# Annotations in the MIT-BIH Malignant Ventricular Fibrillation Database
All of the annotations contained in the `.atr` files of
this database are rhythm change annotations, and almost all of them
mark changes in cardiac rhythm (a few indicate episodes of noise or
asystole). The table below indicates
how the `aux` strings of these annotations should be
interpreted.
- AFIB: atrial fibrillation
- ASYS: asystole
- B: ventricular bigeminy
- BI: first degree heart block
- HGEA: high grade ventricular ectopic activity
- N or NSR: normal sinus rhythm
- NOD: nodal ("AV junctional") rhythm
- NOISE: noise
- PM: pacemaker (paced rhythm)
- SBR: sinus bradycardia
- SVTA: supraventricular tachyarrhythmia
- VER: ventricular escape rhythm
- VF or VFIB: ventricular fibrillation
- VFL: ventricular flutter
- VT: ventricular tachycardia
In each case, the rhythm change annotations are placed at the
*beginning* of the episode of the indicated rhythm. The
previous rhythm continues during episodes marked by (NOISE; the
noise ends at the time of the next annotation.