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Increased hs-CRP and decreased 1,25-dihydroxyvitamin D are associated with increased left ventricle lead threshold.
Gözübüyük, G, Koç, M, Kaypaklı, O, Şahin, DY
Journal of interventional cardiac electrophysiology : an international journal of arrhythmias and pacing. 2016;(2):177-183
Abstract
PURPOSE There are not enough data about threshold changes in patients with CRT. In this study, we aimed to investigate frequency of significant threshold increase of left ventricle lead and to determine clinical, demographic, medical and laboratory parameters that associated with threshold increase in CRT implanted patients. METHODS We included CRT implanted 200 patients (124 males, 76 females; mean age 65.8 ± 10.3 years) to this study. Basal and third month LV R wave amplitude, electrode impedance, and threshold values were recorded. Threshold increase was accepted as ≥0.1 V and significant increase as >1 V. Patients were divided into two groups: increased threshold and non-increased threshold for LV lead. RESULTS Number of patients with increased LV threshold was 68 (37.6 %). Furthermore, 8 % of patients had severe increase (≥1 V) in LV threshold. We observed that serum levels of hs-CRP and 1,25 (OH)2 vitamin D were independently associated with increased LV threshold. We showed that 1 mg/dl increase in hs-CRP and the 1 mg/dl decrease in vitamin D are associated with 25.3 and 4.5 % increase in the odds of increased LV threshold, respectively. CONCLUSIONS Increased hs-CRP and decreased 1,25 (OH)2 vitamin D are the strongest predictors of increased LV lead thresholds. We suggest that hs-CRP and 1,25 (OH)2 vitamin D may be used as markers to predict and follow the patients with increased thresholds. It may be useful to finalize CRT procedure with more appropriate basal threshold in patients with high serum hs-CRP and low 1,25 (OH)2 vitamin D levels.
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Response of QT interval in methadone maintenance treated patients to the rapid changes in heart rate provoked by brisk standing: comparison to healthy controls and patients with long QT syndrome.
Ben Bassat, OK, Peles, E, Schreiber, S, Adelson, M, Zeltser, D, Viskin, S, Adler, A
Journal of electrocardiology. 2013;(6):519-23
Abstract
BACKGROUND Patients on methadone maintenance therapy are somehow similar to patients with congenital long QT syndrome (LQTS) because they have malfunction of potassium channels caused by a drug that cannot be easily discontinued. We tested patients on methadone therapy with the "stand-up" test, which has been shown to unravel pathologic QT-prolongation in congenital long-QT patients. METHODS "Stand-up" test results of methadone-users, healthy volunteers and congenital LQTS patients were compared. Methadone serum levels and doses were collected. The prognostic value of the test was evaluated after 4 years of follow-up. RESULTS The QT-response of methadone-users to the "stand-up" test resembled that of healthy volunteers more than the response of LQTS-patients. Differences in the QTc of methadone treated patients and controls, which were statistically significant at baseline, became no longer significant after standing. Within 52 months of follow-up, one patient had suffered unexplained death and one had documented ventricular tachycardia. CONCLUSIONS The QT-response of methadone-users to the "stand-up" test is similar to that of healthy volunteers, not to that of LQTS-patients.
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Variability of repeated coronary artery calcium measurements by 1.25-mm- and 2.5-mm-thickness images on prospective electrocardiograph-triggered 64-slice CT.
