Significance of “reciprocal” ST segment depression: Left ventriculographic observations during left anterior descending coronary angioplasty
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ST depression
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Background Prior investigations of transient myocardial ischaemia have focused on ST depression events. Therefore, the purpose of this analysis was to determine the frequency, characteristics, and clinical significance of transient ST segment elevation in patients with acute coronary syndromes. Methods A secondary analysis from two prospective studies utilizing 12-lead ST segment monitoring was used to compare ST elevation vs ST depression events. Results Of 868 patients, 177 (20%) had 574 events (242, ST elevation; 332, ST depression). Patients with ST elevation were more likely to have single vessel coronary artery disease, whereas patients with ST depression were more likely to have triple vessel coronary artery disease. ST elevation events were of shorter duration, more often associated with chest pain, and had greater ST changes than ST depression events. There was no difference in clinical outcome between patients with ST elevation vs depression; however, those with ST events were more likely to have adverse hospital outcomes (OR, 3·67) or death (OR, 2·03) than patients without ST events. After controlling for clinical prognostic factors, transient ST events observed with continuous ST monitoring predicted hospital death independently from signs of ischaemia on the initial standard 12-lead ECG. Conclusions Transient ST elevation is nearly as prevalent as transient ST depression in patients with acute coronary syndromes. Since the vast majority of ST events are brief and otherwise clinically silent, ST segment monitoring is more efficacious in detecting ischaemic events and in predicting adverse clinical outcomes than patients' symptoms or the initial standard 12-lead ECG.
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Transient ischaemic ST segment changes were studied in 296 consecutive patients with coronary heart disease attending hospital for coronary arteriography. They underwent two channel, frequency modulated ambulatory monitoring for 24 hours. During this time 221 episodes of transient ST elevation (n = 56) or ST depression (n = 165) with a horizontal deviation of at least 1 mm lasting at least 1 min were found in 70 patients (23.6%). Only 34% of episodes were associated with pain. The duration of the episode, the heart rate at the beginning of the episode, or the extent of ST deviation were not related to the occurrence of pain. Episodes of ST elevation were of significantly shorter duration, occurred significantly more often during the early morning, and at significantly lower heart rates than episodes of ST depression. The considerable overlap between the characteristics of episodes of ST elevation and ST depression suggests that in many instances a combination of factors is responsible for transient ischaemic ST segment changes.
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Seventy four patients (66 men, eight women; mean age 54.3 years) underwent submaximal exercise testing 7-23 days (mean 10.7) after acute myocardial infarction. Follow up was a mean period of 11.3 months. When compared with patients with no exercise induced abnormality, ST segment elevation, ST shift (depression or elevation or both), ST depression, inability to complete five metabolic equivalents, and inadequate blood pressure response to exercise were predictive of subsequent cardiac events (cardiac death, left ventricular failure, recurrent myocardial infarction, angina). When the presence or absence of specific variables was assessed, only ST elevation and ST shift predicted subsequent cardiac events. The presence of exercise induced ST elevation was the only exercise test variable which predicted cardiac death. ST segment elevation was, therefore, the exercise induced abnormality which best predicted the risk of future complications.
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A61-year-old man came to the emergency department complaining of chest pain, and an electrocardiogram was recorded (Figure (Figure11). Acute inferior myocardial infarction is indicated by ST-segment elevation and broad upright T waves in leads II, III, and aVF. These changes are mirrored perfectly by reciprocal ST depression and T-wave inversion in leads I and aVL. Both indicative and reciprocal changes are striking in this electrocardiogram, but at times, reciprocal or mirrorimage changes are more easily recognized than indicative changes and are the clue to the correct diagnosis (1). Reciprocity works both ways, and reciprocal ST depression may be seen in the inferior leads in high lateral myocardial infarction when ST elevation occurs in leads I and aVL.
Figure 1
The electrocardiogram recorded when the patient arrived in the emergency department
The standard 12-lead electrocardiogram does not record from the back of the chest or the right side of the chest, and as a consequence, important information may go undetected (2, 3). The anterior chest leads (V1 through V3), however, are the reciprocals of leads on the back of the chest. Thus, early in posterior myocardial infarction when ST elevation and broad upright T waves would be recorded on the back of the chest, ST depression and T-wave inversion can be recorded in the anterior precordial leads (4). Such a reciprocal change is seen in lead V2 of this electrocardiogram.
