Mid-term outcomes of surgical aortic valve replacement using a mosaic porcine bioprosthesis with concomitant mitral valve repair.

This study retrospectively evaluated the mid-term outcomes of surgical aortic valve replacement (SAVR) using a stented porcine aortic valve bioprosthesis (Mosaic; Medtronic Inc., Minneapolis, MN, USA) with concomitant mitral valve (MV) repair. From 1999 to 2014, 157 patients (median [interquartile range] age, 75 [70-79] years; 47% women) underwent SAVR with concomitant MV repair (SAVR + MV repair), and 1045 patients (median [interquartile range] age, 76 [70-80] years; 54% women) underwent SAVR only at 10 centers in Japan as part of the long-term multicenter Japan Mosaic valve (J-MOVE) study. The 5-year overall survival rate was 81.5% ± 4.1% in the SAVR + MV repair group and 85.1% ± 1.4% in the SAVR only group, and the 8-year overall survival rates were 75.2% ± 5.7% and 78.1% ± 2.1%, respectively. Cox proportional hazards analysis showed no significant difference in the survival rates between the two groups (hazard ratio, 0.87; 95% confidence interval, 0.54-1.40; P = 0.576). Among women with mild or moderate mitral regurgitation who were not receiving dialysis, those who underwent SAVR + MV repair, were aged > 75 years, and had a preoperative left ventricular ejection fraction of 30-75% tended to have a lower mortality risk. In conclusion, this subgroup analysis of the J-MOVE cohort showed relevant mid-term outcomes after SAVR + MV repair.

[Repair of Traumatic Brachiocephalic Artery Pseudoaneurysm by Open Surgery:Report of a Case].

The patient is a 56-year-old man. He fell while playing golf and sustained a contusion on his right chest. He fell into hemorrhagic shock during surgery for a right clavicle fracture at a nearby hospital and required cardiac resuscitation. Computed tomography( CT) scan revealed left pneumothorax and right hemothorax, and a contrast-enhanced CT scan revealed a pseudoaneurysm at the brachiocephalic artery origin. He underwent surgery three weeks later. Surgery was performed through a median sternotomy and partial arch replacement (zone 2) with antegrade cerebral perfusion under moderate hypothermia. He was discharged on postoperative day 10 without significant complications.

Recommendations for the management of the vascular involvement in Behçet's disease by the Japanese National Research Committee for Behçet's disease-secondary publication.

OBJECTIVES: This study aimed to develop clinical guidelines for the management of vascular Behçet's disease (BD) by the Behçet's Disease Research Committee of the Ministry of Health, Labour and Welfare of the Japanese Government. METHODS: A task force proposed clinical questions (CQs) concerning vascular BD based on a literature search. After screening, draft recommendations were developed for each CQ and brushed up in three blinded Delphi rounds, leading to the final recommendations. RESULTS: This study provides recommendations for 17 CQs concerning diagnosis and differential diagnoses, assessment of disease activity, and treatment. The guidelines recommend immunosuppressive treatments, for both arterial and venous involvement with active inflammation. Anticoagulation is also recommended for deep vein thrombosis except in high-risk patients. Surgical and endovascular therapies can be optional, particularly in patients with urgent arterial lesions undergoing immunosuppression. In addition, two sets of algorithms for diagnosis and treatment are shown for arterial and venous involvement. CONCLUSIONS: These recommendations are expected to serve as useful tools in the daily clinical practice of BD. This content has already been published in Japanese in the Guideline for the Management of Behçet's Disease 2020 and is submitted with permission from both the primary and secondary publishers.

Virtual Reality Computed Tomography Evaluation　- Anatomy and Clinical Implications for Valve-Sparing Aortic Root Replacement.

