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At least 19 recordsLinked to original sources
PubMed2000

Positional changes of spatial QRS- and ST-segment variables in normal subjects: implications for continuous vectorcardiography monitoring during myocardial ischemia.

Electrocardiographic QRS- and ST-segment changes are to be expected during changes in body posture. We prospectively analyzed the influence of changes in body position on continuous vectorcardiography monitoring of QRS-vector difference (QRS-VD) and ST change-vector magnitude (STC-VM) according to the currently used criteria of myocardial ischemia in 21 normal subjects. Fifteen (71%) and 6 (29%) subjects had significant positional QRS-VD and STC-VM changes, respectively. Vectorcardiography changes were most frequent and pronounced in the left lateral position. An alternative to the existing criterion of ischemia is proposed to improve the specificity of STC-VM. Subjects with positional QRS-VD changes had higher mean STC-VM values as compared with those without such changes. Otherwise no characteristics among those with positional vectorcardiography changes could be identified. There was no statistically significant association between positional QRS-VD and STC-VM changes (R = .13, P = .57). We conclude that the clinical use of QRS-VD in its present form for continuous vectorcardiography monitoring of myocardial ischemia seems to be of limited practical value, because of the presence of frequent "pseudo-ischemic" changes. STC-VM seems to have a significant potential of continuous vectorcardiography monitoring. However, an indicator of body position change or even an algorithm enabling on-line correction for positional vectorcardiography changes seems to be essential to improve the accuracy of this technique in identifying myocardial ischemia.

Adult↗
PubMed1995

Dynamic on-line vectorcardiography improves and simplifies in-hospital ischemia monitoring of patients with unstable angina.

OBJECTIVES: This study sought to validate computerized vectorcardiography against the established technique of Holter electrocardiographic (ECG) monitoring and to compare the feasibility of the two methods for monitoring patients with unstable angina pectoris. BACKGROUND: Detection of myocardial ischemic episodes is an important objective in patients admitted to the hospital for unstable angina pectoris. Standard ECG monitoring may be sufficient for detection of symptomatic episodes but will often overlook silent ischemia. Holter ECG monitoring has a higher likelihood of discovering such episodes, but analysis is time-consuming, and the results are not available on-line. METHODS: We simultaneously monitored 53 consecutive patients with unstable angina, 46 of whom had technically adequate 24-h Holter ECGs and computerized vectorcardiograms. RESULTS: The Holter tapes had a mean (+/- SD) of 15.3 +/- 10.3 h of recording with both channels technically adequate for analysis compared with 23.7 +/- 1.77 h of vectorcardiographic recording that could be analyzed (p < 0.01). Of the 15 symptomatic episodes detected by Holter ECG monitoring, 13 were also detected with dynamic vectorcardiography. In contrast, eight patients had 18 episodes of chest pain, with simultaneous ST segment changes detected by dynamic vectorcardiography; only 9 of these episodes were also detected by Holter ECG monitoring. CONCLUSIONS: Monitoring of myocardial ischemia with dynamic vectorcardiography seems to be more efficient than Holter monitoring and may have a higher sensitivity. Computerized, continuous vectorcardiography has a complete real-time capacity, allowing monitoring over prolonged periods of time, and the results are immediately available without time-consuming analysis.

Adult↗
PubMed2003

Dynamic QRS-complex and ST-segment monitoring by continuous vectorcardiography during carotid endarterectomy.

BACKGROUND: Many authors report a high incidence of cardiac events during carotid endarterectomy. The aim of the present study was to evaluate the usefulness of dynamic continuous on-line vectorcardiography for monitoring the occurrence of myocardial ischaemia during carotid endarterectomy. METHODS: We studied 21 patients undergoing carotid endarterectomy. Patients underwent general anaesthesia with isoflurane or sevoflurane. The vectorcardiogram was monitored continuously during carotid endarterectomy. Electrodes were placed according to the previously described lead system and connected to a computerized system for on-line vectorcardiography. Two trend variables were recorded: the QRS vector difference, which reflects changes in the shape of the QRS complex; and the ST vector magnitude, which represents deflection of the ST segment from the isoelectric level. The ST segment deflection was measured 60 ms after termination of the QRS complex. RESULTS: Vectorcardiography was successfully recorded in all 21 patients. Three patients showed intraoperative vectorcardiogram abnormalities. In one of these three patients, both ST vector magnitude and QRS vector difference increased after induction of anaesthesia and ST vector magnitude returned to baseline after administration of nitroglycerin. In the other two patients, both ST vector magnitude and QRS vector difference gradually increased after cross-clamping of the internal carotid artery and ST vector magnitude returned to baseline after unclamping. QRS vector difference remained elevated for several hours in all three patients. CONCLUSIONS: Monitoring ST vector magnitude and QRS vector difference by vectorcardiography may be useful for identifying myocardial ischaemia during carotid endarterectomy.

Aged↗
PubMed2002

Computerized vectorcardiography telemetry: a new device for continuous multilead ST-segment monitoring of ambulatory patients. A preliminary report.

