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Dysrhythmias (79-150)

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cdunbar4's version from 2016-11-19 18:59

PVCs

Question Answer
PVCpremature ventricular contractions (vent irritability) originating in the ectopic focus of the ventricles
ECG of PVCpremature occurrence of a wide and distorted QRS complex
Types of PVC'smultifocal (cells firing from 2 different places); unifocal (same PVC, firing from one cell); ventricular bigeminy (every other beat); ventricular trigeminy, couples, triplets and R & T phenomena
Clinical associationsstimulants; dig; electrolyte imbalances; hypoxia; fever; disease states: MI, mitral valve prolapse; HF; CAD
Clinical significancein normal heart, usually benign; in HD PVCs may ↓ CO & precipitate angina & HF: pt's response to PVC's must be monitored, PVCS usu don't generate a sufficient vent. contraction resulting in a peripheral pulse, apical-radial pulse rate should be assessed to determine if pulse deficit exists
PVC VT can be stable or unstable, what does this mean?Pt either has a pulse or does not
Sustained VT: severe decrease in CO results in hypoTN; pulm edema; decreased cerebral blood flow; cardiopulm arrest
Complication of PVC if not treated rapidly?vfib; the more irritable the cells, the less organized they become
May occur afterlysis of a coronary artery clot with thrombolytic therapy in acute MI or plaque reduction (a sick heart=> irritable cells in ventricles)
Treatment PVCbased on cause; O2; electrolyte replacement; drugs
Drugs for PVCsBB's; procainmide (antiarrhythmic); amiodarone (antiarrythmic for VT's and SVTs); Lidocaine is used less now (antiarrythmic that exerts effects on nerve axon Na channel prev. depolarization)
Pwave on PVC EKGNo P wave preceding the premature QRS
PR Interval on EKGNot measurable
QRS complexWide (0.12 or greater); also is early and abnormal
Rate and RhythmRate depends on the underlying rhythm of PVC (multifocal, etc.); rhythm irregular
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Vtach

Question Answer
By definition...run of 3 or more PVCs in a row; could turn to Vfib if not treated
Typesmonomorphic, polymorphic, sustained and nonsustained
When should you shock/cpr?If there is a pulse, do NOT shock (there is some CO); No pulse start CPR ASAP, then ACLS/Defib
P WaveNone
PR IntervalNot measurable
QRS complexWide 0.12 or greater
Rate and RhythmRate 100-250; Regular Rhythm (usually)
Types of Drugs used to treat"CAINES" BB's, lidocaine, amiodarone, procainamide or sotalol
Monomorphic; Polymorphic VtachQRS all look the same; Polymorphic aka Toursades de pointes is more serious and unstable
Clinical associations (scarring and stretching of cells)MI, CAD, electrolyte imbalances, cardiomyopathy, mitral valve prolapse, Long QT syndrome, dig tox, CNS disorders
Cardioversion is usedif drug therapy is ineffective
IF CPR and rapid defib is unsuccessful, what can be administered to try to stimulate sympathetic activity?Epinephrine
Difference b/t chemical cardioversion and electrical and cv?Used for Vtach WITH pulse: use drugs 1st to calm them down, then you may considered cardioversion→ hit heart with electrical impulse (but not on the T Wave)
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Vfib

Question Answer
Definitionsevere derangement of the heart rhythm characterized on ECG by irregular undulations of varying contour and amplitude "JELLO" → NO effective contraction/CO/organziation occurs
Clinical associations (same as others, scarring/stretching), can also occur during what procedures?cardiac pacing or catheterization; coronary reperfusion after fibrinolytic therapy
Clinical significance and treatmentUnresponsive, pulseless & apneic state; if not treated then death. IMMEDIATE CPR & ACLS, DEFIB etc.
P waveNone
PR intervalNot measurable
QRS complexNot well defined
Rate and RhythmRate 0 (No pulse); Rhythm irregular (chaotic wavy line)
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Asystole