BACKGROUND: Three-dimensional aortic root evaluation using virtual reality (VR) techniques for valve-sparing aortic root replacement (VSARR) preparation has not yet been implemented, so we demonstrated VR computed tomography (VR-CT) and assessed its utility for VSARR.Methods and Results: We enrolled 72 patients who underwent multidetector CT before elective VSARR for annuloaortic ectasia with tricuspid aortic valve. The geometries of their aortic roots were measured with a VR-CT workstation. The mean values of geometric height (GH), free margin length (FML), and commissural height (CH) were 17.2±2.4 mm, 36.0±5.2 mm, and 24.0±4.3 mm, respectively. The right coronary/noncoronary CH was significantly greater than the left coronary/right coronary and left coronary/noncoronary CH. The left coronary cusp had the shortest FML, intercommissural distances (ICD), and smallest central angle. Although the right coronary cusp had the largest values for FML, ICD, and central angle, the right coronary cusp had the lowest GH and EH. The VR-CT measurements strongly correlated with intraoperative alternatives, especially with mean GH (R2=0.75) and left coronary/noncoronary CH (R2=0.79). Furthermore, mean GH was observed to be significantly different among the selected graft size groups; therefore, the preoperative mean GH could play a significant role in graft sizing. CONCLUSIONS: VR-CT evaluation allows a thorough understanding of aortic root anatomy, which could facilitate VSAAR.

Long-Term Outcomes of the Mosaic Mitral Porcine Bioprosthesis in Japan　- Results From the Japan Mosaic Valve Long-Term Multicenter Study.

BACKGROUND: This study retrospectively evaluated the long-term patient outcomes and durability of the Mosaic mitral porcine bioprosthesis in the Japan Mosaic valve long-term multicenter study.Methods and Results:The medical records of 390 patients who underwent mitral valve replacement with the Mosaic bioprosthesis at 10 centers in Japan (1999-2014) were reviewed. Patient data were collected using the Research Electronic Data Capture software. Patient survival was determined using the Kaplan-Meier method. Freedom from structural valve deterioration (SVD) and valve-related reoperation and death were determined using actuarial methods. The median (interquartile range [IQR]) age of the cohort was 73 (69-77) years. The median (IQR) follow-up period was 4.83 (1.84-8.26) years. The longest follow-up period was 15.8 years. The 30-day mortality rate was 5.4%. The 12-year actuarial survival rate was 54.1±4.5%, and the freedom from valve-related death was 85.3±3.4%. The freedom from reoperation at 12 years was 74.3±5.7%. The freedom from SVD at 12 years was 81.4±6.6% for patients aged ≥65 years and 71.6±11.1% for those aged <65 years. The median (IQR) mean pressure gradient was 4.1 (3.0-6.0) and 5.6 (4.0-6.7) mmHg at 1 and 10 years, respectively. The median (IQR) effective orifice area was 1.7 (1.4-2.0) and 1.4 (1.2-1.6) cm2at 1 and 10 years, respectively. CONCLUSIONS: The Mosaic porcine bioprosthesis offered satisfactory long-term outcomes for up to 12 years.

Two-Year Results of the 17-mm Avalus Aortic Valve in the PERIGON Japan Trial.

BACKGROUND: The PERIcardial SurGical AOrtic Valve ReplacemeNt (PERIGON) Japan Trial was developed to assess the safety and effectiveness of the 17-mm Avalus bioprosthesis (Medtronic, Minneapolis, MN, USA) in patients undergoing surgical aortic valve replacement.Methods and Results:The primary endpoint in the trial was the percentage of patients achieving the composite of at least 1 class improvement in New York Heart Association (NYHA) functional class at 1 year compared with baseline and effective orifice area index (EOAI) of 0.6 cm2/m2or greater at 1-year after implantation, compared with a performance goal of 60%. The present study reports outcomes through 2 years. Eleven patients were implanted (10 [91%] female, median age 78.3 years). From baseline to 1 year, 10 subjects (91%) showed an improvement in NYHA classification. At 1 year, mean (±SD) EOAI was 0.82±0.17 cm2/m2, with 10 patients (91%) having an EOAI ≥0.6 cm2/m2. As such, 9 of 11 patients (82%) successfully met the primary endpoint. One death occurred between the 1- and 2-year follow-up visits, unrelated to the valve. There were no valve reinterventions, explants, or device deficiencies through 2 years. CONCLUSIONS: The PERIGON Japan Trial met its primary endpoint. Surgical implantation of the 17-mm Avalus aortic bioprosthesis can be performed with an acceptable incidence of device-related adverse events, and the valve performs effectively based on echocardiographic findings.

