Tetralogy of Fallot
(post-op complications)

• Occurs in 10-15% of CHD
• Most common cyanotic defect
• Clinical presentation varies with degree of pulmonic stenosis

1. Pulmonary stenosis -> decreased pulm circulation, murmur decreases as PS increases; in extreme TOF with pulm atresia, pulm blood flow is maintained by a PDA (which is closing) so keep the PDA open with Prostaglandin E infusion.
2. RVH -> RV and LV can be though of as a single chamber
3. VSD -> barely a murmur. As PS increases, R->L shunt increases
4. overriding aortic arch

Really, only 2 are needed:

1. RV outflow stenosis
2. VSD large enough so that LV pressure = RV pressure = Aortic pressure

Murmurs: PS, single S2, loud systolic murmur at upper and middle LSB VSD
EKG: RVH, RAD
History: exertional dyspnea, squatting
May be pink (acyanotic) TOF or cyanotic, depending on degree of pulmonary stenosis, although pink tets may become cyanotic with time, usually by age 1-2.

• Pink tet: mild PS allows left to right shunt across VSD; although usually become cyanotic and have exertional dyspnea with time usually by age 1-2 y.o.
• “Blue tet” –severe PS results in right to left shunt across VSD and decreased pulmonary blood flow

CXR: RVH; boot-shaped heart secondary to concave MPA segment; right aortic arch in 25%

Qp / Qs (pulmonary flow/systemic flow) is related to PS and systemic vascular resistance. R->L shunting increases (Qp/Qs decreases) IF Pulmonary vascular resistance increases (although it is typically fairly constant) or SVR decreases (affected by crying, defecating, activity, tachycardia)

Hypoxic spell = hyperpnea, worse cyanosis, decreased heart murmur

How to stop a hypoxic spell? slow HR and widen the RV outflow tract via: B-blocker, volume expander, increase SVR

• knee-chest position (squat): traps systemic venous blood in legs thereby increasing SVR. Place the baby on the mother's shoulder with the knees tucked up underneath. This provides a calming effect, reduces systemic venous return, and increases SVR.
• MSO4 - depresses respiration, decreases hyperpnea. 0.1-0.2 mg/kg IM/SC (weight/5), may reduce the ventilatory drive and decrease systemic venous return.
• NaHCO3 - corrects acidosis; which may reduce the respiratory center stimulating effect of acidosis.
  Oxygen is of limited value since the primary abnormality is reduced pulmonary blood flow, but can use blow by O2
• vasoconstrictors - phenylephrine 0.02 mg/kg IV (weight/50), is used to increase SVR.
• ketamine - increases SVR, sedation
• propranolol

TAPVR (5 letters) Total anomalous pulmonary venous return
Tetralogy of Fallot (tetra=4)
Transposition of the Great Arteries (2 arteries)
Tricuspid Atresia (tri=3)
Truncus Arteriosus (1 trunk)

CHLA Board Review 2005
 Park MK. Pediatric Cardiology for Practictioners, 3rded. St. Louis,
   Mosby, 1996.