# The ECG shows a prolonged ______ interval, indicating delayed conduction between the atria and ventricles.

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> url: https://mymerci.kr/pages/nclex_q.php?qn_id=168385  
> language: ko  
> subject: Diseases of the circulatory system

## 문제

The ECG shows a prolonged ______ interval, indicating delayed conduction between the atria and ventricles.

## 보기

1. PR **✔ 정답**
2. QT
3. ST
4. QRS
5. RR

**정답: 1**

## 해설

The PR interval represents the time taken for an electrical impulse to travel from the atria through the AV node to the ventricles. A prolonged PR interval (>200ms) indicates first-degree AV block, showing delayed conduction through the AV node.

## 임상 시나리오

PR interval:
- Normal duration: 120-200ms
- Measured from P wave onset to QRS complex start
- Represents atrial-ventricular conduction time
- Prolonged PR interval (>200ms) = First-degree AV block
- Components: P wave + PR segment
- Clinical significance:
* AV nodal disease
* Digitalis effect
* Increased vagal tone
* Electrolyte imbalances
- Shortened PR interval (

## 핵심 개념

- **PR interval** — The time measured from the beginning of the P wave to the beginning of the QRS complex, representing atrial to ventricular conduction time
- **QT interval** — The time from the start of the QRS complex to the end of the T wave, representing total ventricular depolarization and repolarization
- **ST segment** — The portion of the ECG between the end of the QRS complex and the beginning of the T wave, representing early ventricular repolarization
- **QRS complex** — The combination of three graphical deflections on an ECG representing ventricular depolarization
- **RR interval** — The time between two consecutive R waves in the ECG, representing the duration of a complete cardiac cycle

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