Basic of ECG and Easy Interpretation
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Transcript of Basic of ECG and Easy Interpretation
BASICS OF ELECTROCARDIOGRAPHY
Dr Mushfiq Newaz Ahmed Medical Officer Department Of Anaesthesia, Comilla Medical College & Hospital
OUTLINE1. Review of the conduction system & Action Potential2. ECG leads and recording 3. ECG waveforms and intervals4. Normal ECG and its variants5. Basic Interpretation Steps of ECG6. Arrhythmia & ECG7. MI & ECG8. EI & ECG9. Thyroid Disorder & ECG10. Emergency ECG
ACTION POTENTIAL OF CARDIAC CELL
BUT THE IRONY OF FATE IS……
WHAT IS AN ECG?
An ECG is the recording (gram) of the electrical activity(electro) generated by the cells of the heart(cardio) that reaches the body surface.
USEFUL IN DIAGNOSIS OF…
Cardiac Arrhythmias Myocardial ischemia and infarction Pericarditis Chamber hypertrophy Electrolyte disturbances
ECG LEADS
ECG LEADSLeads are electrodes which measure the difference in electrical potential between either:
1. Two different points on the body (bipolar leads)
2. One point on the body and a virtual reference point with zero electrical potential, located in
the center of the heart (unipolar leads)
ECG LEADS
The standard ECG has 12 leads: 3 Standard Limb Leads
3 Augmented Limb Leads
6 Precordial Leads
The axis of a particular lead represents the viewpoint from which it looks at the heart
STANDARD LIMB LEADS
EINTHOVEN’S TRIANGLE
PRECORDIAL LEADS
PRECORDIAL LEADS
SUMMARY OF LEADS
Limb Leads Precordial Leads
Bipolar I, II, III(standard limb leads)
-
Unipolar aVR, aVL, aVF (aug-mented limb leads)
V1-V6
ANATOMIC GROUPS(SEPTUM)
ANATOMIC GROUPS(ANTERIOR WALL)
ANATOMIC GROUPS(LATERAL WALL)
ANATOMIC GROUPS(INFERIOR WALL)
ANATOMIC GROUPS(SUMMARY)
Localising the arterial territory
InferiorII, III, aVF
LateralI, AVL, V5-V6
Anterior / SeptalV1-V4
SPECIAL SITUATION Amputation or burns or bandages should be placed
as closely as possible to the standard sites
Dextrocardia right & left arm electrodes should be re-versedpre-cordial leads should be recorded from V1R(V2) to V6
OTHER PRACTICAL POINTS
Effective contact between electrode and skin is essen-tial.
Electrical Artifacts: external or internal-External can be minimized by straightening the lead
wires-Internal can be due to muscle tremors, shivering ,
hiccups
ECG PAPER
ECG PAPER BASICSECG graphs:– Small Square -Height 1 mm and width 0.04 s– Large Square -Height 5 mm and width 0.04X5=0.2s Paper Speed:– 25 mm/s( As 0.2 s=5 mm,1 s=25 mm)Voltage Calibration: – 1 mV= П 10 mm( 10 small square) Half strength 5mm/mV Double strength 20 mm/mV
ECG PAPER BASICS
ECG WAVES
WAVE FORMS
P WAVE Denotes Atrial depolarization Shape-Rounded, neither peaked nor notched Width/Duration-2.5 small sq Height-2.5 small sq Better seen in Lead II/Lead V1 Upright in every lead except aVR May be Biphasic in lead V1(Equal upward and downward
deflection)
PR INTERVAL Distance between onset of P wave to the beginning of Q
wave(in absence of Q wave beginning of R wave) Denotes time interval impulse travelling from SA node to
Ventricular muscle through AV node Normal Range:3 to 5 small Sq Short if ‹3 small sq and long if ›5 small sq
NORMAL QRS COMPLEX Denotes Ventricular depolarization Normal width of QRS-2 to ‹3 small sq Narrow complex if less than 2 small sq and
Broad Complex if more than or equal to 3 small sq
COMPONENT OF QRS COMPLEXo Q wave-width 1 small sq and depth 2 small sq and ‹25%
of following R wave (Pathological if width›1 small sq,depth›2 small sq and
›25% of following R Wave)o R wave height varies, but must remember the thing that
R wave progresses from V1 to V6(2-3 small square to les than 25 small sq/5 large sq)
(Pathological if height›25 small sq/5 large sq)o S wave follow R wave, depth varies,progressively dimin-
ishes from V1 to V6
T WAVE Same direction as the preceding QRS complex Blunt apex with asymmetric limbs Height < 5 small sq in limb leads and <10 small square in
precordial leads Smooth contours May be tall in athletes
ST SEGMENT
Merges smoothly with the proximal limb of the T wave No true horizontality
QT INTERVAL Distance between beginning of QRS to the end Of T
wave Reciprocal relation with heart rate Normal 8-‹11 small sq If arrhythmia is present( HR less than 60 or more than
100 bpm) then QT interval should be corrected. Corrected QT(QTc)=QT/√RR
U WAVE Best seen in midprecordial leads Height < 10% of preceding T wave Isoelectric in lead aVL (useful to measure QTc) Rarely exceeds 1 small sq in amplitude May be tall in athletes (2 small sq)
HEART RATE, RHYTHM AND AXIS
DETERMINING THE HEART RATE
Rule of 300
10 times/20 times method
RULE OF 300Take the number of “Large Square” between neighboring QRS complexes, and divide this into 300. More accuracy can be achieved if the number of “small square” between neighboring QRS complexes divided into 1500
Although fast, this method only works for regular rhythms.
