# The ECG demonstrates ______ contractions, where an early beat originates from an irritable focus in the atria.

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> url: https://mymerci.kr/pages/nclex_q.php?qn_id=168410  
> language: ko  
> subject: Diseases of the circulatory system

## 문제

The ECG demonstrates ______ contractions, where an early beat originates from an irritable focus in the atria.

## 보기

1. ectopic **✔ 정답**
2. premature
3. aberrant
4. escape
5. retrograde

**정답: 1**

## 해설

Ectopic contractions, specifically premature atrial contractions (PACs), occur when an irritable focus in the atria fires before the normal sinus node impulse. These early beats originate from a site other than the normal pacemaker, creating an abnormal P wave morphology.

## 임상 시나리오

Key ECG Concepts:

1. Ectopic Beats
- Abnormal cardiac impulses originating outside normal conduction pathway
- Can occur in atria (PACs) or ventricles (PVCs)
- Different P wave morphology from normal sinus rhythm

2. Characteristics of PACs
- Early P wave appearance
- Different P wave shape
- Usually followed by normal QRS complex
- Often has compensatory pause

3. Clinical Significance
- Common in healthy individuals
- May indicate:
* Electrolyte imbalance
* Caffeine excess
* Stress/anxiety
* Underlying heart disease

4. Related Terms
- Atrial ectopic focus
- Supraventricular premature beats
- Atrial extrasystoles
- Premature atrial depolarization

5. ECG Identification
- Premature P wave
- Altered P wave morphology
- Normal PR interval
- Regular QRS complex
- Compensatory or incomplete pause

## 핵심 개념

- **ectopic** — occurring in an abnormal position or place, specifically referring to cardiac activity originating from a location other than the normal pacemaker site
- **premature** — occurring earlier than normal or expected in the cardiac cycle, before the next regular beat is due
- **aberrant** — deviating from the normal or usual course, particularly in reference to abnormal cardiac conduction pathways
- **escape** — a backup rhythm that occurs when the primary pacemaker fails to generate an impulse, protecting against asystole
- **retrograde** — moving or conducted in a direction opposite to the normal flow, particularly referring to electrical impulses traveling backwards through the heart

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