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Biomedical subjects

T E Brothers

Publications and source records attributed to T E Brothers.

At least 37 records · Page 2Linked to original sources
PubMed1995

Is infrapopliteal bypass compromised by distal origin of the proximal anastomosis?

Distal origination of the proximal anastomosis (DOPA) of an infrapopliteal bypass beyond the adductor hiatus minimizes the length of graft required and optimizes use of scarce autogenous conduit. Sixty-two DOPA infrapopliteal revascularizations using autogenous vein performed for limb salvage over a 7-year period were reviewed and compared with 203 concurrent infrapopliteal bypasses originating more proximally (POPA). Life-table analysis revealed no difference at 54 months between DOPA and POPA bypass with regard to primary patency (57% vs. 50%, respectively) or secondary patency (67% vs. 65%, respectively). Differences in limb salvage at 54 months between DOPA and POPA bypasses did not reach statistical significance (53% vs. 66%, p = 0.12), although DOPA fared worse. Inferior limb salvage results in all infrapopliteal bypasses were correlated with the presence of tissue necrosis (52% vs. 70%, p < 0.001), which was more prevalent in patients undergoing DOPA bypass (71% vs. 49%, p < 0.01). The long-term patency of infrapopliteal bypass appears only marginally affected by DOPA. However, the prognosis for limb salvage in this setting is compromised as a result of the virulent behavior of the atherosclerotic disease that spares the superficial femoral artery while predominantly involving the popliteal and tibial vessels.

Aged↗
PubMed1995

Protamine use during peripheral vascular surgery: a prospective randomized trial.

PURPOSE: One hundred twenty patients undergoing aortic reconstruction (40), infrainguinal bypass (49), and carotid endarterectomy (31) were prospectively enrolled into a double-blind randomized trial to investigate the utility of routine heparin reversal with protamine. METHODS: All patients underwent systemic heparinization with 90 U/kg body weight during operation and after revascularization were randomized to receive either protamine or saline solution for heparin reversal. Blood loss was measured throughout the surgical procedure, and indexes of coagulation and the requirement for blood and blood products were documented during operation and the first 24 hours after operation. RESULTS: Plasma heparin concentration, partial thromboplastin time, and activated clotting time were significantly higher (p < 0.05) in those receiving saline solution at 20 minutes and 1 hour after administration. Total surgical blood loss was not significantly different between study groups. No significant differences were found in blood product requirement, intravenous fluid administered, hematocrit, or wound hematomas between groups at 24 hours. In addition, no difference was seen in the surgeon's subjective intraoperative assessment of hemostasis after administration of either study drug. Furthermore, after study drug administration protamine was associated with a deleterious effect on subsequent intraoperative blood loss (318 +/- 33 ml vs 195 +/- 18 ml, p < 0.05). CONCLUSIONS: Although protamine effectively reverses heparin anticoagulation, its routine use after elective peripheral vascular surgical reconstruction does not appear to provide any clinical benefit.

Aged↗
PubMed1995

Stratification of mortality risk for renal artery surgery.

Seventy consecutive operations involving the renal arteries were reviewed to identify factors linked to perioperative mortality. Aortorenal bypass (n = 29), endarterectomy (n = 12), extraanatomic bypass (n = 12), thrombectomy (n = 4), and reimplantation (n = 13) were associated with a 16% perioperative mortality that was often secondary to multisystem organ failure. Patients who died exhibited a higher serum creatinine (3.4 vs 2.1 mg/dL; P < 0.05). Stratification of patients by risk revealed higher American Society of Anesthesiologists (ASA) (P < 0.005) and modified Acute Physiology Score, and Chronic Health Evaluation (APACHE II) (P < 0.02) score among patients who died. Higher mortality was also observed after bilateral renal artery operations (31% vs 5%; P < 0.005) or concomitant mesenteric revascularization (37% vs 12%; P < 0.05), but not simultaneous aortic procedures (18% vs 11%; P = NS). Bilateral operation (P < 0.0001), age (P < 0.001), and ASA class (P < 0.01) were independent predictors of mortality according to multivariate analysis. Because of higher mortality in these specific situations, modification or limitation of operative scope may be appropriate.

