ventricular arrhythmias Flashcards
ventricular arrthymias originate where?
below the branching portion of the HIS bundle in the ventricles
when do ventricular arrhythmias occur?
patients with hypoxia, electrolyte imbalance, dig tox, the “pro-arrhythmic”, effects of drugs (e.g.. quinidine, procainamide, phenothiazines, tricyclic anti-depressants, haldol)
what are the electrophysiologic mechanisms responsible or ventricular arrhythmias?
increased automaticity, re-entry, or triggered acctivity
how does the ECG present for all arrhythmias originating in the ventricles? what occurs
wide QRS (>.10 seconds and usually >.14 seconds)electrical depolarization oes not follow the normal pathway but goes fro cell to cell like dominoes
what are premature ventricular contractions?
extra ventricular contractions originating from an ectopic focus in the ventricles
what are unipolar, unifocal, and monomorphic beats?
if the premature contractions originate from a single focus and are the same shape for each beat?
what are premature contractions that originate from multiple sites of the ventricle called?
multifocal, or polymorphic
in PVCs is the rhythm disturbed or interrupted?
no because the early extra beats are originating in the ventricles, they are not interrupted so there is full compensatory pause (p waves map out and are not re-set)
when would the sinus node be interrupted and re-set in PVCs?
if there is retrograde conduction back up into the atria with the extra ventricular beat and they both depolarize at the same time then it will re-set. the pause will then be incomplete
what is it called when every other beat is a PVC?
bigeminal
what is it called when there is one PVC for every two normal beats?
trigeminal
what is it called when there is paired PVCs?
two PVCs back to back. when there are 3 or more in a row, it is termed vtach (or a run)
what are some ECG clues of PVCs?
early wide QRS complex (usually .12/.14 or >), t wave opposite to underlying rhythm, may have sinus or retrograde p waves ‘lurking’ around but they are not related to the QRS, complete compensatory pause, may be incomplete pause if retrograde atrial depolarization or fusion, morphologic clues of QRS in V1 and V6
what are some causes of PVC?
CAD (ischemia, acute MI, CHF), cardiomyopathy, vascular heart disease, increased sympathetic tone, stimulants, electrolyte imbalance, dig toxicity, acid/base balance
what are some hemodynamic effects of PVCs?
asymptomatic but may be a warning sign of more serious arrhythmias, esp dangerous if falls on t waves, are multifactorial, or are runs, symp usually with frequency (dec SV, CO, BP, lightheadedness)