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PubMed1996

Dynamic vectorcardiography for early diagnosis of acute myocardial infarction compared with 12-lead electrocardiogram. BIOMACS Study Group.

BACKGROUND: The aim of the study was to assess the diagnostic accuracy of multilead continuous vectorcardiography (VCG) for early diagnosis of acute myocardial infarction (AMI) in patients admitted to hospital because of suspicion of AMI. VCG was compared with resting 12-lead electrocardiogram (ECG) on admission. METHODS: In a multicentre study, 107 patients with chest pain (< or = 12 h) were included. The diagnosis of AMI was on the basis of World Health Organization criteria. Continuous VCG was recorded for 12-24 h and the data were evaluated blindly at 2 and 6 h of recording and after the completion of recording (12-24 h). RESULTS: AMI was diagnosed in 74 patients. The VCG recording had a diagnostic accuracy of 71% after 2 h and 86% after both the 6 h and the completed VCG recording. Compared with ECG on admission, the VCG recording after 6 h showed a significantly greater sensitivity: 86% compared with 62% (P < 0.01). In patients with non-diagnostic ECG on arrival (n = 55), VCG after 6 h had a diagnostic accuracy of 85%, a sensitivity of 82% and a specificity of 89%. CONCLUSIONS: VCG might be useful for early diagnosis of AMI, especially in patients with non-diagnostic ECG.

Electrocardiography↗

PubMed2000

On-line vectorcardiography during elective coronary angioplasty indicates procedure-related myocardial infarction.

BACKGROUND: Increased creatine kinase concentrations after elective percutaneous transluminal coronary angioplasty (PTCA) have been shown to be associated with increased late cardiac mortality. OBJECTIVE: To evaluate the potential of continuous on-line vectorcardiography during elective PTCA to identify procedure-related myocardial infarction. METHODS: Patients (n = 192, ages 58 +/- 10 years), treated with elective and initially successful PTCA, were studied using vectorcardiogram (VCG) recordings. VCG monitoring was started 5 min before start of the PTCA and was carried out during the entire procedure, for at least 30 min after the first balloon inflation. ST-segment vector magnitude (ST-VM) and ST-segment change vector magnitude (STC-VM) were monitored. RESULTS: Fifteen (7.8%) procedure-related myocardial infarctions occurred. Indicators of procedure-related myocardial infarction were maximum value of ST-VM (P < 0.001) and STC-VM (P < 0.001), total ischemic time of all ST-VM episodes (P < 0.001) and STC-VM episodes (P < 0.001). The variable most closely related to a procedure-related myocardial infarction was the maximum STC-VM value during the procedure. With an optimized cutoff value, maximum STC-VM predicts a procedure-related myocardial infarction with a sensitivity of 93%, a specificity of 59% and a negative predictive value of 99%. Patients who had a stent implanted had significantly greater VCG values (P < 0.05-P < 0.001) than the group without a stent. There was a trend (P < 0.06) to a relation between increased creatine kinase concentration and stent implantation. In patients both with and without an implanted stent, greater STC-VM values were associated with procedure-related myocardial infarction (P < 0.01). CONCLUSION: Continuous VCG monitoring during elective PTCA is a promising method for immediate detection of patients at increased risk of procedure-related myocardial infarction.

Adult↗

PubMed2001

Comparison of continuous vectorcardiography and continuous 12-lead electrocardiography of patients with unstable coronary artery disease: do they identify the same population?