Why is there no ST depression or T inversion in lead V1? In fact, there is ST elevation with an upright T in V1 because right ventricular infarction coexists. Its anteriorly directed current of injury obscures the changes of posterior infarction. This patient's right ventricle lies more squarely beneath lead V1 than V2, and the reverse is true for the posterior wall of the left ventricle. In the presence of changes of acute inferior myocardial infarction, ST elevation in V1 with depression in V2 is a quite specific (virtually pathognomonic), but rather insensitive, marker of right ventricular as well as posterior infarction (5).
Other electrocardiographic signs of right ventricular infarction in patients with acute inferior infarction are ST elevation in lead III exceeding that in lead II (6) and a ratio of ST depression in V2 to ST elevation in aVF of ≲50% (7). The best electrocardiographic guide to right ventricular infarction is an electrocardiogram with right precordial leads (Figure (Figure22). The electrocardiogram recorded at 12:34, after initiation of thrombolytic therapy, shows ST elevation in right precordial leads V3Rthrough V6R, indicating right ventricular infarction, and further evolution of the changes of inferior myocardial infarction in leads II, III, and aVF. Persistent ST depression is seen in V1R (left-sided V2), and T waves are upright. These reciprocal changes of ST elevation and T inversion on the back of the chest indicate further evolution of posterior infarction.
Figure 2
The electrocardiogram recorded 2 hours later during thrombolytic therapy. The precordial leads were recorded on the right side of the chest.
Small portions of the right ventricle may receive blood supply from the left anterior descending and/or left circumflex coronary arteries, but most right ventricular blood supply is from the right coronary artery. Consequently, all clinically significant right ventricular infarcts are due to occlusion of the right coronary artery, usually in its proximal portion. Such is the case in this patient, whose right coronary arteriogram, performed a week later, reveals severe narrowing proximal to any right ventricular branch except the conus branch (Figure (Figure33). The right coronary artery also gives rise to the posterior descending artery and left ventricular branches, accounting for the inferior and posterior distributions, respectively, of this patient's infarction.
Figure 3
Right coronary cinearteriograms recorded a week later in the cranial (a) left anterior and (b) right anterior oblique projections. In each, the culprit lesion is seen as an irregular, hazy narrowing (arrow) just proximal to the first of 3 right ventricular ...
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Eighty-two patients with variant angina underwent a treadmill exercise test using 14 ECG leads, and 67 also underwent exercise thallium-201 scans. The test induced ST elevation in 25 patients (30%), ST depression in 21 (26%) and no ST-segment abnormality in 36 (44%). ST elevation during exercise occurred in the same ECG leads as during spontaneous attacks at rest, and was always associated with a large perfusion defect on the exercise thallium scan. In contrast, exercise-induced ST depression often did not occur in the leads that exhibited ST elevation during episodes at rest. The ST-segment response to exercise did not accurately predict coronary anatomy: Coronary stenoses greater than or equal to 70% were present in 14 of 25 patients (56%) with ST elevation, in 13 of 21 (62%) with ST depression and in 14 of 36 (39%) with no ST-segment abnormality (NS). However, the degree of disease activity did correlate with the result of the exercise test: ST elevation occurred during exercise in 11 of 14 patients who had an average of more than two spontaneous attacks per day, in 12 of 24 who had between two attacks per day and two per week, and in only two of 31 who had fewer than two attacks per week (p less than 0.005). St elevation during exercise was reproducible in five of five patients retested during an active phase of their disease, but not in three of three patients who had been angina-free for at least 1 month before the repeat test. Twelve patients wih exercise-induced ST elevation were retested during treatment with calcium antagonist drugs; in 10 of 12, ST elevation did not occur with the second test. During a mean follow-up of 20.3 +/- 14.5 months, death or myocardial infarction occurred in three of the 25 patients with ST elevation during exercise, none of 21 with ST depression and two of 36 with no ST abnormality. We conclude that in variant angina patients, the results of an exercise test correlate well with the degree of disease activity but not with coronary anatomy, and do not define a high-risk subgroup.
