What is meant by shockable rhythm?

As a medical professional with expertise in cardiology, I can explain what a "shockable rhythm" means in the context of cardiac arrest and emergency medical treatment. When a patient experiences a sudden cardiac arrest, their heart may stop beating effectively, which is a life-threatening condition. There are different types of heart rhythms that can occur during cardiac arrest, and they are categorized based on whether they are treatable with a defibrillator, a device that delivers an electric shock to the heart. Shockable rhythms are those that can potentially be corrected with a defibrillator. There are two main types of shockable rhythms: 1. Ventricular Fibrillation (VF): This is a chaotic heart rhythm where the heart's ventricles quiver instead of pumping blood effectively. It's one of the most serious types of arrhythmias and requires immediate defibrillation. 2. Pulseless Ventricular Tachycardia (VT): This is a rapid heart rhythm that originates in the ventricles. Although the heart may be pumping, it's not doing so effectively, and the patient has no pulse. VT can sometimes degenerate into VF, which is why it's also considered a shockable rhythm. Defibrillators are programmed to recognize these rhythms and advise the operator to deliver a shock if the rhythm is shockable. Prompt defibrillation is critical because the chances of survival decrease by 7-10% for every minute that passes without it.

The cardiac arrest treatment algorithm divides cardiopulmonary resuscitation into the treatment of shockable rhythms - ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT) (Figure 1); and the treatment of non-shockable rhythms - asystole and pulseless electrical activity (PEA) (Figure 2).