Esnips.com/user/ma7moud
1 Thirty Papers’ ECG – Ma7moud Sho3eb
Thirty Papers’
ECG
Edition st 1 – Part st 1
Esnips.com/user/ma7moud
2 Thirty Papers’ ECG – Ma7moud Sho3eb
بسم اهللا
احلمد هللا على توفيقه وامتنانه، وعظيم نعمه، وتتابع إِحسانه، وأَشهد أَن ال إِله إِال اهللا وحده ال شريك
ورسوله، اللهم صل وسلم عليه وعلى آله وأَصحابه ومن تبعهم بإحسان إىل يوم له، وأَشهد أَن حممداً عبده
. لقائه
العماد : هـ إىل 596 كتب القاضي الفاضل البيساين عبد الرحيم املتوىف سنة فقد : أما بعد
: األصفهاين، معتذراً عن كالم استدركه عليه
وذلك أنين رأيت أنه ال يكتب إنسان كتاباً ، ه إنه وقع يل شىء، وما أدري أوقع لك أم ال، وها أنا أخربك ب ( : يف يومه إال قال يف غده
هذا املكان لكان أحسن لو غري
لو زيد هذا لكان يستحسن
قدم هذا لكان أفضل ولو
. ولو ترك هذا لكان أمجل
. انتهى ) وهذا من أعظم العرب، وهو دليل على استيالء النقص على مجلة البشر
Esnips.com/user/ma7moud
3 Thirty Papers’ ECG – Ma7moud Sho3eb
.:: CONTENTS ::.
BEING FAMILIAR WITH ECG: 1. ‘PQRST’ terminology. 2. The intervals. 3. The leads.
BASIC KNOWLEDGE: 4. Calculation of the Heart Rate. 5. Axis deviation.
DISEASE INTERPRETATION: 6. Atrial hypertrophy. 7. Ventricular hypertrophy. 8. Bundle Branch Block 9. Myocardial infarction
Esnips.com/user/ma7moud
4 Thirty Papers’ ECG – Ma7moud Sho3eb
.:: ABBREVIATIONS ::.
ECG
• An electrocardiogram (ECG) is a recording of the electrical activity of the heart over time produced by an electrocardiograph, usually in a noninvasive recording via skin electrodes.
• Its name is made of different parts: 1.Electro, because it is related to electrical activity. 2.Cardio, Greek for heart. 3.Gram, a Greek root meaning "to write".
aVR Augmented Voltage of Right arm.
aVF Augmented Voltage of Foot.
aVL Augmented Voltage of Left arm.
Lt Left
Rt Right
RV Left Ventricle
LV Right Ventricle
SV1 S‐wave in chest lead 1.
RV6 R‐wave in chest lead 6.
RV1 R‐wave in chest lead 1.
SV6 S‐wave in chest lead 6.
LA Left Arm
RA Right Arm
LL Left Leg
RL Right Leg
Esnips.com/user/ma7moud
5 Thirty Papers’ ECG – Ma7moud Sho3eb
«« The wiring diagram of the heart »»
«« Calibration of the ECG recording »»
• A standard signal of 1 millivolt (mV) should move the stylus 1 vertically 1 cm (2 large squares).
• This ‘calibration’ signal should be included with every record.
Esnips.com/user/ma7moud
6 Thirty Papers’ ECG – Ma7moud Sho3eb
«« A good record of a normal ECG »»
• The upper three traces show the 6 limb leads (I, II, III, VR, VL & VF) and then the six chest leads.
• The bottom trace is a 'rhythm strip' 2 , recorded from lead II (i.e. no lead changes).
• The trace is clear, with P waves, QRS complexes and T waves are visible in all leads.
Esnips.com/user/ma7moud
7 Thirty Papers’ ECG – Ma7moud Sho3eb
‘PQRST’ TERMINOLOGY 3
P‐wave
Represen
ts De‐polarization & contraction of the aria.
QRS‐complex 4 De‐polarization & contraction of the ventricles.
T‐wave Re‐polarization of the ventricles.
