Endovenous laser ablation of varicose veins with the 1470 nm diode laser using a radial fiber – 1-year follow-up

Background:

Endovenous laser ablation is one of the most accepted treatment options for insufficient great and small saphenous veins. The aim of this study was to investigate the long-term efficacy and safety of the radial fiber (ELVeS-radial kit™) for the 1470 nm diode laser in a 1-year follow-up.

Methods:

A total of 308 lower limbs with primary insufficiency of great and small saphenous veins or insufficient tributaries were included in the prospective observational cohort study. The primary efficacy endpoint of the study was ultrasonographic proven elimination of venous reflux after at least 1 year. Secondary efficacy and further safety end points after 1 year were as follows: (1) sonographic exclusion of recanalization of the treated vein segments, (2) deep vein thrombosis, clinical pulmonary embolism or superficial vein thrombosis as defined by objective testing, (3) death from any cause, (4) persistent clinical complaints such as pain and paresthesia, (5) recurrent varicose veins. Patient satisfaction was assessed using a CIVIQ-2 questionnaire after 1 year.

Results:

Follow-up could be completed in 91.2% of the patients. Excellent efficacy numbers with 99.6% occlusion of the treated varicose veins as elimination of reflux could be demonstrated. After 1 year, 96% of the treated veins disappeared completely sonographically; one recanalization was observed. No deep vein thrombosis or pulmonary embolism occurred, three superficial vein thrombosis were diagnosed in follow-up examinations. Four patients died, not related to pulmonary embolism. No persistent pain or paresthesia occurred in the follow-up. Recurrent varicose veins were diagnosed in 10 patients (2.81%).

Conclusion:

One-year follow-up showed that endovenous laser treatment of varicose veins with 1470 nm diode laser using the radial fiber is highly effective, also regarding in a 1-year follow-up.

[Cardiology quality assessment in Germany--pro and contra]

The German National Institute for Quality in Healthcare has also developed a program of external quality assessment in the field of cardiology. Hospitals are committed to collect certain data of diagnostic coronary angiography, percutaneous coronary interventions and pacemaker implantations. If statistical abnormalities are observed a so called structured dialogue is implemented. The responsible physicians of the hospitals are asked to comment possible quality deficits. Appointed members of quality commissions examine the answers and can invite the responsible physicians for interviews or also visit the hospital. However the validity of the quality data is problematic, because audits or check-ups of quality assessment in place are lacking. Therefore the results should not be misused for a comparison or ranking of hospitals with each other. As long as the validity of the quality assessment has not been improved, the results should also not be accessible for other parties, such as health insurances.

Die Bedeutung der Cholesterinsenkung bei Patienten nach aortokoronarer Bypassoperation

Patients with aortocoronary bypass surgery generally have a severe, advanced coronary atherosclerosis. An intensive risk-factor management should be of special importance in these patients. However, cholesterol treatment goals are the same for operated or non-operated patients with coronary artery disease. Effective cholesterol lowering does not only decrease the progression of atherosclerosis in native coronary vessels but also helps to prevent the development of atherosclerosis in venous bypass grafts. Clinical studies demonstrated that this leads to an improvement of clinical endpoints. Unfortunately we know from registries, that even in bypass patients recommended guidelines for cholesterol lowering are often not followed.

Optimierte Cholesterinsenkung

Ezetimibe is a recently developed compound, which inhibits intestinal cholesterol absorption. Because there are hints for an increase of cholesterol absorption during statin therapy, the combination of Ezetimibe with a statin seems to be appropriate. This dual approach -- inhibition of intestinal cholesterol absorption and hepatic cholesterol synthesis -- offers a very potent reduction of cholesterol. The combination of statins with Ezetimibe leads to a further reduction of LDL-cholesterol up to 12-21%. The dual inhibition causes a more effective reduction of LDL-cholesterol than a statin monotherapy. LDL treatment goals can be reached more easily, and possible side effects of otherwise necessary high doses of statins can be avoided. Clinical endpoint studies with Ezetimibe are underway.

[Prophylaxis of bacterial endocarditis]

An effective prophylaxis against bacterial endocarditis is necessary in patients at risk. In all medical specialities, a lack of information about the importance concerning an antibiotic prophylaxis of bacterial endocarditis remains. Among other institutions the American Heart Association has updated recommendations for the prevention of bacterial endocarditis in order to more clearly define when prophylaxis is or is not recommended, improve practitioner and patient compliance, and reduce cost as well as potential side effects.

[Risk of perioperative mortality and complications following biological aortic valve replacement in elderly patients: stented vs. unstented prostheses]

Recently published studies suggest that the hemodynamic advantage of stentless bioprostheses in comparison to stented bioprostheses positively influence the long-term survival after aortic valve replacement. However, the more complex and time consuming implantation technique may increase the risk of operative death. Between April 1996 and September 2000, 201 patients with the mean age of 75 +/- 5 years underwent aortic valve replacement (AVR) with a stentless Medtronic Freestyle Bioprosthesis (FP) and 166 patients with a mean age of 77 +/- 5 years received a stented Medtronic Mosaic Bioprosthesis (MP). Patients requiring concomitant procedures other than coronary artery bypass grafting (CABG) were excluded. The operative mortality was 3.5% after AVR with the FP and 6% after AVR with the MP. Multiple logistic regression analysis considering the different patient populations revealed no increased risk of operative death after AVR with FB (p = 0.46). Previously heart operations (p = 0.046) and emergency operation (p = 0.022) were risk factors for operative death after AVR with the biological bioprostheses. The risk for postoperatively neurological impairment (p = 0.15) and other complications (p = 0.46) was furthermore not increased after implantation of a Freestyle stentless valve. The risk of delayed mobilization (p < 0.001) was 2.4-fold increased for patients after AVR with the Freestyle valve. A positive influence on survival due to the implantation of a stentless Freestyle valve could not be shown within the observed period. However, in spite of the more complex and time-consuming operation technique, the risk of operative death and postoperative complications is not increased after aortic valve replacement with the stentless FB.

