ECG Rhythm Evaluation
The rhythm is best analyzed by looking at a rhythm strip. On a 12 lead ECG this is usually a 10 second recording from Lead II. Confirm or corroborate any findings in this lead by checking the other leads. A longer rhythm strip, recorded perhaps recorded at a slower speed, may be helpful. 7 step approach to ECG rhythm analysis 1. Rate Tachycardia or bradycardia? Normal rate is 60-100/min. 2. Pattern of QRS complexes Regular or irregular? If irregular is it regularly irregular or irregularly irregular? 3. QRS morphology Narrow complex: sinus, atrial or junctional origin. Wide complex: ventricular origin, or supraventricular with aberrant conduction. 4. P waves Absent: sinus arrest, atrial fibrillation Present: morphology and PR interval may suggest sinus, atrial, junctional or even retrograde from the ventricles. 5. Relationship between P waves and QRS complexes AV association (may be difficult to distinguish from isorhythmic dissociation) AV dissociation *complete:*atrial and ventricular activity is always independent. incomplete: intermittent capture. 6. Onset and termination Abrupt: suggests re-entrant process. Gradual: suggests increased automaticity. 7. Response to vagal manoeuvres Sinus tachycardia, ectopic atrial tachydysrhythmia: gradual slowing during the vagal manoeuvre, but resumes on cessation. AVNRT or AVRT: abrupt termination or no response. Atrial fibrillation and atrial flutter: gradual slowing during the manoeuvre. VT: no response. Differential Diagnosis Follow links below for examples of individual rhythms. ...