Ø N.B.: 1.The Repolarization of the atria is not recorded on the routine ECG. 2.The Repolarization ismuch slower than the depolarization, so the T‐wave is broader than the QRS complex.
3.The Q‐wavemay or may not be present. 4.There may be a small upright deflection following T‐wave & is called U‐wave.
Esnips.com/user/ma7moud
8 Thirty Papers’ ECG – Ma7moud Sho3eb
5.There may be a second upright deflection following R–wave & is called R’‐wave.
6.If a downward deflection occurs after R’, it is called S’‐wave.
«« SOME FORMS OF ‘QRS’ COMPLEXES »»
Ø R‐S patterns:
o Small R‐wave & deep S‐wave. o Tall R‐wave & deep S‐wave. o Tall R‐wave & small S‐wave.
Ø R pattern: o With no Q‐wave or S‐wave.
Ø QS‐ complex: o No R‐wave.
Ø R‐R’ pattern:
Ø R‐S‐R’: Ø R‐S‐R’:With tall R’‐wave. Ø R‐R’‐S’ pattern:
Esnips.com/user/ma7moud
9 Thirty Papers’ ECG – Ma7moud Sho3eb
«« Depolarization & the shape of the QRS complex »»
• The ECG machine is arranges so that: When a depolarization wave spreads towards a lead → the stylus moves upwards. When it spreads away from the lead → the stylus moves downwards.
• Depolarization: (a)Moving towards the lead → a predominantly upward QRS complex. (b)Moving away from the lead → a predominantly downward QRS complex. (c) At right angles to the lead → equal R and S waves.
Esnips.com/user/ma7moud
10 Thirty Papers’ ECG – Ma7moud Sho3eb
THE INTERVALS
P‐R interval 5
Represen
ts The conduction time from the atrium to the ventricles.
QRS interval The time taken by the impulse to spread to the 2 ventricles.
Q‐T interval The total electrical activity of the ventricles.
R‐R interval Is related to the HR or the rate of ventricular contractions.
P‐P interval Indicates the rate of atrial contractions.
Ø N.B.: 1.Under normal circumstances, the R‐R interval & the P‐P interval are equal. 2.In a normal ECG, the P‐R & S‐T segments are at the same horizontal level.
Esnips.com/user/ma7moud
11 Thirty Papers’ ECG – Ma7moud Sho3eb
THE LEADS 6
Ø Limb leads (Leads I, II, III, aVR, aVF & aVL) give different views of the electrical activity of the heart in the frontal plane.
Ø Chest leads give different views in the horizontal plane.
v 3 bi‐polar leads: (I, II & III) 7
v 3 uni‐polar limb leads: (aVR, aVF & aVL)
«« The cardiac axis & lead angles »» 8
Esnips.com/user/ma7moud
12 Thirty Papers’ ECG – Ma7moud Sho3eb
«« The ECG patterns recorded by the 6 ‘standard’ leads »»
v 6 uni‐polar chest leads: (from V1‐6)
«« The relationship between the 6 V leads & the heart »»
Esnips.com/user/ma7moud
13 Thirty Papers’ ECG – Ma7moud Sho3eb
V1 & V2
Faces
The right ventricle.
V3 The inter‐ventricular septum.
V4, V5 & V6 The left ventricle.
• Lead I & aVL are anterior leads directed to the anterior & left wall of the LV. • Lead II, III & aVF are inferior wall leads directed to the inferior wall of the LV.
• Lead I, aVL, V5 & V6 are left sided leads (look at the left side of the heart).
• V1 & V2 are right sided leads (look at the right side of the heart).
Esnips.com/user/ma7moud
14 Thirty Papers’ ECG – Ma7moud Sho3eb
CALCUTAION OF THE HEART RATE
BASIC KNOWLEDGE
• Small square = 0.04 seconds (40 m.sec) of time & 1mm of amplitude.
• Large square = 0.2 seconds (200 m.sec) of time & 5mm of amplitude.
v In case of regular rhythm:
Ø Rate = 1500 ÷ N (N= number of small squares between 2 successive R waves).
