Journal of electrocardiology
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Comparative Study Clinical Trial
Comparison of a new reduced lead set ECG with the standard ECG for diagnosing cardiac arrhythmias and myocardial ischemia.
In a few patients, 12-lead electrocardiograms (ECGs) derived from reduced-lead-set configurations do not match the standard ECG. Constructing an ECG from a reduced number of standard leads should minimize this problem because some of the resultant 12 leads would always include "true" standard leads. The purpose of this study was to compare the ability of a new reduced-lead-set 12-lead ECG ("interpolated" ECG) with the standard ECG to diagnose cardiac arrhythmias and acute myocardial ischemia. ⋯ The interpolated 12-lead ECG is comparable to the standard ECG for diagnosing multiple cardiac abnormalities, including wide-QRS-complex tachycardias and acute myocardial ischemia. The advantages of this ECG method are that the standard electrode sites are familiar to clinicians and that eight of the 12 leads are "true" standard leads. Hence, QRS-axis and morphology criteria for diagnosing wide-QRS-complex tachycardia and bundle branch and fascicular blocks are preserved.
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We studied the seasonal variability of QT dispersion in 25 healthy subjects, aged 36 +/- 5 (25 to 46) years. Four seasonal 12-lead rest electrocardiograms (ECGs) recorded at a double amplitude were performed at 25 mm/s at intervals of roughly 3 months. ⋯ There was a seasonal variability in the QT dispersion (P =.001), with the largest QT dispersion occurring in winter (66 +/- 21 ms) and the smallest one in spring (48 +/- 18 ms). In conclusion, there exists a seasonal variability of QT dispersion in healthy subjects and such variability should be taken into consideration in comparison of the QT dispersion.
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Case Reports
Diagnosis of myocardial infarction-induced ventricular aneurysm in the presence of complete left bundle branch block.
An analysis of the 4,196 files of our Cardiology Clinic cohort showed 128 patients with a complete left bundle branch block (LBBB) in their electrocardiograms (ECGs). Of these patients, 27 had suffered a myocardial infarction in the past and had been found to have a ventricular aneurysm (VA), documented by > or = 1 of several noninvasive and invasive diagnostic methods. Five of these 27 patients had stable ST-segment elevation in > or = 1 of left precordial ECG leads, with predominantly positive QRS complexes (an ECG criterion for the diagnosis of VA in the presence of LBBB, which we have recently described). ⋯ The frequency of distribution of VA in the septal, and even more, apical myocardial regions was higher in the patients with a positive ECG diagnosis of VA, than in the patients with a negative one (P = .049, and P = .009, correspondingly). The number of myocardial territories involved with a VA was not different in the 2 subgroups (P =.325). Pathophysiologically, this ECG alteration diagnostic of VA represents a superimposition of the primary ST-segment elevation due to the VA, on the expected secondary ST-segment depression due to the LBBB, and represents a summation effect.
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Sudden cardiac death accounts for 19% of sudden deaths in children between 1 and 13 years of age and 30% of sudden deaths that occur between 14 and 21 years of age. The incidence of sudden cardiac death displays 2 peaks: one between 45 and 75 years of age, as a result of coronary artery disease, and the other between birth and 6 months of age, caused by sudden infant death syndrome. The role of cardiac arrhythmias in sudden infant death syndrome has long been a matter of debate and the role of cardiac arrhythmias in children in general is not well defined. ⋯ Mass ECG screening of neonates and children however has been the subject of debate focused on issues ranging from the emotional impact of dealing with false positives to those concerning socio-economic and medico-legal factors. These issues are discussed in other articles. These concerns notwithstanding, it is important that we continue to question whether the economic inefficiencies of current screening methodologies supersede the value of a young life.
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Electrocardiogram variations (ECG) due to body position changes and electrode placements are common problems of continuous ST-T monitoring. Body position changes may cause QRS and ST-T changes and trigger false alarms. Placement of arm and leg electrodes in a coronary care unit environment is usually near the thorax instead of standard position at the wrists and ankles. This may affect the limb leads and complicate diagnostic interpretation. The purpose of this study was to assess the effects of these sources of ECG variation and to correct for them. Continuous 12-lead ECG recordings were obtained from 160 patients admitted to the coronary care unit. Each patient underwent a body position test (supine, left-lateral, and upright position). Scalar and spatial approaches were investigated for reconstruction of the ECG in supine position. The scalar approach uses linear regression. The spatial approach transforms the ECG into a derived vestorcardiogram. The spatial QRS-loop is then rotated and scaled to match the vector loop in supine position and transformed back to a 12-lead ECG. ⋯ Only 14% (23 of 160) of the patients showed marked ECG changes (ST elevations, QRS-axis shifts, T-wave inversions). The scalar method (median correlation > 0.994, SC > 0.902, QRS axis difference 0 degrees) performed better than spatial (median correlation 0.946, SC > 0.792, QRS axis difference 0 degrees). Monitoring leads can be mapped to standard limb leads in good to excellent approximaiton. General reconstruction (median correlation 0.993 and SC 0.764) performed slightly worse than patient-specific reconstruction (median correlation 0.997 and SC 0.908).