Influence of pacemaker leads on the severity of tricuspid regurgitation after successful mitral valve edge to edge repair

Background

After percutaneous mitral-valve edge-to-edge repair (MVER) for mitral regurgitation (MR) in patients with baseline tricuspid regurgitation (TR), about one third of patients shows improvement in TR severity. It is unknown whether this improvement may depend on the presence of a right ventricular (RV) pacemaker (PM) lead.

Aim

We investigated whether the presence of an existing RV PM lead influences TR severity after successful MVER due to symptomatic secondary MR.

Methods and results

We retrospectively analyzed 115 consecutive patients with symptomatic secondary high-grade MR (age 78.1±9.4 years, 50 women (43%) and baseline TR grade > or =1 (semiquantitative grading from 0 to 5) treated with MVER using the MitraClipTM device (Abbott, Cardiovascular, USA) and separated them in 2 groups, 43 patients with a PM lead compared to 72 pts without (see Table). TR grading by echocardiography was performed before and 3 months after MVER. (median follow up duration was 3 months). Procedural success with reduction of MR to < or =2/4 grades was 100% in both groups (p<0,001 vs. baseline). There was an overall significant change in TR grade after MVER in 46 pts (p 0,032): but both increase in TR in 17 pts (16.7%, p=0.58), in 10 pts with and in 7 pts without PM lead (58.8% vs. 41.2%, respectively; p=0.84) was not significant; the decrease in TR in 29 patients (28.4%, p=0.57), in 20 pts with and in 9 pts without PM lead (69% and 31%, respectively; p=0.47) also failed to reach statistical significance. TR reduction was associated with RV dilatation at baseline (p=0.006) but not the presence of pulmonary hypertension (p=0.83).

Conclusion

There was an overall significant change in TR after successful MVER. Although there was a trend towards an increase in TR after MVER in pts with PM lead there was no overall significant correlation between changes in TR severity and the presence of an RV PM lead but rather with baseline RV dilatation.

Funding Acknowledgement

Type of funding sources: None.

Optimization of nitrogen source supply for enhanced biosynthesis and quality of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by extremely halophilic archaeon Haloferax mediterranei

The extreme halophilic archaeon, Haloferax mediterranei can accumulate polyhydroxyalkanoate (PHA) from different renewable resources. To enhance the biosynthesis and quality of PHA, H. mediterranei cultivation media was optimized at different C/N ratios using glucose as the main carbon source. Three sets of media (yeast extract [YE], NH₄ Cl and combination of YE and NH₄ Cl) were prepared at different nitrogen concentrations to achieve C/N ratios of 9, 20, and 35, respectively. The media containing YE (organic nitrogen source) produced a higher growth rate of H. mediterranei than NH₄ Cl (inorganic source) at all tested C/N ratios. The highest PHA accumulation (18.4% PHA/cell dry mass) was achieved in a media that combined YE with NH₄ Cl at a C/N ratio of 20. Analysis of the produced polymers revealed the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) with different 3-hydroxyvalerate (3HV) content. The polymers produced from YE and the combined media have greater 3HV content (10 mol%) than those polymers recovered from NH₄ Cl (1.5 mol%). Resultingly, PHBHV from YE and the combined media displayed reduced melting points at 144°C. The nitrogen type/concentration was found to also have an impact on the molecular weights and polydispersity indices of the produced biopolymers. Furthermore, the tensile strengths were found to vary with the best tensile strength (14.4 MPa) being recorded for the polymer recovered from YE at C/N = 9. Interestingly, the tensile strength of PHBHV was significantly higher than petroleum-based polyethylene (13.5 MPa), making it a much more suitable bioplastic for industrial application.

Glass Transitions in Lubricants: Its Relation to Elastohydrodynamic Lubrication (EHD)

A preliminary investigation into the possible role of glass transition and glassy state behavior of lubricants in EHD contacts is reported. Measurements of the glass transition of lubricants as a function of pressure by two methods are presented along with a discussion indicating possible implications of the results to EHD lubrication.