Saturday, November 13, 2010

Fallot's Tetralogy

Tetralogy of Fallot
    TOF involves four defects within the heart. These are VSD, an overriding aorta (wrongly positioned overtop the ventricular septum), right ventricular hypertrophy, and a partial or complete obstruction of blood flow from the right ventricle (also termed RVOT-right ventricular outflow tract obstruction and most often results from pulmonary stenosis).

1 - pulmonary stenosis (a form of right
ventricular outflow tract obstruction)
2 - right ventricular hypertrophy
3 - overriding aorta
4 - ventricular septal defect
The degree of pulmonary stenosis controls the
flow patterns. The shaded blue arrows show blue
blood mixing with red blood. The broken white
arrows indicate diminished blood flow through
the pulmonary artery.

Cyanotic defect resulting in delivery of  inadequately oxygenated blood. 

Blood enters the right heart normally. RV outflow obstruction causes shunting across the VSD to the aorta thereby mixing systemic venous with oxygenated blood from LV causing cyanosis.

Severity of pulmonary stenosis determines the severity of cyanosis.

Classic hypoxic episodes: Marked increasing cyanosis, hyperpnea, and irritability progressing to unconciousness, seizures, or cardiac arrest.

Dependent on severity of pulmonary stenosis. If severe they will be ductal dependent from neonatal period and require immediate surgery. If not severe symptoms may be mild: dyspnea on exertion, clubbing, squatting, and cyanosis

Systolic ejection murmur at left sternal border.

CXR- Boot shaped heart from absence of PA segment

IV, O2, Monitor.

3cc/kg/hr D10W  for infants under 1 year of age, D5W if over 1 year.

Prostaglandins in the neonate if needed.

Classic hypoxic spells are treated with sedation, volume (Hct 45% or greater), bicarb, O2, knee to chest positioning, and intubation/paralyzation if needed. Morphine is drug of choice to relieve agitation.

Foley catheter insertion to follow renal perfusion and urine output.

ABG to follow acidosis.

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