Horiguchi, J, Matsuura, N, Yamamoto, H, Hirai, N, Kiguchi, M, Fujioka, C, Kitagawa, T, Kohno, N, Ito, K
European radiology. 2008;(2):209-16
Abstract
High reproducibility on coronary artery calcium scoring is a key requirement in monitoring the progression of coronary atherosclerosis. The purpose of this prospective study is to assess the reproducibility of 1.25-mm- and 2.5-mm-thickness images on prospective electrocardiograph-triggered 64-slice CT with respect to 2.5-mm-thickness images on spiral overlapping reconstruction. One hundred patients suspected of coronary artery disease were scanned twice repeatedly, both on prospective electrocardiograph-triggered step-and-shoot and retrospective electrocardiograph-gated spiral scans. Using 1.25-mm-thickness collimation, 1.25-mm- and 2.5-mm-thickness image sets on prospective scans and 2.5-mm-thickness image sets with 1.25-mm increment (overlapping) on retrospective scans were obtained. Coronary artery calcium scores, interscan variability and interobserver variability were evaluated. The mean interscan variability in coronary artery calcium measurement on 1.25-mm prospective/2.5-mm prospective/2.5-mm overlapping retrospective scans were Agatston: 10%/18%/12%, volume: 10%/12%/10% and mass: 8%/13%/11% for observer 1 and Agatston: 8%/14%/10%, volume: 7%/9%/10% and mass: 7%/10%/9% for observer 2, respectively. The mean interobserver variability was 5% to 14%. In conclusion, prospective electrocardiograph-triggered 64-slice CT using the 1.25-mm prospective scan shows the lowest variability. The 2.5-mm prospective scan on volume or mass scoring shows variability of around 10%, comparable to 2.5-mm-thickness spiral overlapping reconstruction images.
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Intravenous magnesium sulfate enhances the ability of intravenous ibutilide to successfully convert atrial fibrillation or flutter.
Tercius, AJ, Kluger, J, Coleman, CI, White, CM
Pacing and clinical electrophysiology : PACE. 2007;(11):1331-5
Abstract
BACKGROUND A previous randomized trial found that adjunctive use of intravenous magnesium (a total of 4 grams) can attenuate the corrected QT interval (QTc) prolongation associated with ibutilide, but its impact on ibutilide efficacy has not been elucidated. METHODS This was a cohort evaluation of 229 consecutive patients who received ibutilide in the presence or absence of intravenous magnesium. Multivariate logistic regression analysis was used to determine the impact of magnesium on ibutilide efficacy as well as the impact of magnesium dosing intensity on ibutilide efficacy. RESULTS The overall chemical conversion rate with ibutilide in the presence or absence of magnesium was 59.8%. The concurrent administration of magnesium (n = 141) was associated with a 78% increased odds of successful chemical conversion (adjusted odds ratio, AOR; 1.78 [95% confidence intervals,CI 1.02-3.09]) compared to those who did not receive magnesium (n = 88). Magnesium dosing intensity appeared to be an important determinant of ibutilide efficacy, with the 4 grams dose associated with a threefold increase in the odds of successful chemical conversion (AOR; 2.98 [95% CI 1.46-6.11). The 1 to 3 grams subgroup was associated with only a trend toward an improvement. There was only one case of Torsade de Pointes (TdP) which occurred in the no adjunctive magnesium group. CONCLUSIONS Concurrent use of magnesium enhanced the ability of ibutilide to successfully convert atrial fibrillation (AF) or flutter (AFl). The 4 grams magnesium dose appeared to provide the greatest benefit.
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Assessment of markers for identifying patients at risk for life-threatening arrhythmic events in Brugada syndrome.
Ajiro, Y, Hagiwara, N, Kasanuki, H
Journal of cardiovascular electrophysiology. 2005;(1):45-51
Abstract
INTRODUCTION Risk stratification for life-threatening arrhythmic events in Brugada syndrome is not yet established. The aim of the present study was to examine the usefulness of various markers in predicting life-threatening arrhythmic events in the Brugada syndrome. METHODS AND RESULTS Forty-six patients with Brugada-type ECGs were categorized into the symptomatic (n=28) and asymptomatic (n=18) groups. Statistical analyses were performed with respect to the usefulness of the following markers: SCN5A mutation, pharmacologic challenge, ventricular fibrillation (VF) inducibility by programmed electrical stimulation, and late potential (LP) by signal-averaged ECG (SAECG). Comparison between the two groups revealed a significant difference only in LP positivity (92.6% vs 47.1%, P=0.0004). The symptomatic group had significantly lower RMS40, longer LAS40, and longer fQRSd compared with the asymptomatic group. A significant difference was noted, especially RMS40. The positive predictive value, negative predictive value, and predictive accuracy when setting a cutoff value of 15 microV were 92.0%, 78.9%, and 86.4%, respectively. Furthermore, patients with an RMS40 value <15 microV (n=25) showed significantly higher rates of VF recurrence compared with patients with an RMS40 value > or = 15 microV (n=19, P=0.047). CONCLUSION Regarding risk stratification for identifying high-risk patients in Brugada syndrome, only LP by SAECG was shown to be useful, suggesting the importance of RMS40 in predicting the history of life-threatening arrhythmic events and the recurrence of VF.
