ECG rhythms Atrial and supraventricular
Atrial fibrillation ECG
Atrial fibrillation with rapid ventricular response. Irregularly irregular RR intervals, no organized P waves — at most a fine, irregular undulation of the baseline — and a ventricular rate above 100/min.
A 30-second recording of the heart model, played in real time. Run live starts the engine itself with this rhythm.
Computed by the TracingsMD heart model (Junkers engine): simulated for education, not a patient recording and not for diagnosis.
Measured on this recording
| Ventricular rate | 119/min |
|---|---|
| PR | Not assessable in this rhythm |
| QRS | 84 ms |
| QT | Not assessable in this rhythm |
| QTc (Bazett) | Not assessable in this rhythm |
| QTc (Fridericia) | Not assessable in this rhythm |
What it is
Disorganized atrial electrical activity with no effective atrial contraction. The AV node is bombarded with very rapid, chaotic atrial impulses and conducts only some of them, so the ventricular response is irregularly irregular; there are no P waves, only a fibrillatory or flat baseline.
How to read this strip
| Rate | Ventricular rate above 100/min. |
|---|---|
| Rhythm | Irregularly irregular. |
| P waves | None; at most a fine, irregular undulating baseline (best seen in the longer pauses). |
| PR | Not measurable. |
| QRS | Narrow. |
| QT | Hard to measure in an irregular rhythm. |
Causes
- Hypertension, heart failure and valvular heart disease (especially mitral).
- Older age, coronary artery disease, smoking.
- Obesity, obstructive sleep apnea, diabetes.
- Alcohol, including binge drinking.
- Hyperthyroidism.
- Acute illness: sepsis, pneumonia, pulmonary embolism, surgery (especially cardiac surgery).
What to consider
- Rapid ventricular response with hypotension, ischemia or acute heart failure is unstable and needs urgent treatment, including synchronized cardioversion, under local protocols.
- A stable rapid response is usually rate-controlled with a beta-blocker or diltiazem/verapamil (avoid the latter with a reduced ejection fraction).
- Estimate stroke risk with a validated score (such as CHA₂DS₂-VASc) and weigh bleeding risk when deciding on anticoagulation.
- AF lasting 48 hours or more, or of unknown duration, needs three weeks of anticoagulation or imaging to exclude atrial thrombus (transesophageal echocardiography) before elective cardioversion, and at least four weeks of anticoagulation afterward; shorter episodes still carry risk when the stroke-risk score is high.
- Look for and treat triggers: infection, thyroid disease, alcohol, electrolyte disturbance.
- A very fast, irregular, wide-QRS AF can be pre-excited (an accessory pathway): AV-nodal blocking drugs (adenosine, beta-blockers, diltiazem, verapamil, digoxin) and IV amiodarone can be harmful; cardioversion or procainamide/ibutilide is used instead.
Key point
Irregularly irregular plus no P waves is AF until proven otherwise; measure the rate over a full 10 s strip because single RR intervals vary.
Not to be confused with
- Multifocal atrial tachycardia (simulator) — MAT has distinct P waves of at least three shapes before the QRS complexes. Here there are no distinct P waves.
- Atrial flutter — Flutter shows regular sawtooth waves and usually a regular ventricular rate. Here the RR intervals vary without a pattern.
- Sinus tachycardia — Sinus tachycardia is regular with a P wave before every QRS.