Biomedical subjects
A Marston
Publications and source records attributed to A Marston.
An immunohistochemical study of mesothelial cell seeding for knitted Dacron.
Six greyhounds underwent bilateral femoral artery replacement with knitted Dacron, one side seeded with omental digest at graft preclotting, the other acting as an unseeded control. Grafts were removed at 24 hours and two months. Tissue was examined using a monoclonal antibody (MNF116) directed against a broad range of human cytokeratins to differentiate mesothelial cells (MC) from microvascular endothelial cells (MEC), which stained only with a polyclonal antibody directed against von Willebrand Factor (anti-vWF). Cells released from omentum by collagenase stained with MNF116 and reacted poorly with anti-vWF. Identical cells were observed to be within the interstices of seeded but not control knitted Dacron. Few remained in seeded grafts (n = 2) removed at 24 hours and none at two months (n = 4).
Acute intestinal ischaemia.
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Intercollegiate surgical examinations.
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Chronic intestinal ischaemia.
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The provision of surgical services--the Royal College of Surgeons.
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Femorofemoral bypass in unilateral iliac artery occlusion.
Between January 1973 and January 1988, 188 patients with unilateral iliac artery occlusion were treated at The Middlesex and University College Hospitals, 185 for primary disease and three for blockage of a previous aortobifemoral graft. In the early part of the series, a variety of operations, including aortofemoral and iliofemoral bypass, and endarteriectomy, was used. Femorofemoral bypass was at first reserved for patients who were considered unfit for major surgery, but the results seemed so good that it was adopted as the procedure of choice. Latterly, percutaneous transluminal angioplasty became available, and the role of this is discussed. Over the 15-year period, 150 patients underwent femorofemoral bypass (all but two receiving a prosthetic graft). Of these, 90 per cent had disabling claudication and 8 per cent had critical ischaemia. There were six early deaths (within 30 days of operation) and five late deaths, and two surviving amputees; nine patients could not be traced. The remaining 128 patients have been assessed at intervals of from 3 to 92 months, both clinically and with Doppler studies. The cumulative patency was 86 per cent at 13 years, and all of these patients experienced subjective and haemodynamic improvement in the recipient limb. Eight grafts occluded in the early postoperative phase. In five patients there was deterioration in the donor limb; it is postulated that the effect was due to causes other than the operation. There were two serious postoperative complications due to technical error, one of which led to early above-knee amputation. These are presented in detail. In the light of this experience, the advantages and indications for femorofemoral bypass and the results to be expected from it have become clarified, and the technique standardized so that errors can be avoided. We suggest that femorofemoral bypass is now the operation of choice for unilateral iliac artery occlusion.
Treatment of cancer of the colon: a non-specialist's point of view.
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Laser angioplasty with a pulsed NdYAG laser: early clinical experience.
Since December 1986, 40 laser angioplasty procedures have been performed using the energy from a pulsed NdYAG laser, delivering near infrared light (1064 nm) in 100-microseconds pulses of approximately 300 mJ per pulse, directly through a transparent sapphire tipped device. All patients had total occlusion of the superficial femoral artery and symptoms severe enough to warrant surgery, with ulceration or gangrene in eight, rest pain in 14 and severe claudication interfering with life-style in the others. The device was introduced through an antegrade puncture of the superficial or common femoral artery and laser recanalization was followed by attempted balloon angioplasty in all cases. Occlusions were a median length of 15 cm (range 2-35 cm); ten patients had previously undergone failed attempts at conventional balloon angioplasty and four had occluded femoropopliteal grafts. Thirty-seven legs of 34 patients were treated with an average of 60 J (range 10-235 J) with successful recanalization in 27 and immediate reocclusion in seven. The 20 successful recanalizations have been followed up for up to 24 months (median 7 months) with only one late occlusion at 5 months. Failed recanalization was due to poor transmission by the delivery device in the early part of the series (five cases), repeated passage of the device down a collateral branch (four cases), dissection at the site of previous surgery (two cases) or no apparent reason (two cases). Immediate reocclusion was due to very poor run off in patients with severely ischaemic limbs (three cases) or technical difficulties with balloon dilatation (two cases). Complete symptomatic relief was obtained in all the cases of radiologically successful laser angioplasty. Early surgery was required in one case following reocclusion of the artery when an angioplasty balloon failed to deflate, and one patient suffered a skin reaction thought to be due to inadequate removal of the sterilizing solution. A different sterilizing procedure is now followed. Laser angioplasty can reduce the number of patients requiring bypass surgery and improvements in the device and access methods may reduce the number of untreatable cases.
Assessment of a new device for laser angioplasty.
Experimental work has shown that a transparent laser device delivering pulsed energy to an artery results in a smaller area of surrounding damage than does an opaque device with a continuous wave laser. The combination of a transparent ball-tipped device with a pulsed Nd-YAG laser has been investigated. The system delivers pulses of 100 microseconds at a rate of 10 Hz and average energy of 0.5 J per pulse with an energy loss of 5-10% between the output at the laser rail and the fibre tip. The dose/response was measured and showed that on normal aorta under saline the device produces craters with a depth of 5 microns/J and 1.5 mm radius. There is a 100% increase in dose response with diseased aorta and a 50% increase when exposure is carried out under blood. The effect of a varying angle of incidence upon the arterial wall has been measured. Angulation of the device at 10 degrees from the perpendicular reduces the crater depth to 50%, as compared with a 50% reduction at 60 degrees using a bare fibre. As estimated with a thermal camera in air, the device heats up to a maximum of 50 degrees C during a 50 J exposure, compared to 110 degrees C after 5 J for the sapphire device. Artificial circulation experiments were carried out using diseased femoral vessels occluded by a ligature. The new system recanalised 100% of occlusion in straight vessels, and 40% of occlusions in curved vessels at a radius of 2.5 cm.(ABSTRACT TRUNCATED AT 250 WORDS)
Management of the ischaemic leg. The modern approach.
