Jeffrey M. Reilly

Doxycycline inhibition of aneurysmal degeneration in an elastase-induced rat model of abdominal aortic aneurysm: Preservation of aortic elastin associated with suppressed production of 92 kD gelatinase

PURPOSE Increased local production of matrix metalloproteinases (MMPs) is a potential mechanism underlying structural protein degradation in abdominal aortic aneurysms (AAA). With an elastase-induced rodent model of AAA, we determined whether pharmacologic treatment with an MMP-inhibiting tetracycline might limit the development of experimental AAA in vivo. METHODS Forty-eight Wistar rats underwent a 2-hour perfusion of the abdominal aorta with 50 U porcine pancreatic elastase and were then treated with either subcutaneous doxycycline (25 mg/day; n=24) or saline solution vehicle (n=24). Aortic diameter was measured before and after elastase perfusion was performed and before the rats were killed at 0, 2, 7, or 14 days, and AAAs were defined as an increase in aortic diameter to at least twice that before perfusion. At death the aortic tissues were either perfusion-fixed for histologic evaluation or extracted for substrate zymographic evaluation. RESULTS Aortic diameter was not different between groups at 0 or 2 days, but it was significantly less in animals treated with doxycycline at both 7 and 14 days (mean+/-SEM, p<0.01). After day 2 the incidence of AAA was reduced from 83% (10 of 12 rats treated with saline solution) to 8% (1 of 12 animals treated with doxycycline). By histologic assessment doxycycline prevented the structural deterioration of aortic elastin without decreasing the influx of inflammatory cells. Increased aortic wall production of 92 kD gelatinase observed in a saline solution-treated control group was markedly suppressed in animals treated with doxycycline. CONCLUSIONS Treatment with an MMP-inhibiting tetracycline inhibits the development of experimental AAA in vivo. This inhibition may be due to selective blockade of elastolytic MMP expression in infiltrating inflammatory cells. Additional experiments, however, are necessitated to fully delineate this process.

Preoperative treatment with doxycycline reduces aortic wall expression and activation of matrix metalloproteinases in patients with abdominal aortic aneurysms

PURPOSE Matrix metalloproteinases (MMPs) are considered to play a central role in the pathogenesis of abdominal aortic aneurysms (AAAs). Doxycycline (Dox) has direct MMP-inhibiting properties in vitro, and it effectively suppresses the development of elastase-induced AAAs in rodents. The purpose of this study was to determine if treatment with Dox suppresses MMPs within human aneurysm tissue and to elucidate the molecular mechanisms underlying this effect. METHODS Aneurysm tissues were obtained from 15 patients with an AAA, eight of whom had been treated with Dox before surgery (100 mg orally twice a day for 7 days). Protein extracts were examined by means of gelatin zymography and immunoblot analysis, and RNA was examined by means of reverse transcription-polymerase chain reaction (RT-PCR). The effects of Dox on MMP production were further examined in human THP-1 mononuclear phagocytes in vitro. RESULTS No detectable difference was found between groups by using substrate zymography as a means of assessing total MMP activity, but Dox treatment was associated with a slight (24.4%) reduction in the activated fraction of 72-kDa gelatinase (MMP-2; P <.05). In contrast, a 2.5-fold reduction in the amount of extractable 92-kDa gelatinase (MMP-9) protein in Dox-treated patients was revealed by means of immunoblot analysis (P <.05). Also, a 5.5-fold (81.9%) reduction in MMP-9 messenger RNA (mRNA) in Dox-treated patients was demonstrated by means of quantitative competitive RT-PCR (mean +/- SE, mol MMP-9/mol beta-actin: 1.3 +/- 0.5 vs 7.2 +/- 3.1; P <.04). There was no significant difference between groups in the relative expression of MMP-2 protein or mRNA. In cultured THP-1 monocytes stimulated with phorbol ester, the expression of MMP-9 protein and mRNA were both decreased after exposure to relevant concentrations of Dox in vitro. CONCLUSION In addition to its recognized effects as a direct MMP antagonist, Dox may influence connective tissue degradation within human aneurysm tissue by reducing monocyte/macrophage expression of MMP-9 mRNA and by suppressing the post-translational processing (activation) of proMMP-2. Through this complementary combination of mechanisms, treatment with Dox may be a particularly effective strategy for achieving MMP inhibition in patients with an AAA.

