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PubMed1986

When is the vectorcardiogram superior to the scalar electrocardiogram?

The clinical usefulness of the vectorcardiogram is well documented by the numerous reports published in the last 3 decades. It has been found more reliable than the electrocardiogram for the diagnosis of atrial enlargement and right ventricular hypertrophy. It is more sensitive than the electrocardiogram in the recognition of myocardial infarction, especially if the infarction is inferior or if it occurs in the presence of left bundle branch block or left anterior hemiblock. It is helpful in the diagnosis of ventricular pre-excitation and in the localization of the bypass tract. Some repolarization abnormalities are more clearly demonstrated by the vector display. However, some information, such as that on cardiac chamber size and myocardial damage, can also be obtained by other noninvasive tests that are often performed on the same patients. With the increasing awareness of cost-effectiveness of various laboratory procedures in medicine, the vectorcardiogram should no longer be considered a routine cardiac test and should be requested only for a specific clinical purpose. When properly utilized, vectorcardiography should remain a valuable diagnostic as well as teaching tool.

Cardiomegaly↗
PubMed1999

Admission risk assessment by cardiac troponin T in unstable coronary artery disease: additional prognostic information from continuous ST segment monitoring. TRIM study group. Thrombin Inhibition in Myocardial Ischemia.

OBJECTIVES: We investigated whether the addition of 24 h of continuous vectorcardiography ST segment monitoring (cVST) for an early (within 24 h of the latest episode of angina) determination of cardiac troponin T (cTnT) could provide additional prognostic information in patients with unstable coronary artery disease (UCAD), i.e., unstable angina and non-Q wave myocardial infarction. BACKGROUND: Determination of cTnT at admission and cVST are individually reported to be valuable techniques for the risk assessment of patients with UCAD. METHODS: Two hundred and thirty-two patients suspected of UCAD were studied. Patients were followed for 30 days, and the occurrence of cardiac death or acute myocardial infarction (AMI) were registered. RESULTS: One ST segment episode or more (relative risk [RR] 7.43, p = 0.012), a cTnT level > or = 0.20 microg/liter (RR 3.85, p = 0.036) or prestudy medication with calcium antagonists (RR 3.31, p = 0.041) were found to carry independent prognostic information after multivariate analysis of potential risk variables. By combining a cTnT determination and subsequent cVST for 24 h, subgroups of patients at high (25.8%) (n = 31), intermediate (3.1%) (n = 65) and low risk (1.7%) (n = 117) of death or AMI could be identified. CONCLUSIONS: Twenty-four hours of cVST provides additional prognostic information to that of an early cTnT determination in patients suspected of having UCAD. The combination of biochemical and electrocardiographic methods provides powerful and accurate risk stratification in UCAD.

Adult↗
PubMed1998

Vectorcardiographic changes as predictors of cardiac complications during major vascular surgery.

OBJECTIVE: To elucidate the relation of changes in computerized vectorcardiographic trend parameters indicating perioperative myocardial ischemia with perioperative cardiac complications. DESIGN: Prospective clinical study. SETTING: A single university hospital. PARTICIPANTS: Thirty-eight patients undergoing elective abdominal aortic surgery. INTERVENTIONS: Computerized vectorcardiography recorded during surgery and for 48 hours postoperatively. MEASUREMENTS AND MAIN RESULTS: Vectorcardiographic spatial alterations in the QRS complex (QRS-VD) and absolute (ST-VM) and spatial (STC-VM) ST-segment changes, previously used indicators of myocardial ischemia, were analyzed and related to the cardiac events detected clinically. In five patients with clearly ischemic (cardiac death, myocardial infarction, recurrent ischemia) and eight patients with possibly ischemic (congestive heart failure, arrhythmia) perioperative cardiac events, ST-VM and STC-VM were significantly increased intraoperatively. Postoperatively, these differences remained, but QRS-VD were also significantly increased. Intraoperative and postoperative changes indicating ischemia were strongly related (r = 0.83). The signs of ischemia were most pronounced during the postoperative 12 to 36 hours. The presence of 60 minutes of signs of ischemia during 2 hours revealed high sensitivity (85%), specificity (80%), and positive (69%) and negative (91%) predictive values for subsequent cardiac events. Traditional vector loop analysis showed signs of non-Q-wave infarctions in six patients, whereas only three of these were detected using standard clinical methods. CONCLUSIONS: Vectorcardiographic signs of myocardial ischemia were significantly increased intraoperatively, but most pronounced postoperatively in the patients subsequently suffering cardiac events. The changes could be related to the individual cardiac morbidity with acceptable precision. Thus, continuous vectorcardiographic monitoring may be beneficial for patients at risk of developing perioperative ischemia.

