Pt 4 Ventricular Dysrhythmias Flashcards
* PVC's * V Tach * Torsades de Pointes * V Fib * Asystole * PEA
- PVC’s
- V Tach
- Torsades
- V fib
- Asystole
- PEA
Ventricular dysrhythmias are potentially more life-threatening than atrial dysrhythmias b/c the __ __ pumps oxygenated blood throughout the body to perfuse vital organs & other tissues
left ventricle
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Is a contraction coming from an ectopic focus in the ventricles
premature ventricular contraction (PVC)
> Is the premature (early) occurrence of a QRS complex
A PVC is wide & distorted in shape compared to a QRS complex coming down the normal conduction pathway
PVCs that arise from different foci appear different in shape from each other & are called multifocal PVCs; PVCs that have the same shape are called unifocal PVCs
When every other beat is a PVC, the rhythm is called __ __
When every third beat is a PVC, it’s called __ __
ventricular bigeminy
ventricular trigeminy
Two consecutive PVCs are called a couplet
__ __ occurs when there are 3 or more consecutive PVCs
Ventricular tachycardia
- R-on-T phenomenon occurs when a PVC falls on the T wave of a preceding beat
- Especially dangerous b/c the PVC is firing during the relative refractory phase of ventricular repolarization
- Excitability of the cardiac cells inc during this time, & risk for PVC to start ventricular tachycardia or ventricular fibrillation is great
- HR varies according to intrinsic rate & # of PVCs
- Rhythm is irregular b/c of premature beats
- P wave is rarely visible & is usually lost in the QRS complex of the PVC
- Retrograde conduction may occur, & the P wave may be seen following the ectopic beat
- P-R interval is not measurable
- QRS complex is wide & distorted, lasts > 0.12 sec
- T wave generally large & opposite in direction to major direction of QRS complex
- Associated w/stimulants, electrolyte imbalances, hypoxia, & heart dz
- Not harmful w/normal heart but CO reduction, angina, & HF in diseased heart
- Assess apical-radial pulse deficit
Treatment
- Correct causes (i.e., oxygen therapy for hypoxia, electrolyte replacement)
- Anti-dysrhythmics
> Beta-adrenergic blockers, procainamide, or amiodarone
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A run of 3 or more PVCs defines __ __
Rate is 150-250 bpm
Rhythm may be regular or irregular
ventricular tachycardia (VT)
- AV dissociation may be present, w/P waves occurring independently of the QRS complex
- Atria may be depolarized by the ventricles in a retrograde fashion
- P wave is usually buried in the QRS complex, and the P-R interval is not measurable
- QRS complex is distorted in appearance & wide (>0.12 sec in duration)
- T wave is in the opposite direction of the QRS complex
- Ectopic foci take over as pacemaker
- Monomorphic, polymorphic, sustained, & non-sustained
- Considered life-threatening b/c of dec CO & the possibility of deterioration to ventricular fibrillation
- VT may be sustained (longer than 30 sec) or non-sustained (<30 sec)
___ VT occurs when the QRS complexes gradually change back & forth from 1 shape, size, & direction to another over a series of beats
Polymorphic VT
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Is a polymorphic VT associated w/a prolonged Q-T interval of the underlying rhythm
! Typically treated w/magnesium sulfate or 150mg amiodarone
Torsades de Pointes
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Is a severe derangement of the heart rhythm characterized on ECG by irregular waveforms of varying shapes & amplitudes
> Represents firing of multiple foci in the ventricle
> Mechanically, the ventricle is “quivering”, w/no effective contraction, & consequently no CO occurs
! Is a lethal dysrhythmia
Ventricular fibrillation
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Represents the total absence of ventricular electrical activity
No ventricular contraction; pt unresponsive, pulseless, apneic
Must assess in more than 1 lead
Asystole
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Is a situation in which organized, electrical activity is seen on the ECG, but there’s no mechanical activity of the ventricles & pt has no pulse
Pulseless Electrical Activity (PEA)
! Prognosis is poor unless the underlying cause is quickly identified & treated
