1. Introduction to ECG Recognition of Myocardial Infarction

2. Possibilities of an ECG of diagnostics
The ECG allows:
to diagnose a myocardium ischemia
to diagnose necrosis a myocardium
To define localisation of necrosis
Extensiveness of defeat and depth necrosis
Process stage
Some complications

3. Changes in a myocardium at CHD
At CHD in a cardiac muscle processes of an ischemia, injury and necrosis develop depending on expressiveness and character of damage of coronary arteries.
Each process in a myocardium has the ECG signs.

4. ECG at stenocardia ECG a stenocardia at a painful attack
Horizontal or down sloping slantwise downwards the directed depression of segment S-Т (below an isoline) on 1 mm
Or segment lifting S - Т above an isoline> 1мм a painful ischemia of a myocardium.

7. Ischemia Ischemia transitory disturbance of coronary arteries.
At the ECG reflect changes wave Т и segment ST, transitory.

8. Ischemia
Ischemia in subepicardial at the ECG appear transitory negative symmetrical Т wave.

9. Ischemia
Subendocardial ischemia at the ECG appear transitory high positive symmetrical wave Т.

10. Ischemia

11. Injury
At a long ischemia of a myocardium > 30 minutes, the ischemia leads more to radical changes in a myocardium, accompanied by infringements of biochemical processes in a cardiac muscle that leads to infringements of processes repolarization longer period.
On an ECG this process finds reflexion in change of segment ST and T wave.
At restoration of a coronary circulation ischemic changes remain some days (<10 days), that clinically reflects a condition of an unstable stenocardia (the Acute coronary syndrome)

12. Injury
At the subepicardial injury (or transmural injury) on the ECG appear elevation ST segment duration more exceed time heart attack.

13. Injury
At the Subendocardial injure on the ECG appear depression ST segment duration more exceed time heart attack.

14. Injury

15. At restoration of coronary blood circulation ischemia and injure processes do not lead to morphological changes in a myocardium.
At a remaining ischemia and the injure caused by the termination of a coronary circulation morphological changes in a myocardium in necrosis of cardiac muscle-development of AMI.

16. Necrosis
Necrosis a cardiac muscle it is reflected in an ECG by infringement of processes depolarization, that is reflected by changes in complex QRS

17. Necrosis

18. Necrosis At the ECG disturbance depolarization:
Pathological Q-wave (QS, or QR);
Elevation RS–T segment and
Inverted Т waves.

19. In the lead which are in a zone opposite from centre necrosis, are registered mirror changes - to Q wave there corresponds R, and to r (R) wave - a s (S) wave.
If over a zone of MI segment ST is raised by an arch upwards on opposite sites it is lowered by an arch downwards

20. At the healthy person in the lead reflecting potential LV (V5-6, I, aVL), the physiological q wave, a reflecting vector of excitation of a IVS of heart can be registered.
The physiological q wave in any leads, except aVR, should not be more than 1/4 teeth R with which it is written down (25% of R-wave amplitude), and is more long 0.03 sec.

21. Stages of development of MI
At sharp infringement of a coronary circulation in a heart muscle 3 processes consistently develop:
ischemia
injure
necrosis (infarct).
Duration preliminary to a heart attack of phases depends on many reasons: degrees and speeds of infringement of a circulation, development collaterals, etc., but usually they last from several tens minutes, till several o'clock.

22. Evolution of Acute MI
The ECG changes depending on time which has passed from the beginning of formation by MI.
Usual ECG evolution of a Q-wave MI;
Not all of the following patterns may be seen;
The time from onset of MI to the final pattern is quite variable and related to the size of MI, the rapidity of reperfusion (if any), and the location of the MI.

23. A. Normal ECG prior to MI
B. Hyperacute T wave changes - increased T wave amplitude and width; may also see ST elevation
C. Marked ST elevation with hyperacute T wave changes (transmural injury)
D. Pathologic Q waves, less ST elevation, terminal T wave inversion (necrosis)
(Pathologic Q waves are usually defined as duration >0.03 s and >25% of R-wave amplitude or > ¼ from R)
E. Pathologic Q waves, T wave inversion (necrosis and fibrosis)
F. Pathologic Q waves, upright T waves (fibrosis)

24. Evolution of Acute MI in acute (а–д), subacute (е-ж) and scarring (з) stages

25. Peracute stage
Peracute stage (tо 2-х h from start MI). Within several minutes after the termination of a coronary circulation and occurrence heart attack in a cardiac muscle the zone usually comes to light
Subendocardial eschemia, (appear high Т wave and depression RS–Т segment.
In practice these changes are registered seldom enough, and the doctor deals with later ECG signs of the sharpest stage MI.