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Spectral analysis of heart rate variability in premature infants with feeding bradycardia.
Veerappan, S, Rosen, H, Craelius, W, Curcie, D, Hiatt, M, Hegyi, T
Pediatric research. 2000;(5):659-62
Abstract
An elevated level of baseline parasympathetic activity was noted in a group of premature infants suffering from bradycardia during feeding. At approximately 34 wk post-conceptional age, the heart rates of 12 infants with feeding bradycardia (birth weight = 1539 +/- 279 g; gestational age = 31.0 +/- 1.6 wk) and 10 controls (birth weight = 1710 +/- 304 g; gestational age = 32.0 +/- 1.4 wk) were recorded 1 h before and 1 h after feeding. EKG data were digitized and 3.2-min segments of data were analyzed to determine the spectral power at very low (VLF = 0.003-0.03 Hz), low (LF = 0.03-0.39 Hz), and high (HF = 0.40-1.00 Hz) frequencies. In preterm infants with feeding bradycardia, an elevation in baseline parasympathetic activity was evident before feeding, as indicated by significantly higher HF power and a lower LF/HF ratio. This elevation in baseline parasympathetic activity may contribute to the observed bradycardia during feeding.
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Effect of sodium channel blockers on ST segment, QRS duration, and corrected QT interval in patients with Brugada syndrome.
Shimizu, W, Antzelevitch, C, Suyama, K, Kurita, T, Taguchi, A, Aihara, N, Takaki, H, Sunagawa, K, Kamakura, S
Journal of cardiovascular electrophysiology. 2000;(12):1320-9
Abstract
INTRODUCTION Brugada syndrome is characterized by an ST segment elevation in leads V1-V3 and a high incidence of ventricular fibrillation (VF). A mutation in a cardiac Na+ channel gene, SCN5A, has been linked to Brugada syndrome, and sodium channel blockers have been shown to be effective in unmasking the syndrome when concealed. The aim of this study was to examine the effects of Na+ channel blockers on ST segment elevation, QRS, corrected QT (QTc) interval, and ventricular arrhythmias in patients with Brugada syndrome. METHODS AND RESULTS We examined the effects of three different Na+ channel blockers (flecainide, disopyramide, and mexiletine) on the amplitude of the ST segment 20 msec after the end of QRS (ST20), QRS duration, QTc interval measured from 12-lead ECG, and ventricular arrhythmias in 12 Brugada and 10 control patients. Maximum ST20 observed in the V2 or V3 leads under baseline conditions was greater in the Brugada patients than in control patients, whereas QRS duration and maximum QTc interval were no different between the two groups. Flecainide and disopyramide, but not mexiletine, significantly increased maximum ST20 and QRS duration in both groups, although these effects were much more pronounced in the Brugada patients. The increases in ST20 and QRS duration with flecainide were significantly larger than those with disopyramide. An increase of 0.15 mV in ST20 with flecainide separated the two groups without overlap. Ventricular premature complexes developed only with flecainide in Brugada patients (3/12) displaying a marked ST elevation but not widening of QRS. CONCLUSION Our findings suggest that Na+ channel blockers amplify existing I(Na) and possibly other ion channel defects, with a potency inversely proportional to the rate of dissociation of the drug from the Na+ channel, thus causing a prominent elevation of the ST segment and, in some cases, prolongation of QRS duration in patients with Brugada syndrome.