Rebecca was right. Interspersed among normal beats came fast salvos of wide, slurred shapes. They were a clear indication of V-tach, or ventricular tachycardia, a severe form of heart arrhythmia. Normally, heartbeats appear on electrocardiograms as tight, high spikes. The tightness reflects the efficiency of the heart's electrical conducting system.
Impulses start in the natural pacemaker located high in the heart's right corner.
They spread through the atria, hit the atrioventricular node at the junction of the four chambers, then zip through special electricity-conducting cells to the tips of the ventricles and trigger smooth, coordinated contractions. The wide tracings that show up on an electrocardiogram reflect less efficient conduction through neighboring muscle fibers, as opposed to the fast-acting cells that carry the electrical impulses. When that happens, the ventricle has less time to recover for another contraction, and it beats too weakly to support a decent blood pressure. Left unchecked, V-tach will continue until it exhausts the heart or provokes a lethal, chaotic rhythm called ventricular fibrillation. If that doesn't work, start an IV drip of Pronestyl.