Pharmacotherapy for critical limb ischaemia

Critical limb ischaemia involves a severe disturbance of both macrocirculation and microcirculation. Provided revascularisation can be performed (balloon angioplasty, bypass procedures or other reopenings), the major pharmacological problem is to reduce the risk of early thrombosis and midterm hyperplastic growth. Adjuvant treatment for the former is useful, while the latter has not yet found any specific solution. When no technical prerequisites exist for revascularisation, which means extremely deranged vascular morphology, pharmacotherapy can be tried to reduce the specific micro-circulatory events. Results are far from good, though significant reduction of amputations and deaths may be achieved with certain drugs.

Endovenous management of saphenous vein reflux. Endovenous Reflux Management Study Group

PURPOSE

This study assessed clinical outcomes of two catheter-based endovenous procedures to eliminate or greatly mitigate saphenous vein reflux.

MATERIALS AND METHODS

A computer-controlled, dedicated generator and two catheter designs were used to treat 210 patients at 16 private clinic and university centers in Europe. The Closure catheter applied resistive heating over long vein lengths to cause maximum wall contraction for permanent obliteration; the Restore catheter induced a short subvalvular constriction to improve the competence of mobile but nonmeeting leaflets.

RESULTS

Closure treatment caused acute obliteration in 141 (93%) of 151 limbs; Restore treatment, shrinking one or more valves, acutely reduced reflux to less than 1 second in 41 (60%) of 68 limbs. Closure treatments were associated with early recanalization (6%), paresthesias (thigh, 9%; leg, 51%; P <.001), 3 skin burns, and 3 deep-vein thrombus extensions, with 1 embolism. Restore treatments were thrombogenic (16%) despite prophylactic anticoagulation, and treated valves enlarged over 6 weeks, becoming less competent. Clinical Efficacy Assessment Project clinical class was significantly improved after both treatments, up to 1 year. At 6 months, 87% of 53 Closure patients were class 0 or 1, 75% were symptom-free, and 96% of 55 treated limbs were completely free of reflux. Fourteen of 31 Restore patients (45%) had no symptoms, but 55% were class 2 or lower and only 19% had less than 1-second reflux.

CONCLUSION

Closure treatment is clinically effective, albeit with offsetting complications and early failures; these are being addressed through four procedural modifications. Restore valve shrinking, although conceptually attractive, is too problematic to be competitive with Closure treatment or saphenectomy.

MR evaluation ex vivo and in vivo of a covered stent-graft for abdominal aortic aneurysms: ferromagnetism, heating, artifacts, and velocity mapping

Magnetic resonance imaging (MRI) safety was evaluated at 1.5 T in a covered nickel titanium stent-graft (Vanguard) used for endovascular treatment of abdominal aortic aneurysms (AAAs). Imaging artifacts were assessed on MRI with contrast-enhanced (CE) three-dimensional (3D) MR angiography (MRA) and spiral computed tomography (CT) in 10 patients as well as ex vivo. Velocity mapping was performed in the suprarenal aorta and femoral arteries in 14 patients before and after stent-graft placement. For comparison it was also performed in six healthy volunteers. No ferromagnetism or heating was detected. Metal artifacts caused minimal image distortion on MRI/MRA. The artifacts disturbed image evaluation on CT at the graft bifurcation and graft limb junction. No significant differences in mean flow were found in patients before and after stent-graft placement. Our study indicates that MRI at 1.5 T may be performed safely in patients with the (Vanguard) stent-graft. MRI/MRA provides diagnostic image information. Velocity mapping is not included in our routine protocol.

First-generation aortic endografts: analysis of explanted Stentor devices from the EUROSTAR Registry

PURPOSE

To examine the structure and healing characteristics of chronically implanted Stentor endografts that were explanted due to migration, endoleak, thrombosis, or aneurysm expansion.

METHODS

The devices were harvested following reoperation (n = 5) or autopsy (n = 1) with implantation times ranging from 13 to 53 months. Structural modifications to the metal components were examined using radiography, endoscopy, and magnetic resonance imaging (MRI). Specimens taken from components of the modular stent-grafts were examined histologically and with scanning electron microscopy (SEM) to assess healing behavior. Physical and chemical stability of the nitinol wires and woven polyester graft material was evaluated using SEM and electron spectroscopy for chemical analysis.

