Adel Hasanin, MRCP (UK), MS (Cardiology) Adel Hasanin, MRCP (UK), MS (Cardiology) Adel Hasanin, MRCP Adel Hasanin, MRCP (UK) (UK)
Jan 20, 2016
Adel Hasanin, MRCP (UK), MS (Cardiology)Adel Hasanin, MRCP (UK), MS (Cardiology)
Adel Hasanin, MRCP Adel Hasanin, MRCP (UK)(UK)
Generation and Conduction of Generation and Conduction of Electrical Current in the HeartElectrical Current in the Heart
Junction
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Electrocardiograph PaperElectrocardiograph Paper
► The The time time is measuredis measured horizontally horizontally and the and the voltage voltage is measuredis measured vertically vertically. .
► Each 1 second is represented by 5 large boxes (each Each 1 second is represented by 5 large boxes (each large box large box represents represents 0.2 0.2 second)second)
► Each large box is divided horizontally into 5 small boxes (each Each large box is divided horizontally into 5 small boxes (each small boxsmall box represents represents 0.04 0.04 secondsecond) )
► Each 1 mV is represented by 2 large boxes (each Each 1 mV is represented by 2 large boxes (each large boxlarge box represents represents 0.5 mV0.5 mV) )
► Each large box is divided vertically into 5 small boxes (each Each large box is divided vertically into 5 small boxes (each small boxsmall box represents represents 0.1 mV0.1 mV) )
1 mm=
0.1 mV
1mm=0.04 sec
------0.2 sec------ 1 second
0.5mV
1 mV
Adel Hasanin, MRCP (UK)
ECG Waves and IntervalsECG Waves and Intervals
• Normal P wave = impulse generated at sinus node and conducted through the atrium
• Normal PR interval = impulse conducted through the AV node to the ventricle
• Normal QRS = impulse generated above the ventricle and conducted through both bundles to the ventricles
• ST-T = ventricular repolarization
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PR IntervalPR Interval
► PR interval Represents the PR interval Represents the interval from the onset of atrial interval from the onset of atrial depolarization to the onset of depolarization to the onset of ventricular depolarization (i.e. ventricular depolarization (i.e. The atrial depolarization plus The atrial depolarization plus the physiological delay at the the physiological delay at the AV nodeAV node).).
► Measured fromMeasured from beginning beginning of the of the P wave to P wave to beginningbeginning of the of the QRS.QRS.
► Normal PR interval = Normal PR interval = 0.12 – 0.2 0.12 – 0.2 sec. sec. (3-5 small boxes)(3-5 small boxes)
PRInterval
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QRS ComplexQRS Complex
► QRS complex Represents QRS complex Represents the simultaneous the simultaneous depolarization of both right depolarization of both right and left ventricles and left ventricles
► Normal QRS durationNormal QRS duration ≤ ≤ 0.11 0.11 second second (~ 3 small boxes) (~ 3 small boxes)
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Narrow vs. Wide QRS ComplexNarrow vs. Wide QRS Complex
► Normal (narrow) QRS implies:Normal (narrow) QRS implies: beat beat arisingarising from above the ventricle from above the ventricle
(SAN, atrium, or junction) (SAN, atrium, or junction) andand conducted normallyconducted normally
► Wide QRS complex implies:Wide QRS complex implies: Beats Beats arisingarising from the ventricle (PVC, from the ventricle (PVC,
VT, electronic pacemaker)VT, electronic pacemaker)oror
Beats arising from above the ventricle Beats arising from above the ventricle but abnormally but abnormally conductedconducted due to due to
►BBB or BBB or ►Accessory pathwayAccessory pathway
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Systematic Rhythm Systematic Rhythm recognitionrecognition
Rhythm analysis impliesRhythm analysis implies: : 1.1. Identifying site ofIdentifying site of impulse formation (sinus, atrium, impulse formation (sinus, atrium,
Junction, ventricle)Junction, ventricle)2.2. Identifying the sequence ofIdentifying the sequence of impulse conduction impulse conduction
To identify the heart rhythm, answer the following To identify the heart rhythm, answer the following 5 questions5 questions: :
1.1. Are normal Are normal P wavesP waves present? present?
2.2. Is Is PR interval is normalPR interval is normal? ?
3.3. Are the Are the QRS complexesQRS complexes narrow or wide? narrow or wide?
4.4. Is the rhythm Is the rhythm regular regular or irregular?or irregular?
5.5. Is the Is the HRHR normal, fast, or slow? normal, fast, or slow?Adel Hasanin, MRCP (UK)
1) Are 1) Are P wavesP waves present? present?
P wave is not visible or retrograde, P wave is not visible or retrograde, QRS is narrow, rhythm is regular QRS is narrow, rhythm is regular and HR is and HR is slowslow → → junctional junctional rhythmrhythm
P wave is not visible or retrograde, P wave is not visible or retrograde, QRS is narrow, rhythm is regular QRS is narrow, rhythm is regular and HR is and HR is normalnormal → → accelerated accelerated junctional rhythmjunctional rhythm
P wave is not visible or retrograde, P wave is not visible or retrograde, QRS is narrow, rhythm is regular QRS is narrow, rhythm is regular and HR is and HR is 100-130100-130 → → junctional junctional tachycardiatachycardia
P wave is not visible or retrograde, P wave is not visible or retrograde, QRS is narrow, rhythm is regular QRS is narrow, rhythm is regular and HR is and HR is 150-250150-250 → → SVTSVT Adel Hasanin, MRCP (UK)
1) Are 1) Are P wavesP waves present in normal present in normal morphology?morphology?
