What happens to the R-R interval in a second-degree Type 1 heart block?

What happens to the R-R interval in a second-degree Type 1 heart block?

• A. It remains constant
• B. It gets longer
• C. It gets shorter
• D. It becomes irregular

Answer: (B)

In a second-degree Type 1 heart block, also known as Mobitz Type I or Wenckebach, the R-R interval exhibits a characteristic change. Specifically, the R-R interval gradually gets longer with each successive beat until a QRS complex is dropped. This progressive lengthening occurs due to the elongation of the PR interval until the electrical impulses are unable to conduct through the AV node leading to a missed beat. This pattern of lengthening reinforces the diagnosis of a second-degree Type 1 block, as it distinguishes it from other types of heart blocks where the R-R interval does not follow this specific pattern. Understanding this progression is key when interpreting an electrocardiogram in a clinical setting.

In a second-degree Type 1 heart block, also known as Mobitz Type I or Wenckebach, the R-R interval exhibits a characteristic change. Specifically, the R-R interval gradually gets longer with each successive beat until a QRS complex is dropped. This progressive lengthening occurs due to the elongation of the PR interval until the electrical impulses are unable to conduct through the AV node leading to a missed beat.

This pattern of lengthening reinforces the diagnosis of a second-degree Type 1 block, as it distinguishes it from other types of heart blocks where the R-R interval does not follow this specific pattern. Understanding this progression is key when interpreting an electrocardiogram in a clinical setting.