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

Today is

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1.1. MondayMonday

2.2. TuesdayTuesday

3.3. WednesdayWednesday

4.4. ThursdayThursday

5.5. FridayFriday

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)

Arrhythmias

SupraventricularSupraventricular Pacemaker impulses originate Pacemaker impulses originate

above the ventricles (e.g., SA above the ventricles (e.g., SA node, atria, AV node, bundle of node, atria, AV node, bundle of His)His)

Hallmark: narrow, normal-Hallmark: narrow, normal-appearing QRS complex (some appearing QRS complex (some exceptions)exceptions)

Arrhythmias

VentricularVentricular Pacemaker impulses originate in Pacemaker impulses originate in

the ventriclesthe ventricles Abnormal, slow, random (muscle Abnormal, slow, random (muscle

cell to muscle cell) depolarization cell to muscle cell) depolarization produces a wide QRS complexproduces a wide QRS complex

Hallmark: wide bizarre QRS Hallmark: wide bizarre QRS complexcomplex

The AV Node Junctional Rate is

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1.1. >100 bpm>100 bpm

2.2. 60-100 bpm60-100 bpm

3.3. 40-60 bpm40-60 bpm

4.4. 20-40 bpm20-40 bpm

5.5. < 20 bpm< 20 bpm

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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

Starts abruptly, ends abruptly, conducting Starts abruptly, ends abruptly, conducting at 150-250 bpmat 150-250 bpm

Tx: carotid sinus massage, valsalva, diving Tx: carotid sinus massage, valsalva, diving reflex, calcium blockers, digoxin, reflex, calcium blockers, digoxin, ßß--blockersblockers

Atrial Flutter

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

Tx: drugs, synchronized cardioversion, Tx: drugs, synchronized cardioversion, surgery, catheter ablationsurgery, catheter ablation

Torsade de Pointes

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,

psychotropic drugs, low psychotropic drugs, low magnesium, low potassium, low magnesium, low potassium, low calcium, liquid protein diets)calcium, liquid protein diets)

CongenitalCongenital

What is the heart rate in the Day 6, EKG 6 12-lead tracing?

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1.1. 350 bpm350 bpm

2.2. 250 bpm250 bpm

3.3. 98 bpm98 bpm

4.4. 82 bpm82 bpm

5.5. 68 bpm68 bpm

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What is the mean QRS axis in the Day 6, EKG 6 12-lead tracing?

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1.1. 30 degrees30 degrees

2.2. 60 degrees60 degrees

3.3. 90 degrees90 degrees

4.4. 120 degrees120 degrees

5.5. 150 degrees150 degrees

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What is the rhythm depicted in Day 6, EKG 6 12-lead tracing?

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1.1. Normal sinus rhythmNormal sinus rhythm

2.2. Atrial flutterAtrial flutter

3.3. Atrial fibrillationAtrial fibrillation

4.4. Ventricular flutterVentricular flutter

5.5. Ventricular tachycardiaVentricular tachycardia

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What is the A:V conduction rate in the Day 6, EKG 6 12-lead tracing?

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1.1. 1:11:1

2.2. 2:12:1

3.3. 3:13:1

4.4. 4:14:1

5.5. 5:15:1

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What is the heart rate in the Day 6, EKG 10 12-lead tracing?

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1.1. 100 bpm100 bpm

2.2. 110 bpm110 bpm

3.3. 120 bpm120 bpm

4.4. 130 bpm130 bpm

5.5. 140 bpm140 bpm

What is the mean QRS axis in the Day 6, EKG 10 12-lead tracing?

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1.1. -60 degrees-60 degrees

2.2. -30 degrees-30 degrees

3.3. 0 degrees0 degrees

4.4. 30 degrees30 degrees

5.5. 60 degrees60 degrees

What is the rhythm depicted in the Day 6, EKG 10 12-lead tracing?

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1.1. Normal sinus rhythmNormal sinus rhythm

2.2. Supraventricular tachycardiaSupraventricular tachycardia

3.3. Ventricular tachycardiaVentricular tachycardia

4.4. Atrial flutterAtrial flutter

5.5. Sinus tachycardiaSinus tachycardia