BACKGROUND: Continuous vectorcardiography (cVCG) and continuous 12-lead electrocardiography (c12ECG) are important tools for assessing patients with unstable coronary artery disease. OBJECTIVE: To compare the incidences of ischemia detected by the two methods, and examine whether the patients identified belonged to the same population, with respect to various clinical variables. METHODS: Within a randomized prospective trial (FRISC II) including patients with unstable coronary artery disease, ST-segment monitoring was performed either by cVCG or by c12ECG for 24 h after admission for 1016 patients. RESULTS: cVCG and c12ECG were performed for 730 and 286 patients, respectively. Transient ischemic episodes in 253 (34.7%) patients were detected by cVCG and such episodes were detected in 91 (31.8%) patients by c12EGG. When patients in whom transient ischemic episodes had been detected by cVCG and c12ECG were compared, the groups were similar with respect to baseline characteristics, signs of myocardial damage (67.5 versus 70.5%), occurrence of exercise-induced ischemia (59.0 versus 60.0%), and presence of severe coronary lesions (57.0 versus 51.3%). CONCLUSIONS: Results of this study suggest that these two methods identify the same high-risk population, and that these patients can be considered one group when results obtained using either system are analyzed in multicenter studies. This also implies that results concerning the occurrence of episodes of resting ischemia obtained using one system may also be applicable for the other.

Adult↗

PubMed2002

Continuous vectorcardiography is superior to standard electrocardiography in the prediction of long-term outcome after thrombolysis in patients with acute myocardial infarction.

BACKGROUND: Thrombolytic therapy results in reperfusion of the occluded coronary vessel in approximately 75% of treated patients with acute myocardial infarction (AMI). Unsuccessful thrombolysis results in impaired outcome. This study was undertaken to evaluate reperfusion assessments with 12-lead standard static electrocardiography (ECG) and continuous vectorcardiography (VCG) in AMI patients treated with thrombolytic therapy, with particular emphasis on the value of these assessments in relation to long-term outcome. METHODS: ST-recovery analysis 90 and 180 min after the start of thrombolytic therapy was performed by repeated ECG and by VCG in 63 AMI patients. Median follow-up was 255 days. RESULTS: No significant differences in long-term outcome were found between patients with or without obtained reperfusion, as assessed by ECG. For VCG, we found significant elevated relative risks for experiencing death (relative risk = 11.00, confidence interval = 2.70-44.90); P = 0.0008 for the group with ST-vector magnitude recovery of less than 50% at 90 min from start of thrombolytic therapy. CONCLUSION: We demonstrated that early reperfusion assessment with VCG enables the prediction of long-term outcome and is superior to reperfusion assessment with standard static ECG in this regard. We therefore recommend continuous ischemia monitoring of AMI patients treated with thrombolytic therapy as a routine procedure.

Denmark↗

PubMed1987

Sex- and age-related normal limits for the QRS complex in vectorcardiography.

In order to provide reference values for vectorcardiography (VCG), which are relevant with regard to sex, age and available computer technology. VCG from a normal material were studied. VCG according to Frank were recorded in 159 men and 193 women, healthy and randomly selected from a defined caucasian urban population. The technique used includes noise reduction by averaging and a spatial algorithm for QRS delineation. The results are given separately for men and women and for young and old subjects. Significant differences between these groups were found to be common and of potential importance for interpretation of VCG. Discrepancies between our results and other reports on normal ranges can be explained by both different techniques used and different composition of the material studied. On the basis of our data normal limits for a number of measurements, commonly used in diagnostic criteria for myocardial infarction and ventricular hypertrophy are reported.

Adult↗

PubMed2000

Prognostic role of on-line vectorcardiography as regards repeat revascularization after successful coronary angioplasty.

This study evaluated the prognostic significance of continuous on-line vectorcardiography (VCG) during elective coronary angioplasty (percutaneous transluminal coronary angioplasty, PTCA). Patients (n = 192, mean age 58 +/- 10), treated with elective and initially successful PTCA, were included. VCG monitoring was started before start of the PTCA procedure and was carried out during the entire procedure. ST vector magnitude (ST-VM) was monitored. A 6-month follow-up was obtained. Main outcome measures were the frequency of cardiac events and revascularization during follow-up. During follow-up, 1 patient died, 6 suffered a nonfatal myocardial infarction and 50 were revascularized. Angiography revealed restenosis in 88% of the patients who had a revascularization. In the total patient group, the VCG predictor of revascularization was the total ischemic time of all ST-VM episodes (p = 0.05). Clinical predictors of revascularization were diabetes mellitus (p < 0.01), a more severe type of lesion (type B; p < 0.01), percent post-PTCA stenosis (p < 0.05), nominal balloon size (p < 0.01), maximum balloon pressure (p < 0.05) and no stent implanted (p < 0.001). In a multivariate analysis all the above significant univariate variables of revascularization were entered. Total ischemic time of ST-VM (p < 0.01) was the best variable giving independent prognostic information. In the nonstent group, total ischemic time of ST-VM (p < 0.01) was the only independent predictor of a further revascularization. In conclusion, VCG monitoring during elective PTCA gives on-line information that identifies patients at an increased risk of a revascularization during 6 months after the initial procedure.

