Implantable cardioverter-defibrillators (ICD) are highly successful in preventing sudden cardiac death from rapid, irregular heart rhythms known as ventricular tachycardia (Vtach). When the heart rhythm goes haywire, the device acts like shock paddles to deliver a jolt that restores normal rhythm. Although patients appreciate the freedom an ICD provides, the shocks can be painful. After an ICD fires, some patients find the anticipation of another shock highly stressful. For these patients, catheter ablation can reduce the number of painful shocks they receive.