경희대학교 의과대학·의학전문대학원

(1)

EKG

순환기 내과

김 수 중

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Cardiac Conduction

System

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Normal Waves of

EKG

(4)

ECG Waves



P wave

: the _{: the}sequential_sequential activation _activation (depolarization) of the

(depolarization) of the right and then left atriaright and then left atria 

QRS complex

_:_:

1

1stst phase – Dep. of IVS from Lt. to Rt phase – Dep. of IVS from Lt. to Rt

2

2ndnd phase- Simultaneous Dep. of RV & LV phase- Simultaneous Dep. of RV & LV



T wave

_{: ventricular repolarization}_{: ventricular repolarization}



U wave

_{: origin for this wave is not clear}_{: origin for this wave is not clear}

probably represents "afterdepolarizations" in

the

(5)



P Wave

It is important to remember that the P wave It is important to remember that the P wave represents the

represents the sequentialsequential activation of the activation of the right and left atria, and it is common to see right and left atria, and it is common to see notched or biphasic P waves of right and

notched or biphasic P waves of right and left atrial activation.

left atrial activation.

 P duration < 0.12 secP duration < 0.12 sec

P amplitude < 2.5 mm P amplitude < 2.5 mm

Frontal plane P wave axis: 0

Frontal plane P wave axis: 0oo to +75 to +75oo

May see notched P waves in frontal May see notched P waves in frontal plane

plane

ECG Waves

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ECG Waves

(7)



QRS Complex

simultaneous

activation of the right and

left ventricles, although most of the QRS

waveform is derived from the larger left

ventricular musculature.



QRS duration

<

0.10 sec

QRS amplitude variable

2 determinates of QRS voltages are:

 Size of the ventricular chambers (i.e., the Size of the ventricular chambers (i.e., the

larger the chamber, the larger the voltage)

 Proximity of chest electrodes to ventricular Proximity of chest electrodes to ventricular

ECG Waves

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ECG

Waves



Normal q-waves

 reflect normal reflect normal

septal activation

septal activation  they are narrow they are narrow

(<0.04s duration) (<0.04s duration) and small (<25% and small (<25% the amplitude of the amplitude of the R wave). the R wave).  Should not Should not

confused with

path` Q wave

(9)

ECG ECG Waves Waves 

R waves

- normal septal r - normal septal r wave wave in Rt. precordial in Rt. precordial leads leads - normal R wave - normal R wave progression progression - tall R wave in Lt. - tall R wave in Lt. precordial leads precordial leads 

S wave

decrease decrease progressively from progressively from Rt.to Lt Rt.to Lt

(10)

ECG Waves

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

T wave

 usually in the same direction as the QRS except in usually in the same direction as the QRS except in

the right precordial leads(reversed direction of

Rep.).

 In the normal ECG, the T wave is always upright in In the normal ECG, the T wave is always upright in

leads I, II, V3-6, and always inverted in lead aVR.



U wave

 Small(<1mm), round deflection following T waveSmall(<1mm), round deflection following T wave  Same polarity as T waveSame polarity as T wave

 Abnormal inc. in hypokalemia or drug(quinidine,Abnormal inc. in hypokalemia or drug(quinidine,

procainamide,disopyramide)

 Marker of inc. susceptibility to torsades de Marker of inc. susceptibility to torsades de

pointes

 Best seen in Rt. precordial lead / slow HRBest seen in Rt. precordial lead / slow HR

ECG Waves

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ECG Waves

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Interval &

Duration

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 PR interval: from onset of atrial PR interval: from onset of atrial

depolarization (P) depolarization (P)

to onset of ventricular depolarization (QRS) to onset of ventricular depolarization (QRS)

 QRS duration: duration of ventricular QRS duration: duration of ventricular

muscle

muscle depolarizationdepolarization

 QT interval: duration of ventricular QT interval: duration of ventricular

depolarization

depolarization and repolarizationand repolarization

 RR interval: duration of ventricular cardiac RR interval: duration of ventricular cardiac

cycle cycle

(an indicator of ventricular rate) (an indicator of ventricular rate)

 PP interval: duration of atrial cycle PP interval: duration of atrial cycle

(an indicator or atrial rate) (an indicator or atrial rate)

Interval &

Duration

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Interval &

Duration

 PR Interval : 0.12 - 0.20 sec PR Interval : 0.12 - 0.20 sec

 QRS Duration : 0.06 - 0.10 secQRS Duration : 0.06 - 0.10 sec

 QT Interval (QTc QT Interval (QTc < 0.40 sec) < 0.40 sec)

 Bazett's Formula: Bazett's Formula:

QTc = (QT)/SqRoot RR

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Rate

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Axis

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Axis

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Axis

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Axis

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Axis

Unipolar leads

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Major ECG

Abnormalities



Cardiac Enlargement &

Hypertrophy



Bundle Branch Block

(23)

Cardiac Enlargement &

Hypertrophy



RAE



Increase in P

wave amplitude

(>2.5mm)



LAE



Biphasic P wave

in V1 broad (-)

component



Broad(>120ms)

notched P wave

in limb leads

(24)

Cardiac Enlargement &

Hypertrophy

(25)

Hypertrophy

LA

E

(26)

Hypertrophy



RVH

 Tall R in V1(R/S>1)Tall R in V1(R/S>1)  RADRAD

 RV strain patternRV strain pattern



LVH

 SV1 +(RV5 or SV1 +(RV5 or

RV6)>35mm RV6)>35mm

 RV5 or RV6>25mmRV5 or RV6>25mm  LV strain patternLV strain pattern  RaVL>11~13, RaVL>11~13,

RaVF>20mm RaVF>20mm

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Hypertrophy

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Hypertrophy

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Bundle Branch Block



RBBB

 QRS vector toward Rt.QRS vector toward Rt.  QRS-T wave discordanceQRS-T wave discordance  Cong. Ht. dis, VHD, IHDCong. Ht. dis, VHD, IHD  LBBBLBBB

 QRS vector toward Lt.QRS vector toward Lt.  Septal Dep. from Rt. to Septal Dep. from Rt. to

Lt.

(30)

Bundle Branch Bundle Branch Block Block

RBB

B

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Bundle Branch Bundle Branch Block Block

LBB

B

(32)

Myocardial Ischemia &

Infarction



Factors

 Nature of process : reversible vs Nature of process : reversible vs

irreversible

 Extent : trnasmural vs subendocardialExtent : trnasmural vs subendocardial  Duration : acute vs chronicDuration : acute vs chronic

 LocalizationLocalization

(33)

Myocardial Ischemia &

Infarction

 IschemiaIschemia

 Resting membrane Resting membrane

potential decreaed potential decreaed

 Shortening of action Shortening of action

potential potential

 voltage gradient betw. voltage gradient betw.

normal normal

& ischemic zone & ischemic zone

 Current Current

 ST segment deviationST segment deviation

 T wave inversion T wave inversion

 Repolarizaion prolongedRepolarizaion prolonged  a/w QT lengtheninga/w QT lengthening

(34)

Infarction

ST

(35)

Infarction

Exercise

ECG

(36)

Infarction

(37)

Infarction

(38)

Infarction

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Infarction

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Infarction

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Infarction

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Infarction

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Infarction