Continuing Medical Education Activity in Echocardiography

Article Title: Different Mechanisms for Diastolic Mitral Regurgitation Illustrated by Three Comparative Cases
(Echocardiography 2011;28:475)     

Innovations in Cardiac Implantable Electronic Devices

Cardiovascular Drugs and Therapy - Cardiac implantable electronic devices (CIEDs) are essential for the management of a variety of cardiac conditions, including tachyarrhythmias, bradyarrhythmias,...     

Changes in mitral valve geometry after percutaneous valve repair with the MitraClip® System

The International Journal of Cardiovascular Imaging - The aim of our study was to assess the anatomical changes of the mitral valve apparatus after percutaneous repair with the MitraClip®...     

Functional characterization of genetically labeled gonadotropes

Gonadotropes are crucial in the control of reproduction but difficult to isolate for functional analysis due to their scattered distribution in the anterior pituitary gland. We devised a binary genetic approach, and describe a new mouse model that allows visualization and manipulation of gonadotrope cells. Using gene targeting in embryonic stem cells, we generated mice in which Cre recombinase is coexpressed with the GnRH receptor, which is expressed in gonadotrope cells. We show that we can direct Cre-mediated recombination of a yellow fluorescent protein reporter allele specifically in gonadotropes within the anterior pituitary of these knock-in mice. More than 99% of gonadotropin-containing cells were labeled by yellow fluorescent protein fluorescence and readily identifiable in dissociated pituitary cell culture, allowing potentially unbiased sampling from the gonadotrope population. Using electrophysiology, calcium imaging, and the study of secretion on the single-cell level, the functional properties of gonadotropes isolated from male mice were analyzed. Our studies demonstrate a significant heterogeneity in the resting properties of gonadotropes and their responses to GnRH. About 50% of gonadotropes do not exhibit secretion of LH or FSH. Application of GnRH induced a broad range of both electrophysiological responses and increases in the intracellular calcium concentration. Our mouse model will also be able to direct expression of other Cre recombination-dependent reporter genes to gonadotropes and, therefore, represents a versatile new tool in the understanding of gonadotrope biology.     

A New Tissue Doppler Index to Predict Cardiac Death in Patients with Heart Failure

Background

It has been shown that a new tissue Doppler index, E/(E''×S''), including the ratio between early diastolic transmitral and mitral annular velocity (E/E''), and the systolic mitral annular velocity (S''), has a good accuracy to predict left ventricular filling pressure.

Objectives

We investigated the value of E/(E''×S'') to predict cardiac death in patients with heart failure.

Methods

Echocardiography was performed in 339 consecutive hospitalized patients with heart failure, in sinus rhythm, after appropriate medical treatment, at discharge and after one month. Worsening of E/(E''×S'') was defined as any increase of baseline value. The end point was cardiac death.

Results

During the follow-up period (35.2 ± 8.8 months), cardiac death occurred in 51 patients (15%). The optimal cut-off value for the initial E/(E''×S'') to predict cardiac death was 2.83 (76% sensitivity, 85% specificity). At discharge, 252 patients (74.3%) presented E/(E''×S'') ≤ 2.83 (group I) and 87 (25.7%) presented E/(E''×S'') > 2.83 (group II), respectively. Cardiac death was significantly higher in group II than in group I (38 deaths, 43.7% vs 13 deaths, 5.15%, p < 0.001). By multivariate Cox regression analysis, including variables that affected outcome in univariate analysis, E/(E''×S'') at discharge was the best independent predictor of cardiac death (hazard ratio = 3.09, 95% confidence interval = 1.81-5.31, p = 0.001). Patients with E/(E''×S'') > 2.83 at discharge and its worsening after one month presented the worst prognosis (all p < 0.05).

Conclusions

In patients with heart failure, the E/(E''×S'') ratio is a powerful predictor of cardiac death, particularly if it is associated with its worsening.     

The risk of tuberculosis in transplant candidates and recipients: a TBNET consensus statement

Tuberculosis (TB) is a possible complication of solid organ and hematopoietic stem cell transplantation. The identification of candidates for preventive chemotherapy is an effective intervention to protect transplant recipients with latent infection with Mycobacterium tuberculosis from progressing to active disease. The best available proxy for diagnosing latent infection with M. tuberculosis is the identification of an adaptive immune response by the tuberculin skin test or an interferon-γ based ex vivo assay. Risk assessment in transplant recipients for the development of TB depends on, among other factors, the locally expected underlying prevalence of infection with M. tuberculosis in the target population. In areas of high prevalence, preventive chemotherapy for all transplant recipients may be justified without immunodiagnostic testing while in areas of medium and low prevalence, preventive chemotherapy should only be offered to candidates with positive M. tuberculosis-specific immune responses. The diagnosis of TB in transplant recipients can be challenging. Treatment of TB is often difficult due to substantial interactions between anti-TB drugs and immunosuppressive medications. This management guideline summarises current knowledge on the prevention, diagnosis and treatment of TB related to solid organ and hematopoietic stem cell transplantation and provides an expert consensus on questions where scientific evidence is still lacking.     

Intrinsic Dielectric Loss in Zr0.8Sn0.2TiO4 Ceramics Investigated by Terahertz Time Domain Spectroscopy

Terahertz time-domain spectroscopy (THz-TDS) was employed for estimation of intrinsic dielectric loss of Zr_0.8Sn_0.2TiO₄ (ZST) ceramics. Single-phase ZST dielectric resonators (DRs) with various synthesis parameters and, consequently, different extrinsic losses, were prepared by conventional ceramic technology. Even though the DRs exhibit a similar microstructure, their quality factor (Q is the inverse of dielectric loss tangent) measured in microwave (MW) domain at 6 GHz varies between 2500 and 8400. On the other hand, it was found that the THz dielectric loss is less sensitive to the sample preparation. The intrinsic losses (Q × f ~60 THz) of the ZST ceramics have been derived from THz data.