Angioplasty, Balloon, Coronary↗

PubMed2000

Prognostic value of ischemia monitoring with on-line vectorcardiography in patients with unstable coronary artery disease.

AIM: The aim of this study was to determine whether on-line vectorcardiography (VCG) gives independent prognostic information, regarding death, myocardial infarction (MI), and revascularization in patients with unstable coronary artery disease, i.e. unstable angina or non-Q-wave MI. METHODS AND RESULTS: One hundred and fifty patients (mean age 69 +/- 10), participating in a randomized study of low-molecular-weight heparin in unstable coronary artery disease, were studied with on-line VCG recordings for 24 h. During a 5-6-month follow-up, 11 patients died, 14 suffered a nonfatal MI and 31 were revascularized. Univariate predictors of death were diabetes mellitus (p < 0.01), maximum ST vector magnitude (ST-VM; p < 0.001), maximum ST change vector magnitude (STC-VM; p < 0.001), number of ST-VM (p < 0.01) and STC-VM episodes (p < 0.001). In multivariate analysis, the number of STC-VM episodes (p < 0.01) and diabetes mellitus (p < 0.02) each gave independent prognostic information regarding death. When all cardiovascular events were combined, the inability to perform an exercise test (p < 0.05), maximum value of ST-VM (p < 0.01) and STC-VM (p < 0.001), the number of episodes of STC-VM (p < 0.001) and ST-VM (p < 0.001) all gave prognostic information. In multivariate analysis, the inability to perform an exercise test and the number of STC-VM episodes were independent predictors. CONCLUSION: VCG monitoring during the first 24 h of hospitalization for unstable coronary artery disease gives independent prognostic information.

Adult↗

PubMed2000

A technical approach for optimizing surveillance of patients with unstable coronary syndromes: continuous vectorcardiography ischemic monitoring.

Continuous vectorcardiography ischemic monitoring (VCG) is a noninvasive technique which has contributed much to our understanding of the dynamics of acute coronary syndromes. For risk assessment of patients with unstable angina pectoris or non-Q-wave myocardial infarction, VCG shows important prognostic power which is further enhanced by its combination with the measurement of highly sensitive and specific biochemical markers of myocardial injury. VCG surveillance after revascularization therapy of Q-wave myocardial infarction is widely accepted because of its potential of assessing vessel patency, of estimating infarct size, and of revealing residual myocardial ischemia. Valuable prognostic information is available in real time with VCG, and treatment strategies may be based upon more reliable grounds. In this survey, the VCG technique is presented together with the most frequently used vectorcardiographic variables. Further, the use of the method for risk stratification of patients with unstable coronary syndromes is also described.

Electrocardiography, Ambulatory↗

PubMed1992

Continuous vectorcardiography in patients with chest pain indicative of acute ischemic heart disease.

