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Biomedical subjects

A M Graham

Publications and source records attributed to A M Graham.

At least 55 records · Page 3Linked to original sources
PubMed1990

Comparison of in-situ and reversed saphenous vein grafts for infrageniculate bypass.

Current controversy surrounding in-situ and reversed saphenous vein grafts prompted a review of 161 procedures performed between 1982 and 1987. Analysis was based on objective criteria recommended by the Society for Vascular Surgery/International Society for Cardiovascular Surgery (SVS/ISCVS) Committee on Reporting Standards. There were 92 in-situ bypasses, 42 to the popliteal artery below the knee, and 50 to tibial vessels; of 69 reversed vein grafts, the comparable figures were 51 and 18. Sixty-seven in-situ and 43 reversed grafts were done for foot salvage. The overall primary patency rate for in-situ grafts was 81.1% at 30 days, 77.0% at 1 year, 74.7% at 3 years and 59.8% at 5 years; corresponding reversed vein patency rates were 85.2%, 76.8%, 67.0% and 42.3%. Patency rates for foot salvage for in-situ grafts were 81.7% at 1 month, 75.9% at 1 year and 72.6% at 3 years, and for reversed vein grafts 78.6%, 70.3% and 66.5%. Secondary patency rates were 72.8% at 3 years for in-situ vein and 67.2% for reversed vein; the foot-salvage rate at 3 years was 91.0% with in-situ vein and 78.9% with reversed vein. The study demonstrated no statistically significant difference between in-situ and reversed saphenous vein bypass for infrageniculate reconstruction, regardless of the distal anastomotic site or severity of disease. Although a trend favouring the in-situ technique was noted, particularly at the tibial level, longer follow-up and a prospective randomized trial is needed to evaluate this.

Aged↗
PubMed1989

An histo-morphological evaluation of ninety surgically excised human umbilical vein grafts.

Morphological, histological, and scanning electron microscopy examinations were performed on 90 surgically excised human umbilical vein grafts. Most of the explanted grafts were removed because of thrombosis or infection and were removed typically from a patient in the mid 60s and after an average duration of implantation of 11 months. Multiple structural defects were found including deep folds, breaks on the luminal surface, and delamination. These areas as well as anastomotic sites represented potential areas for thrombotic accumulation. A higher incidence of infection was observed in grafts composed of 2 or 3 segments. Bacteria were often found in folds and could be seen invading the wall of the prosthesis. In addition, bacteremic colonization was often seen in noninfected grafts. The late aneurysmal formations were also of particular concern. The biodegradation of the wall and the disruption of the polyester mesh were the probable causes. The second generation Dardik Biograft aimed at reducing these formations. The success of this new processing remains to be evaluated.

Adult↗
PubMed1989

A demonstration of vascular proliferation in response to arteriovenous reversal in the ischemic canine hind limb.

Patients with diffuse peripheral vascular disease, resulting in inadequate arteriographic runoff, and/or multiple failed bypasses almost inevitably face amputation. We have previously used an arteriovenous reversal (AVR) procedure at the popliteal level to salvage severely ischemic canine hind limbs. This procedure is followed by the development of an intense network of new vessels in the proximity of the arteriovenous anastomosis. The present study was designed to define the nature of these vessels and their role in providing nutrient perfusion to the limb. Using an established model to create severe limb ischemia. AVR was performed in 24 dogs. Tissue perfusion and neovascularization were assessed by angiography, transcutaneous oximetry (TcpO2), tritiated thymidine uptake combined with autoradiography, and histologic capillary density measurements. Angiography revealed the intense vascular network in the region of the anastomosis by postoperative Day 22 in all dogs. TcpO2 on Day 1 was indicative of severe ischemia in the operated calf compared to controls (12 vs 80 mm Hg, P less than 0.01) but returned to normal by Day 22 (81 vs 76 mm Hg). A progressive, significant increase in tritiated thymidine uptake was seen by Day 22 (0.36 vs 0.27 microCi/g, P = 0.005); on autoradiography 95% of these labeled nuclei in the operated limbs were in endothelial cells compared to only 5% in the control limbs. Finally, capillary density studies of the calf muscles showed a substantial increase in the operated limbs (mean, 1011 vs 605 cap/mm2, P = 0.0004). These studies suggest that the dramatic increase in vascularity observed angiographically following AVR in a severely ischemic limb consists primarily of a rapidly expanding capillary network.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Haem biosynthesis in the unconjugated hyperbilirubinaemias: observations in the Gunn rat model.

