A New, Automated and Accurate In Vitro Method to Quantify Endothelial Cells Attached to Vascular Prostheses

Over a decade ago the idea of endothelial cell seeding was introduced in an attempt to improve the function of small caliber vascular prostheses. Although endothelial cell seeding is currently being applied clinically, several questions regarding the functional properties of the seeded endothelial cells remain. Evaluation of functional properties of endothelial cells on various types of vascular prostheses can be performed partly in vitro, but it is hampered by the fact that commonly used methods to quantify endothelial cells do not adequately apply to these cells on prosthetic materials.

An accurate quantification method is described that is rapidly and easily applicable to endothelial cells attached to vascular prostheses. The method can also be used to quantify endothelial cells attached to culture dishes or microcarriers. Colorless, non-fluorescing, fluorescein-di-acetate was used, which was taken up by the attached endothelial cells, and which was then intracellularly converted to yellow fluorescein, emitting green fluorescence. Subsequently, triton-X-100 was appli-cated to release fluorescein and levels of fluorescence were measured with the automated aperture-defined microvolume (ADM) method, using an inverted fluorescence microscope to which a photometer was connected. The measured level of fluorescence is linearly related to endothelial cell numbers attached to prostheses. The accuracy and the reproducibility of cell countings are high.

Quality of life from a randomized trial of open and endovascular repair for abdominal aortic aneurysm

Background

Long-term survival is similar after open or endovascular repair of abdominal aortic aneurysm. Few data exist on the effect of either procedure on long-term health-related quality of life (HRQoL) and health status.

Methods

Patients enrolled in a multicentre randomized clinical trial (DREAM trial; 2000–2003) in Europe of open repair versus endovascular repair (EVAR) of abdominal aortic aneurysm were asked to complete questionnaires on health status and HRQoL. HRQoL scores were assessed at baseline and at 13 time points thereafter, using generic tools, the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36®) and EuroQol 5D (EQ-5D™). Physical (PCS) and mental component summary scores were also calculated. Follow-up was 5 years.

Results

Some 332 of 351 patients enrolled in the trial returned questionnaires. More than 70 per cent of questionnaires were returned at each time point. Both surgical interventions had a short-term negative effect on HRQoL and health status. This was less severe in the EVAR group than in the open repair group. In the longer term the physical domains of SF-36® favoured open repair: mean difference in PCS score between open repair and EVAR −1·98 (95 per cent c.i. −3·56 to −0·41). EQ-5D™ descriptive and EQ-5D™ visual analogue scale scores for open repair were also superior to those for EVAR after the initial 6-week interval: mean difference −0·06 (−0·10 to −0·02) and −4·09 (−6·91 to −1·27) respectively.

Conclusion

In this study EVAR appeared to be associated with less severe disruption to HRQoL and health status in the short term. However, during longer-term follow-up to 5 years, patients receiving open repair appeared to have improved quality of life and health status.

Infection of endovascular abdominal aortic aneurysm stent graft after urosepsis: case report and review of the literature

Infection of endovascular abdominal aneurysm stent grafts is an uncommon but known complication. Inoculation with bacteria of the endovascular abdominal aneurysm stent graft during the actual implantation, in the periprocedural hospitalization or later due to an aortoenteric fistula, has been described in the literature. We report a case of endovascular abdominal aortic aneurysm stent graft infection occurring 40 months after implantation in a patient doing well up to an episode of urosepsis. In conclusion, we postulate that poor intraluminal healing of stent grafts, as observed in several explant studies, may result in a higher susceptibility to episodes of bacteremia than prosthetic vascular grafts inserted during open repair. We therefore consider the administration of prophylactic antibiotics in patients with endovascular stent grafts during periods with a likelihood of bacteremia.

[A measurable connection between preventative interventions and the incidence of postoperative wound infection]

OBJECTIVE

To establish whether there was a link between the preventative interventions executed and two groups of patients: those with and those without a postoperative wound infection (POWI).

DESIGN

Descriptive and comparative research.

METHOD

At Rijnland Hospital, a Dutch non-academic teaching hospital, 284 indicator operations were carried out between 1 April 2009 and 31 March 2010. We investigated whether preventative interventions were carried out during these operations. The types of surgery included mastectomy with and without axillary node dissection, resection of the colon and central vascular surgery (reconstruction of the aorta via an endovascular or open approach). Four types of intervention were studied: hygienic discipline (measurement of the number of times the operating theatre doors moved), the timely administration of preoperative antibiotic prophylactics, the avoidance of preoperative shaving and the attempts at perioperative normothermia. A 'postoperative wound infection' was registered as such if it had developed within 30 days of surgery.