Treatment strategies for malperfusion syndrome secondary to acute aortic dissection.

OBJECTIVE: Presenting our experience of treating patients with organ malperfusion secondary to acute aortic dissection. PATIENTS: Among 383 patients who underwent aortic repair for acute type A aortic dissection from 1999 to 2017, 107 patients were operated on because of vascular complications. Fourteen patients had coronary, 50 had brain, 3 had paraplegia, 13 had superior mesenteric artery, 21 had lower limb, and 16 had combined organ malperfusion. Age was 65.8 years. RESULTS: In coronary malperfusion, three had a preoperative percutaneous coronary intervention, and two had mechanical support. All underwent repair of the aorta. Hospital mortality was 28.5%. Fifty patients had brain malperfusion. Hemiplegia was found in 28 patients, transient ischemic attack in 10, and coma in 12. The level of consciousness was severe in 12, moderate in 18, and mild in 20. Twenty-eight percent died of a stroke. Nine had direct perfusion from the right common carotid artery, and the consciousness level was improved in 5 patients. Eight patients had mesenteric malperfusion. Four patients had a central aorta repair first, and four patients had peripheral intervention first. Three patients had a bypass grafting to the superior mesenteric artery, and one had a catheter intervention. Postoperative mortality was found in four patients due to bowel necrosis and six required resections of the bowel. CONCLUSION: Acute organ malperfusion caused by the aortic dissection requires accurate and prompt diagnosis to proceed with an appropriate intervention before repairing the central aorta for preventing irreversible organ damage.

Long-Term Outcomes of the Mosaic Aortic Porcine Bioprosthesis in Japan　- Results From the Japan Mosaic Valve Long-Term Multicenter Study.

BACKGROUND: This study retrospectively evaluated the long-term patient outcomes and durability of the Mosaic aortic porcine bioprosthesis in the Japan Mosaic valve long-term multicenter study.Methods and Results:We reviewed the records of 1,202 patients who underwent aortic valve replacement with the Mosaic bioprosthesis at 10 centers in Japan (1999-2014). Patient data were collected using Research Electronic Data Capture. Patient survival was determined by Kaplan-Meier methodology. Freedom from structural valve deterioration (SVD) and valve-related reoperation and death were determined by actuarial methods. The median (interquartile range [IQR]) age of the cohort was 76 (70-80) years. The median (IQR) follow-up period was 3.52 (1.71-5.35) years. The longest follow-up was 15.8 years. The 30-day mortality rate was 2.3%. The 12-year actuarial survival rate was 59.9±7.5%, and the freedom from valve-related death was 81.1±7.9%. The freedom from reoperation was 86.4±2.6% at 12 years. The freedom from SVD at 12 years was 93.5±2.9% for patients aged ≥65 years and 98.2±1.8% for those aged <65 years. The median (IQR) systolic pressure gradient was 17 (12-23) and 19 (12-25) mmHg at 1 and 10 years, respectively. The median (IQR) effective orifice area was 1.2 (1.1-1.5) and 1.1 (1-1.5) cm2at 1 and 10 years, respectively. CONCLUSIONS: The Mosaic porcine bioprosthesis showed satisfactory long-term outcomes over 12 years.

Outcomes of Thoracic Aortic Surgery in Patients With Coronary Artery Disease　- Based on the Japan Adult Cardiovascular Surgery Database.

