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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_2818_Библиотеки_им_академика_М_И_Перельмана
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25 mm/s. 10 mm = 1 mV
17.3 Localization ofMyocardial Infarction
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I
II
III
aVR
aVL
aVF
V1
V2
V3
V4
V5
V6
Fig. 17.10 Extensive anterior wall myocardial infarction. This ECG is recorded from a 55-yearold lady suffering from severe chest pain with left ventricular failure. She was also suffering from
uncontrolled diabetes mellitus. Note the S-T segment elevation with convexity upwards in leads
V2–V6. Note that there is a rising trend of S-T segment in leads I and aVL
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I
II
III
aVR
aVL
aVF
V1
V2
V3
V4
V5
V6
Fig. 17.11 Anterior wall myocardial infarction. This ECG is recorded from a 67-year-old gentleman suffering from severe chest pain with vomiting, sweating and left ventricular failure. He was
suffering from diabetes mellitus and hypercholesterolaemia. Note the S-T segment elevation with
convexity upwards in leads V2–V6. Note that there is a rising trend of S-T segment in lead V1 also
I
aVR
V1
V4
II
III
25 mm/s. 10 mm = 1 mV
Fig. 17.12 Recent anterior wall myocardial infarction. This ECG is recorded from a 56-year-old
gentleman suffering from severe chest pain with vomiting and sweating. Note the slightly upward
curving S-T segment with deep T wave inversion in leads V2–V6
aVL
aVF
V2
V3
V5
V6
III
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17.3.1.2 Inferior Wall Myocardial Infarction
An inferior wall myocardial infarction is usually caused by occlusion of right coronary artery. The characteristic ECG changes are located in leads II, III and aVF
(Figs.17.13 and 17.14). S-T segment elevation and T wave inversion in leads II, III
and aVF may produce reciprocal changes in the form of S-T segment depression
and tall T waves in leads I, aVL and V1 to V6.
Patients with inferior wall infarction often develop sinus bradycardia, sinus
arrest and heart block. Inferior wall infarction is often associated with a right ventricular, lateral wall or posterior wall infarction. Hence, in patients suffering from
inferior wall infarction, thoroughly one must try to look for infarctions at these sites
as well.
I
II
Fig. 17.13 Hyperacute inferior wall myocardial infarction. This ECG is recorded from a 73-yearold gentleman suffering from severe chest pain with vomiting and sweating. He was also suffering
from diabetes mellitus. Note the slope elevation of S-T segment in leads II, III and aVF.This is a
very early stage of infarction
aVR
aVL
aVF
V1
V2
V3 V6
V4
V5
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I
II
III aVF
Fig. 17.14 Acute inferior wall myocardial infarction. This ECG is recorded from a 74-year-old
gentleman suffering from severe chest pain with vomiting, sweating and palpitation. He was also
suffering from diabetes mellitus and hypertriglyceridaemia. Note the S-T segment elevation with
convexity upwards in leads II, III and aVF
aVR
aVL
V1
V2
V3
V4
V5
V6
17.3.1.3 Posterior Wall Myocardial Infarction
Posterior wall myocardial infarction is usually associated with inferior wall infarction. It rarely occurs alone. Occlusion of right coronary artery or left circumex
artery leads to posterior wall myocardial infarction. None of the leads of the conventional 12 lead ECG is directly oriented towards the posterior wall of the heart.
Hence, the leads opposite to the posterior wall, i.e. anterior wall will record the
inverse or the mirror image changes. Thus the changes are recorded in leads V1–V3,
especially lead V2 (Fig.17.15). The changes in lead V2 are:
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I
II
III
Fig. 17.15 Posterior and inferior wall infarction. This ECG is recorded from a 72-year-old gentleman suffering from chest pain with vomiting and sweating. Note the tall R and T waves in leads
V1 and V2 indicative of posterior wall infarction. There are Q waves with T wave inversion in leads
II, III and aVF indicative of inferior wall infarction
aVR
aVL
aVF
V1
V2
V4
V5
V
3
V
6
1. Tall and slightly wide R wave, which is mirror image of QS complex.
2. Depressed and concave upward S-T segment (mirror image of convex upwards
S-T segment elevation).
3. Upright, tall and wide T wave (mirror image of inverted T wave).
The height of the R wave in lead V1 and/or V2 more than the depth of the S wave in
these leads is a strong indicator of posterior wall myocardial infarction. While there
are S-T segment depression in the leads V1 and V2, a true posterior lead will record
S-T segment elevation. Posterior wall infarctions are often associated with AV conduction defects and changes in sinus rate and rhythm.
230
V1 V2 V4
V5 V6
V4R
V3R
V3
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17.3.2 Right Ventricular Infarction
Right ventricular myocardial infarction is caused by proximal occlusion of right
coronary artery. Isolated right ventricular infarction is very rare. It is usually associated with inferior wall infarction. Right ventricular infarction should be suspected
in presence of inferior wall infarction, if the following changes are recorded:
1. S-T segment elevation in lead V1 and lead V4R (Fig.17.16).
2. S-T segment depression in lead V2 is 50% or less than the magnitude of S-T
segment elevation in lead aVF.
3. S-T segment elevation in leads V1–V4 but the maximum elevation will be in
lead V1 and the elevation decreases from lead V1 to lead V4. Q waves will be
absent in these leads.