[Risk of perioperative mortality and complications following biological aortic valve replacement in elderly patients: stented vs unstented bioprotheses]

Recently published studies suggest that the hemodynamic advantage of stentless bioprostheses in comparison to stented bioprostheses positively influence the long-term survival after aortic valve replacement. However, the more complex and time consuming implantation technique may increase the risk of operative death. Between April 1996 and September 2000, 201 patients with the mean age of 75 ± 5 years underwent aortic valve replacement (AVR) with a stentless Medtronic Freestyle Bioprothesis (FP) and 166 patients with a mean age of 77 ± 5 years received a stented Medtronic Mosaic Biopros thesis (MP). Patients requiring concomitant procedures other than coronary artery bypass grafting (CABG) were excluded. The operative mortality was 3.5% after AVR with the FP and 6% after AVR with the MP. Multiple logistic regression analysis considering the different patient populations revealed no increased risk of operative death after AVR with FB (p = 0.46). Previously heart operations (p = 0.046) and emergency operation (p = 0.022) were risk factors for operative death after AVR with the biological bioprostheses. The risk for postoperatively neurological impairment (p = 0.15) and other complications (p = 0.46) was furthermore not increased after implantation of a Freestyle stentless valve. The risk of delayed mobilization (p < 0.001) was 2.4-fold increased for patients after AVR with the Freestyle valve. A positive influence on survival due to the implantation of a stentless Freestyle valve could not be shown within the observed period. However, in spite of the more complex and time-consuming operation technique, the risk of operative death and postoperative complications is not increased after aortic valve replacement with the stentless FB.

[New strategies in the treatment of restenosis]

Twenty-three years after introduction of coronary angioplasty (PTCA), the inhibition of restenosis formation continues to be the major challenge for the interventional cardiologist. About 35-50% of all patients undergoing PTCA develop a renarrowing of the intravascular lumen within the following six months. The use of specific systemic drug therapy as well as different angioplastic methods (rotablation, atherectomy, laser angioplasty) all failed to significantly reduce restenosis. Local drug delivery and local gene therapy have only shown to be effective in animal experiments. Restenosis can be reduced by the use of stents; however restenosis can also develop within the stents. The treatment of choice for severe in-stent restenosis may become radiotherapy, which seems to be a promising tool also for other forms of restenosis.

Attenuated progression of coronary artery disease after 6 years of multifactorial risk intervention: role of physical exercise

BACKGROUND

It was the aim of this study to assess the long-term effects of physical exercise and low-fat diet on the progression of coronary artery disease. At the beginning of the study, 113 male patients with coronary artery disease were randomized to an intervention group (n=56) or a control group (n=57); 90 patients (80%) could be reevaluated after 6 years.

METHODS AND RESULTS

Patients in the intervention group (n=40) showed a reduction in total serum cholesterol (6.03+/-1.03 versus 5.67+/-1.01 mmol/L; P<.03) and triglyceride levels (1.94+/-0.8 versus 1.6+/-0.89 mmol/L; P<.005) and maintained their initial body mass index (26+/-2 versus 27+/-2 kg/m2; P=NS), but results were not statistically different from the control group (n=50) (total serum cholesterol, 6.05+/-1.02 versus 5.79+/-0.88 mmol/L; triglycerides, 2.25+/-1.28 versus 1.85+/-0.96 mmol/L [both P=NS]; body mass index, 26+/-2 versus 28+/-3 kg/m2 [P<.0001]). In the intervention group, there was a significant 28% increase in physical work capacity (166+/-59 versus 212+/-89 W; P<.001), whereas values remained essentially unchanged in the control group (165+/-51 versus 170+/-60 W; P=NS; between groups, P<.05). In the intervention group, coronary stenoses progressed at a significantly slower rate than in the control group (P<.0001). Energy expenditure during exercise was assessed in a subgroup; patients with regression of coronary stenoses spent an average of 1784+/-384 kcal/wk (approximately 4 hours of moderate aerobic exercise per week). Multivariate regression analysis identified only physical work capacity as independently contributing to angiographic changes.

CONCLUSIONS

After 6 years of multifactorial risk intervention, there is significant and persistent improvement in lipoprotein levels and physical work capacity, which results in a significant retardation of disease progression. These beneficial effects appear to be largely due to chronic physical exercise.

