Tetralogy of Fallot, pediatric

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Overview
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A combination of four cardiac defects: ventricular septal defect (VSD); right ventricular outflow tract obstruction (pulmonary stenosis); right ventricular hypertrophy; and dextroposition of the aorta, with overriding of the VSD (see The four defects of tetralogy)
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Overview-Pathophysiology
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Blood shunts right to left through the VSD, permitting unoxygenated blood to mix with oxygenated blood, resulting in various degrees of arterial desaturation. Subsequently, desaturated blood enters the systemic circulation. This condition sometimes coexists with other congenital heart defects, such as patent ductus arteriosus and atrial septal defect.
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Overview-Causes
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Exact cause unknown Possibly multifactorial
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Overview-Risk Factors
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Poor maternal nutrition Viral illness such as maternal rubella Advanced maternal age Maternal alcohol use Genetic disorders
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Overview-Incidence
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Tetralogy of Fallot accounts for approximately 7% to 10% of cases of congenital heart disease. It’s the most common cardiac anomaly occurring within the first year of life that requires surgical intervention. Its incidence increases with increased maternal age. It occurs equally in males and females.
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Overview-Complications
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Cerebral abscesses Erythrocytosis from chronic hypoxemia Acute gouty arthritis Delayed puberty Neurodevelopmental impairment Postoperative complications Residual right ventricular outflow obstruction or VSD Chronic pulmonary regurgitation Ventricular and atrial tachyarrhythmias Right bundle branch block Infective bacterial endocarditis Residual right ventricular outflow obstruction or VSD Chronic pulmonary regurgitation Ventricular and atrial tachyarrhythmias Right bundle branch block Infective bacterial endocarditis
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Assessment-History
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Hypercyanotic spells (“tet spells”) Diminished exercise tolerance Increasing dyspnea on exertion Growth retardation or delayed development Eating difficulties
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Assessment-Physical Findings
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Clubbing Cyanosis if severe right ventricular outflow tract obstruction is present (otherwise acyanotic) Dyspnea on exertion Squatting position after exertion or during tet spells Single S2 heart sound Loud, harsh, crescendo-decrescendo systolic heart murmur (best heard along the left sternal border), which may diminish or obscure the pulmonic component of S2 Cardiac thrill at the left sternal border and an obvious right ventricular impulse Early systolic ejection sound Crescendo-decrescendo systolic ejection murmur (due to flow across the narrowed right ventricular outflow tract) Prominent inferior sternum
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Diagnostic Test Results-Laboratory
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Arterial oxygen saturation is diminished in patients with this disorder. Polycythemia is present in patients with this disorder. Hematocrit may be more than 60%. Platelet count is low. Total fibrinogen level and coagulation factors are diminished. Prothrombin time is prolonged.
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Diagnostic Test Results-Imaging
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Chest X-rays may demonstrate decreased pulmonary vascular marking, depending on the severity of the pulmonary obstruction, a boot-shaped cardiac silhouette, and a prominent right ventricle. Echocardiography identifies septal overriding of the aorta, the VSD, and pulmonary stenosis and detects the hypertrophied walls of the right ventricle. Magnetic resonance imaging identifies structures and provides information about intracardiac pressures and blood flow. Transthoracic (or transesophageal) echocardiography reveals defects.
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Diagnostic Test Results-Diagnostic Procedures
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An electrocardiogram may show right ventricular hypertrophy, right axis deviation, and, possibly, right atrial hypertrophy. Cardiac catheterization confirms the diagnosis by showing pulmonary stenosis, the VSD, and the overriding aorta and by ruling out other cyanotic heart defects.
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Treatment-General
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Prevention and treatment of complications During tet spells, knee-chest position and administration of oxygen and morphine to improve oxygenation
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Treatment-Activity
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As tolerated and appropriate for age
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Treatment-Medications
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Oxygen Morphine I.V. during severe tet spells
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Treatment-Surgery
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Palliative surgery performed on infants with potentially fatal hypoxic spells, with the goal of surgery being to enhance blood flow to lungs to reduce hypoxia, commonly accomplished by joining the subclavian artery to the pulmonary artery (Blalock-Taussig procedure) Complete intracardiac corrective surgery, which relieves pulmonary stenosis, closes the VSD, and redirects left ventricular outflow to the aorta
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Nursing Considerations-Nursing Diagnoses
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Decreased cardiac output Delayed growth and development Disabled family coping Impaired gas exchange Ineffective peripheral tissue perfusion
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Nursing Considerations-Expected Outcomes
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maintain adequate cardiac output, maintain hemodynamic stability, and experience no arrhythmias demonstrate age-appropriate skills and behaviors to the extent possible agree to seek help from peer support groups or professional counselors to ensure adaptive coping behaviors maintain adequate ventilation and oxygenation maintain adequate peripheral tissue perfusion.
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Nursing Considerations-Nursing Interventions
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Assist the child into the knee-chest position when he is experiencing a tet spell. Administer I.V. morphine as ordered for severe spells. Prepare the patient physically and emotionally for surgery. Allow the patient and family to verbalize fears and anxiety related to the condition and surgery. Provide clear communication and explanations about care and the treatment plan. Provide frequent rest periods; cluster care activities to allow for rest and to minimize energy expenditure and oxygen demand. Maintain a patent airway. Administer oxygen as ordered based on oxygen saturation levels via pulse oximetry or arterial blood gas analysis. Institute continuous cardiac monitoring as indicated to evaluate for arrhythmias. Provide postoperative care, including frequent monitoring and surgical site care. Encourage age-appropriate activities and play.
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Nursing Considerations-Monitoring
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Vital signs Cardiac status, including heart rate and rhythm and heart sounds Tet spells Pulmonary status, including airway, oxygenation, and lung sounds Oxygen saturation levels Fluid balance and hydration Postoperative status Surgical site Coping strategies
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Nursing Considerations-Associated Nursing Procedures
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Arterial pressure monitoring, pediatric Arterial puncture for blood gas analysis, pediatric Blood pressure assessment, pediatric Cardiac monitoring Intake and output assessment Oxygen administration, nasopharyngeal catheter, pediatric Postoperative care Preoperative care, pediatric Preparing a patient for cardiac surgery, OR Pulse assessment, pediatric Pulse oximetry, pediatric Respiration assessment Respiratory assessment, pediatric Temperature assessment Venipuncture, pediatric
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Patient Teaching-General
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disorder, diagnosis, and treatment, including palliative and total corrective surgeries and the high survival rates associated with these surgeries fact that the child will set his own exercise limits and will know when to rest signs and symptoms of tet spells and measures to implement when they occur, such as helping the child into the knee-chest position measures to prevent infective endocarditis and other infections, including the need to practice good dental care and to avoid crowds and people with infections need to be alert for ear, nose, and throat infections and dental caries, all of which require immediate treatment importance of adhering to recommended follow-up care, including postprocedure echocardiography within 1 year age-appropriate activities and toys to foster growth and development.
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Patient Teaching-Discharge Planning
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Refer the child and family to home health care services for additional evaluation and follow-up. Refer the child and family to social services for additional resources and support. Refer the parents to support groups as indicated.

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