26. Peracute stage
When the zone of ischemic injure extends to epicardium, on an ECG displacement of segment RS-Т above an isoline is fixed (transmural ischemic injure).
Segment RS-Т thus merges with positive Т wave, forming the so-called monophase curve

27. Peracute stage a) subendocardial ischemia
б) subendocardial ischemia and subendocardial injure
в) transmural injury

29. Acute stage
Is characterised fast, during day, formation of pathological Q or complex QS and decrease in amplitude of R wave that specifies in formation and zone expansion necrosis.
Simultaneously within several days over a zone necrosis displacement of segment RS-T above an isoline and merging with it positive remains in the beginning, and then negative Т wave, and in an opposite wall to a zone necrosis the ischemia of a myocardium in the form of depression of segment ST remains an ischemia of a myocardium in the form of depression of segment ST.

30. Acute stage
In some days segment RS-T comes nearer to an isoline, and by the end of 1st week or in the beginning of 2nd week of disease becomes isoline, that testifies to reduction of a zone of ischemic injure.
Negative coronary Т wave it goes deep and becomes sharp symmetric and pointed (repeated inversion of a T wave).

31. Acute stage

33. Direct signs of a sharp stage MI with Q wave
Pathological Q wave (Qr or QS);
Elevation RS–T segment and
Inverted Т waves.

34. Subacute stage
In subacute stages MI registers pathological Q wave or complex QS (necrosis) and the negative coronary Т wave (ischemia), which amplitude, since days MI, gradually decreases.
Segment RS-T is located on an isoline.
Signs a myocardium ischemia in the given stage disappear.

35. Subacute stage

36. Fibrosis stage
The cicatricial stage is characterised by IT preservation for many years pathological Q wave and complex QS (QR or Qr) and presence of negative, smoothed or positive Т wave.

37. Fibrosis stage

39. Depth of necrosis At transmural necrosis on ECG present QS complex;
At nontransmural necrosis present Qr or QR complex. 

40. Q wave MI: a) transmural necrosis, б) nontransmural

41. Localization MI Localization MI Leads Occlusion of artery An anterior
V1 - V4
Anterior Descending branch of the left CA
Inferior (diaphragmatic)
II, III, aVF
Branches of either the rigth or left CA
Lateral
I, aVL, V5, V6
Circumflex branch of the left CA
Posterior
Lardge R in V1-2,
May be Q in V6
Mirror test
Right CA or one of its branches

42. ECG with regions of the heart highlighted

43. What part of the heart is affected ?
II, III, aVF =
Inferior Wall I II
III
aVR
aVL
aVF V1 V2 V3 V4 V5 V6

44. Inferior Wall MI

45. Based on the ECG, which vessel in the heart is blocked?
II, III & aVF = Inferior Wall MI =
Right Coronary Artery
blockage

46. Which part of the heart is affected ?
Leads V1, V2, V3, and V4 =
Anterior Wall MI I II
III
aVR
aVL
aVF V1 V2 V3 V4 V5 V6

47. Anterior Wall MI

48. Based on the ECG, which vessel in the heart is blocked?
V1 - V4 = Anterior Wall
(Left Ventricle) =
Left Anterior
Descending Artery
Blockage

49. What part of the heart is affected ?
I, aVL, V5 and V6
Lateral wall of left ventricle I II
III
aVR
aVL
aVF V1 V2 V3 V4 V5 V6

50. Lateral Wall MI

51. Based on the ECG, which vessel in the heart is blocked?
I, aVL, V5 + V6 =
Lateral Wall =
Circumflex Artery
Blockage

52. ECG at the anterior MI

53. ECG at the anterior MI and apex

54. Diagram of a MI (2) of the tip of the anterior wall of the heart after occlusion (1) of a branch of the LCA

55. ECG at the lateral MI

56. ECG at MI of all anterior wall – I, avL, V1-V6

57. ECG at the inferior MI
In I, aVL, V1 –V4 leads mirror change

58. Non-Q Wave MI
Recognized by evolving ST-T changes over time without the formation of pathologic Q waves (in a patient with typical chest pain symptoms and/or elevation in myocardial-specific enzymes)
Although it is tempting to localize the non-Q MI by the particular leads showing ST-T changes, this is probably only valid for the ST segment elevation pattern

59. Non-Q Wave MI
Evolving ST-T changes may include any of the following patterns:
Convex downward ST segment depression only (common) > 48 h
Convex upwards or straight ST segment elevation only (uncommon)
Symmetrical T wave inversion only (common) > 10 days
Combinations of above changes

60. Non Q wave MI: в) depression ST segment, г) negative symmetrical Т wave

61. Non-Q Wave MI

62. Non-Q Wave MI

63. Non-Q Wave MI

64. Ischemia, Injury, and Infarct !!
Summary
After completing an ECG, look at each of the leads for ST segment changes
Remember the three I’s:
Ischemia, Injury, and Infarct !!
Identify the section of the heart (and vessel supplying it) affected by the blockage according to the groups of leads changing in the ECG
Remember the symptoms that would prompt you to obtain an ECG!