LDL stimulates chemotaxis of human monocytes through a cyclooxygenase-dependent pathway

Monocyte migration into the vessel wall is an early step in atherogenesis. Even though a number of chemotactic factors have been identified, the regulation of the chemotactic response is not clearly understood. As the release of arachidonic acid has been implicated in monocyte chemotaxis, we studied the influence of LDL, which can supply this fatty acid to cells, on the chemotactic mobility of monocytes. Migration of human monocytic U937 cells was abolished by a 30-hour incubation in medium containing lipoprotein-depleted 10% fetal calf serum. Thereafter, human VLDL, LDL, acetyl LDL, methyl LDL, HDL, free cholesterol, linoleic acid, oleic acid, or arachidonic acid was added. At the end of varying incubation periods (0.5 to 8 hours), chemotaxis, viability, and cellular cholesterol content were measured. In the same experimental setting we also studied the effects of the pharmacological agents chloroquine, indomethacin, and acetylsalicylic acid on LDL-mediated chemotaxis. Chemotaxis was restored by LDL in a dose- and time-dependent manner starting at concentrations as low as 5 micrograms/mL and at incubations as brief as 30 minutes. The other lipoproteins tested (VLDL, HDL, acetyl LDL, and methyl LDL) as well as free cholesterol had no comparable effect on chemotaxis. Viability and total cholesterol content did not differ among the groups. Simultaneous incubation of cells with chloroquine, indomethacin, and acetylsalicylic acid reduced restitution of chemotaxis by LDL by 71%, 82%, and 68%, respectively. In contrast, the agents had only slight inhibitory effects on the chemotactic mobility of serum-fed control cells. Incubation with linoleic acid showed a 60% restoration of chemotaxis, whereas arachidonic acid stimulated chemotaxis by 140% compared with the positive control. Preincubation of LDL with the monoclonal antibody MB47 directed against LDL resulted in a significantly reduced migratory response. The data suggest a novel cyclooxygenase-dependent regulatory mechanism of chemotaxis by LDL.

Predictive value of lipid profile for salutary coronary angiographic changes in patients on a low-fat diet and physical exercise program

In this study, 113 patients with modestly elevated levels of low-density lipoprotein cholesterol (<210 mg/dl) and coronary artery disease were randomized to an intervention group (n=56) or a control group (n=57). The intervention program consisted of daily exercise and a low-fat diet according to the American Heart Association's recommendation phase III; patients in the control group received "usual care" rendered by their private physician. After 1 year, complete data were available for all 92 patients (intervention: n=40; control: n=52) who underwent repeat coronary angiography. During the study course, patients in the intervention group showed an increase in apolipoprotein A-I(123 +/- 18 vs 129 +/- 20 mg/dl; p < 0.02) and apolipoprotein A-I/B (1.3 +/- 0.4 vs 1.5 +/- 0.4; p <0.01) and a decrease in apolipoprotein B (99 +/- 20 vs 89 +/- 18 mg/dl; p < 0.01), while apolipoprotein A-II remained unchanged (38 +/- 6 vs 38 +/- 6 mg/dl; p=NS). In the control group, there were no significant changes (apolipoprotein A-I, 124 +/- 17 vs 128 +/- 13 mg/dl; apolipoprotein A-II, 38 +/- 6 vs 39 +/- 6 mg/dl; apolipoprotein B, 100 +/- 21 vs 99 +/- 16 mg/dl; apolipoprotein A-I/B, 1.3 +/- 0.3 vs 1.4 +/- 0.5; all p=NS). As previously reported, there was a significant retardation of progression in patients in the intervention group (progression 23%, no change 45%, regression 32%) compared with the control group (progression 48%, no change 35%, regression 17%) (p < 0.05). Although retardation of progression was significantly associated with an increase in apolipoprotein A-I/B and a decrease in apolipoprotein B (p < 0.05), these gave way in multivariate analysis to changes in total cholesterol/high-density lipoprotein cholesterol, absolute levels of low-density lipoprotein cholesterol, and, in a subgroup of patients, to leisure-time physical activity (all p < 0.05). These data demonstrate that an intervention based on a low-fat diet and intensive physical exercise is capable of improving apolipoprotein levels, associated with retardation of progression of coronary artery disease. However, total cholesterol/high-density lipoprotein cholesterol and low-density lipoprotein cholesterol appear superior to apolipoproteins as metabolic markers for effective treatment in patients with coronary artery disease.

Fibrinogen promotes monocyte adhesion via a protein kinase C dependent mechanism

The accumulation of blood monocytes at sites of predilection of the vessel wall is an early cellular event of atherogenesis. Proteins of the vessel wall may facilitate monocyte adhesion and thus promote their recruitment. It has been shown that the relative content of extracellular fibrinogen increases during lesion development, and this study investigated the contribution of immobilized fibrinogen to monocyte adhesion and the underlying mechanism. Freshly isolated human blood monocytes were cultivated in serum-free RPMI 1640 in tissue culture wells precoated with albumin, fibrinogen, or fibrin. After 16 h the plates were washed and adherent cells enumerated. Immobilized fibrinogen enhanced monocyte adhesion more than 1.9-fold compared to immobilized albumin or fibrin (P < 0.05). Concomitant addition of the protein kinase C (PKC) inhibitors staurosporine or H7 suppressed monocyte adherence to immobilized fibrinogen but exerted no significant effect upon adhesion to any other surface tested. Stimulation of monocytes using phorbol myristate acetate resulted in increased binding of monocytes on fibrinogen but not on bovine serum albumin. When PKC activity was reduced through prolonged incubation with PMA for 16 h, a significant reduction of monocyte adhesion on fibrinogen was observed. Peptides containing RGD sequences, which have been demonstrated to be ligands for certain integrins, did not inhibit monocyte adhesion. The data suggest that fibrinogen promotes monocyte adhesion in vitro by a PKC-dependent mechanism. PKC appears to be important not only for the initial cell adhesion but also for sustained binding of monocytes to fibrinogen.