RESULTS

In total, 22 POWIs (7.7%) were registered, arising from 284 operations: 5 POWIs (2.8%) after mammary surgery, 1 POWI (2.8%) after central vascular surgery, and 16 POWIs (21.6%) after colon surgery, respectively (see table 2). Meeting the criteria of all 4 types of intervention had no influence on the development of a POWI. A significant association to the development of a POWI was, however, determined to be the variables related to wound classification, duration of surgery and the average number of door movements per hour during surgery; specifically, 7 or more.

CONCLUSION

Surveillance by way of registration and feedback of interventions and their optimisation, particularly in terms of door movement, can possibly contribute to a reduction in the number of postoperative would infections.

[Endovascular prostheses and extra-anatomical bypasses to mesenteric and renal vessels in a patient with a thoraco-abdominal aortic aneurysm: a possible alternative to the standard operation]

A 57-year-old male had a thoraco-abdominal aortic aneurysm that was increasing in diameter, accompanied by pain in the right lower abdomen and groin. Ten years earlier he had had a dissecting thoraco-abdominal aneurysm that extended from the left subclavian artery to the aortic bifurcation. A CT-scan revealed further growth of the aneurysm. He was treated by an open and an endovascular operation. The distal aorta was replaced by a bifurcation prosthesis via a laparotomy, with 2 other bifurcation prostheses to 2 mesenteric and 2 renal arteries. In a second session, a carotid-subclavian bypass was constructed and the aorta was reinforced by an endograft from the left subclavian artery to the bifurcation prosthesis. Postoperatively he suffered a transient ischaemic attack, hypertension, pneumonia, and vocal cord paresis. At follow-up 1.5 years later, the patient was free of symptoms, with the exception of slight hoarseness during forced speech, and the aneurysm was totally under control. This procedure may be an alternative to the classical thoracophrenicolaparotomy.

Effect of intraluminal thrombus on pressure transmission in the abdominal aortic aneurysm

OBJECTIVE

To clarify the effect of intraluminal thrombus on pressure transmission.

METHODS

A saccular aneurysm was inserted into an artificial circulation system. Subsequently, the saccular aneurysm was filled with eight different human aortic aneurysm thrombus samples. Starch solution in an empty aneurysm was used as a control. A pressure sensor measured the pressure in the circulation, and a second piezoelectric sensor measured the pressure in the saccular aneurysm at 3, 2, and 1 cm from the endoluminal surface (23 locations). The influence of the elastic characteristics of the aneurysm wall on the extent of pressure reduction was evaluated by experiments performed with aneurysms made of rubber and paraffin.

RESULTS

The pressures measured in the empty aneurysm were identical to those measured in circulation (P > .05). The pressure measured in the thrombus was significantly lower than the pressure measured in the circulation (P < .05). The mean pressure ratio between the systolic thrombus pressure and systolic circulation pressure at 1, 2, and 3 cm was 0.90 +/- 0.09, 0.86 +/- 0.10, and 0.81 +/- 0.09, respectively. However, there was a clear correlation between the pressure in the circulation and in the thrombus (Pearson correlation coefficient: mean, r = 0.997; range, 0.975-0.999; P < .01). The change in circulatory pressure was followed by an almost identical change in thrombus pressure (regression coefficient: mean, beta = .997; range, .983-1.000; P < .01). In stiff aneurysms, the pressure reduction is less than in more compliant ones (P < .05).

CONCLUSIONS

In an in vitro model, pressure in the aneurysmal sac is reduced by fibrinous thrombus.

CLINICAL RELEVANCE

Endovascular aneurysm repair (EVAR) aims at reducing the pressure in the aneurysmal sac. Therefore, it seems attractive to use pressure monitoring in the aneurysmal sac as a follow-up after EVAR. This study contributes to the development of the rationale of pressure monitoring in the aneurysmal sac as a follow-up method after EVAR. The aneurysmal sac is filled with thrombus. To interpret pressure measurements in the thrombus, we have to learn about the effect of the thrombus on pressure transmission and on the pressure measurements themselves. Our study demonstrates that reduction of pressure occurs as it is transmitted through a human aortic thrombus.

Aneurysm Sac Pressure Monitoring: Effect of Technique on Interpretation of Measurements

OBJECTIVES

The purpose of this study is to determine the accuracy of measuring pressure with a fluid filled pressure device (needle) and a non-fluid filled pressure device (catheter) inside a thrombosed aneurysmal sac after exclusion from circulation by endovascular grafting.

