Anteroseptal zone

Both acute coronary syndromes (ACSs) and infarcts in chronic phase affect, as a result of the occlusion of the corresponding coronary artery, one part of the two zones into which the heart can be divided (Figure 1.14A) (1) the inferolateral zone, which encompasses all the inferior wall, a portion of the inferior part of the septum and most of the lateral wall (occlusion of the RCA or the LCX) (2) the anteroseptal zone, which comprises the anterior wall, the anterior part of the septum and often a great part of inferior septum and part of the mid-lower anterior portion of lateral wall (occlusion of the LAD). In general, the LAD, if it is large, as is seen in over 80% of cases, tends to perfuse not only the apex but also part of the inferior wall (Figures 1.1 and 1.14). 

Figure 2.2 (A) A patient with myocardial infarction of anteroseptal zone in a subacute phase (1) normal recording that displays extension of Q waves up to V6 (qrs). Small changes in the placement of precordial V3-V6 leads have significantly modified the morphology of QRS, now being qR in a lead V6. Therefore, according to the...

C) ECG-VCG correlation of the T wave and T loop in case of subepicardial ischaemia of anteroseptal zone. Observe how the T loop with homogeneous inscription (symmetric negative T wave in ECG) and a QRS loop that is directed backwards and to the left with counter-clockwise direction and the T loop backwards and to the right (see HPa). 

Figure 3.18 Acute infarction of anteroseptal zone with ST-segment elevation in the prefibrinolytic era. Evolutionary phases (A) at 30 min, (B) 1 day later, (C) 1 week later and (D) 2 weeks later.

The correlations that will be presented are based on the segmentation of the LV into two zones the anteroseptal and the inferolateral (Figure 1.14 and p. 17). The involvement of the anteroseptal zone corresponds to cases with occlusion of the LADand its branches (Table 4.1A),while the involvement of the inferolateral zone corresponds to the occlusion of the RCA and the LCX (Table 4. IB). We will study 12 different locations of coronary occlusions that define 12 areas at risk, 6 in the anteroseptal zone (Table 4.1 A) and 6 in the inferolateral zone (Table 4. IB). The ECG patterns that match with these different areas will be commented and discussed in all cases. 

From a clinical point of view, in the majority of cases, usually the most striking ECG abnormality found by the physician is ST-segment elevation located in the precordial leads (V1-V6) (anteroseptal zone) (Figure4.43) or in inferior leads (inferolateral zone) (Figure 4.45). We will see how we can identify not only the culprit artery, but also the occlusion site. 

Figure 4.66 Above (A) Acute phase of evolving Q-wave myocardial infarction of anteroseptal zone. There is a huge ST-segment elevation, especially in I, VL and from V2 to V5, QRS >0.12 s and morphology of complete RBBB that was not present in previous ECG. (B) Twenty-four hours later RBBB have disappeared and subacute anterior extensive infarction becomes evident. There is ST-segment elevation from V1 to V4. The transient presence of new...

Figure 4.67 (A) Acute Ml of anteroseptal zone due to occlusion of LAD proximal to D1 (ST-segment depression in III and VF) but distal to S1 (non-ST-segment elevation in VR and V1 and non-ST-segment depression in V6). (B) After some hours complete LBBB appears (see q in I, VL and V4 and polyphasic morphology in V3) (see the Sgarbossa...

Anteroseptal zone Q wave especially in pre-cordial leads and/or I and VL... 

Furthermore, the hemiblocks do not modify the diagnosis of MI of anteroseptal zone in precordial leads (HP), but may modify the presence or appearance of Q waves in inferior leads (inferior MI) and in VL (mid-anterior MI or extensive MI involving mid-anterior area). 

Figure 5.52 The ECG of a patient with complete LBBB and associated infarction. There are ECG criteria suggestive of extensive anterior myocardial infarction (qR in I, QR in VL and low voltage of S in V3). The CMR images (A-D) demonstrated the presence of an extensive infarction of anteroseptal zone (type A-3) (proximal LAD occlusion). The inferolateral wall is free of necrosis (see (D)), because the...

We will just remind (see p. 137) that seven areas of MI detected by CE-CMR have good correspondence with seven ECG patterns (four in anteroseptal zone - septal, apical-anterior, extensive anterior and mid-anterior - and three in the inferolateral zone - inferior, lateral and infero-lateral) (Figure 5.9 Cino et al., 2006). We have also demonstrated that in clinical practice the presence of these seven ECG patterns correlates well with the corresponding infarction areas detected by CE-CMR, and therefore these have real value in clinical practice (Bayes de Luna et al., 2006a-c) (Table 5.3). Therefore, in chronic infarction the correlation between ECG changes (Q waves of necrosis) and involved area (CE-CMR) is clearly good (88% global concordance). However, the in-farcted area of apical infarction (A-2 type), mid-anterior infarction (A-3 type) and lateral infarction (B-l type) presents the lower concordance. 

ECG pattern for subepicardialischaemia) or symmetric and usually taller-than-normal T wave with QTc prolongation (ECG pattern of subendocardial ischaemia) located in different leads according to the corresponding affected zone - anteroseptal or inferolateral (see Experimental point of view -below - and Figure 3.5). 

In the classical ECG assessment of an STE-ACS, the leads with electrocardiographic changes give to us an approximate diagnosis of the location of the injury (anteroseptal vs inferolateral zone). However not much information was given regarding what the occluded artery was, where the occlusion was located and how large the area at risk was. Therefore, for example, the classical interpretation of... 

Type and location of the ischemia due to ACS - Usually transmural and homogeneous - Located in anteroseptal (f ST Vi 2 a V3) I or VL) or inferolateral zone (t ST II, III, and sometimes I, VL, Vs and/or [ ST V,-V3. - See atypical patterns (fig 8.3) - Often not easy to locate - When ST depression is in >7 leads with elevation in VR, the injury is very extensive (circumferential) and predominantly subendocardial - non-complete occlusion of the main trunk (LMT) or proximal occlusion of LAD + LCX (equivalent) - The ischemia is regional when the ST depression is only present in a few leads (<6) - Flat or negative T wave is due to delay of repolarization that has no subendocardial predominance. 

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