APACHE↗
PubMed1994

Aortic dissection originating in the suprarenal abdominal aorta.

Spontaneous dissection of the abdominal aorta originating from the suprarenal aorta is very rare. Previous reports attest to the lethal nature of this disorder. This case represents the first report of successful repair of a spontaneous suprarenal abdominal aortic dissection by graft insertion with obliteration of both the entrance tear and the false lumen with reimplantation of the visceral vessels.

Aged↗
PubMed1993

Limitations of peroneal artery bypass grafting for limb salvage.

PURPOSE: The purpose of this study was to compare the results of peroneal bypass grafting for limb salvage with the results of other tibial and pedal bypass grafts performed concurrently. METHODS: Thirty-four peroneal bypass grafts with autologous vein were performed for limb salvage between September 1986 and June 1992. These constituted 18% of an overall experience of 194 tibial or pedal bypasses performed during that time. Preoperative and intraoperative arteriograms were reviewed to identify anatomic characteristics associated with successful limb salvage. RESULTS: Secondary patency rates for peroneal bypass grafts (70%) compared with the other tibial and pedal bypass grafts (65%) did not differ significantly at 48 months by life-table analysis. Limb salvage achieved by peroneal artery bypass grafting was significantly worse (55%) than that achieved by the remaining tibial and pedal bypasses (67%) at 48 months. Limb salvage was 33% at 7 months for those undergoing peroneal artery bypass grafting as opposed to 57% at 48 months for patients undergoing other tibial or pedal revascularizations with tissue necrosis. Four anatomic features were identified that were associated with failure after peroneal artery bypass grafting. These were peroneal length less than 10 cm (p = 0.012), peroneal artery diameter less than 2 mm (p = 0.035), absence of arteriographically demonstrated collaterals perfusing the foot (p = 0.0001), and little or no visualization of the pedal arch (p = 0.008). CONCLUSIONS: Although successful grafts may avoid amputation in carefully selected cases, alternatives to peroneal artery bypass grafting should be considered when less than favorable anatomic conditions are encountered, particularly in the presence of forefoot tissue necrosis.

Aged↗
PubMed1993

Effects of lumbar sympathectomy on canine transcutaneous oxygen tension.

Augmentation of cutaneous blood flow by postganglionic lumbar sympathectomy may not reflect an increase in nutritive vascular supply to the dermal tissues. Transcutaneous oxygen tension (TcPO2) was compared with radionuclide microsphere determination of dermal microcirculation in a hind limb sympathectomy model in 20 dogs. After 90 minutes the TcPO2 was greater in the sympathectomized limbs than in the contralateral limbs (125 mm Hg versus 114 mm Hg, p < or = 0.05). In contrast, microsphere-determined paw dermal capillary flow declined in sympathectomized limbs (4.9 ml/min/100 gm versus 11.8 ml/min/100 gm, p < or = 0.05). Decreases in the TcPO2/venous PO2 ratio correlated with sympathectomy-induced increases in total limb blood flow (r = 0.60; p < or = 0.001), reflecting less efficient oxygen extraction. These observations confirm the lack of enhancement of tissue oxygen delivery by sympathectomy because of the associated dilation of cutaneous arteriovenous shunts.

Animals↗
PubMed1992

Adhesion and incorporation of lacZ-transduced endothelial cells into the intact capillary wall in the rat.

Use of the capillary bed of skeletal muscle as an in vivo recipient site to transplant autologous endothelial cells that have undergone gene transfer ex vivo has considerable potential as a technique of somatic gene therapy. Here we document a previously unrecognized capacity of endothelial cells to adhere and incorporate spontaneously into confluent endothelial cell monolayers in vitro and in vivo. This spontaneous adhesion and incorporation of endothelial cells enabled us to seed lacZ-transduced endothelial cells into the wall of skeletal muscle capillaries of the hindlimb of the rat. Certain transduced endothelial cells became incorporated within the capillary wall, whereas others remained within the capillary lumen where they formed focal, electron-dense, contacts with host endothelium. lacZ expression in the capillary bed was documented for up to 1 month after transplantation. Use of the intact capillary bed of skeletal muscle as an in vivo recipient site for transduced, autologous endothelial cells holds promise as a strategy for somatic gene therapy to treat various genetic and acquired human diseases.