Disturbances of the enzymes of haem biosynthesis have been reported in patients with unconjugated hyperbilirubinaemia. We have examined the excretion of haem precursors in the Gunn rat which suffers from severe unconjugated hyperbilirubinaemia. In urine, levels of aminolaevulinic acid and total porphyrin were significantly reduced when compared to controls. In feces both coproporphyrin and protoporphyrin levels were reduced in Gunn rats, the former being more affected. Blood porphyrin levels in control and Gunn rats were similar.

Aminolevulinic Acid↗
PubMed1989

Are free radical scavengers beneficial in the treatment of compartment syndrome after acute arterial ischemia?

Because it is postulated that compartment syndrome developing secondary to an acute arterial occlusion may be due to reperfusion injury, oxygen-derived free radicals have been implicated in its genesis. To assess the possible beneficial effect of free radical scavengers in this setting, we used a previously established in vivo canine model of compartment syndrome to compare four groups: group I, no treatment; group II, prophylactic fasciotomy; group III, intravenous albumin conjugated superoxide dismutase (SOD); group IV, intravenous mannitol (hydroxyl radical scavenger). Both hind limbs were completely devascularized at the popliteal level except for an isolated pedicle to the anterior compartment. The right limb served as the nonischemic control, whereas the left underwent 8 hours of ischemia followed by reperfusion. Continuous monitoring of transfascial oxygen tension (tfPO2) demonstrated severe ischemia during occlusion (tfPO2 5.7 +/- 5.1 mm Hg) and restoration of blood flow with reperfusion (mean tfPO2 50 to 60 mm Hg). Measurements of compartment pressure were significantly higher after reperfusion in groups I, III, and IV when compared with those of group II (p less than 0.001, groups I and II; p less than 0.01, group IV). Extent of muscle necrosis assessed by technetium pyrophosphate scanning and expressed as a ratio of left to right legs was as follows: group I, 8.9 +/- 5.0; group II, 2.6 +/- 0.5; group III, 2.8 +/- 0.8; group IV, 1.8 +/- 0.6. Muscle contraction studies 16 hours after reperfusion indicated abnormal findings in all but group II. In conclusion, administration of free radical scavengers did not preserve normal neuromuscular function despite a significant reduction in muscle damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Evaluation of autotransfusion in elective aortic reconstruction.

A new intraoperative autotransfusion system was prospectively evaluated in 30 major aortic reconstructions. After systemic heparinization of the patient, blood is collected in a cardiotomy reservoir and immediately reinfused (up to 500 ml/min). The amount of autotransfused or banked blood necessary to maintain the hemoglobin at 100 g/L during and for 24 hours after surgery was monitored and coagulation profiles, renal function and complications were recorded. The amount of autotransfused blood averaged 1414 ml and the number of packed red blood cells transfused over 24 hours averaged 1.9 units. Of the 30 patients, 24 required 2 units of homologous blood or less over 24 hours; 8 patients received no homologous transfusions and another 8 only 1 unit. There was no significant change postoperatively in serum creatinine or fibrinogen levels or in the prothrombin and partial thromboplastin times; the platelet count fell from 264 x 10(9)/L preoperatively to 182 x 10(9)/L postoperatively (p less than 0.05), but this was not clinically relevant. The free plasma hemoglobin level rose substantially, but perioperative urine output was good. There were no complications attributable to autotransfusion. The use of the autotransfuser during major vascular surgery provides a safe, effective means to minimize the loss of clotting factors, preserve blood-bank resources and eliminate the risk of disease transmission from homologous blood. By allowing rapid reinfusion when blood loss is excessive, this system can prevent prolonged hypotension in patients at increased cardiac risk.

Aortic Diseases↗
PubMed1989

Internal carotid artery aneurysm and Marfan's syndrome.