RULE OF 300It may be easiest to memorize the following table:
Number of large square
Rate
1 300
2 150
3 100
4 75
5 60
6 50
7 43
10 TIMES/20 TIMES RULE
Count the number of R in 30 large square(equivalent to 6 second) and multiply it by 10 would become rate in 60 sec. If small strip-counting the number in 15 large square(equivalent to 3 second) and multiply it by 20
This method works well for irregular rhythms.
DETERMINING RHYTHM
AXIS DETERMINATION
The QRS axis represents the net overall direction of the heart’s electrical activity.
Abnormalities of axis can hint at:Ventricular enlargementConduction blocks (i.e. hemiblocks)
THE QRS AXISBy near-consensus, the nor-mal QRS axis is defined as ranging from -30° to +90°.
-30° to -90° is referred to as a left axis deviation (LAD)
+90° to +180° is referred to as a right axis deviation (RAD)
DETERMINING THE AXIS
The Quadrant Method
The Degree Method
THE QUADRANT METHODExamine the QRS complex in lead I/lead aVL and lead III/lead aVF to determine if they are predominantly positive or predominantly negative. The combination should place the axis into one of the 4 quadrants below.
COMMON CAUSES OF LAD May be normal in the elderly and very obese Due to high diaphragm during pregnancy or ascites Inferior wall MI Left Anterior Hemi block Left Bundle Branch Block Emphysema
COMMON CAUSES OF RAD Normal variant Right Ventricular Hypertrophy Anterior MI Right Bundle Branch Block Left Posterior Hemiblock
THE NORMAL ECG & VARIATION WITH RESPIRA-TION
NORMAL SINUS RHYTHM Originates in the sinus node Rate between 60 and 100 beats per min Monomorphic P waves Normal relationship between P and QRS Some sinus arrhythmia is normal
APPROACH TO INTERPRET
STEP-1:LEAD POSITIONNormal-P wave upright in lead I & II and QRS should be
downward in aVR & V1, R wave progresses from V1 to V6(height increases)
Lead Malposition-P wave downward in lead I & II and QRS should be upright in aVR & V1, R wave progresses from V1 to V6(height increases)
Dextrocardia- P wave downward in lead I & II and QRS should be upright in aVR & V1, R wave regresses from V1 to V6(height decreases)
Lead Malposition
Dextrocardia
STEP 2: VOLTAGE OR AMPLITUDE Normal ECG paper- voltage or amplitude 10 mV Half Voltage,5 mV used specially when severe LVH causes very
large QRS complex which merges with QRS complexes of above or below leads
Electrical Alternans-Alternate beat variation in direction, ampli-tude and duration of any component of ECG. It can be found in-Pericardial Effusion, Pericardial Mesothelioma, Pericardial TB, Myocarditis, Hypothermia
STEP 3:RHYTHM & RATE Rhythm Assessment- By Paper & Pencil Method or
Caliper Method
Rate Measurement-By 300 times method/20 times method
STEP 4: AXIS Normal- QRS of lead I(+aVL) and QRS of lead II+(III &
aVF) is in the same direction
LAD- QRS of lead I(+aVL) upward and QRS of lead II+(III & aVF) downward
RAD- QRS of lead I(+aVL) downward and QRS of lead II+(III & aVF) upward
Negative in I, positive in aVF RAD
Positive in I, negative in aVF LAD
STEP 5: BUNDLE BRANCH BLOCK(CLUE: WIDE QRS)
RBBB- M pattern in QRS in Lead V1( or V2/V3). May be nor-mal
LBBB-M pattern in QRS in Lead V6( or V4/V5). T inversion can be found. New onset always Alarming
Bifascicular block- RBBB+ Left posterior Hemiblock----›features of
RBBB+RAD(Ostium Secundum ASD) RBBB+ Left anterior Hemiblock ----›features of
RBBB+LAD(Ostium Primum ASD)
RIGHT MARROW(RBBB) LEFT WILLOW( LBBB)
STEP 6:CHAMBER ENLARGEMENT Right Atrial Enlargement- Tall peaked P wave
Left Atrial Enlargement-Broad/M Pattern/Wide/Bifid or notched P wave
Right Ventricular Enlargement-Tall R in V1 and deep S in V5/V6
