I've had multiple long runs of monomorphic non-sustained ventricular tachycardia. echo & stress test normal. what causes this?

Unknown- LQTS? Bruga: There r many potential causes, especially in a young person like urself. Electrolyte imbalances, stretch of the ventricle (or 1 of the chambers), or a genetic condition like Brugada's syndrome r all possible. I doubt it's related to ischemia or restricted blood flow- u r too young to have atherosclerotic heart disease. But follow the investigational plan laid out by ur doctor & find the cause. GL!

Many possible causes: certainly structural heart disease such as coronary disease or heart muscle disease can cause ventricular tachycardia and in the absence of this electrolyte abnormalities such high or low potassium or magnesium or other conditions such as right ventricular outflow tract navy or brugada syndrome or long QT syndrome or other genetic conditions can cause ventricular tachycardia