Relationship between ST-segment elevation and local tissue flow during myocardial ischaemia in dogs.

The relationship between electrocardiographic ST-segment changes and local tissue flow recorded from idential sites in the myocardium was determined by inserting platinum electrodes into the left ventricular wall of anaesthetized dogs. Local myocardial blood flow was measured during graded coronary constriction by recording tissue hydrogen desaturation rate. In the detection of ischaemic ST-segment elevation, intramural recordings proved to be more sensitive than corresponding epicardial recordings. Significant ST-segment elevation could only be detected by reducing local myocardial flow below 50% of control; by further reduction ST-segment elevation increased in proportion to the reduction in myocardial flow. Thus, significant myocardial ischaemia might exist without electrocardiographic alterations.     

Anterior ST-segment elevation with right coronary artery occlusion: a unique case of isolated right ventricular infarction

Anterior ST-segment elevation is the classic electrocardiographic feature of anterior left ventricular myocardial infarction due to occlusion of the left anterior descending artery. However, anterior ST-segment elevation has also been described in patients with right coronary artery occlusion, in whom concomitant inferior ST-segment elevation is also typically present. A case of proximal right coronary artery occlusion resulting in anterior ST-segment elevation without inferior ST-segment elevation is reported in this article. It is hypothesized that the inferior left ventricular wall was protected by left-to-right collaterals, as seen on coronary angiography, with resultant isolated right ventricular infarction upon proximal right coronary artery occlusion. In conclusion, this report presents a unique case of an isolated right ventricular infarction resulting in an electrocardiographic pattern mimicking anterior-wall left ventricular infarction.     

急性前壁心肌梗塞下壁导联ST段压低的临床意义

对44例急性前壁心肌梗塞患者,将冠脉造影结果与体表心电图ST段改变进行比较分析.结果发现急性前壁心肌梗塞患者38.6%有下壁导联ST段压低,这些导联ST段压低与多支血管病变无关,而与前降支近端病变有关,可能反映高侧壁导联心肌缺血时心电图对应性改变.     

Association of transient abnormal Q-waves during exercise testing with a stenosis of the main stem of the left coronary artery

Transient electrocardiographic changes resembling acute myocardial infarction, with Q-waves and ST-segment elevation, have been reported in a variety of clinical situations in which evidence for acute myocardial necrosis was not apparent. Such electrocardiographic changes resolved to normal within minutes. We report a case in which exercise testing induced a painless reversible electrocardiographic abnormality identical to acute anterior myocardial infarction, and subsequent angiography revealed a severe stenosis in the proximal left coronary artery. We suggest that patients presenting with this type of electrocardiographic exercise response should proceed to urgent coronary angiography.     

Value of the electrocardiogram in predicting left ventricular enlargement and dysfunction after myocardial infarction

To identify electrocardiographic predictors of left ventricular enlargement or persistent dysfunction following a myocardial infarction.Baseline and predischarge 12-lead electrocardiograms (ECGs) from 272 patients with anterior myocardial infarction who were enrolled in the Healing and Early Afterload Reducing Therapy trial were evaluated and related to echocardiographic data obtained at baseline and day 90. ST-segment elevation, QRS score, and number of negative T waves were assessed at both time points. The majority of patients (87%; n = 237) received reperfusion therapy. Multivariate models were used to adjust for potential confounders, including maximal creatine kinase level and ejection fraction at baseline.None of the baseline electrocardiographic variables independently predicted ventricular enlargement or recovery of function. In contrast, the sum of ST- and maximum ST-segment elevation, and the number of leads with ST-segment elevation > or =1 mm in the predischarge ECG, were independent predictors of ventricular enlargement from baseline to day 90. Each lead with ST-segment elevation > or =1 mm was associated with 3.5 mL of ventricular enlargement (95% confidence interval [CI]: 1.6 to 5.5 mL; P <0.0001). Similarly, the sum of ST-segment elevation (odds ratio [OR] = 0.78; 95% CI: 0.69 to 0.89; P <0.0001), the maximum ST-segment elevation (OR = 0.25; 95% CI: 0.13 to 0.45; P <0.0001), and the number of leads with ST-segment elevation > or =1 mm (OR = 0.58; 95% CI: 0.45 to 0.74; P <0.0001) were independently associated with a lower likelihood of recovery of function at day 90.Predischarge ECG may be a useful tool for early identification of patients at risk of ventricular enlargement and persistent dysfunction following myocardial infarction.     

