Distal External Iliac Artery Research Articles

Duplex Arteriography Prior to Femoral-Popliteal Reconstruction in Claudicants: A Proposal for a New Shortened Protocol

The standard preoperative duplex arteriography (DA) from the aorta to the pedal vessels is time consuming and may be unnecessary in patients presenting with calf claudication alone. The feasibility of a shortened protocol was evaluated. Of 286 femoral-popliteal reconstruction based on DA during the last 4A years, 79 (28%) were primary operations for calf claudication. Eliminating the aortoiliac portion of the test except for the distal external iliac artery and limiting the scanning of the infrapopliteal vessels to one or two arteries in the leg would significantly shorten the exam. To confirm the adequacy of the inflow tract, we relied on the common femoral artery Doppler waveform analysis and the intraoperative graft pressure upon completion of the bypass. Of the 79 primary femoral-popliteal bypasses, 53 (67%) had triphasic common femoral artery waveform and the remaining 26 had monophasic or biphasic waveforms. Three (6%) of the 53 femoral-popliteal bypasses in the former group had significant pressure gradients measured intraoperatively and were treated with iliac angioplasties and stents for unsuspected stenoses in 2 cases and a covered stent for a common iliac aneurysm in 1 case. Three, two, and one infrapopliteal vessel runoff was observed in 24 (45%), 16 (30%), and 9 (17%) extremities, respectively. Four patients (8%) had significant stenoses (>50%) or occlusion of all three infrapopliteal arteries. Eighty-one percent of the patients would have completed the short protocol had we scanned the peroneal artery initially. An additional 8% would have required scanning of a second vessel (anterior tibial) and only 11%, scanning of all three infrapopliteal vessels. The time interval for completion of short-protocol DA was significantly less than the time for the standard DA (16.2 A+/- 5.2A min vs. 35.1 A+/- 10.6 min) ( p < 0.01). We believe that the proposed short DA protocol combined with intraoperative graft pressure measurements can be used in 94% of the patients who have a patent popliteal artery (>/= 7 cm). It is a totally noninvasive approach that is particularly suitable for vascular technologists and surgeons who wish to start utilizing DA instead of contrast arteriography prior to infrainguinal reconstructions. However, the short protocol does not avert the need for completion arteriography of the inflow arteries and readiness to perform endovascular procedures to correct lesions not suspected by common femoral artery waveform analysis.

Association of pelvic arterial calcification with arteriovenous thigh graft failure in haemodialysis patients.

Arterial calcification is a common problem in patients with chronic kidney disease, and has been associated with adverse clinical outcomes. The goal of the present study was to evaluate whether pelvic artery calcifications are associated with technical failure of arteriovenous thigh grafts in haemodialysis patients. From 1 January 1999 to 30 June 2002, thigh grafts were placed in 54 haemodialysis patients who had exhausted all options for permanent vascular access in the upper extremities. Perioperative computed tomography (CT) of the abdomen and pelvis was obtained in 32 of the patients for diagnostic purposes unrelated to vascular access planning. Two radiologists, who were blinded to the graft outcomes, scored the vascular calcifications on CT of the distal aorta, common iliac, external iliac and common femoral arteries on a semi-quantitative 5-point scale. The association between technical graft failure (inability to complete the anastomosis) and the vascular calcification score was analysed. There was a high inter-observer agreement in scoring vascular calcification (kappa = 0.801). Among 26 patients with absent or mild pelvic arterial calcifications (grade 1-2) on CT, none (0%) experienced technical graft failure. In contrast, three of six patients (50%) with moderate to severe calcification (grade 3-5) had technical graft failures (P = 0.004 by Fisher's exact test). The cumulative 1 year graft patency was lower in the group with grade 3-5 calcification (33 vs 81%, P = 0.09). The two groups were similar in age, gender, race, diabetes, duration of dialysis, serum calcium, serum phosphorus and serum parathyroid hormone. There is a strong association between pelvic artery calcifications and technical failure of thigh grafts. The presence of moderate to severe vascular calcification is predictive of poor cumulative 1 year graft patency.