Aged↗
PubMed2001

Deterioration in peak systolic velocity is closely related to ischaemia during angioplasty: a vectorcardiographic and tissue Doppler imaging study.

We tested the hypothesis that the extent of signs of ischaemia detected by vectorcardiography (VCG) during elective coronary angioplasty (percutaneous transluminal coronary angioplasty; PTCA) is related to systolic and diastolic myocardial velocities, as determined by tissue Doppler echocardiography. A total of 15 patients undergoing PTCA (12 men/three women; age 61+/-9 years), without prior myocardial infarction and with an ejection fraction of >50%, were included. The balloon inflation was repeated three times, with minimum intervals of 2 min between inflations. Tissue Doppler echocardiography was performed, in an apical two- or four-chamber view, before and at the end of each inflation. Peak systolic velocity, time-to-peak systolic velocity (TTP), peak early (E(m)) and late (A(m)) diastolic velocities, the E(m)/A(m) ratio and isovolumic relaxation time were measured in the basal segments of the left ventricle. VCG recordings were carried out during the whole procedure. ST vector magnitude (ST-VM) and ST change vector magnitude (STC-VM) were monitored. The total duration and area of each VCG change during inflation were calculated for each patient. Isovolumic relaxation time, peak E(m) and A(m) values and the E(m)/A(m) ratio did not change significantly during inflation. Peak systolic velocity decreased (6.7+/-2.0 to 5.3+/-1.9 cm/s; P<0.001) and TTP increased (157+/-60 to 192+/-60 ms; P<0.01) during inflation. Both STC-VM time (r=-0.68, P<0.01) and STC-VM area (r=-0.68, P<0.01) were related to peak systolic velocity during inflation. STC-VM time was also related (r=0.55, P<0.05) to the difference in peak systolic velocity during compared with before inflation. ST-VM was less closely related to peak systolic velocity. Thus the duration and degree of ischaemia, as measured by VCG, are related to peak systolic velocity in the basal segments of the left ventricle.

Aged↗
PubMed1999

Streptokinase antibodies inhibit reperfusion during thrombolytic therapy with streptokinase in acute myocardial infarction.

OBJECTIVES: To evaluate the influence of pretreatment IgG against streptokinase on the outcome of streptokinase treatment in acute myocardial infarction. SETTING: Coronary care unit. DESIGN: From 88 patients admitted to the coronary care unit due to chest pain, blood samples were taken for determination of the pre-existing titre of antibodies against streptokinase. The patients were treated and monitored according to standard protocols. Fifty of the patients received thrombolytic therapy with streptokinase due to acute myocardial infarction and were monitored with continuous dynamic vectorcardiography, making possible the continuous analysis of ST- and QRS-vector changes and determination of the event of reperfusion. None of these 50 patients had been given streptokinase therapy previously. RESULTS: According to the vectorcardiographic criteria 21(42%) patients had signs of early (within 2 h) reperfusion after streptokinase therapy. These patients had lower pre-existing antibody titres than patients without signs of reperfusion (mean values 0.20 and 0.45 arbitrary units, P = 0.01). None of the patients with a titre higher than 0.50 arbitrary units (nine patients) had signs of early reperfusion. Of the 41 patients with a titre lower than 0.50 arbitrary units 52.5% had signs of early reperfusion. CONCLUSION: The present investigation indicates that pre-existing streptokinase antibodies play an important role in reperfusion failure during thrombolytic therapy with streptokinase in acute myocardial infarction. Therefore, the determination of streptokinase antibodies may differentiate between those patients who may benefit from streptokinase treatment and those who should be treated with some other regime.

