Inferior wall

It is important to obtain a baseline EKG and cardiac enzymes to evaluate the possibility of an acute myocardial infarction. The short-term (2-4 weeks) stroke risk after acute myocardial infarction (AMI) is 2.5%. Stroke is usually an early (within 14 days) complication of AMI and is more common in anterior wall (4—12%) than in inferior wall infarction (1%). Approximately 40% of patients with an anterior wall myocardial infarction develop left ventricular thrombus. 

Obtain right precordial leads in any patient with an inferior wall myocardial infarction... 

The value of SPECT viability imaging with is well established clinically with overall 70-75% accuracy for predicting recovery of LV function compared to PET [28, 29, 61, 89]. For MIBI, predictive accuracy decreases to 64% compared to PET [106, 107]. Some of these discrepancies are explained by frequent inferior wall attenuation artifacts encountered with SPECT [4, 108]. The randomized trial CHRISTMAS (Carvedilol Hibernating Reversible Ischemia) demonstrated that SPECT MIBI predicted LV functional recovery in patients receiving carvedilol [109] with LVEF improving by 3.8%, more in those patients with... 

Therefore, often, the posterior wall does not exist and for this reason, the name inferior wall seems clearly better than the name inferoposterior . On the other hand, the anterior wall is, in fact, superoanterior, as is clearly appreciated in Figure 1.1 IB. However, in order to harmonise the terminology with imaging experts and to avoid more confusion, we consider that the names anterior wall and inferior wall are the most adequate for its simplification and also, because when an infarct exists in the anterior wall, the ECG repercussion is in the horizontal plane (HP V1-V6) and when it is in the inferior wall - even in the infer-obasal segment - it is in the frontal plane (FP). 

Figure 1.12 (A) The posterior (inferobasal) wall as it was wrongly considered to be placed. With this location an infarction vector of inferior infarction (segments 4 and 10 in case of very lean individuals) faces V1-V2 and explains the RS pattern in these leads. (B, C) The real anatomic position of inferior wall (inferobasal) and lateral wall...

Figure 1.13 Sagittal-oblique view in case of normal-body-build subject (A) (G shape), in a man with horizontal heart (B) (C shape) and in a very lean subject (C) (U shape). We have found that the inferior wall does...

However, (a) infarction of the inferobasal segment (posterior wall) does not usually generate a Q wave because it depolarises after 40 milliseconds (Durrer et al., 1970) (Figure 9.5). (b) Furthermore, the CMR correlations have demonstrated that the posterior wall often does not exist, because usually the basal part of the inferoposterior wall does not bend upwards (Figure 1.13). (c) In cases that the inferoposterior wall bends upwards, even if the most part of inferior wall is posterior, as may be rarely seen in very lean individuals, as the heart is located in an oblique... 

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). 

LV is cone shaped, and, as a consequence, the four heart walls present well-defined borders at the base of the heart. However, these borders become less clear as the walls approach the apex, such that it is difficult to be sure if the infarction limited to apical area involves one or other walls. Furthermore, CMR shows that the inferobasal segment of inferior wall often does not bend upwards (Figure 1.13) thus, very fre quently all the inferior walls present the same horizontal or near-horizontal inclination. 

Furthermore, there is an inferior infarction in cases of occlusion of a large LAD artery that wraps the apex. Usually, the Q waves are only observed in leads II, III and VF when the involvement of inferior wall is equal to or greater than anterior wall (Figure 5.16). In addition, a Q wave or an ST-segment elevation in V5-V6 indicates more inferoapical than anterolateral involvement (Warner et al, 1986). 

Figure 3.10 (A) ECG with a typical pattern of chronic subepicardial ischaemia in the leads facing the inferior wall (negative T wave in II, III and VF) and the lateral wall (positive peaked T wave in V1-V2). There is a necrosis in the same area in which a QR complex in II, III and VF and an RS complex in V1 are recorded. (B) Horizontal axial...

Figures 3.18 and 3.19 show the evolution of two Mis from the acute phase with a huge ST-segment elevation until the appearance of Q wave of necrosis and negative T wave of subepicardial ischaemia. In Figure 3.20, a patient with chronic MI of inferior wall presents in the same ECG a different grade of ECG pattern of subepicardial ischaemia (negative and deep T wave in inferior leads, tall and positive T wave in right precordial leads as a mirror pattern and flat T wave in V6).

Figure 3.17 (A) and (B) ECG-VCG correlation of the T wave and the T loop of subepicardial ischaemia in two patients with myocardial infarction (A) of the inferior wall and (B) of the inferior and lateral walls. Observe that a T loop in both cases shows homogeneous inscription and is directed upwards (see FPa) in the first case and upwards and forward in the second case (see HPa). The QRS loop of (A) rotates only clockwise and of (B) rotates first clockwise and later counter-clockwise. In the first case inferior Ml is isolated and in the second, associated to superoanterior...

Figure 3.19 Evolution of inferior wall infarction due to RCA occlusion after RV branches treated with fibrinolysis. Observe the ST-segment deviations depression in lead I,...

ST elevation in precordial leads and VL ST elevation in inferior wall and/or lateral /eac/st... 

The LAD perfuses the anterior wall and the anterior portion of the septum and great part of the inferior part of the septum and portion of the mid-low anterior part of the lateral wall (see p. 17). If, as frequently occurs ( 80%), it is a long artery that wraps the apex and perfuses part of the inferior wall (Figures 1.2 and 1.14), the first diagonal branch (Dl) and the first septal branch (SI) take off from the proximal portion of the LAD. Generally, the first diagonal branch (D1) is located below the first septal branch (SI). It is the opposite in almost 10% of the cases. 

The injury vector is directed anteriorly and to the right because the injury vector faces the anteroseptal area and often downwards (occlusion distal to Dl), especially if the LAD is long and wraps the apex, affecting part of the inferior wall. Then, if the anterior wall is not greatly affected because the occlusion occurs below a big Dl, the involvement of the inferior wall can turn out to be more important than the involvement of the anterior wall. The projection of this injury vector in the positive and negative hemi-fields of different leads of FP and HP explains the ST-segment elevation from VI to V4 and... 

Figure 4.25 Above (A) STE-ACS due to LAD occlusion proximal to S1 but distal to D1. (A) The site of occlusion. (B) Myocardial area at risk. (C) Bull s-eye polar map with involved segments. (D) Injury vector directed to the right and forwards due to occlusion proximal to S1. In case of a long LAD involving also inferior wall, the vector can be directed somewhat downwards due to relatively small myocardial area of anterior wall involved in case of occlusion distal to D1. The occlusion distal to D1 explains the ST-segment elevation from V1 to V3-V4 and...

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