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At least 649 records · Page 36Linked to original sources
PubMed1997

Vectorcardiographic changes during laparoscopic cholecystectomy may mimic signs of myocardial ischaemia.

BACKGROUND: Laparoscopic surgery involves the use of intra-abdominal carbon dioxide insufflation (pneumoperitoneum). The increased intra-abdominal pressure causes marked haemodynamic changes, which may influence electrocardiographic monitoring. The aim of the present study was to elucidate the influence of pneumoperitoneum on vectorcardiographic recordings. METHODS: Vectorcardiographic changes (QRS vector difference = QRS-VD, QRS loop area, QRS magnitude, ST vector magnitude, spatial ST vector change) were recorded continuously applying computerized vectorcardiography in 12 anaesthetised cardiovascularly healthy patients, scheduled for laparoscopic cholecystectomy. Measurements were made before and during pneumoperitoneum in three different body positions (supine, Trendelenburg and reversed Trendelenburg), also employing transesophageal echocardiography and invasive blood pressure monitoring. RESULTS: Pneumoperitoneum significantly increased QRS-VD, in parallel with an enlargement in loop area and magnitude. The magnitude was significantly increased in the transversal and frontal planes and there was a tendency to increase the magnitude in the sagittal plane. The increase in QRS-VD reached levels previously associated with the development of myocardial ischaemia in patients with coronary artery disease. The ST-variables were not changed by the pneumoperitoneum. The positional changes also influenced QRS-VD significantly. CONCLUSIONS: When computerized vectorcardiography is used for ischaemia monitoring during pneumoperitoneum, the ST-variables seem reliable. However, vectorcardiographic QRS-changes should be interpreted with caution, as the QRS alterations found during pneumoperitoneum mimic the changes seen during myocardial ischaemia.

Adult↗
PubMed1980

Vectorcardiographical and pathological approach to the relationship between cardiac hypertrophy and coronary arteriosclerosis in spontaneously hypertensive rats (SHR).

To study the pathophysiology and the pathogenesis of hypertensive cardiac diseases such as cardiac hypertrophy and ischemic heart diseases, and to determine the relationship between these cardiopathies, spontaneously hypertensive rats (SHR) and stroke-prone SHR (SHRSP) were used as models. Vectorcardiography was applied to the rat according to orthogonal Takayasu lead system and "vectorcardiography for small animals" with a good reproducibility was established. Characteristic vectorcardiogram (VCG) was obtained from 5-month-old SHR, compared with normotensive Wistar-Kyoto rats (WK). Left superior (posterior) deviation of QRS vector usually with ST-T changes was recognized as LVH (Left Ventricular Hypertrophy) pattern of SHR and such corresponded to the pathological findings of the increased heart weight and the increased weight and thickness of the left ventricular wall, and also to the high blood pressure. Macroscopical morphological features of the heart were also studied. Chest roentgenography showed and increased cardiothoracic ratio (CTR) and the protrusion of the left ventricular portion in the posteroanterior cardiac silhouette of SHR. The horizontal view of the chest, cross-sectioned by the apparatus of whole body autoradiography, PMV-cryomicrotome 450 MP, indicated the left anterior orientation of the interventricular septum in rats, as is the case in humans, and the clockwise rotation of the left ventricular cavity in SHR, compared with WK. The coronary arterial wall thickening with narrowed lumen was noted even in the prehypertensive 1-month-old SHR. Such correlated well with the wall thickening of the left ventricle. From these vectorcardiographical and morphological studies on SHR and SHRSP, genetic hypertension was ascertained to be significant not only for cardiac hypertrophy but for the coronary arterial wall thickening, both of which may also enhance the myocardial lesions in SHR, particularly in SHRSP.

Animals↗
PubMed1985

Normal vectorcardiographic parameters in infants and children.

Normal ranges of 32 parameters in vectorcardiography were determined in 200 healthy infants and children. The subjects were divided into 5 groups and results were compared in each group. Significant differences were found in 11 parameters. The differences were associated with a physiologically prominent right ventricular load in younger age groups. Therefore, age should be considered in evaluation of vectorcardiography.

Adolescent↗
PubMedDate not supplied

[About vectorcardiographic examination].

