ecg for final part 2 whh

ECG for Final Part II

WHH

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Topics will be covered• ECG basics• How to identify normal ECG• How to identify abnormal findings in ECG

– Atrial hypertrophy - Hyperkalaemia– Atrial fibrillation - Hypokalaemia– Atrial flutter- Pericarditis– Heart blocks– Chambers enlargement– IHD– AMI

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Topics will not be covered• Signs and symptoms of the diseases with

abnormal ECG • Treatments of those diseases

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What is ECG?• ECG is a medical device capable of

recording the electrical activity of the heart from electrodes placed on the skin in specific locations.

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Standard ECG leads• Limb leads

Bipolar limb leads – I, II, IIIUnipolar limb leads – aVL, aVR, aVF

• Chest leadsV1 - V6

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Right Arm

Right Leg

Left Leg

Left Arm

• Limb leads are typically placed on the inside of the wrists and ankles

• To help reduce artifacts you can use the upper arms and thighs

• Do not place limb leads on the torso

Limb leads

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Chest Leads look at the heart in Chest Leads look at the heart in a horizontal plane.a horizontal plane.

• V1: right sternal edge (4th)V1: right sternal edge (4th)• V2: Left sternal edge (4th)V2: Left sternal edge (4th)• V4: the patient’s apex V4: the patient’s apex

beatbeat• V3: half-way b/t V2 and V4V3: half-way b/t V2 and V4• V5: anterior axillary lineV5: anterior axillary line• V6: mid-axillary lineV6: mid-axillary lineV5 and V6 are in the same V5 and V6 are in the same

horizontal plane as V4horizontal plane as V4ChestLeads

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Interpretation of an ECGPatient identificationStandardization1.Rate2.Rhythm3.Axis4.P wave5.PR interval6.QRS complex7.ST segment8.T wave9.U wave10.QT interval

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Conduction system of heart

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Wave. Interval. Complex.• One letter = wave

– Eg = P, T• Need to check height and width

• Two letters = interval– PR interval

• Need to check length

• 3 letters = complex– QRS complex

• Need to check height, width and shape

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• Name• Age • ID number• DOB• Father’s name

Patient identification and standardization

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• Regular RhythmRate = 300÷numbers of large square

• Irregular RhythmNumbers of R in 6 sec x 10 (6s method)

Rate determination

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Regular Rhythm

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Irregular Rhythm

Using 6-sec ECG rhythm strip to calculate heart rate: 7×10 = 70 bpm.

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P wave• Atrial depolarization• Best seen at Lead II• Normal Height <2 ⅟2 small square Width <2 ⅟2 small square

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Atrial Fibrillation• P wave (-)• Fibrillatory wave (+)

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Atrial Flutter• Cavo-tricuspid focus• Saw tooth appearance

Atrial Ventricle Wave HR

1 1 300

2 1 150

3 1 100

4 1 75HEXAGON

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P wave

P pulmonale = RAH

P mitrale = LAH

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PR interval• Conduction time

• Normal0.12-0.2 s (2 – 5 small square)

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AV blocks

Conduction from atrium to the ventricles via

the AV node may be either

– Delayed – as in 1st degree block (or)

– Blocked – as in 2nd and 3rd degree blocks

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– 1st degree HB

– 2nd degree HB

Mobitz type 1 (Wenkebach phenomenon)

Mobitz type 2

– 3rd degree HB (complete HB)

Different types of Heart Blocks

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1st Degree HB• Prolong PR interval only

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2nd degree HB• Mobitz type 1(Wenckebach Block)Progressive Increase PR f/b dropped beat

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2nd degree HB• Mobitz type 2Normal PR f/b dropped beat

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Mobitz Type 2 AV Block

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3rd Degree HB• AV dissociation• PR - Variable• PP - Equal or multiple of interval• RR – Equal• QRS is bizarre

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3rd Degree HB

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3rd Degree HB• 3rd Degree HB or Complete HB

• Does it really matters???

