Cardiovascular collapse due to high dose of local anesthetic is most likely caused by which mechanism?

Cardiovascular collapse due to high dose of local anesthetic is most likely caused by which mechanism?

• A. Tachyarrhythmias
• B. Myocardial depression
• C. Vasoconstriction
• D. Hypertension

Answer: (B)

High-dose local anesthetics in the bloodstream block cardiac voltage-gated sodium channels, which slows conduction and weakens the heart’s ability to contract. This myocardial depression reduces cardiac output, leading to hypotension and potential cardiovascular collapse. Arrhythmias can occur as part of the toxicity, but the fundamental issue driving collapse is the direct depressive effect on the heart’s conduction and contractile function from Na+ channel blockade. Hypertension or vasoconstriction would not explain collapse in this scenario.

High-dose local anesthetics in the bloodstream block cardiac voltage-gated sodium channels, which slows conduction and weakens the heart’s ability to contract. This myocardial depression reduces cardiac output, leading to hypotension and potential cardiovascular collapse. Arrhythmias can occur as part of the toxicity, but the fundamental issue driving collapse is the direct depressive effect on the heart’s conduction and contractile function from Na+ channel blockade. Hypertension or vasoconstriction would not explain collapse in this scenario.