Body surface distribution of QRS deflection areas in experimental ventricular preexcitation

Electrocardiographic body surface mapping: potential tool for the detection of transient myocardial ischemia in the 21st century?

Coronary artery disease (CAD) is one of the leading causes of cardiovascular mortality and morbidity worldwide. CAD presents as a wide spectrum of clinical disease from stable angina to ST segment elevation myocardial infarction. The 12-lead electrocardiogram (ECG) has been the main tool for the diagnosis of these events for almost a century but is limited in its diagnostic ability. For patients with suspected angina, the exercise tolerance test is often used to provoke and detect stress-induced ischemia but does not provide a definitive answer in a substantial proportion of patients. Body surface mapping (BSM) is a technique that samples multiple points around the thorax to provide a more comprehensive electrocardiographic data set than the conventional 12-lead ECG. Moreover, recent preliminary data demonstrate that BSM can detect and display transient regional myocardial ischemia in an intuitive fashion, employing subtraction color mapping, making it potentially valuable for diagnosing CAD causing transient regional ischemia. Research is ongoing to determine the full extent of its utility.

Cardiac memory in patients with intermittent Wolff-Parkinson-White syndrome

This study used body surface mapping to evaluate the ventricular repolarization process in the absence of delta waves in 13 patients with the intermittent Wolff-Parkinson-White (WPW) syndrome. The findings were compared with data from 30 normal individuals and 50 patients with the overt WPW syndrome. The QRST isointegral maps of patients with the overt WPW syndrome exhibited abnormal areas and the QRST departure maps showed a peculiar distribution to each accessory pathway site. The QRST isointegral map exhibited abnormal areas in 11 of the 13 cases (85%) of the intermittent WPW syndrome in the absence of delta waves. In 8 of these 11 cases (73%), the distribution of the departure map resembled that in the overt WPW syndrome. These findings suggest that abnormal ventricular repolarization due to cardiac memory is present in patients with the intermittent WPW syndrome even in the absence of delta waves.

Estimation of anterior infarct size with body surface QRST integral maps in the presence of abnormal ventricular activation sequence in dogs

The possibility of estimating infarct size with body surface QRST integral (IQRST) maps was investigated in dogs. IQRST maps were constructed from 87-lead body surface ECGs, which were recorded 1 week after the production of anterior myocardial infarction during artificial pacing that simulated normal conduction, left bundle branch block, and Wolff-Parkinson-White syndrome in 11 dogs. Small differences were observed between the IQRST maps of the normal conduction and left bundle branch block models (r = 0.93, root mean square difference = 8.71 mVmsec) and between the normal conduction and Wolff-Parkinson-White models (r = 0.96, root mean square difference = 6.03 mVmsec). Summation of the QRST integral values over the body surface leads (QRST index) inversely correlated with infarct size in all three conductions models: r = 0.91 (p < 0.001) in the normal conduction model; r = -0.81 (p < 0.001) in the left bundle branch block model; and r = -0.86 (p < 0.001) in the Wolff-Parkinson-White model. These results show that IQRST maps permit noninvasive estimation of infarct size, even in the presence of abnormal activation sequences.

Body surface isopotential mapping of the entire QRST complex in the Wolff-Parkinson-White syndrome. Correlation with the location of the accessory pathway

Body surface potential maps were recorded during sinus rhythm and during atrial pacing at the time of electrophysiologic studies in 42 patients with Wolff-Parkinson-White syndrome. The locations of the accessory pathways were determined by epicardial mapping during surgery in 34 patients and by multicatheter endocavitary electrophysiologic studies in eight additional patients. During delta wave inscription, the shape and extension of areas of the negative and positive potentials on the thorax correlated better with the preexcitation site (69% of patients) than with the localization of the minimum potential alone (45.2% of patients). Typical potential distributions were present from the beginning of the delta wave and remained stationary during the first half of the QRS complex. During marked preexcitation, the superposition of atrial activity on the delta wave produced a mixed pattern in the earliest maps. However, these alterations of early delta thoracic potential distribution did not persist longer than 30 msec. The spread of the negative potentials during the last half of the QRS complex also characterized each localization: right-sided preexcitation reproduced the depolarization sequence of left bundle branch block, left-sided preexcitation reproduced that of right bundle branch block, and posterior pathways resembled left anterior fascicular block. Anterior left ventricular and more anterior left lateral ventricular preexcitations mimicked a right bundle branch block-left posterior fascicular block pattern. There was good correlation between the body surface potential map obtained during the ST segment and the site of the right-sided preexcitation. However, in left-sided preexcitations, ST patterns concordant with delta wave patterns were found less frequently than in right-sided preexcitations.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiographic body surface potential mapping in the Wolff-Parkinson-White syndrome. Noninvasive determination of the ventricular insertion sites of accessory atrioventricular connections

BACKGROUND

A reliable, noninvasive procedure to determine the location of accessory atrioventricular connections in patients with Wolff-Parkinson-White syndrome would add an important diagnostic tool to the clinical armamentarium.

