Analysis of autofluorescence pattern in birdshot chorioretinopathy.

PURPOSE: To characterize and correlate the different patterns of fundus autofluorescence (FAF) in patients with birdshot chorioretinopathy (BSCR), with functional and anatomical parameters. METHODS: Twenty-one BSCR patients were prospectively studied in 2013 and 2014. Each patient underwent visual acuity (VA) and visual field (SITA standard 30.2) testing as well as fluorescein and indocyanine green angiography, spectral-domain optical coherence tomography (SD-OCT) B scan, enhanced depth imaging (EDI), and fundus autofluorescence (FAF) imaging. The disease was classified as active, chronic, or quiescent. RESULTS: The patients' mean age was 60.3 ± 9.2 years and 60% were female. Disease duration was 5.7 ± 3.7 years. Autofluorescence imaging showed punctiform hyper-FAF spots in 23 out of the 29 eyes (79%), which was significantly associated with a greater visual field mean deviation (-7 ± 7 versus -3 ± 2 dB, p = 0.04). Hypo-FAF was defined as peripapillary (n = 25; 86.2%), macular (n = 10; 34.5%), lichenoid (n = 17; 58.6%), and/or diffuse (n = 13; 44.8%). Lichenoid hypo-FAF was significantly associated with worse VA (0.18 ± 0.24 vs. 0.05 ± 0.07 LogMAR, p = 0.04). Macular hypo-FAF was associated with a history of macular edema (62.5%; p = 0.06). Diffuse hypo-FAF was observed more frequently (p = 0.01) in chronic disease (66.7%) than in active (0%) or quiescent disease (27.3%). CONCLUSIONS: Autofluorescence analysis in BRSC patients contributes to evaluating disease activity and could be useful to guide follow-up and treatment.

Drain or No Drain Following Pancreaticoduodenectomy: The Unsolved Dilemma.

BACKGROUND AND AIMS: There is no consensus regarding the routine placement of intra-abdominal drains after pancreaticoduodenectomy. We aim to determine the effects of intraperitoneal drain placement during pancreaticoduodenectomy on 30-day postoperative morbidity and mortality. METHODS: Patients who underwent pancreaticoduodenectomy for pancreatic tumors were identified from the 2014-2015 American College of Surgeons-National Surgical Quality Improvement Program Database. Univariate and multivariate analyses adjusting for known prognostic variables were performed. A subgroup analysis was performed based on the risk for development of postoperative pancreatic leak determined by the pancreatic duct caliber, parenchymal texture, and body mass index. RESULTS: A total of 6858 patients with pancreatic tumors who underwent pancreaticoduodenectomy were identified in the 2014-2015 American College of Surgeons-National Surgical Quality Improvement Program Database dataset. In all, 87.4% of patients had intraperitoneal drains placed. A 30-day mortality rate was higher in the no-drain group (2.9% vs. 1.7%, P = 0.003). Patients in the drain group had a higher incidence of overall morbidity (49.5% vs. 41.2%, P = 0.0008), delayed gastric emptying (18.1% vs. 13.7%, P = 0.004), pancreatic fistulae (19.4% vs. 9.9%, P ⩽ 0.0001), and prolonged length of hospital stay over 10 days (43.7% vs. 34.9%, P < 0.0001). Subgroup analysis based on risk categories revealed a higher 30-day mortality rate in the no-drain group among patients with high-risk features (3.1% vs. 1.6%, P = 0.02). Delayed gastric emptying and pancreatic fistula development remained significantly higher in the drain group only in the high-risk category. Prolonged length of hospital stay and composite morbidity remained higher in the drain group regardless of the risk category. CONCLUSION: To our knowledge, this is the largest study to date that aims at clarifying the pros and cons of the intraperitoneal drain placement during pancreaticoduodenectomy for pancreatic tumors. We showed a higher 30-day mortality rate if drain insertion was omitted during pancreaticoduodenectomy in patients with softer pancreatic textures, smaller pancreatic duct caliber, and body mass index over 25. Postoperative 30-day morbidity rate was higher if a drain was inserted regardless of the risk category. Further randomized controlled trials with prospective evaluation of stratification factors for fistula risk are needed to establish a clear recommendation.

BPA exposure is associated with non-monotonic alteration in ESR1 promoter methylation in peripheral blood of men and shorter relative telomere length in peripheral blood of women.

