A 12-lead ECG can reveal conduction abnormalities such as which of the following?

A 12-lead ECG can reveal conduction abnormalities such as which of the following?

• A. Branches of conduction system blocked
• B. Entire electrical flow is slightly off kilter
• C. Metabolic or chemical abnormalities
• D. All of the above

Answer: (D)

Think of the 12-lead ECG as a multi-angle map of the heart’s electrical activity. It can show blocks in the conduction system when impulses slow or stop in a pathway, producing distinct QRS patterns that help identify which pathway is affected (for example, a bundle branch block). It can reveal the overall direction of ventricular activation, or the electrical axis, shifting when conduction or heart structure changes, which shows up as left or right axis deviation across the leads. It can also reflect metabolic or chemical abnormalities that alter the heart’s resting membrane potential and conduction velocity, producing characteristic ECG changes due to electrolyte disturbances or drug effects that modify depolarization and repolarization. Because a 12-lead ECG can detect these different manifestations, it can reveal a broad range of conduction abnormalities, so all of the listed possibilities can be seen on the test.