Transabdominal versus retroperitoneal incision for abdominal aortic surgery: Report of a prospective randomized trial ☆ ☆☆ ★

PURPOSE The purpose of this study was to perform a randomized, prospective trial that compares the transabdominal with the retroperitoneal approach to the aorta for routine infrarenal aortic reconstruction. METHODS From August 1990 through November 1993, patients undergoing surgery for abdominal aortic aneurysm (AAA) disease or aortoiliac occlusive disease (AIOD) were asked to participate in a randomized trial comparing the transabdominal incision (TAI) to the retroperitoneal incision (RPI) for aortic surgery. One hundred forty-five patients were randomized, with 75 (41 with AAA and 34 with AIOD) in the TAI group and 70 (40 with AAA and 30 with AIOD) in the RPI group. There were no significant differences between the groups in terms of age, sex, postoperative pain control (epidural vs patient-controlled analgesia), or comorbid conditions, except for a higher incidence of chronic obstructive pulmonary disease in the TAI group (21 vs 8 patients). RESULTS The incidence of intraoperative complications was similar for both groups. After surgery, the incidence of prolonged ileus (p = 0.013) and small bowel obstruction (p = 0.05) was higher in the TAI group. Overall, the RPI group had significantly fewer complications (p < 0.0001). The overall postoperative mortality rate (two deaths) was 1.4%, with both occurring in the TAI group (p = 0.507). The RPI group also had significantly shorter stays in the intensive care unit (p = 0.006), a trend toward shorter hospitalization (p = 0.10), lower total hospital charges (p = 0.019), and lower total hospital costs (p = 0.017). There was no difference in pulmonary complications (p = 0.71). In long-term follow-up (mean 23 months), the RPI group reported more incisional pain (p = 0.056), but no difference was found in incisional hernias or bulges (p = 0.297). CONCLUSIONS We conclude that the RPI approach for abdominal aortic surgery is associated with fewer postoperative complications, shorter stays in the hospital and intensive care unit, and lower cost. There is, however, an increase in long-term incisional pain. Current methods of postoperative pain control seem to decrease the incidence of pulmonary complications.

Spontaneous closure of selected iatrogenic pseudoaneurysms and arteriovenous fistulae

PURPOSE We report our approach to the management of postcatheterization femoral artery pseudoaneurysms and arteriovenous fistulae in an attempt to determine the frequency of spontaneous resolution of selected lesions. METHODS We studied 196 pseudoaneurysms, 81 arteriovenous fistulae, and 9 combined lesions that were identified by duplex scan. Indications for immediate surgical repair included pseudoaneurysm greater than 3 cm, enlarging hematoma, pain, groin infection, nerve compression, limb ischemia, concomitant surgical procedure, and patient refusal or inability to comply with follow-up. All other lesions were observed. RESULTS One hundred thirty-nine patients underwent prompt surgical repair, and 147 patients were initially managed without operation. There were no limb-threatening complications associated with nonoperative management in this subset of patients. Eighty-six percent of the lesions being observed resolved spontaneously within a mean of 23 days, whereas 14% required surgical closure for a variety of reasons (at a mean of 111 days after the initial diagnosis). There was no statistically significant difference in the rate of spontaneous pseudoaneurysm closure (89%) as opposed to fistulae (81%) (p < 0.17). By life-table analysis, 90% of selected pseudoaneurysms had resolved by 2 months. Patients selected for observation underwent an average of 2.6 duplex scans per patient versus 1.4 scans per patient for those treated with immediate surgery (p < 0.01). CONCLUSION The natural history of stable pseudoaneurysms and arteriovenous fistulae is benign and frequently results in spontaneous resolution, which allows properly selected patients to be managed without operation.

Prostaglandin E2 synthesis and cyclooxygenase expression in abdominal aortic aneurysms

PURPOSE The purpose of this study was to evaluate the expression of prostaglandin E2 (PGE2) and the two cyclooxygenase isoforms (cox1 and cox2) in human abdominal aortic aneurysm (AAA) tissue. METHODS Ten specimens each of normal aortas and aneurysmal aortas were collected and used for histologic analysis and whole organ culture. An enzyme-linked immunosorbent assay for PGE2 was performed on the media from the aortic explant whole organ culture. An immunohistochemical analysis for PGE2 was performed, as was in situ hybridization for cox1 and cox2 on tissue sections. RESULTS PGE2 production of AAA specimens was found to be 67,287 +/- 27,303 pg/ml as compared with 1698 +/- 858 pg/ml for normal aortic specimens (p < 0.001). PGE2 was localized by immunohistochemical analysis to the inflammatory infiltrate in AAAs. Minimal expression was noted in normal aortas. Using in situ hybridization, little expression of cox1 was noted in either the normal or the AAA specimens. Cox2 was expressed by macrophage-like cells within the inflammatory infiltrate of the AAA specimens but was not significantly expressed in the normal aorta. CONCLUSION The expression of PGE2 is associated with the pathogenesis of human AAAs. Its expression is localized to macrophage-like cells within the inflammatory infiltrate and is controlled by the cox2 isoform of cyclooxygenase. Cox2 is, therefore, a potential target for pharmacotherapy of AAAs.

