The ECG shows ______ contractions, where extra heartbeats originate from an irritable focus in the ventricles.
1premature✓ 정답
2ectopic
3aberrant
4escape
5retrograde
해설
Premature ventricular contractions (PVCs) occur when the ventricles contract earlier than they should in the cardiac cycle. These early beats originate from an irritable focus in the ventricles rather than following the normal conduction pathway.
1. Premature Ventricular Contractions (PVCs)
- Early beats originating from ventricles
- Wide QRS complex (>120ms)
- No preceding P wave
- Compensatory pause follows
2. Characteristics of PVCs
- Unifocal: single origin point
- Multifocal: multiple origin points
- Bigeminy: alternating normal-PVC pattern
- Trigeminy: two normal beats-one PVC pattern
3. Clinical Significance
- Common in healthy individuals
- May indicate underlying heart disease
- Risk factors: caffeine, stress, electrolyte imbalance
- Treatment needed if frequent/symptomatic
4. Related ECG Terms
- Coupling interval: time between normal and premature beat
- Interpolated PVCs: occur between normal beats
- R-on-T phenomenon: PVC during T wave
- Ventricular tachycardia: multiple consecutive PVCs
핵심 개념
premature — Occurring earlier than normal or expected in the cardiac cycle, specifically referring to contractions that happen before the regular heartbeat sequence
ectopic — Occurring in an abnormal position or place, referring to heartbeats that originate from a location other than the normal pacemaker site
aberrant — Deviating from the normal or typical pattern, referring to abnormal conduction pathways in cardiac electrical activity
escape — A backup heartbeat that occurs when the normal pacemaker fails to initiate a contraction, serving as a protective mechanism
retrograde — Moving or conducted in a backward direction, opposite to the normal direction of cardiac electrical conduction