BACKGROUND: Coronary artery disease (CAD) is associated with increased morbidity and mortality after open repair of thoracic aorta. Nevertheless, the efficacy of preoperative coronary angiography (CAG) and revascularization is controversial. The aim of this study was to clarify the effect of preoperative CAD on surgical outcome by reviewing the Japan Adult Cardiovascular Database. Methods and Results: This study involved 4,596 patients who underwent open surgery for true thoracic aortic aneurysm between 2004 and 2009. After excluding patients with concomitant cardiac operation, except coronary artery bypass grafting (CABG), the remaining 1,904 patients with coronary artery stenosis included 995 cases of simultaneous CABG. The prevalence of CAD was significantly higher in patients with diabetes, renal dysfunction, hyperlipidemia, cerebrovascular disorders, peripheral artery lesions, old myocardial infarction (MI), and coronary intervention. Patients with simultaneous CABG had severe CAD compared with those without, with no other major differences in patient background noted. Thirty-day postoperative and in-hospital mortalities were higher in CAD patients. Incidence of perioperative MI was higher in patients who underwent open aortic repair with simultaneous CABG, but simultaneous CABG did not affect operative mortality. CONCLUSIONS: In patients with surgically treated true aortic aneurysm, CAD was frequently observed, suggesting that aggressive preoperative coronary evaluation is needed.

Safety of Fibrinogen Concentrate and Cryoprecipitate in Cardiovascular Surgery: Multicenter Database Study.

OBJECTIVES: To investigate whether administering fibrinogen concentrate or cryoprecipitate is associated with increased postoperative thromboembolic events and improved mortality in patients undergoing thoracic aortic surgery. DESIGN: Multicenter retrospective cohort study using propensity-score analyses and multivariate logistic regression analysis to control for confounders. SETTING: Four hospitals (1 national cardiovascular center and 3 university hospitals). PARTICIPANTS: Patients undergoing thoracic aortic surgery with cardiopulmonary bypass between January 2010 and October 2012 (n = 1,047). INTERVENTIONS: Outcomes in patients treated with fibrinogen concentrate or cryoprecipitate (fibrinogen group) were compared with those who did not receive these products (no fibrinogen group) based on propensity-score matching. Multivariate logistic regression analysis then was performed to confirm the results. MEASUREMENTS AND MAIN RESULTS: Among 1,047 patients enrolled in this study, 247 patients received fibrinogen concentrate or cryoprecipitate. The median amount of administered fibrinogen was 3 g (interquartile range 2-4 g). Eighty-seven patients were excluded from the propensity-score matching because of missing data. Propensity-score-matched analysis showed no significant difference in the incidence of thromboembolic events or 30-day mortality rate between the groups. Multivariate analysis revealed that the fibrinogen group showed no significant difference in thromboembolic events (odds ratio 1.22; 95% confidence interval 0.76-1.95; p = 0.408) or mortality rate (odds ratio 0.44; 95% confidence interval 0.18-1.12; p = 0.081) compared with those in the no fibrinogen group. CONCLUSIONS: Administering fibrinogen concentrate or cryoprecipitate was associated with neither thromboembolic events nor 30-day mortality in patients undergoing thoracic aortic surgery. Administering fibrinogen concentrate or cryoprecipitate is safe and does not appear to increase thromboembolic events and mortality in thoracic aortic surgery patients.

Optimal reconstruction of left ventricular outflow tract obstruction before surgical myectomy in a case with hypertrophic obstructive cardiomyopathy.

We present optimally reconstructed three-dimensional computed tomography images of left ventricular outflow obstruction, comprehensive left ventriculography, and comparable intraoperative transesophageal echocardiography, as well as serial operative pictures, to facilitate the understanding of live-heart anatomy of hypertrophic obstructive cardiomyopathy. As shown in this case, detailed morphological analysis around the left ventricular outflow tract using preoperative computed tomography would be feasible and useful. The present case highlights the importance of obtaining complete three-dimensional information present in the acquired computed tomography dataset because computed tomography is not entirely noninvasive or free of radiation exposure and contrast material.

