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Biomedical subjects

F W LoGerfo

Publications and source records attributed to F W LoGerfo.

At least 91 records · Page 5Linked to original sources
PubMed1991

Popliteal-to-distal bypass grafts for limb salvage in diabetics.

Between January 1984 and August 1989, 117 diabetic patients with a palpable popliteal pulse but distal limb threatening ischaemia underwent 124 popliteal artery (or below) to distal bypass grafts. All grafts were intra-operatively monitored. The operative mortality was 0.8% and the 30 day primary patency 93%. Primary patencies at 1 and 3 years were 88.6 and 85.2%, respectively. The results of using the popliteal artery as the proximal graft inflow site in diabetes are comparable to other patient groups and to alternative more proximal inflow sites, but require a shorter length of vein graft with a shorter vein harvesting incision, avoid groin disection and result in a more peripheral operation.

Adult↗
PubMed1991

Thrombin inhibition by covalently bound hirudin.

Hirudin is the most potent known natural inhibitor of thrombin and is presently gaining popularity as an anticoagulant since recombinant and synthesized forms have become available. We have made use of recombinant hirudin (rHir) by covalently binding it to both biomolecules and prosthetic biomaterials. Heterobifunctional crosslinking reagents were used to derivatize rHir and form covalent crosslinks between rHir and albumin producing active conjugates. Both derivatized rHir and conjugates inhibited human alpha-thrombin similarly, however, both showed a ten-fold decrease of alpha-thrombin inhibition when compared to rHir alone using the tripeptide substrate, S-2238. Immobilization of 2.75 +/- 0.45 micrograms rHir on 1.0 cm2 Dacron prosthetic graft patches resulted in inhibition of 1.88 +/- 0.03 micrograms alpha-thrombin in solution (mean +/- SD, n = 3), which is a 8:1 molar ratio, respectively. rHir ED50 inhibition of 0.1 NIH U alpha thrombin stimulated whole blood platelet aggregation was 0.12 x 10(-6) microM. The conjugate ED50 inhibition was 1.37 x 10(-6) microM showing an eleven-fold loss of activity. We conclude that there is only a ten-fold loss of inhibitory activity when rHir is covalently immobilized and that this technique has a benefit of localizing antithrombin activity to surfaces or soluble carrier molecules.

Adenosine Triphosphate↗
PubMed1991

Persistent platelet activation by passivated grafts.

Vascular grafts in canines exhibit similar healing patterns to humans in that the graft surface forms a pseudointima over time but endothelializes only near the anastomotic sites. Thus the pseudointima at the midportion of the graft may represent a nidus for persistent platelet activation. The purpose of this investigation was to examine the effect of the maturing graft surface on platelet activation. Long Dacron subcutaneous carotid to aorta grafts (50 cm x 8 mm) were placed in nine dogs. Blood samples were obtained by direct graft puncture, at the proximal and distal ends of the graft, at 1, 24, 48, 72 hours, 1, 2, 3, 4 weeks, and monthly thereafter for 8 months. Seven sham dogs had subcutaneous grafts implanted without arterial anastomoses, and blood samples were drawn from the femoral artery. Platelet counts were determined with a platelet counter. Platelet aggregation and release of adenosine triphosphate was determined with a whole blood aggregometer by use of arachidonic acid, collagen, and adenosine diphosphate as agonists. No difference was found in platelet aggregation to collagen or adenosine diphosphate stimulation across the graft, but platelets released significantly less adenosine triphosphate to collagen and adenosine diphosphate stimulation distally versus proximally. In the graft dogs a decrease in systemic platelet counts of 50% occurred from the preoperative level which persisted over 8 months (p less than 0.01). Also less response occurred to collagen and ADP stimulated platelet aggregation in the graft animals than the sham animals during the first month of study. These data suggest that significant platelet-graft interactions occur even after the graft has formed a mature pseudointima.

Adenosine Triphosphate↗
PubMed1991

Continued experience with intraoperative angioscopy for monitoring infrainguinal bypass grafting.

