N.J.M. London

Subintimal angioplasty of femoropopliteal artery occlusions: The long-term results*

The technique of subintimal angioplasty has been attempted on 200 consecutive femoropopliteal artery occlusions of median (range) length 11 (2-37) cm. The principle of the technique is to traverse the occlusion in the subintimal plane and recanalise by inflating the angioplasty balloon within the subintimal space. The technical success rate was 159/200 (80%) and was not significantly different for occlusions < 10 cm (81%, n = 73), 11-20 cm (83%, n = 63) or > 20 cm (68%, n = 23), p = 0.20. There were no deaths nor limb loss resulting from the procedure. The median (range) ankle-brachial pressure index increased from 0.61 (0.21-1.0) preangioplasty to 0.90 (0.26-1.50) postangioplasty. The actuarial haemodynamic patencies of technically successful procedures at 12 and 36 months were 71% and 58% respectively, the symptomatic patencies were 73% and 61%. A multiple regression analysis showed that smoking multiplied the risk of reocclusion by 2.70 (p < 0.001), each additional run-off vessel reduced the risk by 0.54 (p < 0.001) and the risk increased by 1.73 (p = 0.020) for every 10 cm of occlusion length. In conclusion, the technical success rate (80%) of subintimal angioplasty for femoropopliteal occlusions is unrelated to occlusion length and for all procedures, including technical failures, cumulative symptomatic and haemodynamic patencies of 46 and 48% can be achieved at 3 years. The factors influencing long-term patency were smoking, the number of calf run-off vessels and occlusion length.

The effect of capsule composition on the biocompatibility of alginate-poly-l-lysine capsules

The encapsulation of islets of Langerhans in alginate-poly-l-lysine has been proposed as a method for the immunoprotection of transplanted islets. Although several capsule compositions have been reported, there has been no published study concerning the effect of capsule composition on the severity of the foreign body reaction. Empty capsules were prepared from high mannuronic acid alginate and were coated with: (1) poly-l-lysine alone, (2) poly-l-lysine plus high guluronic acid alginate, or (3) poly-l-lysine plus high mannuronic acid alginate. The capsules were placed in the renal subcapsular space or the peritoneal cavity, and retrieved after three weeks of histological examination. The recipients were WAG/01a, nude (athymic), diabetic BB, and non-diabetes prone BB rats. The severity of reaction to the capsules was determined by measuring the thickness of the pericapsular cell infiltrate or by a scoring system. The severity of the reaction to the capsules was strain-dependent in both the renal and peritoneal sites, with the BB and nude rats displaying the most severe responses. The degree of response was not affected by capsule composition in the renal subcapsular space, but in the peritoneum, the high mannuronic acid alginate capsules provoked the weakest response, and this type of capsule will be used for future transplantation work. The infiltrating cells were characterised by immunohistochemistry and electron microscopy and found to be mostly fibroblasts and macrophages.

SUBINTIMAL ANGIOPLASTY OF INFRAPOPLITEAL OCCLUSIONS IN CRITICALLY ISCHAEMIC LIMBS

OBJECTIVE To review the outcome of subintimal angioplasty of infrapopliteal artery occlusions in critically ischaemic limbs. DESIGN Retrospective review. MATERIALS Twenty-eight consecutive limbs with critical ischaemia that had undergone subintimal angioplasty of infrapopliteal occlusions. RESULTS There were 32 infrapopliteal artery occlusions in 28 critically ischaemic limbs in 27 patients. The median (range) patient age was 81 (48-88) years. Seventeen limbs (61%) were ulcerated, seven (25%) were gangrenous and four (14%) had rest pain only. Twenty-five (89%) procedures were to a single calf vessel, and three (11%) procedures were to multiple calf vessels. The median (range) length of the occlusions was 7 (2-30) cm. The initial technical success rate was 27/32 (84%). There were three minor complications--one groin haematoma, one vessel perforation and one distal embolus. There were no limbs lost as a result of the procedure itself and the 30-day mortality was zero. The 12-month actuarial haemodynamic and symptomatic patencies (including initial failures) were 53% and 56%, respectively. The 12-month limb salvage rate was 85% and patient survival was 81%. CONCLUSION We conclude that subintimal angioplasty in patients with infrapopliteal artery occlusions and critical ischaemia is safe, effective, and offers a low-risk alternative to distal reconstructive surgery.

Chronic critical leg ischaemia must be redefined.