• Normal R‐R interval = 15‐25 small squares = 60‐100/min.
• The R‐R interval actually measures the ventricular rate.
• Rates above 100/min→ tachycardia.
• Rates below 60/min→ bradycardia
v In case of irregular rhythm:
Ø Rate = 20 X Number of R waves in 15 large squares (represent 3 seconds).
v In total HB:
• The P‐waves do not correspond with the QRS complexes.
• The atrial rate should be calculated separately: Ø Atrial rate = 1500 ÷ number of small squares between 2 successive P‐waves.
Esnips.com/user/ma7moud
15 Thirty Papers’ ECG – Ma7moud Sho3eb
AXIS
DEVI
ATIO
N Note:
lead
s I &
III
Normal axis 9
Lt axis deviation Rt axis deviation
A mnemonic to remember
Left Leaves Right Reaches
Esnips.com/user/ma7moud
16 Thirty Papers’ ECG – Ma7moud Sho3eb
ATRIAL HYPERTROPHY
Note: the contour of P‐wave, seen best in lead II (also in leads III & aVF)
BASIC KNOWLEDGE
• The P‐wave has 2 components: 1.The initial (1 st ) part is contributed by the Rt atrium. 2.The later (2 nd ) part is contributed by the Lt atrium.
Lt atrial hypertrophy Rt atrial hypertrophy
o The 2 nd component is delayed & prominent → wide & notched P‐wave (wider than 2.5 small squares).
o Since this is common in MV diseases, it is called P mitrale.
o The 1st component is prominent → tall & peaked P‐wave (taller than 2.5 small squares).
o Since this is common with PH, it is called P pulmonale.
o Bi‐atrial hypertrophy:
o The P‐wave iswider than 2.5 small squares & taller than 2.5 small squares.
Esnips.com/user/ma7moud
17 Thirty Papers’ ECG – Ma7moud Sho3eb
«« Lt atrial hypertrophy »»
«« Rt atrial hypertrophy »»
Esnips.com/user/ma7moud
18 Thirty Papers’ ECG – Ma7moud Sho3eb
VENTRICULAR HYPERTROPHY
Note: the pattern & amplitude of QRS complexes in chest leads (V1‐6)
«« The ECG patterns recorded by the chest leads »»
BASIC KNOWLEDGE
• The normal QRS complex in chest leads: 10
1.V1 shows small R‐wave & deep S‐wave. 2.As we proceed towards V6, the height of R‐wave progressively increases & the depth of S‐wave progressively decreases.
3.Somewhere in V3 & V4, the R & S waves are equal 11 .
Esnips.com/user/ma7moud
19 Thirty Papers’ ECG – Ma7moud Sho3eb
Lt ventricular hypertrophy Rt ventricular hypertrophy
o The pattern of QRS complexes in chest leads remains the same but the amplitude of the waves increases.
o The criteria for diagnosis are: 1.SV1 > 25, or 2.RV6 > 25, or 3.SV1 + RV6 > 35.
o It is usually associated with: 1.Lt axis deviation. 2.P mitrale.
o The pattern changes: 12
1.Lead V1 & V2 show prominent R‐wave. 2.Leads V3 & V4 show equal R & S waves. 3.Leads V5 & V6 show deep S‐wave.
o The criteria for diagnosis are: 1.RV1 > 7, or 2.SV6 > 7, or 3.RV1 + SV6 > 10.
o It may or may not be associated with: 1.Rt axis deviation. 2.P pulmonale.
STRAIN PATTERN IN VENTRICULAR HYPERTROPHY
Lt ventricular hypertrophy Rt ventricular hypertrophy
Note: leads V5 & V6 Note: leads V1 & V2
o Very tall R‐waves. o Slightly depressed S‐T segments. o Inverted T‐waves.
o R & S waves. o Slightly depressed S‐T segments. o Inverted T‐waves.
o Bi‐ventricular hypertrophy:
o Tall R‐wave in V1 of Rt ventricular hypertrophy. o Deep S‐wave in V1 & V2 with tall R‐waves in V5 & V6 of Lt ventricular hypertrophy.
o The strain pattern in V5 & V6.