The clinical importance of the spatial exploration of the cardiac electrical phenomenon (vectorcardiography), which is a very useful integration of the analytical and limited electrical exploration (electrocardiography), is outlined here. Reasons inducing the mexican school to prefer the Grishman's cube method for the vectorcardiographic recordings of other more elaborate and complex systems, are explained. The former reflects in a more reliable way the sequence of myocardial depolarization and repolarization. Morphological and chronological aspects characteristic of the normal vectorcardiogram in the frontal, horizontal and sagittal planes, are described. Additionally some typical examples corresponding to the three main electrical heart positions are presented. The vertical position is frequent in children and longilineal persons, the intermediate position is common in adults and the horizontal one is observed in age people and brevilineal persons. Some vectorcardiographic aspects typical of myocardial necrosis, injury and ischemia are discussed, underlining the importance of the complementary elements given by vectorcardiography.

Female↗
PubMed1996

Assessment of electrophysiological state of heart in astronauts in terms of decartographic and conventional electrocardiographic characteristics.

Long-term observation of the heart state during specialized professional activities plays an important part in preventive medicine. This study is aimed at assessment of electrophysiological state of heart in astronauts by common electrocardiography, vectorcardiography, and dipole electrocardiotopography (DECARTO technique). The subjects observed were two astronauts performing a long-term flight at the Mir orbital station. DECARTO technique was used to obtain an intelligible-pictorial representation of the data in the form of so-called decartograms for visual and quantitative analysis. The observations showed rather stable chronotopography of the heart depolarization process. However, there was an increase of the maximal magnitude of the electric heart vector and a decrease of the ventricular gradient vector in the middle part of the flight. Just upon landing, a pronounced decrease of the ventricular gradient magnitude, followed by a fast restoration of its value was observed in both subjects. The DECARTO technique used in combination with vectorcardiography facilitated the detailed visual analysis of the electrocardiographic data. (Fig. 3, Ref. 3.)

Astronauts↗
PubMed1999

Decreases by magnesium of QT dispersion and ventricular arrhythmias in patients with acute myocardial infarction.

AIMS: Magnesium treatment suppresses ventricular arrhythmias in acute myocardial infarction and possibly mortality after infarction, but the underlying mechanisms are inadequately understood. We tested whether the effect of magnesium could be attributed to an influence on the autonomic control of the heart, changes in disturbed repolarization, relief of ischaemia or limitation of myocardial injury. METHODS AND RESULTS: Fifty-nine consecutive patients with acute myocardial infarction were randomized to receive 70 mmol of magnesium (n = 31) infused over 24 h or placebo (n = 26). Occurrence of ventricular arrhythmias and heart rate variability (SD of 5-min mean sinus beat intervals over a 24 h period, SDANN; low frequency/high frequency amplitude ratio, LF/HF ratio), and the number of ischaemic episodes on vectorcardiography were measured from the first day of treatment. QT dispersion corrected for heart rate was measured from the 12-lead ECG. Magnesium decreased the number of hourly ventricular premature beats (P < 0.001) and the number of ventricular tachycardias (P < 0.05). QT dispersion corrected for heart rate was decreased in both measurements at 24 h and 1 week (P < 0.001). SDANN and LF/HF ratio were unchanged. The number of ischaemic episodes on vectorcardiography were equal, and peak creatine kinase MB release did not differ between the groups. In testing the pathophysiological mechanisms, serum magnesium levels after infusion correlated with hourly ventricular premature beats (rs = -0.47; P < 0.01), ventricular tachycardias (rs = -0.26; P < 0.05), and QT dispersion corrected for heart rate (rs = -0.75; P < 0.001), but not with SDANN, LF/HF ratio or peak creatine kinase MB. QT dispersion corrected for heart rate correlated with hourly ventricular premature beats (rs = 0.48; P < 0.001) and ventricular tachycardias (rs = 0.27; P < 0.05). CONCLUSIONS: Magnesium suppresses early ventricular arrhythmias in acute myocardial infarction. The decreased arrhythmicity is related to enhancement of homogeneity in repolarization, but not to attenuation of prevailing ischaemia, improvement of autonomic nervous derangements or myocardial salvage.

Adult↗
PubMed1964

THE Q WAVE IN L III AND AVF OF THE ELECTROCARDIOGRAM. A VECTORCARDIOGRAPHIC ANALYSIS WITH THE USE OF THE FRANK SYSTEM.

