ST segment changes

In 34 women undergoing cesarean section at full term under spinal anesthesia, heart rate and cardiac output increased significantly within 2 minutes of the rapid administration of either 5 or 10 units of oxytocin, with an associated 10 mmHg fall in mean arterial pressure in those who received 10 units (6). There were significant ST segment changes in 11 of 26 women undergoing cesarean section, with raised concentrations of troponin I in two however, the relationship to oxytocin administration was not clear in this report (7). 

Roeske WR, Higgins C, Karliner JS, et al. 1975. Incidence of arrhythmias and ST-segment changes in elderly patients during barium enema studies. Amer Heart J 90 688-694. 

Although adenosine and ATP very commonly cause adverse effects, they are generally mild and usually transient, because adenosine is rapidly eliminated from the blood (with a half-life of less than 10 seconds). Adverse effects have been reported in 81% of patients given adenosine and 94% of patients given ATP (5). Exercise reduces the noncardiac adverse effects and the incidence of major dysrhythmias (6). Reducing the duration of adenosine infusion from 6 to 4 minutes reduced the incidence of chest discomfort and ischemic ST segment changes, but had no impact on non-cardiac effects (7). 

Later on in this book (see p. 69 and 137) we will explain all these correlations in greater detail, and we will look at the areas at risk (Table 4.1) and the areas of infarct (Figure 5.9). Due to reperfusion treatment the correlation of the ST-segment changes during an ACS with the occluded artery... 

Many aspects of the mechanism of ischaemia-induced ST-segment changes lack solid biophysical underpinning, although it has been recently demonstrated (Hopenfeld, Stinstra and Macleod, 2004) that the electrocardiologic response to... 

Thus, based on the leads showing ST-segment changes, including reciprocal changes, it is possible to know (a) the involved artery and the occlusion site, and (b)the myocardial area at risk (area with... 

In these cases it maybe useful to assess the ST/T in V4R to know whether the occlusion is located in the proximal or distal RCA or in the LCX (Figure 4.32) (Wellens, 1999). Since V4Ris sometimes not recorded and because abnormalities occurring in this lead are often quite transient, we use a sequential approach based on the ST-segment changes seen in the 12-lead surface to know weather the RCA or the LCX is the culprit artery (Fiol et al., 2004b) (Figure 4.45). 

ST-segment changes in patients with active ischaemia due to multivessel disease... 

Figure 4.9 shows how in case of LMT incomplete occlusion the circumferential diffuse subendocardial injury explains the ST-segment changes. However, we have to remind that rarely cases of critical... 

Figure 5.22 ECG patterns of acute and chronic mid-anterior Ml. (A) Acute phase shows the ST-segment elevation in I and VL with in this case mild-ST-segment depression in V3 probably due to association of LCX involvement (see ST-segment changes in patients with...

Correlation between the ST-segment changes, the occlusion site and the area at risk... 

We have already discussed (p. 101) the algorithms that give key information about how different ST-segment changes are related to the occlusion of different coronary arteries and locations (see Table 4.1, p. 70, and Figures 4.43 and 4.45). The correlation between the ST-segment elevations and depressions in the different leads has already been... 

STE-ACS global prognostic value of the ST-segment changes on admission (Birnbaum et al., 1993 Elsman et al., 2006 Hathaway, 1998a,b Morrow et al., 2000a,b)... 

In the first part (see ST-segment changes in patients with active ischaemia due to multivessel disease and p. 105) we have described the ECG characteristics that may suggest the implication of more than one vessel in the genesis of STE-ACS. Usually, in these cases, the area at risk is higher and the outcome is worst. However, in spite that in some cases it seems clear that more than one vessel actively participates in the ischaemia that induce the ACS, usually even in the presence of multivessel disease there is one culprit artery responsible for ACS. 

Figure 8.26 Other example of exercise test in a patient with ischaemic heart disease that demonstrated the presence of significant ST-segment changes in premature beats (see V3-V4) that were not so evident in normal sinus complexes.

Figure 8.41 (A) ECG of a 35-year-old multiparous woman with a very serious ACS due to occlusion of LAD proximal to D1 and S1. Observe the morphology of the advanced RBBB + SAH together with evident ST-segment changes (ST elevation in precordials - occlusion in LAD), with ST-segment depression in II, III and VF (occlusion proximal to D1), and ST-segment elevation in VR and V1 with ST-segment depression in V6 (occlusion proximal to S1). (B) The ECG patterns of the evolution through time (V1).

---