ECG Localization of culprit vessel i myocardial infraction

1. ECG LOCALIZTION OF
CULPRIT VESSEL IN MI
Dr. Ruhail Bhat

2. Coronary circulation
• LMCA give rise to LAD and LCX artery and occasionally gives Ramus
intermedius(10-15%)
• LAD – Septals
---Diagonal
---PDA& PLB in left dominant system
supplies blood to upper 2/3rd of septum, anterior, lateral wall and apex of
LV.
LCX – Obtuse marginal branches
supplies lateral wall of LV and varying amount to posterior and inferior wall.
• If ramus intermedius - supplies lateral wall of LV.

3. • RCA – conal artery(50%)
-- SA nodal artery(65%)
--AV nodal artery(90%)
-- Marginal branches
-- PLB & PDA (right dominant)
• supplies blood to right ventricle and varying amount to inferior/
posterior walls and lower 3rd of septum (depends on dominance).

5. Territorial distribution of coronaries

6. Grades of ischemia
• In leads with usual Rs
configuration:
• grade I: tall symmetrical T wave
without ST elevation;
• grade II: ST elevation without
distortion of the terminal portion
of the QRS complex;
• grade III: ST elevation with
distortion of the terminal portion
of the QRS (no S waves)

7. Leads with usual qR
configuration:
grade I: tall symmetrical T wave
without ST elevation;
grade II: ST elevation with J point/R
wave ratio <0.5
grade III: ST elevation with J point/R
wave ratio >0.5

8. Evolution Of MI

9. AWMI
• The frequency of STE in patients with acute myocardial infarction due to
LAD occlusion in descending order: V2, V3, V4, V5, aVL, V1, and V6.
• LAD occlusion  by mainly STE V2-V4.
• STE in V4-V6 without STE in V1-V3  LCX or distal diagonal branch
involvement.
• Rarely, ST in V1–V4 signifies proximal right coronary artery occlusion
with concomitant right ventricular infarction!!!!
• Differentiation from AWMI due to LAD  (points in favor of RCA)
1)ST in V1>V2
2)ST in V3R and V4R
3)ST elevation in the inferior leads II, III, and aVF

10. 4 Patterns of LAD involvement:
1. Proximal to 1st septal and 1st diagonal branches(40%)
2. Proximal to 1st septal but distal to 1st diagonal(5-10%)
3. Proximal to 1st diagonal but distal to 1st septal(5-10%)
4. Distal to 1st septal and 1st diagonal branches(40%)

12. EXTENSIVE ANTERIOR WALL MI
► LAD occlusion before
septal and diagonal i.e.
proximal LAD occlusion
 ST elevation in I, aVL and
V1-V6 WITH ST depression
in II, III, aVF
 qRBBB and ST elevaton in
aVR may also be associated

13. ANTERO SEPTAL MI
► LAD occlusion proximal
to septal branch distal
toD1.
► ST elevation in V1
>2.5mm
OR
► ST elevation in aVR
OR
► qRBBB alongwith ST
elevation in V2- V4
AND
❖ ST depression in II, III,
aVF

14. ANTERO LATERAL MI
► LAD before diagonal and
after septal branch.
 ST elevation in I, aVL in
addition to V2 to V4
 ST may be depressed in V5
and V6

15. ANTERO-APICAL MI
► Occlusion of LAD after septal
and diagonal branch
 ST elevation in V5 and V6 in
addition to V2-V4 with
 ST depression in aVL
► ST elevation in II, II aVF in
addition signifies wrap
around LAD.

17. ST in I, aVL(Selective occlusion of D1)
• Plus ST V2 and ST
/isoelectric in V3-V6 and
II,III,aVF  D1 occlusion
(south African flag pattern)
caused by acute occlusion of the first diagonal branch of the left
anterior descending coronary artery (LAD-D1)

18. Selective occlusion OF S1 branch
STE in
V1,V2,
and aVR
STD In
II,III,aVF
NO STE
in aVL

19. V2-V4

23. INFERIOR WALL MI

24. ECG changes are due to vectors being more directed
towards the right and reciprocal changes with ST depression
in leads V1-V3 being less pronounced.
► ST elevation in lead III > aVF > II.
► ST depression in I and aVL.
► ST elevation in V1, V3R and V4R (proximal RCA
occlusion)
► Sum of ST depression in V1-V3/Sum of ST elevation in
II,III,aVF is LESS THAN 1.
► ST depression in V3/ST elevation III ratio if
► <0.5 suggests Proximal RCA occlusion
► 0.5-1.2 suggests Distal RCA Occlusion
► S/R ratio in aVL is >3
► ST elevation in lead II > aVF > III.
► ST elevation in V5 and V6.
► No ST depression or sometimes ST elevation in I and aVL.
► Sum of ST depression in V1-V3/Sum of ST elevation in II,III,aVF is
MORE THAN 1.
► ST depression in V3/ST elevation ratio is >1.2
► S/R ratio in aVL is < 3
► Abnormal R in V1 of more than 40 ms or R/S in V1 >1 or
R>0.6mV
► Abnormal R in V2 of more than 50 ms or R/S in V2 >1.5 or
R>1.5 mV
► ST depression in aVR
RCA
lCX