BACKGROUND: Continuous vectorcardiography ST-segment monitoring has become a well-established method in the surveillance of patients with acute myocardial ischemia. However, immobility of the vectorcardiography technique prevents monitoring of patients during ambulatory activities. Computerized vectorcardiography telemetry (CVT) with the capacity of real-time ST-segment analysis has been developed in an attempt to overcome this shortcoming. Recent data, however, indicate that changes in body position occasionally lead to pseudo-ischemic ST-segment changes during continuous ST-segment monitoring. AIMS: This report describes the technical features of the CVT system, presents clinical examples using CVT, and assesses the influence of changes in body position on ST-vector magnitude (ST-VM) during CVT, respectively. METHODS: Clinical cases involving CVT are presented. The influence of changing body position during CVT monitoring was evaluated on 24 patients with suspected acute coronary syndromes, i.e., unstable angina or acute myocardial infarction. Each patient performed a specific body positional schedule. RESULTS: We present three discrete clinical cases where CVT provided early and valuable evidence of ongoing myocardial ischemia. The consequences of different recumbent and ambulatory body positions on ST-VM during CVT monitoring appear to be limited. CONCLUSION: Computerized vectorcardiography telemetry is a promising new tool for disclosing residual myocardial ischemic activity during the mobilization phase of patients with acute coronary syndromes. The clinical value of CVT needs further investigation in future trials.

Angina, Unstable↗
PubMed1993

Electrocardiographic assessment of infarct size: comparison between QRS scoring of 12-lead electrocardiography and dynamic vectorcardiography.

Myocardial infarct size is one of the most important predictors of prognosis in patients suffering an acute myocardial infarction. It can be assessed by enzymatic and electrocardiographic methods. The present report compares dynamic vectorcardiographic monitoring, serial plasma enzyme activity measurements and QRS scoring according to Palmeri as techniques for infarct size estimation. We report the results from 74 patients with acute myocardial infarction, who participated in a randomized trial of treatment with alteplase. A good correlation was found between myocardial infarct size by estimation from enzymatic measurement and from dynamic vectorcardiography. Dynamic vectorcardiography correlated more closely with enzymatically estimated infarct size in patients with Q-wave infarction, regardless of infarct location, than did QRS scoring of the conventional 12-lead electrocardiogram. Furthermore, dynamic vectorcardiography requires no time-consuming analysis and can be used for on-line monitoring of patients with ongoing infarction to estimate the size of an acute infarction while it is developing.

Clinical Enzyme Tests↗
PubMed2000

Assessment of myocardium at risk in pigs with single photon emission computed tomography and computerized vectorcardiography during transient coronary occlusion.

Since myocardium at risk (MAR) is the major prognosticator of final infarct size and outcome in patients with acute myocardial infarction, it is highly desirable to estimate the size of the acutely ischemic myocardium, that is the MAR, in these patients. We assessed MAR size by Tc-99m-sestamibi-SPECT and computerized vectorcardiography using autoradiography as reference method. Transient myocardial ischemia was achieved in 12 pigs by coronary artery occlusion with PTCA catheters. During the procedure, computerized vectorcardiography was continuously recorded. After injection of Tc-99m-sestamibi and gadolinium-153-labelled microspheres, MAR size was estimated by SPECT and post-mortem autoradiography. Different cut-off levels (50-70%) were compared with respect to MAR-SPECT. Tc-99m-sestamibi-SPECT showed a good correlation with autoradiography (r = 0.94). Computerized vectorcardiography showed a good correlation with autoradiography as well as with Tc-99m-sestamibi-SPECT (STC-VM: r = 0.75 and 0.80, respectively, ST-VM: 0.75 and 0.87, respectively). It was found that 1) MAR assessed by Tc-99m-sestamibi-SPECT correlates closely with the autoradiographic reference; 2) a lower cut-off point of 60% of maximum uptake for MAR by Tc-99m-sestamibi-SPECT gives the closest correlation with the autoradiographic reference; and 3) ST-VM and STC-VM correlate well with MAR assessed by Tc-99m-sestamibi-SPECT and autoradiography.

Animals↗
PubMed1988

A hundred years of progress in electrocardiography. 2: The rise and decline of vectorcardiography.

Throughout the 20th century electrocardiography has been almost exclusively preoccupied by the single dipole concept as a model to account for body surface manifestations of cardiac electrical activity. Vectorcardiography, based on the single dipole approximation as an equivalent cardiac generator, has prevailed for over one half of this century as one of the most prominent components of electrocardiographic research. In retrospect, vectorcardiography has had conceptually an important impact on the progress in electrocardiography although it never became widely used in clinical practice. Recent comparative studies have confirmed that the diagnostic information contents of the standard 12-lead electrocardiogram and the vectorcardiogram are practically identical if adequately powerful, identical diagnostic classification procedures are used in extracting diagnostic information. After serving a useful role as a conceptual model, vectorcardiography is gradually fading away, being replaced by more realistic cardiac source models and by body surface leads supplementing in a better way the information content of the standard ECG leads.