Precordial mapping of ST-segment elevation and Q waves following anterior myocardial infarction. The effects of established beta-blocking drugs.

The electrocardiographic (ECG) signs of ST-segment elevation and the development of Q was using 72-lead precordial surface mapping, and the release of creatine kinase (CK) activity has been studied in 47 patients with uncomplicated anterior myocardial infarction. These findings were compared with a further nine patients who had acute myocardial infarction but were receiving long-term beta-blocking drugs. It was found that ST-segment elevation and Q waves had rapidly changing and different natural histories and that beta-blocking drugs altered the natural history of ST-segment changes but had no effect on the pattern and time course for the loss of electrically active myocardium. There was a close relationship between the precordial area of ST-segment elevation at 2--3 h and the final development of Q waves in the patients with uncomplicated anterior myocardial infarction. No similar relationship could be found in those on beta-blocking drugs. The pattern of changes in plasma CK and its MB isoenzymes activity were similar for both groups. The relationship between early ST-segment elevation and the final area of Q waves may prove useful in clinical practice. This may not apply where beta-blocking drugs are commenced before the initial recording of ST-segment elevation.     

ST-segment resolution assessed immediately after primary percutaneous coronary intervention correlates with infarct size and left ventricular function in cardiac magnetic resonance at 1-year follow-up

Background

Little is known about the predictive value of electrocardiographic ST-segment resolution (STR) assessed immediately after primary percutaneous coronary intervention (PCI). The aim of the study was to analyze the value of STR and maximum single-lead ST-segment elevation assessed immediately after primary PCI in prediction of infarct size and left ventricular function in cardiac magnetic resonance (CMR) at 1-year follow-up.

Methods and results

A total of 28 patients with anterior wall ST-segment elevation myocardial infarction treated with primary PCI entered the study. There was a significant correlation of STR and maximum single-lead ST-segment elevation assessed immediately after primary PCI and CMR infarct size and left ventricular function after 1 year. When analyzed according to standard optimal reperfusion cutoff (70% for STR and 1 mm for single-lead elevation), both electrocardiographic parameters were also good predictors of CMR infarct size and left ventricular function after 1 year.

Conclusions

ST-segment resolution and the single-lead maximum ST-segment elevation assessed immediately after primary PCI for ST-segment elevation myocardial infarction are good predictors of infarct size and left ventricular function in 1-year follow-up.     

A case of painless myocardial injury probably caused by coronary artery spasm]

A 53-year-old male was admitted to the hospital due to electrocardiographic ST-segment elevation in V1-4 with ST-segment depression in the inferior leads, which suggested acute myocardial infarction. He had a cough and a slight fever without chest pain. Serum creatine kinase and its myocardial band were slightly elevated but creatine kinase value did not exceed twice the normal upper limit. Emergent coronary arteriography (CAG) revealed intact coronary arteries. The CAG in a chronic stage again revealed intact coronary arteries. Intracoronary administration of acetylcholine of 100 micrograms to the left coronary artery and 50 micrograms to the right coronary artery provoked diffuse spasm in the right and left coronary arteries. The electrocardiogram (ECG) during the right coronary artery spasm revealed ST-segment depression in the inferior leads with ST-segment elevation in V2 and V3, which resembled the ECG finding at the time of the patient's admission. With intracoronary isosorbide dinitrate, the spasm and ST-segment elevation were resolved. These findings strongly suggest that coronary spasm can cause myocardial injury indicated by a slight elevation of serum creatine kinase value.     