Intraoperative angioscopy provides direct, in vivo, three-dimensional visualization of the interior of the blood vessels and grafts. We have shown previously that with the application of the basic principles of irrigation and with a dedicated irrigation pump that routine intraoperative angioscopy can be performed with consistent high quality results during lower extremity revascularization. In our total experience with angioscopy as a monitoring procedure during infrainguinal bypass grafting, 259 intraoperative angioscopies, during 63 femoropopliteal and 196 distal bypass grafts, were performed from May 1, 1987, to October 31, 1989. Mean total irrigation fluid used in the study was 448 ml (range, 0 to 1400 ml) with good visual quality in more than 80% of the studies. The overall failure rate was 1.5%. No complications were directly attributable to the insertion of the angioscope or the use of the pump. Based on the angioscopic findings, 124 clinical or surgical decisions were made in 259 of the angioscopies. The incidence of graft failure in this study was 8.1% (less than 30 days) and 4.8% (greater than 30 days) with a mean follow-up of 272 days. Direct inspection of the interior of the graft and native vessels at the time of surgery has resulted in the recognition of previously unsuspected vein-graft pathology. Angioscopy as the sole monitoring procedure for infrainguinal bypass grafting is safe, effective, and reliable and may not only improve the durability of these grafts but may improve our understanding of the pathogenesis of graft failure and of the progression of the underlying atherosclerotic disease.

Adult↗
PubMed1991

Angioscopically directed valvulotomy: a new valvulotome and technique.

Despite a large experience with "blind" retrograde valvulotomy in in situ vein bypass grafting, the incidence of residual competent valves remains high, and valvulotome-induced injury is common. In this study we describe a new valvulotome and technique of angioscopically directed valvulotomy and review the video tape recordings of 85 completion angioscopies of in situ femorodistal bypasses. Fifty-three vein grafts were prepared with the blind retrograde valvulotomy technique and 32 vein grafts with the new valvulotome and angioscopy. The use of the new valvulotome and technique is compared with that of the standard blind retrograde valvulotomy technique, and the normal endoluminal anatomy and incidence of primary disease in saphenous vein grafts was noted. The incidence of valvulotome-induced injury was 5/32 (15.6%) and 45/53 (85%) in vein grafts prepared with angioscopically directed valvulotomy and blind retrograde valvulotomy, respectively. Residual competent valves were found in 10/53 (18.9%) in blind retrograde valvulotomy and 0/25 of angioscopically directed valvulotomy vein grafts (p = 0.0114). In 22/53 vein grafts unsuspected primary disease was detected. Angioscopically directed valvulotomy with the new valvulotome and technique is feasible, reliable, and safe. It avoids residual competent valves, minimizes valvulotome-induced injury, and allows the detection and correction of unappreciated primary vein graft abnormalities. The new valvulotome and technique is a first step in the complete endoluminal preparation of the in situ vein graft.

Aged↗
PubMed1990

New angioscopic findings in graft failure after infrainguinal bypass.

We have previously shown that intraoperative angioscopy is a safe, useful, and effective method for monitoring infrainguinal bypass grafts. The videotaped recordings of the intraoperative angioscopy studies of 25 failed infrainguinal bypass grafts inserted between May 1987 and July 1989 and 3 failing grafts that were angioscoped during the subsequent graft salvage procedure were reviewed in a systematic fashion according to a fixed protocol, to identify any endovascular findings either initially missed or in which the relevance to graft failure had been unappreciated at the time of bypass grafting. We were able to identify new venous pathologic characteristics and highlight endoluminal features, of both a technical and nontechnical nature, which have a probable causal relationship to graft failure. However, the significance of some of the endovascular findings that were seen during infrainguinal bypass grafting has yet to be fully defined.

Adult↗
PubMed1990

Efficacy of the dorsal pedal bypass for limb salvage in diabetic patients: short-term observations.

Limbs of diabetic patients with distal tibial disease are frequently considered unreconstructible; however, when studied with intraarterial digital subtraction angiography, the dorsal pedal artery is frequently found to be patent. We have reviewed our recent experience with 96 patients, 94% of whom had diabetes and had 97 bypasses placed to the dorsal pedal artery. All procedures were for limb salvage. Superimposed infection was present in 42.3%. In 92 instances where intraarterial digital subtraction angiography successfully visualized the dorsal pedal artery, 91 bypasses were placed. In 12 other cases where the dorsal pedal artery was not visualized by intraarterial digital subtraction angiography but audible with the continuous-wave Doppler, bypasses were completed successfully in six. All procedures were performed with vein. Inflow was taken from the femoral artery in 48, popliteal artery in 45, tibial artery in 2, and from a femoral tibial graft in 2. Perioperative mortality was 1.92%. Actuarial graft patency, limb salvage, and patient survival were 82%, 87%, and 80%, respectively at 18 months. We conclude that bypass grafting to the dorsal pedal artery can be reliably performed with acceptable short-term results. An attempt should always be made to visualize the foot vessels angiographically, especially in diabetic patients, so that this valuable option in arterial reconstruction will not be overlooked.