Preoperative exercise capacity is associated with the prevalence of postoperative delirium in elective cardiac surgery.

BACKGROUND: Postoperative delirium (POD) is a critical complication that is closely associated with mortality and major morbidity in elective cardiac surgery. The identification of patients at risk for POD is crucial but has not been fully explored. AIMS: The aim of this study was to determine the predictive value of the assessment of preoperative exercise capacity for POD. METHODS: We enrolled 313 consecutive patients (mean age, 68.6 ± 14.8 years) undergoing elective cardiac surgery. We measured physical functions such as the 6-minute walking distance (6MWD) and Timed Up-and-Go test (TUG) before surgery. The assessment of delirium was conducted every 8 h from the day of surgery to 5 days after surgery using the Intensive Care Delirium Screening Checklist. RESULTS: POD occurred in 46 patients (14.6%). Age, 6MWD, TUG, serum hemoglobin, estimated glomerular filtration rate, and length of intensive care unit stay were significantly different based on the presence or absence of POD (p < 0.05 for each). After multivariate analysis, 6MWD remained a statistically significant indicator for developing POD (OR 0.98; p = 0.02). The cut-off value of 6MWD for predicting POD was 345 m (AUC = 0.75; p = 0.001). CONCLUSIONS: Poor exercise capacity was found to be an independent predictor of POD following elective cardiac surgery. This finding suggests the importance of preoperative functional evaluation in the prevention and management of POD in cardiac surgery patients.

Valve-sparing reimplantation for neoaortic root dilatation and regurgitation with an unbalanced cusp after the arterial switch operation.

A 13-year-old male presented with neoaortic root dilatation and severe aortic valve regurgitation 13 years following an arterial switch operation. The valve cusps were unbalanced due to an enlarged non-coronary cusp. A valve-sparing reimplantation with a cusp plication was performed which resulted in a competent valve with trivial regurgitation. Thus, even in an unbalanced cusp, valve-sparing reimplantation can be used for neoaortic root dilatation and valve regurgitation after an arterial switch operation.

[Aortic Valve Repair with Reimplantation in Small Aortic Root].

Annular fixation has an important role aortic valve repair for aortic regurgitation. We have used the reimplantation procedure as annular fixation combined with cusp repair rechniques for aortic valve repair even in small aortic root( <50 mm) since 2010. Freedom from aortic valve reoperation was 93% at 5 years and 79% at 8 years. Freedom from greater than moderate aortic regurgitation was 80% at 5 years and 71% at 8 years. Although the outcomes were not satisfactory and should be improved, this technique would be one of choices in selected patients, considering durability of bioprostheses and anticoagulation-related events in mechanical valves.

Significant Prognostic Value of Acute Preload Stress Echocardiography Using Leg-Positive Pressure Maneuver for Patients With Symptomatic Severe Aortic Stenosis Awaiting Aortic Valve Intervention.

BACKGROUND: Although aortic valve intervention is recommended for virtually all symptomatic patients with aortic stenosis (AS), how urgently the intervention should be performed remains controversial. The aim of this study was thus to determine whether the preload reserve in response to leg-positive pressure (LPP) maneuver could serve for decision-making for AS patients awaiting aortic valve intervention.Methods and Results:Sixty-eight patients with symptomatic AS, who were referred for aortic valve intervention, were recruited. Stroke volume (SV) was assessed by means of pulsed-wave Doppler, and the ratio between transmitral E wave and mitral annular velocity (e') was calculated to estimate ventricular filling pressure. While waiting for intervention, 11 patients experienced preoperative cardiac events. During acute preload stress, forward SV for patients without cardiac events increased significantly (from 43±9 to 49±10 mL/m2, P<0.01) along with a minimal change in filling pressure (E/e': from 20±8 to 21±9, NS). For patients with cardiac events, the Frank-Starling mechanism was significantly impaired (SVi: from 40±9 to 38±7 mL/m2, NS), while filling pressure increased to the critical level (E/e': from 24±8 to 31±8, P<0.001). Both the patients without flow reserve (∆SVi <4.5 mL/m2) and those without diastolic reserve (∆E/e' ≥2.9) exhibited significantly worse event-free survival than the others (P<0.05, respectively). CONCLUSIONS: Assessment of preload reserve during LPP stress could facilitate risk stratification of patients with severe AS waiting for aortic valve intervention.