Aneurysms of the extracranial carotid artery are most commonly caused by atherosclerosis or trauma but may also have unusual causes, such as Marfan's syndrome. Although aneurysmal changes in the extracranial carotid vessels usually are due to extension of aortic dissection into the carotid system, isolated aneurysms may occasionally complicate Marfan's syndrome. The authors report a case of Marfan's syndrome in which the patient, a 45-year-old woman, presented with an asymptomatic mass in the right side of the neck at the level of the carotid bifurcation. An isolated internal carotid artery aneurysm was identified. The aneurysm was resected using an interposition vein graft over an outlying shunt. Histologic examination confirmed the typical cystic medial necrosis with loss of elastic fibres and an increase of mucoid material in the media. The patient's recovery was smooth and at 2-year follow-up there were no signs of recurrent aneurysm formation.

Aneurysm↗
PubMed1988

Coagulopathy induced by aortoiliac aneurysms.

Diffuse intravascular coagulopathy (DIC) or consumptive coagulopathy is infrequently associated with aortic aneurysms. When the two coexist, they create a difficult clinical problem that requires optimal medical and surgical care. Two cases of coagulopathy associated with aortoiliac aneurysm are presented to exemplify the broad clinical picture that can be present. The definitive treatment of DIC is removal of the underlying cause. The following recommendations are made for the management of patients with aortic aneurysms and possible coagulopathy: preoperatively examine the patient for hematomas and ecchymoses; measure levels of fibrinogen, platelets and fibrin degradation products and the prothrombin and partial thromboplastin times; perform arteriography and check puncture sites for spontaneous bleeding afterwards; at aneurysm repair ensure meticulous hemostasis and compensate for excessive blood loss by high-speed autotransfusion.

Aged↗
PubMed1986

Predicting cerebral ischemia during carotid endarterectomy.

We reviewed 86 consecutive patients undergoing elective carotid endarterectomy to determine whether preoperative clinical and angiographic data could be used to predict the risk of intraoperative cerebral ischemia during carotid occlusion. Electroencephalographic (EEG) monitoring with on-line Berg-Fourier transformation was carried out in all patients. A total of 32 patients (37.2%) underwent intraoperative shunting. Of these, 13 had no EEG changes but underwent shunting because of the surgeon's preference, while 19 patients underwent shunting because of EEG changes consistent with cerebral ischemia. There was one permanent (1.2%) and one transient (1.2%) neurologic deficit. Angiographic findings, clinical histories, and intraoperative EEGs were retrospectively reviewed to determine which risk factors best predicted the occurrence of intraoperative cerebral ischemia. Stroke within six weeks increased the risk of intraoperative cerebral ischemia 20-fold. Intracranial disease and contralateral carotid stenosis increased the risk of ischemia 17-fold and 16-fold, respectively. Statistical summation of all risk factors yielded a probability equation for EEG change that accurately quantitated pre-operative risk. Prospective application of this probability equation may simplify operative decision making if EEG monitoring is not available.

Aged↗
PubMed1986

Spectral analysis of EEG during carotid endarterectomy.

Spectral analysis of the electroencephalogram (EEG) was monitored during 105 carotid endarterectomies. Seventy-eight percent of the patients showed no significant change in EEG spectral power as a result of clamping of the internal carotid artery. Two patterns of change were observed in the remaining 22% of patients: partial reduction (significant decrease of power in one or two of three frequency bands) and global reduction (significant decrease of power in all three frequency bands). High frequencies (over 10.5 Hz) changed more frequently with clamping than did low frequencies (less than 6 Hz), but reduction of high frequencies alone was tolerated with no postoperative deficits. The only non-shunted patient demonstrating global EEG reduction for the duration of carotid clamping suffered a transient hemiparesis.

Aged↗
PubMed1986

Parathyroid exploration for primary hyperparathyroidism.

Parathyroidectomy was studied retrospectively in 107 patients with primary hyperparathyroidism. This condition was diagnosed by measuring both the total serum calcium and ultrafilterable calcium (non-protein-bound) levels. The identification of ultrafilterable calcium is an important adjunct to parathyroid surgery as it allows the diagnosis of hyperparathyroidism when the total serum calcium level is normal. The surgical technique for selective parathyroidectomy and multiple biopsies was uniform. Parathyroid adenoma was discovered in 73 patients, diffuse hyperplasia in 26 and combined disease in 8. Postoperatively, two patients suffered from permanent hypocalcemia and three had hypercalcemia.

Adenoma↗
PubMed1986

Efficacy of isolated profundaplasty.