The aim of this study was to evaluate the potential association of urinary Bisphenol A (BPA) levels with estrogen receptor alpha (ESR1) promoter % methylation and relative telomere length in a sample of 482 participants. Urinary BPA concentration was measured using organic phase extraction followed by high performance liquid chromatography mass spectroscopy. Peripheral blood ESR1 promoter % methylation and relative telomere length were measured using direct bisulfite sequencing and real-time polymerase chain reaction, respectively. The mean ± SD urinary BPA concentration adjusted for urinary creatinine was 2.90 ± 4.81 (µg/g creatinine) with a median of 1.86 µg/g creatinine (min-max:

Surgical outcomes among inflammatory bowel disease patients undergoing colectomy : results from a national database.

INTRODUCTION: Colectomy is relatively common in inflammatory bowel diseases (IBD), occurring more in Ulcerative Colitis (UC) as compared to Crohn's disease (CD). The surgical outcomes among this mixed population of patients are not well understood. This study aims to determine the predictors of post colectomy surgical outcomes in this patient population. METHODS: Using the National Surgical Quality Improvement Project (NSQIP) demographics, preoperative and post-operative data were analyzed for all patients undergoing colectomy for either CD or UC. Multiple variables were linked to several outcomes including mortality, anastomotic leak, and reoperation post colectomy. RESULTS: A total of 5049 IBD patients that underwent colectomy were identified. Rate of reoperation and anastomotic leak were significantly increased with steroid intake with an Odds Ratio (OR) of 1.66 (95% Confidence Interval (CI) (1.26-2.19)) and 1.81 (95%CI (1.34-2.45)) respectively. As for 30-day mortality, it was significantly lower among patients on steroid (OR=0.41; 95%CI (0.19-0.86)). Comparing UC to CD, anastomotic leaks were less common among UC patients (OR=0.53; 95%CI (0.37-0.76)), but 30-day mortality was significantly more prevalent among UC patients (OR=8.11; 95%CI (4.22-15.6)). CONCLUSION: Among IBD patients undergoing colectomy, major surgical complications except 30-day mortality appear to increase with the use of preoperative steroids.

Short- and long-term evolution of unstented nonocclusive coronary dissection after coronary angioplasty.

OBJECTIVES: We assessed the short- and long-term clinical and angiographic outcome of nonocclusive unstented dissection after percutaneous transluminal coronary angioplasty (PTCA) and its correlation with restenosis. BACKGROUND: The use of stents has dramatically increased both the number and the cost of coronary revascularization procedures. However, this technique is not completely risk free, and its benefits have not been fully demonstrated in uncomplicated dissections. METHODS: We studied 129 consecutive patients with 49 nonocclusive dissections after PTCA (grades A to D of National Heart, Lung, and Blood Institute classification) and good distal flow (TIMI [Thrombolysis in Myocardial Infarction] flow grade 3). All patients underwent coronary angiography at 24 h and at six months post-PTCA. Clinical status was assessed every three months in the outpatient clinic. Study subjects were matched with 60 other patients in whom stenting was performed for the presence of dissection. RESULTS: In the former group, all but two patients (with type E dissection, which evolved to coronary occlusion and myocardial infarction) improved their dissection score during follow-up: at six months only 18 dissections were still angiographically visible, and no clinical adverse events were recorded. In the dissected vessels, the restenosis rate was significantly lower than in those without dissection (12% vs. 44%, p < 0.001); in the stented vessels, the restenosis rate was 25% (15/60). CONCLUSIONS: In the presence of TIMI flow grade 3, coronary dissection is associated with a favorable outcome and predicts a low restenosis rate. These results caution against the indiscriminate use of intravascular prostheses in the event of nonocclusive coronary dissection.

Characterization of the relative thrombogenicity of atherosclerotic plaque components: implications for consequences of plaque rupture.

