Analysis Of ST Segment Changes Research Articles

ST-segment changes in high-resolution body surface potential maps measured during exercise to assess myocardial ischemia: a pilot study.

IntroductionThe aim of the study was to assess myocardial ischemia by analysis of ST-segment changes in high-resolution body surface potential maps (HR-BSPM) measured at rest and during an exercise stress test.Material and methodsThe study was carried out on a group of 28 patients with stable coronary artery disease and 15 healthy volunteers. The HR-BSPM were measured at rest and during the exercise stress test on a supine ergometer. The workload was increased in stages by 25 W every 2 min, beginning at 50 W. The maps of ST-segment depression (ST60) were calculated from time averaged recordings at rest and at maximal workload.ResultsThe efficiency in detection of myocardial ischemia was higher for HR-BSPM than for standard 12-lead electrocardiography (ECG) when both methods were evaluated by outcomes of coronarography. The sensitivity of HR-BSPM was 82.4% while for the standard 12-lead ECG exercise stress test it was 58.8%. For some patients significant changes in the ST segment were observed at stress HR-BSPM but were not visible in standard 12-lead ECG recorded under the same conditions.ConclusionsObtained high values of sensitivity and specificity in myocardial ischemia detection suggest that maps of ST60 calculated from HR-BSPM can improve detection of patients with ischemic heart disease in comparison to the standard electrocardiographic exercise stress test examinations.

Relation between ST-segment changes and myocardial perfusion evaluated by myocardial contrast echocardiography in patients with acute myocardial infarction treated with direct angioplasty

The aim of this study was to evaluate the relation between myocardial perfusion and ST-segment changes in patients with acute myocardial infarction treated with successful direct angioplasty. Thirty-seven patients, successfully treated with direct angioplasty, underwent myocardial contrast echocardiography before and after angioplasty. The sum of ST-segment elevation divided by the number of the leads involved (ST-segment elevation index) was calculated at 1, 5, 10, 20, and 30 minutes after restoration of a Thrombolysis In Myocardial Infarction trial grade 3 flow. After recanalization, myocardial reperfusion within the risk area was observed in 26 patients, whereas a no-reflow phenomenon occurred in 11. In patients with myocardial reperfusion, the ST-segment elevation index progressively declined, whereas in patients with no reflow, no significant change was observed. Reduction of ≥50% in the ST-segment elevation index occurred in 20 of the 26 patients with reflow and in 1 of the 11 with no reflow (p = 0.0002). An additional increase of ≥30% in the ST-segment elevation index occurred in 3 patients with reflow and in 7 with no reflow (p = 0.003). Sensitivity, specificity, positive and negative predictive values, and accuracy of the reduction in the ST-segment elevation index for predicting microvascular reflow were 77%, 91%, 95%, 62%, and 81%, respectively. The corresponding values of the increase in ST-segment elevation index for predicting no reflow were 64%, 88%, 70%, 85%, and 81%, respectively. In conclusion, after successful angioplasty, different patterns of myocardial perfusion are associated with different ST-segment changes. Analysis of ST-segment changes predicts the degree of myocardial reperfusion.

Value of analysis of ST segment changes during tachycardia in determining type of narrow QRS complex tachycardia

