Under what condition can ketamine unmask myocardial depressant effects?

Under what condition can ketamine unmask myocardial depressant effects?

• A. Depleted Catecholamine Stores or Sympathectomy
• B. Adequate Catecholamine Stores
• C. Increased Vagal Tone
• D. High Nitric Oxide Levels

Answer: (A)

Ketamine’s cardiovascular effects rely on endogenous catecholamines to boost heart rate, contractility, and blood pressure. When catecholamine stores are depleted or the sympathetic nerves are disrupted (sympathectomy), that supportive drive is lost. Without catecholamines to amplify its action, ketamine’s own direct myocardial effects become evident, leading to depressed contractility and reduced cardiac output. That’s why depleted catecholamine stores or sympathectomy best explains the unmasking of myocardial depressant effects. Adequate catecholamines would preserve the usual stimulatory response; increased vagal tone or high nitric oxide levels do not explain this unmasking mechanism in the same way.

Ketamine’s cardiovascular effects rely on endogenous catecholamines to boost heart rate, contractility, and blood pressure. When catecholamine stores are depleted or the sympathetic nerves are disrupted (sympathectomy), that supportive drive is lost. Without catecholamines to amplify its action, ketamine’s own direct myocardial effects become evident, leading to depressed contractility and reduced cardiac output. That’s why depleted catecholamine stores or sympathectomy best explains the unmasking of myocardial depressant effects. Adequate catecholamines would preserve the usual stimulatory response; increased vagal tone or high nitric oxide levels do not explain this unmasking mechanism in the same way.