Poor preoperative nutritional status is an important predictor of the retardation of rehabilitation after cardiac surgery in elderly cardiac patients.

BACKGROUND: Preoperative nutritional status and physical function are important predictors of mortality and morbidity after cardiac surgery. However, the influence of nutritional status before cardiac surgery on physical function and the progress of postoperative rehabilitation requires clarification. AIMS: To determine the effect of preoperative nutritional status on preoperative physical function and progress of rehabilitation after elective cardiac surgery. METHODS: We enrolled 131 elderly patients with mean age of 73.7 ± 5.8 years undergoing cardiac surgery. We divided them into two groups by nutritional status as measured by the Geriatric Nutritional Risk Index (GNRI): high GNRI group (GNRI ≥ 92, n = 106) and low GNRI group (GNRI < 92, n = 25). Physical function was estimated by handgrip strength, knee extensor muscle strength (KEMS), the Short Physical Performance Battery (SPPB), and 6-minute walk test (6MWT). Progress of postoperative rehabilitation was evaluated by the number of days to independent walking after surgery, length of stay in the ICU, and length of hospital stay. RESULTS: After adjusting for potential confounding factors, preoperative handgrip strength (P = 0.034), KEMS (P = 0.009), SPPB (P < 0.0001), and 6MWT (P = 0.012) were all significantly better in the high GNRI group. Multiple regression analysis revealed that a low GNRI was an independent predictor of the retardation of postoperative rehabilitation. CONCLUSIONS: Preoperative nutritional status as assessed by the GNRI could reflect perioperative physical function. Preoperative poor nutritional status may be an independent predictor of the retardation of postoperative rehabilitation in patients undergoing elective cardiac surgery.

Intact Imaging of Human Heart Structure Using X-ray Phase-Contrast Tomography.

Structural examination of human heart specimens at the microscopic level is a prerequisite for understanding congenital heart diseases. It is desirable not to destroy or alter the properties of such specimens because of their scarcity. However, many of the currently available imaging techniques either destroy the specimen through sectioning or alter the chemical and mechanical properties of the specimen through staining and contrast agent injection. As a result, subsequent studies may not be possible. X-ray phase-contrast tomography is an imaging modality for biological soft tissues that does not destroy or alter the properties of the specimen. The feasibility of X-ray phase-contrast tomography for the structural examination of heart specimens was tested using infantile and fetal heart specimens without congenital diseases. X-ray phase-contrast tomography was carried out at the SPring-8 synchrotron radiation facility using the Talbot grating interferometer at the bending magnet beamline BL20B2 to visualize the structure of five non-pretreated whole heart specimens obtained by autopsy. High-resolution, three-dimensional images were obtained for all specimens. The images clearly showed the myocardial structure, coronary vessels, and conduction bundle. X-ray phase-contrast tomography allows high-resolution, three-dimensional imaging of human heart specimens. Intact imaging using X-ray phase-contrast tomography can contribute to further structural investigation of heart specimens with congenital heart diseases.

Transition of intestinal fatty acid-binding protein on hypothermic circulatory arrest with cardiopulmonary bypass.