OBJECTIVES: The purpose of this study was to determine whether different components of human atherosclerotic plaques exposed to flowing blood resulted in different degrees of thrombus formation. BACKGROUND: It is likely that the nature of the substrate exposed after spontaneous or angioplasty-induced plaque rupture is one factor determining whether an unstable plaque proceeds rapidly to an occlusive thrombus or persists as a nonocclusive mural thrombus. Although observational data show that plaque rupture is a potent stimulus for thrombosis, and exposed collagen is suggested to have a predominant role in thrombosis, the relative thrombogenicity of different components of human atherosclerotic plaques is not well established. METHODS: We investigated thrombus formation on foam cell-rich matrix (obtained from fatty streaks), collagen-rich matrix (from sclerotic plaques), collagen-poor matrix without cholesterol crystals (from fibrolipid plaques), atheromatous core with abundant cholesterol crystals (from atheromatous plaques) and segments of normal intima derived from human aortas at necropsy. Specimens were mounted in a tubular chamber placed within an ex vivo extracorporeal perfusion system and exposed to heparinized porcine blood (mean [+/- SEM] activated partial thromboplastin time ratio 1.5 +/- 0.04) for 5 min under high shear rate conditions (1,690 s-1). Thrombus was quantitated by measurement of indium-labeled platelets and morphometric analysis. Under similar conditions, substrates were perfused with heparinized human blood (2 IU/ml) in an in vitro system, and thrombus formation was similarly evaluated. RESULTS: Thrombus formation on atheromatous core was up to sixfold greater than that on other substrates, including collagen-rich matrix (p = 0.0001) in both heterologous and homologous systems. Although the atheromatous core had a more irregular exposed surface and thrombus formation tended to increase with increasing roughness, the atheromatous core remained the most thrombogenic substrate when the substrates were normalized by the degree of irregularity as defined by the roughness index (p = 0.002). CONCLUSIONS: The atheromatous core is the most thrombogenic component of human atherosclerotic plaques. Therefore, plaques with a large atheromatous core content are at high risk of leading to acute coronary syndromes after spontaneous or mechanically induced rupture because of the increased thrombogenicity of their content.

Exercise-induced ischemic arrhythmias in patients with previous myocardial infarction: role of perfusion and tissue viability.

OBJECTIVES: This study sought to investigate whether residual viability of infarcted myocardium may play a role in the pathogenesis of exercise-induced ventricular arrhythmias. BACKGROUND: We previously showed that transient ischemia within partially infarcted areas often precipitates ventricular arrhythmias during exercise that are consistently obliterated by intravenous nitrates. METHODS: We studied 60 patients with chronic stable angina and a previous myocardial infarction. All underwent at least two consecutive exercise stress tests, coronary angiography and stress/rest myocardial perfusion tomography by Tc-99m 2-methoxy isobutyl isonitrile (MIBI). In the last 26 consecutive patients, residual viability was assessed by single-photon emission computed tomography (SPECT) using fluorine (F)-18 fluorodeoxyglucose. Perfusion and metabolic data were evaluated qualitatively by three independent observers in blinded manner. RESULTS: With exercise, 30 patients (group A) consistently developed ventricular arrhythmias (> 10 ventricular ectopic beats/min, couplets, nonsustained ventricular tachycardia); the remaining 30 patients (group B) did not. The severity of coronary artery disease (Gensini score) was similar in the two groups. Postexercise SPECT showed partial reperfusion of an infarcted area in 28 of 30 patients of group A but in only 9 of 30 of group B (p < 0.0001). Uptake of F-18 fluorodeoxyglucose was observed within the infarcted zone in 10 of 13 and 1 of 13 patients in groups A and B, respectively (p = 0.0003). CONCLUSIONS: In patients with myocardial infarction, exercise-induced ventricular arrhythmias appear to be triggered by transient ischemia occurring within a partially necrotic area containing large amounts of viable myocardium. Therefore, occurrence of arrhythmias during exercise may represent a clue to the presence of residual viability within a previously infarcted area.

Different response to balloon angioplasty of carotid and coronary arteries: effects on acute platelet deposition and intimal thickening.