Arterial Occlusive Diseases↗
PubMed1990

Pulsed and color Doppler analysis of normal carotid bifurcation flow dynamics using an in-vitro model.

An anatomically accurate model of the human carotid bifurcation was studied by using color Doppler flow mapping and pulsed Doppler signal analysis. In concordance with dye injection studies, a zone of flow separation was clearly demonstrated at the origin of the internal carotid artery opposite the flow divider. This zone of flow reversal was detected when the ratio of external to common carotid flow rates was greater than 0.27 and became progressively larger as the ratio increased, finally evolving into a zone of heterogenous flow at a ratio greater than 0.5. The authors conclude that the zone of flow reversal seen in the human carotid artery is a geometric property of the bifurcation and that its size depends on the relative flow between both branches. Doppler color imaging can be used to noninvasively map out its extent.

Blood Flow Velocity↗
PubMed1990

Results of vein graft reconstruction of the lower extremity in diabetic and nondiabetic patients.

The results of 171 vein grafts of the lower extremity were evaluated. These were placed between January 1981 and December 1987 in 150 patients, 75 diabetic and 75 nondiabetic, to determine the influence of diabetes on the outcome of the procedure. One and four year patency rates were determined by a life table analysis. No statistical differences in primary patency were found between the patients with diabetes and those without diabetes for all indications of operations (one year, diabetic patients 95 +/- 3 per cent, nondiabetic patients 85 +/- 3 per cent; four years, diabetic patients 89 +/- 11 per cent and nondiabetic patients 80 +/- 12 per cent; p = n.s.). For those operated upon for salvage of the limb because of rest pain, ulceration or gangrene, patency in diabetic patients at one year approached a statistically significant advantage (diabetic patients 94 +/- 4 per cent versus nondiabetic patients 79 +/- 8 per cent; p = 0.056). We believe that arterial reconstruction of the lower extremity can be performed upon patients with diabetes with the same high degree of success for revascularization and salvage of the limb as can be accomplished in nondiabetic patients. This is true even though those with diabetes present with necrosis of the tissue and more often require bypass to distal tibial arteries.

Actuarial Analysis↗
PubMed1989

The use of arm veins for infrainguinal bypass in end-stage peripheral vascular disease.

Thirty-six infrainguinal bypass grafts were performed in 33 patients with the use of autologous arm vein. Indications for operation were ischemic rest pain or tissue loss in all patients. The average age of the patients was 70.0 years-27% were diabetic and 66% were smokers. Sixty-five percent of the grafts were performed as secondary reconstructions. Follow-up ranged from three weeks to six years, with a mean of 12.1 months. Life-table primary and secondary patencies for all grafts are 73% and 82% at one year, respectively. Simple (noncomposite) arm vein grafts had primary and secondary patencies of 75% and 85%, respectively. The limb salvage rate was 86%. No grafts required thrombectomy for early occlusion (less than 30 days), and no graft failures have occurred beyond nine months (n = 18). Arm vein bypass grafts demonstrate excellent patency rates and provide the preferred conduit in the absence of autologous saphenous vein.

Aged↗
PubMed1989

Symptomatology and anatomic patterns of peripheral vascular disease: differing impact of smoking and diabetes.

