Shinichi Mizutani

Determination of the Degree of Acetylation of Chitin/Chitosan by Pyrolysis-Gas Chromatography in the Presence of Oxalic Acid

A new method to determine directly and rapidly the degree of acetylation of chitin/chitosan was developed based on reactive pyrolysis-gas chromatography in the presence of an oxalic acid aqueous solution. The degree of acetylation was precisely evaluated on the basis of peak intensities of the characteristic products such as acetonitrile, acetic acid, and acetamide originating from the N-acetyl group of N-acetyl-d-glucosamine units of chitin/chitosan. The observed values were in good agreement with those obtained by (1)H NMR and the other methods. Moreover, the proposed technique was applicable to any kinds of chitin/chitosan samples over the whole range of acetylation including insoluble chitin/chitosan and perfectly acetylated artificial chitin having higher crystallinity to which (1)H NMR had been inapplicable.

Repetitive atrial flutter as a complication of the left-sided simple maze procedure

BACKGROUND Of 41 patients who had undergone a left-sided simple maze procedure, 4 (9.8%) developed repetitive tachycardia due to atrial flutter, and required radiofrequency catheter ablation. Linear ablation of the right atrial isthmus was effective to treat atrial flutter. METHODS We conducted an electrophysiologic study of atrial flutter and determined its reentry circuit on the atrium. We consider how to reduce atrial flutter after the left-sided simple maze procedure. RESULTS Common atrial flutter through the right atrial isthmus was induced in all 4 patients, and linear ablation on the right atrial isthmus was effective in 3 of these. An incisional atrial flutter around the right atriotomy was also induced in 2 of 4 patients; both were successfully treated by linear ablation between the right atriotomy and the inferior vena cava. CONCLUSIONS Common atrial flutter through the right atrial isthmus is a risk after the left-sided simple maze procedure. When a left-sided simple maze procedure is performed, sufficient cryoablation on the right atrial isthmus of the arrested heart should be administered to prevent postoperative atrial flutter.

Synthesis of a novel N‐selective ester functionalized chitin derivative and water‐soluble carboxyethylchitin

A novel chitin detivative having a pendant ester function, 2-N-(2-ethoxycarbonylmethyl)chain (2), was synthesized by a Michael-type nucleophilic addition of an amino group of partially deacetylated chitin (1) to ethyl acrylate in phosphate buffer/methanol (5:3, v/v) at 40°C. N-Selective monosubstitution occurred exclusively in the polymer reaction, which was supported by a reaction of methyl 2-ammo-2-deoxy-D-glucopycanoside with ethyl acrylate to afford methyl 2-N-(2-ethexycarbonylethyl)-2-amino-2-deoxy-D-glucopyranoside. The degrees of substitution (DSs) of 2 were determined by 1 H NMR spectroscopy. T1 analysis of 2 was carried out in other to clarify differences of signal intensities of the pendant ester protons and the pyranose ring pronons. The result of the T 1 measurement suggested a relatively restricted molecular motion of the chitin backbone in comparison with the flexible pendant ethyl ester groups. Furthermore, 2-N-(2-carboxyethyl)chitin sodium salt (3) was synthesized from ethyl aorylate and 1 by the Michael addition followed by hydrolysis in 0,1 N NaOH aq, as 40°C, The DSs of 3 were varied from 0.26 to 0.88, which were almost controlled by the reaction period of the Michael reaction from 6 to 168 h. 3 showed good solubility in water. Viscosity measured on a cone-plate viscometer for the 1.0 wt.-% aqueous solution of 3 (DS, 0,26) was 0.074 Pas.sec.

Implementation of bundled interventions greatly decreases deep sternal wound infection following cardiovascular surgery

OBJECTIVE Surgical site infection (SSI), particularly deep sternal wound infection (DSWI), is a serious complication after cardiovascular surgery because of its high mortality rate. We evaluated the effectiveness of an SSI bundle to reduce DSWI and identify the risk factors for DSWI. METHODS During the period January 2004 to February 2012, 1374 consecutive patients undergoing cardiovascular surgery via sternotomy were included. The cohort was separated into periods from January 2004 through February 2007 (period I, 682 patients) and March 2007 through February 2012 (period II, 692 patients). During period II, all preventive measures for DSWI were completed as an SSI bundle. We compared the DSWI rate between the 2 periods. Univariate and multivariate analyses were performed for the entire period to identify the risk factors for DSWI. RESULTS DSWI occurred in 13 patients (1.9%) during period I and in 1 patient (0.14%) during period II. The DSWI rate during period II was significantly decreased by 93%, compared with period I (P=.001). Independent risk factors for DSWI included obesity (odds ratio [OR], 3.4; 95% confidence interval [CI], 1.00-11.75; P=.049), the use of 4 sternal wires (OR, 8.2; 95% CI, 1.39-48.14; P=.020), long operative time (OR, 4.4; 95% CI, 1.20-16.23; P=.026), and postoperative renal failure (OR, 9.0; 95% CI, 2.44-33.30; P=.001). CONCLUSIONS Complete implementation of simple multidisciplinary prevention measures as a bundle can greatly decrease the incidence of DSWI.