The Second European Consensus Document on Chronic Critical Leg Ischaemia defines critical limb ischaemia in non-diabetic patients as rest pain or tissue necrosis (ulceration or gangrene) with an ankle systolic pressure (ASP) of less than or equal to 50 mmHg, or a toe pressure of less than or equal to 30 mmHg. The aim of this study was to investigate whether this definition is able to predict the outcome of patients with severe lower limb ischaemia and thus to determine the relevance of the definition in clinical practice. We have analysed 148 severely ischaemic limbs in 133 non-diabetic patients who presented with rest pain, tissue necrosis or a combination of these symptoms. Fifty-one percent of these limbs fulfilled the current definition with an ASP < or = 50 mmHg; 49% had an ASP > 50 mmHg and were thus not defined as critically ischaemic according to the current definition. We have compared actuarial limb salvage and mortality rates in patients with an ASP < or = 50 mmHg to those patients with an ASP > 50 mmHg. The 1 year limb salvage and mortality rates for ischaemic limbs fulfilling the European Consensus Document criteria were 78.7 and 36.7% respectively, compared to rates of 73.9 and 17.3% in patients who were not defined as critically ischaemic under the current definition. There were no significant differences between 1 year limb salvage or mortality rates between the two patients groups (p = 0.843, 0.078, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Infrapoliteal percutaneous transluminal angioplasty: A safe and successful procedure

AIM To review outcome of 40 consecutive infrapopliteal percutaneous transluminal angioplasty (PTA) procedures performed over a 65 month period. CHIEF OUTCOME MEASURES The indication for PTA was intermittent claudication in 20 (50%) cases and rest pain, ulceration or gangrene in the remainder. RESULTS There was one technical failure; the remaining 39 limbs were all clinically improved by 24 h and this improvement was maintained at 3 months in 36 (90%). There were no deaths nor limb loss related to PTA and 2 embolic complications were successfully treated percutaneously. The primary and secondary symptomatic patencies at 24 months were 59 and 79% respectively. The actuarial limb salvage rate at 1 year for the 20 limbs presenting with critical ischaemia was 77%, and 10 of the 14 procedures performed for ulceration or gangrene resulted in healing with only minor surgical intervention. CONCLUSIONS With modern endovascular techniques, infrapopliteal PTA is a safe, worthwhile and durable procedure.

Selection of Patients with Critical Limb Ischaemia for Femorodistal Vein Bypass

The merits of an aggressive policy of distal reconstruction have been questioned by some observers. To determine the factors affecting graft patency and mortality, we analysed 78 consecutive infragenicular femorodistal vein grafts performed in 72 patients with critical limb ischaemia. The primary, primary assisted and secondary graft patency rates at 36 months were 29, 57 and 64%, respectively. The limb salvage and patient survival rates at 36 months were 67 and 74%, respectively. Univariate analysis (log-rank test) was performed to identify factors affecting graft patency, limb salvage and mortality at 1 month (perioperative) and 1 year. Independent variables of age, sex, diabetes, presentation, level of anastomosis and vein technique (reversed or in situ) did not affect graft patency. The ankle systolic pressure did not predict graft patency but was an independent variable affecting mortality (p = 0.047), as did diabetes (p = 0.019). These results show that excellent limb salvage can be successfully achieved in severely ischaemic patients by adopting an aggressive approach to femorodistal bypass, and that age, gender and poor medical condition are not contraindications to femorodistal bypass. The difference between the primary and primary assisted patency rates in this series is dramatic and reflects the impact of a vein graft surveillance programme in preventing graft occlusion.

Patients' ability to recall risk associated with treatment options

Many practitioners have expressed concern about patients’ ability to understand and recall information about the risk associated with treatment options. A search of medical articles however has revealed very little systematic research in this area. We report a systematic study that analysed patients’ recall of the risks related to carotid endarterectomy (CEA). CEA is a prophylactic surgical procedure that is done to reduce the chance of embolic stroke. The risks associated with surgery and best medical treatment are well understood for this patient group. The operation will reduce but not abolish the risk of stroke, and in a small proportion of patients it will cause a stroke. The operation has an associated stroke risk of 5–7%. Patients who are suitable for surgery were all counselled in the clinic by a consultant in the same manner. Patients were informed that their chance of suffering a stroke in the next three years if they didn’t have the operation was approximately 22%. The risk of suffering a perioperative stroke as a result of CEA was also highlighted. At our own hospital this risk is 2·3%, which was determined from an audit of our last 450 CEAs. 71 patients on the waiting list for CEA were sent a quetionnaire 1 month after their clinic appointment (56 responded). This questionnaire was designed to assess patients’ understanding of the risks associated with the different treatment alternatives. Patients were asked to recall their risk of suffering a stroke with each of the treatment options. Patients consistently failed to recall their risk of stroke. Most patients remembered if they proceeded with surgery then their longterm risk of stroke would be reduced. However, over 10% of patients thought that their risk of suffering a stroke at the time of CEA was at least 50%. More worrying was the finding that some patients thought that there was no risk of stroke associated CEA and 11% of patients simply did not know. Only one patient was able to quote the risks that he was told. Patients’ responses are summarised in the table. This study suggests that either patients have very little understanding of the risks and benefits associated with a prophylactic procedure (CEA) or they quickly forget them. One of the main findings of the recent enquiry by the General Medical Council into the conduct of the Bristol heart surgeons was that parents were misinformed about the risk associated with surgery. In the Bristol scenario many months or years after the consultation, parents testified that they were unable to recall accurately the risks associated with paediatric cardiac surgery. Although the present study examines a different operation and patient cohort, it seems fairly clear that patients’ recall of statistical data related to risk is limited, even in the short term. Our survey suggests that informed consent based on verbal information alone is not enough, and that an information letter should be given to each patient as a part of the process of informed consent.