Impact of intensive physical exercise and low-fat diet on collateral vessel formation in stable angina pectoris and angiographically confirmed coronary artery disease

This randomized study was performed to assess the effects of > 3 hours of physical exercise per week and low-fat diet on collateral formation in nonselected patients with coronary artery disease (intervention group, n = 56). Results were compared with those of patients in a control group (n = 57), who received usual care by their private physicians. Coronary lesions were assessed by quantitative coronary angiography at the beginning and after 1 year of study (n = 92). As previously reported, after 1 year there was a significant retardation of progression of coronary artery disease in the intervention group as compared with the control group. In this study, evaluation of collateral formation revealed no significant difference between both groups, and changes in hemodynamic and metabolic variables or leisure time physical activity were not related to changes in collateral formation. Although progression of the disease was significantly related to an increase in collateral formation, regression was significantly related to a decrease in collateral formation (p < 0.00001). Because patients in the intervention group exercised for > 3 hours/week, and patients with regression of coronary artery disease even dedicated 5 to 6 hours to leisure time physical activity per week, these findings question whether an exercise program within the safety tolerance of patients will be able to induce coronary collateralization in the presence of regression of coronary artery disease.

Low-dose radioactive endovascular stents prevent smooth muscle cell proliferation and neointimal hyperplasia in rabbits

BACKGROUND

Restenosis induced by smooth muscle cell (SMC) migration and proliferation and neointimal thickening limits the clinical success of balloon angioplasty and stent implantation. In this study, the long-term effect of endovascular irradiation via low-dose radioactive stents on neointima formation was compared with conventional stent implantation in a rabbit model.

METHODS AND RESULTS

Palmaz-Schatz stents were made radioactive in a cyclotron. The stents had a very low activity (maximum, 35 microCi), and thus, manipulation did not require extensive radiation protection. One, 4, 12, and 52 weeks after the implantation of nonradioactive stents and radioactive stents in rabbit iliac arteries, neointimal thickening was analyzed by quantitative histomorphometry. Immunostaining for endothelial cell von Willebrand factor, macrophages, SMC alpha-actin, collagen type I, and proliferating cell nuclear antigen (PCNA) was performed to determine radiation-induced changes in the arterial wall. SMC proliferation was quantified by computer-assisted cell counting of PCNA-immunoreactive cells. Neointima formation was markedly suppressed by the implantation of radioactive stents in a dose-dependent fashion at all observed time points. At peak proliferative activity of SMCs 1 week after nonradioactive stent implantation, 30 +/- 2% of SMCs in the neointima were proliferating, compared with 0.5 +/- 0.1% of SMCs after implantation of stents with an initial activity of 35 microCi (P < .001). The neointima covering radioactive stents was characterized by decreased smooth muscle cellularity and increased extracellular matrix formation. Further, we observed a delayed endothelialization depending on the radiation dose. No difference in vascular thrombosis was found after nonradioactive and radioactive stent implantation.

CONCLUSIONS

The results of this study clearly indicate that low-dose radioactive endovascular stents potently inhibit SMC proliferation and neointimal hyperplasia in rabbits.

Fibrin-targeted recombinant hirudin inhibits fibrin deposition on experimental clots more efficiently than recombinant hirudin

BACKGROUND

Although the indirect thrombin inhibitor heparin and the more potent direct inhibitor hirudin are useful in preventing thrombosis, a substantial opportunity remains for improving the thrombus selectivity of thrombin inhibitors.

METHODS AND RESULTS

To explore the effect of targeting an antithrombin to the surface of a clot, we covalently linked recombinant hirudin to the Fab' (or IgG) of a monoclonal antibody (59D8) that selectively binds to an epitope on fibrin that becomes exposed only after thrombin cleaves fibrinopeptide B. Antibody-coupled hirudin bound to an immobilized peptide of the fibrin beta-chain amino-terminal sequence and inhibited the peptidolytic activity of thrombin more efficiently than free hirudin. Thrombin inhibition dependent on binding to immobilized fibrin monomer was enhanced 1100-fold (P < .0001). Hirudin-59D8 Fab' was 10 times more effective than hirudin in inhibiting fibrin deposition on experimental clot surfaces in fibrinogen solution (P < .0001) and human plasma (P < .0001). The more effective inhibition of thrombin by the conjugate was supported by significantly diminished concentrations of fibrinopeptide A in the plasma supernatant of the clot (P = .0001). Inhibition of clotting by an uncoupled mixture of hirudin and 59D8 Fab' was indistinguishable from that by hirudin alone, indicating that the conjugate's greater inhibitory activity was due to the covalent linkage between antibody and hirudin.

CONCLUSIONS

Fibrin-targeted hirudin (in comparison with unmodified hirudin) significantly reduces fibrin deposition on the surface of experimental clots.