Objectives. Repolarization changes during narrow QRS complex tachycardia were analyzed to differentiate the tachycardia mechanism and to guide the preliminary location of the accessory pathway.Background. Noninvasive determination of the mechanism of tachycardia is becoming increasingly important in view of the role of catheter ablation techniques for the cure of supraventricular tachycardia.Methods. We analyzed 159 12-lead electrocardiograms during narrow QRS complex tachycardia to evaluate 1) the tachycardis cycle; and 2) ST segment depression or T wave inversion, or both. Each patient underwent a complete electrophysiologic evaluation.Results. There were 13 atrial tachycardias, 57 atrioventricular (AV) node reentrant tachycardias and 89 AV reciprocating tachycardias. The mean RR cycle did not differ among types of tachycardia. ST segment depression >2 mm or T wave inversion, or both, was present more often in AV reciprocating tachycardia (57%) than in AV node tachycardia (25%). The magnitude of ST segment depression was greater in AV reciprocating tachycardia than in AV node tachycardia (mean ± SD 1.3 ± 1.6 vs. 0.7 ± 0.8 mm, p < 0.005). In AV reciprocating tachycardia distinct patterns of repolarization changes and P wave configuration were associated with different sites of the accessory pathway.Conclusions. The presence of ST segment depression > 2 mm or T wave inversion, or both, durig narrow QRS complex tachycardia suggests that AV reentry using an accessory pathway is the mechanism of the tachycardia. The phenomenon may be the consequence of a distinct pattern of retrograde atrial activation. Analysis of repolarization changes can guide preliminary localization of the accessory pathway even in the absence of ventricular preexcitation.

Use of Ambulatory Electrocardiographic (Holter) Monitoring

To evaluate the clinical efficacy of ambulatory electrocardiographic (ECG) monitoring and to develop guidelines for its use in clinical practice. Studies reported since January 1978 were identified both through computer searches using Index Medicus and extensive manual searching of bibliographies of identified articles. Only studies that fulfilled methodologic criteria designed to limit bias were reviewed. Information describing population and study results was assessed in four major categories (variability, diagnosis, prognosis, and therapy guidance) for both arrhythmia monitoring and ST-segment analysis. The day-to-day variability of arrhythmia and myocardial ischemia detected by ambulatory ECG monitoring may be considerable in an individual patient. Caution must therefore be used in interpreting serial tests. Ambulatory ECG monitoring with diary correlation permits documentation of cardiac arrhythmias causing symptoms, but the diagnostic yield is low unless symptoms are frequent. Such monitoring can provide information about prognosis in patients after acute myocardial infarction. The amount of prognostic information obtained is modest and is outweighed by other measures. There is insufficient information to make conclusions about such monitoring and prognosis in other conditions. Serial ambulatory ECG monitoring may be used to assess the effect of an antiarrhythmic drug in patients with frequent and reproducible ventricular ectopy. The effect of arrhythmia suppression on survival is uncertain. Because of its low sensitivity and specificity, analysis of ST-segment changes during ambulatory ECG monitoring is inaccurate in establishing or excluding the presence of coronary disease. Although anti-ischemic interventions reduce the frequency and duration of ST-segment changes on monitoring, there are no data on the utility of using reduction or elimination of the changes as the endpoint of therapy. Ambulatory ECG monitoring can provide diagnostic, prognostic, and therapeutic information in many situations, but similar information often may be better obtained in other ways.

A system for simultaneous esophageal atrial pacing and ventricular recording in computer analysis of posterior ischemia

Abnormalities of the posterior cardiac wall are often small and obscured by electrical activity of the anterior wall of the left ventricle or by right ventricular hypertrophy. The posterior wall is hidden from the precordial leads by the anterior wall, and electrodes placed on the back are of little use because of their distance from the heart and of the intervening high-resistivity lungs. In contrast to the body surface, the esophagus provides a unique perspective of the posterior aspects of the heart at close range. The authors employed a noninvasive approach to produce cardiac stress and simultaneously record posterior cardiac electrical activity via the esophagus. A new esophageal electrode and instrumentation were developed for acquiring a high-quality esophageal electrocardiogram (ECG) during transesophageal atrial pacing stress. They present their technique for combining stress testing and computer analysis of ST-segment changes in the esophageal ECG as well as preliminary results from one normal subject and one patient with known posteroinferior ischemia.

Computerised analysis of ST segment changes in ambulatory electrocardiograms.