To assess the clinical usefulness of continuous on-line vectorcardiography (VCG), we studied 61 patients admitted to the coronary care unit (CCU) with chest pain, supposedly ischemic. Continuous VCG was performed for 24 h, monitoring QRS vector difference (QRS-VD), ST-change vector magnitude (STC-VM) and ST vector magnitude (ST-VM) measured 20 and 60 ms after the termination of the QRS complex. The patients were divided into four groups based on the final diagnosis; group A, 15 patients with normal exercise tests and extracardiac causes of chest pain; group B, 15 patients with unstable angina; group C, 15 patients with non-Q-wave myocardial infarction (MI); group D, 16 patients with Q-wave MI. Treatment was given according to a normal routine. Of 31 patients with MI, 16 received treatment with streptokinase. Groups A and B showed no significant permanent changes in QRS-VD, STC-VM or ST-VM. However, group B showed a higher occurrence of transient episodes (duration: 2 min-6 h) of a significant change of QRS-VD by > 15 microVs and of STC-VM, ST-VM 20 and ST-VM 60 by > 0.1 mV. Groups C and D showed both permanent changes and transient episodes for the studied vector parameters. Transient episodes were significantly fewer in group D than in group B. In patients with MI, the permanent change of vector parameters evolved more rapidly and reached a plateau earlier in those treated with streptokinase (QRS-VD: 178 +/- 82 vs. 293 +/- 100 min, p < 0.001; ST-VM 20: 142 +/- 75 vs. 293 +/- 89 min, p < 0.005). The magnitude of the end value for QRS-VD correlated with infarct size estimated by the maximal value of creatine kinase (r = 0.89; p < 0.001). We conclude that in patients admitted to the CCU with chest pain, continuous VCG monitoring early differentiates patients suffering from ischemic heart disease (IHD) from patients without IHD. It also differentiates patients with unstable angina from patients with MI.

Adolescent↗

PubMed1995

Prognostic information from on-line vectorcardiography in unstable angina pectoris.

The prognostic information from 24-hour monitoring with on-line vectorcardiography (VCG) was assessed in 100 patients with a clinical diagnosis of unstable angina pectoris. ST change vector magnitude, ST vector magnitude and QRS vector difference were monitored. During a follow-up period of 343 +/- 77 days, 7 patients died from cardiac causes and 8 patients had a nonfatal myocardial infarction (MI). Thirty patients were readmitted for unstable angina pectoris and 36 were revascularized because of medical refractory angina. Univariate predictors of cardiac death or nonfatal MI included greater age, rest pain during hospitalization, previous MI, diabetes mellitus and high incidence of supposedly ischemic transient ST and QRS vector changes. In multivariate analysis, a high incidence of transient ST (p < 0.01) and QRS (p < 0.01) vector changes provided additional prognostic information beyond that of clinical and exercise test data. In conclusion, VCG monitoring during the first 24 h of hospitalization for unstable angina pectoris identifies patients with increased risk of adverse cardiac events.

Aged↗

PubMedDate not supplied

On-line computerized vectorcardiography: influence of body position, heart rate, radiographic contrast fluid and myocardial ischemia.

UNLABELLED: On-line computerized vectorcardiography (cVCG) is increasingly being used for continuous monitoring of myocardial ischemia, however, little is known about factors other than ischemia causing electrocardiographic abnormalities. This paper describes how three important cVCG parameters, STC-VM, ST-VM and QRS-VD, are affected by different body positions, myocardial ischemia, contrast injection and increasing heart rate in patients with and without coronary artery disease. The main findings of the study are: contrast injection and different body positions caused major changes in QRS-VD but affected ST-VM and STC-VM to a minor degree. Increasing heart rate by atrial pacing produced substantial changes in all three parameters. Ischemia during angioplasty also produced changes in all three parameters, STC-VM being the most sensitive parameter. IN CONCLUSION: (1) STC-VM (> or = 50 microV) is the most valuable parameter for monitoring ischemia; (2) we propose ST-VM > or = 50 microV as criterion instead of previously used 25 microV; (3) QRS-VD cannot be used as a single marker of ischemia, and (4) electrocardiographic changes induced by increased heart rate should be taken into account during interpretation.

Adult↗

PubMed1983

Quantitative assessment of myocardial ischemia and necrosis by continuous vectorcardiography and measurement of creatine kinase release in patients.