Left Ventricular Enlargement-Unusually tall R in V5/V6 and unusually deep S in V1(R+S>35 mm)
RIGHT ATRIAL ENLARGEMENT
LEFT ATRIAL ENLARGEMENT
RIGHT VENTRICULAR HYPERTRO-PHY
RIGHT VENTRICULAR HYPERTRO-PHY
LEFT VENTRICULAR HYPERTRO-PHY
LEFT VENTRICULAR HYPERTRO-PHY
7. WAVE & INTERVAL ABNORMALITY
P WAVE ABNORMALITY Absent- Atrial Fibrillation -Atrial Flutter -Ventricular Tachycardia -SVT -Hyperkalaemia Single for every QRS complex Tall/Peaked-Right Atrial Hypertrophy/Enlargement Wide/Broad/Notched-LA Hypertrophy/Enlargement Multiple-AV Block(Either Partial Or Complete)
Q WAVE ABNORMALITY Pathological Q wave- Old MI - LVH - LBBB -Cardiomyopathy -Emphysema(due to axis change) -Pulmonary Embolism(lead III)
R WAVE ABNORMALITY Tall- LVH(in V5/V6) - RVH(in V1/V2) - True Posterior MI Small-Obesity -Emphysema -Pericardial Effusion -Hypothyroidism -Hypothermia Poor Progression of R wave-COPD -PE(left) -Pneumothorax (left) -Cardiomyopathy -Ant/Anteroseptal MI
QRS COMPLEX ABNORMALITY High Voltage-Thin Chest Wall, Ventricular Hypertrophy Low Voltage-Thick Chest wall, Hypothyroidism, Pericardial Effu-
sion, Emphysema, Hypothermia, Chronic constrictive Pericarditis Wide QRS-BBB -Ventricular Ectopic -VT -Ventricular Enlargement -Hyperkalaemia Narrow QRS-SVT
T WAVE ABNORMALITY Inversion-MI, Ventricular ectopic, Ventricular Hypertro-
phy with strain, Cardiomyopathy, Acute Pericarditis, BBB Tall Peaked-Hyperkalaemia, Hyper acute MI, Acute True
Post. MI Small- Hypokalaemia, Hypothyroidism, Pericardial Effu-
sion
U WAVE ABNORMALITY Inversion- Ischemic Heart Disease -LVH with strain Prominent-Hypokalaemia -Hypercalcemia -Hyperthyroidism
PR INTERVAL ABNORMALITY Prolonged- First Degree Heart Block(Causes- IHD, Acute
Rheumatic Carditis, Myocarditis, Hypokalaemia, Atrial Dilata-tion or Hypertrophy)
Short- WPW syndrome Variable-Second Degree Block( Type I and Type II) -Third Degree Block
ABNORMALITY OF ST SEGMENT
ST ELEVATION PATTERN
PROLONGED QTC (ABCDE) AntiArrythmic-Amiodarone,Flecainide,Disopyramide AntiBiotic-Macrolides AntiC(Psy)cotic-Chlorpromazine, Haloperidol AntiDepressant-TCAEI-Hypokalaemia, Hypomagnaesemia, Hypocalcemia
SHORTENED QT Digitalis effect Hypercalcemia Hyperthermia Vagal stimulation
ARRHYTHMIA & ECG
SINUS BRADYCARDIA
SINUS TACHYCARDIA
HEART BLOCK SA Block
AV Block -1st degree AV block -2nd degree AV block( Type I & Type II) -3rd degree AV block
BBB -RBBB -LBBB
SA BLOCK
Absence of one P-QRS-T complex Pause is multiple of P-P interval(or R-R interval)
IMPORTANT DIFFERENTIAL IS SA AR-REST…
Absence of one P-QRS-T complex Pause is NOT multiple of P-P interval(or R-R interval)
AV BLOCK
RBBB
LBBB
ATRIAL FIBRILLATION
ATRIAL FLUTTER
ATRIAL TACHYCARDIA/SVT
ATRIAL ECTOPIC/PAC
JUNCTIONAL ECTOPIC/PJC
VENTRICULAR ECTOPIC/PVC
MI & ECG
CHANGE IN INJURY, ISCHEMIA & INFARC-TION
RECIPROCAL LEADS
LATERAL MI
ANTEROSEPTAL MI
EXTENSIVE ANTERIOR MI
INFERIOR MI
POSTERIOR MI
ST depression in V2-V3 Tall, Broad R wave in V2-V3 Dominant R wave in V2(R>S) Upright T wave
Posterior MI confirmed by posterior lead V7, V8, V9V7=Left Post. Axillary line, same plane to V6V8=Tip of the scapulaV9=Left Paraspinal line
Same case with posterior leadST segment elevation in V7-V9
DIFFERENCE BETWEEN MI AND ACUTE PERICARDITIS
ST shape-Convex Up Location of ST change-
Territorial Reciprocal ST change-
Present Q wave change-May be
Present
ST shape-Concave up Location of ST change-
Limb & Precordial Reciprocal ST change-Ab-
sent Q wave change-Absent
Acute MI Acute Pericarditis
EI & ECG
HYPOKALEMIA
HYPERKALEMIA
HYPOCALCAEMIA & HYPERCAL-CEMIA
THYROID DISORDER & ECG
HYPOTHYROIDISM
HYPERTHYROIDISM/ THYROTOXICOSIS
EMERGENCY ECG
VENTRICULAR TACHYCARDIA
VENTRICULAR FIBRILLATION
ASYSTOLE
THANK YOU….