > 40 years { A parent with Tetralogy of Fallot { Down syndrome or DiGeorge syndrome (15% of patients with Tetralogy of Fallot also have these associated syndromes) { Methylenetetrahydrofolate reductase polymorphism • Diagnosis is generally made by echocardiogram. • The 40-year survival rate is at least 90%. Narisha Ali practices at Memorial Sloan Kettering Cancer Center in New York City and Long Island Jewish Medical Center in New Hyde Park, N.Y. The author has disclosed no potential conflicts of interest, financial or otherwise. Dawn Colomb-Lippa, MHS, PA-C, department editor DOI: 10.1097/01.JAA.0000462058.86000.b6 Copyright © 2015 American Academy of Physician Assistants

CLINICAL ASSESSMENT • Signs and symptoms vary depending on the severity of defects and the extent of blood flow obstruction. Tiring easily during play and clubbing of fingers and toes are found at all levels of obstruction. { Severe obstruction—cyanosis evident in the immediate newborn period { Moderate obstruction  Heart murmur due to right ventricular outflow obstruction Crescendo-decrescendo with a harsh systolic ejection quality QUESTIONS 1. A 42-year-old woman gives birth via spontaneous vaginal delivery to a healthy baby boy; they are discharged home after 2 days. Two weeks later, she presents to the local ED after her baby turns blue and becomes short of breath while breastfeeding. A heart murmur is auscultated and the infant has clubbing of the fingers and toes. Which of the following echocardiogram findings best supports a diagnosis of Tetralogy of Fallot? a. two parallel great vessels, VSD, pulmonary valve stenosis b. VSD, atrial septal defect, coarctation of the aorta c. right ventricular hypertrophy, patent ductus arteriosus, pulmonary valve stenosis d. VSD, pulmonary valve stenosis, overriding aorta, right ventricular hypertrophy 2. A father calls 911 after his 3-month-old daughter (who was delivered naturally after a full-term pregnancy) lost consciousness for about 1 minute. He states that before she lost consciousness, the infant was crying; he also has noticed a deep blue discoloration of her skin, nails, and lips. An echocardiogram reveals narrowing of the pulmonary valve, VSD, right ventricular hypertrophy, and abnormal positioning of the aorta directly above the VSD. What anatomical defect would make this a diagnosis of Pentalogy of Fallot, and which treatment is most effective? a. b. c. d.

patent ductus arteriosus and intracardiac repair atrial septal defect and intracardiac repair patent ductus arteriosus and shunt placement atrial septal defect and shunt placement

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TREATMENT • All children with Tetralogy of Fallot need corrective surgery, which is the only effective treatment. { Intracardiac repair is an open-heart surgery typically performed during the first year of life.  A patch is placed over the VSD to close it.  The narrowed pulmonary valve is repaired and the pulmonary artery is widened to increase blood flow to the lungs. { Temporary surgery may be performed before intracardiac repair for premature infants or those with an underdeveloped pulmonary artery.  A shunt to increase blood flow to the lungs is created by placing a tube between a large artery branching off the aorta and the pulmonary artery.  The shunt is removed when the infant’s heart defects are fixed during full repair.

1. D. Tetralogy of Fallot is defined as pulmonary valve stenosis, VSD, right ventricular hypertrophy, and an overriding aorta. Two parallel great vessels is a finding consistent with the congenital heart defect transposition of the great arteries. Coarctation of the aorta is an acyanotic defect that should not be confused with an overriding aorta. The ductus arteriosus is a fetal blood vessel that normally closes at birth; patent ductus arteriosus is not a defect in Tetralogy of Fallot.

DIAGNOSIS • The three main tests for diagnosis are chest radiograph, ECG, and echocardiogram { Chest radiograph findings  A“boot-shaped” heart, specifically an upturned cardiac apex due to right ventricular hypertrophy, and a concave pulmonary arterial segment  A right aortic arch in 25% of patients { An ECG is used to assess right ventricular hypertrophy, which is characterized by right axis deviation (>90 degrees), tall R waves in right ventricular leads, deep S waves in left ventricular leads, and a slight increase in QRS duration. { An echocardiogram can show the presence of a VSD, pulmonic valve structure, right ventricular function, and whether the aorta is positioned properly. • A complete blood cell count will show erythrocytosis (an abnormally high red blood cell count), indicating the body’s attempt to increase the oxygen level in the blood. • Pulse oximetry is used to measure the oxygen level in the blood. Patients with Tetralogy of Fallot typically have an SpO2 of less than 90%.

• Cardiac catheterization may be necessary to further delineate the cardiac structure.

2. B. The Pentalogy of Fallot consists of pulmonary valve stenosis, VSD, right ventricular hypertrophy, overriding aorta, and atrial septal defect. Placement of a shunt is a temporary fix; the shunt is removed once intracardiac repair is completed. Therefore, intracardiac repair is the most effective treatment for Tetralogy or Pentalogy of Fallot.

Located in the left mid to upper sternal border with radiation posteriorly  Tet spells More common in infants ages 2 to 4 months Occur after feeding, a bowel movement, or the infant kicking his or her legs upon wakening Child becomes deep blue due to a rapid decrease in the amount of oxygen in the blood. May appear very irritable or cry, may be tachypneic, and may lose consciousness.  Failed oximetry screening test (SpO less than 90%) 2 { Mild obstruction  Tired with feeding  Poor weight gain

Volume 28 • Number 6 • June 2015

Copyright © 2015 American Academy of Physician Assistants

Tetralogy of Fallot.

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