Comparison of streptokinase, urokinase, and recombinant tissue plasminogen activator in an in vitro model of venous thrombolysis.

PURPOSE: Presumed differences in the thrombolytic activity and fibrinolytic specificity of the three commonly used thrombolytic agents, streptokinase, urokinase, and recombinant tissue plasminogen activator (rt-PA), are based on clinical study results, where variability renders meaningful comparisons difficult. An in vitro model of catheter-directed venous thrombolysis was used to compare the three agents. METHODS: Retracted iodine 125-radiolabeled clots that simulate those observed in the venous system were infused with thrombolytic agents at doses analogous to those used clinically. Perfusion with heparinized, whole human blood was undertaken for 60 minutes, measuring the efficacy of thrombolysis through serial quantification of radio tracer released into the circuit. Fibrinolytic specificity was determined by following decrements in perfusate fibrinogen concentration. RESULTS: Streptokinase was the agent associated with the slowest rate of clot lysis (p = 0.01 vs urokinase and rt-PA). Urokinase was associated with an intermediate rate of lysis but appeared to be the agent with the greatest degree of fibrinolytic specificity (p = 0.02 vs streptokinase, p = 0.05 vs rt-PA). Although rt-PA was associated with improved efficacy early in the perfusions, the differences between rt-PA and urokinase dissipated after 30 minutes. CONCLUSIONS: These laboratory observations suggest that urokinase may be the most appropriate agent for catheter-directed venous thrombolysis, offering an advantageous compromise between fibrinolytic specificity and thrombolytic speed.

Transfemoral endovascular aortic graft placement.

PURPOSE: The purpose of this study was to develop an endovascular system for transfemoral placement of straight aortic grafts and bifurcated aortoiliac grafts. METHODS: Both types of graft consist of barbed, self-expanding stents attached to a woven polyester fabric. Survival studies of straight-graft function were performed in six large mongrel dogs. Digital subtraction fluoroscopic equipment was used to guide insertion and record angiograms at 0, 1, and 3 months. Bifurcated grafts were inserted in an additional eight dogs, four with distal stents and four without. Straight grafts were inserted into six cadaveric aortas (five atherosclerotic and one aneurysmal; age 68.7 + 5.7 years) to assess stent attachment. RESULTS: Angiograms obtained immediately after straight-graft insertion showed placement to be within 4.6 + 1.6 mm of the intended level. Follow-up angiograms at 1 and 3 months showed no migration, no leakage, and patency of all six grafts. After bifurcated graft insertion there were no angiographic signs of perigraft leakage, with or without distal stents. The mean force required to displace straight grafts 10 mm from their original position in cadaveric aortas was 1388 + 127 g. CONCLUSION: These preliminary results show that straight and bifurcated endovascular grafts can be positioned accurately and securely in the abdominal aorta.

Neurologic events following carotid endarterectomy: prediction of outcome.

A total of 1572 carotid endarterectomies were performed at one institution between 1975 and 1987. One hundred five patients had early (< 3 weeks) neurologic events following carotid endarterectomy. Sixty-five patients had cerebral vascular accidents (CVAs) (4.1%), 14 patients had reversible ischemic neurologic deficits (0.9%), and 26 patients had transient ischemic attacks (1.7%). Eight patients died from CVAs (0.5%). The mean follow-up was 31 months (range 1 to 137 months) with a 5-year cumulative survival of 77%. The median time of occurrence of neurologic events was 4 hours. Ages, cerebral protection, patches, carotid occlusion time (mean 29 minutes), gender, and status of the contralateral carotid arteries were not predictors of outcome. Death from neurologic events increased significantly in patients who had preoperative CVAs compared with patients with preoperative transient neurologic deficits (p < 0.05). The time of occurrence of CVA after carotid endarterectomy affected outcome, and an early CVA (< 4 hours) was associated with a higher mortality at 30 days and at 4 months as a consequence of the initial CVA (p = 0.11). Patients who had a neurologic event more than 4 hours after surgery had a significantly better resolution of their symptoms (66%) compared with patients who had an early neurologic event (35%, p < 0.05). The long-term follow-up of the surviving patients demonstrated an improvement in neurologic function in 75% of the CVA group (36/48) and 92% (76/83) of all patients who had neurologic events in long-term follow-up.