The TELAVIV system for computerised arrhythmia detection and identification in ambulatory ECGs has been extended to include a reliable and rapid computerised method for ST-segment analysis. It now incorporates self-learning analysis and classification of ST-segment changes. Some advantages for ST-segment analysis present in this algorithm are: (a) it analyses three channels simultaneously instead of one or two in other systems; (b) it includes a larger number of parameters describing the ST-segment changes; (c) the measurements are detected from a noise-free template, averaged over 20 beats; (d) isoelectric and J-points are detected by a self-learning process; (e) a scoring system has been added; and (f) it now has the capability to detect and classify arrhythmias and ST-segment changes simultaneously. The system was tested on three types of recordings: 30 1 h recordings in which ST-changes were observed in the quick summary plot produced by the TELAVIV system; 12 recordings taken during submaximal effort; and 13 recordings made during conventional ergometry. The results indicated a high level of sensitivity and specificity of the program.

Ischemic ST-segment changes after dipyridamole infusion

Thirty consecutive patients were studied by thallium-201 myocardial imaging after dipyridamole infusion and by coronary angiography because of syndromes of chest pain. Eight patients (27%) had ischemic ST-segment changes after the infusion of dipyridamole. They all had significant coronary arterial disease. It is suggested that the combination of visual analysis of myocardial imaging and analysis of ST-segment changes be used after dipyridamole infusion to improve the sensitivity of this non-invasive test.

Analysis of ST-segment changes in normal subjects: Implications for ambulatory monitoring in angina pectoris

Continuous monitoring of the electrocardiogram in patients with angina pectoris and coronary artery disease (CAD) has shown episodes of asymptomatic ST-segment depression, suggesting frequent silent myocardial ischemia during normal daily life. Interpretation of this new finding depends on whether similar changes occur in normal subjects. Frequency-modulated ambulatory electrocardiographic recordings were performed in 80 asymptomatic normal volunteers (20 from each decade between 20 and 50 years and, 20 more than 50 years old) and in 20 patients with noncardiac pain, negative exercise and provocative tests and angiographically normal coronary arteries. Treadmill exercise testing was performed in all subjects more than 40 years old. Episodes of T-wave change were identified in 53 subjects. Five subjects younger than 40 years had episodes of ST elevation that were prolonged; they usually occurred at night. In 3 patients they could be reproduced by postural change. Only 2 subjects, both older than 40 years had planar ST depression during tachycardia; one of these subjects had a positive exercise test response. No patient with normal coronary arteries had significant ST depression. Tachycardia was frequently associated with upsloping ST depression (36%), which was more common in younger subjects: Five subjects also showed isolated single complexes with ST depression during baseline instability. With use of frequency-modulated recordings, transient ST depression of 0.1 mV or greater that lasted 80 ms or longer and more than 30 seconds in duration, was rare in a normal population. This finding supports the use of this signal to follow the activity of CAD out of the hospital, specifically in patients with typical angina and proved CAD.

Computer system for analysis of ST segment changes on 24 hour Holter monitor tapes: Comparison with other available systems

The accuracy of a computer system that was developed for the analysis of ST segment changes recorded on Holter ambulatory electrocardiographic monitoring tapes was compared with conventional visual scrutiny, beat by beat analog printouts and a commercial J point trend system. The program calculates and plots multiple electrocardiographically derived variables in a high temporal resolution trend format. Fifty tapes of good recording quality obtained from 19 patients (13 with chronic stable angina and 6 with variant angina) were assessed visually and with the computer system; of these, 20 were analyzed by all four techniques. In the 50 tapes, 629 episodes of diagnostic ST segment changes (all true positive results) were identified by using the computer system. In contrast, only 507 were identified by visual scrutiny; none of these 507 episodes was missed by computer analysis. On the 20 tapes assessed using computer, visual, beat by beat analog and J point trend system analysis, 268, 221, 230 and 178 episodes, respectively, were documented. For the four techniques, false negative and positive results were 0, 47, 38 and 90 and 0, 10, 6 and 24, respectively. The results indicate that, of the systems assessed in this study, the computer program provides the highest accuracy for detection of transient ST segment changes. This is probably accreditable to the compact presentation of multiple electrocardiographically derived variables, allowing a detailed quantitative assessment of 24 hour tapes. It is of particular value for pathophysiologic and pharmacologic studies.