Which agent is most likely to cause tachycardia and should be avoided in patients with LVOT obstruction?

Which agent is most likely to cause tachycardia and should be avoided in patients with LVOT obstruction?

• A. Ketamine
• B. Remifentanil
• C. Pancuronium
• D. Desflurane

Answer: (A)

In LVOT obstruction, keeping heart rate and contractility low while maintaining adequate preload is important because tachycardia and increased contractility worsen the dynamic obstruction and can drop cardiac output. Ketamine provokes a robust sympathetic response, increasing heart rate and blood pressure and boosting contractility. That combination raises the LVOT gradient and can precipitate hemodynamic instability, so ketamine is avoided in these patients. Remifentanil tends to cause bradycardia and hypotension rather than tachycardia; desflurane can cause some tachycardia with airway irritation or rapid changes, but its effect is generally less pronounced than ketamine. Pancuronium can cause mild tachycardia via vagolysis, but ketamine remains the most likely to induce the problematic tachycardia in LVOT obstruction.

In LVOT obstruction, keeping heart rate and contractility low while maintaining adequate preload is important because tachycardia and increased contractility worsen the dynamic obstruction and can drop cardiac output. Ketamine provokes a robust sympathetic response, increasing heart rate and blood pressure and boosting contractility. That combination raises the LVOT gradient and can precipitate hemodynamic instability, so ketamine is avoided in these patients. Remifentanil tends to cause bradycardia and hypotension rather than tachycardia; desflurane can cause some tachycardia with airway irritation or rapid changes, but its effect is generally less pronounced than ketamine. Pancuronium can cause mild tachycardia via vagolysis, but ketamine remains the most likely to induce the problematic tachycardia in LVOT obstruction.