Normal P wave before each QRS Normal P wave before each QRS and normal PR interval, QRS is and normal PR interval, QRS is narrow, rhythm is regular and HR is narrow, rhythm is regular and HR is normal → normal → NSRNSR
P waves replaced with saw teeth P waves replaced with saw teeth waves and waves and QRS is narrowQRS is narrow → → Atrial flutterAtrial flutter
P waves replaced with fibrillatory P waves replaced with fibrillatory waves, QRS is narrow and waves, QRS is narrow and rhythm is rhythm is irregularirregular→ → AFAF
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2) 2) PR intervalPR interval??
PR is variable with dropped beats , QRS is narrow and rhythm is irregular → 2nd degree mobitz I (wenckebach phenomenon)
PR is constant with dropped beats , QRS is narrow and rhythm is irregular → 2nd degree mobitz II
PR is extremely variable, QRS is wide, Rhythm is regular and HR is slow → 3rd degree AV block
PR interval is prolonged, QRS is narrow and rhythm is regular→ First degree AV block
Adel Hasanin, MRCP (UK)
3) Are the 3) Are the QRS complexesQRS complexes narrow or narrow or wide?wide?
Wide QRS regular Wide QRS regular tachycardiatachycardia and no visible normal P waves → and no visible normal P waves → ventricular tachycardiaventricular tachycardia
Wide QRS regular Wide QRS regular bradycardiabradycardia, no , no relation between the P waves and the relation between the P waves and the QRS complexes → QRS complexes → complete heart complete heart blockblock
Wide QRS regular Wide QRS regular bradycardiabradycardia and no P waves → and no P waves → idioventricular rhythmidioventricular rhythm
Wide QRS rhythm and Wide QRS rhythm and spikespike before each QRS → before each QRS → Pacer Pacer rhythmrhythm
Wide QRS complex(es) comes Wide QRS complex(es) comes earlierearlier than expected than expected (irregularity) (irregularity) → → PVCPVC
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Polymorphic VT (Torsades de pointes)
Spindles & Nodes
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3) Are the 3) Are the QRS complexesQRS complexes narrow or narrow or wide?wide? Sinus
Tachycardia
AF
SVT
VT
Pacemaker Rhythm
LBBBLBBBLBBB
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RBBB
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Ventricular Fibrillation
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4) Is the rhythm regular or 4) Is the rhythm regular or irregular?irregular?
Regular rhythm
Regular irregularity
Irregular irregularity
Additional rhythm event
AV Block Mobitz 12ͦ2222222222222
AF
PAC PAC
CHB
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300/4=75300/4=75
7x10=707x10=70
1. Divide the constant 300 by the number of large boxes in single cycle (single RR 1. Divide the constant 300 by the number of large boxes in single cycle (single RR interval) or divide the constant 1500 by the number of small boxes in single cycleinterval) or divide the constant 1500 by the number of small boxes in single cycle
2. Count cycles (number of RR intervals) in 6 seconds (30 big boxes) and multiply by 102. Count cycles (number of RR intervals) in 6 seconds (30 big boxes) and multiply by 10
5) Is the 5) Is the HRHR normal, fast, or slow?... normal, fast, or slow?...Heart rate can be Heart rate can be calculated in 2 wayscalculated in 2 ways
1500/20=751500/20=75
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5) Is the 5) Is the HRHR normal, fast, or slow? normal, fast, or slow?
P wave is not visible or retrograde, P wave is not visible or retrograde, QRS is narrow, rhythm is regular QRS is narrow, rhythm is regular and HR is and HR is slowslow → → junctional junctional rhythmrhythm
P wave is not visible or retrograde, P wave is not visible or retrograde, QRS is narrow, rhythm is regular QRS is narrow, rhythm is regular and HR is and HR is normalnormal → → accelerated accelerated junctional rhythmjunctional rhythm
P wave is not visible or retrograde, P wave is not visible or retrograde, QRS is narrow, rhythm is regular QRS is narrow, rhythm is regular and HR is and HR is 100-130100-130 → → junctional junctional tachycardiatachycardia
P wave is not visible or retrograde, P wave is not visible or retrograde, QRS is narrow, rhythm is regular QRS is narrow, rhythm is regular and HR is and HR is 150-250150-250 → → SVTSVT Adel Hasanin, MRCP (UK)
5) Is the 5) Is the HRHR normal, fast, or normal, fast, or slow?slow?
Wide QRS regular bradycardia and no P waves → idioventricular rhythmWide QRS regular rhythm, no P waves and HR is normal → accelerated idioventricular rhythm
Wide QRS regular tachycardia and no visible normal P waves → ventricular tachycardia
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Sinus Bradycardia
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Asystole (Flat Line)
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Adel Hasanin, MRCP (UK)