Although operative repair of tetralogy of Fallot is definitive, medical therapy can be used to manage hypoxic or tet spells. Tet spells cause acute hypoxia and may be treated with beta blockers, morphine, phenylephrine, and oxygen.

Tet spells cause acute hypoxia and may be treated with:^[1][2][3]

• Beta-blockers such as propranolol or esmolol. The beta-blockers causes relaxation of the right ventricular outflow tract and increases blood flow into the pulmonary vessels.
• Morphine to reduce ventilatory drive
• Phenylephrine to increase systemic afterload that in turn increases the flow across right ventricle and the pulmonary artery and decreases right to left shunting.
• Procedures such as the knee-chest position which increases aortic wave reflection, increasing pressure on the left side of the heart, decreasing the right-to-left shunt thus decreasing the amount of deoxygenated blood entering the systemic circulation.
• Oxygen is ineffective in treating hypoxic spells as the underlying problem is lack of blood flow through the pulmonary circuit and not alveolar oxygenation.
• In case all these measures fail, an emergency Blalock-Taussig shunt might be needed.

• Prostaglandins can be administered while awaiting surgery to maintain patency of the ductus arteriosus.

• Antibiotic prophylaxis is suggested to prevent infective endocarditis, particularly in the repaired tetralogy of Fallot patient with a patch.

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