Experimental comparative study of thrombogenicity of two differently luminal heparinized ePTFE vascular prosthetics.

INTRODUCTION: ; Heparin bonded grafts have proven to improve patency, at least transiently.Two different heparin bonded expanded polytetrafluoroethylene (ePTFE) grafts produced by different technologies are currently available.This pilot primary goal was to test these commonly used, but differently heparinized ePTFE grafts for differences in primary patency after a 6-months follow-up in a sheep model. Secondly, the aim was to establish a large animal model to enable future translational studies and further graft development. METHOD: ; End-to-side bypass of the common carotid artery was performed bilaterally in sheep. Either a Gore® Propaten heparinized graft or a Jotec® Flowline Bipore heparinized graft was used, both 5 mm in diameter.Following graft implantation, the sheep were kept on pasture for 6 months, with monthly duplex scans to determine patency. At termination, the grafts were duplex scanned a final time, with the animals sedated, and the grafts were removed for heparin activity analysis. RESULTS: ; 14 sheep were operated, 11 survived total follow-up time. At final follow-up, 4 patent Gore® grafts, and 6 Jotec® remained. Mean patency time was 106.7 ±â€¯21.9(SD) days and 96.2 ±â€¯25.9(SD) days for Gore® and Jotec®, respectively. Log-rank test showed no significant difference at final follow-up after 6 months. Post mortem heparin analysis showed no significant difference in mean activity. CONCLUSION: ; Based on patency data alone, no significant difference between these grafts were found. In accordance, heparin activity analysis showed no difference between the grafts. The model itself, proved easily implementable, and provides many possibilities for future studies, though some adjustments should be made to improve survival.

Superior Reproducibility of the Leading to Leading Edge and Inner to Inner Edge Methods in the Ultrasound Assessment of Maximum Abdominal Aortic Diameter.

OBJECTIVES: Controversy exists regarding optimal caliper placement in ultrasound assessment of maximum abdominal aortic diameter. This study aimed primarily to determine reproducibility of caliper placement in relation to the aortic wall with the three principal methods: leading to leading edge (LTL), inner to inner edge (ITI), and outer to outer edge (OTO). The secondary aim was to assess the mean difference between the OTO, ITI, and LTL diameters and estimate the impact of using either of these methods on abdominal aortic aneurysm (AAA) prevalence in a screening program. METHODS: Radiologists (n=18) assessed the maximum antero-posterior abdominal aortic diameter by completing repeated caliper placements with the OTO, LTL, and ITI methods on 50 still abdominal aortic images obtained from an AAA screening program. Inter-observer reproducibility was calculated as the limit of agreement with the mean (LoA), which represents expected deviation of a single observer from the mean of all observers. Intra-observer reproducibility was assessed averaging the LoA for each observer with their repeated measurements. Based on data from an AAA screening trial and the estimated mean differences between the three principal methods, AAA prevalence was estimated using each of the methods. RESULTS: The inter-observer LoA of the OTO, ITI, and LTL was 2.6, 1.9, and 1.9 mm, whereas the intra-observer LoA was 2.0, 1.6, and 1.5 mm, respectively. Mean differences of 5.0 mm were found between OTO and ITI measurements, 2.6 mm between OTO and LTL measurements, and 2.4 mm between LTL and ITI measurements. The prevalence of AAA almost doubled using OTO instead of ITI, while the difference between ITI and LTL was minor (3.3% vs. 4.0% AAA). CONCLUSIONS: The study shows superior reproducibility of LTL and ITI compared with the OTO method of caliper placement in ultrasound determination of maximum abdominal aortic diameter, and the choice of caliper placement method significantly affects the prevalence of AAAs in screening programs.

Induction of autoimmune abdominal aortic aneurysm in pigs - A novel large animal model.

