T Wave Alternans in Idiopathic Long-QT Syndrome: Insight from Body Surface Mapping

Body surface mapping was recorded during T wove alternans in two patients with idiopathic long QT syndrome. Eighty-seven had ECGs of two consecutive beats during T wave alternans demonstrated that alternating changes in the morphology and polarity of the T wave existed mainly in the left frontal chest. The QRST isointegral maps of the same two consecutive beats showed alternation of a large negative area appearing mainly in the left frontal chest. These results indicate that T wave alternans in the two patients were related to alternate heterogeneous prolongation of the action potential duration in this region.     

INDUCTION OF SIALYL LEWISX ON THE SURFACE OF CULTURED RAT VASCULAR ENDOTHELIAL CELLS AND CARDIAC MYOCYTES BY HYPOXIA/REOXYGENATION IN VITRO

Neutrophils adhere to and roll on vascular endothelial cells (VECs) through interaction of selectins and their carbohydrate ligands in the early stages of inflammation; this adhesion is then later strengthened through interaction of integrins on neutrophils with intercellular adhesion molecule-1 (ICAM-1) on endothelial cells. Recent, as yet unpublished studies showed that myocardial ischaemia/reperfusion caused rapid expression of sialyl Lewis^X (SLe^X), one of the carbohydrate ligands of selectins, on VECs and cardiac myocytes and that an anti-SLe^X monoclonal antibody (MAb) significantly reduced myocardial reperfusion injury in vivo . In the present study, to investigate whether or not ischaemia/reperfusion itself can induce the expression of SLe^X on VECs and cardiac myocytes, the expression of SLe^X on cultured rat VECs and cardiac myocytes was examined by treatment with hypoxia/reoxygenation in vitro , because ischaemia/reperfusion stimuli may partly be due to hypoxia/reoxygenation. The expression of SLe^X was induced rapidly and temporarily on the surface of cultured rat cardiac myocytes and VECs by hypoxia/reoxygenation in vitro . This strongly suggests that the expression of SLe^X on the surface of myocardial cells is induced initially and directly by ischaemia/reperfusion, which results in the rolling attachment of neutrophils in the early stages of myocardial reperfusion injury.     

Biventricular Shocking Leads Improve Defibrillation Efficacy

INTRODUCTION: A single lead active can configuration has been widely used in patients with life-threatening ventricular arrhythmias. Occasionally, however, such a defibrillation lead configuration may not achieve adequate defibrillation threshold (DFT). The purpose of this study was to determine whether addition of a left ventricular (LV) lead can improve defibrillation efficacy. METHODS AND RESULTS: Three transvenous defibrillation leads (8.3-French with a 5-cm long unipolar coil) were placed in the right ventricle (RV), LV, and superior vena cava (SVC), along with an active can (92 cm2) in the left subpectoral area. The DFT stored energy of seven combinations of these defibrillation leads were compared in a pig ventricular fibrillation model using a biphasic defibrillation waveform (125 microF, 6.5/3.5 msec). A biventricular leads active can configuration in which the RV and LV leads were of the same polarity reduced the DFT stored energy by approximately 35% when compared to a single RV lead active can configuration (9.6 +/- 3.0 J vs 15.0 +/- 7.2 J, respectively, P = 0.02). Moreover, adding a SVC lead further reduced the DFT energy (8.4 +/- 3.3 J). CONCLUSION: A biventricular leads active can configuration can significantly improve defibrillation efficacy as compared to a single lead active can configuration. In such a defibrillation lead configuration, the polarity of RV and LV leads should be the same.     

Effects of Respiration Phase on Ventricular Defibrillation Threshold in a Hot Can Electrode System