Seventy-three consecutive patients with a Q wave in Lead III and aVF in the electrocardiogram were studied. Vectorcardiograms were recorded with the use of the Frank system. In 32 cases the ECG's were compatible with the diagnosis of an inferior myocardial infarction based on a Q wave in Lead III and/or aVF greater than 0.04 second duration and greater than 25 per cent of the amplitude of the R wave. In this group, there were 16 patients with coronary disease and the VCG confirmed the electrocardiographic diagnosis of an infarction in 14 cases. In 13 of the other 16 cases without history of coronary disease the VCG did not suggest the presence of an infarction. In all 17 cases with questionable electrocardiographic diagnosis of an inferior infarction, and without history of coronary disease, the VCG denied the presence of an infarction. In 18 cases with small Q III or Q aVF the VCG's were within normal limits. In two cases with normal Q III and Q aVF the VCG's did not detect the presence of an infarction in both cases. The vectorcardiographic diagnosis of an inferior myocardial infarction was based on the superior orientation (at or above 360 degrees) of the 10, 20, 25 and 30-msec vectors in the frontal plane, superior displacement of the maximum QRS vector and clockwise rotation. In the left sagittal plane the 10, 20, 25 and 30-msec vectors were oriented at or above 180 degrees with the loop rotating counterclockwise. The data presented suggest that vectorcardiography is a useful adjunct to electrocardiography in the diagnosis of an inferior myocardial infarction.

Anterior Wall Myocardial Infarction↗
PubMed1983

Cardiogoniometry.

Cardiogoniometry is a new method to test heart function. It consists of a simple computerized vectorcardiography with a system of leads derived for the construction of three orthogonal projections. With the aid of these three-dimensional projections the cardiogoniometer, a microprocessor system, measures and computes the maximal vectors of depolarization (QRS) and repolarization (T). It also fixes the orientation of these two spatial vectors by projection on two planes (frontal and oblique sagittal) and determines the solid angle phi between them. Every third heart beat these five parameters and the preceding beat interval are printed out. In this way, a series of measurements is obtained in which only little disturbances of the signals of cardiac de- and repolarization occur. In patients with latent coronary insufficiency an abnormal position of the T vector can be detected long before the standard ECG shows a pathological pattern. Cardiogoniometry can be performed in the consulting room or at the bedside. It is noninvasive, painless, and free of risk. The value and limits of this new method are to be tested in comparison with the ECG and invasive methods in cardiology laboratories.

Adolescent↗
PubMed1991

Changes in the T-wave vector loop of the three-dimensional vectorcardiogram during exposure to cold pressor stress.

Three-dimensional vectorcardiography was used to characterize changes in the T-wave vector loop during exposure to cold pressor stress. Data were collected from 8 subjects during baseline, cold pressor, and recovery periods. Maximum vector length, polar angle of the longest vector, azimuth angle of the longest vector, sum of all vectors, polar angle of the vector sum, azimuth angle of the vector sum, surface area of the loop, and maximum distance between adjacent vectors were computed from the T-wave vector loop. The amplitude of the one-dimensional T-wave (TWA) was also computed. Interbeat interval and TWA decreased during hand immersion and increased during recovery. Of the vectorcardiographic measures, only maximum vector length and vector sum showed statistically significant change; both decreased during the task and returned to baseline during recovery. TWA accounted for 46% of the task related variance compared to 53% and 47% respectively, for vector sum and maximum vector length. Changes in TWA probably reflect a true change in cardiac electrical potential rather than a change in T-wave vector loop shape or orientation.

Adult↗
PubMed1997

Comparison of electrocardiograms recorded with standard leads and derived from the vectorcardiographic frank leads in high risk patients.

Dynamic vectorcardiography (VCG) is increasingly employed for ischaemia monitoring with the use of a computerized method for recording and on-line analysis by the calculation of trend parameters. To elucidate how well the derived electrocardiogram (dECG), calculated from the VCG, compares with the simultaneously registered standard ECG (sECG), dECGs from 17 postoperative cardiac-risk patients and 36 subjects with acute myocardial infarction (AMI) were compared to sECGs, both quantitatively in leads II, III, V2 and V5 and qualitatively. Despite small, but some significant differences, mainly in the amplitudes of precordial leads, the qualitative interpretation by two independent cardiologists showed good agreement between the methods (kappa = 0.72 and 0.67, respectively) for the diagnosis of AMI/ischaemia. The dECG seems to be reliable and can be used clinically in these groups of patients during VCG recordings.

Aged↗
PubMed2005

Basic techniques of cardiac MR.