Atheroma leading to blockage of the leg arteries is on the increase, throughout the world. Its commonest manifestation is intermittent claudication, a symptom which usually improves without treatment, provided that the patient takes regular exercise and does not smoke. It follows, that claudication on its own does not usually need further investigation. If the patient deteriorates, or develops rest-pain, then some form of arterial reconstruction will be required, and at this point an arteriogram becomes necessary, in order to decide the best method. Available techniques include endarterectomy, balloon and laser angioplasty, and bypass surgery, and the respective roles of these are discussed. If surgery becomes necessary, the best bypass is the patient's own long saphenous vein. In the event of this not being available, a synthetic tube is used. There is nothing to suggest that the more expensive synthetics have any advantage over the cheaper ones.
Effects of autologous mesothelial cell seeding on prostacyclin production within Dacron arterial prostheses.
Canine abdominal aortas have been replaced with Dacron arterial prostheses to assess the effects of mesothelial cell seeding on graft prostacyclin and thromboxane A2 release. At both 2 weeks and 6 weeks after surgery, three seeded and two unseeded control grafts were examined for prostacyclin release. In addition, thromboxane release was assessed in one seeded and one unseeded graft. Sections of aorta and graft were removed and incubated in PBS containing either 10 microM calcium ionophore A23187 or 20 microM arachidonic acid. The incubation mixture was sub-sampled at 5 min intervals over a 20 min period to assess the progressive release of prostacyclin and thromboxane A2 using a radioimmunoassay for 6-keto-prostaglandin F1 alpha and thromboxane B2 respectively. In seeded grafts, 6-keto-prostaglandin F1 alpha release averaged 15 per cent compared with aorta at 2 weeks and 45 per cent compared with aorta at 6 weeks. By contrast, release from unseeded grafts was undetectable at 2 weeks; however, by 6 weeks there was some release amounting to 15 per cent compared with aorta. There was a statistically significant increase in the release of 6-keto-prostaglandin F1 alpha from mesothelial cell seeded grafts at 6 weeks compared with unseeded grafts (P less than 0.01). Thromboxane release from the graft sections was variable and unrelated to whether the grafts had been seeded or not. These preliminary results, showing that grafts seeded with autologous peritoneal mesothelial cells release more prostacyclin than unseeded grafts, further highlight the role of the mesothelial cell as an alternative to the endothelial cell for improving the patency of arterial Dacron prostheses in the early postoperative days.
Vascular assessment before amputation.
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A 5 year follow-up of Dacron femoropopliteal bypass grafts.
Over a 5 1/2 year period, 66 Dacron femoropopliteal grafts were performed for patients with an absent or unsuitable long saphenous vein. The minimum follow-up has been 6 months and cumulative patency was 50 per cent at 5 years. Twenty-five patients had critical ischaemia (preoperative Doppler ankle pressure less than 40 mmHg) and 41 patients had severe ischaemia (pre-operative ankle pressure greater than 40 mmHg). The procedure significantly improved ankle pressures in both groups and this was maintained at follow-up. In the group of 25 patients with critical ischaemia there were three operative deaths and in 10 the graft subsequently occluded, precipitating an amputation. In the group of forty-one patients with severe ischaemia, there was one operative death and in two patients the graft occluded at 18 and 24 months. In this small series there was no significant difference in patency, whether the graft was placed to the popliteal artery above or below the knee joint, or whether the popliteal had less than three patent branches at its trifurcation.
Mesenteric infarction. Invited commentary.
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Blood pressure changes in the marginal artery of the colon following occlusion of the inferior mesenteric artery.
The perfusion pressure in the marginal artery of the descending colon was measured continuously at laparotomy in eight patients and the effect of sudden occlusion of the inferior mesenteric artery recorded. Three patients with ulcerative colitis, all in their early 30s, and five elderly patients with colonic or rectal carcinoma were studied. In all patients occlusion caused an initial and marked pressure drop, which remained reduced at a critically low level in two of the elderly patients. Such a reduction in perfusion pressure is probably still insufficient to interfere with the nourishment of the terminal part of the colon provided that the systemic pressure is kept at a normal level. However, since in many patients there is a sharp drop in systemic blood pressure during the recovery phase after surgery, it appears likely that the perfusion pressure in the marginal artery may in those cases be insufficient to maintain an adequate blood flow to the colon despite the inherent tendency of "auto-regulation" in this vascular bed. The results of the present study indicate that, contrary to previous belief, ligation of the inferior mesenteric artery may increase the risk of ischaemia in the terminal part of the descending colon, leading to anastomotic dehiscence after anterior resection, or sloughing after a "pull-through" operation. This complication could probably be prevented by a more generous resection of the sigmoid and descending colon, thus reducing the length of the anastomosis formed by the arc of Riolan and by careful maintenance of an adequate blood pressure during the recovery phase.