Enzyme-Linked Immunosorbent Assay↗
PubMed2002

The effect of streptokinase neutralizing antibodies on fibrinolytic activity and reperfusion following streptokinase treatment in acute myocardial infarction.

OBJECTIVES: To evaluate tissue plasminogen activator (tPA) activity as a measure of fibrinolytic response to treatment with streptokinase (SK) and to relate this to the effect of pretreatment SK antibodies and to successful reperfusion assessed by continuous computerized vectorcardiography (VCG). SETTING: Umeå University Hospital. SUBJECTS: A total of 104 patients with acute myocardial infarction (AMI) treated with SK and no history of previous SK treatment were studied. The tPA activity was measured 4 h after the start of treatment. The effect of pre-existing neutralizing antibodies to SK was analysed with a functional assay in pretreatment samples. Reperfusion was evaluated with VCG. MAIN OUTCOME MEASURES: Successful reperfusion. RESULTS: Fifty-five patients (53%) were classified as successfully reperfused. The risk for failed reperfusion was calculated in logistic regression models. In a univariate model, a borderline significant increase in the risk of failed reperfusion was observed in intermediate levels of SK neutralizing antibodies, but not in the highest levels. In a multivariate model, only high tPA activity, >25 U mL(-1), at 4 h (OR 0.17: 95% CI: 0.06-0.51) was associated with a higher rate of reperfusion whilst longer time to treatment (OR 1.17; 95% CI: 1.02-1.35) was associated with a higher risk of failed reperfusion. There was no significant correlation between neutralizing antibodies to SK and tPA activity at 4 h. CONCLUSION: The SK treatment of AMI induced high levels of tPA activity which were associated with successful reperfusion. The effect of pre-existing SK antibodies had no significant influence on reperfusion and were not correlated to the fibrinolytic activity obtained.

Aged↗
PubMed1999

Prognostic value of maximum ST-vector magnitude during the first 24 h of vectorcardiographic monitoring in patients with unstable angina pectoris.

AIMS: To assess the prognostic importance of alternate ways of quantifying myocardial ischaemia by continuous ST analysis, the maximum ST vector magnitude and the area under the ST vector magnitude trend curve during the first 24 h of continuous ST monitoring. METHODS AND RESULTS: During a 22-month period from 1991 to 1993, 195 patients admitted to our CCU with suspected unstable angina pectoris, were included in the study. During the first 24 h the patients were monitored for ischaemic episodes with computerized vectorcardiography, using a MIDA 1000 system. Twenty seven (14%) of the 195 patients died or had a non-fatal myocardial infarction within 1 year and the maximum ST vector magnitude among those patients was, on average, 201 microV compared with 118 microV in patients who survived 1 year free of myocardial infarction (P<0.01). The area under the ST vector magnitude trend curve was, on average, 1598 microVmin compared with 164 microVmin (P<0.01). By multivariate analysis, the maximum ST vector magnitude emerged as a superior predictor of death or myocardial infarction, compared with the area under the ST vector magnitude trend curve and the number of ST vector magnitude and ST change vector magnitude episodes. The maximum ST vector magnitude and age were independent predictors of death or non-fatal myocardial infarction within 1 year. CONCLUSION: Maximum ST vector magnitude during the first 24 h of vectorcardiographic monitoring seems to be a strong predictor of subsequent death or non-fatal myocardial infarction.

Aged↗
PubMed2001

Early assessment of long-term risk with continuous ST-segment monitoring among patients with unstable coronary syndromes. Results from 1-year follow-up in the TRIM study.

A total of 323 patients who took part in the TRIM trial underwent an initial 24 h continuous electrocardiogram ST-segment monitoring. A ST vector magnitude (ST-VM) maximum > or = 144 microV predicted death or myocardial infarction within 1 year with a 78% specificity and a 52% sensitivity, an area under the ST-VM trend curve > or = 162 mu with a 86% specificity and a 42% sensitivity and presence of ST-VM episodes with a 70% specificity and a 68% sensitivity. Patients who had neither ST-VM episodes nor a ST-maximum > or = 144 microV had only a 4.5% incidence of death or myocardial infarction within one year as compared to 18% among those patients who met any of these criteria. ST-segment monitoring with continuous vectorcardiography is feasible for risk stratification at least up to 1 year after an episode of unstable coronary artery disease and several vectorcardiographic parameters may be used.

