Tetralogy of Fallot Amogh Kambalyal MDPGY 1 Anatomy

Tetralogy of Fallot Amogh Kambalyal, MD-PGY 1

Anatomy • Classically taught that there are 4 defects of TOF • Some believe in actuality, it is just 1 heart defect and that the other 4 are a result: • Displacement of the infundibular septum from the rest of the interventricular septum • Displaced anteriorly/superiorly/ rightward

Physiology • Hypercyanotic episodes or “Tet Spells” • Muscle bundle near RVOT spasm increased resistance into the pulmonary artery increased deoxygenated blood through VSD into the aorta • Unclear mechanism or trigger • Possibly catecholamine surge • Tet spells seen more in AM, when crying, and seen more in older children

Interventions for Hypercyanotic Episode • Increasing systemic resistance & decreasing pulmonary vascular resistance • Morphine • Fluid bolus • Beta – blocker: relaxes cardiac muscle • Phenylephrine/epinephrine/norepi

• Prostaglandin to keep PDA open • Initial intervention (if needed) Management • Watchful waiting • Only if pulmonary resistance is mild • BT shunt • First palliative operation • Stent • Balloon Angioplasty • Surgical Repair

BT Shunt • Blalock (surgeon) and Taussig (cardiologist) • Considered the First Palliative • Allows for blood flow to the pulmonary circulation • Bypasses the RVOT obstruction • But Pulmonary stenosis worsens with time

• Can stent open the RVOT obstruction

Surgical Repair • 1. Close the VSD • Patch placed to close the VSD • 2. Repair the RVOT obstruction • Break down the muscular obstruction • Infundibular patch or transannular patch to widen the proximal pulmonary artery • Can be done open-heart or percutaneously • Surgical repair usually done electively at 4 -6 months of age

Coronary Artery locations • In TOF, increased propensity for the Left Anterior Descending (LAD) originates from the Right coronary artery • Usually it originates from the Left coronary artery • May impede ability to put RVOT patch • In these pts, may need a conduit