Chronic electrical performance of a new ultra-thin left ventricular quadripolar pacing lead

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): H2020-FTI [Fast Track to Innovation] Pilot-2016 and MicroPort CRM

Background

Left ventricular (LV) lead positioning is an important contributor to cardiac resynchronization therapy (CRT) response. Multiple additional LV sites could be stimulated by passing a new ultra-thin (1.2 Fr, 0.4 mm) quadripolar microlead from one LV vein into another via venous collaterals.

Purpose

Study the acute and chronic stability and electrical pacing performance of a novel 1.2 Fr quadripolar microlead ("Axone 4LV").

Methods

Seven healthy adult dogs underwent CRT defibrillator implantation, including a right ventricular lead and the microlead. The microlead was advanced into the coronary sinus network using a dedicated microguide catheter. The animals were followed up at 1, 15, 30 and 90 days post-implant to evaluate chronic stability and electrical pacing performance.

Results

Successful uncomplicated implantation was achieved in all cases. Despite the small diameter of the distal veins and collaterals, placement of the pacing electrodes in two different LV veins was feasible via available collateral passages. Lead position was stable in all cases and over the entire study period. Capture threshold and pacing impedance at 90 days post-implant were 1.7 ± 0.5 V with 1323 ± 245 Ω, respectively, at 0.5 ms pulse width. The mean pacing energy to get capture was 1.1 ± 0.5 µJ and less than 2 µJ in all cases (2 µJ ≈ 1.4 V @500 Ω, 0.5 ms). No phrenic nerve stimulation was observed during pacing.

Conclusions

The novel 1.2 Fr quadripolar microlead demonstrated adequate stability and good electrical performance allied to low energy consumption. This quadripolar microlead may extend pacing options while increasing device longevity in CRT. Changes in pacing parameters over time Post-implant Follow-up Pacing Threshold Pacing Impedance Pacing Energy 1 day 1.4 ± 0.7 V 1294 ± 270 Ω 0.8 ± 0.7 µJ 15 days 1.9 ± 0.9 V 1336 ± 274 Ω 1.8 ± 1.8 µJ 30 days 1.8 ± 0.7 V 1187 ± 303 Ω 1.5 ± 1.2 µJ 90 days 1.7 ± 0.5 V 1323 ± 245 Ω 1.1 ± 0.5 µJ

Oxidative stress-induced C/EBPβ inhibits β-catenin signaling molecule involving in the pathology of preeclampsia

INTRODUCTION

Oxidative stress-induced trophoblast cell dysfunction is a major pathology in preeclampsia (PE). Recently, CCAAT/enhancer binding protein beta (C/EBPβ) has been investigated as a tumor suppressor that participates in tumor invasion. However, the function of C/EBPβ in trophoblast cells remains unknown. Our study was designed to detect the expression of C/EBPβ in the preeclamptic placenta and to identify the underlying mechanisms of oxidative stress.

METHODS

Human placental tissues with PE were collected. The expression of C/EBPβ and β-catenin were detected. Human first trimester extravillous trophoblast cell (HTR8/SVneo) line exposed to hypoxia/reoxygenation (H/R) was employed as an oxidative stress model in vitro to investigate the effects of C/EBPβ on invasion and the expression of β-catenin. Moreover, first trimester-derived placental villous explants were used to verify the effects of C/EBPβ and β-catenin in placentation.

RESULTS

In preeclamptic placentas, C/EBPβ was overexpressed and β-catenin was decreased. In addition, C/EBPβ was found to have increased expression in H/R-treated HTR8/SVneo cells and villous explants. C/EBPβ knockdown and β-catenin activation could significantly promote the invasion of HTR8/SVneo cells, enhance the outgrowth and migration in villous explants and inhibit the excessive generation of intracellular ROS. These findings might be related to the increased activities of MMP-2/9 and the decreased expression of TIMP-1/2. Meanwhile, C/EBPβ knockdown remarkably increased the expression of β-catenin.

DISCUSSION

We hypothesize that the oxidative stress-induced overexpression of C/EBPβ might influence the activity of MMPs by regulating the Wnt/β-catenin signaling pathway to affect the invasion of trophoblast cells, which then participate in the pathogenesis of preeclampsia.

Knowledge discovery in clinical databases based on variable precision rough set model

Since a large amount of clinical data are being stored electronically, discovery of knowledge from such clinical databases is one of the important growing research area in medical informatics. For this purpose, we develop KDD-R (a system for Knowledge Discovery in Databases using Rough sets), an experimental system for knowledge discovery and machine learning research using variable precision rough sets (VPRS) model, which is an extension of original rough set model. This system works in the following steps. First, it preprocesses databases and translates continuous data into discretized ones. Second, KDD-R checks dependencies between attributes and reduces spurious data. Third, the system computes rules from reduced databases. Finally, fourth, it evaluates decision making. For evaluation, this system is applied to a clinical database of meningoencephalitis, whose computational results show that several new findings are obtained.

A newer avenue for evaluation of thyroid dysfunction

Attempt has been made to rationalise the biochemical assessment of patients suspected to have thyroid dysfunction by introduction of a new rapid and supersensitive immunoradiometric assay (IRMA) for TSH. 294 patients were subjected to thyroid investigation viz; tT3, tT4 and TSH (IRMA). Of these, 51 (17.34%) were hypothyroid, 22 (7.48%) were hyperthyroid and 221 (75.1%) were euthyroid. The ratio of thyroid disorder in male to female was 1:3.38. In all patients with hyperthyroidism TSH (IRMA) was 0.05 to undetectable and it was more than 4.5 ulu/ml in hypothyroid patients. TSH (IRMA) was low in one euthyroid patient a 0.34% incidence of false negativity. In 2 patients with subclinical hyperthyroidism TSH (IRMA) was low while tT3 and tT4 were normal. TSH (IRMA) therefore may obviate the need for more time consuming and expensive TRH test and simplify the approach to thyroid function tests in patients suspected to have masked or overt hyperthyroidism.