Abnormal expression of plasminogen activators in aortic aneurysmal and occlusive disease

PURPOSE AND METHODS Aortic aneurysms are characterized by the destruction of the extracellular matrix of the media, whereas occlusive disease involves excess matrix accumulation within the intima. Plasmin degrades extracellular matrix directly and indirectly by activation of latent metalloenzymes. To determine the expression of tissue- and urokinase-type plasminogen activators, immunoassay, fibrin autography, Northern analysis, and immunohistochemistry were performed on specimens of aneurysmal (n = 12), occlusive (n = 8), and healthy (n = 6) aorta. RESULTS Immunoassay of tissue-type plasminogen activator revealed 8.7 +/- 0.9 ng tissue-type plasminogen activator/mg extracted protein in aneurysmal aorta, 5.7 +/- 0.3 ng/mg in normal aorta, and 2.5 +/- 0.3 ng/mg in occlusive aorta (p < 0.05 for comparisons between all groups). No urokinase-type plasminogen activator antigen was detected by urokinase-type plasminogen activator immunoassay. Fibrin autography exhibited lytic activity at 64 kDa and 54 kDa attributable to tissue-type plasminogen activator and urokinase-type plasminogen activator. The vast majority of fibrinolysis was secondary to free tissue-type plasminogen activator and was greatest in aneurysmal disease and least in occlusive disease. There was only a small amount of lysis secondary to urokinase-type plasminogen activator. Expression of tissue-type plasminogen activator and urokinase-type plasminogen activators mRNA was comparable in aneurysmal and occlusive aortas. In contrast to occlusive disease, aneurysms had an inflammatory cell infiltrate characterized by the expression of urokinase-type plasminogen activator by specific mononuclear cells. Tissue-type plasminogen activator expression was evident in the intima of normal and diseased aorta and in the media of diseased aorta. CONCLUSION Differential expression of plasminogen activators within the arterial wall may contribute to the unique pathogenesis of aneurysmal and occlusive aortic disease.

Indomethacin inhibits expansion of experimental aortic aneurysms via inhibition of the cox2 isoform of cyclooxygenase

PURPOSE Cyclooxygenase, either the cox1 or cox2 isoform, controls synthesis of prostaglandin E2 (PGE2), which regulates expression of matrix metalloprotease-9 (MMP-9). PGE2 and MMP-9 are elevated in aortic aneurysms. The mechanisms and time course of the inhibition of aneurysm expansion with a nonspecific cyclooxygenase inhibitor, indomethacin, were determined in an animal model. METHODS Rats underwent aortic perfusion with saline (n = 40) as controls or with elastase. Elastase-treated animals received no treatment (n = 82) or received indomethacin (n = 73). Aortic diameters were determined at the time of aortic perfusion and when the rats were killed. The aortas were harvested and used for whole organ culture, substrate gel zymography, or histologic analysis. RESULTS The control group demonstrated little change in aortic diameter. All the elastase-only animals developed aneurysms (maximal aortic diameter, 5.27 +/- 2.37 mm on day 14). Indomethacin markedly decreased the rate of aortic expansion (maximum aortic diameter, 3.45 +/- 1.11 mm; P <.001 vs the elastase-only group). The enzyme-linked immunosorbent assay of aortic explant culture media showed that PGE2 synthesis paralleled aortic expansion, and indomethacin decreased PGE2 synthesis. Histologically, the aortic elastin architecture was destroyed in the elastase group, but was preserved with indomethacin treatment. In situ, hybridization for cox1 and cox2 showed that cox2, but not cox1, was expressed and was co-localized by immunohistochemistry to macrophages associated with the aortic wall. Decreased levels of MMP-9 activity with indomethacin were shown by means of substrate zymography. MMP-9 was also localized to macrophages. CONCLUSION Indomethacin attenuates aneurysm growth, and its effects are mediated via inhibition of the cox2 isoform of cyclooxygenase, which decreases PGE2 and MMP-9 synthesis.