Coronary vasospasm as a potential cause of myocardial infarction and paroxysmal atrial fibrillation in a relatively young woman

Vasospasm-related myocardial infarction in young women with normal coronary arteries has infrequently been reported and vasospasm-related paroxysmal atrial fibrillation (PAF) has rarely been described. We present a 33-year-old woman with old inferior myocardial infarction and postinfarction angina at rest; the angina was accompanied by PAF and electrocardiographic ST-segment elevation in the inferior leads. Coronary angiography revealed normal coronary arteries and intracoronary acetylcholine provoked an intense and diffuse spasm of the right and left coronary artery. The spasm of the right coronary artery was associated with PAF and ST-segment elevation in the inferior leads. Frequently documented PAF, accompanied by chest discomfort and ST-segment elevation in the inferior leads, was more effectively removed with isosorbide dinitrate than with disopyramide. These data suggest that coronary vasospasm is a likely cause of myocardial infarction and even PAF, although the precise mechanism leading to PAF remains unknown.     

Dipyridamole-induced ST-segment elevation indicative of transmural myocardial ischemia--a case report

Dipyridamole nuclear myocardial perfusion test is a safe and effective alternative to exercise nuclear perfusion testing for detecting myocardial ischemia. It is the procedure of choice in selected patients who are unable to exercise adequately. Intravenous dipyridamole causes coronary vasodilation with resultant maldistribution and heterogeneity of coronary flow in the presence of significant coronary artery disease. True ischemia, causing symptoms or ST-segment depression, is uncommon, in part because there is no increase in myocardial oxygen demand. A patient in whom myocardial ischemia developed, manifested by ST-segment elevation, during dipyridamole stress testing is described. Scintigraphic images illustrated a myocardial perfusion defect, which was consistent with coronary angiographic findings. This case report addresses the importance of dipyridamole-induced ST-segment elevation, its correlation with angiographic findings, and the need for continued hemodynamic and electrocardiographic monitoring in patients following dipyridamole infusion.     

Tombstoning ST-Elevation Myocardial Infarction

Tombstoning ST elevation myocardial infarction can be described as a STEMI characterized by tombstoning ST-segment elevation. This myocardial infarction is associated with extensive myocardial damage, reduced left ventricle function, serious hospital complications and poor prognosis. Tombstoning ECG pattern is a notion beyond morphological difference and is associated with more serious clinical results.Despite the presence of a few reports on tombstoning ST elevation, there is no report which reviews STEMI demonstrating this electrocardiographic pattern.     

A common electrocardiographic finding in an uncommon presentation

Anterior ST-segment elevation is the hallmark electrocardiographic finding of acute anterior left ventricular infarction that is caused by occlusion in one of the branches of the left coronary artery. We report a case of marked ST-segment elevation in the precordial leads, with concomitant inferior ST-segment elevation that was caused by acute occlusion of the marginal branches of the right coronary artery (RCA) causing an isolated right ventricular myocardial infarction (RVMI) during coronary angioplasty. Isolated occlusion of the marginal branches of the RCA appears to be extremely rare. In the case presented, this was caused by an iatrogenic spiral dissection with subsequent stenting of the RCA. This case illustrates that diffuse ST-segment elevation in the precordial leads may occur due to the occlusion of the RCA or its branches. It is important to recognize this scenario, since the treatment of left ventricular myocardial infarction differs from that of RVMI, where maintaining adequate preload and avoiding vasodilators to preserve right ventricular stroke volume is crucial.     

Isolated spontaneous septal myocardial infarction

Isolated occlusion of the septal perforating branch of the left anterior descending coronary artery is extremely rare. As a result, little is known about its electrocardiographic manifestations compared with those of an anteroseptal myocardial infarction. We present the case of an isolated septal myocardial infarction with ST-segment elevation.     