Increased messenger RNA levels for low-density lipoprotein receptor and 3-hydroxy-3-methylglutaryl coenzyme A reductase in rat liver after long-term ethanol ingestion

Because long-term alcohol intake leads to severe alterations of cholesterol metabolism resulting in both elevated serum cholesterol levels and increased hepatic concentrations of cholesterol esters, we investigated the effect of long-term ethanol consumption on the hepatic messenger RNA (mRNA) content of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and low-density lipoprotein receptor, two major regulatory factors in cholesterol metabolism, and of apoprotein E. Twenty-four male Sprague-Dawley rats were pair-fed nutritionally adequate liquid diets containing 36% of total calories as either ethanol or isocaloric carbohydrates for 3 wk. In addition, the lipid content of the diets was varied, resulting in 35%, 17.5%, and 8.8% of total calories corresponding to a daily intake of cholesterol of between 1.2 and 6.3 mg/kg body wt. Although increasing dietary cholesterol intake resulted in a significant decrease of hepatic mRNA for low-density lipoprotein receptor and HMG-CoA reductase (p < 0.05), long-term ethanol consumption led to a significant increase of the mRNA for both proteins (p < 0.01), and this increase was predominantly obvious in animals fed a low-cholesterol diet. In contrast, mRNA content of apoprotein E was found to be significantly lower in livers from rats fed ethanol for a prolonged period of time as compared with controls (p < 0.01), and this effect was found to be still present, although less pronounced, after low cholesterol intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of primary hypercholesterolemia: fluvastatin versus bezafibrate

The effects of fluvastatin and bezafibrate on lipids, lipoproteins, and apoproteins (apo) were investigated in a multicenter randomized, double-blind, parallel-group study. After 8 weeks of strictly controlled (computer-based assessment) dietary stabilization, patients with primary hypercholesterolemia (low-density lipoprotein cholesterol [LDL-C] > or = 160 mg/dL; triglycerides < or = 300 mg/dL) were enrolled into a 6-week placebo phase. Altogether, 131 patients were randomized to receive either fluvastatin at 40 mg once daily (n = 64; mean age 53 years) or bezafibrate at 400 mg once daily (n = 67; mean age 52 years) for 12 weeks. Compliance with the diet was monitored (3-day food records) after 6 and 12 weeks. Fluvastatin led to significant reductions in LDL-C (-23%), total cholesterol (-17%), LDL-C/high-density lipoprotein cholesterol (HDL-C) (-24%) and apo B (-19%). Fluvastatin significantly increased LpA-I (+8%) and apo E (+20%). Bezafibrate produced significant reductions in LDL-C (-17%), total cholesterol (-13%), LDL-C/HDL-C (-24%), triglycerides (-28%), apo B (-15%), and LpA-I (-10%) and significantly increased HDL-C (+12%), apo A-I (+9%), apo A-II (+30%), apo E (+14%), and Lp(a) (+3%). No clinically notable increases in levels of liver enzymes or creatine phosphokinase were observed with either treatment. Both treatments were well tolerated. There was a low incidence of adverse events that tended to be mild and included headache, muscular pain, angina, and dyspepsia. The frequency of adverse events was similar in both treatment groups, and no significant differences in dietary behavior were observed. In conclusion, fluvastatin is a well tolerated 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor for the treatment of primary hypercholesterolemia. Effects of fluvastatin on LpA-I occur irrespective of changes in HDL-C.

The role of elastic recoil after balloon angioplasty of rabbit arteries and its prevention by stent implantation

Elastic recoil, neointima formation and vessel narrowing after balloon angioplasty or stent implantation were compared in 17 non-atherosclerotic New Zealand White rabbits. The implantation of a balloon-expandable Palmaz-Schatz stent was performed in one iliac artery and a balloon angioplasty alone was performed in the contralateral artery (n = 34 arteries). Quantitative histomorphometry was performed by a computer-assisted analysis 1 h and 4, 10 and 24 weeks after the initial procedure. The histological appearance of the neointima was similar to that of human restenosis. The amount of the neointima was increased within stented vessels as compared to balloon angioplasty alone (1.0 +/- 0.1 vs 0.4 +/- 0.1 mm2 at 4 weeks, P < 0.001). However, the neointimal lumen narrowing was smaller in the stented vessels due to persistent increase in vessel perimeter as compared to balloon angioplasty alone (16.5 +/- 0.9 vs 34.7 +/- 16.5% lumen narrowing at 4 weeks, P < 0.05). In conclusion, stent implantation enhances neointima formation as compared to angioplasty in non-atherosclerotic rabbits. The prevention of elastic recoil after stent implantation, however, reduces the neointimal lumen narrowing. This study supports clinical observations demonstrating lower restenosis rates after stent implantation compared to standard balloon angioplasty.

Effects of lipoprotein(a) on thrombolysis

Lipoprotein(a) (Lp(a)) and plasminogen share a high degree of structural homology. Therefore it has been suggested that elevated levels of Lp(a) may inhibit the profibrinolytic activity at the cell surface and increase the risk of thrombosis by competitive inhibition of plasminogen. In the present study we evaluated whether high levels of Lp(a) affect thrombolytic therapy in patients with acute myocardial infarction. Forty-one patients with acute myocardial infarction were treated with a combination of recombinant tissue-type plasminogen activator and human single-chain urokinase-type plasminogen activator. Coronary patency was assessed angiographically 90 min after initiation of treatment. Thrombolysis was successful in 30 and unsuccessful in 11 patients. Patients with high Lp(a) levels (> 25 mg/dl) (n = 9) responded equally well to thrombolytic therapy (8 of 9, patency 89%) as did patients with normal or low levels of Lp(a) (22 of 32, patency 70%, difference P > 0.1). The results demonstrate that high levels of Lp(a) do not influence thrombolysis in patients with acute myocardial infarction when low-dose pharmacologic concentrations of recombinant tissue-type plasminogen activator and human single chain urokinase-type plasminogen activator are applied in combination.