Retrograde Cardioplegia Revisited: Open Technique for Long Aortic Cross Clamping

BACKGROUND The efficacy of retrograde cardioplegia for myocardial protection is still controversial. In our institution, we exclusively use intermittent administration of tepid, undiluted blood supplemented with potassium and magnesium for the cases with aortic insufficiency, requiring aortotomy, or undergoing mitral valve repair. In using this retrograde technique, we make a point of cannulating a retrograde perfusion catheter under direct vision following right atriotomy. The purpose of this retrospective study is to evaluate the clinical outcome of using this technique. METHODS This study comprises 49 patients who underwent elective valve surgery using direct-vision retrograde cardioplegia exclusively, requiring more than 3h aortic cross-clamping. Their clinical outcome was reviewed retrospectively. RESULTS There was no hospital mortality in this study. No patient was noted to have evidence of mediastinitis, myocardial infarction, or cerebral complications in the postoperative period. The case requiring the longest aortic cross-clamping time (380 min) survived the operation without the use of intra-aortic balloon pumping or percutaneous cardiopulmonary support, and the postoperative course was uneventful. CONCLUSIONS Our result suggests that direct-vision retrograde cardioplegia is a safe and effective method of cardioplegia delivery, and provides a longer period of myocardial protection than previously thought.

Determination of degree of substitution in N-carboxyethylated chitin derivatives by pyrolysis-gas chromatography in the presence of oxalic acid

Abstract Reactive pyrolysis-gas chromatography (Py-GC) in the presence of oxalic acid was applied to the determination of degree of substitution (DS) in N -carboxyethylated chitin derivatives. On the obtained pyrogram, characteristic products, such as methylacrylate, ethylacrylate and acrylic acid originating from the carboxyethyl branches of the chitin derivatives, were clearly observed together with those from the N -acetyl- d -glucosamine units, such as acetonitrile, acetic acid and acetamide. On the basis of relative yields of these characteristic products, the DS values were precisely evaluated. The results by reactive Py-GC also supported the validity of the results obtained by 1 H NMR that the mono-alkylation onto the amino group of the original chitin was favorable for the derivatization of the samples.

Management of intraoperative aortic dissection with a direct cannulation on the intimal flap.

We report a case of severe aortic stenosis in which intraoperative aortic dissection developed from aortic cross-clamp. The patient showed symptoms of malperfusion, but was successfully managed by direct inflow cannulation on the intimal flap into the true lumen. She then recovered well without further incident.

The value of caval division in the maze procedure with valve surgery.

Operative predictors for successful elimination of atrial fibrillation (AF) following the maze procedure are not yet known. We have often divided the superior vena cava (SVC) during the maze procedure, not to eliminate AF but in order to explore the mitral valve. However, in multivariate analysis of 79 patients, the division of SVC, as well as the duration of AF, was found to be the strongest predictor of AF elimination. The explanation of this observation is not clear, but denervation of the cardiac autonomic nervous system or the existence of paroxysmal AF originating from the SVC could be involved.

Saphenous Vein Graft Aneurysm Repaired with Radial Artery Graft Pre-Sewn Vascular Prosthesis Patch.

Saphenous vein graft aneurysms are rare but are potentially fatal and their optimal management is not clearly established. Herein, we report a case of a saphenous vein graft aneurysm that was successfully treated with surgical intervention, including aneurysmal resection and re-grafting. The aneurysm, detected 36 years after coronary artery bypass grafting, was located at the proximal part of the saphenous vein graft to the posterolateral branch; the flow of the left anterior descending coronary artery was limited due to compression of the left internal thoracic artery by the adjacent aneurysm. The proximal anastomotic site was reconstructed under deep hypothermic circulatory arrest using a radial artery graft pre-sewn vascular prosthesis patch.

Pathogenesis of paravalvular leakage as a complication occurring in the late phase after surgery

Paravalvular leakage (PVL) remains an unavoidable late complication after valve surgery. We indicate surgery only cases with progressive congestive heart failure and/or hemolytic anemia. We review our clinical experiences of PVL surgery. Between 1992 and 2009 we experienced 8 cases of aortic PVL—6 subjects after primary aortic valve replacement (AVR) and 2 subjects after re-AVR—and 10 subjects with mitral PVL—5 cases after primary mitral valve replacement (MVR) and 5 cases after re-MVR. Mitral PVL began in the later phases after surgery and had more severe symptoms, because of heart failure and/or hemolytic anemia, than aortic PVL. Aortic PVL occurred more frequently because of laxation of sutured threads without frequent sites. Conversely, mitral PVL was mainly caused by cutting annulus tissue around the anterior commisurae after primary MVR, and by a valve-on-valve structure on the middle scallop of the posterior leaflet or circumferentially after re-MVR. All operations were performed safely and all patients were discharged uneventfully. No cases experienced recurrence of PVL in the follow-up period. The symptoms of PVL became exacerbated, and our surgical indications based on these symptoms were validated. Valve-on-valve replacement, which was a major cause of PVL after re-MVR, should be avoided in a re-MVR procedure. Cautious follow-up is necessary, even in the late phase after surgery, especially for patients who have undergone MVR.