The ECG demonstrates ______ contractions, where an early beat originates from an irritable focus in the atria.
1ectopic✓ 정답
2premature
3aberrant
4escape
5retrograde
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.
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
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