Yu Shomura

Silicone-coated polypropylene hollow-fiber oxygenator : Experimental evaluation and preliminary clinical use

BACKGROUND A membrane oxygenator consisting of a microporous polypropylene hollow fiber with a 0.2-microm ultrathin silicone layer (cyclosiloxane) was developed. Animal experimental and preliminary clinical studies evaluated its reliability in bypass procedures. METHODS Five 24-hour venoarterial bypass periods were conducted on dogs using the oxygenator (group A). In 5 controls, bypass periods were conducted using the same oxygenator without silicone coating (group B). As a preliminary clinical study, 14 patients underwent cardiopulmonary bypass with the silicone-coated oxygenator. RESULTS Eight to 16 hours (mean, 12.2 hours) after initiation of bypass, plasma leakage occurred in all group B animals, but none in group A. The O2 and CO2 transfer rates after 24 hours in group A were significantly higher than at termination of bypass in group B (p < 0.005 and p < 0.03, respectively). Scanning electron microscopy of silicone-coated fibers after 24 hours of bypass revealed no damage to the silicone coating of the polypropylene hollow fibers. In the clinical study, the oxygenator showed good gas transfer, acceptable pressure loss, low hemolysis, and good durability. CONCLUSIONS This oxygenator is more durable and offers greater gas transfer capabilities than the previous generation of oxygenators.

Late Results of Mitral Valve Repair With Glutaraldehyde-Treated Autologous Pericardium

BACKGROUND Mitral valve repair is an established surgical procedure for treating severe organic mitral regurgitation. The mechanisms of mitral regurgitation due to infective endocarditis include rheumatic disease and congenital diseases such as a lack of leaflet tissue, and thus additional material is required to create a functional coaptation surface. We review our experience with 139 patients who underwent mitral valve repair with glutaraldehyde-treated autologous pericardium to treat organic mitral regurgitation between March 1992 and November 2011. METHODS Mitral valve disease mainly consisted of infective endocarditis in 51 patients (active, n = 32; healed, n = 19) and rheumatic disease in 47. This procedure was also applied to 12 patients who required reoperation after mitral valve repair for degenerative, congenital, or rheumatic mitral regurgitation. The mean follow-up was 4.5 ± 4.3 years (maximum 19.1). RESULTS Actuarial survival at 10 years was 84% ± 5%. Eleven reoperations proceeded at a mean of 68 months after surgery. The causes of reoperation were rheumatic disease progression (n = 4), infection (n = 3), patch dehiscence (n = 2), progressive fibrosis of the remaining mitral valve tissue after infective endocarditis (n = 1), and patch tear (n = 1). Mitral valves were replaced in 8 patients and re-repaired in 3 patients. The autologous pericardium was not calcified at the time of reoperation. The rate of freedom from reoperation was 82% ± 7% at 10 years. CONCLUSIONS Mitral valves that might otherwise require replacement can be durably and predictably repaired using glutaraldehyde-treated autologous pericardium.

Dissecting Aneurysm of the Superior Mesenteric Artery Successfully Treated by Endovascular Stent-Graft Placement

AbstractSpontaneous and isolated dissecting aneurysm of the superior mesenteric artery is a rare event that has been successfully treated by surgery in several reported cases. To our knowledge, we present the first case of a patient with spontaneous and isolated dissecting aneurysm of the superior mesenteric artery that was successfully treated by endovascular stent-graft placement.

Outcomes of mitral valve repair for bileaflet prolapse

OBJECTIVE Repair of bileaflet prolapse has been considered to be technically demanding and challenging. To assess the reliability and durability of mitral valve repair for bileaflet prolapse, the present study compared the outcomes of mitral valve repair for bileaflet prolapse with those for posterior prolapse. METHODS From January 1991 to April 2010, 191 consecutive patients with bileaflet prolapse (group B) underwent mitral valve repair using a combination procedure of expanded polytetrafluoroethylene chordal reconstruction for anterior prolapse, resection suture technique with/without sliding technique for posterior prolapse, and ring annuloplasty. During the same period, 323 patients with posterior prolapse (group P) underwent standard mitral valve repair. Serial echocardiograms were obtained at discharge and 1, 3, 5, and 10 years postoperatively. RESULTS The mean age in group B (54 ± 15 years) was significantly younger than that in group P (61 ± 12 years). Survival, including hospital death at 10 years, was superior in group B (group B, 90% ± 3%; group P, 83% ± 3%; P = .046). At 10 years, no significant differences were found between the groups in terms of freedom from recurrent mitral regurgitation of more than mild (group B, 89% ± 3%; group P, 90% ± 2%), freedom from reoperation (group B, 97% ± 2%; group P, 97% ± 1%), and event-free survival (group B, 79% ± 5%; group P, 83% ± 3%). CONCLUSIONS The reproducibility and reliability of mitral valve repair for bileaflet prolapse compares favorably with that of posterior leaflet prolapse. Early surgery might be recommended for patients with severe mitral regurgitation owing to bileaflet prolapse.

