Improving mitral valve coaptation with adjustable rings: outcomes from a European multicentre feasibility study with a new-generation adjustable annuloplasty ring system.

OBJECTIVES: To evaluate the performance and safety of an adjustable semi-rigid annuloplasty ring for mitral regurgitation (MR) in a multicentre study. METHODS: Between March 2010 and December 2011, 30 subjects underwent mitral valve (MV) repair using the Cardinal adjustable annuloplasty ring. This device is a semi-rigid ring allowing postimplantation size adjustment, under beating-heart conditions, to optimize leaflet coaptation under echocardiographic guidance. Coaptation length was determined before and after adjustment by transoesophageal echocardiography. RESULTS: The study enrolled 21 (70%) male and 9 (30%) female subjects with a mean age of 64 years. The approach was conventional midline sternotomy or mini-invasive right thoracotomy. Leaflet resection was done in 17 subjects, and chordal repair was used in 13. Concomitant procedures included coronary artery bypass grafting in 2 (7%) subjects, atrial ablation in 4 (13%) and tricuspid repair in 4 (13%). There was 1 (3%) early death unrelated to the study device. Intraoperative ring adjustment was performed in 24 of the 30 subjects. Residual MR was detected prior to adjustment in 6 subjects (4 mild and 2 moderate MR). Following adjustment, 5 subjects had no MR and 1 had trace MR. After adjustment, mean coaptation length improved from 7 ± 3 to 10 ± 3 mm (P < 0.0001). All patients who completed 1-year follow-up had less-than-mild MR, with the exception of 1 patient with ring dehiscence (and resultant 2+ MR) and 1 functional MR patient who developed recurrent 2+ MR due to persistent leaflet tethering. CONCLUSIONS: MV repair with the Cardinal adjustable annuloplasty ring is a reliable technique that enables the adjustment of the ring diameter on a beating heart under echocardiographic control. Such technology allows the optimization of leaflet coaptation, providing minimal residual MR and durable repair.

Mycophenolic acid interaction with cyclosporine and tacrolimus in vitro and in vivo: evaluation of additive effects on rat blood lymphocyte function.

The effect of mycophenolic acid (MPA) in combination with either cyclosporine (CsA) or tacrolimus (TRL) on whole-blood lymphocyte function was assessed in vitro as well as in vivo. For the in vitro studies, rat whole blood was incubated with different concentrations of MPA together with CsA or TRL. In vivo, rats (n = 6 per group) were orally treated with 2.5 or 5 mg/kg of mycophenolate mofetil (MMF), either alone or in combination with 5 mg/kg CsA or 4 mg/kg TRL. Blood was obtained before and at different times after dosing. For both in vitro and in vivo studies, mitogen-stimulated whole blood was analyzed by flow cytometry to determine inhibition of expression of lymphocyte proliferation (proliferating cell nuclear antigen, PCNA) and T-cell activation (eg, CD25). Plasma MPA concentrations were measured by HPLC, and whole-blood CsA and TRL concentrations were quantified using LC-MS/MS. In vitro, low concentrations of 250 and 500 nM MPA acted additively with CsA and overadditively with TRL to suppress lymphocyte function, whereas higher MPA concentrations (1000 nM) in these combinations did not further increase inhibition compared with monotherapy with CsA or TRL alone. In vivo, the MPA AUC0-24 showed a dose-dependent increase. CsA and TRL AUC0-24 were not influenced by the MMF dose. Combination therapy increased inhibition of lymphocyte function compared with MMF monotherapy with a pronounced effect on PCNA compared with CD25. Significant differences between 2.5 and 5 mg/kg MMF in the combination groups were observed at 2 or 6 hours after dosing because of the maximal inhibitory effect on PCNA and CD25 expression (P < 0.05, ANOVA). However, in combination with TRL no different effects on the inhibition of CD25 expression were found between the 2 MMF doses. These novel data indicate that measurement of pharmacodynamic parameters of lymphocyte function in whole blood may help to monitor drug combination therapy and provide a rationale for drug reduction to minimize toxicity without compromising efficacy.

Assessment of immunosuppressive drug interactions: inhibition of lymphocyte function in peripheral human blood.

Cyclosporin (CsA) or tacrolimus (TRL) is routinely combined with either sirolimus (SRL) or mycophenolate mofetil (MMF) in immunosuppressive regimes in organ transplantation. The aim of our study was to establish a specific human blood assay of lymphocyte function in order to assess interactions of these drug combinations. Different concentrations (10(6)-10(9) nM) of CsA, TRL, SRL or mycophenolic acid (MPA, the active metabolite of MMF) was added to whole blood of five human volunteers. Drug combinations were studied by adding 250, 500 or 1000 nM of MPA to different concentrations of CsA, TRL, or SRL or by adding 1, 10 or 25 nM of SRL to different concentrations of CsA or TRL. After concanavalin-A stimulation, whole blood cultures were analyzed by flow cytometry detecting lymphocyte proliferation and activation by bivariate expression of proliferating cell nuclear antigen (PCNA)/DNA content and T cell-surface activation antigens (e.g. CD25, CD95, and CD154). We found an order of potency inhibiting lymphocyte function with SRL>TRL>CsA>MPA. In addition, we observed enhanced inhibition of PCNA, CD25, CD95 or CD154, if either CsA or TRL was combined with low concentrations of MPA, or SRL alone or if SRL was combined with low concentrations of MPA. Data analysis revealed an independent functional synergism or partial agonism in most combinations. This human blood assay is able to assess lymphocyte function and to monitor immunosuppressive therapy. The assay also permits pharmacological analysis of drug interactions, which will lead to improved safety and therapeutic efficacy in transplanted patients.