Adult↗
PubMed1984

Reduction of infarct size with the early use of timolol in acute myocardial infarction.

One hundred forty-four patients admitted to the hospital within four hours after onset of symptoms of myocardial infarction were randomly assigned to either intravenous timolol treatment or to placebo. Timolol was given intravenously for the first 24 hours and orally thereafter for the duration of hospitalization. Infarct evolution was assessed by continuous vectorcardiography and creatine kinase release. The timolol group had reduced myocardial ischemia and infarct size as measured by an accelerated reduction of ST-vector magnitude, a significant reduction of maximal cumulative creatine kinase release (29.5 per cent), and significantly smaller changes in QRS-vector variables (20 to 25 per cent). Furthermore, the predicted creatine kinase release and maximal QRS-vector change for a given initial ST-vector magnitude was significantly reduced in the timolol group. Timolol was also associated with significant reductions in pain and need for analgesics and was well tolerated overall. This study supports the use of intravenous timolol in the early phase of suspected myocardial infarction to limit infarct size.

Administration, Oral↗
PubMed2000

Iodixanol and iohexol in cardioangiography. A comparative vectorcardiographic study.

PURPOSE: The non-ionic dimeric contrast medium (CM) iodixanol is isotonic with blood through the addition of electrolytes. In this study, we evaluated computerised dynamic vectorcardiography (VCG) as a tool in CM research by comparing the electrophysiological effects of iodixanol with those of the low-osmolar CM iohexol. MATERIAL AND METHODS: A total of 119 patients referred for cardioangiography were included in this double-blind, randomised, parallel comparison of iodixanol (320 mg I/ml) and iohexol (350 mg I/ml). VCG was recorded and different VCG parameters were analysed. General tolerability, safety and radiographic efficacy were also assessed. RESULTS: Iodixanol induced less changes than iohexol in all VCG parameters and the sensation of warmth was significantly milder after iodixanol, but both CM were well tolerated. VCG might be useful in future studies to analyse electrophysiological effects caused by CM.

Contrast Media↗
PubMed2000

Early diagnosis and exclusion of acute myocardial infarction by two hours' vector-ECG and determination of either myoglobin or CK-mb. BIOMACS-study. BIOchemical Markers in Acute Coronary Syndromes.

This retrospective study assesses the early diagnostic potential of a combination of multilead continuous vectorcardiography (VCG) and biochemical markers (myoglobin, troponin-t and CK-mb mass) in patients with chest pain who present with suspected acute myocardial infarction (AMI), but without ST-elevation on resting 12-lead ECG on admission. Within a multicenter study 56 patients admitted for chest pain (< 12 h) and with a non-diagnostic 12-lead ECG on admission and a VCG recording were included. Venous blood samples were drawn on admission and the continuous VCG was monitored for 2 h. The results were related to the clinical diagnosis of AMI. Neither the biochemical markers nor VCG alone permitted the diagnosis or exclusion of AMI at admission. However, if either analysis of myoglobin on admission or 2 h of VCG recording were positive, they would have a sensitivity for detection of AMI of 100% and specificity of 69%. In a subset of patients with more than 4 h delay since start of chest pain, CK-mb could replace myoglobin and give a sensitivity of 100% and a specificity of 81%. Determination of myoglobin or CK-mb at admission and VCG monitoring for 2 h can reliably confirm or exclude AMI within 2 h. This combination seems useful for early stratifications of patients in chest pain or coronary care units.

Adult↗
PubMed2001

Vectorelectrocardiography in coronary artery disease.

