5326857782404832006465_EKG normal 2023.ppt

EKG

3. INTRODUCTIONINTRODUCTION

4. • Enlargement of cardiac chambers
• Hypertrophy of cardiac muscle
• Cardiac arrhythmias
• Insufficient coronary blood flow
• Death of heart muscle and its location
• Electrolyte abnormality
What medical problems can be diagnosed with What medical problems can be diagnosed with
an ECG? an ECG?

5. An ECG is the recording (“gram”) of the electrical
activity (“electro”) of the cells of the heart (“cardio”)
that reaches the body surface
Initiates the heart muscle to contract, to pump
blood to the tissues
What is an Electrocardiogram?What is an Electrocardiogram?

6. An ECG records:
voltage on its vertical axis
time on its horizontal axis
What does an ECG actually measure?What does an ECG actually measure?

7. ELECTRICAL ACTIVITY OF ELECTRICAL ACTIVITY OF
THE HEARTTHE HEART

8. ION CONCENTRATION GRADIENT IN CELLION CONCENTRATION GRADIENT IN CELL

9. ELECTRICAL IMPULSE PROPAGATIONELECTRICAL IMPULSE PROPAGATION

10. ACTION POTENTIAL IN PACEMAKER CELLSACTION POTENTIAL IN PACEMAKER CELLS

11. ACTION POTENTIAL IN CARDIAC MUSCLE CELLSACTION POTENTIAL IN CARDIAC MUSCLE CELLS

12. ACTION POTENTIAL IN PACEMAKER CELLS
PHASE
O
Depolarization, Ca
2+
channel opened,
influx of Ca
2+
PHASE 3Repolarization, K
+
efflux from cell
PHASE 4
Resting potential, upward slope
because of “leakage” of Na
+
ACTION POTENTIAL IN CARDIAL MUSCLE CELLS
FASE O
Depolarization, Na
+
channel opened, influx
of Na
+
→ spike
FASE 1
Rapid repolarization, Na
+
channel closed,
K
+
efflux
FASE 2
Slow repolarization, balance of K
+
efflux
and Ca
2+
influx → plateau
FASE 3
Final phase of repolarization, further
efflux of K
+
. Ca
2+
removed by Na
+
-Ca
2+

exchanger, Na removed with Na
+
K
+
-ATPase
FASE 4Resting potential
ACTION POTENTIALACTION POTENTIAL

13. ELECTRICAL ACTIVITY OF THE HEARTELECTRICAL ACTIVITY OF THE HEART

14. ELECTRICAL EVENTS OF CARDIAC CYCLEELECTRICAL EVENTS OF CARDIAC CYCLE

15. RECORDING THE ECGRECORDING THE ECG

16. ECG LeadsECG Leads
1.Bipolar limb leads: Record the potential differences
between two limbs
2.Augmented unipolar limb leads: Designed to increase
the amplitude of the output of limb leads
3.Unipolar precordial leads: Record the absolute
electrical potential at each of designated torso sites

17. Limb Leads:
•RA, LA, LL, (RL for
neutral/ground)
•Record Leads I, II, III,
aVF, aVL, aVR
Precordial Leads: V1-V6

19. READING THE ECGREADING THE ECG

20. ECG ECG CalibrationCalibration
Normal size Half sizeDouble size
Amplitude
•Standard
calibration:
10mm/mV
Paper speed
•Standard calibration:
25 mm/sec

21. Amplitude
Paper Speed
Amplitude

22. 1.Rate and regularity
2.P-wave morphology
3.PR interval
4.QRS-complex morphology
5.ST-segment morphology
6.T-wave morphology
7.U-wave morphology
8.QTc interval
9.Rythm
Systematic evaluation of the ECGSystematic evaluation of the ECG

23. P waves and QRS complexes are used to determine cardiac rate and regularity
Heart rate:
1500 divided by number of small squares
300 divided by number of large squares
Normal heart rate: 60-100 beats per minute (bpm)
Rate and regularityRate and regularity

25. 1.The contour: is normally smooth and
monophasic (entirely positive or negative)
in all leads except V1 or occasionally V2
2.Upright or positive P waves are normally
seen in leads I, aVL, aVF, V4-V6 and
downward in lead aVR. P wave in lead III
may be either upright or downward.
3.P-wave duration normally ≤ 0.12 seconds
4.The amplitude normally ≤ 0.25 mV
P wave morphologyP wave morphology