YESIt’s emergency condition

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3rd Degree HB• Adam Stokes attack• Due to Transient ventricular asystole• Cardiac Output decreased to zero

Syncope

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QRS complex• Ventricle depolarization

• Normal0.1s ( 2-2⅟2 small square)

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QRS nomenclature• If 1st deflection is negative Q wave• 1st positive deflection = R wave• Negative deflection after R wave =S wave• Positive deflection after R wave = R prime(R’)• Negative deflection after S wave=S prime (S’)

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AXIS DETERMINATION

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Left axis deviation – positive QRS in lead I

Right axis deviation - positive QRS in lead aVF

Rule of Thumb

AVF

AVF

I

I

CAUSES: LAD

• LVH• And others

Always Abnormal

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CAUSES: RAD

• RVH• And others

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Ventricle hypertrophy• Left ventricle hypertrophy• Right ventricle hypertrophy

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Chest-lead voltage criteria: – S in V1 or V2 + R in V5 or V6 > 35 mm(7.1sq)– R in V5 or V6 >25 mm (5.1sq)

Feature of LVH

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Note

The deep S waves in V1 and tall R waves in V5

and V6.

S V1 + R V5 > 35 mm

Left ventricular strain pattern in V5 and V6

Left ventricular hypertrophy

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• Right axis deviation• R wave larger than S wave in V1

(Tall R in V1)• S wave larger than R wave in V6

(Deep S in V6)

Feature of RVH

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Right Ventricular Hypertrophy

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ST segment• Ventricle repolarization

• ST- isoelectric

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Causes of ST depression• Angina

• NSTEMI

• LVH

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ST depression

• A – upward may be normal• B – down sloping strain / digoxin effect• C – planar ischaemia***

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Angina Pectoris• Imbalance between myocardial oxygen

demand and supply• ST depression and/or T inversion

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Causes of ST elevation

• AMI

• Pericarditis

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Acute Myocardial Infarction• Hyper acute T • ST elevation – myocardial injury• T inversion – myocardial injury• Q wave – myocardial necrosis

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Q wave• NormalLateral leads (I,aVL,V5,V6)III alone mb present1:1:4 =Physiological Q(height <1 ssq, width < 1ssq,Q <1/4 R)

-Old MI

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Standard ECG leads• Limb leads

Bipolar limb leads – I, II, IIIUnipolar limb leads – aVL, aVR, aVF

• Chest leadsV1 - V6

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Infarction Leads

Inferior II,III,aVF

Lateral I,aVL,V5,V6

Septal V1,V2

Anterior V1-V4

Localizing the Infarct

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Inferior Infarction

• Right coronary artery

• Leads II, III, aVF

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Inferior Infarction

I II III aVR aVL aVF V1 V2 V3 V4 V5 V6

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Lateral Infarction

• Left circumflex artery

• I, aVL, V5, V6

• Usually associated with another infarction

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Lateral Infarction


Left circumflex artery

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Anterior Infarction

• Left anterior descending artery

• V2-V4

• V1-V4 = antero-septal infarction

• V1-V6 = extensive anterior infarction

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Anterior Infarction


LADA

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Pericarditis

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T wave• Normal1/8 R < T < 2/3 R

• Tall T– Peak T wave (> 50% of preceding R)– Hyperkalaemia(Tall T , Small P, Wide QRS)

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U wave• Slow repolarization of papillary muscle

• Normal – V1, V2

• Prominent U wave – hypokalaemia

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Interpretation of an ECGPatient identificationStandardization1.Rate2.Rhythm3.Axis4.P wave5.PR interval6.QRS complex7.ST segment8.T wave9.U wave10.QT interval

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P wave : Duration: 0.08 sec ( 2 small squares ) Height: < 2.5 mm ( 2 small squares )

PR interval: Duration: 0.12 - 0.20 sec (3-5 small squares)

QRS Complex : Duration: 0.07–0.10 sec(2 – 2½ small squares)

ST segment : Isoelectric

T wave : 1/8 previous R < T < 2/3 previous R

Important intervals and durations

QUIZ TIME

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THIS IS NOT THE END

This only a beginning and certainly not the end

We look forward for more learning experiences

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ecg for final part 2 whh

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