Cytokeratins 8 and 18 in smooth muscle cells. Detection in human coronary artery, peripheral vascular, and vein graft disease and in transplantation-associated arteriosclerosis

During development of atherosclerotic lesions, vascular smooth muscle cells (SMCs) undergo changes both phenotypically and in their cytoskeleton composition. An expression of cytokeratins 8 and 18 in SMCs in plaques of the human superficial femoral artery and of cytokeratin 8 in lesions of the aorta was recently described. Since cytokeratins are epithelial markers generally not found in normal adult vascular SMCs, we performed a detailed immunofluorescence microscopy study using a large panel of antibodies against the various cytokeratin polypeptides and other elements of the cytoskeleton. We included lesions of carotid, common and superficial femoral, iliac, and popliteal arteries; the abdominal aorta; and saphenous vein bypass grafts, as well as primary, restenotic, and transplantation-associated lesions of coronary arteries (n = 33). Cytokeratins 8 and 18 were present in myointimal cells of all pathological specimens. Colocalization with smooth muscle alpha-actin identified most cytokeratin-positive cells as SMCs. Only very few cells cosynthesized cytokeratin and desmin, whereas the majority of cytokeratin-positive cells were vimentin-positive. This pattern of cytoskeletal protein synthesis is similar to that found in some fetal and/or neonatal SMCs. These findings suggest that the synthesis of cytokeratins in a subset of SMCs of atherosclerotic lesions is a common phenomenon in coronary artery and peripheral vascular disease as well as graft disease and transplantation-associated arteriosclerosis and that the state of these SMCs is of a "dedifferentiated" fetal type.

Suppression of neointimal thickening and smooth muscle cell proliferation after arterial injury in the rat by inhibitors of Na(+)-H+ exchange

Replication of vascular smooth muscle cells is a key event in the pathogenesis of restenosis following angioplasty. Little is known about early biochemical events involved in the proliferation of smooth muscle cells following arterial injury. In the present study, the effect of Na(+)-H+ exchange inhibitors on neointima formation after balloon injury of the rat carotid artery was investigated. Neointima formation was quantified 14 days after injury by morphometric measurement of cross-sectional neointimal area and by fluorometric determination of DNA content. The specific Na(+)-H+ exchange inhibitor 3-methylsulfonyl-4-piperidino-benzoyl guanidine mesylate (Hoe 694) dose-dependently reduced neointimal area and DNA content, the latter finding indicating a true antiproliferative effect. The structurally different Na(+)-H+ exchange blocker 5-(N-ethyl-N-isopropyl)amiloride hydrochloride had comparable inhibitory effects on neointimal area and DNA content, whereas 5-methylsulfonyl-2-piperidino-benzoyl guanidine hydrochloride, a position isomer of Hoe 694 lacking Na(+)-H+ exchange blocking properties, did not suppress neointima formation. The effect of Na(+)-H+ exchange blockers on neointima formation depended on the duration of drug application. Maximal suppression was achieved only when Hoe 694 was applied throughout the entire experiment for 14 days. This inhibitory effect of Na(+)-H+ exchange blocker application for the first 2 weeks following injury lasted for 2 months. In conclusion, the results of the present study reveal a potential role of Na(+)-H+ exchange for smooth muscle cell proliferation in vascular disease.

[Thrombolytic therapy of acute myocardial infarct--current status and new developments]

Timely initiation of thrombolytic therapy can achieve coronary reperfusion, a reduction in infarct size, a preservation of left ventricular function and a reduction in mortality. It is therefore an established procedure in acute myocardial infarction. The major drawback is an increased rate of bleeding. As a consequence thrombolytic therapy is at present withheld from many patients with contraindications. Other problems include relative inefficacy of presently available thrombolytic agents and early reocclusion of primarily successfully reperfused vessels. New approaches to optimize the risk/benefit ratio for the patient and to make thrombolytic therapy available to more patients include new antithrombin and antiplatelet agents as adjunctive therapy, synergistic combinations of plasminogen activators, mutants of t-PA and prourokinase, chimeric molecules and antibody-targeted thrombolysis.

Autoradiographic analysis of the distribution of 125I-tyramine-cellobiose-LDL in atherosclerotic lesions of the WHHL rabbit

