EKG Interpretation: Arrhythmias Humayun J. Chaudhry, D.O., FACP, Humayun J. Chaudhry, D.O., FACP, FACOI FACOI Assistant Dean for Pre-Clinical Assistant Dean for Pre-Clinical Education Education and Chairman, Department of and Chairman, Department of Medicine Medicine N.Y. College of Osteopathic N.Y. College of Osteopathic Medicine Medicine
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EKG Interpretation: Arrhythmias Humayun J. Chaudhry, D.O., FACP, FACOI Assistant Dean for Pre-Clinical Education and Chairman, Department of Medicine N.Y.
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EKG Interpretation: Arrhythmias
Humayun J. Chaudhry, D.O., FACP, Humayun J. Chaudhry, D.O., FACP, FACOIFACOI
Assistant Dean for Pre-Clinical EducationAssistant Dean for Pre-Clinical Education
and Chairman, Department of Medicineand Chairman, Department of Medicine
N.Y. College of Osteopathic MedicineN.Y. College of Osteopathic Medicine
November 18, 2004November 18, 2004
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Arrhythmia
DefinitionDefinition: Any rhythm other than : Any rhythm other than a normal sinus rhythm (NSR)a normal sinus rhythm (NSR)
ManyMany arrhythmias are harmless arrhythmias are harmless SomeSome arrhythmias are life- arrhythmias are life-
threateningthreatening
Analyzing Rhythms
Step 1Step 1: Search for the P waves : Search for the P waves Best seen in the inferior leads or Best seen in the inferior leads or
chest leadschest leads Step 2Step 2: Look at the QRS complex: Look at the QRS complex Step 3Step 3: Look at rate, regularity, : Look at rate, regularity,
configuration and relation of P to configuration and relation of P to QRS to determine the rhythmQRS to determine the rhythm
Pacemaker Sites
SA node typically fires SA node typically fires 60-100 bpm60-100 bpm Junctional area (surrounding the AV Junctional area (surrounding the AV
node) has an intrinsic rate of node) has an intrinsic rate of 40-60 bpm40-60 bpm in adults (junctional escape rhythm)in adults (junctional escape rhythm)
Lower ectopic pacemaker sites have an Lower ectopic pacemaker sites have an even slower intrinsic rate (e.g., even slower intrinsic rate (e.g., ventricular escape rhythm of ventricular escape rhythm of 15-4015-40 bpm)bpm)
Atrial Premature Contractions An ectopic, supraventricular impulse An ectopic, supraventricular impulse
that originates in the atria outside the that originates in the atria outside the SA nodeSA node
Because atrial depolarization does not Because atrial depolarization does not proceed through normal atrial proceed through normal atrial conduction, see a conduction, see a bizarrebizarre or or inverted inverted p p wavewave
Important clueImportant clue: an abnormal or notched : an abnormal or notched T wave preceding an early QRS complexT wave preceding an early QRS complex
Multifocal Atrial Tachycardia An SVT that originates from three An SVT that originates from three
or more different ectopic atrial foci or more different ectopic atrial foci at a rate between 100 and 250 at a rate between 100 and 250 bpmbpm
Seen in patients with COPD and Seen in patients with COPD and acute respiratory distress with acute respiratory distress with resultant hypoxemiaresultant hypoxemia
Paroxysmal Atrial Tachycardia An SVT derived from impulses that follow a An SVT derived from impulses that follow a
re-entry circuit (a closed loop or circular re-entry circuit (a closed loop or circular path through which an impulse path through which an impulse continuously follows itself) in the atria or continuously follows itself) in the atria or AV node areaAV node area
An SVT that originates in the atriaAn SVT that originates in the atria See flutter (F) waves (250-350 See flutter (F) waves (250-350
bpm) that look like a saw-toothbpm) that look like a saw-tooth Rapid, regular rhythmRapid, regular rhythm Determine A:V ratioDetermine A:V ratio
Atrial Fibrillation
An SVT characterized byAn SVT characterized by Absent P wavesAbsent P waves Irregularly irregular R-R intervals Irregularly irregular R-R intervals
with a variable ventricular ratewith a variable ventricular rate Atrial impulses firing at 350-600 Atrial impulses firing at 350-600
bpm bpm See irregular, coarse, or fine See irregular, coarse, or fine
undulations of the EKG baseline undulations of the EKG baseline called fibrillation (f) wavescalled fibrillation (f) waves
Ventricular Premature Contraction An abnormal QRS complex that An abnormal QRS complex that
originates from an ectopic focus in the originates from an ectopic focus in the ventriclesventricles
Depolariation proceeds slowly and Depolariation proceeds slowly and abnormally producing a wide, bizarre abnormally producing a wide, bizarre QRS complex and an abnormal QRS complex and an abnormal ventricular repolarizationventricular repolarization
See a compensatory pause because See a compensatory pause because sinus P wave after the PVC is blockedsinus P wave after the PVC is blocked
Ventricular Tachycardia
A ventricular rhythm of 3 or more PVCs A ventricular rhythm of 3 or more PVCs in a row at a rate faster than 100 bpmin a row at a rate faster than 100 bpm
Wide, bizarre QRS complex in the Wide, bizarre QRS complex in the absence of pre-existing BBB or other absence of pre-existing BBB or other abnormalityabnormality
May be sustained (can degenerate into May be sustained (can degenerate into ventricular fibrillation) or nonsustainedventricular fibrillation) or nonsustained
Most common predisposing cause Most common predisposing cause is prolongation of QT intervalis prolongation of QT interval Acquired (Type I antiarrhythmics, Acquired (Type I antiarrhythmics,