METHODS

In a static environment, consisting of a syringe to which a pressure monitoring kit was connected, experiments were performed to study the influence of the type of device (either needle or catheter) and the effect of the characteristics of the medium on the accuracy and reproducibility of pressure measurements. The pressures obtained with the needle in the different kinds of media were compared with those obtained in blood. Similar experiments were performed using a pressure catheter. Subsequently, pressure measurements were performed in a dynamic and physiological environment. This environment consisted of an artificial circulation in which an aneurysm, constructed of porcine aorta and filled with human aortic thrombus, was mounted. The pressures were compared and analyzed by Bland-Altman plots.

RESULTS

Under static conditions, the pressure levels obtained by a needle in blood, starch solution and thrombus were similar. Under identical conditions, pressures obtained by a catheter in starch solution were significant lower than the pressures measured in blood (P<0.05). Under dynamic pressure conditions the reproducibility of pressures obtained with the needle inserted in the human thrombus was very poor.

CONCLUSION

A needle pressure measuring device, inserted into media like human fibrin thrombus, does not yield accurate and reproducible results. A catheter with a tip-sensor rather than a needle is superior to study the pressure in the aneurysm sac after EVAR.

Ingrowth of aorta wall into stent grafts impregnated with basic fibroblast growth factor: a porcine in vivo study of blood vessel prosthesis healing

OBJECTIVE

Endovascular aneurysm repair is an alternative treatment of abdominal aortic aneurysm. The procedure is less invasive, and morbidity and most probably mortality are reduced. However, some problems, such as endoleakage, are yet to be resolved. Endoleakage can occur after graft migration, as a result of insufficient fixation of the stent graft. One cause is deficient healing between the aortic neck and the stent graft. We hypothesize that better healing, achieved by induction of vascular cell ingrowth into the graft material, results in better graft fixation. Previously we demonstrated ingrowth of neointima into the graft material if the stent graft is impregnated with a coat of basic fibroblast growth factor (bFGF), heparin, and collagen. In this study we evaluated healing with bFGF-heparin-collagen-coated stent grafts in vivo.

METHODS

In 4 pigs, 32 endovascular stent grafts, manufactured from standard Dacron and Gianturco Z-stents, were placed in the aorta. The stent grafts were impregnated with either bFGF-heparin containing collagen (n=16) or control collagen (n=16). After 4 and 8 weeks animals were killed, and ingrowth and healing of the stent grafts were macroscopically and electron microscopically evaluated.

RESULTS

After 8 weeks all bFGF-impregnated stent grafts demonstrated ingrowth of tissue and healing between the graft and the aorta, whereas the control nonimpregnated stent grafts showed no ingrowth. Microscopic evaluation demonstrated alpha-smooth muscle actin-positive cells, most probably smooth muscle cells or myofibroblasts, growing from the vascular wall through the graft material.

CONCLUSION

A Dacron prosthesis impregnated with collagen, heparin, and bFGF induced graft healing in an in vivo pig model, in contrast to nonimpregnated stent grafts. This in vivo study confirms our previous findings in vitro. These results indicate that healing between Dacron and the aorta can be achieved, and suggest that type I endoleakage may be resolved by inducing healing between the aortic wall and the prosthesis with graft material containing growth factor.

Accessory thyroid gland at carotid bifurcation presenting as a carotid body tumor: case report and review of the literature

Patients with carotid body tumors referred to vascular surgeons usually undergo magnetic resonance imaging (MRI) as part of the workup. We present a case report of a 39-year-old woman with a presumed carotid body tumor, as was expected from clinical and MRI findings. At surgery, the ectopic thyroid tissue was suspected, and resection was performed. Histologic examination showed normal thyroid tissue with no sign of malignancy. Postoperative thyroid analysis showed a normally located, properly functioning thyroid gland. Ectopic thyroid glands are generally found in the midline, as a result of abnormal median migration. Their presence lateral to the midline with a proper functioning thyroid gland in its normal position is extremely rare. Although several submandibular thyroid glands have been reported, a close relation with the carotid arteries was described only once. When MRI scans of a presumed carotid body tumor show tumor characteristics that are not fully specific for a carotid body tumor, the possibility of ectopic thyroid tissue should be entertained, which can be the patient's only properly functioning thyroid tissue. In such cases, additional assessment, including thyroid tests, should be considered before surgery.