RESULTS

Although the endografts were retrieved for a variety of reasons, they exhibited similar healing and structural modifications. The woven polyester sleeve showed evidence of yarn shifting and distortion, yarn damage, and filament breakage leading to the formation of openings in the fabric. The luminal surface endografts showed incomplete healing characterized by a poorly organized, nonadherent thrombotic matrix of variable thickness. Radiographic and endoscopic observations indicated that structural failure of the grafts, particularly in the main aortic component, was related to severe compaction and dislocation of the metallic frame due to suture breaks. Corrosion marks were observed on some nitinol wires in all devices. Chemical analysis and ion bombardment of the nitinol wires revealed that the surface concentrations of titanium and nickel were not homogenous. The first layer was composed of carbon or organic elements, followed by a stratum of highly oxidized titanium with a low nickel concentration; the titanium-nickel alloy lay beneath these layers.

CONCLUSIONS

Although the materials selected for construction of endovascular grafts appears judicious, the assembly of these biomaterials into various interrelated structures within the device requires further improvement.

First-generation aortic endografts: analysis of explanted Stentor devices from the EUROSTAR Registry

PURPOSE

To examine the structure and healing characteristics of chronically implanted Stentor endografts that were explanted due to migration, endoleak, thrombosis, or aneurysm expansion.

METHODS

The devices were harvested following reoperation (n = 5) or autopsy (n = 1) with implantation times ranging from 13 to 53 months. Structural modifications to the metal components were examined using radiography, endoscopy, and magnetic resonance imaging (MRI). Specimens taken from components of the modular stent-grafts were examined histologically and with scanning electron microscopy (SEM) to assess healing behavior. Physical and chemical stability of the nitinol wires and woven polyester graft material was evaluated using SEM and electron spectroscopy for chemical analysis.

RESULTS

Although the endografts were retrieved for a variety of reasons, they exhibited similar healing and structural modifications. The woven polyester sleeve showed evidence of yarn shifting and distortion, yarn damage, and filament breakage leading to the formation of openings in the fabric. The luminal surface endografts showed incomplete healing characterized by a poorly organized, nonadherent thrombotic matrix of variable thickness. Radiographic and endoscopic observations indicated that structural failure of the grafts, particularly in the main aortic component, was related to severe compaction and dislocation of the metallic frame due to suture breaks. Corrosion marks were observed on some nitinol wires in all devices. Chemical analysis and ion bombardment of the nitinol wires revealed that the surface concentrations of titanium and nickel were not homogenous. The first layer was composed of carbon or organic elements, followed by a stratum of highly oxidized titanium with a low nickel concentration; the titanium-nickel alloy lay beneath these layers.

CONCLUSIONS

Although the materials selected for construction of endovascular grafts appears judicious, the assembly of these biomaterials into various interrelated structures within the device requires further improvement.

Intraoperative contamination of synthetic vascular grafts. Effect of glove change before graft implantation. A prospective randomised study

OBJECTIVES

to investigate the incidence of intraoperative graft contamination, bacterial species and the influence of change of surgeon's gloves on contamination.

DESIGN

a prospective randomised study.

MATERIALS AND METHODS

forty patients had implantation of synthetic vascular grafts. All patients received intraoperative cloxacillin (2.0 g) or clindamycin (0.6 g) intravenously. The procedures were randomised to two groups: Group 1 - surgeons changed the gloves before the first contact with the vascular prosthesis and Group 2 - operation without glove change. The growth of all bacterial species from graft segments and from the gloves was recorded. The susceptibility to antibiotics was tested.

RESULTS

the number of contaminated grafts was similar in the two groups. Growth of bacteria was recorded from 92.5% (37/40) of the graft segments and 33% (51/156) of glove imprints. Of the cultured species, 75% and 47%, respectively, were identified as coagulase-negative staphylococci (CNS). Twenty-eight per cent of CNS were resistant to cloxacillin, 15% to clindamycin, and 10% to cloxacillin and clindamycin. In all, 25% of the CNS strains were resistant to the prophylactic antibiotic used. In 50% of cases, the antibiogram of the CNS strain recovered from gloves agreed with that of the strain harvested from the graft.

CONCLUSIONS

a high incidence of graft contamination was found which was not reduced by changing gloves. However, changing gloves did seem to reduce the number of bacterial species.

