Repolarisation early

Figure 3.1 (A) and (B) show normal ST segment and T wave. (B) shows ECG with a certain ST-segment elevation but convex in respect to the isoelectric line. (C) is an example of a repolarisation pattern in case of sympathetic overdrive. (D) shows early repolarisation. (E) shows repolarisation of child s heart. (F) is rectified ST segment in...

In isolated perfused heart of different animals Janse (1982) demonstrated that ischaemia induced by the occlusion of a coronary artery produces a shortening of repolarisation in the ischaemic area during a very early and brief phase (expressed by a shortening of the TAP in this area). Nevertheless, after this very early phase, a delay in repolarisation (TAP) can be observed in the same area (Cinca et al.1980 Surawicz, 1996). Other authors have demonstrated that, when the myocardium is cooled down - equivalent to an ischaemia - the affected area (subendocardium or subepicardium) shows from the beginning a lengthening of the TAP in the cooled area (Burnes et al, 2001). 

Figure 3.11 Tall and peaked T wave not secondary to ischaemic heart disease recorded at night (Holter) in a sportsman with vagal overdrive. Note the significant bradycardia, the asymmetric T wave and the slight ST-segment elevation (early repolarisation). There is a...

Figure 4.1 Holter recording of a very young patient with early repolarisation pattern recorded at night (A) that disappeared at daytime (B). During tachycardia the repolarisation presents changes typical of sympathetic overdrive (C).

Figure 4.13 More characteristic ST-segment elevation morphologies observed in patients with ischaemic heart disease (A) and other processes (B). Type A(1) to A(6) morphologies are suggestive of acute coronary syndrome type B ST-segment elevation in other processes B(1) early repolarisation B(2) normal variant in V1 B(3) pericarditis B(4) and B(5) Brugada s syndrome (B(4) is similar to A(6)...

Figure 4.50 ECG of a young 40-year-old man. Typical example of early repolarisation (ST-segment elevation particularly evident in V2-V5 and in some leads of FP).

ST-segment elevation in many leads. ECG was considered favours the diagnosis of early repolarisation pattern. This... 

The most characteristic morphologies of ST-segment elevation in IHD and other situations are shown in Figure 4.13. The most important features that allow for differentiation of ACS from acute pericarditis, early repolarisation and dissecting aneurysm are given in Table 7.1. 

The electrocardiographic changes, when present, are of STE-ACS type and, frequently, with evolving Q-wave infarction. Furthermore, there is a risk for a false-positive diagnosis, since in the young population consuming cocaine, the pattern of early repolarisation is also frequently seen. 

Fig.i The cardiac action potential (AP) (upper panel) conventionally consists of several phases (0 ) with a duration of approximately 300 ms. Phase 0 corresponds to membrane depolarisation (Na influx), while phase 1 shows the early rapid repolarisation of the membrane. Phase 2 is the plateau of the AP (due to a reduction in Na influx and increase in Ca " influx), while phase 3 shows membrane repolarisation (resulting from the coordinated opening and closing of many different channels). Phase 4 corresponds to the resting membrane potential. The lower panels depict the currents produced by the movement of several different ions across the membrane. By convention, both the inward Na (/Na) and Ca " (/ca) ionic currents are shown downward. Several of the outward K ionic currents responsible for repolarisation are shown the delayed rectifler (lyd and the inward rectifler (7ki). Note that current amplitudes are not shown to scale... 

Of the many channels that exist in cardiac muscle, we will provide an overview of only those conductances which carry most of the outward repolarising current and that are important in understanding the basis for development of the CIPA paradigm for SP. These include only the transient outward (/to) K" current, the delayed rectifier (/r) current and its components that contribute predominantly during the plateau and early stages of repolarisation of the AP and the inward rectifier (/rir) channels. 

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