Shigeki Yanagi

Sustained release of vancomycin from a new biodegradable glue to prevent methicillin-resistant Staphylococcus aureus graft infection

Prosthetic graft infection with methicillin-resistant Staphylococcus aureus (MRSA) is one of the most serious complications of cardiovascular surgery. Seeking to prevent graft infection, we evaluated the efficacy of a new biodegradable hydrogel glue (new-glue) composed of aldehyded dextran and epsilon-poly(L-lysine) which acts as a local sustained-release carrier of vancomycin. Rats (n=40) were implanted with 1-cm(2) Dacron grafts in the subcutaneous pockets. Groups (n=10 each) were as follows: no treatment (group A), topical vancomycin solution (group B), new-glue without vancomycin (group C) or new-glue containing 1 mg of vancomycin (group D). Twenty-four h after the implantation, 2.0x10(7) colony-forming units of MRSA was inoculated onto the graft surface. Seven days thereafter, the graft was sampled and cultured. The quantity of MRSA was significantly lower in group D than in the other groups (P<0.0001). About 95% of the total vancomycin was released from the new-glue over the 72 h experimental period, and the tissue concentration of vancomycin remained above the minimum inhibitory concentration for the MRSA strain throughout the experiment. This new vancomycin-containing glue effectively prevented prosthetic graft infection and thus may be a promising biodegradable drug vehicle.

Twenty-Year Outcome of Aortic Valve Replacement With St. Jude Medical Mechanical Valves in Japanese Patients

BACKGROUND Bioprostheses have become increasingly popular for aortic valve replacement (AVR) in recent years, but mechanical valves are still the standard choice, especially for younger patients. The aim of this study was to assess the very long-term outcomes in Japanese patients who underwent AVR with St. Jude Medical (SJM) mechanical valves. METHODSANDRESULTS From 1991 to 2001, a total of 816 patients underwent AVR with SJM mechanical valves in 5 hospitals. Of these, 801 patients (mean age, 58.3±11.7 years) were analyzed in this study. There were 24 in-hospital deaths (3.0%). Mean follow-up duration was 11.6±6.7 years and the 10-year follow-up rate was 84.1%. Freedom from valve-related death at 5, 10, 15, and 20 years was 96.2%, 92.7%, 88.8%, and 86.6%, respectively. The linearized ratio of major bleeding events and thromboembolic events was 1.1% per patient-year and 1.0% per patient-year, respectively. Freedom from reoperation for the aortic prosthesis was 98.0% and 94.8% at 10 and 20 years, respectively. CONCLUSIONS The SJM mechanical valve provided excellent long-term freedom from valve-related death and reoperation in patients undergoing AVR. Therefore, this valve should be recommended to younger patients who wish to avoid reoperation.

Comparison of the Long-Term Outcomes of Mechanical and Bioprosthetic Aortic Valves ― A Propensity Score Analysis ―

BACKGROUND The aim of this study was to assess the long-term outcomes of aortic valve replacement (AVR) with either mechanical or bioprosthetic valves according to age at operation.Methods and Results:A total of 1,002 patients (527 mechanical valves and 475 bioprosthetic valves) undergoing first-time AVR were categorized according to age at operation: group Y, age <60 years; group M, age 60-69 years; and group O, age ≥70 years). Outcomes were compared on propensity score analysis (adjusted for 28 variables). Hazard ratio (HR) was calculated using the Cox regression model with adjustment for propensity score with bioprosthetic valve as a reference (HR=1). There were no significant differences in overall mortality between mechanical and bioprosthetic valves for all age groups. Valve-related mortality was significantly higher for mechanical valves in group O (HR, 2.53; P=0.02). Reoperation rate was significantly lower for mechanical valves in group Y (HR, 0.16; P<0.01) and group M (no events for mechanical valves). Although the rate of thromboembolic events was higher in mechanical valves in group Y (no events for tissue valves) and group M (HR, 9.05; P=0.03), there were no significant differences in bleeding events between all age groups. CONCLUSIONS The type of prosthetic valve used in AVR does not significantly influence overall mortality.