Which of the following is a goal in the management of hypercyanotic spells in tetralogy of Fallot?

Which of the following is a goal in the management of hypercyanotic spells in tetralogy of Fallot?

• A. Increase heart rate
• B. Increase systemic vascular resistance
• C. Increase preload
• D. Decrease systemic vascular resistance

Answer: (B)

Hypercyanotic spells in tetralogy of Fallot happen when the right-to-left shunt across the VSD worsens due to infundibular (RV outflow tract) spasm and reduced pulmonary blood flow. The best goal in management is to raise systemic vascular resistance. Increasing afterload on the left ventricle makes left-sided pressures rise relative to the right ventricle, which diminishes the right-to-left flow across the VSD and skews more blood toward the pulmonary circulation, improving oxygen delivery. Clinically this is achieved with knee-chest or similar postures to boost venous return and afterload, IV fluids to preload the heart, and vasoconstrictors like phenylephrine. While other measures like calming the child or optimizing preload can help, the central aim is increasing systemic vascular resistance to reduce the shunt and improve oxygenation.

Hypercyanotic spells in tetralogy of Fallot happen when the right-to-left shunt across the VSD worsens due to infundibular (RV outflow tract) spasm and reduced pulmonary blood flow. The best goal in management is to raise systemic vascular resistance. Increasing afterload on the left ventricle makes left-sided pressures rise relative to the right ventricle, which diminishes the right-to-left flow across the VSD and skews more blood toward the pulmonary circulation, improving oxygen delivery. Clinically this is achieved with knee-chest or similar postures to boost venous return and afterload, IV fluids to preload the heart, and vasoconstrictors like phenylephrine. While other measures like calming the child or optimizing preload can help, the central aim is increasing systemic vascular resistance to reduce the shunt and improve oxygenation.