**Core Concept**
Local anesthetics (LAs) can cause systemic toxicity when absorbed in high concentrations, leading to central nervous system (CNS) and cardiovascular complications. This occurs due to the accumulation of the uncharged base form of the local anesthetic in the bloodstream, which can cross the blood-brain barrier and interfere with normal neuronal function.

**Why the Correct Answer is Right**
Local anesthetic systemic toxicity (LAST) is characterized by a range of symptoms, including CNS effects such as tinnitus, visual disturbances, and seizures, as well as cardiovascular effects like hypertension, bradycardia, and eventually cardiac arrest. The mechanism of LAST involves the inhibition of sodium channels in the brain and heart, leading to a decrease in the threshold for action potential and an increase in neuronal excitability. The uncharged base form of LAs, such as lidocaine and bupivacaine, is more lipid-soluble and can cross the blood-brain barrier and bind to sodium channels, causing toxicity.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct complication of LA toxicity. Local anesthetic systemic toxicity can cause a range of complications, including CNS effects, cardiovascular effects, and respiratory depression.

**Option B:** This option is incorrect because it is a potential complication of LA toxicity, but not the correct answer. Local anesthetic systemic toxicity can cause seizures, but this is not the exception.

**Option C:** This option is incorrect because it is a potential complication of LA toxicity, but not the correct answer. Local anesthetic systemic toxicity can cause cardiac arrest, but this is not the exception.

**Clinical Pearl / High-Yield Fact**
A key clinical pearl to remember is that the treatment of LAST involves the administration of intravenous lipid emulsion (ILE), which can help to bind and neutralize the uncharged base form of LAs and reduce their toxicity.

**Correct Answer: D.**