Microdialysis of the spinal cord during thoracic aortic cross-clamping in a porcine model

OBJECTIVE

Utilising microdialysis to measure the changes of glucose, lactate, pyruvate and glutamate levels in the spinal cord after cross-clamping of the thoracic aorta in an established porcine model to monitor the degree of ischaemia.

DESIGN

Experimental study with a porcine model.

SETTING

University Hospital, Trondheim.

SUBJECTS

Six pigs.

MAIN OUTCOME MEASURE

Lactate, pyruvate and glutamate concentrations in the microdialysis perfusate from the spinal cord.

RESULTS

A significant increase of the lactate-pyruvate ratio during the last 30 min of the 1 h clamping period, with a maximum increase of 169% from the basal value the last 10 min before declamping. No evident change in this ratio between the clamping and the reperfusion period. No significant change in glutamate levels during clamping or reperfusion period.

CONCLUSION

Microdialysis reflects the ischaemic state of the spinal cord during cross-clamping of the thoracic aorta in pigs, and is well suited to study each phenomena.

Percutaneous transluminal angioplasty with or without stenting for femoropopliteal occlusions? A randomized controlled study

BACKGROUND

To investigate the-one year outcome of PTA and stenting and PTA alone for femoropopliteal occlusions.

DESIGN

Randomized prospective study

METHODS

32 patients with femoropopliteal occlusions were randomized into two treatment groups: PTA and Strecker-stent (n=15) and PTA alone (n=17). The median age of the patients was 71 years. All patients had chronic limb ischaemia, 66% had tissue loss, 19% had rest pain and 15% had disabling claudication. The median ABPI was 0.45. The occlusion was confined to the superficial femoral artery in 30 cases and to the popliteal artery in 2 cases. The median length of the occlusions was 7.3 cm. Aspirin (ASA), 160 mg daily, was administrated postoperatively but no anticoagulation was used. The follow-up included: clinical examination, measurement of ABPI and control angiography at 12 months or earlier when necessary (20 patients).

RESULTS

There was no mortality or limb loss as a consequence of the treatment. There were six (16%) immediate major complications in five patients. In the PTA group, one patient had a myocardial infarction and three patients needed arteriography due to bleeding. In the stent group, one patient required arteriography and embolectomy. The one-year mortality was 6% and there were no amputations. Four patients (two in each group) were operated on with a femorodistal bypass. The rate of clinical improvement was 71% after PTA and stent and 60% after PTA alone (p=0.17). An increased ABPI (>0.10) was shown in 50% of the stent group and 61% in the PTA group (p=0.17). Angiographic re-occlusions were seen in 33% and 75% in the stent and PTA groups respectively (p=0.17), while the rate of restenosis was significantly higher in the stent group (50% vs 25%) (p=0.033).

CONCLUSIONS

Stenting following PTA for femoropopliteal occlusions does not significantly improve neither the clinical state nor the clinical/angiographic patency. The results do not justify any routine placement of stent following PTA in the successfully recanalized femoropopliteal arteries. The low rate of acceptance of a follow-up angiography indicates that this kind of study should preferably use duplex scanning instead of angiography for follow-up.

Diabetes mellitus as a risk factor for early outcome after carotid endarterectomy--a population-based study

BACKGROUND AND PURPOSE

to determine if diabetes mellitus is a risk factor for outcome after carotid endarterectomy (CEA).

METHODS

the outcome and complications of all vascular procedures performed in Sweden are registered prospectively in the Swedish Vascular Registry (Swedvasc) and form the basis of this report. During the 10-year period 1987-96 2622 CEAs were analysed for notified complications.

RESULTS

of the 2622 CEAs, 341 (13%) were performed on diabetics and 2281 (87%) on non-diabetics. Patients with diabetes presented at a younger age (67.1+/-8.3 years vs. 68.2+/-8.3 years p =0.028), were more likely to have a history of hypertension (61.9% vs. 50% p =0.001) and were less often smokers (34.9% vs. 43.2% p =0.001). Diabetics presented more often with minor stroke (41.3% vs. 30.8% p =0.002) and non-diabetics more often with amaurosis fugax (18.9% vs. 14.4% p =0.04). Diabetics had a higher 30-day mortality (3.2% vs. 1. 4% p =0.02). The 30-day neurologic and cardiac morbidity did not differ. The 1-year mortality was 7.9% in diabetics and 4.4% in non-diabetics (p =0.008). Non-diabetics operated on in 1992-96 compared to those operated on in 1987-91 had a significantly lower combined permanent stroke and death rate (3.7% vs. 5.7% p =0.05), a difference not found in diabetics (6.3% for 1987-92 and 6.8% for 1992-96; N.S).