Esnips.com/user/ma7moud
20 Thirty Papers’ ECG – Ma7moud Sho3eb
«« Lt ventricular hypertrophy »»
«« Rt ventricular hypertrophy »»
Esnips.com/user/ma7moud
21 Thirty Papers’ ECG – Ma7moud Sho3eb
BUNDLE BRANCH BLOCK
Note: the width of QRS complex
«« The shape of the QRS complex in V1 & V2 »»
BASIC KNOWLEDGE
• The width of QRS complex or interval is measured from the beginning of Q or R wave to the end of QRS complex.
Esnips.com/user/ma7moud
22 Thirty Papers’ ECG – Ma7moud Sho3eb
Lt BBB Rt BBB
oWide QRS complex ≥ 3 small squares o Very deep & broad S‐wave with no R‐wave in V1. o Broad slurred R‐wave or R R’ pattern with no Q‐ wave in V5 & V6.
o It is always associated with: § Lt axis deviation.
oWide QRS complex ≥ 3 small squares o R S R’ pattern (M pattern) in V1. o Broad slurred S‐wave in V5 & V6.
o It may be associated with: § Rt axis deviation.
Esnips.com/user/ma7moud
23 Thirty Papers’ ECG – Ma7moud Sho3eb
v Lt anterior hemi‐block LAHB = Pure Lt axis deviation:
1.Q‐R pattern in lead I. 2.R‐S pattern in lead III.
v RBBB with LAHB: (common because both bundles have common blood supply)
= RBBB with Lt axis deviation.
RBBB • R S R’ pattern in V1 & broad shallow S‐wave in V5 & V6.
LAHB • Lt axis deviation (Left Leaves).
Esnips.com/user/ma7moud
24 Thirty Papers’ ECG – Ma7moud Sho3eb
«« LBBB »»
«« RBBB »»
Esnips.com/user/ma7moud
25 Thirty Papers’ ECG – Ma7moud Sho3eb
MYOCARDIAL ISCHEMIA (ACUTE)
Note: S‐T segment
During angina (& During stress or exercise
test) After the attack infarction
• Plane or downward sloping S‐T segment depression (temporary).
• normal ECG. • S‐T segment elevation.
o The criteria for diagnosis of acute myocardial ischemia are: 1.Depression of J point > 1 mm. 2.Plane or downward sloping S‐T segment depression.
«« Types of S‐T segment depression »»
myocardial ischemia • Plane (horizontal) depression with sharp angle with the T‐wave.
early manifestation of ischemia
• Absolutely Horizontal (iso‐electrical) with sharp angle with the T‐ wave.
severe ischemia or digitalis toxicity
• Downward sloping depression.
Suggesting of ischemia • Sagging & concave upwards.
variant of normal • Upward sloping depression.
Significant ischemia • Upward sloping depression with J point depression ≥ 2 mm.
Esnips.com/user/ma7moud
26 Thirty Papers’ ECG – Ma7moud Sho3eb
MYOCARDIAL ISCHEMIA (NON ACUTE)
Note: S‐T segment
During angina (& During stress or exercise
test) After the attack
• S‐T segment depression & symmetrical T‐wave inversion.
• normal ECG. but may be:
1. Slight S‐T segment depression.
2. T‐wave inversion or flattening. (like strain pattern in LV hypertrophy).
o The criteria for diagnosis of non‐acute myocardial ischemia are: 1.S‐T segment depression in V5 & V6. 2.T‐wave inversion or flattening (especially in limb leads).
MYOCARDIAL INFARCTION
• MI produces 3 basic changes in the leads facing the infracted wall: 1.Elevation of S‐T segment
Indicating
zone of injury.
2.Inversion of T‐wave The effect of surrounding ischemic zone.
3.Deep & wide Q‐wave 13 The zone of infarct or dead muscle.
• Diagnosis is supported by reciprocal changes in the leads facing the opposite walls. • Theses leads will show: 1.Depression of S‐T segment. 2.Tall upright T‐wave.
