Cardiac arrest

American College of Cardiology/American Heart Association/Heart Rhythm Society classification of ventricular arrhythmias[64]Al-Khatib SM, Stevenson WG, Ackerman MJ, et al. 2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Circulation. 2018 Sep 25;138(13):e272-391. https://www.ahajournals.org/doi/pdf/10.1161/CIR.0000000000000549 http://www.ncbi.nlm.nih.gov/pubmed/29084731?tool=bestpractice.com

1. Ventricular tachycardia (VT): ≥3 consecutive complexes originating in the ventricles at a rate >100 bpm. Sustained VT lasts >30 seconds or results in haemodynamic compromise.

2. Monomorphic VT: VT with a stable single QRS morphology from beat to beat.

3. Polymorphic VT: VT with a changing QRS morphology from beat to beat.

4. Torsades de pointes: VT in setting of a prolonged QT interval, with waxing and waning of QRS amplitude.

5. Ventricular fibrillation: rapid, grossly irregular electrical activity with marked variability in waveform; ventricular rate usually >300 bpm (cycle length <200 milliseconds).