4. S-T segment elevation in lead V1 and S-T segment depression in lead V2.
I II III
25 mm/s. 10 mm = 1 mV
Fig. 17.16 Inferior and right ventricular infarction. Note the tall R waves in leads II, III and aVF
with slope elevation of S-T segment indicative of hyperacute inferior wall infarction. There is S-T
segment elevation in leads V3R and V4R, which indicates right ventricular infarction
aVR aVL aVF
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Tips and Tricks
• Sometimes patient presents with severe chest pain and sweating, but ECG turns
out to be normal. In such patients, start preliminary treatment for ACS but repeat
ECG after a few minutes.
• Serial ECG is often required to make a diagnosis of myocardial infarction if the
initial ECG is normal.
• One can do an ECG with chest electrodes placed a bit up or down if the initial
ECG is normal in presence of chest pain.
• In young patients, do not ignore chest pain. ACS is not uncommon in young people.
• In young patients, always look for chest wall tenderness. It is often simple costo-
chondritis instead of ACS.
Self-Assessment Questions
1. Pathological Q wave is less than 25% of the height of the R wave. True or false?
2. Zone of myocardial injury is surrounded by the zone of myocardial necrosis in
acute myocardial infarction. True or false?
3. Tall and wide T waves are seen in hyperacute phase of myocardial infarction.
True or false?
4. Myocardial necrosis is represented in ECG by prolonged P-R interval. True
or false?
5. Poor progression of R wave amplitude in anterior wall is a feature of anterior
wall myocardial infarction. True or false?
6. Convex S-T segment elevation is seen in all of the following condi-
tion EXCEPT:
a. Constrictive pericarditis b. Ventricular aneurysm c. Myocardial infarc-
tion d. Coronary artery spasm
7. ACS includes all EXCEPT:
a. Unstable angina b. Non-S-T segment elevation myocardial infarction
(NSTEMI) c. S-T segment elevation myocardial infarction (STEMI) d.
Ventricular aneurysm.
8. In inferior wall STEMI, all of the following are seen in inferior
leads, EXCEPT:
a. S-T segment elevation b. Q waves c. Prominent U waves d. Inversion of
T waves.
9. A 60-year-old gentleman presented with history of chest pain with radia-
tion to left arm, sweating and vomiting for last one hour. ECG revealed S-T
segment elevation in leads V3–V6. There was deep symmetric inversion of
T waves and 5mm deep q waves in these leads. The patient has developed:
a. Inferior wall myocardial infarction b. Anterior wall myocardial infarc-
tion c. Posterior wall myocardial infarction d. Right ventricular myocardial infarction
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10. A 73-year-old patient is having an ECG to evaluate myocardial infarction.
Which part of the ECG complex would you focus on to identify myocardial
infarction?
a. P-R interval b. P wave c. QRS complex and S-T segment d. T wave
11. The ECG changes of myocardial infarction due to complete occlusion of
left anterior descending artery are seen in leads:
a. Leads II, III and aVF b. Leads aVL and lead I c. Leads V1–V4 d. Leads
V1 and lead V4R
12. S-T segment elevation with concavity upwards is seen in:
a. Ventricular aneurysm b. Pericarditis c. Inferior wall MI d. Anterior
wall MI.
Case Studies
1. Examine the 12-lead ECG given in Fig. 17.17 and answer the following
questions:
a. Is there any S-T segment elevation in leads II, III and aVF?
b. Is there any abnormal Q wave in leads II, III and aVF?
c. Is there any reciprocal S-T segment change in any of the 12 leads?
d. What is your diagnosis?
e. Name two conditions in which S-T segment is elevated.
I
II
III
Fig. 17.17 Identify the ECG abnormality and interpret it
aVR
aVL
aVF
V1 V4
V2
V3 V6
V5
25 mm/s. 10 mm = 1 mV
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2. Examine the 12-lead ECG given in Fig.17.18 and answer the following questions:
a. Name the leads showing S-T segment elevation.
b. Is the R wave progression normal in chest leads?
c. What is your diagnosis?
3. A 72-year-old gentleman, chronic smoker, suffering from diabetes for 23years
presented with severe chest pain, sweating and vomiting. He has past history of
hypertension and dyslipidaemia. He was in severe chest pain. The pain was radiating to left shoulder. Patient was sweating and had two episodes of vomiting.
Blood pressure was 110/76mmHg and pulse rate was 126/min. Cardiac examination revealed elevated JVP and an S4 gallop. Lungs are clear. The ECG
(Fig.17.19) was done one hour after onset of chest pain. Examine the ECG and
answer the following questions.
a. What is your diagnosis?
b. What is the main point in favour of your diagnosis?
III
V2V1
Fig. 17.18 Identify the ECG abnormality and interpret it
III III aVR aVL aVF
Fig. 17.19 Identify the ECG abnormality and interpret it
III aVR
V4V3
V4
aVL
V5
V5
aVF
V6
V6V3V2V1
234
V1 V2 V4
V5 V6
V3
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I II III
25 mm/s. 10 mm = 1 mV
Fig. 17.20 Identify the ECG abnormality and interpret it
I
II
aVR
aVL
V1 V4
V2
aVR aVLaVF
V5
V4R
V5R
III
Fig. 17.21 Identify the ECG abnormality and interpret it
aVF
c. Which important investigation will help you to conrm your diagnosis?
d. How will you differentiate this S-T segment elevation from that of acute
pericarditis?
4. Examine the 12-lead ECG (Fig. 17.20) and make your diagnosis. What is the
main point in favour of your diagnosis?
5. A 68-year-old gentleman came with history of retrosternal chest pain for last one
hour radiating to lower jaw. He had two episodes of vomiting. On examination,
his pulse rate was 106/min and blood pressure was 84/60mmHg. Heart sounds
were normal and chest was clear. Examine the ECG (Fig.17.21) and make your
V3 V6
V6R
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