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EKG Extravaganza!

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EKG Extravaganza!. Michele Ritter, M.D. Argy Resident – Feb. 2007. Normal Conduction of the Heart. SA node Left/Right atrium Atrial Contraction AV node Bundle of His Purkinjie fibers Endocardium Epicardium Ventricular contraction. Generation of EKG. Generation of EKG. P wave: - PowerPoint PPT Presentation
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EKG Extravaganza! Michele Ritter, M.D. Argy Resident – Feb. 2007
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Page 1: EKG Extravaganza!

EKG Extravaganza!

Michele Ritter, M.D.

Argy Resident – Feb. 2007

Page 2: EKG Extravaganza!

Normal Conduction of the Heart

SA node Left/Right atrium Atrial Contraction AV node Bundle of His Purkinjie fibers Endocardium Epicardium Ventricular

contraction

Page 3: EKG Extravaganza!

Generation of EKG

Page 4: EKG Extravaganza!

Generation of EKG

P wave: = depolarization/contraction of both atria

QRS complex: = depolarization/contraction of ventricles

T wave = rapid phase of ventricular repolarization

ST segment = plateau phase of ventricular repolarization

QT interval = ventricular systole

Page 5: EKG Extravaganza!

ECG Leads

Limb Leads Bipolar

Lead I – left arm (+) and right arm (-)

Lead II – left leg (+) and right arm (-)

Lead III – left leg (+) and right leg (-)

Unipolar aVR -

right arm potentials aVL – left arm

potentials aVF – left leg

potentials

Precordial Leads V1 V2 V3 V4 V5 V6

Page 6: EKG Extravaganza!

Precordial Leads

Page 7: EKG Extravaganza!

Reading EKGs

1. Rate

2. Rhythm

3. Axis

4. Hypertrophy

5. Infarction

Page 8: EKG Extravaganza!

Rate

Large Box = 0.2 seconds Small Box = 0.04 seconds

Page 9: EKG Extravaganza!

Rate

300-150-100-75-60-50 Rule If one box between R-waves, then rate is 300;

If two boxes between, then rate 150, etc. Rate = 1500/(mm between R waves)

Page 10: EKG Extravaganza!

What is the rate?

Page 11: EKG Extravaganza!

Rhythm

Is the rhythm regular (distance between QRS complexes equal)?

Is there a P-wave before every QRS complex?

Is the PR interval normal? 0.12 sec - 0.20 sec

Is the QRS duration normal? 0.04 sec to 0.12 sec

Page 12: EKG Extravaganza!

Irregular Rhythms

Usually caused by multiple, active automaticity sites that causes irregular atrial and ventricular activity

Include: Wandering Pacemaker Multifocal Atrial Tachycardia Atrial Fibrillation

Page 13: EKG Extravaganza!

Irregular Rhythms

Wandering Pacemaker Have P’ waves (not true P waves because

pacemaker activity is wandering from SA node to a nearby atrial automaticity foci)

Atrial Rate less than 100 Irregular shape to P waves and irregular

ventricular rhythm.

Page 14: EKG Extravaganza!

Irregular Rhythms (cont.)

Multifocal Atrial Tachycardia Think of it as tachycardic wandering pacemaker P’ waves again Atrial rate excees 100 Irregular ventricular rhythm Irregular morphology of P’ waves Occurs in:

COPD Heart Disease

Page 15: EKG Extravaganza!

Irregular Rhythm (cont.)

Atrial Fibrillation No P waves (because there are multiple atrial automaticity

foci sending impulses – no single impulse depolarizes atria completely)

Irregular ventricular rhythm Caused by:

Heart disease (CAD, CHF) Thyroid disease Pericardial effusion Alcohol

Page 16: EKG Extravaganza!

Tachy-arrhythmias

Rapid rhythms originating in a very irritable foci that paces rapidly.

Includes:

Rate Range

Paroxysmal Tachycardia 150 to 250

Flutter 250 to 350

Fibrillation 350 to 450

Page 17: EKG Extravaganza!

Atrial Tachyarhythmias

Supraventricular tachycardia Includes paroxysmal junctional tachycardias

Paroxysmal Atrial Tachycardia and Paroxysmal Junctional Tachycardia

Caused by very irritable automaticity foci that originate above the ventricles.

Narrow QRS complex tachycardia Have P’ waves – often get lost in QRS.

Page 18: EKG Extravaganza!

Supraventricular arrhythmias

Page 19: EKG Extravaganza!

Atrial Tachyarrhythmias (cont.)

Torsades de Pointes Rate is usually 250 to 350 beats/min. The amplitude of each successive complex gradually

increases and then gradually decreases – “party streamer”

Caused by: Severe hypokalemia Medications that block potassium channels Congenital abnormality (Long QT syndrome)

Page 20: EKG Extravaganza!