CONCLUSIONS

diabetics had both a higher 30-day and 1-year mortality after CEA compared to non-diabetics, mainly because of cardiac complications. However, postoperative neurologic morbidity did not differ.

Chronic venous disorders of the leg: epidemiology, outcomes, diagnosis and management. Summary of an evidence-based report of the VEINES task force. Venous Insufficiency Epidemiologic and Economic Studies

BACKGROUND

To critically review the classification, epidemiology, outcomes, diagnosis and treatment of chronic venous disorders of the leg (CVDL), to issue evidence-based recommendations, and to identify areas requiring further research.

METHODS

Articles identified by an extensive literature search were scored by members of an international task force. Only those articles with a moderate or strong rating for internal validity were retained.

RESULTS

A scoring system weighing CVDL severity according to the probability of ulcer occurrence is proposed. Epidemiological data on the frequency of CVDL and its risk factors are reviewed. The following items are evaluated: costs associated with treatment; clinical outcomes related to CVDL and its treatment; available generic and disease-specific measures of quality of life; diagnostic procedures used to detect venous reflux; and efficacy of available treatments.

CONCLUSIONS

CVDL is an important public health problem, based on its prevalence, cost and impact on quality of life. High-priority areas for research on CVDL are identified.

Relationship of femorodistal bypass patency to clinical outcome. Iloprost Bypass International Study Group

OBJECTIVE

To investigate the relationship between bypass patency, limb survival and clinical symptoms after femorodistal bypass procedures.

DESIGN

Multicentre, prospectively planned 12-month postoperative follow-up.

PATIENTS AND METHODS

Five hundred and seventeen patients undergoing femorodistal bypass surgery for severe ischaemia. Clinical symptoms, bypass patency were recorded at regular intervals up to 12 months postoperatively.

RESULTS

Complete follow-up data was obtained on 498 patients (96%). Fifty-six (17%) of the 341 patients with patent bypasses had either rest pain or ulcers or had undergone major amputation at 12 months. Of the 167 patients with an occluded bypass, 22 patients (13%) had improved clinical symptoms and a total of 59 patients (35%) had avoided major amputation at 12 months. The clinical outcome for patients classified preoperatively as Fontaine stage IV was significantly worse than for those in stage III preoperatively despite similar bypass patency rates.

CONCLUSIONS

There is a fair correlation between technical and clinical outcome after femorodistal bypass surgery at 12 months, but there are significant numbers of patients with occluded bypasses who have a good clinical outcome and of patients with patent bypasses who have a poor clinical outcome. The reporting of symptoms in addition to bypass patency would aid the interpretation of surgical results.

Adverse reactions during endovascular treatment of aortic aneurysms may be triggered by interleukin 6 release from the thrombotic content

PURPOSE

It has been shown that endovascular aortic aneurysm repair might induce a significant inflammatory response, mainly involving tumor necrosis factor (TNF-alpha) release. This study determined in vitro whether these inflammatory responses could depend on white blood cell (WBC) activation caused by the aneurysmal mural thrombus.

METHODS

Mural thrombus specimens obtained from 10 different aortic aneurysms were weighed, homogenized, and assayed for interleukin 1beta (IL-1beta), interleukin 6 (IL-6), TNF-alpha, and soluble TNF receptor (sTNFRI).

RESULTS

Only high amounts of IL-6 (mean, 2973 pg/mL) were found. In contrast, after the addition of healthy donor WBCs to the thrombus mass supernatants, elevated levels of TNF-alpha (mean, 523 pg/mL) were seen. Theoretically, WBCs were stimulated by IL-6, resulting in TNF-alpha release. In additional experiments, it was proven that stimulated WBCs, induced by thrombus mass supernatants, synthesize TNF-alpha (mean, 796 pg/mL), and monoclonal antibodies against IL-6, prevented such TNF-alpha production (mean, 62 pg/mL).