Laser angioplasty in peripheral vascular disease: symptomatic versus hemodynamic results.

Most early reports on the efficacy of laser angioplasty have used subjective symptoms rather than objective hemodynamic parameters to evaluate clinical results. We reviewed our experience with hot tip laser-assisted balloon angioplasty in 99 occluded or stenotic arterial segments during 80 procedures in 71 patients, ranging from the aortic bifurcation to the tibial-peroneal trunk. Initial failure to successfully recanalize occluded or stenotic segments occurred in 13 instances (16%). Forty-one procedure-related complications occurred in 31 patients (39%). Functional results were evaluated by use of life-table methods on the basis of symptomatic versus hemodynamic improvement. Cumulative patency rates for symptomatic and hemodynamic improvement were 91% and 64% at 1 month, 71% and 48% at 6 months, and 57% and 34% at 1 year, respectively. These data suggest that symptomatic improvement alone gives a misleadingly high estimate of the efficacy of laser angioplasty when compared with more objective hemodynamic criteria (p less than 0.005). Hemodynamic success was more likely in aortoiliac lesions than femoropopliteal lesions (58% vs 18% at 1 year, p less than 0.01). Hemodynamic parameters should be used to evaluate the success of laser angioplasty, which in its present form, is associated with frequent complications and poor long-term success.

Factors determining survival after ruptured aortic aneurysm: the hospital, the surgeon, and the patient.

The 10-year experience of a single community was reviewed and a multivariate analysis was performed to determine the relative importance of clinical and environmental factors in mortality after ruptured abdominal aortic aneurysm resection. Ruptured aneurysms were repaired in 243 patients in six area hospitals (one university, five community) by 25 surgeons (16 vascular, 9 general). Overall, 30-day mortality was 55% (133/243). Although the mortality by hospital ranged from 44% to 68%, these differences were not statistically significant. However, significant variations occurred in the mortality rates of individual surgeons, ranging from 44% to 73%. The mortality rate for the vascular surgeons was less than that of the general surgeons, 51% versus 69% (p less than 0.05). Clinical factors were evaluated, and the most significant parameters were systolic blood pressure, presence of chronic obstructive lung disease, and history of chronic renal insufficiency. These results support the implication that the degree of specialization of the surgeon and the preexisting health of the patient are the most important determinants of survival after ruptured abdominal aortic aneurysm. The size and sophistication of the hospital appear to be less influential factors.

Differential effects of a gram-negative and a gram-positive infection on autogenous and prosthetic grafts.

A canine model was developed to study the differential response of a gram-negative and a gram-positive bacterial infection on autogenous and prosthetic grafts. After replacing segments of the femoral arteries of 15 dogs with autogenous vein in one groin and polytetrafluoroethylene in the contralateral groin, 10(8) colony-forming units of nonmucin-producing Staphylococcus epidermidis (five dogs), Pseudomonas aeruginosa (five dogs), or sterile saline solution (five dogs) were directly inoculated onto the grafts. The grafts were examined 7 to 10 days after implantation. None of the control dogs exhibited inflammatory signs, and no grafts or anastomoses disrupted. S. epidermidis was unrecoverable from either graft material in any of the animals, although histologic evaluation confirmed neutrophils and bacteria in four of five animals in the vein and polytetrafluoroethylene groups. No dog inoculated with S. epidermidis had graft or anastomotic disruption. By contrast, P. aeruginosa was recovered from both types of grafts in all inoculated animals. Neutrophils, bacteria, and microabscesses were observed in all of these animals. In addition, three of five polytetrafluoroethylene grafts and all five vein grafts disrupted either at the anastomoses or in the body of the vein graft. Therefore S. epidermidis is a less virulent organism that may persist in graft walls despite negative cultures, whereas P. aeruginosa is a highly virulent organism that can disrupt native artery, vein grafts, and anastomoses. The graft material appears to be less important than the bacteria in determining the outcome of infection.

