First question: Do you have VT or just a lot of PVCs? If your holter monitoring only revealed PVCs and you don't have serious symptoms, I would try to read a little less about VT and stop scaring yourself - that would probably also reduce the PVCs.
To answer your question; there are differences in the mechanisms of short runs of VT and sustained VT. Short runs of VT are usually caused by an abnormal ventricular "pacemaker" that suddenly decide to fire a salvo of PVCs instead of one (this can be caused by two mechanisms). Sustained VT is almost always caused by a scar on the heart (usually after a heart attack or other damage to the heart) which allows an electrical impulse to travel around the scar, causing a "reentry" ventricular tachycardia which can not "break" the same way a supraventricular tachycardia can, because the AV node is not involved.
VF from VT happens if the rhythm is so fast and inefficient (in VT and PVCs for that matter, the heart is activated "backwards" and not through the normal conduction channels, so the pumping force is greatly reduced - that's why you often notice the PVC as a skipped beat and not a double beat like a PAC) that the heart do not get enough oxygen to keep up the rapid heart rate. Usually, that requires a weakened left heart chamber too (which is sometimes a consequence after a heart attack)
This answer is assuming that you meant monomorphic VT, not polymorphic, which is not the same.
Thank u for all the info , i do tend to scare myself at times from reading articles off the net and reading about various heart studies, etc... I havent had any recorded vt on my holters, just pvcs 12%-17% of overall daily beats worth with only several isolated pacs/svt. So it all seems to be going on in my ventricles. I think the most i ever had for a run of pvcs or pacs (wasnt sure which they were-just felt fluttering/flip flop) was under 10 in a row.
I dont seem to have any other symptoms with these. So to understand its monomorphic vt that can possibly cause vf and polymorphic doesnt? I get worried alot about being to far from a hospital incase i ever get an attack of vt and think i wont make it there in time for treatment. not a fun way to live.
I understand your fears, I have frequent PVCs and I am always worried that it will turn into VT/VF. It is a consuming fear, and each and every ectopic beat causes me to panic. I just wanted to show my support to you, and to let you know that you are not alone, I feel this way too.
If you are having serveral runs of VT I would definitely speak to your doctors about your concerns.
I know some patients with consistent ectopy, as you describe, having permanent defibrilators implanted. They work similar to a pace maker, but rather then pace the heart, they deliver an electrical shock (as they would in the ER) if you heart goes into a lethal rhythm.