Vectorcardiographic monitoring of patients with acute myocardial infarction and chronic bundle branch block

A NOVEL METHOD TO ISCHEMIC HEART DISEASE DETECTION BASED ON NON-INVASIVE ECG IMAGING

Electrocardiogram (ECG) signals containing very important information about the cardiac are one of the most common tools for physicians in the diagnosis of various types of cardiac diseases. Low accuracy in positioning, limitation of time accuracy, the similarity of signals between some diseases and normal signals and probability of missing some aspect of data are the defect aspects of this method. Importance of cardiac signals and defects of current methods in diagnosis show the need of substituting a new method to show the activity of cardiac. One of the most dangerous defections is ischemia, which corrects and on time diagnose could avoid the latter effect of it. Each of common methods for diagnosis of this illness has their own advantages and disadvantages. In this paper, we consider describing a non-invasive method for ischemic episode detection based on mapping of ECG signals. With this method, we can present the signals with virtual colors and facilitate the diagnosis of ischemic disease. So, a new method of 12-lead cardiac presentation is described that in fact present the 12-lead signals in two images. The result of this paper will present the indicators of sensitivity, specificity and accuracy in the context of disease diagnosis. This paper proposed a novel ECG imaging algorithm for classifying the normal and ischemic signals and 95.35% specificity, 96.79% sensitivity and 95.76% accuracy were achieved which are very much promising compared to the other methods and doctor’s accuracy.

A new way of quantifying diagnostic information from multilead electrocardiogram for cardiac disease classification

A new measure for quantifying diagnostic information from a multilead electrocardiogram (MECG) is proposed. This diagnostic measure is based on principal component (PC) multivariate multiscale sample entropy (PMMSE). The PC analysis is used to reduce the dimension of the MECG data matrix. The multivariate multiscale sample entropy is evaluated over the PC matrix. The PMMSE values along each scale are used as a diagnostic feature vector. The performance of the proposed measure is evaluated using a least square support vector machine classifier for detection and classification of normal (healthy control) and different cardiovascular diseases such as cardiomyopathy, cardiac dysrhythmia, hypertrophy and myocardial infarction. The results show that the cardiac diseases are successfully detected and classified with an average accuracy of 90.34%. Comparison with some of the recently published methods shows improved performance of the proposed measure of cardiac disease classification.

Limited prognostic value of noninvasive assessment of reperfusion by continuous vectorcardiography in an unselected cohort of patients with acute ST-elevation myocardial infarction treated with thrombolysis

AIMS

We studied the prognostic value of different reperfusion criteria of short-term continuous vectorcardiography (VCG) in an unselected cohort of 400 patients with ST-elevation myocardial infarction, treated at 4 coronary care units in Stockholm, Sweden, between 1999 and 2002. The main outcome measure was 1-year mortality.

RESULTS

Of 400 study patients, 41 (10.2%) died within 1 year. One-year mortality in patients without reperfusion at 90 minutes, defined as ST resolution below 50% on VCG, was 11.6% compared with 9.0% in patients with reperfusion, (P = 0.4). Ninety-eight (24.5%) patients underwent intervention before discharge and percutaneous coronary intervention or coronary artery bypass grafting or both during the index admission. Percutaneous coronary intervention or coronary artery bypass grafting was related to improved 1-year survival (97 +/- 2% vs 87 +/- 2%, P = .0076). ST-vector magnitude resolution at 90 minutes was lower in patients who underwent intervention (P = .045). None of the reperfusion criteria of VCG was significantly associated with 1-year mortality.

CONCLUSION

Our results show that noninvasive assessment of reperfusion by continuous VCG has limited prognostic value in unselected patients treated with thrombolysis because of ST-elevation myocardial infarction when subsequent revascularizations are performed. However, VCG might be useful in selecting patients for coronary angiography with subsequent revascularization.

Continuous ST-segment monitoring of patients with right bundle branch block and suspicion of acute myocardial Infarction

BACKGROUND

Patients with right bundle branch block comprise 5-9% of all patients with acute myocardial infarction. In spite of this, limited data exist on early diagnosis or the usefulness of continuous electrocardiographic monitoring in these patients.

METHODS

A prospective multicenter study with 14 Swedish coronary care units. Patients with right bundle branch block and suspicion of acute myocardial infarction with less than 6 hours symptom duration were included. All patients were monitored with continuous vectorcardiography for 12-24 hours.