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ST elevation
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ST elevation
Depression
ST depression
Precordial examination
Elevation (ballistics)
Benign early repolarization
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Conventional exercise electrocardiographic criteria usually involve patterns with a horizontal or downsloping ST segment. In the present study we present criteria based on upsloping ST segments and compared these criteria with the conventional criteria. Using upsloping ST-segment criteria, the amount of ST-segment depression at 80 msec after the end of the QRS complex is used as a parameter (ST criterion E, with a depression of 100 mV, and ST criterion F, with a depression of 200 mV). In the graded exercise test a bicycle ergometer was used. The ECG leads were CM5 and CC5. The results of exercise electrocardiography were compared with the findings from coronary arteriography. In 623 selected patients (565 males and 58 females), application of conventional ST criteria gave a sensitivity of 56% and a specificity of 94%; with application of the ST criteria E or F, sensitivity was 75% and specificity 90%. In the 58 females use of these new criteria resulted in a sensitivity of 76% and specificity of 88%. Ninety-three patients (15%) could be classified as positive exercise responders by the sole presence of an upsloping ST segment (type E or F). Sixty-eight percent of the patients with type E and 75% with type F had two- or three-vessel disease (coronary obstructions greater their or equal to 50%). We conclude that ST criteria based on upsloping ST segments significantly increase the diagnostic yield of the exercise ECG.
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Bicycle ergometer
Depression
Exercise tolerance test
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A 25-year-old man presented at the emergency department with complaints of fever and chest pain. The electrocardiogram (ECG) showed concave ST segment elevation that was not confined to any arterial territory. There was PR segment elevation in lead aVR as well as PR segment depression in leads II, V5 and V6. This was consistent with pericarditis. The electrocardiographical changes associated with pericarditis are discussed. A second case of a 64-year-old man with uraemic pericarditis with similar ECG changes is illustrated.
ST elevation
Benign early repolarization
ST depression
Elevation (ballistics)
Acute pericarditis
Depression
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Conventional exercise electrocardiographic criteria usually involve patterns with a horizontal or downsloping ST segment. In the present study we present criteria based on upsloping ST segments and compared these criteria with the conventional criteria. Using upsloping ST-segment criteria, the amount of ST-segment depression at 80 msec after the end of the QRS complex is used as a parameter (ST criterion E, with a depression of 100 mV, and ST criterion F, with a depression of 200 mV). In the graded exercise test a bicycle ergometer was used. The ECG leads were CM5 and CC5. The results of exercise electrocardiography were compared with the findings from coronary arteriography. In 623 selected patients (565 males and 58 females), application of conventional ST criteria gave a sensitivity of 56% and a specificity of 94%; with application of the ST criteria E or F, sensitivity was 75% and specificity 90%. In the 58 females use of these new criteria resulted in a sensitivity of 76% and specificity of 88%. Nine...
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Depression
Bicycle ergometer
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Objective Discuss the sensitivity of diagnostic standareds of electrocardiography about right ventricular infarction.Methods Analyse the electrocardiography of 17 cases on right ventricular infarction that had been collected.Results The ratio of the ST elevation in V4R which is no less than 0.1 mV is 35.3%;The ratio of the ST elevation in V4R which is no less than 0.05 mV is 71.1%;The ratio of the ST elevation in V3R to V6R leads which is no less than 0.1 mV is 35.3%;The ratio of the ST elevation reduced by degrees in Vl to V5 leads is 47%;The ratio of the ST elevation in Ⅲ is more than the ST elevation in Ⅱis 47%;The ratio that between ST depression in V2 and ST elevation in avf is no more than 50% is 11.1%;The Q waves in Ⅰ、avL、V5、V6 had disappeared is 53%;The ratio of AVB is 58.8%.Conclusion The sensitivity of all indicators of diagnostic diagnostic standareds of electrocardiography about right ventricular infarction is a little lower.
ST elevation
ST depression
Elevation (ballistics)
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