Anesthesia Knowledge Test 24 (AKT-24) Practice 2026 - Free Anesthesia Practice Questions and Study Guide

Intrathecal anesthetics primarily affect heart rate through their action on the autonomic nervous system. When administered in the subarachnoid space, these anesthetics can block sympathetic nerve fibers, leading to a decrease in sympathetic tone. The sympathetic nervous system is responsible for maintaining heart rate, and its blockade can cause bradycardia, or a decrease in heart rate.

In addition, the reduction in vascular resistance due to sympathetic blockade can lead to changes in blood pressure that may further influence heart rate. The body often compensates for a drop in blood pressure by activating the parasympathetic nervous system, which can also contribute to a decreased heart rate.

While some intrathecal anesthetics might lead to arrhythmias due to various factors, the primary and more common effect is a decrease in heart rate caused by the interruption of sympathetic outflow, making this the most relevant answer in the context of intrathecal anesthesia.