RESULTS

Seventy-nine patients were included, 43% had acute myocardial infarction. Patients with acute myocardial infarction had significantly higher initial ST-vector magnitude values (P = 0.0014) compared to patients without acute myocardial infarction. Patients with acute myocardial infarction also showed gradual regression of ST-vector magnitude over time that was not seen for patients without acute myocardial infarction (P = 0.005). ST-vector magnitude measured at the J-point differentiated best between patients with and without acute myocardial infarction. A cutoff value of 125 microV for initial ST-vector magnitude resulted in 55% sensitivity and 87% specificity for the diagnosis of acute myocardial infarction. Over time, patients with acute myocardial infarction showed greater changes in QRS-vector difference compared to patients without acute myocardial infarction (P = 0.052).

CONCLUSION

Vectorcardiographic monitoring shows good diagnostic abilities for patients with right bundle branch block and clinical suspicion of acute myocardial infarction and could be useful for continuous monitoring of these patients.

Continuous ST-segment monitoring of patients with left bundle branch block and suspicion of acute myocardial infarction

OBJECTIVES

Patients with left bundle branch block comprise 5-9% of all patients with acute myocardial infarction. Limited data exist on the usefulness of continuous electrocardiographic monitoring of these patients. We have investigated prospectively the usefulness of real-time continuous vectorcardiography for monitoring patients with left bundle branch block and suspicion of acute myocardial infarction.

DESIGN

A prospective multi-centre study.

SETTING

Fourteen Swedish coronary care units.

SUBJECTS

Patients with left bundle branch block and suspicion of acute myocardial infarction with <6-h symptom duration were included.

MAIN OUTCOME MEASURES

All patients were monitored with continuous vectorcardiography for 12-24 h.

RESULTS

One hundred thirty-three patients were included, 47% had acute myocardial infarction. Patients with acute myocardial infarction showed a marked relative decrease in ST-vector than those without (P = 0.0002). These changes were most marked in the first 90 min. When comparing patients with acute myocardial infarction receiving thrombolytic therapy or not, those treated with thrombolytics showed more marked decline in ST-vector magnitude (P < 0.0001) and in shorter time (P = 0.0017). All patients showed STC-vector magnitude changes that were more marked in patients with acute myocardial infarction (P = 0.0002). An STC-vector magnitude cut-off value of 65 microV after 90 min of monitoring gave 54% sensitivity and 72% specificity for diagnosis of acute myocardial infarction.

CONCLUSION

Real-time continuous vectorcardiographic monitoring of patients with left bundle branch and suspicion of acute myocardial infarction shows significant differences between those with and without acute myocardial infarction and could be of use for early diagnosis and subsequent monitoring.

Diagnosis of acute myocardial infarction in patients with chronic left bundle-branch block. Standard 12-lead ECG compared to dynamic vectorcardiography

Standard 12-lead electrocardiogram (ECG) criteria were evaluated and compared with dynamic vectorcardiography for diagnosing acute myocardial infarction in 33 patients with chronic left bundle-branch block. In 14 patients a clinical diagnosis of acute myocardial infarction was made, but it was found that none of the seven most promising ECG criteria suggested in the literature could alone or in combination diagnose acute myocardial infarction. QRS vector difference evolution showed the same kind of pattern as that for patients with narrow QRS-complex. By using a predefined specific pattern, a diagnostic accuracy of 79% was achieved. The results indicate that dynamic vectorcardiography is a better tool for diagnosing and monitoring acute myocardial infarction in patients with left bundle-branch block than standard 12-lead ECGs taken on admission and after 12-24 h.

Bundle-branch block in a general male population: the study of men born 1913

BACKGROUND

Interest in bundle-branch block has focused primarily on its role as a predictor of mortality and coexisting cardiovascular diseases. Previous studies of prevalence, correlation to cardiovascular disease, and mortality have produced conflicting results.

METHODS AND RESULTS

We studied a random-sampled population of 855 men who were 50 years old in 1963 and followed them up for 30 years with repeated examinations. Men who developed bundle-branch block were studied with regard to cumulative incidence, relationship with cardiovascular disease/risk factors, and survival. The prevalence of bundle-branch block increases from 1% at age 50 years to 17% at age 80 years, resulting in a cumulative incidence of 18%. No significant relationship with ischemic heart disease or mortality was found. Men who would develop bundle-branch block had a bigger heart volume at age 50 years and developed diabetes mellitus and congestive heart disease during follow-up more often than control subjects.

CONCLUSIONS

Bundle-branch block correlates strongly to age and is common in elderly men. Our results support the theory that bundle-branch block is a marker of a slowly progressing degenerative disease that also affects the myocardium.