25. LCx
Occlusion
LCx Occlusion

26. LCx versus RCA involvement

27. INFARCTION OF RIGHT VENTRICLE
► Isolated right ventricular MI is rare.
► However in 20-45% inferior wall MI, right ventricular necrosis is seen.
► ECG changes are as described :
►Elevated ST segment in extreme right oriented leads.
►In setting of acute IWMI if there is Elevation of > 1mm in lead V1, or in any one of leads
V4R to V6R, RVMI should be strongly suspected.

28. ►V4R is the most sensitive right precordial lead
►In setting of IWMI if there is failure of reciprocal ST segment depression to develop
appreciable depth in precordial leads , RVMI should be suspected. This is because ST
segment deviation towards the right ventricular surface in RV injury would tend to
nullify any other cause of ST depression.
► Thus, ST segment depression in lead V2 which is 50% or less than
ST segment elevation in aVF indicates RV ischemic injury.
► ST segment elevation in V1 and ST depression in V2 is also
indicative of RVMI due to discordant relationship.

29. ► The ECG changes of RV infarction might mimic AWMI, with significant
differences explained as follows:
►Magnitude of ST elevation from V1-V5 decreases from Right to Left in RVMI with ST
elevation being maximum in V1. Whereas in AWMI there is a increasing ST elevation from V1
to V5, being minimal in V1.
►In AWMI abnormal Q waves evolve in these leads whereas no such development or
manifestation is seen in RVMI.

30. V4R in predicting IRA

31. PROXIMAL RCA OPROXIMAL RCA OCCLUSION
CCLUSION

32. DISTAL RCA
OCCLUSION
L RCA OCCLUSION

34. Sn and Sp of various criteria

37. POSTERIOR WALL MI
► Rarely occurs as an isolated phenomenon.
► Nearly always associated with inferior wall and/or apico-lateral wall MI.
► V7 to V9 reflect the classic presentation.
► infarction of the post wall diagnosed by the inverse/mirror image changes seen in uninjured anterior
wall MI.
► Use of posterior leads is recommended to detect ST elevation consistent with Posterior MI.
V7-V9 > 0.05 mV ; or more than 0.1 in patients more than 40 years.
► The direct changes may appear to be much smaller than the reciprocal changes in V1-V3.

38. ECG changes are as follows :
► Acute PWMI ST elevation corresponds to LCx territory and shows
isoelectric ST depression > 0.05 mV in leads V1 through V3.
► Absence of precordial st depression in inferior wall infarction strongly
suggestive of RCA involvement

39. Ischemia at distance?

40. Ischemia at distance VS Reciprocal changes
• STE in one myocardial zone often have concurrent STD in other
myocardial zones.
• These may represent pure “mirror image” reciprocal changes or may
be indicative of acute ischemia due to coronary artery disease in non-
infarct related arteries (“ischaemia at a distance”).
• Eg: STD in V4-V6 in acute IWMI, does signify concomitant coronary
artery disease of the LAD vessel with acute ischaemia in a myocardial
zone remote from the infarct zone;
• These patients more likely to require MVPCI vs CABG.

41. OM VS D1 Occlusion
• OM
Injury vector left,posterior
STE I,avl and V5-V6
STE may in II,aVF
Slight STD in V1-V3
• D1
Injury vector toward
leftward,upward and anteriorly
STE I,avl and v5-V6
STE in precordial leads
STD In II,III,aVf

42. Occlusive MI without ST
elevations

44. Wellens T waves type A and B

45. • Wellen’s syndrome:
symmetric and deeply inverted T waves or biphasic T waves in leads
V2 and V3 in a pain-free state
plus isoelectric or minimally elevated (<1 mm) ST segment
absence of precordial Q waves, the presence of history of angina, and
normal or slightly elevated cardiac serum markers
• Suggests critical proximal LAD occlusion

46. Diffuse ST depression with ST elevation in aVR– occlusive MI without ST elevation– left main
or TVD (bcz of transmural ischaemia in the basal portion of the interventricular septum
(LAD), or transmural ischaemia in the RVOT caused (RCA). (Sn 80 Sp 93)