Question Answer
DefinitionTotal absence of ventricular electrical activity; NO vent. contraction (CO) occurs because depolarization doesn't occur
Clinical associationsadvanced heart disease, severe cardiac conduction system disturbed; ESHF
Clinical sig.unresponsive, pulseless and apneic state; prognosis is extremely poor
Treatment1st try to get some sort of electrical activity THEN→CPR with initiation of ACLS measures (e.g. intubation, transcutaneuous pacing and IV therapy with epi and atropine)
P waves, PR, QRSabsent/measurable
Rate and rhythmNone, nearly flat line
what is defibrillation?passage of DC (direct current) electrical shock through the heart to depolarize the myocardium cells to allow the SA node to resume the role of pacemaker
Recommended energy for initial shocks in defib?150-360 joules; after initial shock CPR should be started
What is synchronized cardioversion?choice of therapy for hemodynamically unstable ventricular or SV tachydysrhythmias
How does synchronized cardioversion deliver a shock?delivers a countershock on the R wave of the QRS complex of the ECG
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ICDs:Pacemakers:Ischemia:Infarct

Question Answer
ICDs are appropriate for what kind of pts?survived SCD; have spontaneous sustained VT; have syncope with inducible ventricular tachy/fib during EPS; are at high risk for future life-threatening dysrhythmias
ICD stans forImplantable Cardioverter-Defibrillator
It's battery-powered, implanted sub Q via which vein?Lead system placed via subclavian vein to the endocadium
ICD sensing system monitors the heart ____ and ______ and id's _____ ______ or _____ _____rate and rhythm; vtach or vfib
Approx. how many seconds after detecting VT or VF, ICD delivers <_________ joules?23 seconds; < or equal to 25 joules shock is delivered; if unsuccessful, ICD recycles and delivers successive shocks
ICDs are equipped with anti_________ and anti_________ pacemakerstachy/brady; initiates overdrive pacing of SVT and VT's; provides backup pacing for bradydysrhythmias that can occur after defib discharges
Educationfear of body image change/recurrent dysrhythmias; expectation of pain with ICD discharge; anxiety about going home; maybe support group should be encouraged
Education: what to avoid, care, what to reportreport s/s infection at incision; keep dry for 4d after surgery; avoid lifting arm on ICD side above shoulder until PCP allows; avoid driving until cleared by PCP; avoid direct blows to ICD site; do not have an MRI; walk through antitheft devices in doorways at a normal pace; if ICD fires more than once, contact EMS; wear Medic Alert/ID card with current list of meds; caregivers learn CPR; air travel is not restricted
Pacemakers are used whenused to pace the heart when the normal conduction pathway is damaged or diseased; initially indicated for SYMPTOMATIC bradydysrhythmias
Demand PacemakerDemand pacemaker for sinus brady, it's set at 72bpm, when SA nodes goes below set value it overrides SA node (INTERMITTENT)
How do pacemakers work?power source with one or more conducting leads & the myocardium; elec. stimulus travels from the pacemaker→through the leads→to the wall of the myocardium→myocardium is "captured" and stimulated
Continuous pacemakereg 3rd degree heart block; it's always on, if battery dies, people die!
Significance of pacemaker ECG?there is a pacemaker "spike" before the QRS and is with EVERY SINGLE BEAT.
Overdrive pacingatrial tachycardias: terminates atrial tachys
Temporary pacemakerstransvenous; epicardial; transcutaneous (pacing ventricles via power source outside of body)
CRTsCardiac Resynchronization Therapy: pacing technique that resynchronizes the cardiac cycle by pacing both ventricles
ECG changes associated with Acute Coronary Syndrome (aka MI): ISCHEMIAO2 demand exceeds supply (aka angina) ST segment depression and/or T wave inversion
When is ST segment depression significant of ischemia?When it is at least 1mm below isoelectric line
Ischemia vs. infarctISCHEMIA: angina (lack of O2, demand exceeds supply results in anaerobic metabolism, can do for awhile w/o damage). INFARCT: necrosis/damage to myocardial cells
Syncopebrief lapse in consciousness accompanied by a loss in postural tone (fainting)
CV causes of Syncopeneurocardiogenic syncope or "vasovagal" syncope; primary cardiac dysrhythmias
Ischemia vs. infarct on ECGISCHEMIA: ST segment depression 1mm below isoelectric line and/or T wave inversion; INFARCT: physiologic Q Wave, ST segment elevation (tombstone) can have T wave inversion
Noncardiovascular causes of syncopehypoglycemia, hysteria, seizure, vertebrobasilar transient ischemic attack
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