PHGY 210 Lecture Notes - Lecture 4: Ventricular Fibrillation, Vagal Tone, Sinus Tachycardia
18 Mar 2017
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Fast & slow ap: ventricular ap is fast, while sa/av node ap is slow, rest of heart fast, everywhere in the heart (muscle), ap is fast, slower upstroke/depolarization and slower propagation of ap (100x slower, 1cm/s vs 1m/s. If only blocked one branch, still see qrs complex: need bilateral block in bundle branches, or av or his, for every two atrial ap, only one goes through to ventricle. Premature ventricular contraction: ectopic focus: generates beats in place where shouldn"t (somewhere other than. Ventricular tachycardia & fibrillation: right after, don"t come back to normal rhythm, repeated and continuous qrs waves, 0. 2 seconds between contraction (5 contractions per sec, bp drops towards 0 since don"t have time for filling, not pumping blood. Isolate the pulmonary veins, put catheter with heat or cold around each vein so that cardiac tissue dies and replaced with scar tissue: pulmonary vein isolation used to treat atrial fibrillation.