Animals↗
PubMed1991

The role of an endothelial cell lining in limiting distal anastomotic intimal hyperplasia of 4-mm-I.D. Dacron grafts in a canine model.

The effect of an endothelial cell (EC) lining on intimal hyperplasia at the distal anastomosis of Dacron grafts was assessed in a canine model. Enzymatically derived autologous EC were used to seed 14 to 17 cm long, 4 mm I.D., knitted Dacron aortoiliac grafts implanted in an end-to-side manner in six dogs (Group I). Unseeded grafts were similarly implanted in six control dogs (Group II). All animals received acetylsalicylic acid (325 mg po qd) 24 h prior to graft placement and for 2 weeks postoperatively. Distal anastomotic intimal hyperplasia (AIH) and luminal surface EC coverage were quantitated at the conclusion of a 16-week study period. Patency for Group I and Group II grafts were 90% and 55%, respectively (p = 0.07). Maximum AIH, defined as the maximum reduction of luminal cross-sectional area at the distal anastomosis, was not significantly different between Group I (13.1 +/- 8.0%) and Group II (15.1 +/- 7.3%) conduits. However, AIH was inversely related to the extent of luminal EC coverage (r = -0.6, p less than 0.05), thus greater endothelialization was associated with decreased AIH. These data support the idea that EC coverage of the luminal surface of prosthetic vascular grafts may limit the development of AIH.

Animals↗
PubMed1991

Absence of complement-mediated events after protamine reversal of heparin anticoagulation.

Protamine reversal of heparin anticoagulation is associated with adverse hemodynamic effects that may be attenuated with protamine pretreatment (PP). This study assesses the role of complement activation during these phenomena in adult cardiac surgery patients. Sixteen individuals undergoing cardiopulmonary bypass were given intravenous normal saline or protamine (2 mg/kg) as a randomized pretreatment prior to undergoing heparin anticoagulation (400 IU/kg), coronary artery revascularization, and subsequent reversal of the anticoagulated state with protamine (4 mg/kg). Blood pressure, pulmonary artery diastolic pressure (PAD), heart rate, and cardiac output (CO) were measured during and after pretreatment, prior to heparin reversal by protamine, and for 10 min after reversal. Total hemolytic complement (CH50), C3 conversion to C3b, C3a/C5a, platelet count, and white blood cell count (WBC) were also measured at the same time periods. No significant correlation existed between complement activation and hemodynamic events, as might have been evident by decreased CH50, increased C3 conversion to C3b, or elevations in C3a/C5a levels. PP significantly prevented the CO decrease occurring at 1 and 3 min following heparin reversal by protamine (-0.8 and -1.4 liters/min vs 0.1 and -0.2 liters/min, P less than 0.05 and P less than 0.01, respectively). Reversal hypotension was less with PP, although PAD fell equally in both groups. WBC decreases after heparin reversal were less after PP (-25% vs -7%, P = 0.06). These data support the conclusion that, contrary to earlier reports, adverse hemodynamic and hematologic responses accompanying protamine reversal of heparin anticoagulation do not appear to be correlated with activation of complement. In fact, those patients having the greatest C3a generation exhibited the least hemodynamic changes.

Adult↗
PubMed1991

Effect of controlled hemorrhage on tissue and serum cefazolin clearance.

Effects of blood loss on tissue and serum antibiotic levels were investigated in 30 New Zealand white rabbits. Studies were conducted over a 3.5-hr period after intravenous administration of cefazolin, 30 mg/kg, in control animals (Groups I and IV, n = 5 each) and animals having 50% (Groups II and V, n = 5 each) or 100% (Groups III and VI, n = 5 each) of their blood volume removed and replaced with either Ringer's solution (Groups I, II, and III) or rabbit whole blood (Groups IV, V, and VI) sufficient to maintain central venous pressures at baseline levels. Periodic samples of retroperitoneal fat, iliac artery, and serum were assayed for cefazolin concentration by disc diffusion. Decreased tissue antibiotic levels were observed in animals undergoing 100% blood replacement (Groups III and VI) compared to controls (Groups I and IV) in both fat (P less than or equal to 0.01) and artery (P less than or equal to 0.01) at 90 min. Decreased antibiotic serum half-life accompanying hemorrhage existed when comparing Group II to I (P less than or equal to 0.05), Group III to I (P less than or equal to 0.01), and Group IV to V (P less than or equal to 0.01). The increased antibiotic clearance related to blood loss in this study justifies reassessment of intraoperative dosing intervals. More frequent dosing may be required to maintain stable tissue and serum antibiotic levels during substantial operative hemorrhage.