PTCA is a well-established intervention to reduce the severity of atherosclerotic coronary stenosis. Its primary success rate is seriously handicapped by the high incidence of late restenosis. Given the clinical and social importance of this proliferative process, new strategies are needed to prevent or reduce restenosis. Several animal models as well as different arteries have been used to study neointimal proliferation after arterial injury. A number of agents have shown to reduce neointimal proliferation after arterial injury in the carotids and iliac arteries of rodent models. Unfortunately, these results have not been replicated in humans. We have compared the acute and late response to vascular injury of the carotid and coronary arteries in the pig. Arterial injury was induced by performing balloon angioplasty of the carotid (elastic) and coronary (muscular) arteries in swine. Acute platelet-thrombus formation was evaluated by quantitation of Indium-labeled platelets deposited on the injured segments 1 h after procedure. Measurement of intimal area was performed by morphometry of the most stenotic cross-section at 28 days after balloon angioplasty. Platelet deposition after mild and severe injury in carotids (4 +/- 1 and 56 +/- 13 x 10(6) platelets/cm2, respectively) and coronaries (15 +/- 5 and 141 +/- 20 x 10(6) platelets/cm2, respectively) are significantly greater in deep, than in mild injury (P < 0.005), and significantly greater in coronary than in carotid arteries after deep injury (P < 0.05). Likewise, late neointima formation was significantly greater (P < 0.05) after mild and severe injury in coronary (17 +/- 0.5 and 56 +/- 2%, respectively) than in carotid arteries (5 +/- 0.5 and 12 +/- 1%, respectively). Acute platelet-thrombus formation and late neointimal thickening are modulated by the degree of injury induced during the interventions; and after disruption of the internal elastic lamina, coronary arteries always had significantly more acute thrombus and neointimal thickening. This study emphasizes the importance of the animal species, the type of injury and the artery chosen for studies on restenosis post interventions.

Muramidase: A useful monocyte/macrophage immunocytochemical marker in swine, of special interest in experimental cardiovascular disease.

The reliability of a rabbit polyclonal antibody against muramidase to identify monocytes/macrophages in swine was evaluated by immunostaining of cell smears and formaldehyde-fixed, paraffin-embedded tissue sections. Blood in tissue sections, cell smears (peripheral blood, buffy coat, and isolated mononuclear cells), and cultured mononuclear cells (adherent monocytes) contained positively stained cells with a morphology and in a number corresponding to that expected for a monocyte marker. Polymorphonuclear leukocytes (PMN), lymphocytes, and platelets were negative. In normal organs and tissues, mesenchymal cells with a distribution similar to that expected for macrophages were found to stain positively for muramidase. In pathologic tissues, positively stained inflammatory cells were identified in wounds, infected lungs, recently infarcted myocardium, and acute (variable numbers), organizing (often many), and healed (usually few) arterial thrombi. Enzymatic unmasking of antigenic determinants by trypsinization was necessary to achieve strong and consistent staining of monocytes/macrophages in tissue sections. A variety of epithelial cells of no differential diagnostic significance for monocyte/macrophage identification (e.g., renal proximal tubular cells) also stained positive for muramidase. The staining pattern of muramidase in swine corresponds to that described in humans, in whom muramidase has been shown to be a valuable marker of monocytes/macrophages. Swine PMN were, however, not stained or only weakly stained, whereas human PMN reportedly are strongly positive. As in humans, swine cardiac myocytes, smooth muscle cells, endothelial cells, lymphocytes, and platelets were consistently negative. This antibody against muramidase is a useful immunohistochemical marker for swine monocytes/macrophages in formaldehyde-fixed, paraffin-embedded tissues.

Protein S and protein C anticoagulant activity in acute and chronic cardiac ischemic syndromes. Relationship to inflammation, complement activation and in vivo thrombin activity.

Protein S (PS) and protein C (PC) anticoagulant activities and thrombin-antithrombin complex (TAT) were measured in 20 patients with AIS, 25 patients with chronic stable angina (CSA) and a control group (C). Although plasma levels of TAT were significantly elevated in patients with CSA (p < 0.01 vs C), they were much higher in patients with AIS (p < 0.001 vs CSA). PC anticoagulant activity was similar in patients and controls. At variance, PS anticoagulant activity was lower in patients with AIS than in those with CSA and controls (p < 0.05), reflecting differences in total PS and C4B-binding protein (C4B-BP) antigen possibly resulting from involvement in the mechanisms of inflammation, complement activation and acute-phase response. The ratios of anticoagulant PS and PC to procoagulant vitamin K-dependent factors IX and II were reduced in AIS patients (0.05 > p > 0.005 vs C). In addition, the ratios of anticoagulant PC and PS to factor IX were lower in patients with AIS than in those with CSA (p < 0.05). These results indicate that in patients with acute ischemic cardiac syndromes the markedly increased in vivo thrombin generation is associated with an unbalance between coagulant and anticoagulant vitamin K-dependent factors.

Beneficial effects of diltiazem during myocardial reperfusion: a randomized trial in acute myocardial infarction.