The effect of vascular endothelia growth factor encapsulated in nanoparticles on chronic limb ischemia

To experimentally investigate direct intramuscular gene transfer of nanoparticles encoding vascular endothelial growth factor for the treatment of peripheral artery disease. The human VEGF(165) cDNA was cloned into the eukaryotic expression vector PIRES2 under the control of cytomegalovirus promoter/enhancer. The recombinant gene was transferred into a rabbit model of chronic hindlimb ischemia by naked plasmid and nanoparticle respectively. Ischemia was induced in the hindlimb of New Zealand White rabbits by ligation of the distal external iliac artery and complete excision of the femoral artery and all its branches. At day 7 postoperation animals received VEGF(165) plasmid (10 intramuscular) or nanoparticle-VEGF(165) (8 intramuscular). With RT-PCR, immunohistochemistry analysis, and angiography, the expression and biological effects of VEGF(165) gene in experimental animals were investigated. Two weeks after initiation of therapy, angiography showed that the transfer of VEGF(165) gene stimulated the formation of focal neovessels and established collateral circulation. The adductor muscle of ischemic limbs was histologically examined at day 14. Capillary density was increased among VEGF(165)-transfected rabbits, especially Nano-VEGF(165)-treated animals (Naked VEGF(165) plasmid = 50.18 per mm(2), Nano-VEGF(165) = 81.22 per mm(2), Control = 29.54 per mm(2), P < 0.05). RT-PCR showed that the transcription and expression of VEGF(165) gene in experimental group were significantly higher than those of control groups. Intramuscular administration of VEGF(165) induces collateral artery augmentation in the rabbit model of chronic limb ischemia. Nanoparticle can act as a vector to transfect specific gene and it will benefit gene transfer.

Emerging role of endovascular grafts in complex aortoiliac occlusive disease.

Aortobifemoral bypass is the standard therapy for complex aortoiliac occlusive disease. The purpose of this study was to examine the use of endovascular grafts as an alternative to aortobifemoral bypass in patients with advanced aortoiliac occlusive disease at high risk. Endovascular grafts were placed in 23 limbs in 22 patients with TransAtlantic Inter-Society Consensus document (TASC) type C and D lesions. All procedures were performed in the operating room, and images were obtained with portable digital fluoroscopy. Surgical exposure of the ipsilateral common femoral artery was performed to enable safe closure of 9F to 12F sheath sites and to facilitate ipsilateral interventions in the distal external iliac artery. Concomitant infrainguinal outflow procedures were performed in 6 patients. Twenty of 22 patients were men; mean patient age was 63.2 +/- 3.2 years. Indications for intervention were rest pain in 12 of 23 limbs and tissue loss in 9 of 22 limbs. Risk factors included hostile abdomen or pelvis in 8 patients, coronary artery disease in 11 patients, end-stage renal disease in 3 patients, and severe chronic obstructive pulmonary disease in 3 patients. Each patient received a mean of 1.6 grafts. Initial technical success was 95.2%, with one technical failure. There was no 30-day mortality. All patients experienced at least one grade improvement per Society for Vascular Surgery reporting standards. Primary patency at 24 months was 84.2% +/- 8.0%, with a limb salvage rate of 95.3% +/- 5.0%. Mean (+/- SD) ankle brachial index improved from 0.49 +/- 0.22 to 0.87 +/- 0.26 (P <.001). Endovascular grafting to treat advanced aortoiliac occlusive disease can be accomplished with good clinical outcome and acceptable short-term patency. This endovascular technique can be a viable alternative to conventional surgical revascularization in patients with advanced aortoiliac occlusive disease at high risk.