Characterization of an Elastase from Aneurysmal Aorta Which Degrades Intact Aortic Elastin

Accumulating evidence suggests that abdominal aortic aneurysms (AAA) are due to a pathologic process which results in the destruction of aortic elastin and other matrix components. In this study, protein extractions were performed on both aneurysmal and normal aorta. Extracts were applied to frozen section of normal aorta elther alone or in combination with 10 mM ethylenediaminetetraacetic acid, recombinant tissue inhibitor of metalloproteases, 10 mM zinc, and 5 mM phenylmethylsulfonyl fluoride, under conditions where calcium was removed from the buffer. After incubation, the sections were stained for elastin and evaluated by computerized morphometry. Aneurysm extracts, only in the presence of calcium, showed significant elastolytic activity characterized by destruction of intact elastic lamellae that was inhibited by ethylenediaminetetraacetic acid, the recombinant metalloprotease inhibitor, and zinc. Phenylmethylsulfonyl fluoride showed no inhibitory activity. Healthy aortic extract showed no elastolytic activity. This inhibitory profile is consistent with a metalloenzyme. We conclude that aneurysmal aorta contains elastolytic activity that is secondary to a metalloenzyme which is not present in normal aorta. This activity may play a role in the destruction of the elastin matrix that is seen in AAAs.

Femoropopliteal Bypass for Claudication: Vein vs. PTFE

The vascular graft of choice for femoropopliteal bypass in patients with intolerable claudication is controversial. We retrospectively reviewed our experience with 239 patients suffering from claudication secondary to superficial femoral artery obstruction. Femoropopliteal reconstruction was performed with saphenous vein to the below-knee popliteal artery in 66 patients (BK-vein). Polytetrafluoroethylene (PTFE) was used in 128 patients as a bypass graft to the above-knee popliteal artery (AK-PTFE) and 45 patients had a PTFE graft to the below-knee popliteal artery (BK-PTFE). All patients were enrolled in a postoperative graft surveillance program with graft revision when appropriate. There was one perioperative death (0.4%). Primary patency at 5 years for AK-PTFE, BK-PTFE, and BK-vein was 58.0%, 55.0%, and 60.3%, respectively, and was not significantly different among the graft groups. Graft revision for failed/failing grafts resulted in 5-year secondary patency rates of 79.2% (AK-PTFE), 73.3% (BK-PTFE), and 74.4% (BK-vein). These secondary patency rates were not statistically different. Eventual conversion to a vein graft in patients initially treated with PTFE maximized patency in the femoropopliteal segment with 5-year patency rates of 84.6% and 93.0% for the AK-PTFE and BK-PTFE graft groups, respectively. Major leg amputation was necessary during the entire course of the study in eight (3.3%) patients. We conclude that long-term patency rates for femoropoliteal bypass in patients with intolerable claudication are similar for PTFE and autologous saphenous vein grafts.

Care of patients with deep venous thrombosis in an academic medical center : limitations and lessons

PURPOSE The primary goal of our study was to review the quality of care in patients with deep vein thrombosis,, with emphasis on identifying recurrent and remedial problems. Secondary goals were (1) to evaluate the use of the vascular laboratory and (2) to characterize our patient population with deep vein thrombosis and to identify a subset of patients with uncomplicated deep vein thrombosis who might be candidates for outpatient therapy in the future. METHODS A retrospective review was performed for all patients with deep vein thrombosis diagnosed with duplex scanning who were treated as inpatients from January 1993 through March 1993. RESULTS Fifty-four (16%) of 306 duplex scans were positive; 50 patients were treated as inpatients. Forty percent of patients had uncomplicated deep vein thrombosis that was potentially treatable on an outpatient basis. Mean time to obtain a therapeutic partial thromboplastin time was 22 hours (range 4 to 54 hours). Ten (20%) patients had inferior vena cava filters placed. The in-hospital mortality rate was 4%. Management problems occurred in 18 (36%) patients and included difficulty titrating anticoagulation, (10) physician failure to provide treatment after diagnosis, (five) and inappropriate use or complication of inferior vena cava filter placement (three). CONCLUSIONS Venous duplex examination is liberally but appropriately used. The primary remediable problem resulting in suboptimal management is difficulty titrating anticoagulation; inappropriate placement of inferior vena cava filters and physician failure to provide treatment also occur. In the future a substantial number of patients may be suitable for outpatient therapy.