Cardiovascular magnetic resonance (CMR) can be performed routinely due to the continued developments of MR systems, coil technology and sequence techniques, which have considerably shortened acquisition times. Techniques for the physiological monitoring of the patients are available for example, to synchronize the data acquisition with the individual heart cycle. The development of vectorcardiography-based (VCG) triggering improves the detection of the R-waves and reduces the number of misinterpreted ECG events to a minimum. Depending on the clinical question, spin or gradient echo-based sequences with different k-space filling methods are used in CMR. For spin preparation, inversion or saturation recovery techniques are used to suppress the signal of a specific tissue, or to maximize the T1 contrast between different soft tissues. Parallel acquisition methods (PAT) are available to speed up CMR imaging even further.

Contrast Media↗
PubMed1976

Intraatrial conduction disturbances: vectorcardiographic patterns.

Frank P loop vectorcardiograms were recorded in 30 normal subjects and in 40 patients who had intraatrial conduction disturbances alone or in association with cardiac disease. High magnification of the P loop (0.1 mv = 3 cm) permitted accurate measurement of the P loop duration, magnitude and direction. High-frequency recordings allowed optimal evaluation of the notches, bites and conduction delays in the PsE loop. Four vectorcardiographic patterns have been selected as counterparts of the four types of enlarged P waves seen in electrocardiograms of patients with atrial conduction disturbances. When intraatrial conduction disturbances coexisted with left atrial enlargment, the PsE loop was larger and smoother. The role of partial or complete block in the specific internodal or interatrial pathways is discussed. High magnification, high-frequency vectorcardiography of the P loop seems to be the best available method for determing a specific pattern of intraatrial conduction disturbance.

Adult↗
PubMed1985

Results of balloon valvuloplasty in the treatment of congenital valvar pulmonary stenosis in children.

Transluminal balloon valvuloplasty was used in the treatment of congenital valvar pulmonary stenosis in 19 children, aged 5 months to 18 years. The right ventricular (RV) systolic pressure and RV outflow tract gradient decreased significantly immediately after the procedure (95 +/- 29 vs 59 +/- 14 mm Hg, p less than 0.01, and 78 +/- 27 vs 38 +/- 13 mm Hg, p less than 0.01). Seven of these patients were evaluated at cardiac catheterization 1 year after balloon valvuloplasty. No significant change occurred in RV systolic pressure or RV outflow tract gradient at follow-up evaluation compared with measurements immediately after balloon valvuloplasty (60 +/- 5 mm Hg vs 56 +/- 12 mm Hg and 39 +/- 5 vs 38 +/- 10 mm Hg). In addition, follow-up evaluation was performed using noninvasive methods and included electrocardiography (n = 13), vectorcardiography (n = 11) and Doppler echocardiography (n = 11) Doppler echocardiography in 11 patients 15 +/- 9 months after balloon valvuloplasty showed a continued beneficial effect with a mild further decrease in RV outflow tract gradient. Thus, balloon valvuloplasty is effective in the relief of pulmonary stenosis.

Adolescent↗
PubMed1986

Validation of a computerized QRS criterion for estimating myocardial infarction size and correlation with quantitative morphologic measurements.

This replication study describes the relation of myocardial infarction (MI) size, measured at autopsy, to initial and late QRS abnormalities, measured by computerized spatial vectorcardiography. Thirty-one patients with MIs of differing ages and left ventricular locations and 24 patients with no evidence of heart disease were studied. The percent volume of MI was significantly estimated by the initial QRS abnormalities (r = 0.94, p less than 0.00001). The 2 regression equations from the previous training set and from this present test set were compared to verify validity of the criterion, the integral of magnitudes of spatial vectors during initial abnormal depolarization to estimate MI size. There was not a significant difference between the 2 intercepts, the 2 slopes, the 2 straight-line regressions or the 2 correlation coefficients. The additional information obtained from late QRS abnormalities contributed little to improve estimation of size of multiple MIs of differing ages and left ventricular locations, but accurately predicted (r = 0.87) the size in single inferobasal MI. The results indicate that vectorcardiographic measurements of early activation abnormalities is a valid criterion to estimate MI size.

Aged↗
PubMed1991

Dynamic QRS-complex and ST-segment monitoring in acute myocardial infarction during recombinant tissue-type plasminogen activator therapy. The TEAHAT Study Group.