Atrial Tacchyarrhythmia

Atrial Fibrillation Rapid Ventricular Response = increased heart

rate, putting patient at risk for hypotension.

Page 21: EKG Extravaganza!

Atrial Tachyarrhythmias (cont.)

Atrial Flutter Extremely irritable atrial focus produces a

rapid series of atrial depolarizations (250-350 beats/min.)

Page 22: EKG Extravaganza!

Ventricular tacchyarrythmias (cont.)

Paroxysmal Ventricular Tachycardia Is like a run of PVC’s Irritable (hypoxic) ventricular focus results in

rapid rate that is too fast for heart to function effectively.

WIDE QRS COMPLEX tachycardia

Page 23: EKG Extravaganza!

Ventricular Tacchyarhythmia (cont.)

Ventricular Fibrillation Caused by rapid-rate discharges from many irritable,

parasystolic entricular automaticity foci. An erratic, rapid twitching of the ventricles, with

ventricular rate reaching 350 to 450 beats/min. Tracing is totally erratic, without identifiable waves.

Page 24: EKG Extravaganza!

Tacchyarrhythmia Wolff-Parkinson-White syndrome

A ventricular “pre-excitation” arrhythmia An abnormal, accessory AV conduction pathway, the bundle

of Kent, can “short circuit” the usual delay of ventricular conduction in the AV node.

Results in Shortened PR interval (< 0.12 sec) Widened QRS (> 0.12 sec) Delta waves

Can result in several tachyarrhythmias including supraventricular tachycardia, atrial flutter, atrial fibrillation

Page 25: EKG Extravaganza!

Blocks

Sinus Block AV Block Bundle Branch Block

Page 26: EKG Extravaganza!

Sinus Block

SA node fails to pace for at least complete cycle. Occurs in:

Sick Sinus Syndrome (SSS) SA node dysfunction resulting recurrent episodes of

sinus block or sinus arrest Frequently occurs in elderly patients with heart

disease. Bradycardia-Tachycardia Syndrome

Patients with SSS who develop episodes of supraventricular tachycardia mingled with sinus bradycradia.

Page 27: EKG Extravaganza!

AV Block

1° (first degree) AV Block Prolongs AV node conduction Prolonged PR interval (>0.2 sec – one big

box) The PR interval is consistently prolonged the

same amount in every cycle P-QRS-T sequence is normal in every cycle.

Page 28: EKG Extravaganza!

AV Block (cont.)

2° (second degree) AV Block Wenckebach (Mobitz Type I)

Gradually prolongs the PR interval , until the final P wave fails to produce a QRS response.

This cycle then repeats itself. Usually non-pathologic

Mobitz (Mobitz Type II) Totally blocks a number of paced atrial depolarizations (P

waves) before conduction to the ventricles is successful. Can be:

2:1 – two P waves to every QRS 3:1 – three P waves to every QRS

Usually permanent, and can progress to complete heart block

Page 29: EKG Extravaganza!

2° AV Block – “Wenckebach”

Page 30: EKG Extravaganza!

2° AV Block - Mobitz

2:1

3:1

Page 31: EKG Extravaganza!

AV Block - 2° AV block (cont.)

If see 2:1 AV block and uncertain if Wenckebach or Mobitz… Do vagal maneuver If Wenckebach, there is an increase the

number of cycles/series (increasing to 2:3 or 4:3)

If Mobitz (Type II), it becomes a 1:1 AV conduction.

Page 32: EKG Extravaganza!

AV Block (cont.)

3° (third degree) AV block: “Complete Heart Block” Complete block of the conduction to the ventricles, so

atrial depolarizations are not conducted to the ventricles.

See a sinus-paced atrial (P wave) rate and a totally independent, focus-pased, slow ventricular (QRS rate) – AV dissociation.

Can have: Junctional Focus

Normal (narrow) QRS Ventricular rate: 40-60/min.

Ventricular Focus PVC-like QRS’s Ventricular rate: 20-40/min.

Page 33: EKG Extravaganza!

AV Block (cont.)

3° (third degree) AV Block

Page 34: EKG Extravaganza!

Bundle Branch Block

Page 35: EKG Extravaganza!

Bundle Branch Blocks

Caused by block of conduction in the right or left bundle branch.

The bundle branch delays depolarization to the ventricles that it supplies.

Left Bundle Branch Block (LBBB) Associated with cardiovascular disease! Incidence increases greatly with age. Think – V5, V6!!

Right Bundle Branch Block (RBBB) Associated with structural heart disease, increased

age, sometimes iatrogenic (cardiac cath.) Think – V1, V2!!

Page 36: EKG Extravaganza!

Bundle Branch Block

Page 37: EKG Extravaganza!

Left Bundle Branch Block

Widened QRS (> 0.12 sec, or 3 small squares)

Two R waves appear – R and R’ in V5 and V6, and sometimes Lead I, AVL.