The Hemodynamic Relationships that Exist between Various Parts of the Lower Extremity Arterial Circuit Containing a Bypass Graft: Case Study

Introduction Circuits containing bypass grafts are made up of four elements: (1) the inflow tract, (2) the graft, (3) the collateral beds, and (4) the outflow tract. The fundamental principles developed by Poiseuille, Ohm, and Bernoulli can facilitate our understanding of the hemodynamics that occur within the arterial circuit containing bypass grafts. Case Report A 59-year-old man was seen at our diagnostic vascular unit with severe claudication. Invasive and noninvasive vascular studies revealed occlusion of his aorta and bilateral common iliac arteries with reconstitution at bilateral groins by way of visceral vessels. Elective aortobifemoral bypass graft surgery was performed. Postoperatively, duplex ultrasonography (Phillips/ATL 5000, Bothell, WA, 7-MHz linear array transducer) performed on bilateral groins revealed prograde flow distal to the anastomoses and retrograde flow involving the distal external iliac arteries proximal to the anastomoses. Discussion Depending on the outflow resistance, flow might be prograde to the leg or retrograde to the pelvis and/or muscle proximal to the anastomosis or a combination of both as demonstrated in this case study. Such retrograde flow is desirable when one needs to perfuse the pelvis or thigh and not desirable if it steals blood from distal circulation. Conclusions The preceding fundamental principles refer to flow and pressure as inseparable manifestations of the total energetics of circulation. These principles are applied to the following case study and demonstrate competitive flow and pressure resistance relationships that exist within the arterial circuit containing a bypass graft.

Electrical stimulation promotes angiogenesis in a rabbit hind-limb ischemia model.

In previous investigations, it was shown that applying a modest regimen of electrical stimulation (ES), even in severely ischemic tissue, improves the healing process, accelerates neovascularization, and enhances angiogenesis in muscle tissue. Our objective in this current report was to further understand ES as a potential alternative treatment for severe muscle ischemia. Immediately after the left distal external iliac artery and the femoral artery were excised, ES (30 contractions per minute [cpm], 2 V, single impulses per burst) was applied to rabbit adductor muscle near the site of the excised femoralis artery for 24 hours daily over 1 month. Three other series served as controls: ES without arterial excision; arterial excision without ES or lead implantation; and arterial excision with lead implantation but no ES. Histologic study of capillary density was performed by angiography (employing a grid template) and by measuring the lower limb-calf blood pressure ratio. At the end of 30 days in the ES series, 10.5 +/-1.2 contrast-medium opacified arteries (COAs) crossed a specific grid section segment compared with 7.2 +/-1.5 in the control series without ES (p<0.05); 68.2 +/-9.3 COAs crossed a grid section compared with 43.2 +/-6.4 in controls (p<0.05); 27.3 +/-1.2 grids contained COAs compared with 29.3 +/-3.5 in controls (p<0.05); lower limb-calf blood pressure ratio was 0.81 +/-0.06 compared with 0.31 +/-0.07 in controls (p<0.05); and capillary density was 283.7 +/-24.5 mm2 compared with 91.4 +/-20.9 mm2 in controls (p<0.001). These preliminary results show that cautious ES enhances and accelerates muscle revascularization in severely ischemic tissue.

Retroperitoneal Haematoma Following the Popliteal Approach for Subintimal Angioplasty

Introduction given intra-arterially before advancing a balloon catheter subintimally to the level of the femoral head. Retroperitoneal haematoma is an uncommon comPrimary technical failure occurred when attempts to re-enter the true lumen of the vessel were unsuccessful. plication following the antegrade femoral approach for subintimal angioplasty and is usually caused by Limited contrast extravasation was seen at the level of the femoral head during re-entry attempts. The high groin puncture of the distal external iliac artery. We report a unique case of a retroperitoneal haemprocedure was compicated further by distal embolism to the peroneal artery, managed conservatively by an atoma caused by vessel perforation during an attempted subintimal angioplasty of a superficial intravenous heparin infusion started after the angioplasty attempt was abandoned. femoral occlusion using a retrograde popliteal approach. Six hours following the procedure, the patient became hypotensive. On examination, there were no signs of haematoma at the puncture site in the right popliteal fossa. The abdomen was distended with Case Report tenderness in the right iliac fossa. There was no external evidence of bleeding in the right inguinal region. A 75-year-old male smoker presented with disabling The haemoglobin level fell from 13 to 8 g/dl. An claudication and occasional rest pain in the right leg. abdominal CT scan was peformed which showed a A diagnostic arteriogram via a retrograde left femoral huge right retroperitoneal haematoma (Fig. 2). Folapproach demonstrated a long right superficial femlowing transfusion of eight units of blood, blood presoral artery occlusion, with reconstitution of the popsure and haemoglobin level stabilised. The right foot liteal artery just above the level of the knee joint. remained viable and the patient is currently being As the origin of the superficial femoral artery was considered for reconstructive surgery. occluded, a subintimal angioplasty was attempted via a retrograde popliteal approach. The right popliteal artery was punctured under ultrasound guidance. The Discussion distal popliteal and peroneal arteries were patent (Fig. 1), with reconstitution of the anterior and posterior Retrograde puncture of the popliteal artery is a welltibial arteries at the ankle. Heparin (2000 units) was recognised technique for percutaneous transluminal angioplasty of the superficial femoral artery and has also been reported as an alternative approach to sub∗ Please address all correspondence to: A. Loh, Department of intimal angioplasty of superficial femoral artery ocVascular Surgery, Barnet Hospital, Barnet, Hertfordshire EN5 3DJ, U.K. clusions. Indications include a failed antegrade