• The first changes to appear are 14 : 1.Elevation of S‐T segment. 2.Tall upright T‐wave.
Esnips.com/user/ma7moud
27 Thirty Papers’ ECG – Ma7moud Sho3eb
Q‐wave S‐T segment T‐wave On the 4 th day
No. Elevated. Tall & upright.
Over the next 2 days Gradually become inverted.
By the end of the 1 st
week Starts appearing.
Starts returning to normal.
Deeply inverted.
In the 3 rd week Fully apparent. Gradually become flat & starts returning to normal.
By the end of the 3 rd
month Remain permenant 15 .
Return to normal.
Esnips.com/user/ma7moud
28 Thirty Papers’ ECG – Ma7moud Sho3eb
LOCALIZATION OF THE ISCEMIC AREA OR INFARCT
v ANTERIOR INFARCTION: o Leads I, aVL & chest leads (V1 ‐6).
& also show reciprocal changes (S‐T segment depression) in inferior infarction.
v INFERIOR INFARCTION: o Leads II, III & aVF.
& also show reciprocal changes (S‐T segment depression) in anterior infarction.
S‐T segment elevation Site of infarction
• V2‐4. oAntero‐septal infarction.
• V4‐6. oAntero‐lateral infarction.
• V1‐6. oExtensive anterior infarction.
«« Anteroseptal myocardial infarction »»
Esnips.com/user/ma7moud
29 Thirty Papers’ ECG – Ma7moud Sho3eb
THE REFERENCES
1. Video Atlas ECG ‐ Cassette clinics, Dr. Ghanashyam Vaidya.
2. The ECG made easy – 7 th edition, John R. Hampton.
3. ABC of clinical electrocardiography.
USEFUL WEB SITES
1. emedu.org/ecg/index.htm
2. ecglibrary.com
3. nobelprize.org/educational_games/medicine/ecg/
Esnips.com/user/ma7moud
30 Thirty Papers’ ECG – Ma7moud Sho3eb
( 1 ) The pen of the ECG machine.
( 2 ) Rhythm strip: A single lead is recorded simply to show the rhythm.
( 3 ) The letters P,Q,R,S & T were selected in the early days of ECG history, & were chosen arbitrarily (not based on objective facts, reasons, or principles).
( 4 ) If the first deflection is downward it is a Q‐wave. Any upward deflection is an R‐wave. A downward deflection after an R‐wave is an S‐wave.
( 5 ) logically, it should be called ‘P‐Q interval’ but common usage is ‘P‐R interval’.
( 6 ) The word ‘lead’ is sometimes used to mean the pieces of wire that connect the patient to the ECG recorder. Properly, a lead is an electrical picture of the heart.
( 7 ) Lead I records the potential difference between LA & RA, Lead II between LL & RA & Lead III between LL & LA.
( 8 ) The cardiac axis is sometimes measured in degrees, though this is not clinically useful: Lead I is taken as looking at the heart from 0 o , Lead II from +60 o & so on … Minor degrees of right & left axis deviations occur in tall, thin individuals & in short, fat individuals respectively.
( 9 ) The normal depolarization wave spreads through the ventricles from 11 o’clock to 5 o’clock.
( 10 ) Note that: • The septum is depolarized from the left to the right side. • The LV exerts more influence on the ECG than the RV.
( 11 ) This is called the ‘transition point’ which indicates the position of the inter‐ventricular septum. If the RV is enlarged, the transition point will move from its normal position of leads V3 & V4 to leads V4 & V5 or sometimes V5 & V6. This ‘clockwise rotation’ is characteristic of chronic lung disease.
( 12 ) To summarize: Prominent R‐wave in V1 & deep S‐wave in V6.
( 13 ) Q‐wave may be normally present due to a high diaphragm, so repeat ECG during deep inspiration.
( 14 ) An ECG taken immediately after the onset of chest pain may be normal & it must be repeated after a few hours if MI is suspected clinically.
( 15 ) Its size is proportionate to the size of infarct. Of course, if the size of the infarct is very small the Q‐wave may completely disappear.