Điện tâm đồ trong nhồi máu cơ tim

Điện tâm đồ
trong nhồi
máu cơ tim
TS. Đinh Hiếu Nhân


Acute Myocardial Infarction
• ST segment elevation MI – persistent complete occlusion of an
artery supplying a significant area of myocardium without adequate
collateral circulation
• UA/NSTEMI – result from non-occlusive thrombus, small risk area,
brief occlusion, or an occlusion with adequate collaterals


I. Chẩn đoán NMCT




ECG trong NMCT
• Chẩn đoán (+) NMCT cấp có ST chênh lên.
• Chẩn đoán giai đoạn NMCT cấp.
• Chẩn đoán vùng NMCT.
• Chẩn đoán biến chứng RLNT


ECG changes in AMI
• In the early stages of AMI the ECG may be normal
• <50% of patients with AMI have clear diagnostic
changes on their first trace.
• About 10% of patients with a proved acute myocardial

infarction fail to develop ST segment elevation or
depression.
• In most cases, however, serial ECG’s show evolving
changes that tend to follow well recognised patterns.


Biến đổi ECG trong NMCT
• ST – T chênh lên.
• Sóng Q bệnh lý


J point

ST segment

Last deflection of QRS


Sự tạo thành các biến đổi của sóng
ECG trong NMCT


Tạo thành sóng Q


Tạo thành đạon ST chênh lên hay
chênh xuống


Đoạn ST

• ST segment of the cardiac cycle represents the period between
depolarization and repolarization of the left ventricle
• In normal state, ST segment is isoelectric relative to PR segment


Minnesota Code
• The Minnesota code 9-2 requires ≥1 mm ST elevation in one or
more of leads I, II, III, aVL, aVF, V5, V6, or ≥ 2 mm ST elevation in
one or more of leads V1–V4
• Menown IB, Mackenzie G, Adgey AA. Optimizing the initial 12-lead electrocardiographic
diagnosis of acute myocardial infarction. Eur Heart J 2000; 21 (4):275-83.

• Đoạn ST chênh lên ở ít nhất 2 chuyển đạo kế tiếp nhau


ST Segment
Elevation


Acute Myocardial Infarction
• Irrespective of which definition is used, ST elevation has poor
sensitivity for AMI where up to 50% of patients exhibit ‘atypical’
changes at presentation including isolated ST depression, T
inversion or even a normal ECG
• Menown IB, Mackenzie G, Adgey AA. Optimizing the initial 12-lead electrocardiographic
diagnosis of acute myocardial infarction. Eur Heart J 2000; 21 (4):275-83.


How To Differentiate STE due
to AMI from Other Causes?

• Magnitude of the elevation
• Morphology
• Distribution
• Prominent Electrical Forces (Voltage Amplitude)
• QRS width
• Other Features


Morphology of the
ST Elevation


Variable Shapes Of ST
Segment Elevations in AMI

Goldberger AL. Goldberger: Clinical Electrocardiography: A Simplified Approach. 7th
ed: Mosby Elsevier; 2006.


Morphology of STE
• Concave shape STE – non AMI causes
• AMI causes – usually demonstrate convex/straight STE

Apex of T wave

J point

Convex STE

Concave STE

Benign Early Repolarization
Concave STE

Large amplitude T
wave

Notching or slurring of
J point


Benign Early Repolarization
•
1.
2.
3.
4.

ECG characteristics:
STE <2 mm
Concavity of initial portion of the ST segment
Notching or slurring of the terminal QRS complex
Symmetrical, concordant T wave of large
amplitude
5. Widespread or diffuse distribution of STE
o Does not demonstrate territorial distribution

6. Relative temporal stability

Distribution
• STE due to AMI usually demonstrate regional or territorial pattern
•
•
•
•
•
•

Examples:
Anterior MI – V3-V4
Septal MI – V2-V3
Anteroseptal MI – V1/2 – V4/5
Lateral MI – V5/V6
Inferior MI – II, III, aVF

• Diffuse STE – non AMI causes, e.g. pericarditis


Lateral Wall MI: I, aVL, V5, V6

Source: The 12-Lead ECG in Acute Coronary Syndromes, MosbyJems, 2006.


Inferior Wall MI II, III, aVF

Source: The 12-Lead ECG in Acute Coronary Syndromes, MosbyJems, 2006.