6117Persistent LBBB and AV block with high-burden RV pacing following transcatheter aortic valve replacement are associated with new onset cardiomyopathy

Background

Left bundle branch block (LBBB) and AV nodal block (AVB) requiring permanent pacemaker implantation occur frequently following transcatheter aortic valve replacement (TAVR) and may be associated with adverse clinical events.

Objectives

The study aims to assess the incidence of new onset cardiomyopathy among patients with normal left ventricular systolic function patients who developed LBBB or persistent AVB with high-burden right ventricular (RV) pacing (>80%) following TAVR procedure.

Methods

Consecutive patients who underwent TAVR procedure from January 2012 to June 2017 at the University of Michigan Health System were included in the retrospective analysis. Those who had a preexisting cardiac implantable electronic device (CIED), prior LBBB, left ventricular ejection fraction (LVEF) <50%, and follow up period less than 1 year were excluded from this analysis. New onset cardiomyopathy was defined by a left ventricular ejection fraction (LVEF) <45% within 1 year after TAVR.

Results

A total of 362 patients were included in the study (mean age 76.9±11.5 years, 56.1% male). Of these, 30 patients (8.3%) developed persistent AVB and required >80% RV pacing (pacing group), 61 patients (16.9%) developed persistent LBBB (LBBB group), and 271 patients (74.9%) did not have LBBB or AVB or required <80% RV pacing (control group). Baseline LVEF was 63.9+6.4% in pacing group (p=0.76) and 64.4+7.4% in LBBB group (p=0.89) compared to 64.3+6.5% in control group. Within 1 year after TAVR, 10/30 patients (33.3%) in pacing group (p<0.01) and 20/61 patients (32.8%) in LBBB (p<0.01) developed new onset cardiomyopathy compared to 9/271 patients (3.3%) in control group. LVEF at 1 year was 53.8+11.9% in pacing group (p<0.01) and 53.7+12.1% in LBBB group (p<0.01) compared to 64.8+7.7% in control group.

Conclusion

Among patients with normal baseline left ventricular systolic function, AV block required high-burden RV pacing and persistent LBBB following TAVR were associated with significantly higher incidence of new onset cardiomyopathy.

Microwave Non-Destructive Inspection and Prediction of Modulus of Rupture and Modulus of Elasticity of Engineered Cementitious Composites (ECCs) Using Dual-Frequency Correlation

This research article presents dual-frequency correlation models for predicting the growth of elasticity and flexural strength of engineered cementitious composites (ECCs) using microwave nondestructive inspection technique. Parallel measurements of microwave properties and mechanical properties of ECC specimens were firstly undertaken in the sense of cross-disciplinary experiments. Regression models were developed via means of nonlinear regression to the measured data. The purpose of the study is: (i) to monitor the flexural strength and elasticity growth; and (ii) to predict their mature values under the influence of different initial water contents, via microwave effective conductance at early ages. It has been demonstrated that both the modulus of rupture (MOR) and modulus of elasticity (MOE) can be accurately modeled and correlated by microwave conductance using exponential functions. The moduli developed as a function of conductance whereas the regression coefficient exhibited a linear relation with water-to-binder ratio. These findings have highlighted the effectiveness of the microwave non-destructive technique in inspecting the variation of liquid phase morphology of ECCs. The dual-frequency correlation can be used for structural health monitoring, which is not only for prediction but also provides a means of verification.

Prediction of violence on a psychiatric intensive care unit

The aim of the present study was to identify patients who were at particular risk of violent behaviour, over a period of one month in a psychiatric high dependency unit, and to examine whether particular patients could be identified at admission who would subsequently be violent. Medical records, and other documents for 52 inpatients were included. Demographic, historical and clinical data available at admission were noted. All violent incidents were recorded and classified. Seventeen of 52 patients committed physical violence, usually to the staff. Most incidents were carried out by a small number of individuals. Identifying the violent, using variables available at admission, was not possible. The ward admitted a group with a subsequent high rate of violence. Prediction within this high-risk group was not possible. Measures aimed at preventing violence on a local secure ward should apply to all patients and should not be targeted just at those that would appear to be the most likely to be violent.

Neutron activation of iron tablets to evaluate the effects of glycine on iron absorption

Neutron bombardment (neutron flux, 3 X 10(12) neutrons/cm2/s) of prepared iron tablets containing glycine-iron or iron alone was performed to prepare radioactive tablets to assess the effects of glycine on iron absorption from tableted formulations. No interfering isotopes of sufficient quantity were generated during neutron activation of the iron tablets. Cobalt-60 was the major trace mineral detected and accounted for only 1.3% of the total activity. There may have been trace amounts of zinc-65 or chromium-51 present, but they were not detectable above background radioactivity in the final tablet produced. Iron-59 represented greater than 98% of the radioactivity present in the tablets used in the study. Glycine-containing iron tablets produced dramatically higher amounts of iron in blood and tissues of rabbits (p less than 0.05) than did the same tablet formulations without glycine. The area under the iron blood concentration-time curve over 4 h increased by 67% with glycine added to the formulation over control iron tablets. Iron concentrations in tissues 4 h after iron administration was in the order of blood greater than liver greater than heart greater than kidney greater than muscle.

Effects of divalent amino acids on iron absorption

Solutions of each of 10 amino acids or ascorbic acid were mixed with iron and orally administered to rats. Iron was absorbed to a statistically significantly greater extent (p less than 0.05) when mixed with asparagine, glycine, serine, or ascorbic acid as compared with a control solution of iron. The largest effects were for asparagine and glycine, which also increased iron absorption to a significantly greater extent (p less than 0.001) than did serine or ascorbic acid. No statistically significant increase in iron absorption occurred when any of the other amino acids was mixed with iron. The extent of iron absorption from each test solution, as measured by area under the concentration of iron-59 in the blood-time curve (r2 = 0.0002), and the initial rate of iron absorption for each test solution (r2 = 0.01) showed no correlation with the stability constant of the amino acid-iron complex.