Common femoral artery ligation and local debridement: A safe treatment for infected femoral artery pseudoaneurysms

Purpose: The management of infected femoral artery pseudoaneurysms (IFAPs) is difficult and controversial. Use of synthetic or autologous conduit during arterial revascularization in these cases is complicated by the presence of sepsis and unavailability of autologous venous conduit. We present the results of common femoral artery (CFA) ligation and local drainage with debridement for the treatment of IFAP. Methods: A retrospective chart review of six consecutive patients from 1995 to 1999 who presented with IFAP from intravenous drug abuse was performed. Inpatient records, anesthesia records, and outpatient clinic charts were reviewed. All patients were men with right-sided lesions. All six patients abused heroin, and five (83%) abused heroin and cocaine. All six patients had a duplex ultrasound scan, and five (83%) patients had a digital subtraction angiogram to confirm the clinical diagnosis. Proximal vascular control was achieved retroperitoneally through an oblique suprainguinal incision. After vascular isolation and test clamping of the distal external iliac artery (EIA), the pedal pulses were examined with continuous wave Doppler scan. If a Doppler signal was present, this was followed with CFA ligation and local drainage and debridement of the IFAP. Results: Pain at injection site and fever with chills were present in five (83%) and three (50%) patients, respectively. A pulsatile groin mass and thigh or leg edema were present in five (83%) patients. Three patients (50%) had a palpable pedal pulse, and all six had a Doppler signal over a pedal artery at presentation. The mean white cell count was 15.6 thousand per cubic millimeter (range, 9.2-19.3). All patients had a Doppler signal over a pedal artery after distal EIA/CFA test occlusion and ligation. None of the patients required an amputation, and all six patients regained their preoperative ambulatory status. The mean follow-up period was 25 months. Two patients had mild claudication (5-6 blocks) at 18 months and 2 years after surgery. All six patients received drug rehabilitation, but they admitted to drug abuse after surgery and rehabilitation. Conclusion: CFA ligation and local debridement are safe treatment modalities for IFAP, if there is an intraoperative Doppler signal over a pedal artery during test occlusion of the distal EIA/CFA. CFA ligation avoids the use and therefore the risk of synthetic conduit infection, because there is a high incidence of postoperative drug injection despite aggressive drug rehabilitation. (J Vasc Surg 2001;33:990-3)

An experimental model of ischemia in rabbit hindlimb.

This study was performed to establish an experimental model of ischemia for the investigation of new treatment modality of limb-threatening ischemia. We produced ischemia in the hindlimbs of 8 New Zealand white rabbits. Under general anesthesia, the left femoral artery was exposed, freed, and excised from distal external iliac artery to proximal popliteal and saphenous arteries. And then both hindlimbs were serially examined to assess the ischemia according to the time table until postoperative 6 weeks. We assessed clinical observation, blood pressure, radioisotopic perfusion scan, and angiography. Clinical ischemic changes of the operated feet were observed in 63%. The blood pressure of left calves was measurable on postoperative day 3 (p<0.05, vs preoperative day 2) and then gradually increased to reach a plateau in postoperative week 6. Radioisotopic arterial perfusion showed similar profiles as in blood pressure. Angiography of ischemic hindlimbs demonstrated a few collateral vessels arising from the internal iliac artery with the reconstitution of the posterior tibial artery in postoperative week 2. In postoperative week 6, collaterals remained the same in number. However, these became dilated and tortuous and showed reconstitution in distal hindleg. In conclusion, this is a reproducible, measurable, and economical animal model of hind limb ischemia.