Differentiation between left circumflex and right coronary artery occlusions: studies on ST-segment deviation during percutaneous transluminal coronary angioplasty

To distinguish between acute occlusion of the right coronary artery (RCA) and the left circumflex artery (LCx) by electrocardiography, we studied ST-segment deviation during balloon inflation in percutaneous transluminal angioplasty. The composite electrocardiographic criteria based on ST-segment deviations increased the diagnostic specificity: that is, the finding of inferior infarction (ST-segment elevation in leads II, III, aVF) without lateral infarction (ST-segment elevation in leads V5,6) was highly suggestive of RCA occlusion (sensitivity and specificity: 35 of 43 cases, 81.4%; and 33 of 36 cases, 91.7%), whereas ST-segment elevation in leads V5,6 (LCx: 23 of 36 cases; 63.9%, RCA: 5 of 43 cases; 11.6%) or isolated ST-segment depression in leads V2-4 (LCx: 9 of 36 cases; 25.0%, RCA: none of 43 cases) was highly suggestive of LCx occlusion. These results indicate that the composite electrocardiographic criteria were useful in predicting the artery involved in acute myocardial infarction, although any single criterion was not sensitive or specific enough to differentiate right from left circumflex coronary artery occlusion.     

“Intermittent” and transient ST-segment elevation following direct current cardioversion

Transient ST-segment elevation immediately following direct current cardioversion is a clearly documented occurrence in a small percentage of cases. Two main explanations have been suggested: myocardial injury or coronary vasospasm. We report two cases of “intermittent” and transient ST-segment elevation after cardioversion. Such intermittent elevation of the ST segment has not been reported previously. We hypothesize that this electrocardiographic observation is explained by a timing difference induced by electroshock in the action potential between the epicardium and endocardium.     

Left ventricular apical rupture caused by takotsubo cardiomyopathy--comprehensive pathological heart investigation.

An 81-year-old woman with emotionally-induced takotsubo cardiomyopathy developed a fatal left ventricular (LV) apical rupture. During the hospitalization persistent ST-segment elevation with no electrocardiographic time evolution was observed on the ECG, characteristic for takotsubo cardiomyopathy. Histopathologically, transmural myocardial necrosis with hemorrhage was found at the rupture site, but there were foci of coagulation and contraction band necrosis with mononuclear lymphocyte infiltrations in other heart regions, and the intensity and distribution of these pathological changes corresponded to the distribution of the LV contraction abnormalities seen on ventriculography. The article concludes that: the LV functional disorder in takotsubo cardiomyopathy may be caused by distracted foci of coagulation and contraction band necrosis in the myocardium; contraction band necrosis (a sign of catecholamine cardiotoxicity) may reflect the sympathetic hyperactivity in this disease; persistent myocardial damage expressed by persistent ST-segment elevation without an electrocardiographic time evolution should be carefully observed with sequential echocardiographic examinations because of the possibility of cardiac rupture.     

Electrocardiographic and segmental wall motion abnormalities in pancreatitis mimicking myocardial infarction

Transient electrocardiographic changes in patients with acute cholecystitis, pancreatitis, and pneumonia have been reported in the past.^1-5 These changes usually are in the form of T-wave inversion, ST-segment depression, and rarely ST-segment elevation in the absence of coronary artery disease.^1-5 To the authors' knowledge, this is the first report documenting both left ventricular segmental wall motion abnormality and electrocardiographic changes of myocardial injury in the presence of acute pancreatitis.     

Electrocardiogram patterns in acute left main coronary artery occlusion

Acute coronary syndrome with subtotal occlusion of the left main coronary artery is rather frequently encountered in the catheterization laboratory, whereas survival to hospital admission of sudden total occlusion of the left main coronary artery is rare. The typical electrocardiographic (ECG) finding in cases with preserved flow through the left main is widespread ST-segment depression maximally in leads V4-V6 with inverted T waves and ST-segment elevation in lead aVR. In acute myocardial ischemia without (or with minor) myocardial necrosis, the ECG pattern is transient, whereas persistent ECG changes, usually without development of Q waves, are indicative of myocardial injury. In acute total left main occlusion, severe ischemia may be manifested in the ECG by life-threatening tachyarrhythmias, conduction disturbances, and ST-segment deviation. Because of the potential for life-saving therapeutic options by invasive therapy, the ECG markers of the serious condition should be recognized by the medical profession. Left main occlusion should be suspected in severely ill patients with widespread ST-segment depressions, especially in leads V4-V6 with inverted T waves or ST elevation involving the anterior precordial leads and the lateral extremity leads I and aVL. In addition, lead aVR ST elevation accompanied by either anterior ST elevation or widespread ST-segment depression may indicate left main occlusion.