Journal of electrocardiology
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Combined sinoatrial and atrioventricular block is rare and has been reported in patients on digitalis. We report a case of combined Mobitz type II sinoatrial block and 2:1 atrioventricular block in a patient on no medication who presented with recurrent syncope.
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Measures of heart rate variability (HRV) can be divided in time domain and frequency domain parameters. It is frequently ignored that estimation of frequency-domain parameters is a 2-step procedure where statistical error from the first step (spectral estimation) is neglected in subsequent analyses. ⋯ Frequency domain parameters should be applied in HRV analysis only if important physiological reasons suggest their use. If used, frequency domain parameters should be interpreted with caution, taking into account the statistical weaknesses of spectral estimation.
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The correlation between ST-segment elevation (ST upward arrow) in lead V(3)R (ST upward arrow(V3R)), lead V(1) (ST upward arrow(V1)), and lead aVR (ST upward arrow(aVR)) during anterior wall acute myocardial infarction (AMI) and the culprit lesion site in the left anterior descending (LAD) coronary artery and the nature of the conal branch of the right coronary artery has not been thoroughly described. ⋯ In patients with anterior wall AMI, ST upward arrow(V3R) of at least 1 mm combined with ST upward arrow in leads V(2) through V(4) were strongly predictive of LAD occlusion proximal to S1; furthermore, ST upward arrow(aVR) and ST upward arrow(V1) of at least 2 mm were found to be useful in identifying LAD occlusion proximal to S1. ST upward arrow(aVR), ST upward arrow(V3R) of at least 1.5 mm, and ST upward arrow(V1) of at least 2.0 mm were also associated with the presence of a small conal branch not reaching the intraventricular septum during anterior wall AMI.
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The aim of this study was to develop and evaluate transformation coefficients for deriving the standard 12-lead electrocardiogram (ECG), 18-lead ECG (with additional leads V7, V8, V9, V3R, V4R, V5R), and Frank vectorcardiogram (VCG) from reduced lead sets using 3 "limb" electrodes at Mason-Likar torso sites combined with 2 chest electrodes at precordial sites V1 to V6; 15 such lead sets exist and each can be recorded with 6-wire cable. As a study population, we used Dalhousie Superset (n = 892) that includes healthy subjects, postinfarction patients, and patients with a history of ventricular tachycardia. For each subject, 120-lead ECG recordings of 15-second duration were averaged, and all samples of the QRST complex for leads of interest were extracted; these data were used to derive--by regression analysis--general and patient-specific coefficients for lead transformations. ⋯ Our results show that the best pair for predicting the standard 12-lead ECG by either general coefficients (mean SC = 95.56) or patient-specific coefficients (mean SC = 99.11) is V2 and V4; the best pair for deriving the 18-lead set by general coefficients (mean SC = 93.74) or by patient-specific coefficients (mean SC = 98.71) is V1 and V4; the best pair for deriving the Frank X, Y, Z leads is V1 and V3 for general coefficients (mean SC = 95.76) and V3 and V6 for patient-specific coefficients (mean SC = 99.05). The differences in mean SC among the first 8 to 10 predictor sets in each ranking table are within 1% of the highest SC value. Thus, in conclusion, there are several near-equivalent choices of reduced lead set using 6-wire cable that offer a good prediction of 12-lead/18-lead ECG and VCG; a pair most appropriate for the clinical application can be selected.
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We report 2 patients in whom transient marked QT prolongation occurred after successful emergent percutaneous coronary intervention (PCI) for acute coronary syndrome. One patient developed torsades de pointes. In both cases, the QT interval became markedly prolonged within 24 hours after PCI, and this prolongation persisted for 4 days. ⋯ No new-onset ischemia or congenital long QT syndrome was related to the episodes. The patients had not taken any drugs that could have prolonged the QT interval, and their serum potassium levels were within normal limits. Torsades de pointes following successful PCI for acute coronary syndrome is uncommon, but acquired long QT syndrome should be considered and treated in patients in whom giant and bizarre negative T waves and QT prolongation develop after PCI.