Tetsuro Miyata

A Retrospective Study of Intravascular Ultrasound use in Patients Undergoing Endovascular Aneurysm Repair: Its Usefulness and a Description of the Procedure

OBJECTIVES To verify the usefulness and limitation of intravascular ultrasound (IVUS) in endovascular aneurysm repair (EVAR). METHODS A total of 112 consecutive patients, who underwent EVAR to treat abdominal aortic aneurysms, were examined retrospectively. Of these, 33 patients were assigned to the IVUS group because of renal failure, a suspected allergy to contrast agents or anatomical difficulties; the remaining 79 patients were assigned to the non-IVUS group. RESULTS Patients in the IVUS group required fewer intra-arterial contrast agents (IACAs) than those in the non-IVUS group (67±34ml vs. 123±50ml; p<0.01). Blood loss and operation time were comparable between the two groups. No patients died within 30 days of the operation. Three major renal complications occurred in the non-IVUS group. Renal deterioration evaluated by chronic kidney disease (CKD) stage was found to a greater extent in the non-IVUS group. CONCLUSIONS IVUS is a powerful auxiliary method in EVAR for reducing the required volume of contrast agents. The combination of IVUS and IACA usage showed good overall performance; thus, we propose the routine use of IVUS in EVAR procedures.

Predictors of mortality after emergency or elective repair of abdominal aortic aneurysm in a Japanese population

In Japan, there has been virtually no study in a population large enough to definitively demonstrate a relationship between the preoperative clinical features and postoperative outcomes in patients undergoing abdominal aortic aneurysm (AAA) repair. The aim of this study was to determine the preoperative variables that significantly predict postoperative mortality after emergency or elective repair in Japanese patients with infrarenal AAA. In this retrospective cohort study, we assessed significant predictors of postoperative mortality in 1055 consecutive patients undergoing emergency (n = 186) or elective repair (n = 869) of an infrarenal AAA at the University of Tokyo Hospital or Sakakibara Heart Institute (Tokyo, Japan). Using logistic regression analysis, anemia (hemoglobin <9 g/dl), shock (systolic blood pressure <80 mmHg), and hypocholesterolemia (total cholesterol <120 mg/dl) were found to be independent preoperative predictors of 30-day mortality after emergency repair for ruptured AAA. The hazard ratio (HR) (95 % confidence interval) for these three predictors was 5.96 (1.70–20.84), 8.48 (1.47–49.02), and 7.31 (1.96–27.35), respectively. In the elective repair cases, no significant preoperative predictor of postoperative mortality could be identified either within or beyond 30 days of surgery. Hypocholesterolemia, anemia, and shock were found to be independent preoperative predictors of a postoperative high mortality rate in Japanese patients undergoing emergency repair for ruptured infrarenal AAA.

Inverse association between the existence of coronary artery disease and progression of abdominal aortic aneurysm.

OBJECTIVES A strong degree of co-existence between coronary artery disease (CAD) and abdominal aortic aneurysm (AAA) is widely acknowledged, however, it remains to be elucidated whether the existence of CAD is associated with an accelerated expansion rate of AAA. Also, the relationship between preoperative CAD and postoperative major adverse cardiovascular events (MACE) has not been examined in Japanese patients. The aim of this study was to investigate the deleterious effects of CAD on the progression of AAA and the onset of postoperative MACE after elective AAA repair. METHODS AND RESULTS A retrospective cohort study of 665 consecutive Japanese patients who underwent elective surgical repair for infrarenal AAA at 2 high-volume Tokyo hospitals from 2003 through 2010 was performed. Preoperative CAD was shown to be a significant determinant of postoperative MACE (HR 2.29; 95%CI, 1.12-4.66; p=0.02). In the analysis of 510 patients for whom there were at least 2 follow-up CT scans of the size of their AAA before repair, the existence of CAD was shown to be inversely associated with the accelerated expansion rate of AAA. CONCLUSION This study on the patients undergone elective repair for infrarenal AAA identified an inverse association between the existence of CAD and progression of AAA as well as the significant impact of preoperative CAD on the occurrence of postoperative MACE after elective AAA repair.

A calcium-cross-linked hydrogel based on alginate-modified atelocollagen functions as a scaffold material.

We have developed a scaffold material consisting of a covalently-bonded structure of alginate and atelocollagen (AtCol). Addition of calcium ions caused the material to form a hydrogel (alginate-modified AtCol gel). The condition of the alginate-modified AtCol gel could be controlled by the feed ratio of alginate and the activating reagent. Measurement of temporal stability in culture medium suggested that covalent bonding between alginate and AtCol might contribute to the structural stability of the alginate-modified AtCol gel. Culture with endothelial cells indicated that cell adhesiveness on the alginate-modified AtCol gel was similar to that on native collagen. Collagenase digestion revealed that the alginate-modified AtCol gel had considerable ability to retain basic fibroblast growth factor. Additionally, active cell migration into alginate-modified AtCol was detected by in vitro assay using endothelial cells. These findings indicate that this gel material can be expected to function as a scaffold for inducing vascular in-growth.

Enhanced Neovascular Formation in a Novel Hydrogel Matrix Consisting of Citric Acid and Collagen

BACKGROUND Three-dimensional regenerative tissue with large bulk generally requires blood perfusion through a vascular network to maintain its viability, and one promising approach is induction of neovascular growth from the recipient bed into the tissue. To induce ingrowth of a vascular network, it is necessary to furnish the regenerative tissue with a scaffold structure for neovasculature and a delivery system for an angiogenic growth factor. As such a scaffold structure, the present study created novel hydrogel materials by chemically cross-linking alkali-treated collagen (AlCol) with trisuccinimidyl citrate (TSC). MATERIALS AND METHODS Many prototypes, consisting of several concentrations of TSC and AlCol, were implanted into the subfascial space of the rat rectus muscle, and 7 days later, the implanted materials were excised for histological analysis. Cross-sections were stained and neovascular development in the materials was evaluated by measuring vessel density, length and number of joints and branches. RESULTS Significant ingrowth of vascularized granulation was observed in some materials, which surpassed the angiogenic ability of Matrigel(TM). Further, combination with basic fibroblast growth factor (bFGF) significantly increased the vascular formation in these gels. CONCLUSIONS The TSC-AlCol gel functioned as a favorable scaffold for neovascular formation and also as a reservoir for controlled delivery of bFGF.