It is well established that plasma lipoproteins enter the artery wall and play a role in the atherogenic process. However, it is still unclear where within developing atherosclerotic lesions lipoproteins accumulate and which arterial cells participate in the metabolism of these lipoproteins. For this reason, light and electron microscopic autoradiograms were prepared from sections of lesioned aortas of Watanabe heritable hyperlipidemic (WHHL) rabbits 44 hours after injection of 125I-tyramine cellobiose-low density lipoprotein (TC-LDL). After uptake of 125I-TC-LDL and intracellular degradation of the LDL protein, the nondegradable TC ligand remains trapped and thus demarcates the cells participating in the degradation of LDL. Results of other studies indicate that 48 hours after injection into WHHL rabbits, about one half of the 125I label present in lesions represents accumulated degradation products while the remaining 125I label is present as intact 125I-TC-LDL. The distribution of autoradiographic silver grains was analyzed at low resolution in fatty streaks, transitional lesions, and advanced atheroma. In all cases, the majority of silver grains were associated with superficially located subendothelial macrophage-derived foam cells. In more advanced lesions, labeling was predominant in foam cells situated within the lateral margins of the lesions. Morphometric quantification of the distribution of silver grains in electron photomicrographs of fatty streaks from two young WHHL rabbits strongly supported the data obtained at the light microscopic level. In early fatty streaks from the aortic arch and the thoracic and abdominal aortas, subendothelial macrophage-derived foam cells contained a high proportion of the silver grains (40-60% of the total) and accounted for between 30% and 40% of the lesion volume. In contrast, smooth muscle cells in the lesions contained only 7-10% of the total silver grains and accounted for approximately 20% of the lesion volume. Endothelial cells contained the most silver grains on a per-unit-volume basis by occupying only 1-2% of the lesion volume. However, the endothelium contained less than 5% of the total grains in lesions. The remaining silver grains (25-45%) were associated with the extracellular matrix, which constituted between 40% and 50% of the lesion volume. These data indicate that in the WHHL rabbit, subendothelial macrophage-derived foam cells avidly accumulate and metabolize LDL despite having few functional LDL receptors.

Lipid levels in monocytes of patients with moderate hyperlipoproteinemia

Recent studies suggest that circulating blood monocytes may serve as a lipid clearance system in early atherosclerotic lesions. To evaluate the influence of moderate hyperlipoproteinemia on monocyte lipid concentrations, we measured fasting serum and monocyte lipid levels in 7 healthy individuals, in 7 patients with primary hypercholesterolemia and in 17 patients with secondary dyslipidemia due to chronic renal failure; 10 of these patients were treated by hemodialysis (HD) and 7 patients by continuous ambulatory peritoneal dialysis (CAPD). The hypercholesterolemic patients had elevated serum levels of total cholesterol, LDL-cholesterol and apolipoprotein (apo) B, but normal plasma triglycerides. Patients on dialysis had elevated serum levels of triglycerides, serum cholesterol (CAPD only) and VLDL- and LDL-cholesterol (CAPD only) and apo B (CAPD only), whereas HDL-cholesterol and apo A-I levels (HD only) were decreased. In monocytes, we measured the content of free cholesterol (FC), cholesteryl esters (CE) and triglycerides (TG). The normal mean intracellular concentrations of FC, CE and TG were 48.3, 1.7 and 2.4 micrograms/mg cell protein, respectively. All monocyte lipid levels were similar in patients and controls, with the exception of a decreased content of FC (30.8 micrograms/mg) in monocytes of HD patients. We conclude that moderate increases in serum lipoprotein lipid levels are not associated with lipid accumulation in monocytes.

Differential low density lipoprotein receptor-dependent formation of eicosanoids in human blood-derived monocytes

We studied the ability of low density lipoproteins (LDLs) to provide arachidonic acid (AA) for eicosanoid biosynthesis in human blood-derived monocytes. When incubated in the presence of reconstituted LDL that contained cholesteryl [1-14C]arachidonate (recLDL-[14C]AA-CE), resting monocytes formed three labeled products of the prostaglandin (PG) H synthase pathway: 6-keto-PGF1 alpha, thromboxane B2, and PGE2. The amounts of these eicosanoids in response to recLDL-[14C]AA-CE were comparable to or exceeded those that were produced in response to the addition of 10 microM unesterified [1-14C]AA. By contrast, resting monocytes formed only small amounts of products of the 5-lipoxygenase pathway, leukotriene (LT) B4 and LTC4 from either recLDL-[14C]AA-CE or [14C]AA, indicating preferential utilization of AA in the PGH synthase reaction. However, they converted LDL-derived [14C]AA efficiently into LTB4 and LTC4, when they were first incubated with recLDL-[14C]AA-CE and subsequently stimulated with the chemotactic peptide N-formylmethionylleucylphenylalanine or the Ca2+ ionophore A23187. The classical LDL receptor pathway mediated the synthesis of all of the above eicosanoids from LDL but not from unesterified AA. These results demonstrate that the LDL receptor pathway preferentially promotes the synthesis of PGH synthase products in resting human blood-derived monocytes and that an additional mechanism is required to promote effective synthesis of 5-lipoxygenase pathway products from AA that originates in LDL cholesteryl esters.

[Type III hyperlipoproteinemia in monoclonal IgM gammopathy]

A 42-year-old woman, found to have increased blood-lipid levels, developed hand-line xanthomas 3 months later. She also had an increased erythrocyte-sedimentation rate and a type lambda monoclonal IgM abnormality. In the course of the following 4 years the IgM concentration rose (from 5.8 to 12.3 g/l) steadily and synchronously with those of the triglycerides (from 147 to 391 mg/dl) and cholesterol (from 212 to 380 mg/dl). During the entire period of observation the ratio of VLDL cholesterol and triglyceride concentrations was elevated (greater than 0.4; normal: less than 0.3). Division of the lipoprotein fractions pointed to a type III hyperlipoproteinaemia. She also had an abnormality of lipid metabolism on the basis of a genetic defect (apolipoprotein-E2 homozygotism), which only manifested itself when an additional factor, IgM paraproteinaemia, was present. Paraproteins thus apparently interfered with the breakdown of the lipoproteins. Neither bezafibrate in increasing doses (200-800 mg daily) with low-fat diet nor administration of lovastatin (20 mg twice daily) together with nicotinic acid (500 mg twice daily) were adequate treatment for this form of auto-immune hyperlipidaemia.