BACKGROUND: Abdominal aortic aneurysm (AAA) is a common disease with a high mortality. Many animal models have been developed to further understand the pathogenesis of the disease, but no large animal model has been developed to investigate the autoimmune aspect of AAA formation. The aim of this study was to develop a large animal model for abdominal aortic aneurysm induction through autoimmunity by performing sheep-to-pig xenotransplantation. METHODS: Six pigs underwent a xenotransplantation procedure where the infrarenal porcine aorta was replaced by a decellularized sheep aorta. In the following 47 days, the AP-diameter of the xenografts was measured using ultrasound once a week. All xenografts were harvested for histological analyses. RESULTS: All the xenografts formed aneurysms with a mean increase in AP-diameter of 80.98 ± 30.20% (p < 0.005). The ultrasound measurements demonstrated a progressive aneurysmal expansion with no sign of halting towards the end of the follow-up period. Histology showed destruction of tunica media and the elastic tissue, neointimal hyperplasia, adventitial thickening with neovascularization, infiltration of lymphocytes and granulocytes, and in some cases intramural haemorrhaging. CONCLUSION: We developed a novel large animal AAA model by infrarenal aortic sheep-to-pig xenograph transplantation resulting in autoimmune AAA induction with continuously progressive aneurysmal growth. This model can be used to provide a better understand the autoimmune aspect of AAA formation in large animals.

Systemic thioridazine in combination with dicloxacillin against early aortic graft infections caused by Staphylococcus aureus in a porcine model: In vivo results do not reproduce the in vitro synergistic activity.

INTRODUCTION: Conservative treatment solutions against aortic prosthetic vascular graft infection (APVGI) for inoperable patients are limited. The combination of antibiotics with antibacterial helper compounds, such as the neuroleptic drug thioridazine (TDZ), should be explored. AIM: To investigate the efficacy of conservative systemic treatment with dicloxacillin (DCX) in combination with TDZ (DCX+TDZ), compared to DCX alone, against early APVGI caused by methicillin-sensitive Staphylococcus aureus (MSSA) in a porcine model. METHODS: The synergism of DCX+TDZ against MSSA was initially assessed in vitro by viability assay. Thereafter, thirty-two pigs had polyester grafts implanted in the infrarenal aorta, followed by inoculation with 106 CFU of MSSA, and were randomly administered oral systemic treatment with either 1) DCX or 2) DCX+TDZ. Treatment was initiated one week postoperatively and continued for a further 21 days. Weight, temperature, and blood samples were collected at predefined intervals. By termination, bacterial quantities from the graft surface, graft material, and perigraft tissue were obtained. RESULTS: Despite in vitro synergism, the porcine experiment revealed no statistical differences for bacteriological endpoints between the two treatment groups, and none of the treatments eradicated the APVGI. Accordingly, the mixed model analyses of weight, temperature, and blood samples revealed no statistical differences. CONCLUSION: Conservative systemic treatment with DCX+TDZ did not reproduce in vitro results against APVGI caused by MSSA in this porcine model. However, unexpected severe adverse effects related to the planned dose of TDZ required a considerable reduction to the administered dose of TDZ, which may have compromised the results.

Low-dose aspirin and rupture of abdominal aortic aneurysm.

OBJECTIVE: The use of low-dose aspirin (acetylsalicylic acid [ASA]) has been suggested to attenuate growth of abdominal aortic aneurysms (AAAs), yet solid clinical evidence of this hypothesis is still missing. This study aimed to investigate whether preadmission ASA use influenced the risk of presenting with rupture of AAA (rAAA) on hospital admission and subsequent 30-day case fatality. METHODS: There were 4010 patients with an incident diagnosis of rAAA and 4010 age- and sex-matched AAA patients identified in the Danish National Registry of Patients. Data on comorbidity, concomitant drug use, primary health care utilization, socioeconomic status, and vital status were obtained from nationwide health care and administrative registries. RESULTS: Preadmission ASA use was identified for 1815 (45.3%) rAAA patients and 2111 (52.6%) AAA patients, corresponding to a crude odds ratio for rAAA in ASA users of 0.72 (95% confidence interval [CI], 0.66-0.79) compared with nonusers. However, after adjustment for possible confounders, no association between ASA use and the risk of rAAA was found (adjusted odds ratio, 0.97; 95% CI, 0.86-1.08). The aggregated 30-day rAAA case-fatality rate for users of ASA was 66.0% compared with 56.9% for nonusers, corresponding to an adjusted mortality rate ratio of 1.16 (95% CI, 1.06-1.27). CONCLUSIONS: Preadmission ASA use is not associated with an altered risk of AAA rupture but seems to be associated with a worse prognosis after rupture of AAA.