A prospective comparison of lower limb colour-coded duplex scanning with arteriography

OBJECTIVE To compare the diagnostic value of colour Duplex scanning with arteriography for the detection of arterial disease of the aortoiliac arteries, femoropopliteal arteries and the origins of the tibial vessels. DESIGN Prospective, semi-blind study. SETTING Vascular laboratory and radiology department, University Hospital. METHODS A total of 1658 arterial segments in 148 limbs were studied both by colour Duplex scanning and digital subtraction arteriography. Individual arterial segments were classified on the basis of peak systolic velocity ratios < 2.0, > or = 2.0 or an absent Doppler signal, as 0-49%, 50-99% diameter reduced, or occluded. The same arterial segments were similarly classified on the basis of arteriography and the two modalities were compared using a Kappa (k) analysis. RESULTS The overall agreement between arteriography and colour-coded Duplex was kappa = 0.74 (95% CI, 0.70-0.78), this indicates substantial agreement. Kappa values (95% CI) from the aortoiliac, femoropopliteal and the origins of the infrapopliteal arteries were kappa = 0.59 (0.49-0.73; moderate agreement), kappa = 0.80 (0.76-0.84; substantial agreement) and kappa = 0.48 (0.35-0.61; moderate agreement) respectively. CONCLUSIONS We conclude that there is substantial agreement between colour-coded Duplex and arteriography of the lower limbs, and that the ability of colour-coded Duplex to plan and guide lower limb vascular interventions requires investigation.

The optimization of large-scale density gradient isolation of human islets.

The use of the COBE 2991 cell processor (COBE Laboratories, Colorado) for large-scale islet purification using discontinuous density gradients has been widely adopted. It minimizes many of the problems such as wall effects, normally encountered during centrifugation, and avoids the vortexing at interfaces that occurs during acceleration and deceleration by allowing the gradient to be formed and the islet-containing interface to be collected while continuing to spin. We have produced cross-sectional profiles of the 2991 bag during spinning which allow the area of interfaces in such step gradients to be calculated. This allows the volumes of the gradient media layers loaded on the machine to be adjusted in order to mazimize the area of the gradient interfaces. However, even using the maximal areas possible (144.5 cm2), clogging of tissue at such interfaces limits the volume of digest which can be separated on one gradient to 15 ml. We have shown that a linear continuous density gradient can be produced within the 2991 bag, that allows as much as 40 ml of digest to be successfully purified. Such a system combines the intrinsic advantages of the 2991 with those of continuous density gradients and provides the optimal method for density-dependent islet purification.

A comparison between colour duplex ultrasonography and arteriography for imaging infrapopliteal arterial lesions

OBJECTIVE To investigate the agreement between colour duplex ultrasonography and digital subtraction arteriography of the infrapopliteal arteries. DESIGN Retrospective, blinded study. SETTING Vascular laboratory and Radiology Department, University Hospital. METHODS The infrapopliteal vasculature was examined in a total of 51 limbs by both colour duplex ultrasound and digital subtraction angiography. By examining all arteries from the distal popliteal to the pedal arteries, a total of 204 individual arterial segments were available for analysis. Each segment was graded as 0-49%, 50-99% diameter reduced or occluded by both modalities. Using ultrasound, classification of stenoses was achieved by observing peak systolic velocity ratios; a doubling of peak systolic velocity indicating a > or = 50% diameter reducing stenosis. Where no Doppler signal could be obtained, the vessel was assumed to be occluded. From angiographic studies, two radiologists separately and blindly assessed the extent of disease for each infrapopliteal artery noting areas of > or = 50% diameter reduction and occlusion. The Kappa statistic was used to examine the level of agreement between angiography and ultrasound as well as between both radiologists. RESULTS The Kappa level (95% confidence interval) of agreement between ultrasound and angiographic assessments for distinguishing patent from occluded segments was 0.61 (0.49-0.74) for all segments. The equivalent agreement between radiologists was 0.80 (0.70-0.89). Poorest agreement was observed from ultrasound assessments of the peroneal and tibioperoneal trunk arterial segments. CONCLUSION Since agreement between colour duplex scanning and angiography never fell significantly below levels achieved between two radiologists, we conclude that colour duplex ultrasound can be used to assess infrapopliteal artery patency.