Continuous ST-segment monitoring by either continuous 12-lead ECG or continuous vectorcardiography provides reliable information regarding ST changes in patients with ongoing myocardial ischemia with or without concurrent chest pain. ST-segment monitoring enables the clinician to continuously follow the dynamic changes that characterize unstable angina and acute myocardial infarction syndromes. It provides important information for risk stratification in unstable coronary syndromes and helps in differentiating between extra-cardiac chest pain and acute coronary disease. The use of VECG for detection of perioperative myocardial damage is promising but much work still needs to be done to clarify the prognostic and clinical value of VECG in this setting.

Coronary Disease↗
PubMed1993

Ischaemia and reperfusion induced transient QRS vector changes: relationship to size of the ischaemic territory.

OBJECTIVE: The aim was to investigate QRS vector changes during the first 30 min of coronary occlusion or the early phase of reperfusion with special reference to location and size of myocardium at risk. METHODS: 24 h experiments were performed in closed chest anaesthetised pigs. QRS vectors were studied by computerised vectorcardiography via Frank leads. Occlusion of the left anterior descending coronary artery followed by reperfusion was induced in 23 pigs and a sustained occlusion in 20 pigs: left anterior descending coronary artery in seven, right coronary artery in eight, and left circumflex coronary artery in five. Myocardium at risk was measured in postmortem autoradiograms. Eight animals were excluded. RESULTS: Four minutes after occlusion, QRS(mean) deviated towards the ischaemic region in 34/35 animals and returned thereafter at varying speeds. In half of the reperfused animals, deviation of QRS vectors towards the ischaemic territory was also observed during the first minutes of reperfusion. A paradoxical increase in QRS vector changes, "reperfusion peak", was recorded during the initial minutes of reperfusion in 12/19 animals. Maximum spatial QRS vector magnitude increased in all right coronary or left circumflex coronary occlusion animals compared to 6/25 in left anterior descending coronary occlusion animals. QRS vector difference, change in spatial QRS vector angle, and maximum change in QRS azimuth 4 min after occlusion correlated significantly with extent of myocardium at risk. CONCLUSIONS: Marked directional and quantitative QRS vector changes, with significant relation to size and location of myocardium at risk, were recorded during the initial minutes of ischaemia. The transient increase in QRS vector changes during the first minutes of reperfusion deserves further exploration as a new indicator of reperfusion.

Animals↗
PubMed1992

Exercise-induced QRS changes in healthy men and women: a multivariate analysis on their relation to background data and exercise performance.

Changes in the QRS segment during exercise have repeatedly been suggested to provide diagnostic information with respect to ischaemic heart disease, but the subject is controversial. In order to study the possibly confounding effects of gender, age, resting ECG and exercise performance, 50 healthy subjects were investigated with computerized vectorcardiography during a maximal ergometer exercise test. The overall change in the QRS complex decreased significantly with age and female gender (P < 0.001). However, these responses were better explained by baseline QRS size, change in heart rate and systolic blood pressure (adjusted r2 > 0.70, vs adjusted r2 > 0.41). Effects of age were seen in the Y-lead, and gender effects in the X- and Z-leads (P < 0.0001). In multivariate analyses, X- and Y-lead alterations correlated negatively to change in heart rate and resting QRS size (X-lead; adjusted r2 > 0.50, Y-lead; r2 > 0.44). Z-lead alterations correlated negatively with female gender and resting Z-lead QRS size (adjusted r2 > 0.31). ST changes correlated with QRS changes in the X- and Y-leads (P < 0.05). QRS changes immediately after exercise correlated with alterations during exercise (P < 0.004), maximal load (P < 0.01) and time to hypotension post-exercise (X- and Z-lead; P < 0.02). In conclusion, QRS changes appear to be related to baseline QRS size, change in heart rate and ST change, factors which may have important confounding effects. Consideration of these factors may help in resolving the controversy surrounding QRS changes.

Adult↗
PubMed1992

Continuous ST- and QRS-vector changes and myoglobin release during streptokinase-treated acute myocardial infarction.