Bilateral External Iliac and Common Femoral Artery Disruptions After Blunt Trauma*

Blunt trauma to the external iliac or common femoral artery is relatively rare. Since its original description as the "motor-scooter handlebar syndrome," this type of injury has been hypothesized as resulting from compression of the artery by the inguinal ligament. We report a case of mirror-image arterial injuries from blunt trauma. At operation, each distal external iliac and proximal common femoral artery was found to have large intimal flaps. Resection of the injured segments with bilateral saphenous vein interposition grafts led to a successful outcome.

Relocation of the Iliac Artery Bifurcation to Facilitate Endoluminal Treatment of Abdominal Aortic Aneurysms

To report a surgical technique to preserve the internal iliac arteries (IIAs) and facilitate endovascular repair of abdominal aortic aneurysms (AAAs) with extensive iliac artery involvement. A new iliac artery bifurcation is created surgically through an 8-cm lower left abdominal incision by implanting the IIA onto the distal external iliac artery either directly or by using a tube graft interposition. Careful technique is required to avoid embolic complications, but after relocating the bifurcation, aortic endografting can be performed, either simultaneously or staged, depending upon patient characteristics. Relocation of the iliac artery bifurcation appears to be a good alternative to preserve pelvic arterial flow in selected candidates for endoluminal AAA repair.

Femoral artery exposure for endovascular aneurysm repair through oblique incisions.

To offer an alternative technique for accessing the femoral artery prior to endovascular grafting. An oblique incision is made over the medial half of the inguinal ligament and continues to the femoral sheath, which is opened longitudinally. The distal external iliac artery and proximal common femoral artery are isolated. A tiny stab wound is made distal to the primary wound for femoral artery puncture and catheter access. Using an oblique incision at the level of the inguinal ligament optimizes exposure for endograft insertion and may minimize the frequency of serious wound complications.

Femoral Artery Exposure for Endovascular Aneurysm Repair through Oblique Incisions

Purpose: To offer an alternative technique for accessing the femoral artery prior to endovascular grafting. Technique: An oblique incision is made over the medial half of the inguinal ligament and continues to the femoral sheath, which is opened longitudinally. The distal external iliac artery and proximal common femoral artery are isolated. A tiny stab wound is made distal to the primary wound for femoral artery puncture and catheter access. Conclusions: Using an oblique incision at the level of the inguinal ligament optimizes exposure for endograft insertion and may minimize the frequency of serious wound complications.

Stenting Without Thrombolysis for Aortoiliac Occlusive Disease: Experience in 14 High-Risk Patients

Stenting without thrombolysis of 16 occluded iliac artery segments and one occluded infrarenal abdominal aorta was attempted in 14 patients. All patients were either considered to be prohibitive operative risks or had contraindications to thrombolytic therapy. Indications for limb reperfusion included rest pain, disabling claudication, or dry gangrene. Successful recanalization was achieved primarily in 13 patients with self-expandable Wallstents, balloon-expandable Palmaz stents, or a combination of the two stents. Follow-up was carried out in all patients in whom recanalization was successful. All stented patients showed symptomatic improvement, and the mean preprocedure ankle/brachial index, which was 0.31, improved to 0.78 after the procedure (p = 0). Complications included a vertebrobasilar stroke during the procedure in one patient, perforation during angioplasty of a stenotic but nonoccluded external iliac artery in one, and dissection of the distal external iliac artery in one. Distal embolization did not occur. Percutaneous recanalization of aortoiliac occlusions without initial thrombolysis is possible and has a high potential for technical success. Additional data and longer follow-up are still needed, but this procedure may provide a reasonable, less invasive option in some patients at high surgical risk or in patients who have contraindications to thrombolytic therapy.