CONCLUSION

The biologic responses during endovascular repair may be explained by a release of IL-6 from the aneurysmal thrombus, causing WBC stimulation and production of TNF-alpha. More complex processes cannot be excluded, but the present findings suggest that restrictions of manipulations within the aneurysm may be advisable.

[Significant regional differences in the frequency of vascular surgery]

The six health care regions of Sweden were compared with regard to the frequency of vascular surgery for three diagnoses: chronic lower extremity ischaemia, abdominal aorta aneurysm, and carotid stenosis. In 1995, the frequency of intervention for chronic lower extremity ischaemia varied from 26/100,000 of the population in northern Sweden to 68/100,000 in the southern region, the variation being greater for critical limb ischaemia than for intermittent claudication. In the country as a whole, the frequency of abdominal aorta aneurysm surgery increased five-fold from 1987-89 to 1993-95. During 1995, regional figures varied from 4.7 to 8.4 per 100,000 for elective procedures, and from 3.8 to 5.5 per 100,000 for emergency procedures. Overall surgical mortality varied regionally, and emergency surgery mortality differed between regional and county hospitals. Carotid surgery manifested the greatest regional difference in frequency, which was 7-fold greater in the southern than in the northern region, while its overall mean frequency was 6/100,000.

Aortoenteric fistula caused by a ruptured stent-graft: a case report

PURPOSE

To report a case of aortoenteric fistula secondary to endovascular abdominal aortic aneurysm (AAA) exclusion using the Stentor bifurcated endovascular graft.

METHODS AND RESULTS

Seventeen months after a successful endovascular AAA procedure, a male patient developed upper gastrointestinal bleeding. An aortoenteric fistula was diagnosed. At operation, the endograft fabric was found to be ruptured in an area of suture disruption between the nitinol stents. Coincidentally, a pre-existing inflammatory process might have caused adhesions between the bowel and the aortic wall, predisposing to fistula formation. The patient recovered after placement of a conventional aortic graft.

CONCLUSIONS

Suture disruption between the internal support stents is a recognized complication in the first-generation Stentor device. Although the case described here is probably not typical of the consequences of this sequela, it does reinforce the need for continual periodic imaging to check for signs of graft disruption in Stentor endografts.

Outcome and influence of age after infrainguinal revascularisation in critical limb ischaemia. The Swedish Vascular Registry

OBJECTIVES

To evaluate whether revascularisation has any influence on the mortality rate, and the impact of old age in patients with critical limb ischaemia (CLI).

DESIGN

Analysis of Swedish Vascular Registry (Swedvasc) data.

PATIENTS AND METHODS

During 1987-1995, 3730 surgical and 1199 endovascular (PTA) procedures below the groin due to CLI were reported. At 1 year three groups were defined: "occluded, amputated"; "occluded, not amputated" and "patent". Survival was also calculated. Clinical outcome at 1 month and at 1 year was defined as: patient "alive, improved", "alive, not improved", "alive, amputated" and "dead". Two age groups < or = 75 years or and > or = 76 years were compared.

RESULTS

The mortality rate for the whole group was 5.3% at 1 month and 22.9% at 1 year, with no difference between the Surgery and PTA groups. Significantly more patients were alive and improved after surgery than after PTA at 1 month (82.3% vs. 77.7%) and at 1 year (49.6% vs. 44.3%). The amputation rate was 5.6% at 1 month and 14.4% at 1 year; 17% for diabetics. After surgery, the cumulative mortality rate did not differ between patients with a salvaged limb, irrespectively of patency of the re-construction, but was significantly higher after amputation. After PTA, only a reconstruction reported as patent was linked to the most favourable survival rate. The older patient group had a mortality rate of 6.4% at 1 month and 26.4% at 1 year, significantly higher than the younger group (3.8% and 17.6%, respectively). The amputation rate did not differ according to age. Significantly more patients were alive but not improved in the older group.

CONCLUSIONS

The outcome of surgery vs. PTA was similar regarding survival and amputation, but surgery resulted in a greater improvement although this might be due to selection. Older patients and those with an amputation had higher mortality rates.