BACKGROUND: Although in experimental models of coronary occlusion diltiazem administration has been shown to reduce the degree of stunning and of reperfusion injury, the majority of clinical trials has failed to demonstrate significant benefits. The aim of this study was to evaluate the effect of diltiazem, administered before coronary reperfusion, on infarct size, residual myocardial viability and recovery of left ventricular function. METHODS: We studied 90 patients admitted within 3 hours of the onset of symptoms of acute myocardial infarction. They were immediately randomized to either intravenous diltiazem (10 mg bolus + 10 mg/hour for 3 days) (group 1, n = 43) or placebo (group 2, n = 47) and subsequently treated with recombinant tissue-type plasminogen activator. All underwent serial echocardiograms upon admission, 4 days post-admission during low-dose dobutamine stress echo, at discharge and after 6 months. We calculated the dysfunction score (1 = hypokinesia, 2 = akinesia, 3 = dyskinesia) on admission and its percent reduction after dobutamine (viability) and at follow-up (recovery). The 12-lead electrocardiograms were continuously monitored for 3 days and coronary angioplasty was performed whenever the residual stenosis was > 60%. RESULTS: Upon admission, there were no differences in age, sex, infarct location and size, degree of ST-segment elevation, time from onset of symptoms and dysfunction score. Creatine kinase peaked early in 70% of patients in both groups; the incidences of recurrent ischemia, infarct-related vessel patency and the need for coronary angioplasty were also similar. The creatine kinase peak was significantly higher in group 2 (2931 +/- 2456 vs 1726 +/- 1004 IU/l, p < 0.05). Conversely, in group 1 the residual viability was significantly higher (51 +/- 23 vs 36 +/- 30% improvement in dysfunction score, p < 0.05) and the early recovery of regional function was significantly greater (35 +/- 34 vs 18 +/- 22% at discharge, p < 0.05). On the other hand, the delayed recovery was not significantly different (15 +/- 29 vs 21 +/- 32% from the time of discharge to 6 months of follow-up). CONCLUSIONS: Intravenous diltiazem, started before coronary reperfusion, has beneficial effects on the infarct size, residual viability and recovery of regional function. If confirmed by larger trials, these preliminary results suggest the use of diltiazem as adjunctive therapy in patients with acute myocardial infarction and undergoing reperfusion.

Intravenous nitroglycerin suppresses exercise-induced arrhythmias in patients with ischaemic heart disease: implications for long-term treatment.

We studied 20 patients with ischaemic heart disease, who consistently developed complex ventricular arrhythmias during exercise testing. Treadmill exercise was performed twice, both during the placebo infusion and then during intravenous administration of nitroglycerin, titrated to reduce systolic blood pressure by 10 mmHg. Exercise duration in those administered placebo was 7.8 +/- 1.7 and 7.9 +/- 1.5 min, respectively (ns); angina developed in five patients and ischaemic ST changes in 10. In those administered nitroglycerin, exercise duration increased to 8.4 +/- 2 min (P less than 0.05). Diagnostic ST segment depression was observed in only two patients and only one had angina. Ventricular arrhythmias, consistently present during both tests on those administered placebo, were dramatically reduced by nitroglycerin in all 20 patients. There were 455 (mean 35.8 +/- 16.8) and 418 (mean 34.4 +/- 11.1) ventricular ectopic beats in the two exercise tests on those administered placebo and 11 in those receiving the nitroglycerin infusion (mean 0.6 +/- 0.1) (P less than 0.001). There were 28 and 29 couplets in those receiving placebo (ns) and none in those receiving nitroglycerin (P less than 0.001). Ventricular tachycardia was present in six and eight patients who received placebo but in none in those administered nitroglycerin (P less than 0.001). Abolition of exercise-induced arrhythmias was maintained during chronic treatment with oral coronary vasodilators. Prevention of exercise-related arrhythmias by nitroglycerin appears a good indicator of their ischaemic origin and may provide valuable information for long-term prophylaxis with oral vasodilators, thus avoiding antiarrhythmic agents with their potential side effects.

[The coronary collaterals influence in the recovery phase after exercise-induced myocardial ischemia]. / I collaterali influenzano la fase di recupero dopo ischemia miocardica indotta da esercizio.