Animals↗
PubMed1987

[Clinical utility of spatial color mapping vectorcardiography in diagnosing myocardial infarction: comparison with 201Tl scintigraphy].

The feasibility of spatial color mapping vectorcardiography in diagnosing the site and extent of the old myocardial infarct was evaluated in comparison with 201T1 scintigraphy. Vectorcardiographic data made by Frank's technique were entered in the personal computer and the QRS complexes were plotted over 112 points crossing the latitude of each 20 (from 20N to 80S) degrees and longitude of each 20 degrees from 20W to 20E on the spherical body. Eight colors were assigned according to the direction of the QRS vector. To construct a territorial map, the apical, then, the septal, anterior, lateral, inferior and posterior portions were determined from the normal 201Tl scintigrams. Myocardial images obtained in the anterior, left anterior oblique and lateral projections were analyzed by the circumferential profile curve. Diagnostic specificity for infarction was greater than 60%, and especially high (90%) in the anterior, apical and lateral regions, but relatively low (50%) in the septal, inferior and posterior regions. Accuracies exceeded 64%. The infarcted areas assessed by spatial color vectorcardiography agreed with those assessed by 201T1 myocardial scintigraphy. Thus, spatial color vectorcardiography was simple and useful for diagnosing the site and extent of myocardial infarction.

Adult↗
PubMed1996

Computerized vectorcardiography for improved perioperative cardiac monitoring in vascular surgery.

BACKGROUND: Postoperative cardiac complications occur frequently after noncardiac operations in high-risk patients. Routine cardiac monitoring is usually done by electrocardiographic (ECG) methods. The present analysis shows that computerized vectorcardiography (VCG) is superior to traditional ECG monitoring in predicting postoperative cardiac complications. STUDY DESIGN: Thirty-eight patients scheduled for abdominal aortic operations were monitored intraoperatively and for 48 hours postoperatively using VCG. These data were analyzed in a blinded fashion, and compared to cardiac outcome and regularly calculated 12-lead ECGs. RESULTS: Thirteen patients suffered from cardiac events: myocardial infarction (n = 3), cardiac death (n = 1), recurrent myocardial ischemia (n = 1), arrhythmias (n = 2), congestive heart failure (n = 2), and arrhythmias combined with congestive heart failure (n = 4). Thirty of 38 patients had ischemia recorded on their VCG, including all 13 patients with cardiac events. Only seven of the 13 patients had ischemic changes on the V5-lead alone and ten on the three leads II, V4, V5, yielding a sensitivity of 54 percent (V5), 77 percent (II, V4, V5) and 100 percent (VCG). Signs of ischemia appeared 400 +/- 690 (mean plus or minus standard deviation) minutes earlier (median 78 minutes, with a range of zero to 2,284 minutes), and never later on the VCG compared to the three leads II, V4, V5. CONCLUSIONS: Vectorcardiography in this risk group shows increased sensitivity in predicting perioperative cardiac complications and earlier ischemia detection than the most sensitive scalar leads. Vectorcardiography substantially improves the possibility of earlier intervention, potentially reducing the incidence of postoperative cardiac complications.

Aged↗
PubMed1999

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.

Aged↗
PubMed1995

Minimal influence of anaesthesia and abdominal surgery on computerized vectorcardiography recordings.

Myocardial infarction still represents a major cause of morbidity and mortality following surgical procedures. Continuous computerized on-line vector-ECG has previously been shown to be useful in the detection of myocardial ischaemia, in acute myocardial infarction and unstable angina pectoris and for ischaemia monitoring after PTCA procedures. This method was presently tested for the possible influence of anaesthesia and surgery during cholecystectomy under general anaesthesia (n = 9), and during inguinal hernia repairs using a spinal block (n = 5). The patients had no history, symptoms or signs of ischaemic heart disease. Analyses of vectorcardiographic changes were made in relation to predefined standardized anaesthetic and surgical procedures, all of which potentially could influence the vector-ECG. Three vectorcardiographic trendparameters were studied: QRS-vector difference, ST-vector magnitude and ST-change vector magnitude. The overall vectorcardiographic changes were minimal and smaller than vectorcardiographic changes previously reported during myocardial ischaemia and infarction. Since anaesthetic and surgical procedures per se had only minor effects on the vector ECG recordings, it is concluded that continuous computerized on-line vectorcardiography will not be skewed by these procedures. Hence, vectorcardiography has the potential of becoming a new monitor for the detection of perioperative myocardial ischaemia.

Adult↗
PubMed1975

[Vectorcardiography].

The principle of vectorcardiography is first discussed. The setting out in space is very instructive. An over-valuation of slight vectorcardiographic changes can lead to wrong conclusions. The changes in right hypertrophy may in many cases be important for diagnosis. This is true for cases of intraventricular conduction disturbance and incomplete right bundle branch block. In certain cases of myocardial infarction, the vectorcardiogram can be valuable as additional diagnostic method. Finally the diagnostic possibilities of vectorcardiography in pacemaker patients, contour irregularities of the vector loops, congenital valvular heart disease and ventricular extrasystole, and the question of standardisation are discussed.

Bundle-Branch Block↗