Limb-threatening ischemia in the medically compromised patient: amputation or revascularization?

The clinical courses of 362 patients with threatened limbs, seen over a 25-year period, were reviewed. Below-knee amputation was elected in 158 patients and infrainguinal revascularization in 204 patients. Patients were excluded from the study if amputation was chosen on the basis of arteriographic findings, diffuse infection, or extensive tissue loss. In an effort to compare the two treatment modalities in a minimally biased fashion, patients were stratified into three classes on the basis of the Goldman Multifactorial Index of Cardiac Risk and the American Society of Anesthesiology classification. Within each class, patients treated with amputation and with bypass were comparable with respect to age, sex, severity of ischemia, and anesthetic technique. Patients who underwent revascularization had a lower perioperative mortality rate (p less than 0.05), a shorter length of hospital stay (p less than 0.05), and an increased long-term survival rate (p less than 0.05) than the medically matched subgroup of patients who underwent amputation. Patients in the revascularization group were more successful in regaining ambulatory abilities than patients in the amputation group (p less than 0.01). These differences were most significant as the degree of medical compromise increased. Although medically compromised patients have frequently been denied revascularization on the basis of presumed increases in surgical risk and decreased long-term survival, the data appear to suggest that it is precisely the patients of this group who appear to benefit the most from attempts at limb salvage.

Detection of occult colonic ischemia during aortic procedures: use of an intraoperative photoplethysmographic technique.

A photoplethysmographic technique was used in 30 consecutive patients who had abdominal aortic reconstruction to assess colonic viability intraoperatively. A sterile pulse oximeter probe was used to measure arterial pulsatility and transcolonic oxygen saturation (TCOS) in the proximal, midportion, and distal sigmoid colon before and after the reconstruction. No attempt at inferior mesenteric revascularization was made, irrespective of the photoplethysmographic results. The status of the colon was assessed between the third and sixth postoperative day by a colonoscopist unaware of the intraoperative data. Before the reconstructive procedure photoplethysmography displayed pulsatile flow in all patients with a mean TCOS of 95% +/- 0.4%. After reconstruction, 28 patients (93%) demonstrated unchanged pulsatility with mean TCOS of 94% +/- 0.4%. Despite ligation of a patent inferior mesenteric artery in 10 of these patients, all 28 had normal colonoscopic examinations. By contrast, two patients (6.7%) had a loss of photoplethysmographic pulsatility with unmeasurable TCOS. Both of these patients had ligation of an initially patent inferior mesenteric artery and demonstrated evidence of ischemic mucosal changes at colonoscopy. Intraoperative colonic photoplethysmography represents an easily performed, accurate method for predicting colonic viability. A loss of pulsatility suggests inadequate postreconstructive colonic perfusion and mandates revascularization of the inferior mesenteric artery.

High-risk aortic aneurysm repair with partial cardiopulmonary bypass.

Two patients with severe cardiac dysfunction and measured left ventricular ejection fractions of 18% and 20% underwent aneurysm repair with the use of femoral vein--femoral artery partial cardiopulmonary bypass. While the aorta was clamped, blood was withdrawn through the venous cannula, and oxygenated blood was delivered to the legs through the arterial cannula. This procedure allowed clamping and unclamping of the aorta to proceed without hemodynamic fluctuation. Intraoperatively, cardiac output, mean arterial pressure, pulmonary artery diastolic pressure, right atrial pressure, pulmonary capillary wedge pressure, and systemic vascular resistance were measured. Both patients recovered, which indicates that this technique may be safely undertaken in the severely compromised patient with cardiac disease.

Giant cell arteritis in a 20-year-old black man: a cause of intermittent calf claudication.

Giant cell arteritis in a young black man is an extremely unusual occurrence. A 20-year-old black man came for treatment of bilateral leg claudication that had been present for a 2-month period. His medical and angiographic evaluation led to an arterial biopsy that demonstrated giant cell arteritis. The patient was treated with corticosteroids and his condition has subsequently improved. Unusual variants of giant cell arteritis are discussed.