– Only some impulses conduct through the AV node (usually every other impulse).
• 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
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).
Atrial Flutter Causes • Severe Mitral Valve Disease, Hyperthyroidism, Pericardial Disease, Primary Myocardial Disease • May occur after Cardiac Surgery, with Acute MI, COPD, and Hypoxia
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
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)
PSVT • Deviation from NSR – The heart rate suddenly speeds up, often triggered by a PAC (not seen here) and the P waves are lost.
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).
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
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
Other treatments • Lidocaine • Amiodarone • Procainamide • Magnesium • Oxygen • ACLS protocol • Defibrillation
Ventricular Arrhythmias • Ventricular Tachycardia • Ventricular Fibrillation
Ventricular Conduction Normal Signal moves rapidly through the ventricles Abnormal Signal moves slowly through the ventricles
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
Ventricular Tachycardia • Deviation from NSR – Impulse is originating in the ventricles (no P waves, wide QRS).
Ventricular Tachycardia •
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