localization of culprit artery in stemi dr bijilesh u senior resident, dept. of cardiology, medical...
TRANSCRIPT
Localization of culprit artery in STEMI
Dr Bijilesh uSenior Resident,
Dept. of Cardiology,Medical College, Calicut
Careful analysis of the Surface ECG is highly useful in localizing the culprit vessel and immediate prognostication
Helps in deciding the need for an aggressive reperfusion strategy
Coronary circulation
Left Main or left coronary artery (LCA) – Left anterior descending (LAD)
• diagonal branches (D1, D2) • septal branches
– Circumflex (Cx) • Marginal branches (M1,M2)
Right coronary artery – Conus , sinoatrial branch– RV branch– Acute marginal branch (AM) – AV node branch – Posterior descending artery (PDA)
LAD large MIs– Supplies the anterior, lateral, anterior two-
thirds of septum, and frequently the inferoapical segments of the left ventricle, proximal part of bundle branches
RCA– Perfuses sinus node (55%), AV node,
posteromedial papillary muscle, inferior part of LV, RV, and variably also the posterior and lateral segments
Circumflex branch
– Posterior wall and variably inferior and lateral segments
– Posterior wall involvement usually underestimated and under treated.
SA node – RCA in 55% AV node – RCA in 90% Bundle of His – mainly RCA RBB – LAD LBB – L Ant branch – LAD
L Post branch – LAD & Postr Desend A
Dominance
Supplies circulation to the inferior wall & inferior portion of the interventricular septum
Passes crux and interventricular septum, giving rise to posterolateral branches & PDA
Dominant artery also gives rise to the AV nodal branch
RIGHT DOMINANT
LEFT DOMINANT
Dominance
RCA - 70% LCX - 10% Co - dominant – 20%
Identifies patients at risk for extensive myocardial damage with complications
ST VECTOR Direction and displacement of the ST
segment - sum of direction and magnitude of all ST vectors
Resulting main vector point in the direction of the most pronounced ischemia - ST elevation in that area
Opposite area record (reciprocal) ST depression
Lead perpendicular to dominant - iso-electrical ST segment
AWMI
ECG in AWMI
STE in V2, V3, V4
Behaviour of ST in other leads depends on the presence of ischemia in three vectorally opposite areas
– Basoseptal area (1st septal branch)– Basolateral area (1st diagonal branch)– Inferoapical area ( when LAD wraps around apex)
Types of LAD occlusion
Proximal to 1st septal and 1st diagonal branch (40%)
Distal to S and D (40%)
Proximal to D1 but distal to S1 (10%)
Proximal to S1 but distal to D1 (10%)
Proximal LAD occlusion (Dominance of Basal area)
Direction of ST Vector and ECG Changes inProximal LAD Occlusion
Proximal LAD occlusion (Dominance of Basal area)
ECG…
RBBB
STE aVR and STE in V1 > 2.5 mm
ST depression in inferior leads and in V5
Distal LAD occlusion(dominance of inferoapical area)
Distal LAD occlusion(dominance of inferoapical area)
ECG…
Absence of ST depression in inferior leads
STE in inferior leads in addition to V3-V6
1st Diagonal not involved(Dominance of septal area)--Proximal to S1
ECG…
STE in aVr and > 2.5 mm STE in V1
ST depression in V5
STE in V3R
ST depression in aVL (Highly specific)
1st Diagonal not involved(Dominance of septal area)
First septal branch not included(dominance of Lateral area) – Proximal to D1
ECG…
ST depression in Lead III > Lead II
ST elevation lead AVL & lead 1
First septal branch not included(dominance of Lateral area)
ECG criteria to identify site of occlusion in the LAD
Engelen et al J Am Coll Cardiol. 1999;34:389-395
Inferoposterior wall MI
Occlusion of the RCA
ST-segment elevation in III > II ST-segment depression in I and aVL - aVL > I Herz I, Assali AR et al Am J Cardiol 1997;80:1343-1345
ST depression in the precordial leads is smaller than ST elevation in inferior leads
When occlusion is proximal to RV branches ST elevation in V1 > V3 V4
LAD occlusion ST elevation in V3V4 > V1
Dominance of RCA
When RCA is dominant, ST-segment elevation is seen in V5 and V6
ST-segment elevation ≥ 2 mm - RCA very dominant
Involvement of posterior wall PR prolongation.. AV nodal artery arises
from dominant artery
Occlusion of the LCX
ST- elevation in II ≥ III ST elevation in I and aVL. ST-segment elevation in II, III, and aVF is
usually smaller than the ST depression in right precordial leads
When LCX is quite dominant - ST depression in aVL, but very rarely in I
OM vs D1 OCCLUSION
0M ST elevation I, aVL,
and V5−6 Slight ST depression in
V1-3
D1 ST elevation I, aVL,
and V5−6 ST-elevation in
precordial leads ST-depression inferior
leads.