The role of coronary collaterals in conditioning the recovery from exercise-induced myocardial ischaemia has not been investigated. We studied 60 patients (54 men, age 59.3 +/- 6.7 years) with low threshold effort angina and documented coronary artery disease, who underwent repeat exercise testing in 2 consecutive days. On the second day, Thallium 201 stress/rest myocardial perfusion scintigraphy was also performed. At angiography, 30 patients (Group A), had more severe disease (Gensini score: 46.9 +/- 16) and angiographically visible collaterals (grade 2-3 Cohen and Rentrop classification) perfusing the ischaemic zone; the other 30 (Group B), had lesser disease (Gensini score: 28.6 +/- 18, p less than 0.001 vs Group A) and non visible collaterals to the ischaemic areas. Maximal ST depression and total exercise duration were similar in the 2 groups (2.5 +/- 0.6 vs 2.5 +/- 0.7 mV and 6.2 +/- 1.8 vs 6.8 +/- 1.9 min, respectively) but time and rate-pressure product to 1 mm ST depression were lesser in Group A (3.5 +/- 0.8 vs 4.8 +/- 0.6 min, p less than 0.01, and 14189 +/- 2451 vs 16081 +/- 2215 b/min x mmHg, p less than 0.04). Surprisingly, in Group A, the ST segment returned to the baseline more rapidly (5.5 +/- 1.6 vs 11.7 +/- 3.3 min, p less than 0.001), and the ischaemic area [time (s) x ST (mV)], measured in the recovery period, was also smaller (301 +/- 163 vs 621 +/- 260, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

[Intravenous nitroglycerin infusion suppresses exercise-induced arrhythmia in patients with ischemic cardiopathy: indications for chronic treatment ]. / L'infusione endovenosa di nitroglicerina sopprime le aritmie indotte da slorzo in pazienti con cardiopatia ischemica: indicazioni per il trattamento cronico.

In patients with ischemic heart disease and arrhythmias, selection of antiarrhythmic treatment is often difficult as it is hard to separate "primary" from ischemic arrhythmias. We studied 20 patients with ischemic heart disease, who developed ventricular arrhythmias consistently during exercise test. Exercise test was performed twice during infusion of placebo and then during intravenous administration of nitroglycerin, titrated to reduce systolic blood pressure by 10 mmHg. Exercise duration was 7.8 +/- 1.7 and 7.9 +/- 1.5 min, in the 2 placebo tests (NS). Angina developed in 5 patients and ischemic ST changes in 10. With nitroglycerin exercise duration increased to 8.4 +/- 20 min (p less than 0.05), diagnostic ST segment depression was observed in 2 patients and only 1 had angina. In all 20 patients, ventricular arrhythmias were consistently present during both tests on placebo, that were markedly reduced by nitroglycerin. In fact, ventricular ectopic beats were 455 (mean 35.8 +/- 16.8) and 418 (mean 34.4 +/- 11.1) in the 2 exercise tests with placebo, and 11 during nitroglycerin infusion (mean 0.6 +/- 0.1; p less than 0.001). Couplets were 28 and 29 during placebo (NS) and 0 during nitroglycerin (p less than 0.001). Ventricular tachycardia was present in 6 and 8 patients during placebo but in none during nitroglycerin (p less than 0.001). Reduction of exercise-induced arrhythmias was maintained during chronic treatment with oral vasodilators. Prevention of exercise-related arrhythmias by nitroglycerin infusion appears a good indicator of their ischemic origin and may provide valuable information for long-term profilaxis with oral vasodilators, then avoiding the use of antiarrhythmic agents and their potential side effects.

Inhibition of growth of thrombus on fresh mural thrombus. Targeting optimal therapy.

