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EKG Interpretation: Arrhythmias. Mustafa Salehmohamed, D.O. Assistant Clinical Instructor Department of Medicine N.Y. College of Osteopathic Medicine October 21, 2005. Arrhythmia. Definition : Any rhythm other than a normal sinus rhythm (NSR) Many arrhythmias are harmless
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EKG Interpretation: Arrhythmias Mustafa Salehmohamed, D.O. Assistant Clinical Instructor Department of Medicine N.Y. College of Osteopathic Medicine October 21, 2005
Arrhythmia • Definition: Any rhythm other than a normal sinus rhythm (NSR) • Many arrhythmias are harmless • Some arrhythmias are life-threatening
Analyzing Rhythms • Step 1: Search for the P waves • Best seen in the inferior leads or chest leads • Step 2: Look at the QRS complex • Step 3: Look at rate, regularity, configuration and relation of P to QRS to determine the rhythm
Pacemaker Sites • SA node typically fires 60-100 bpm • Junctional area (surrounding the AV node) has an intrinsic rate of 40-60 bpm in adults (junctional escape rhythm) • Lower ectopic pacemaker sites have an even slower intrinsic rate (e.g., ventricular escape rhythm of 15-40 bpm)
Arrhythmias • Supraventricular • Pacmaker impulses originate above the ventricles (e.g., SA node, atria, AV node, bundle of His) • Hallmark: narrow, normal-appearing QRS complex (some exceptions)
Arrhythmias • Ventricular • Pacemaker impulses originate in the ventricles • Abnormal, slow, random (muscle cell to muscle cell) depolarization produces a wide QRS complex • Hallmark: wide bizarre QRS complex
10 Answer Now The AV Node Junctional Rate is • >100 bpm • 60-100 bpm • 40-60 bpm • 20-40 bpm • < 20 bpm
Atrial Premature Contractions • An ectopic, supraventricular impulse that originates in the atria outside the SA node • Because atrial depolarization does not proceed through normal atrial conduction, see a bizarre or inverted p wave • Important clue: an abnormal or notched T wave preceding an early QRS complex
Multifocal Atrial Tachycardia • An SVT that originates from three or more different ectopic atrial foci at a rate between 100 and 250 bpm • Seen in patients with COPD and acute respiratory distress with resultant hypoxemia
Paroxysmal Atrial Tachycardia • An SVT derived from impulses that follow a re-entry circuit (a closed loop or circular path through which an impulse continuously follows itself) in the atria or AV node area • Starts abruptly, ends abruptly, conducting at 150-250 bpm • Tx: carotid sinus massage, valsalva, diving reflex, calcium blockers, digoxin, ß-blockers
Wolff-Parkinson-White Syndrome (WPW) • One of the pre–excitation arrhythmias • Conduction occurring through an accessory pathway between the atria and the ventricle – called the Bundle of Kent • This causes an early depolarization of the ventricles manifested on an EKG as an initial slurred upstroke of the QRS complex known as a delta (λ) wave • Other EKG findings can include a wide QRS complex, narrow PR interval < 0.12 seconds • Heart rate will be greater than 150 bpm
Atrial Flutter • An SVT that originates in the atria • See flutter (F) waves (250-350 bpm) that look like a saw-tooth • Rapid, regular rhythm • Determine A:V ratio
Atrial Fibrillation • An SVT characterized by • Absent P waves • Irregularly irregular R-R intervals with a variable ventricular rate • Atrial impulses firing at 350-600 bpm • See irregular, coarse, or fine undulations of the EKG baseline called fibrillation (f) waves
Ventricular Premature Contraction • An abnormal QRS complex that originates from an ectopic focus in the ventricles • Depolariation proceeds slowly and abnormally producing a wide, bizarre QRS complex and an abnormal ventricular repolarization • See a compensatory pause because sinus P wave after the PVC is blocked
Ventricular Tachycardia • A ventricular rhythm of 3 or more PVCs in a row at a rate faster than 100 bpm • Wide, bizarre QRS complex in the absence of pre-existing BBB or other abnormality • May be sustained (can degenerate into ventricular fibrillation) or nonsustained • Tx: drugs, synchronized cardioversion, surgery, catheter ablation
Torsade de Pointes • Most common predisposing cause is prolongation of QT interval • Acquired (Type I antiarrhythmics, psychotropic drugs, low magnesium, low potassium, low calcium, liquid protein diets) • Congenital