A persistent hindlimb ischemia model in the rabbit.

The study of new approaches for the treatment of limb-threatening ischemia has been hampered by the lack of a suitable animal model of persistent limb ischemia. We describe the development and evaluation of an animal model of persistent hindlimb ischemia, in which ischemia was induced in the left hindlimb of 28 rabbits by ligation of the distal external iliac artery and excision of the common and superficial femoral arteries. The severity of the ischemia and its relief in each animal were evaluated every 10 days postoperatively until day 40 (all animals) or day 90 (five animals). Nine animals developed superficial tissue necrosis in the foot, but no deaths were attributable to the ischemia-inducing procedure. Angiography demonstrated minimal collateralization and sluggish filling of distal vessels up to postoperative day 90. This was accompanied by a decrease at rest in the calf blood flow ratio (p < 0.005 vs day 0), an increase in lactic acid in the femoral venous blood (left vs right side, p < 0.002) up to postoperative day 40, and a decrease in the calf blood pressure ratio (p < 0.0001 vs day 0) up to day 90. Histologic study of the gastrocnemius muscle demonstrated evidence of atrophy and fibrosis in the left hindlimb. This model can be used to evaluate direct and indirect approaches to the treatment of chronic limb ischemia.

Penetrating thermal vascular injury in a child: A case report

Penetrating vascular trauma in children is most commonly seen in wartime settings or more recently as a result of attempts at invasive imaging. Treatment of these patients can be more complicated than treatment of trauma in adults and must include maintenance of symmetric limb growth, compensatory growth of the vascular graft and its anastomoses, and the need for very long-term graft patency. This report describes the care of a 5-year-old child who was impaled by a hot metal pipe and sustained a penetrating thermal injury to the distal external iliac artery and vein. Issues such as conduit choice, extraanatomic reconstruction, anastomotic suture technique, and soft tissue coverage are reviewed in the report.

Enhanced revascularization of the ischemic limb by angiogenic therapy.

This study tests the efficacy of an angiogenic growth factor, endothelial cell growth factor, in a rabbit model of persistent hindlimb ischemia. Ischemia was induced in the left hindlimb of 22 New Zealand White rabbits by ligation of the distal external iliac artery and complete excision of the common and superficial femoral arteries. Two groups of animals were studied: Group 1 consisted of 11 animals who for 10 days received daily intramuscular injections of 4 mg of endothelial cell growth factor beginning on postoperative day 11, and group 2 consisted of 11 animals who underwent the same surgical ischemic procedure but received only injections of saline daily for the same postoperative period. Perfusion of the ischemic left limb was compared with the normal right limb in each animal on postoperative days 10, 20, 30, and 40 using the calf blood pressure ratio, 99mTc macroaggregate radioisotopic perfusion scans, and serial angiography. Neovascularization in the left thigh at day 40 was quantified from the angiograms. Each technique documented that animals in group 1 had significantly better perfusion than animals in group 2; that is, the calf pressure ratio was higher in group 1 than in group 2 (0.56 versus 0.32 at day 20, 0.64 versus 0.44 at day 30, and 0.70 versus 0.50, P < .0001), and the calf radioisotopic perfusion ratio was also higher in group 1 than in group 2 (0.88 versus 0.74 at day 20, P < .02; 0.93 versus 0.76 at day 30, and 0.96 versus 0.79 at day 40, P < .008). Angiographic studies correlated well with these results demonstrating much earlier distal arterial reconstitution and enhanced neovascularization (23.8 versus 9.0 vessels, P < .007). The data clearly indicate that an angiogenic growth factor, endothelial cell growth factor, promotes revascularization in this experimental ischemic hindlimb model, raising the possibility that in the future such agents might be of value in humans.

“Shaggy” Aorta Syndrome with Atheromatous Embolization to Visceral Vessels

Spontaneous atheromatous visceral embolization from diffuse aortic atherosclerotic disease is an unusual and poorly understood entity. We have reviewed our experience with 88 patients who suffered atheromatous embolization from a "shaggy" aorta. Visceral embolization was evident in 36 patients (40.9%). Nine were treated nonoperatively with three patients dying within a week of presentation and an additional five patients dying within five years due to continuing renal and intestinal embolization. Surgical correction was undertaken 28 times in 27 patients. Endarterectomy or graft replacement of the aorta did not necessarily prevent visceral infarction or renal failure. Extra-anatomic bypass with ligation of the distal external iliac arteries appears to be associated with the lowest morbidity and mortality. Anticoagulation of these patients does not prevent embolization and may be contraindicated for long-term management.

