Questions?

Any procedures that cause vagal stinulation. facal Impaction removal, Pulling a groin sheath. Sitting up quickly and holding ones breath.

As for prolong QT.. there are loads of durgs that cause this. Google prolong QT syndrome and you will get loads of suggestions

I know of at least 3 different vagal maneuvers---Valsalva maneuver (hold breath and bear down as if to have a BM), carotid massage, and full face immersion in cold water. i have also seen a patient go into asystole after choking on a pill, which an electrophysiologist attributed to vagal stimulation. Vagal maneuvers should only be done if a patient is on a monitor and a crash cart is handy. Kids, don't try this at home!

The only procedure that I can think of to slow a heart rate is to use a pacemaker to overdrive pace and then slow down the rate.

As for QT prolongation, that list is huge. Many drug classes, including antidepressants, antipsychotics, antibiotics, methadone, etc. Check out this link: http://www.azcert.org/medical-pros/drug-lists/bycategory.cfm#