INTRODUCTION: Intestinal fatty acid-binding protein (I-FABP) is increasingly employed as a highly specific marker of intestinal necrosis. However, the value of this marker associated with cardiovascular surgery with hypothermic circulatory arrest is unclear. The aim of this study was to measure serum I-FABP levels and provide the transition of I-FABP levels with hypothermic circulatory arrest to help in the management of intestinal perfusion. METHODS: From August 2011 to September 2013, 33 consecutive patients who had aortic arch surgery with hypothermic circulatory arrest or heart valve surgery performed were enrolled in the study. Twenty patients had aortic surgery with hypothermic (23-29°C) circulatory arrest and 13 patients had heart valve surgery with cardiopulmonary bypass (33°C). RESULTS: I-FABP levels increased, both in patients undergoing aortic surgery with hypothermic circulatory arrest and heart valve surgery with cardiopulmonary bypass, reaching peak levels shortly after the administration of protamine. I-FABP levels in patients with aortic surgery were significantly higher with circulatory arrest. They reached peak levels immediately after recirculation and there was a significant drop at the end of surgery (p<0.001). I-FABP levels in heart valve surgery were gradually increased, with the highest at the administration of protamine; they gradually decreased. Peak I-FABP levels were significantly higher in patients undergoing aortic surgery with hypothermic circulatory arrest than in patients with heart valve surgery. However, no postoperative reperfusion injury occurred in the intestinal tract due to the use of hypothermic organ protection. CONCLUSION: Plasma I-FABP monitoring could be a valuable method for finding an intestinal ischemia in patients with cardiovascular surgery.

Endogenous superoxide dismutase activation by oral administration of riboflavin reduces abdominal aortic aneurysm formation in rats.

OBJECTIVE: Vitamin B2 (riboflavin) reportedly has an antioxidant effect through superoxide dismutase (SOD) activation. However, the effect of riboflavin on abdominal aortic aneurysm (AAA) has never been investigated. In the present study, we examined the hypothesis that riboflavin has a protective effect on AAA formation in an experimental rat model. METHODS: The AAA model, which was induced with intraluminal elastase and extraluminal calcium chloride, was created in 36 rats. The 36 rats were divided into a riboflavin group (group R; 25 mg/kg/d), and control group (carboxymethyl cellulose). Riboflavin administration by gastric gavage once per day was started at 3 days before aneurysm preparation. On day 3, SOD activity in aneurysm walls was assayed. On day 7, reactive oxygen species (ROS) levels were semiquantified by dihydroethidium staining, and the oxidation product of DNA produced by ROS, 8-hydroxydeoxyguanosine (8-OHdG), was measured by immunohistochemical staining. Histopathologic examination (hematoxylin/eosin and elastica Van Gieson staining) was performed on day 28, and the AAA dilatation ratio was calculated to evaluate the protective effect of riboflavin. RESULTS: On day 3, SOD activity was significantly increased in aneurysm walls by riboflavin administration (370 ± 204 U/mL in normal, 334 ± 86 U/mL in control, 546 ± 143 U/mL in group R; P = .021). On day 7, ROS levels and 8-OHdG-positive cells in aneurysm walls were significantly decreased by riboflavin treatment (ROS levels: 1.0 ± 0.1 in normal, 4.5 ± 0.4 in control, 3.1 ± 0.5 in group R, P < .01; 8-OHdG-positive cells: 30 ± 2 cells in normal, 148 ± 20 cells in control, 109 ± 15 cells in group R, P < .01). Riboflavin treatment significantly reduced matrix metalloproteinase (MMP)-9 messenger RNA expression in aneurysm walls (relative expression: MMP-9: 0.4 ± 0.7 in normal, 2.6 ± 1.3 in control, 0.5 ± 0.3 in group R, P < .01). On day 28, the aortic walls were less dilated and had higher elastin content in group R than in control (dilatation ratio: 194.9% ± 10.9% in control, 158.6% ± 2.5% in group R; P <.01). CONCLUSIONS: Riboflavin treatment prevents AAA formation in a rat model through an antioxidant effect and might be a potent pharmacologic agent for AAA treatment in clinical practice.