For a 1-year-old with tetralogy of Fallot requiring elective surgery, which anesthetic would provide the most stable hemodynamics?

For a 1-year-old with tetralogy of Fallot requiring elective surgery, which anesthetic would provide the most stable hemodynamics?

• A. Sevoflurane with nitrous oxide
• B. Isoflurane with nitrous oxide
• C. Desflurane with oxygen
• D. Ketamine

Answer: (D)

In tetralogy of Fallot, the anesthesia goal is to minimize right-to-left shunting by keeping systemic vascular resistance (SVR from the systemic side) intact and avoiding increases in pulmonary vascular resistance. If SVR drops or PVR rises, more deoxygenated blood shunts from right to left, worsening oxygenation. Volatile anesthetics and nitrous oxide tend to cause vasodilation and can depress cardiac function, which lowers SVR and can worsen the shunt. Nitrous oxide can also subtly increase PVR in some cyanotic conditions, further compromising oxygenation. Ketamine is the best choice because it preserves or even increases SVR and heart rate through its sympathetic stimulant effects, maintaining blood pressure and cardiac output. This helps keep the balance toward left-to-right flow or, at least, reduces the burden of the right-to-left shunt, providing more stable oxygen delivery. It also tends to preserve spontaneous respiration and myocardial contractility, contributing to hemodynamic stability in a fragile infant with TOF. The other options carry a greater risk of hemodynamic instability in this setting due to vasodilation, potential myocardial depression, and possible shifts that worsen the intracardiac shunt, making them less ideal for maintaining stable hemodynamics during anesthesia.

In tetralogy of Fallot, the anesthesia goal is to minimize right-to-left shunting by keeping systemic vascular resistance (SVR from the systemic side) intact and avoiding increases in pulmonary vascular resistance. If SVR drops or PVR rises, more deoxygenated blood shunts from right to left, worsening oxygenation. Volatile anesthetics and nitrous oxide tend to cause vasodilation and can depress cardiac function, which lowers SVR and can worsen the shunt. Nitrous oxide can also subtly increase PVR in some cyanotic conditions, further compromising oxygenation.

Ketamine is the best choice because it preserves or even increases SVR and heart rate through its sympathetic stimulant effects, maintaining blood pressure and cardiac output. This helps keep the balance toward left-to-right flow or, at least, reduces the burden of the right-to-left shunt, providing more stable oxygen delivery. It also tends to preserve spontaneous respiration and myocardial contractility, contributing to hemodynamic stability in a fragile infant with TOF.

The other options carry a greater risk of hemodynamic instability in this setting due to vasodilation, potential myocardial depression, and possible shifts that worsen the intracardiac shunt, making them less ideal for maintaining stable hemodynamics during anesthesia.