**Question:** Brugada syndrome is associated with

A. Sodium channelopathies
B. Calcium channelopathies
C. Lidocaine sensitivity
D. Beta-blocker sensitivity

**Correct Answer:** B. Calcium channelopathies

**Core Concept:**
Brugada syndrome is a cardiac disorder characterized by a specific ECG pattern (Brugada pattern) and an increased risk of sudden cardiac death. It is a type of arrhythmogenic right ventricular cardiomyopathy. The underlying pathophysiology involves electrical abnormalities in the heart, mainly due to mutations in genes encoding cardiac sodium or calcium channels. These mutations lead to impaired ion channel function, causing the characteristic ECG findings and arrhythmias seen in Brugada syndrome.

**Why the Correct Answer is Right:**
Calcium channels are essential for the proper functioning of cardiac myocytes, particularly during the phase 0 of the action potential (sodium channel blockade). Calcium ions play a crucial role in the contraction and relaxation of cardiac muscle cells. Mutations in genes encoding calcium channels (e.g., CACNA1C) can lead to impaired calcium channel function, which is the case in Brugada syndrome. This results in the characteristic ECG findings (right bundle branch block, ST elevation in V1-V3 leads) and an increased risk of ventricular arrhythmias, including life-threatening ventricular fibrillation.

**Why Each Wrong Option is Incorrect:**

A. Sodium channelopathies: Although sodium channels are involved in the initiation of the action potential in the heart, mutations in genes encoding sodium channels are not directly associated with the ECG findings or arrhythmias seen in Brugada syndrome.

C. Lidocaine sensitivity: Lidocaine is a class Ic antiarrhythmic agent that blocks sodium channels, causing a similar ECG pattern in some patients. However, this option is incorrect as it does not address the genetic basis of Brugada syndrome.

D. Beta-blocker sensitivity: Beta-blockers are known to induce the Brugada pattern in some patients due to their sodium channel blocking effects. However, this option is incorrect as it does not accurately describe the genetic basis of Brugada syndrome.

**Clinical Pearl:**
Brugada syndrome is a genetically determined disorder. In cases where patients demonstrate a type I ECG pattern, it is essential to avoid administering beta-blockers, as they may provoke life-threatening arrhythmias. Instead, consider using class Ic antiarrhythmic agents like ajmaline or flecainide to induce the ECG pattern for diagnostic purposes.