Have predominately negative QRS in V1, V2, V3 (reciprocal changes).

Page 38: EKG Extravaganza!

Right Bundle Branch Block

Widened QRS (> 0.12 sec or 3 small squares)

R and R’ in V1V1 and V2, often with ST depression and T wave inversion.

Reciprocal changes (big negative S) in V5,V6, I and AVL.

Page 39: EKG Extravaganza!

Right Bundle Branch Block

Page 40: EKG Extravaganza!

Bundle Branch Block

Final Note: If you have the above changes with R and R’,

but a normal (not widened) QRS, it is referred to as an incomplete bundle branch block.

Page 41: EKG Extravaganza!

Axis

The direction of depolarization as it passes through the heart.

A vector towards a lead results in a positive deflection on the ECG, while a deflection away from a lead results in a negative deflection.

If hypertrophy is present, the overall vector (axis) points towards the hypertrophied part.

Page 42: EKG Extravaganza!

Axis

Frontal Plane Horizontal Plane

Page 43: EKG Extravaganza!

Axis

Normal Axis: QRS vector pointed downard and to the patient’s left, in the 0 to 90° Range.

Right axis Deviation: > 100° Left axis Deviation: < 0°

Page 44: EKG Extravaganza!

Axis – the nitty gritty

QRS net positive in Lead I and AVF: normal axis QRS net positive in Lead I and net negative in AVF: Left axis Deviation QRS net negative in Lead I and net positive in AVF: Right axis Deviation

AVF

Page 45: EKG Extravaganza!

Axis

Left Axis Deviation: Can occur in:

Left Ventricular Hypertrophy (hypertension!) Inferior myocardial infarction

Right Axis Deviation: Can occur in:

Right ventricular overload (cor pulmonale) Left pneumothorax Lateral myocardial infarction.

Page 46: EKG Extravaganza!

Hypertrophy – we’re going to essentials only. Left Ventricular Hypertrophy

Important because it is often a sign of long- standing hypertension!

Calculation: mm of S in V1

+ mm of R in V5 If sum is more than 35 mm, you have LVH!!!

Remember, you usually see Left axis deviation with LVH.

Page 47: EKG Extravaganza!

Now the most important….

MYOCARDIAL

INFARCTION !!!!

Page 48: EKG Extravaganza!

EKG in Myocardial Infarction

Gives information about: Duration — hyperacute/acute versus

evolving/chronic Extent — transmural versus subendocardial Size — amount of myocardium affected Localization (which area of heart affected)

Difficult to use EKG in certain situations: Left bundle branch block Paced rhythm

Page 49: EKG Extravaganza!

EKG in myocardial infarction

Ischemia: T wavesInjury: ST changesNecrosis: Q waves

Page 50: EKG Extravaganza!

Myocardial Ischemia

Represented by inverted T waves. Should be symmetrically inverted. Can be marker of OLD infarction Wellens syndrome: Marked T wave inversion in V2

and V3, which alerts to stenosis of the left anterior descending coronary artery (LAD)

Page 51: EKG Extravaganza!

Myocardial Injury

Injury = “acute” or “recent” ischemia.

ST changes show that the episode is acute.

Transmural injury ST Elevation

Subendocardial injury ST Depression

Page 52: EKG Extravaganza!

ST elevation

Page 53: EKG Extravaganza!

ST depression

Page 54: EKG Extravaganza!

Myocardial Necrosis Q wave:

Diagnostic for myocardial infarction. Can have MI in its absence (non Q-wave MI) Can be acute or old! (Use ST changes to determine if

acute) Is significant if at least one small square (1 mm or 0.4

seconds in duration) Is usually at least 1/3 of the QRS amplitude

Page 55: EKG Extravaganza!

Location of Infarction Posterior

Right Coronary Artery Large R, ST depressions in V1, V2,

V3 Inferior

R or L coronary artery ST changes/Q waves in II, III, AVF May have reciprocal ST depressions

in I and AVL Lateral

Circumflex artery ST changes/Q waves in I and AVL,

V5, V6 May have reciprocal ST depressions

in II, III, AVF. Anterior

Left Anterior Descending artery ST changes/Q wave in V1, V2, V3,

V4

Page 56: EKG Extravaganza!

Where’s the MI?

Page 57: EKG Extravaganza!

Where’s the MI?

Page 58: EKG Extravaganza!

Where’s the MI?

Page 59: EKG Extravaganza!

Final one…

Page 60: EKG Extravaganza!

EKG - Conclusion

1. Rate

2. Rhythm1. Regular, irregular, irregularly irregular?

2. P waves? PR interval? QRS duration?

3. Axis

4. Hypertrophy

5. Ischemic Changes 1. T wave changes?

2. ST changes?

3. Q waves


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