BACKGROUND: Residual mural thrombus on severely damaged arterial wall is very thrombogenic. We tested the hypothesis that direct thrombin inhibition will block thrombus growth on fresh thrombus better than indirect thrombin inhibition, cyclooxygenase inhibition, or both. METHODS AND RESULTS: A fresh mural thrombus was formed by directly perfusing fresh porcine blood for 5 minutes over severely damaged arterial wall at a high shear rate in a well-characterized ex vivo perfusion system. The average platelet (P) and fibrinogen (F) deposition (D) achieved in 5 minutes were 382 +/- 32 x 10(6) platelets/cm2 and 296 +/- 36 x 10(12) fibrinogen molecules/cm2, respectively. Thrombus growth on the fresh mural thrombus was quantitated by directly perfusing blood from pigs with 111In-labeled platelets and 125I-labeled fibrinogen for an additional 5 minutes over the preformed mural thrombus. Treatment included recombinant hirudin (1 mg/kg per hour IV) as a probe for thrombin, aspirin (5 mg/kg IV) as a platelet inhibitor of cyclooxygenase, heparin (moderate, 100 IU/kg per hour IV; high-dose, 250 IU/kg per hour IV) as an indirect thrombin inhibitor, and heparin (100 IU/kg per hour) plus aspirin (5 mg/kg IV). Thrombus growth as measured by labeled PD (x 10(6)/cm2) and FD (x 10(12) molecules/cm2) was mildly but not significantly reduced by aspirin (1034 +/- 92 and 436 +/- 78, respectively) compared with baseline (1113 +/- 67 and 545 +/- 52, respectively). Inhibition of thrombus growth with heparin was dose dependent. A regression analysis showed an inverse correlation of PD and FD with mean plasma heparin concentrations (r = -.81, P = .0001 and r = -.49, P = .0007, respectively). Recombinant hirudin led to a profound inhibition of thrombus growth (PD, 30 +/- 12; FD, 109 +/- 21), which was significant compared with all groups, even the highest dosage of heparin (250 IU/kg per hour). CONCLUSIONS: Specific thrombin inhibition markedly inhibits platelet and fibrinogen deposition onto fresh mural thrombus at a high shear rate. Aspirin alone or in combination with heparin has little effect on evolving thrombosis. Heparin dose dependently reduces thrombus growth, but even the highest dosage is less effective than hirudin. Thrombin appears to be the primary activator of platelets by fresh thrombus.

Coronary collaterals reduce the duration of exercise-induced ischemia by allowing a faster recovery.

The role of collaterals in influencing postischemic recovery after exercise testing has not been investigated previously. We studied 54 patients (mean age 59 +/- 6 years) with effort-induced angina and documented coronary disease who underwent exercise testing and thallium-201 myocardial scintigraphy. On angiography, 30 patients (group A) exhibited visible collaterals (grade 2 to 3, Cohen and Rentrop classification) perfusing the ischemic zone, whereas the other 24 (group B) did not. Patients with collaterals had more severe coronary artery disease (Gensini score 46.9 +/- 16 vs 28.6 +/- 18; p less than 0.001) and more severe impairment of coronary flow reserve (time and rate-pressure product to 1 mm ST segment depression 3.5 +/- 0.8 vs 4.8 +/- 0.6 minutes, p less than 0.01; 14,189 +/- 2451 vs 16,081 +/- 2215 beats/min x mm Hg, p less than 0.04, respectively). However, in these patients the ECG returned to baseline more rapidly after exercise (5.5 +/- 1.6 vs 11.7 +/- 3.3 minutes; p less than 0.001). Therefore, although collaterals do not apparently prevent or delay the development of exercise-induced ischemia, they can limit its duration by allowing a faster recovery.

Effect of an eccentric severe stenosis on fibrin(ogen) deposition on severely damaged vessel wall in arterial thrombosis. Relative contribution of fibrin(ogen) and platelets.

