In sustained ventricular tachycardia, there are consecutive impulses that arise from the ventricles at a heart rate of 100 beats or more per minute until stopped by drug treatment or electrical conversion. This condition is very dangerous. It is dangerous because it may degenerate further into a totally disorganized electrical activity known as ventricular fibrillation. In ventricular fibrillation, heart's action is so disorganized that it quivers and does not contract, thus failing to pump blood. Many types of heart disease cause arrhythmia.
Coronary disease is often a trigger.
It triggers arrhythmia because coronary heart disease produces scar tissue in the heart. This scar tissue disrupts the transmission of signals which control the heart rhythm. Some people are born with arrhythmias, meaning the condition is congenital . Atherosclerosis is also a factor in causing arrhythmia. Other medical conditions such as diabetes and high blood pressure also are factors.