27. 1.The PR interval measured from the
beginning of P wave to the
beginning of QRS complex
2.PR interval measures the time
required for an electrical impulse to
travel from the atria and pass to AV
junction
3.The duration is normally from 0.12
to 0.20 seconds
PR intervalPR interval

29. •Not every QRS complex contains a Q
wave, an R wave, and an S wave
•Q wave: initial negative deflection of QRS
complex
•R wave: first positive deflection of QRS
complex
•S wave: negative deflection following R
wave
QRS complexQRS complex

30. 1.Q wave
Q wave considered abnormal if:
•Any Q wave in lead V2-V3 ≥0.02
sec or QS complex in V2 and V3
•Q wave ≥0.03 sec and 0.1 mV
deep or QS complex in lead I, II,
aVL, aVF or V4-V6 in any two leads
of a contigous lead grouping (I,
aVL; V1-V6; II, III, aVF)

31. 2.R waves
The positive R wave normally increases in amplitude and duration from lead V1
to V4 or V5. Loss of normal R-wave progression is considered abnormal
3.S wave
S wave should be large in V1 and then progressively smaller to V6
4. Ratio of R/S amplitude in V1 and V2 is normally less than 1

32. 5.Duration of the QRS complex (QRS interval)
It normally ranges from 0.07 second to 0.11 second (less than 0.12 second).
The QRS interval has no lower limit that indicates abnormality
6. Amplitude of QRS complex
There is no arbitrary upper limit for normal voltage of the QRS complex. An
abnormally low QRS complex when the amplitude is no more than 0.5 mV in
any limb leads and no more than 1.0 mV in any of the precordial leads

33. 7.The axis of QRS complex
•Normal axis: between –30° and +90°
•Right axis deviation (RAD): between +90° and ± 180°
•Left axis deviation (LAD): between –30° and –90°
•Extreme axis (superior axis/no man’s land): between -90° and ± 180°

34. How to determined
QRS axis?

36. 1.The ST segment measured from the end of QRS complex to the beginning of
T wave
2.The ST segment represents the beginning of ventricular repolarization
3.ST segment normally located at the same horizontal level with the PR
segment (isoelectric)
4.Normal variations:
•Slight upsloping, downsloping, or horizontal depresion
5.ST segment may be altered when there is prolonged QRS complex
ST segmentST segment

38. •The T wave represents part of ventricular repolarization
•Normally, the T waves are positively directed in all leads except aVR
(negative) and V1 (biphasic)
•T waves do not normally exceed 0.5 mV in any limb lead or 1.5 mV in any
precordial lead
T waveT wave

39. •U wave is either absent or present as a small wave following the T wave and
is usually most prominent in leads V1 and V2.
•Increased prominence of the U wave indicates the possibility of hypokalemia
U waveU wave

41. 1.The QT interval measures the duration of electrical activation and recovery of
the ventricular myocardium
2.The QT interval decreases as the heart rate increases and therefore should be
corrected for cardiac rate (QTc interval)
3.QTc= QT/RR interval (in seconds)
The upper limit of QTc is 0.46 second (slightly longer in in females)
4.QT interval varies among different leads. The longest QT interval measured in
multiple leads should therefore be considered the true QT interval
QTc intervalQTc interval

42. RhythmRhythm

44. 10 mm/mV 25 mm/s
Mr. D, 50 y.o 1/12/2021 09.30

45. Mr. A, 45 y.o 1/12/2021 09.30
10 mm/mV 25 mm/s
a
a
a

46. Mr. E, 45 y.o1/12/2021 09.40
10 mm/mV 25 mm/s

48. •Limb Leads:
–I, aVL
–II, III, aVF
•Precordial Leads:
–V1-V6
CONTIGUOUS LEADSCONTIGUOUS LEADS

50. •V7: Left posterior axillary
line
•V8: Left midscapular
•V9: Left paraspinal
Placement of posterior leads (V7-V9)Placement of posterior leads (V7-V9)

51. •Mirror image of
pericordial leads
•V3R: Between V1 (V2R)
and V4R
•V4R: Right midclavicular
line
•V5R: Right anterior
axillary line
•V6R: Right midaxillary line
Placement of Right ventricular leadsPlacement of Right ventricular leads