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)
treatment for PVCs?
correct underlying cause, if PVC s occur with bradycardia, correct brady first
what drugs would you consider for PVCs if symptomatic?
amiodarone, lidocaine, procainamide, magnesium, quinidine, and beta blocekrs
what is vtach?
exist when there are 3 or more consecutive PVCs present at a rate of >100/min-250min (usually 150-180). the rhythm may start and stop (non-sustained or paroxysmal) or may persist for a long period of time (sustained).
what other arrhythmias are vtach hard to differentiate from?
SVT with bundle branch blocks (aberration)
on an ECG what should ALWAYS be considered vtach until proven otherwise?
wide QRS
what drug do you NOT GIVE with suspected vtach? and why?
verapamil- can exacerbate v tach
what drugs are given for vtach?
amiodarone, procainamide, or lidocaine
what is tornado de pointes?
(twisting around the baseline), is a form of ventricular tachycardia that occurs where the Q-T interval is prolonged
what drugs induce tornade de pointes?
undone, prcainamide, disopyramide, phenothiazines, tricyclic anti-depressants or can be induced with electrolyte imbalaes such as those occurring with prolonged diuretic therapy
what congenital condition can induce tornado de pointes?
prolonged QT syndrome
what drug would you give to correct tornade de pointes?
mg sulfate
how does tornade de pointe present on an ECG?
vary i shape and are below and above the isoelectric baseline
what are some ECG clues of vTach?
rate 150-180, p waves may be present or retrograde or absent but have no relationship to QRS, rhythm is regular but may vary slightly, QRS width is usually .14 or >, morphologic clues of QRS in V1 and V6
what are some causes of vtach?
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 vtach?
may be asymptomatic if the rate is slower than 110 or if runs are short, usually symptomatic bc of inc rate and sustained, loss of atrial kick, no time for the heart to fill, can be life threatening and deteriorate to pulseless
what are the treatments for vtach?
with pulse and systolic bp approx 90, amiodarone, lidocaine, procainamide, magnesium, electrolyte replacement, possible cardioversion
with bp <90 sedate and cardiovert and no pulse CPR, defibrillate
what is ventricular fib?
a lethal arrhythmia that occurs when there are multiple areas in the ventricles depolarizing and repolarizing with no organized ventricular depolarization. the ventricles fibrillate with no coordinated activity at 300-500/minute resulting in no pulse
what is the treatment for vfib?
defibrillate (only)
how does vfib present on an ECG?
grossly irregular baseline with no normal looking QRS or P waves, may be fine or course (greater or less than 3 mm)
what are the possible causes of vfib?
CAD, cardiomyopathy, CHF, valvular heart disease, prolonged QT interval, increased sympathetic tone, stimulants, electrolyte imbalance, dig toe, and acid/base imbalance
what are the hemodynamic effects of vfib?
may be asymptomatic if rate is slower like 110 or if runs are short but usually symptomatic so loss of atrial kick, no time for heart to fill, can be life threatening and deteriorate to pulseless
what are the treatments for afib?
rapid defibrillator, CPR
what is the number one advanced cardiac life support rule?
wide QRS tacky is v tach until proven otherwise