Changes of the QRS complex are the electrocardiographic expression of irreversible injury of the myocardium. In humans, the process of infarction occurs over several hours. A more rapid development of QRS changes has been reported in patients treated with thrombolytic agents. Patients with strongly suspected acute myocardial infarction (AMI) included in a placebo-controlled trial of 100 mg of recombinant tissue-type plasminogen activator (rt-PA) were monitored for 24 hours with continuous, on-line vectorcardiography. The magnitude of the QRS vector changes correlated with infarct size estimated by the maximal value of lactate dehydrogenase-1 (r = 0.69, p less than 0.001) as well as with left ventricular ejection fraction 30 days after randomization (r = 0.49, p less than 0.001). Treatment with intravenous rt-PA limited total QRS vector change but the QRS vector changes observed occurred more rapidly and reached a plateau 131 minutes earlier in patients treated with rt-PA than in those receiving placebo (p less than 0.01). A certain pattern of highly variable ST vector magnitude was identified and was associated with higher maximal lactate dehydrogenase-1 values (23 +/- 13 vs 14 +/- 10 mu kat/liter, p less than 0.001) and a tendency to higher 1-year mortality (24 vs 9%, p = 0.08) than in patients without this pattern. In patients with this pattern, rt-PA did not affect maximal lactate dehydrogenase-1, time to maximal creatine kinase and final magnitude of QRS vector change.

Double-Blind Method↗
PubMed1977

A computer system automatic analysis of vectorcardiograms.

This computer system performs the analysis of orthogonal electrocardiograms for vectorcardiographic (VCG) display and classification. The data acquisition can be performed 'on-line' with the complete analysis in 'real-time', or off-line by processing a magnetic tape. The original computational methods for beat averaging and wave recognition are described. Some features, such as the quality of the visual display of the VCG traces, the availability of a measurement matrix allowing the quantitative analysis of the VCG and the use of a data bank for storage, retrieval and statistical studies make this system very efficient for clinical purposes, introducing the concept of 'Computer Assisted Vectorcardiography'.

Diagnosis, Computer-Assisted↗
PubMed1989

Spatial vectorcardiogram in acute inferior wall myocardial infarction: its utility in identification of patients prone to complete heart block.

Spatial vectorcardiography was performed in 28 (22 males, 6 females; age 36-78 years) consecutive cases of acute inferior wall myocardial infarction during sinus rhythm within 24 hours of admission. Orthogonal leads using the corrected Frank lead system were recorded at a paper speed of 100 mm/sec. Qualitative analysis consisted of study of QRS loop inscription in all 3 orthogonal planes. Additional quantitative analysis using the spherical coordinate system was undertaken to measure the magnitude and angular direction (azimuth and elevation angle) of spatial R maximum cardiac vector. During the hospital course, 15 patients developed transient complete heart block and 13 patients did not. The direction of the QRS loop inscription in the 3 planes did not differ between the two groups. The spatial R maximum magnitude and azimuth angle did not differ between the patients who developed complete heart block and those who did not. Values for elevation angle were markedly different between the two groups. The spatial R maximum elevation angle ranged from 0 to -35 degrees and was negative (superiorly directed) in 14 of the 15 patients with complete heart block, whereas it ranged from -10 degrees to +/- 75 degrees and was negative (superiorly directed) in only 2 of the 13 patients without this complication. Thus it appears that negative elevation angle of spatial R maximum cardiac vector in patients with inferior wall myocardial infarction may indicate proneness to complete heart block.

Adult↗
PubMed1993

Impact of early thrombolysis on chest pain score reflecting myocardial ischemia in relation to various markers of ischemic damage. TEAHAT Study Group.

We randomized 352 patients with pain suggestive of acute myocardial infarction who were seen less than 3 h after onset of symptoms to either tissue plasminogen activator or placebo. The impact of treatment on chest pain score was assessed during the first 24 h and related to limitation of final myocardial damage as assessed by various indirect markers. The most marked effect of tissue plasminogen activator was observed in the chest pain score being reduced by 43% in the tissue plasminogen activator group as compared with placebo. Limitation of infarct size with tissue plasminogen activator reached the following percentage values when various methods were used: maximum serum lactate dehydrogenase I activity, 32%; vectorcardiography (QRS vector difference), 20%; electrocardiography (Palmeri score), 20%; ejection fraction, 9%. We conclude that early thrombolysis in acute myocardial infarction reduces the severity of chest pain by nearly 50%. The effect on chest pain is much more marked as compared with the effect on various markers of the final ischemic damage.

Aged↗