Cholesterol efflux from macrophages mediated by high-density lipoprotein subfractions, which differ principally in apolipoprotein A-I and apolipoprotein A-II ratios

High-density lipoprotein (HDL) was fractionated by preparative isoelectric focussing into six distinct subpopulations. The major difference between the subfractions was in the molar ratio of apolipoprotein A-I to apolipoprotein A-II, ranging from 2.1 to 0.5. The least acidic particles had little apolipoprotein A-II, were larger and contained the most lipid. The efflux capacity of the HDL subfractions was tested with mouse peritoneal macrophages and a mouse macrophage cell line (P388D1), either fed with acetylated low-density lipoprotein or free cholesterol. All the HDL subfractions were equally able to efflux cholesterol. The efflux was concentration dependant and linear for the first 6 h. The HDL subfractions bound with high affinity (Kd = 6.7-7.9 micrograms/ml) at 4 degrees C to the cell surface of P388D1 cells (211,000-359,000 sites/cell). Ligand blotting showed that all the HDL subfractions bound to membrane polypeptides at 60, 100, and 210 kDa. These HDL binding proteins may represent HDL receptors. In summary HDL particles, which differed principally in ratio of apolipoprotein A-I to apolipoprotein A-II behaved in a similar manner for both cholesterol efflux and cell surface binding.

Effects of lipoprotein (a) on success rate of thrombolytic therapy in acute myocardial infarction

Lipoprotein (a) [Lp(a)] and plasminogen share a high degree of homology as recently evidenced by amino acid and deoxyribonucleic acid analysis. As Lp(a) is enzymatically inactive, it has been suggested that high levels of Lp(a) may suppress the profibrinolytic activity at the cell surface and increase the risk for arteriosclerosis and thrombosis by competitive inhibition of plasminogen. The present study evaluated whether high levels of Lp(a) influence thrombolytic therapy in patients with acute myocardial infarction. Forty-one patients with acute myocardial infarction received a combination low-dose thrombolytic therapy with recombinant tissue-type plasminogen activator (rt-PA) and human single-chain urokinase-type plasminogen activator (scu-PA). This regimen did not induce plasminemia or a lytic state as indicated by well-maintained levels of fibrinogen. Coronary patency was assessed angiographically 90 minutes after initiation of treatment. Thrombolysis was successful in 30 and unsuccessful in 11 patients. Patients with high Lp(a) levels (greater than or equal to 25 mg/dl) (n = 9) responded equally well to thrombolytic therapy (8 of 9, patency 89%) as did patients with normal or low levels of Lp(a) (22 of 32, patency 70%, difference greater than 0.1). Lp(a) levels did not differ significantly between patients with successful and unsuccessful thrombolysis. Our results demonstrate that high levels of Lp(a) do not affect thrombolysis in patients with acute myocardial infarction when low-dose pharmacologic concentrations of rt-PA and scu-PA are applied in combination.

[Recurrent ventricular fibrillation in a patient with angiographically normal coronary arteries and intermittent ST segment elevation]

We report on a patient who was admitted to the hospital because of severe angina pectoris. During hospitalization extensive ECG alterations and intermittent ventricular fibrillation were observed. However, coronary angiography showed normal coronary arteries and left ventricular function. Treatment with high-dose nitrates and Ca-antagonists gradually improved the patient's clinical situation. Although a Prinzmetal angina seemed likely, a vasculitis of the coronary arteries could not be excluded with certainty. Therefore, additional corticoid therapy was administered to the patient. After 5 weeks the patient was discharged from the hospital without any pathological clinical symptoms.

Atypical type III hyperlipoproteinemia in a patient with Ig A myelomatosis

We studied a 58-year-old woman with severe therapy-refractory hyperlipidemia, xanthomatosis, and multiple myeloma (immunoglobulin A, lambda light chain). The lipid disorder became evident about half a year prior to the expression of myelomatosis. Clinical symptoms were similar to those found in classical type III hyperlipoproteinemia but the underlying metabolic defect was different from the one described in this primary dyslipoproteinemia. The patient has the heterozygous apolipoprotein E3/2 phenotype and her VLDL-cholesterol/serum-triglyceride ratio is unusually low at 0.05. Evidence is given that the hyperlipoproteinemia is due to an impaired catabolism of intermediate density lipoproteins probably because of a reduced hepatic triglyceride lipase activity.

Mobilization of stored triglycerides from macrophages as free fatty acids

Because many or most lipid-laden foam cells in atheromas and in xanthomas derive from macrophages, it is important to understand how they accumulate lipids and how they can divest themselves of lipids. The mobilization of stored triglycerides from macrophages was studied in cell cultures. Mouse resident peritoneal macrophages and J774 macrophages increased their triglyceride content six- to tenfold during a 24-hour incubation with free fatty acids complexed to albumin. Subsequent incubation in fresh medium containing free fatty acid-poor albumin was accompanied by a fall in cell triglyceride content (50% in 20 hours) and a corresponding increase in medium-free fatty acid. Release of free fatty acid was linear as a function of time, provided fresh medium was added hourly. When medium was not changed, release rates fell off rapidly, probably due to re-uptake of released free fatty acid. Chloroquine did not affect the rate of free fatty acid release. The results suggest that macrophages-foam cells can reduce their triglyceride stores via the action of a nonlysosomal (presumably cytoplasmic) neutral triglyceride lipase.