Animals↗
PubMed1991

Clinical characteristics and surgical management of vascular complications in patients undergoing cardiac catheterization: interventional versus diagnostic procedures.

The purpose of this report is to define the clinical characteristics and outcome of surgical management of vascular complications after interventional cardiac catheterization and to contrast them to those after diagnostic cardiac catheterization. From October 1985 to December 1989, 101 patients were treated for 106 vascular complications after 1866 interventional and 5046 diagnostic cardiac catheterizations at the University of Michigan Medical Center. Interventional catheterizations resulted in 69 vascular complications in 64 patients (frequency 3.4%). The most common interventions included coronary angioplasty (34), of which 10 required percutaneous partial cardiopulmonary bypass, intraaortic balloon pump placement (14), and aortic valvuloplasty (11). Interventional catheter-related complications included hemorrhage (33), arterial thrombosis (18), pseudoaneurysm formation (12), catheter embolization (2), thromboembolism (2), as well as arteriovenous fistula, pseudoaneurysm, and arterial dissection (1 each). Fifteen of these 69 patients (24%) had suffered acute myocardial infarction just before their catheterization. Surgical repair was performed under local anesthesia in 70% of patients. Major vascular reconstructions were required in 9% of patients. Three percent of the involved lower extremities had to be amputated because of complications occurring after arterial puncture. Eight percent of the patients incurring vascular complications after interventional procedures died after operation. Diagnostic catheterizations resulted in 37 vascular complications in 37 patients (frequency 0.7%). In contrast to diagnostic cardiac catheterization, vascular complications after interventional cardiac catheterization occurred more frequently, were most often due to hemorrhage at the vascular access site, and occurred in high-risk, critically ill patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Small-caliber polyurethane and polytetrafluoroethylene grafts: a comparative study in a canine aortoiliac model.

In vivo stability of a new small-caliber polyurethane graft (n8) was assessed in a canine aortoiliac model and compared to that of a conventional expanded polytetrafluoroethylene (ePTFE) graft (n8). Six months following implantation, marked aneurysmal dilatation to 230 +/- 80% (mean +/- SD) of the original diameter occurred in polyurethane grafts, while dilatation to 110 +/- 8% of the original diameter occurred in ePTFE grafts (p less than 0.005). Interval patency was 75% for each graft type. Luminal thrombus affected 59% of polyurethane graft surfaces compared to 22% of ePTFE graft surfaces (p less than 0.01). Qualitative examination of representative sections of polyurethane conduits demonstrated thick inner capsules with numerous small islands of graft material surrounded by macrophages and bands of mature fibrous tissue, in contrast to the thinner neointima and limited anastomotic pannus ingrowth observed in ePTFE grafts.

Animals↗
PubMed1990

Long-term results of aortoiliac reconstruction.

To facilitate evaluation of new and evolving interventional strategies in the management of aortoiliac occlusive disease, the collective long-term experience with traditional operative reconstruction was reviewed. Endarterectomy, currently the procedure of choice for a limited number of patients with disease localized to the aorta and common iliac arteries, has demonstrated 10-year primary patency rates of 48%-77%. By comparison, prosthetic in situ replacement or bypass grafting, commonly performed for more extensive lesions and in the presence of aneurysmal degeneration or total occlusion of the aorta, has yielded 10-year primary patency rates of 62%-79%. Cumulative graft patency can often be extended by means of thrombectomy, thrombolysis, and repair of thrombosed graft limbs, with 20-year extended cumulative patency rates of 49%-68%. The long-term success of operative reconstruction is highly dependent on the extent of coexistent peripheral occlusive disease, with progression of outflow disease representing the single most important factor associated with thrombosis of endarterectomy sites or prosthetic bypass grafts. Further improvements in long-term outcome for all modes of intervention in aortoiliac occlusive disease require increased attention to the minimization of risk factors associated with the underlying atherosclerotic disease process.

