Only some impulses conduct through the AV node usually every other impulse

Only some impulses conduct through the av node

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Only some impulses conduct through the AV node (usually every other impulse).
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Ventricular rhythm: regular versus irregular Ventricular conduction can be regular if the atrial to ventricular conduction ratio is constant or can be irregular if atrial to ventricular conduction is variable; e.g. 3:1, 4:1, 2:1. Atrial rhythm: “F” flutter waves are regular, P waves are NOT present. Atrial rate: 250-350, QRS varies. PR Not measurable QRS < .12
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Atrial Flutter Etiology: Reentrant pathway in the right atrium with every 2nd, 3rd or 4th impulse generating a QRS (others are blocked in the AV node as the node repolarizes).
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Atrial Flutter Causes Severe Mitral Valve Disease, Hyperthyroidism, Pericardial Disease, Primary Myocardial Disease May occur after Cardiac Surgery, with Acute MI, COPD, and Hypoxia
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Treatment Flutter Amiodarone helps to convert to SR and control ventricular response Beta-Blockers, Calcium Channel- Blockers and digoxin control AV node (ventricular response) Depending on Clinical Presentation: Synchronized Cardioversion
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Supraventricular Tachycardia Paroxysmal- rhythm that starts and stops suddenly PAT- sudden burst of 3 or more PAC’s that becomes the rhythm for a short time SVT: PAT that is not self-limiting SVT: includes dysrhythmias originating above the AV node (Sinus Tach, a-fib, a- flutter)
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PSVT Deviation from NSR The heart rate suddenly speeds up, often triggered by a PAC (not seen here) and the P waves are lost.
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PSVT Etiology: There are several types of PSVT but all originate above the ventricles (therefore the QRS is narrow). Most common: abnormal conduction in the AV node (reentrant circuit looping in the AV node).
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SVT Causes Excessive use of alcohol, caffeine, tobacco and other (street drug) stimulants Electrolyte imbalances, hypoxia Seen in the elderly and generally associated with acute cardiorespiratory illness and COPD
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PSVT Treatment Lower the HR First: try Valsalva Maneuver (Bare down) Next: try Carotid Massage (discouraged in the elderly) MD’s Only! Adenosine: stops all electrical activity of the heart (normal conduction pathway resumes) Amiodarone, Calcium Channel Blockers, Beta- Blockers If all else fails: Electrical Cardioversion
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Other treatments Lidocaine Amiodarone Procainamide Magnesium Oxygen ACLS protocol Defibrillation
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Ventricular Arrhythmias Ventricular Tachycardia Ventricular Fibrillation
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Ventricular Conduction Normal Signal moves rapidly through the ventricles Abnormal Signal moves slowly through the ventricles
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Ventricular Cell Problems Ventricular cells can: fire occasionally from 1 or more foci fire continuously from multiple foci fire continuously due to a looping re- entrant circuit Premature Ventricular Contractions (PVCs) Ventricular Fibrillation Ventricular Tachycardia
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Ventricular Tachycardia Deviation from NSR Impulse is originating in the ventricles (no P waves, wide QRS).
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Ventricular Tachycardia
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  • Spring '14
  • Kwiatkowski,MicheleLisa
  • Nursing, Cardiology, Cardiac electrophysiology, Electrical conduction system of the heart, Ventricular fibrillation

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