What is the normal duration of the PR interval?

What is the normal duration of the PR interval?

• A. 0.08 to 0.12 seconds
• B. 0.12 to 0.20 seconds
• C. 0.20 to 0.24 seconds
• D. 0.24 to 0.30 seconds

Answer: (B)

The normal duration of the PR interval is between 0.12 to 0.20 seconds. This measurement reflects the time taken for electrical impulses to travel from the atria to the ventricles through the AV node. A PR interval within this range indicates normal conduction of electrical signals in the heart, ensuring that the atria contract and fill the ventricles with blood before the ventricles themselves contract. When the PR interval is shorter than 0.12 seconds, it may suggest a pre-excitation syndrome, where the electrical impulse bypasses the normal conduction pathway. Conversely, a PR interval longer than 0.20 seconds may indicate a conduction delay, such as first-degree heart block, where the electrical signal is delayed as it passes through the AV node. Understanding the significance of the PR interval is essential for assessing various cardiac conditions during ECG interpretation.

The normal duration of the PR interval is between 0.12 to 0.20 seconds. This measurement reflects the time taken for electrical impulses to travel from the atria to the ventricles through the AV node. A PR interval within this range indicates normal conduction of electrical signals in the heart, ensuring that the atria contract and fill the ventricles with blood before the ventricles themselves contract.

When the PR interval is shorter than 0.12 seconds, it may suggest a pre-excitation syndrome, where the electrical impulse bypasses the normal conduction pathway. Conversely, a PR interval longer than 0.20 seconds may indicate a conduction delay, such as first-degree heart block, where the electrical signal is delayed as it passes through the AV node. Understanding the significance of the PR interval is essential for assessing various cardiac conditions during ECG interpretation.