The accuracy of the use of the maximal QRS vector difference to estimate myocardial infarct size irrespective of infarct location was compared with that of measurement of cumulative creatine kinase (CK) release. Sixty patients with acute myocardial infarction and a history of symptoms of less than 4 hr duration were followed for 24 to 72 hr with orthogonal vectorcardiography and CK release analysis. Spatial QRS vector differences were calculated between the first QRS complex recorded and subsequent QRS complexes at timed intervals. The QRS vector difference increased rapidly and reached a plateau at an average 12.1 hr after onset of symptoms, as compared with 34.0 hr for the cumulated CK release. In 42% of the patients a stepwise progression of infarct evolution was observed. Irrespective of infarct location the maximal spatial ST vector magnitude was related to the ultimate QRS vector difference (r = .80) and to the cumulative amount of CK released (r = .64). Furthermore, maximal QRS vector difference correlated well with the maximal cumulative CK release (r = .64) Ten patients had possible infarct expansion, as indicated by recurrent QRS changes without concomitant CK release. Fifteen patients had infarct extension that was indicated by secondary CK release and that in seven patients was associated with further QRS changes. Infarct extension caused an approximate 25% increase in infarct size. Spatial ST vector magnitude, QRS vector difference, and cumulative CK release are complementary measures in the quantification of evolving myocardial injury after acute coronary occlusion and in the determination of sequels to therapeutic interventions.

Adult↗

PubMed1995

Vectorcardiography in experimental myocardial infarction. Serial changes and correlation between QRS loop change and the infarction size.

The objectives of this study were to examine the serial vectorcardiographic changes following acute myocardial infarct and to assess the relationship between QRS loop changes and infarct size. Fifty adult male Long-Evans rats of 250-350 gm body weight were used to study experimental acute myocardial infarction induced by coronary artery ligation. Vectorcardiograms (VCG) of the Frank lead system were recorded before, and 1 day and 7 days after operation. Animals were sacrificed on the 7th day for histological quantitation of infarct area ratios. We found that (1) before operation, rats have ST elevation, probably due to early repolarization. (2) After coronary artery ligation, ECG showed characteristic dome-shaped ST elevation at 1 hr after ligation which returned to normal during the first day. Abnormal Q waves appeared thereafter. (3) After ligation, maximum QRS vector, ST vector and maximum T vector were reduced in magnitude the first day and recovered by the 7th day. The vectors tended to shift their direction to the right and to the posterior. QRS-T angle, however, widened as time went on. About half of the rats revealed changes in the inscription direction of the QRS loop and abnormal QRS morphology also appeared in about half of the ligated rats. (4) Those in whom abnormal QRS loop morphology and/or biting appeared had significantly larger infarct area ratios (p < 0.01). (5) Change in QRS loop inscription direction seemed not to be related to the infarct size. (6) In the LS plane, the difference in max QRS vector magnitude between the 1st and 7th days significantly correlated with the infarct area ratio (r = 0.533, p < 0.05). In the H plane, the change in the max QRS vector magnitude at the 7th day correlated with the infarct area ratio (r = -0.531, p < 0.05). In the F plane, changes in the direction of the max QRS vector were significantly correlated to the infarct area ratio both on the first (r = 0.431, p < 0.05) and 7th days (r = 0.531, p < 0.05). It is concluded that the VCG, like the ECG, had evolutional changes in AMI and that the QRS loop seen on vectorcardiography has only a slight correlation with the histological myocardial infarct size.

Animals↗

PubMed2000

Clinical value of vectorcardiography, Holter monitoring and quantitative electrocardiology. Belgian Society of Cardiology. Working Group on Electrocardiology, Exercise Testing and Cardiac Rehabilitation.

This a position paper of the Working Group on Electrocardiology, Exercise Testing and Cardiac rehabilitation of the Belgian Society of Cardiology (BSC), aimed at reassessing the value for the clinical practice of cardiology of some electrocardiological techniques such as vectorcardiography and Holter monitoring in the frame of what has been called "quantitative electrocardiology". This official statement issued on behalf of the BSC was deemed necessary because of several consecutive attempts to discredit the clinical merits of these electrocardiological techniques currently in use in our country. This paper will also reassess the role of quantitative electrocardiology amidst non-invasive diagnostic methods used for cardiac imaging.

