questions 4

Tetralogy of Fallot

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Topic updated on 06/09/17 9:22pm

Overview

Snapshot
  • A 2-week-old newborn is brought to the physician because his lips have turned blue on three occasions during feeding. His BP is 75/45, Pulse is 170, and RR is 44. A grade 3/6, harsh, systolic ejection murmur is heard at the left upper sternal border. A CXR shows a small boot-shaped heart and decreased pulmonary vascular markings.
Introduction
  • Most common cyanotic congenital cardiac abnormality
    • result of anterosuperior displacement of infundibular septum
    • caused by abnormal migration of neural crest cells 
  • Consists of four, distinct physical defects including 
    • VSD 
    • overriding aorta
      • overrides the VSD
    • pulmonary stenosis
      • most important determinant for prognosis 
        • cyanosis may or may not be present depending on degree of stenosis
    • RVH
      • result of increased afterload caused by pulmonary stenosis
  • Risk factors include
    • Down syndrome
    • cri-du-chat syndrome
    • trisomy 13/18
Presentation
  • Symptoms
    • presentations can range broadly during infancy with
      • "tet spells"
        • acute cyanosis and dyspnea that
          • develop over the first 6 months of life
          • caused by right to left shunt
            • a result of ↑ pressure caused by stenotic pulmonic valve
        • may occur during crying or when overheated or panicked
      • acyanotic "pink tet"
        • infant who has TOF but is not cyanotic is called a "pink tet"
        • degree of cyanosis depends upon 
          • severity of pulmonary stenosis
          • direction of blood flow across the VSD
      • failure to thrive
      • mental status changes
      • child adopting a squatting posture
        • increasing SVR via compression of the femoral arteries
        • improves bloodflow across the VSD
        • allows blood to enter pulmonary circulation
  • Physical Exam
    • long, harsh, systolic ejection murmur at mid-left sternal border
    • single second heart sound (S2)
    • digital clubbing
Evaluation
  • CXR shows "boot-shaped heart
Treatment
  • Prostaglandin E (PGE1)
    • keeps the ductus arteriosus patent in cyanotic newborns
      • allows collateral circulation to the lungs in spite of pulmonary stenosis
      • blood flows from the aorta through the ductus arteriosus to the pulmonary artery to the lungs
  • Surgical correction in children with a hypoxemic spells is necessary for repair


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Qbank (3 Questions)

TAG
(M1.CV.1) A 4-month-old is noted to have a grade 3/6, harsh, systolic ejection murmur heard at the left upper sternal border. The mother reports that the child's lips occasionally turn blue during feeding. A cardiologist recommends surgery. Later, the physician remarks that the infant's congenital abnormality was related to a failure of neural crest cell migration. Prior to surgery, which of the following was a likely finding? Topic Review Topic

1. Atrial septal defect
2. Pulmonic stenosis
3. Triscuspid atresia
4. Coarctation of the aorta
5. Transposition of the great vessels

PREFERRED RESPONSE ▶
TAG
(M1.CV.36) A 4-year-old Caucasian male suffers from cyanosis and dyspnea relieved by squatting. Which of the following abnormalities is most likely present? Topic Review Topic

1. Left ventricular hypertrophy
2. Atrial septal defect
3. Ventricular septal defect
4. Coarctation of the aorta
5. Patent ductus arteriosus

PREFERRED RESPONSE ▶
TAG
(M1.CV.120) A 7-year-old boy is being evaluated in pediatric cardiology clinic. He appears grossly normal, but suddenly becomes tachypneic and cyanotic when his mom takes a toy away from him. These symptoms resolve somewhat when he drops into a squatting position. Transthoracic echocardiography reveals pulmonic stenosis, a ventricular septal defect, right ventricular hypertrophy, and an overriding aorta. Which of the following best predicts the degree of cyanosis and other hypoxemic symptoms in this patient? Topic Review Topic

1. Degree of pulmonic stenosis
2. Size of ventricular septal defect (VSD)
3. Degree of right ventricular hypertrophy (RVH)
4. Degree to which aorta overrides right ventricle
5. Presence of S3

PREFERRED RESPONSE ▶
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