RV infarction
STE >1mm V3R and V4R
STE V1 > V2
High degree AV block
RV infarction
Value of ST – T changes in V4R in acute infero posterior MI
(RVMI)
Braat SH, Gorgels APM, Bar FWHM, Wellens HJJ Am J Cardiol 1998;62:140-142.
Isolated RVMI
Minor changes in inferior leads,
STE prominent in leads V1 and V2 , V3R and V4R
Small or collaterally filled RCA Occlusion of an RV branch only
ST depression in anterior leads in IWMI
Implies posterior wall involvement
May extend from V1 to V6 and indicate larger MI
Maximal ST depression in V4 – V6 is seen more in three vessel disease and lower LVEF
Birnbaum Y,
J Am Coll Cardiol 1996;28:313-318.
Can occur both in RCA and Cx artery invt
Absence indicates RCA
ST depression in anterior leads
Isolated ST depression – Cx occlusion with a true PWMI or nonocclusive myocardial ischemia
Max ST depression in V2 and V3 is predictive of Cx
V7 –V9 shows ST elevation
True PWMI
ST depression in V1, R/S >1, and upright T wave
V1 V9
AV conduction disturbances
AV nodal delay and block occurs with proximal RCA invt, frequently with RVMI
Higher in-hospital morbidity & mortality
Sub AV conduction disturbances
RBBB with or without hemiblock during acute AWMI indicates proximal LAD
BBB or CHB indicates poor prognosis
LAHB in acute IWMI indicates additional LAD disease
LEFT MAIN STEM OCCLUSION OR TRIPLE VESSEL DISEASE
Acute LMCA occlusion rare but causes serious hemodynamic deterioration
More commonly, subtotal occlusion occurs with collaterals filling from RCA presents as Unstable angina
ECG of subtotal occlusion similar to triple vessel disease
LEFT MAIN STEM OCCLUSION OR TRIPLE VESSEL DISEASE
Marked downsloping ST depression in I, II, and V4 – V6 and STE in aVR
aVR STE occurred more in LMCA than in LAD
V1 STE was less in LMCA than LAD
High mortality rate in those with higher STE in Avr Yamaji H et al J Am Coll Cardiol 2001;38:1348-1354
Atrial infarction
Signs of atrial MI are seen in PTa segment
PTa segment elevation occurs in I, II, III, V5 or V6 or a depression in precordial leads
Occurs in 10 % of inferoposterior MI
Isolated occurrence is rare
Proximal RCA or Cx
RCA vs LCX
Limitations
Assessment of the site of occlusion of coronary vessel by ECG is most reliable in case of 1st MI
Impaired – Multivessel disease– Collateral circulation– When ventricular activation is prolonged as in
• LVH • Preexistent LBBB• Preexcitation • Paced rhythm
REFERENCE
Bayes de Luna, Antman - The 12 lead ECG in STEMI
Hein J J Wellens, Anton P M Gorgels, Pieter A Doevendans: The ECG in Acute Myocardial Infarction and Unstable angina – diagnosis and risk stratification
Y .Birnbaum Bj Drew – Ecg in STEMI - correlation with coronary anatomy and prognosis
YAMAJI H - Prediction of acute left main coronary artery obstruction by 12-lead electrocardiography. ST segment elevation in lead aVR with less ST segment elevation in lead V(1)