Electrocardiography↗

PubMed1991

Continuous vectorcardiography in cardiac surgery: natural course of vector changes and relationship to myocardial oxygen uptake.

Continuous vectorcardiography was registered before and during the first 18 hours after cardiac surgery in 53 patients. QRS vector changes (QRS-VD) occurred during the operation, but no further changes were observed postoperatively. The ST vector (ST-VM) increased during the operation, and a further slight increase occurred postoperatively. Perioperative myocardial infarction occurred in three patients. Their ST-VM was higher than the average in patients without myocardial infarction, while QRS-VD did not differ from the average pattern. Twelve other patients were studied in pacemaker-induced moderate tachycardia. QRS-VD increased in proportion to heart-rate changes (rs median = 0.93, p less than 0.01). QRS-VD also correlated with myocardial oxygen uptake (rs median = 0.62, p less than 0.05). The ST-VM responses were not uniform. The data suggest that vectorcardiogram variables can provide information related to myocardial energy metabolism.

Adult↗

PubMed1999

Vectorcardiography: a tool for non-invasive detection of reperfusion and reocclusion?

In acute myocardial infarction, the perfusion status frequently fluctuates with rapid occurrences of coronary occlusion followed by myocardial ischemia. In patients with unstable angina, most episodes of ischemia are not accompanied by chest pain. In these patients it is important to be able to monitor the results of medical treatment non-invasively to establish the need for further intervention. It is not feasible to perform coronary angiography in all patients with acute myocardial infarction to evaluate patency of the infarct-related artery. Furthermore, even in a patent artery, no reflow may be present in the myocardial tissue. Angiography is therefore not the perfect golden standard to compare noninvasive ischemia monitoring with. Prognosis seems to be a better standard for comparison. This review indicates that vectorcardiography monitoring may identify myocardial reperfusion at an early stage and gives valuable prognostic information both in patients with unstable angina and acute myocardial infarction with low interobserver variability.

Coronary Disease↗

PubMed1992

[Dynamic continuous vectorcardiography].

Continuous dynamic vectorcardiography is an ideal method for monitoring patients with myocardial ischemia. The monitoring is a non-invasive and real time registration and simultaneously safe and reproducible. The method has proved valuable for describing the evolution in different ischemic heart diseases. The method measures the electric myocardial activity in three orthogonal leads and a computer calculates the different vectorcardiographic parameters for the ST- and QRS-complexes. Vectorcardiographic registration is feasible for computer analysis, because it can summarize all information in a few parameters. Using continuous registration, the different parameters can show dynamic evolution and, in this way, describe the variability during acute myocardial infarction and unstable angina pectoris. The method also made it possible to evaluate anti-ischemic treatment in patients, as for example thrombolytic therapy.

Humans↗

PubMed1989

[Diagnosis of delayed upper left ventricular activation: limits of electrocardiography and usefulness of vectorcardiography].

The electrocardiographic (ECG) diagnosis of delayed ventricular left superior activation (DVLSA) is often difficult and uncertain, even when all the criteria proposed in clinical literature are fulfilled. The vectorcardiography (VCG) always permits an accurate diagnostic evaluation because the contour of the QRS loop describes successively the various phases of ventricular depolarization. Sensitivity and specificity of ECG in diagnosing DVLSA have been calculated referring to VCG analysis. The QRS loop initial forces orientation in the frontal plane, a VCG highly reliable criterion, was considered especially significant for this purpose. The sensitivity and specificity of ECG were, respectively, 75% and 95%. Moreover, this study has confirmed the low performance of frontal plane QRS axis criterion and the necessity of polyparametric method for a correct ECG-VCG diagnosis of DVLSA. However, the VCG is more reliable than ECG in such diagnosis because it allows thoroughly to analyze QRS-loop initial forces.

Adult↗