Profundaplasty has been advocated as an outflow procedure for threatened failure of aortobifemoral grafts as well as a primary procedure for severe claudication and limb ischemia. The authors reviewed their experience with 27 patients who underwent profundaplasty between 1978 and 1983; five patients (group 1) were treated for threatened or complete aortofemoral graft thrombosis while 22 patients (group 2) underwent profundaplasty as an isolated procedure to treat limb ischemia. Preoperative angiograms were assessed for the presence of five criteria associated with a favourable result from profundaplasty: stenosis of the orifice of the deep femoral artery greater than 50%; minimal disease of the distal artery; disease-free collaterals; reconstitution of a patent superficial femoral or popliteal artery; good popliteal outflow with at least one vessel patent to the foot. Profundaplasty was successful in 100% of group 1 patients but relieved symptoms or healed lesions in only 14% of those in group 2. In the latter group 64% required major amputation. The number of favourable angiographic criteria was similar in both groups. Isolated profundaplasty for limb salvage is not recommended. Angiographic criteria do not reliably identify the few patients who will benefit from profundaplasty alone. The principal role of the procedure is increasing outflow for an aortic graft.

Aged↗
PubMed1984

Mesenteric desmoid tumor in Gardner's syndrome treated by sulindac.

Mesenteric desmoid tumors are a recognized sequela of colectomy for polyposis coli of Gardner's type. Relentless growth and recurrence carry a poor prognosis. Recently, nonsteroidal anti-inflammatory drugs have been used to halt the growth of these tumors, presumably by interfering with prostaglandin metabolism. A 36-year-old man presented with small-bowel obstruction secondary to a large, diffuse mesenteric desmoid six years following colectomy and ileoproctostomy. Laparotomy revealed it to be unresectable. Postoperatively, he was started on sulindac (Clinoril) 100 mg twice a day. His obstruction resolved, and he remains well at 11 months. A CT scan shows diminution in the size of the tumor. Nonsteroidal anti-inflammatory agents may be an alternative to chemotherapy and radiotherapy in treating mesenteric desmoids.

Adult↗
PubMed1984

Salvage of a severely ischemic limb by arteriovenous revascularization: a case report.

Severe ischemia in a limb that cannot be revascularized almost inevitably leads to gangrene and eventual amputation. For decades, surgeons have considered utilizing the venous system to revascularize ischemic tissue in numerous areas, including the lower limb, but with very limited success. This report documents the successful revascularization of a severely ischemic pregangrenous limb with a bypass graft from the femoral artery to a tibial vein. The authors believe this is the first clinical report of salvage of an ischemic limb by this approach.

Aged↗
PubMed1984

Doppler waveform analysis versus segmental pressure and pulse-volume recording: assessment of occlusive disease in the lower extremity.

In a prospective study, the accuracy of combined segmental pressure measurements and pulse-volume recordings was compared with Doppler waveform analysis in evaluating peripheral arterial occlusive disease. Before arteriography, 50 patients (100 limbs) underwent vascular assessment which included measurement of the segmental pressure and pulse volume at the thigh, calf and ankle. Analogue Doppler waveform tracings were obtained from the femoral, popliteal and tibial arteries and used to calculate the pulsatility index and inverse damping factor. Results of each method were assessed by independent observers and compared with the arteriographic data. No appreciable difference was demonstrated between the two methods, both giving an overall accuracy in the 90% to 95% range. Both accurately predicted the severity of iliac and superficial femoral artery obstruction and distinguished iliac from proximal disease of the superficial femoral artery. Outflow disease (tibial arteries) was better assessed by measurement of segmental pressures than by Doppler waveform analysis or pulse-volume recording alone.

Angiography↗
PubMed1981

Incidental appendectomy?--Yes.

A consecutive group of 100 patients over the age of 40 years, who were operated upon for histologically proven acute appendicitis, were reviewed. Although there were no deaths, 36 had complications, of which 30 were related to wound infection. Thirty-one patients were found at operation to have perforation. Of these 100 patients, 13 could have had their appendices removed previously at the time of an elective laparotomy. The morbidity of incidental appendectomy was reviewed in 200 randomly selected patients, also over the age of 40 years, who underwent either elective hysterectomy or cholecystectomy. Half had an incidental appendectomy and the other half did not. The indication for appendectomy was the preference of the surgeon. There was no important difference in operative or postoperative problems in the two groups of patients. The authors conclude that incidental appendectomy is a worthwhile and safe procedure unless there are specific contraindications.

Acute Disease↗