Prevention of deep vein thrombosis in knee arthroplasty. Preliminary results from a randomized controlled study of low molecular weight heparin vs foot pump compression

BACKGROUND

We evaluated in a randomized controlled study the possibility to use foot pump mechanical compression compared to routine LMWH as prophylaxis against deep vein thrombosis during knee arthroplasty.

METHODS

Forty patients were included in this preliminary report. Eleven patients withdrew, usually during the early phase of the study.

RESULTS

Among the 29 patients completing a venography, 27% in the compression group and none in the LMWH group had a DVT. This difference was statistically significant (p<0.05). One further patient in the compression group died from pulmonary embolism 17 days postoperatively.

CONCLUSIONS

With the present study protocol, mechanical foot pump compression failed to be as efficient as LMWH prophylaxis.

Magnetic resonance imaging and MR angiography of endoluminally treated abdominal aortic aneurysms

OBJECTIVES

To evaluate magnetic resonance imaging (MRI) with gadolinium-based contrast medium-enhanced MR angiography (MRA) for the follow-up of endoluminally treated abdominal aortic aneurysms.

DESIGN

MRI/MRA, angiography and computed tomography (CT) were performed 1 month after endoluminal stent-graft placement. MRI/MRA was repeated at 6 and 12 months and angiography and CT were added to confirm unexpected findings.

MATERIALS

Fifteen male patients with endoluminally treated abdominal aortic aneurysms.

METHODS

MRI with MRA, spiral CT with transverse images and angiography were performed.

RESULTS

MRI/MRA demonstrated changes of stent-graft morphology, aortic neck- and aneurysmal diameter, stent-graft blood flow, stent-graft leakage, blood flow in lumbar arteries, intra-aneurysmal thrombus, periaortic inflammation and vertebral body infarction. For most of these features MRI/MRA provided more information than angiography and/or CT. MRI was the only method demonstrating thrombus reorganisation and vertebral body infarction.

CONCLUSIONS

MRI with MRA provides the relevant information needed for follow-up of endoluminally treated abdominal aortic aneurysms (AAA). This may be the method of choice because of its use of contrast media with very low nephrotoxicity, lack of ionising radiation and non-invasiveness.

[Endovascular technique in aortic aneurysm. A promising alternative to open surgery]

The article consists in a presentation of endovascular surgery for abdominal aortic aneurysm repair in 23 cases. Two cases required conversion to open surgery, but the procedure could be completed in the remaining 21 cases, with a current duration of follow-up of up to 30 months. There was early leakage in one case, and late leakage in five cases. Late conversion has been necessary in three instances, and supplementary endovascular measures have been required in a further two instances. All complications have occurred in those cases operated during the first half of the study period. Modification of the endoprosthesis used and increasing skill have reduced both operation time and the complication rate. Intensive care is no longer required, and the median duration of hospitalisation is three days. Follow-up with magnetic resonance imaging has yielded new and important information.

Venous thrombectomy for iliofemoral vein thrombosis--10-year results of a prospective randomised study

OBJECTIVES

To study if venous thrombectomy prevents late post-thrombotic sequelae, venous obstruction reflux, and improves venous physiology following an acute iliofemoral venous thrombosis.

DESIGN

Prospective randomised controlled study.

MATERIAL

Thirty patients returned for follow-up 10 years after an acute iliofemoral venous thrombosis initially treated with conventional anticoagulation treatment (medical group, n = 17) or with thrombectomy combined with a temporary arteriovenous fistula and anticoagulation (surgical group, n = 13). Clinical assessment, radionuclide angiography, duplex ultrasound and venous physiology tests were performed.

RESULTS

Leg swelling was recorded in 12 (71%) and leg ulcers in three (18%) of the medical patients and in, respectively, six (46%) and one (8%) of the surgical patients. The surgical patients had less severe sequelae (class 0-2). Radionuclide angiography demonstrated that the iliac vein was more commonly occluded following medical (59%) than following surgical (17%) treatment (p < 0.05). Duplex examination demonstrated slightly (n.s.) more reflux in the femoral and popliteal veins in the medical group. Venous physiology (occlusion plethysmography, foot volumetry, and foot vein pressures) did not show any significant differences, although the medical group tended to have a more severe pathology.

CONCLUSION

Venous thrombectomy improves venous patency and possibly reduces venous reflux and post-thrombotic sequelae as compared to anticoagulation treatment.