Twenty-two consecutive patients with a first myocardial infarction treated with streptokinase (SK) were compared to a group of 33 consecutive patients who did not receive SK. Age, infarct localization, duration of symptoms and infarct size, as estimated by cumulative creatine kinase (CK) release, did not differ between the two groups. Myoglobin (MG) release stopped after 5.5 +/- 3.3 h in SK-treated patients, which was 11 h earlier than in the controls (P less than 0.0001). CK release ceased after 15 +/- 7.8 h, about 13 h earlier than in the controls (P less than 0.0001). ST and QRS vector changes, registered by continuous vectorcardiography, were completed after 2.9 +/- 2.0 and 4.4 +/- 2.5 h respectively, about 2 and 4 earlier than in the controls (P less than 0.005 and P less than 0.0001 respectively). With SK, the termination of ST and QRS vector changes occurred more uniformly than corresponding vector changes in the controls, in whom a longer time interval between the termination of ST and the end of QRS vector changes was observed. With SK, the difference between the end of ST and QRS vectors decreased by about 3 h to 1.6 +/- 1.5 h (P less than 0.0001). Temporal relations between MG release and ST and QRS vector changes were similar but more uniform than in those of the reference group. In conclusion, we found that SK resulted in an accelerated and more uniform development of the infarct process, ending about 10 h after onset of therapy, compared with 20-30 h in the reference group.

Aged↗
PubMed1992

The heart in Duchenne muscular dystrophy: a non-invasive longitudinal study.

Sixteen boys with Duchenne muscular dystrophy (DMD) underwent serial investigations of echocardiographic left ventricular dimensions, systolic time intervals (STI), ECG and vectorcardiography (VCG). Spirometry with measurement of vital capacity and forced expiratory volume was also performed, as well as tests of muscle function. ECG was abnormal with high right precordial R-amplitudes even in the youngest patients. In contrast, VCG QRS area progressively diminished with age. STI and echocardiographic contractility indices decreased with increasing age. There was no clinically useful relationship between the various non-invasive variables on the one hand and results from skeletal muscle tests or lung function tests on the other, or between the different cardiac investigation methods. It is concluded that several non-invasive tests are needed during follow-up studies of Duchenne patients to evaluate the effects of treatment or assess prognosis.

Adolescent↗
PubMed1988

Maximal spatial ST vector of S-T segment elevation in the right praecordial leads on electrocardiogram due to acute pericarditis.

Three patients with acute pericarditis with S-T segment elevation in the right praecordial leads were studied by vectorcardiography. The vectorcardiographic findings suggested that, in acute pericarditis, the maximal spatial ST vector pointed to the left-anterior-inferior direction. The S-T segment elevations in the right praecordial leads in these patients were due to the large magnitude of the maximal spatial ST vector. Its magnitude indirectly caused S-T segment elevation in the right praecordial leads adjacent to it during the acute stage of pericarditis.

Acute Disease↗
PubMed1988

Patterns of maximal spatial ST vector of S-T segment elevation in the right praecordial leads of the electrocardiogram in patients with acute inferior myocardial infarction.

Thirty patients with S-T segment elevation in the right praecordial leads during acute inferior myocardial infarction were studied by vectorcardiography. From the vectorcardiographic traces two types of maximal spatial ST vectors were seen. Their directions pointed either to: (1) the right-anterior-inferior, or (2) the right-posterior-inferior octant. This spatial ST vector could cause S-T segment elevation in the right praecordial leads in patients with acute inferior myocardial infarction in two ways. (1) The projection of the right-anterior-inferior maximal spatial ST vector on the horizontal plan pointing to right-anterior direction directly causes S-T segment elevation in the right praecordial leads--only a minority of patients (20%) show this. (2) The large magnitude of the right-posterior-inferior maximal spatial ST vector indirectly causes S-T segment elevation in the right praecordial leads adjacent to it. The majority of patients (80%) belong to this group. Therefore, the maximal S-T segment elevation in the electrocardiogram should be looked for in leads V5R to V8R. The direction of the vectors imply that in some patients there would be no S-T segment elevation in lead V4R. This study indicates that the use of S-T segment elevation in V4R, or several right praecordial leads, to claim that the maximal ST vector points to the right-anterior direction can be misleading. Without directional information, the use of single lead or several leads to detect the maximal spatial ST vector by a scalar electrocardiogram will give incomplete information.(ABSTRACT TRUNCATED AT 250 WORDS)

Bundle-Branch Block↗