METHODS AND RESULTS

Body surface potential mapping (BSPM) using 180 electrodes in various-sized vests and displayed as a calibrated color map was used to determine the ventricular insertion site of the accessory atrioventricular (AV) connections in 34 patients with Wolff-Parkinson-White syndrome. Attempts were made to determine the 17 ventricular insertion sites described by Guiraudon et al. All 34 patients had an electrophysiologic study (EPS) at cardiac catheterization, and 18 had surgery so the ventricular insertion sites could be accurately located using EPS at surgery. A number of physiologic observations were also made with BSPM.

CONCLUSIONS

The following conclusions were drawn: 1) BSPM using QRS analysis accurately predicts the ventricular insertion site of accessory AV connections in the presence of a delta wave in the electrocardiogram; 2) the ventricular insertion sites of accessory AV connections determined by BSPM and by EPS at surgery were identical or within one mapping site (1.5 cm or less) in all but four of 18 cases; three of the four exceptions had more than one accessory AV connection, and the other had a very broad ventricular insertion; 3) BSPM and EPS locations of the accessory AV connections correlated very well in the 34 cases despite the fact that BSPM determines the ventricular insertion site and EPS determines the atrial insertion site of the accessory AV connection; 4) as suggested by the three cases of multiple accessory AV connections, EPS and BSPM may be complementary since BSPM identified one pathway and EPS identified the other (in the case with a broad ventricular insertion, BSPM and EPS demonstrated different proportions of that insertion); 5) BSPM using ST-T analysis is very much less accurate in predicting the ventricular insertion site of accessory AV connections unless there is marked preexcitation; 6) standard electrocardiography using the Gallagher grid methodology (but with no attempt at stimulating maximal preexcitation) was not as accurate as QRS analysis of BSPM in predicting the ventricular insertion site of the accessory AV connection; however, exact comparison is hampered by the different number and size of the Gallagher and Guiraudon insertion sites; 7) BSPM using QRS analysis appears to be very accurate in predicting right ventricular versus left ventricular posteroseptal accessory AV connections; 8) typical epicardial right ventricular breakthrough, indicative of conduction via the specialized AV conduction system, occurs in all patients with left ventricular free wall accessory AV connections; 9) epicardial right ventricular breakthrough was not observed in cases with right ventricular free wall or anteroseptal accessory AV connections; 10) epicardial right ventricular breakthrough can occur in the presence of posteroseptal accessory AV connections, whether right or left ventricular; and 11) the delay in epicardial right ventricular breakthrough in cases with left ventricular insertion may provide a marker to estimate the degree of ventricular preexcitation.

The role of initial minimum potentials on body surface maps in predicting the site of accessory pathways in patients with Wolff-Parkinson-White syndrome

Forty-one patients (23 men and 18 women, ages 20 to 66 years) with Wolff-Parkinson-White syndrome were studied with isopotential body surface maps during sinus rhythm to find the most reliable index for predicting the sites of single accessory pathways. The sites predicted by surface maps were compared with those confirmed by multicatheter electrophysiologic study or in the course of surgical operation. Location of the initial minimum by a time criterion, 40 msec after onset of the QRS complex, was not reliable enough for prediction in patients with the small delta wave on their electrocardiograms, because ventricular activation via the normal conduction pathway significantly influenced the location of the minimum. Location of the minimum by an amplitude criterion, -0.15 mV or slightly deeper, was influenced minimally by fusion of ventricular activation, the patient's body size, or age and corresponded well to the site of the accessory pathway in 36 of 41 patients. Those minima appeared on circumscribed areas of the map in accordance with the anatomic subdivisions of the atrioventricular ring. Thus location of the minimum by the amplitude criterion was an excellent index for predicting the site of the accessory pathway, regardless of the degree of ventricular fusion. These amplitude-based map features suggest that nonstandard electrocardiograms recorded from selected positions on the body surface can be used as accurate predictors of the sites of accessory pathways.

A quantitative method for the localization of the ventricular pre-excitation area in the Wolff-Parkinson-White syndrome using singular value decomposition of body surface potentials

In order to localize quantitatively the site of ventricular pre-excitation, singular value decomposition (SVD) was applied to the body surface potential distributions of patients with the Wolff-Parkinson-White syndrome. The body surface potentials of sixty-two patients were recorded during sinus rhythm and pre-excitation by means of thirty electrodes placed on the anterior thoracic wall. The sites of the anomalous bundles had been determined beforehand by multicatheter electrophysiologic study. Considerable data reduction was obtained by using the SVD technique and displaying the potential distribution during the delta wave on two isofunction maps of the first two positional vectors and their corresponding two singular values (SV). A distinction was made between two types of isofunction maps. A type-S (single extreme) and a type-D (double extremes). A quantitative analysis was performed with the orientation of the zero line on the isofunction map being represented by the angle alpha or beta, and the singular values quotient (SVQ) of the two first singular values. The angle beta belonging to type D was used to subdivide this group of pre-excitation areas. The parameters SVQ and alpha belonging to type-S were illustrated in a graph on which a distinction between the various locations of the pre-excitation areas can be seen.