The impedance of defibrillation pathways is an important determinant of ventricular defibrillation efficacy. The hypothesis in this study was that the respiration phase (end-inspiration versus end-expiration) mayalter impedance and/or defibrillation efficacy in a "hot can" electrode system. Defibrillation threshold (DFT) parameters were evaluated at end-expiration and at end-inspiration phases in random order by a biphasic waveform in ten anesthetized pigs (body weight: 19.1 ±2.4 kg; heart weight: 97 ± 10g). Pigs were intubated with a cuffed endotracheal tube and ventilated through a Drager SAVrespirator with tidal volume of 400–500 mL. A transvenous defibrillation lead (6 cm long, 6.5 Fr) was inserted into the right ventricular apex. A titanium can electrode (92-cm² surface area) was placed in the left pectoral area. The right ventricular lead was the anode for the first phase and the cathode for the second phase. The DFT was determined by a "down-up down-up" protocol. Statistical analysis was performed with a Wilcoxon matched pair test. The median impedance at DFT for expiration and inspiration phases were 37.8 ±3.1 Ω and 39.3 ± 3.6 Ω, respectively (P = 0.02). The stored energy at DFT for expiration and inspiration phases were 5.7 ± 1.9 J and 6.0 ± 1.0 J, respectively (P = 0.594). Shocks delivered at end-inspiration exhibited a statistically significant increase in electrode impedance in a "hot can" electrode system. The finding that DFT energy was not significantly different at both respiration phases indicates that respiration phase does not significantly affect defibrillation energy requirements.     

Alteration of esophageal pressure in sleep-disordered breathing

Abstract We investigated the alteration of esophageal pressure (Pes) in 10 patients with upper-airway sleep-disordered breathing (UASDB) and the relationship among Pes, breathing patterns and EEG arousals. Increased negative Pes without apnea or hypopnea, appeared not only in upper airway resistance syndrome but also in obstructive sleep apnea syndrome. This phenomenon produced frequent EEG microarousals leading to sleep fragmentation and daytime sleepiness. Moreover, increased negative Pes occasionally continued for more than 20 min without an EEG arousal, which might be considered to be one of the factors to cause complications of UASDB.     

Analysis of the 13C-urea breath test for detection of Helicobacter pylori infection based on the kinetics of Δ-13CO2 using laser spectroscopy

We have previously reported on laser spectroscopy as a simple alternative to mass spectrometry. To validate a simplified ¹³C-urea breath test (UBT) with laser spectroscopy for the detection of Helicobacter pylori in clinical use, we evaluated the optimal time of breath sample collection. The ¹³C-UBT was carried out on each of 102 infected and 70 non-infected subjects (32 without eradication and 38 after eradication therapy). Breath samples were taken at five time points within 60 min followed by 100 mg of ¹³C-urea administration. The ratio of ¹³CO₂ to ¹²CO₂ was measured using laser spectroscopy and the recovery of tracer in the exhaled breath was calculated. Results were compared with histological and culture examinations of gastric biopsies to establish the infection status. For statistical evaluation of ¹³C-UBT, the optimal timing of breath sample collection was examined on the basis of the kinetics of Δ-¹³CO₂. In 32 H. pylori-negative patients (without therapy), the mean ± 2SD of Δ-¹³CO₂ was at its minimum 20 min after urea ingestion whereas in H. pylori-positive patients, the mean ± SD Δ-¹³CO₂ was maximum at 20 min. In addition, receiver operating characteristic (ROC) curve analysis showed that the cut-off value was estimated between 2.5–3.0 per mil (‰) at 20 min before therapy. Based on the histology and culture results, the sensitivity, specificity and positive and negative predictive values were 98.0%, 100%, 100% and 94.1%, respectively. In conclusion, ¹³C-UBT with laser spectroscopy is a non-invasive, simple, sensitive and specific test to determine H. pylori status. Our findings suggest that in clinical use, measurements made at 20 min after substrate administration could be recommended for most sensitive and specific ¹³C-UBT results.     

Modified endoscopic live donor nephrectomy: Retroperitoneoscopy followed by hand-assistance

We have developed a novel modification of previous approaches to donor nephrectomy and herein review our original operative procedure. First, the posterior aspect of the kidney was dissected retroperitoneoscopically and dissection of the renal artery, ureter and gonadal vein was almost completed. Second, the anterior aspect of the kidney was dissected with transperitoneal hand-assistance, and dissection of the renal pedicle from the anterior surface was accomplished easily and safely. This operative procedure was successfully performed for two donors with no intraoperative or postoperative complications. Our modified endoscopic donor nephrectomy is feasible as a minimally invasive procedure because of its safety, and its ability to preserve renal function and establish an excellent operative field for both posterior and anterior aspects of the kidney.