47. Predictive Value of STE in aVR
• In the context of widespread ST depression +
symptoms of myocardial ischaemia:
 STE in aVR ≥ 1mm indicates proximal LAD / LMCA occlusion or
severe 3VD
 STE in aVR ≥ V1 differentiates LMCA from proximal LAD
occlusion
• Absence of ST elevation in aVR almost entirely
excludes a significant LMCA lesion
• In the context of anterior STEMI:
 STE in aVR ≥ 1mm is highly specific for LAD
occlusion proximal to the first septal branch

48. De winter T waves??
Criteria for de winter
sign:
Tall, prominent,
symmetrical T waves in
the precordial leads
Upsloping STD > 1mm
at the J point in the
precordial leads
Absence of STE in the
precordial leads
2% of cases with
proximal LAD occlusion

49. MI WITH LBBB
Diagnosing acute AWMI with LBBB
► New onset LBBB in conjunction with symptoms suggests
acute MI.
► In patients with documented LBBB earlier its difficult to
diagnose AWMI because of masking effect of LBBB on
QRS/ST/T changes.
► Such cases are solved by SGARBOSSA Criteria by which is
as follows :
► ST elevation in at least one lead, of >1mm,
concordant to the positive QRS complex (5 Points)
► ST depression > 1mm in V1 to V3 (3 Points)
► Discordant ST elevation of >5mm in at least one
leads with a predominant negative QRS (2 points)
► Positive T waves in V5-6 also signifies acute ischemia in
presence of LBBB.

50. Smith-Modified Sgarbossa Criteria:

51. Diagnosing
Acute IWMI
with LBBB
► There is no
masking effect
of LBBB on
inferior leads
so it can be
diagnosed
routinely.
Diagnosing Old AWMI with LBBB
► LBBB may mask the features of Old AWMI.
► Following signs in presence of LBBB are
suggestive of old AWMI :
► Presence of q waves in V5-V6, I or aVL.
► Notching of 50ms on the ascending limb of
S wave of V3-V5 (CABRERA’s SIGN).
► Notching in the upstroke of R waves in
lead I, aVL or V6 (CHAPMAN SIGN)

52. Barcelona algorithm for dx MI in LBBB
• ST deviation ≥1 mm (0.1 mV) concordant
with QRS polarity in any ECG lead, including
either:
1. STD ≥1 mm (0.1 mV) concordant with QRS
polarity, in any ECG lead.
2. STE ≥1 mm (0.1 mV) concordant with QRS
polarity, in any ECG lead (Sgarbossa score 5).
• ST deviation ≥1 mm (0.1 mV) discordant
with QRS polarity, in any lead with max
(R|S) voltage ≤6 mm (0.6 mV)
• higher sn (95%) and sp (89%) compare to
sgarbossa

53. ASLANGER PATTERN
• CRITERIA
• 1) STE in III but not in
any other inferior lead,
(2) ST depression in any
of leads V4 to 6 (but not
in V2) with a positive
(at least terminally
positive) T-wave,
(3) ST in lead V1 higher
than ST in V2.
• 13.3% IWMI wrongly
labelled as NSTEMI due
to this pattern.

55. INFARCTION OF ATRIA
► Isolated atrial infarction is rare.
► The diagnosis of atrial MI is made from elevation of PTa segment in setting of MI.
► PTa segment is that part of PR interval which extends from end of P wave to beginning of ORS
complex. It reflects atrial repolarization, ending In Ta wave.
► Pta is usually minimally displaced in direction opposite to that of P wave.
► Occurs in 10% of inferiorpost mi
► Pta elevation occurs in I,II,III,V5 or V6 or depression in precordial leads

57. Estimating size and severity of myocardial injury infarct STEMI based on ECG :
1. Number of leads with ST elevation(especially correlates with anterior
infarcts) and degree of ST elevation(especially correlates with inferior
infarcts.
1. Aldrich score for estimating myocardium at risk of infarct and represented
by the formula:
► % LV myocardium at risk of infarction in IWMI
3 [0.6*(Sum ST elevation II, III, aVF) + 2]
► % LV myocardium at risk of infarction in AWMI
3 [1.5*(Number of leads with ST elevation) – 0.4]

58. 2. Sclarovsky – Birnbaum grading
► For estimation of severity of ischemia, as follows:-
►Grade I- tall , peaked, symmetrical T waves.
►Grade II –slope elevation of the ST segment.
►Grade III-distortion of the terminal QRS complex in form of J point elevation of >50% of
the preceding R or loss of normal S wave.
3.SELVESTER score
4.Determine Score