Angioplasty, Balloon↗
PubMed1990

Relief of mesenteric ischemia in type III aortic dissection with percutaneous fenestration of the aortic septum.

Subacute mesenteric ischemia developed 2 months after initial presentation in a patient with a type III aortic dissection. Percutaneous transfemoral fenestration of the septum between the true and false lumens resulted in resolution of clinical, angiographic, and manometric signs of ischemia. Continued expansion of the false lumen required aortic resection and graft replacement of the distal thoracic and abdominal aorta 2 months after the fenestration procedure. At operation, the fenestration site appeared as a 2-cm horizontal tear in the aortic septum, free of adherent thrombus and unrelated to expansion of the false lumen.

Aortic Dissection↗
PubMed1989

Effects of thromboxane synthetase inhibition on patency and anastomotic hyperplasia of vascular grafts.

The efficacy of a thromboxane synthetase inhibitor (U-63,557A, Upjohn) in promoting early patency and inhibiting anastomotic intimal hyperplasia in ePTFE grafts was compared to that of acetylsalicylic acid (ASA) in a canine model. Animals were started on ASA 5 gr po qd (Group I, n = 12) or U-63,557A 10 mg/kg po bid (Group II, n = 12) 1 day before placement of bilateral 5-mm-i.d., 13- to 16.5-cm-long ePTFE aortoiliac grafts and continued on the medication for the 16-week study. Six dogs in each group received autologous endothelial cell-seeded grafts, while the other six received unseeded grafts. Patency was determined weekly by assessment of femoral pulses. At the conclusion of the study anastomotic intimal hyperplasia was measured on serial sections through the distal anastomosis using a computer-linked digitizer. In Group I the patencies of seeded and unseeded grafts were not significantly different, being 100 and 83%, respectively. Furthermore, luminal narrowing due to intimal hyperplasia was not significantly different being 9.1 +/- 7.6% (chi +/- SD) in seeded grafts and 8.8 +/- 8.1% in unseeded grafts. On the other hand, in Group II the seeded grafts had significantly improved patency when compared to the unseeded grafts (83% vs 33%, P less than 0.05) and less luminal narrowing (11.4 +/- 11.1% vs 21.9 +/- 19.5%, P less than 0.01). Although U-63,557A administration promoted patency of unseeded grafts compared to no antiplatelet medication (0% patency), it was significantly less effective than ASA in improving patency (P less than 0.05) and inhibiting luminal narrowing (P less than 0.01).

Anastomosis, Surgical↗
PubMed1988

Systemic effects of prosthetic vascular graft implantation.

The effect of prosthetic vascular graft implantation on systemic complement activation, as well as leukocyte and platelet counts, was studied in rabbits. Animals underwent aortic clamping and declamping alone (group I) or with implantation of an externally supported PTFE graft (group II) or preclotted knitted Dacron graft (group III). Fifteen minutes after declamping, mild activation of complement reflected as a fall in CH50 to 72% of preoperative baseline values was observed in group I animals. Comparatively greater activation was seen in group II (43% baseline) and group III (28% baseline) animals. The differences between groups I and II (p less than 0.05) and I and III (p less than 0.01) were significant. The drop in platelet count was greater in group II (66% baseline) and group III (53% baseline) animals compared with group I (86% baseline). Neutrophil counts decreased in group I animals (75% baseline), but, again, this fall was more marked in group II (35% baseline) and group III (43% baseline) animals. The difference between groups I and II was significant (p less than 0.05). Similarly, monocyte count decreased in group I animals (80% baseline), which was also more marked in group II (32% baseline) and group III (31% baseline) animals. The differences between group I and groups II and III were significant (p less than 0.05 for each). These trends persisted throughout the first postoperative hour. These results suggest that the blood-surface interactions produced systemic effects in vivo.

Animals↗