We retrospectively examined the impact of smoking and diabetes on the clinical presentation and arteriographic pattern of occlusion in 227 patients evaluated for symptomatic infrainguinal arterial disease. The age at which significant symptomatology developed did not differ for diabetics and nondiabetics. Diabetics had significantly more occlusion in the large arteries of the calf, however, particularly in the peroneal and posterior tibial arteries. Despite this, the extent of occlusive disease in the pedal arch was not influenced by diabetes. Diabetics also tended to present more frequently with gangrene or ulcer (greater than 70%) when compared to nondiabetic smokers (41%, p less than .01). Smokers presented with symptomatic disease earlier than nonsmokers (p less than .0005). Intermittent claudication was strongly associated with smoking; among 33 patients with claudication, 32 were smokers. In contrast to the effect of diabetes, smokers appeared to have less extensive occlusive disease in the large arteries of the calf than nonsmokers. Nondiabetic nonsmokers constituted less than 10% of our study population and presented at a significantly older age. Nevertheless, despite the absence of either risk factor, this group also tended to present with gangrene or ulcer relatively frequently (71%). Although diabetes and smoking are both risk factors for atherosclerotic disease, we conclude that their impact on the angiographic pattern of occlusion and clinical presentation differs substantially.

Aged↗
PubMed1987

Human percutaneous and intraoperative laser thermal angioplasty: initial clinical results as an adjunct to balloon angioplasty.

In this study, the safety and efficacy of percutaneous laser thermal angioplasty as an adjunct to balloon angioplasty were investigated in 13 patients with severe peripheral vascular disease. By means of a novel fiberoptic laser delivery system (Laserprobe) in which argon laser energy is converted to heat in a metallic tip at the end of the fiberoptic fiber, improvement in the angiographic luminal diameter was noted in 14 of 15 femoropopliteal vessels (93%) by delivering 8 to 13 watts of continuous argon laser energy as the Laserprobe was advanced through the lesion. Initial clinical success (indicated by relief of symptoms and increase in Doppler index) for the combined laser and balloon angioplasty procedures was obtained in 12 of 15 vessels (80%), with inadequate balloon dilatation being the limiting factor in three patients. No significant complications of vessel perforation, dissection, pain, spasm, or embolization of debris occurred. Of the 12 patients who had procedures with initial angiographic and clinical success, 10 (83%) were asymptomatic in the initial follow-up period of 1 to 9 months (mean 6 months). Thus, laser thermal angioplasty with a Laserprobe is a safe and effective adjunct to peripheral balloon angioplasty. This technique has the potential to increase the initial success rate of angioplasty for lesions that are difficult or impossible to treat by conventional means. By removing most of the obstructing lesion, this technique may also reduce recurrent stenosis.

Angiography↗
PubMed1986

Successful vein bypass in patients with an ischemic limb and a palpable popliteal pulse.

Patients presenting with an ischemic foot who have a palpable popliteal pulse have not always been considered to be suitable candidates for arterial reconstruction. Since 1976, 32 distal bypasses were performed in 30 such patients, 77% of whom were diabetic. Proximal anastomoses were from the distal superficial femoral or popliteal artery. Autologous vein was used in all cases. There were six graft failures, all of which occurred within eight months. Three failures, which all occurred within the first month, required below-the-knee amputation. Using life-table analysis, the one- and three-year patency rates were both 79%. One- and three-year limb-salvage rates were 89% and 82%, respectively. We conclude that the results of distal vein graft reconstruction originating from the superficial femoral or popliteal artery are comparable with those of any group of patients with arterial occlusive disease of a lower extremity.

Adult↗
PubMed1986

Effect of inflow and outflow sites on the results of tibioperoneal vein grafts.

We have reviewed our experience with the tibial vessel bypass operation and have found the overall patency and limb salvage rates to be acceptable. Patients were divided into two groups based on the site of the proximal anastomosis. In Group I, the proximal anastomosis was at the common femoral artery and in Group II, the proximal anastomosis was at the distal superficial femoral artery or the popliteal artery. The patients in the two groups were similar with regard to indications for operation, age, and sex. However, in Group I, 35 percent of the patients were diabetic and in Group II, 74 percent of the patients were diabetic. In the Group I patients, the 72 month graft patency rate was 65 percent with a limb salvage rate of 75 percent. In the Group II patients, the 72 month patency rate was 81 percent with a limb salvage rate of 89 percent. Some possible explanations for this slightly better result in Group II patients are discussed. All tibial bypasses were divided into three groups based on the recipient tibial artery. Analysis revealed that the 72 month patency rates were as follows: the anterior tibial artery 63 percent, the posterior tibial artery 81 percent, and the peroneal artery 80 percent. These differences were not significant but indicate, as others have recently pointed out, that the peroneal artery is indeed an acceptable recipient artery for tibial bypass surgery.

Actuarial Analysis↗