Repolarisation abnormalities

Figures 4.55 and 4.56 are examples of hyper-kalaemia and hypothermia that may also present ST-segment elevation in some leads. An ST-segment elevation may also be seen in other situations (Table 4.3), such as certain ionic or metabolic disorders, pneumothorax, etc., and, obviously, in secondary repolarisation abnormalities, such as mirror patterns (e.g. in V1-V2 in LVE or in LBBB).

Occasionally, the presence of an intermittent RBBB (Figure 4.66) or LBBB (Figure 4.67) allows for the visualisation of the underlying repolarisation abnormality, such as ST-segment deviation (Figures 4.66 and 4.67) or a negative T wave (Figures 3.34 and 3.41). Therefore, the evidence that... 

With respect to chronic repolarisation abnormalities, the negative T wave is more symmetric than that in the isolated complete LBBB (Figures 3.40 and 1.58). In clinical practice positive T wave in V5 and V6 is usually seen when the LBBB is not too advanced, and septal repolarisation does not predominate completely over left-ventricular repolarisation. In some cases it may be the expression of changes of repolarisation polarity induced by ischaemia. 

Figure 8.13 (1) The three types of repolarisation abnormalities that may be seen in an acute phase of myocardial infarction involving the inferolateral zone ...

Cases of Q-wave and non-Q-wave infarctions due to atherothrombosis have also been described in patients with coronary artery anomalies. However, often the restingECGisnormal, but repolarisation abnormalities, generally ST-segment depression, may be seen during exercise, with anginal pain (Figure 8.44). 

The ICH guideline lists the assessment of effects on blood pressure, heart rate and ECG. In vivo, in vitro and/or ex vivo evaluations, including methods for electrical repolarisation and conductance abnormalities, should also be considered. These abnormalities can be associated with risks for fatal ventricular arrhythmias called Torsade de pointes. 

Figure 3.27 The mixed repolarisation changes (C) are explained by the combination of the primary changes due to ischaemia (A) and the changes secondary to the depolarisation abnormalities (e.g. LVH) (B).

Figure 3.40 (A) Acute phase of an infarction in a patient symmetrical T wave in III (mixed pattern of repolarisation with complete left bundle branch block. Note the clear abnormality) leads to the suspicion of associated...

A) tall and/or wide T waves in inferior leads (B) abnormal ST-segment elevation, with no changes of the final part of QRS (C) important ST-segment elevation and distortion of the final part of QRS. (2) The three types of repolarisation... 

Sometimes the abnormality of repolarisation is an isolated negative or flattened T wave. These patterns are probably more related with partial or total reperfusion than with active ischaemia. This may be an explanation of the best prognosis having non-Q-wave MI with negative T wave (p. 239). Furthermore, often the levels of troponine are decisive to assure that an ACS has evolved to an MI because the ECG pattern may not give the correct answer (see Figure 8.2, and Tables 2.1 and 8.1). 

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