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23 Cards in this Set
- Front
- Back
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Normal Intervals
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PR interval - 0.12-.20 seconds (5 small boxes)
QRS - 0.04-.10 seconds (↑ to 3 small boxes) QT interval ventricular depolarization/repolarization Prolonged with medications |
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How Dysrhythmias Occur
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A disturbance between electrical conductivity & the mechanical response of the myocardium
A disturbance in impulse formation -abnormal rate -ectopic focus A disturbance in impulse conduction -delays and blocks Combination of several mechanisms |
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How Dysrhythmias are Treated
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Oxygen
Medications Cardioversion/defibrillation CPR-pulseless Ablation – laser kills tissue that is causing the dysrrhythmia |
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Cardioversion
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Effective in tachydysrhythmia with a pulse
Atrial tachydysrhythmia Afib w/RVR (rapid ventricular response) SVT (supraventricular tachycardia) Ventricular tachycardia w/pulse Electrical conduction synchronized with the QRS to stop tachydysrhythmia SA node to take back control of rhythm |
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Cardioversion Process
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Start with low joules (50-200j)
Patient must have a pulse Conscious sedation with anesthesia on stand-by Clear all personnel w/patient or bed http://www.youtube.com/watch?v=JJ7sD8CDhqQ&feature=related http://www.youtube.com/watch?v=ReJo4aclOw8&feature=related |
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Defibrillation
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Used with pulseless Vtach & VFib
Electrical shock to stop chaotic asynchronous electrical activity Goal to have SA node regain control Defibrillation Perform CPR until defibrillator ready Charge to 200j, 300j, 360j No sedation needed-patient unconscious Clear all personnel w/patient or bed |
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Defibrillation Safety
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Uses unsynchronized electrical discharge to convert a dysrhythmia (VF or pulseless VT) to a more stable rhythm
Prior to delivering shock, check to be sure that no one is touching the bed Use 25 pounds of pressure if paddles are used Verify the EKG tracing in 2 leads Defibrillator may work on battery |
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Radiofrequency Catheter Ablation
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Performed via cardiac angioplasty
Electrophysiology study to locate the focus Deliver radiofrequency waves to site Destroys irritable focus causing the dysrhythmia |
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Temporary Pacers
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Used for bradydysrhythmias & asystole
Noninvasive (transcutaneous) External pads Uncomfortable due to muscle involvement, skin irritation & diaphoresis Invasive (transvenous) Wire inserted via jugular or subclavian vein Pacing occurs in right ventricle Settings (external pulse generator)) MA (milliamps) Rate Palpate radial or carotid, BP |
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Emergent Medications
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Adenosine
Epinephrine Vasopressin Atropine – know maximum dose for test (3mg) Amiodarone Lidocaine Dopamine Dobutamine Levophed Calcium Magnesium – sometimes used in a code situation Potassium |
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Bradydysrhythmias
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Bradycardia- The SA node discharges impulses more slowly than normal and conduction continues in a normal fashion through the rest of the heart. Check blood pressure.
Atrioventricular Block – all impulses that started in SA node don’t get down in the ventricle Delay in conduction from atria to ventricle First Degree − PR intreval > .20 sec − No symptoms − Identify underlying cause Second Degree, Type I (Wenkebach) − Each beat take longer to conduct until totally block and beat is dropped causing a pause. Second Degree, Type II − PR interval constant but beats are dropped when blocked Complete Heart Block − Atria and ventricles do not communicate − Atrial rate WNL or accelerated − Ventricular rate 40-60 |
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Bradydysrhythmias
Clinical Manifestations |
Syncope
Dizziness & weakness, fatigue Confusion Hypotension Diaphoresis SOB Ventricular ectopy Anginal pain |
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Treatment for Bradycardia
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If the patient is symptomatic (light headed, ↓ BP, ↓ U. O)
Give Atropine IV 0.5mg to 1.0 mg until a maximum of 3.0 mg has been given Consider transcutaneous pacing Dopamine infusion at 5-10 mcg/kg/min Atropine not effective in CHB because it won’t get down to the ventricle |
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Atrial Tachydysrhythmias
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Atrial Fibrillation
Atrial Flutter Supraventricular Tachycardia |
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Atrial Fibrillation
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Acute intermittent or chronic
High RF pulmonary embolism (RA) and embolic stroke (LA) Rapid ventricular response → ↓ cardiac output Treatment − Cardizem – most common − Amiodarone − Anticoagulants − Cardioversion − Radiofrequency Catheter Ablation |
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Supraventricular Tachycardia (SVT)
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Aflutter or SVT
Symptoms RT ventricular response Treatment – most common in adenosine − SVT – adenocard − Cardizem − Corvert (ibutilide) − Cardioversion − Radiofrequency Catheter Ablation |
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Ventricular Dysrhythmias
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Premature ventricular complexes
Ventricular tachycardia Ventricular fibrillation |
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Premature Ventricular Contractions (PVCs)
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An ectopic foci in the ventricles discharges an impulse before the SA node.
Due to: − Hypoxia/acidosis − Electrolyte imbalance − MI − Stimulants |
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Treatment for PVCs
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For frequent PVCs (greater than 6/min, multifocal, runs of PVCs)
Correct underlying cause Give oxygen Amiodarone Electrolyte replacement >5000 PVCs in 24 hr → betablockers Page 741 for drugs to treat PVC’s |
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Ventricular Tachycardia
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Causes
Ischemic heart disease MI Cardiomyopathy ↓ K+, ↓Mg++ Valvular disease Heart failure Drug toxicity Hypotension Ventricular aneurysm |
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Treatment for VT with a pulse
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Stable patient
− Oxygen − Confirm rhythm with 12 lead ECG − Amiodarone 150 mg IV over 10 minutes followed by drip or Lidocaine IV bolus-1.0-1.5mg/kg ,Magnesium − Synchronized Cardioversion if unstable − Oral antidysrhythmics mexiletine (Mexitil) or sotalol (Betapace, Sotacor) |
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Ventricular Fibrillation
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Treatment of VF or pulseless VT
Check for responsiveness, activate the EMS system (call a code), call for a defibrillator Open the airway, check for breathing, begin ventilations, check for pulse, begin compressions As soon as a defibrillator is available-defibrillate at 360 joules CPR for 2 min Check for pulse If pulse is absent and there is no rhythm change-defibrillate at 360 joules Start an IV and begin to administer meds (CPR should be continued) Give epinephrine 1 mg IV push (may give every 3-5 minutes) Defibrillate at 360 joules, continue CPR If patient remains in rhythm, administer Amiodarone 300mg IV followed by an infusion of 1mcg/kg/min OR Lidocaine at 1.0-1.5 mg/kg IV followed by an infusion of Lidocaine at 1-4 mg/min CPR should continue, epinephrine may be give every 3-5 minutes and defibrillation at 360 joules may continue to be attempted |
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Asystole
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cardiac standstill, not electrical activity or pump
Treatment for Asystole - EPINEPHRINE Check for responsiveness, activate EMS (call a code), call for defibrillator Begin CPR Start an IV and administer Epinephrine 1mg IVP (Epinephrine may be repeated every 3-5 minutes) Atropine 1 mg IV (may repeat in 3-5 minutes until a total of 3 mg is given (not recommended by AHA) Consider causes of PEA such as hypovolemia, hypoxia, acidosis, potassium imbalances, hypothermia, overdose, cardiac tamponade, tension pneumothorax, acute coronary syndrome, PE) |