Clinical Outcomes of Redo Valvular Operations: A 20-Year Experience

BACKGROUND A higher operative mortality rate has been reported after redo valvular procedures than after the primary operation. METHODS Outcomes of 330 consecutive patients undergoing 433 redo valvular operations at our institute during a 20-year period (January 1990 to December 2010) were reviewed retrospectively. The mean follow-up was 6.4 years (range, 0.05 to 1.3 years). Logistic regression analysis was used to identify factors associated with hospital death. RESULTS The overall hospital mortality rate was 6.7% (29 of 433 procedures). Logistic regression analysis identified only advanced New York Heart Association (NYHA) class as an independent predictor of hospital death. Overall survival at 5, 10, and 15 years was 83.6%±2.2%, 70.7%±3.4%, and 61.5%±4.5%, respectively. The 5-, 10-, and 15-year survivals for the first redo vs more than second redo groups were 86.5%±2.4% vs 74.7%±5.5%, 71.8%±3.9% vs 66.8%±6.6%, and 60.2%±5.7% vs 63.1%±7.2%, respectively (log-rank P=0.505). The 5- and 10-year survivals for NYHA class I/II vs III/IV patients were 91.5%±2.1% vs 70.4%±4.5% and 77.8%±4.1% vs 58.5%±5.6%, respectively (log-rank p<0.005). CONCLUSIONS Redo valvular operation in NYHA class III/IV patients is associated with high hospital death and poor long-term survival. To achieve low hospital death and good long-term survival, redo operations, including more than third redo operations, should be performed in patients with lower NYHA class.

Successful Treatment for Infected Aortic Aneurysm Using Endovascular Aneurysm Repairs as a Bridge to Delayed Open Surgery

Management of infected aortic aneurysms, which can be life-threatening, remains challenging. Open surgical treatments, including debridement of the infected aorta and the surrounding tissue and either in situ reconstruction or extra-anatomic bypass covering with omentum or muscle flap, are the mainstay of therapy. However, increasing advances in technology have made endovascular treatment of infected aneurysms feasible. The present study describes the first clinical report of successful treatment of an infected aneurysm using endovascular techniques in the acute phase, followed by delayed open surgery.

Clinical outcomes of open heart surgery in patients with atopic dermatitis

Atopic dermatitis is a skin condition often complicated by colonization with Staphylococcus aureus, which increases the risk of infective endocarditis, skin cellulitis and osteomyelitis. Positive cultures for Staphylococcus aureus are obtained from 70% to 80% of wounds in patients with mediastinitis. Thus sternotomy carries increased risk of mediastinitis in patients with atopic dermatitis. We retrospectively reviewed 25 patients with atopic dermatitis who underwent cardiac surgery via a median sternotomy or thoracotomy from January 1997 to September 2010 at our institution. Postoperative mediastinitis due to methicillin-resistant Staphylococcus aureus was found in 3 patients who had a median sternotomy. They were ultimately discharged in good condition. No mediastinitis occurred in patients undergoing thoracotomy. Mediastinitis may occur due to direct exposure of the bone marrow to methicillin-resistant Staphylococcus aureus in patients with atopic dermatitis whose skin is colonized with such bacteria. Thoracotomy may be a better surgical approach in patients with atopic dermatitis who require thoracic surgery.

Clinical evaluation of a silicone coated hollow fiber oxygenator.

In this article, the clinical experience with a cardiopulmonary bypass (CPB) using a newly developed hollow fiber oxygenator with an ultra-thin layer of silicone is reported. A comparative study of biocompatibility between the new oxygenator and a heparin coated oxygenator is also described. The CPB was performed with a silicone coated oxygenator, Mera Excelung Binding Prim HPO 15 H-C (Group I, n = 6) or Binding Prim HPO 25 H-C (Group II, n = 10) (Senko Medical Instrument Mfg., Tokyo, Japan). Air could be vented through the silicone coated hollow fibers, and it was easy to prime the circuits. The CPB duration was 101 ± 37 min and 170 ± 64 min for Groups I and II, respectively. There were no deaths and no complications from CPB. Partial arterial pressure of O2 levels 60 minutes after the start of CPB were 529 ± 28 mm Hg and 529 ± 28 mmHg for Group I and II, respectively. of Co. levels 60 min after the start

Clinical Experience with the Nikkiso Centrifugal Pump

The Nikkiso HPM-15 is a minimally sized centrifugal pump. Preliminary results regarding clinical use of this pump for cardiopulmonary bypass (CPB) procedures have been reported previously. Recently, we have managed some additional cases using a newly developed controller. This article reports our clinical experiences with the use of this pump. We have managed 23 cases with a Nikkiso centrifugal pump. Twenty-two patients underwent CPB and 1 patient with fulminant viral myocarditis underwent percutaneous cardiopulmonary support (PCPS). With this pump, the circuit was extremely easy to prepare and deaeration was achieved readily. Hemodynamics during CPB and PCPS were stable in all cases. The increase in serum-free hemoglobin levels during CPB with this pump was as low as that seen in preliminary tests. A decrease in the platelet count was observed after the initiation of CPB with this pump; however, platelet counts returned to preoperative values 7 days after surgery. Moreover, urine output during CPB with this pump was as high as that seen in preliminary tests. No abnormalities in renal or liver function occurred during CPB. It appears that this new centrifugal pump is safe and easy to operate, and we conclude that it is useful for CPB and PCPS.

Physiology of Nonpulsatile Circulation

Investigation of the pathophysiology of nonpulsatile circulation began many years ago, but the majority of the research to date has dealt with the acute period of extracorporeal circulation. With the development of nonpulsatile pumps for long-term use, it is thought that the study of the physiological reaction to this long-term use will proceed, and it is believed that the time for a reevaluation of this pathophysiology has come. In the future, with the development of pumps capable of long-term safe operation, the pathophysiology of nonpulsatile circulation will become better understood, and it will become known whether a pulsatile artificial heart will be effective.