Patency and Intimal Hyperplasia: The Effect of Aspirin on Small Arterial Anastomosis

This experiment evaluated the effect of aspirin (ASA) on the patency and development of intimal hyperplasia in autologous, small caliber, arterial end-to-side anastomosis. Twenty-eight adult female rabbits had their distal left external iliac artery transposed and anastomosed to the right proximal external iliac artery. Fourteen rabbits received ASA 40 mg by gavage twice in the 24 hours preceding the operation and 5 times a week postoperatively (experimental) and 14 rabbits received no ASA therapy (control). Plasma salicylate levels range from 25 to 36 micrograms per milliliter in experimental animals. Patency of the reconstruction was assessed by Doppler examination each month, confirmed by autopsy and calculated by life table analysis. Five cross sections of each patent anastomosis harvested at six and nine months were examined by light microscopy. A total of seven thromboses occurred in the control group versus two occlusions in the experimental group. Four of the thromboses in the control group occurred less than seven days after the reconstruction, whereas no such events occurred in the experimental group. Patency by actuarial methods at nine months was 45.5% versus 81.8% (p less than .05) in control and experimental groups, respectively. This improvement occurred in spite of similar values for intimal thickness and lumen-to-basement membrane ratios in both control and experimental groups. We conclude that aspirin significantly improves the nine month patency rate of small autologous end-to-side anastomosis, and its effect is most noticeable in the early postoperative period.(ABSTRACT TRUNCATED AT 250 WORDS)

Regional wave travel and reflections along the human aorta: a study with six simultaneous micromanometric pressures.

The human aorta and its terminal branches were investigated in normal subjects during elective cardiac catheterization to evaluate regional wave travel and arterial wave reflections. A specially designed catheter with six micromanometers equally spaced at 10 cm intervals was positioned with the tip sensor in the distal external iliac artery and the proximal sensor in the aortic arch. Simultaneous pressures were obtained and analyzed for foot-to-foot wave velocity, and Fourier analysis was used to derive apparent phase velocity. These quantities were assessed during control (n = 9), during Valsalva (n = 8) and Müller (n = 4) maneuvers, and during femoral artery occlusion by bilateral manual compression (n = 8). During control, regional cross-sectional areas, determined from aortography, and regional foot-to-foot pulse wave velocities were used to calculate the local reflection coefficient in the proximal descending aorta (gamma = 0.05), at the junction of the renal arteries (gamma = 0.43), and at the terminal aortic bifurcation (gamma = 0.13). To test the hypothesis that significant reflections originate in the aorta, at the level of the renal arteries, aortograms were used to design a latex tube model with geometric properties similar to the descending aorta. Velocities and reflection characteristics in the model and in vivo were compared. Inspection of thoracic aortic pressures under control conditions revealed a reflected wave originating from the region of the aorta at the level of the renal arterial branches while abdominal pressures exhibited reflection from a site peripheral to the terminal aortic bifurcation. In the low frequency range, apparent phase velocity was found to be higher proximal to the renal arteries as compared with at the distal sites. In addition, the minimum value occurred at a higher frequency in the lower thoracic aorta than at more distal sites. The effects of reflection on apparent wave velocity in the tube model were consistent with data obtained in vivo. The Valsalva maneuver diminished the reflection from the aortic region of the renal arteries, thus allowing the distal reflected wave to become more evident on the thoracic pressure waveforms. Bilateral femoral artery occlusion usually enhanced the distal reflection and the Müller maneuver usually resulted in small increases in reflections. In conclusion, the geometric and elastic nonuniformity of the aorta results in two major sites of arterial wave reflection that influence the aortic pressure waveforms in man.(ABSTRACT TRUNCATED AT 400 WORDS)