BACKGROUND: Coronary thrombosis is a dynamic process dependent on the pathological substrate, the local shear forces, and blood factors. METHODS AND RESULTS: We investigated the effect of a severe (80%) eccentric stenosis on fibrin(ogen) interaction with a deeply damaged vessel wall, its relation to platelet deposition in thrombus formation, and the influence of time on thrombus growth. Porcine 125I-fibrinogen and autologous 111In-platelets were injected into pigs instrumented for extracorporeal circulation and treated with low-dose heparin (aPTT ratio < 1.5) that has been previously shown and herein confirmed not to affect platelet and/or fibrin(ogen) attachment. Tunica media, as a model of severely injured vessel wall, was mounted in a tubular perfusion chamber containing an eccentric axisymmetric sinusoidal stenosis obstructing the lumen and exposed for 1, 5, and 10 minutes to perfusing blood. A shear rate of 424 s-1 at the laminar, parallel parabolic local flow perfused segments one to two orders of magnitude greater at the apex of the stenosis. Fibrin(ogen) deposition, its axial distribution with respect to the apex, and its relation to platelet deposition were determined by an ex vivo analysis of the test substrates. Fibrin(ogen) and platelet deposition were both significantly higher at the apex of the stenosis than at either the prestenotic or poststenotic area at all the studied perfusion times (P < .02). However, fibrin(ogen) deposition demonstrated a significantly smaller degree of increase from the prestenotic area to the apex as well as a smaller degree of decrease from the latter to the poststenotic region, compared with platelet deposition (P < .05). Although both fibrin(ogen) and platelet deposition increased over time, the ratio of fibrin(ogen) to platelets showed a progressive decrease that became significant from 5 to 10 minutes (P < .03) at either low or high shear rate. The rate of platelet deposition was relatively constant; however, fibrin(ogen) deposition progressively decreased, especially at the apex. CONCLUSIONS: On severely damaged vessel wall, fibrin(ogen) and platelet deposition is maximal at the apex of the stenosis where shear rate is extremely high and parallel streamlines are deformed. Nevertheless, fibrin(ogen) deposition is significantly less dependent on high shear rate than is platelet deposition, and the pattern is not influenced by time. Finally, fibrin(ogen) deposition appears to be predominant in the thrombus layers adjacent to a severely damaged vessel wall regardless of the local shear stress levels and flow conditions.

Local delivery of r-hirudin by a double-balloon perfusion catheter prevents mural thrombosis and minimizes platelet deposition after angioplasty.

BACKGROUND: The major morbidity of percutaneous transluminal coronary angioplasty is acute thrombosis and restenosis of the dilated lesion. Platelet-thrombus deposition occurs within minutes after injury, is primarily mediated by thrombin, causes acute occlusion, and contributes to late restenosis. Experimentally, specific thrombin inhibitors have prevented mural thrombosis. However, local therapy may be more effective than systemic treatment. We tested the hypothesis that high local concentrations of an antithrombin drug at the site of arterial injury following balloon angioplasty inhibit platelet thrombus formation equally or better than conventional systemic treatment and at lower systemic anticoagulant levels. METHODS AND RESULTS: Balloon angioplasty of the carotid arteries of 29 pigs was performed using systemic intravenous treatment with heparin (100 U/kg, groups I and II), suboptimal r-hirudin (0.3 mg/kg, group III), and higher-dose r-hirudin (0.7 mg/kg, group IV), which is the lowest dose that completely inhibited arterial thrombosis in the pig. Immediately after balloon angioplasty of the first carotid, additional local therapy with placebo (group I) or r-hirudin (groups II, III, and IV; 0.3 mg/kg in 1 mL) was administered with distal perfusion through a new percutaneous double-balloon catheter. After 1 hour of local drug delivery, angioplasty of the contralateral carotid was performed. Reflow for 1 hour was permitted to both carotids to compare the short-term effect of local plus systemic treatment with systemic treatment on quantitative 111In-labeled platelet deposition and macroscopic mural thrombus formation on deeply injured carotid segments. Local drug delivery of placebo compared with systemic heparin treatment resulted in no change of platelet deposition (x 10(6)/cm2, mean +/- SEM) in controls (group I, 91.0 +/- 23.5 versus 80.8 +/- 19.4), but local delivery of r-hirudin resulted in a significant reduction in group II (15 +/- 2.5 versus 71.3 +/- 14.5; P < .02) and group III (11.4 +/- 2.5 versus 80.5 +/- 11.4; P < .01) and was borderline in group IV (7.4 +/- 1.8 versus 14.1 +/- 7.4; P = .05), respectively. The incidence of macroscopic mural thrombus formation with local and systemic treatment was 86% and 75% in group I, 16% and 70% in group II, 14% and 71% in group III, and 0% and 16% in group IV, respectively. CONCLUSIONS: Local therapy with the specific thrombin inhibitor r-hirudin significantly reduces short-term quantitative platelet deposition and macroscopic mural thrombus formation following balloon angioplasty compared with systemic treatment of conventional doses of heparin and hirudin and requires a significantly smaller amount of the recombinant drug.

A new approach for local intravascular drug delivery. Iontophoretic balloon.

BACKGROUND: Catheter-based systems are being developed to deliver drugs directly into the vessel wall. Pressure-mediated trauma and lack of homogeneous delivery are key limitations of these approaches. METHODS AND RESULTS: We studied a new catheter-based delivery system that uses electrical current to force the drug into the vessel wall. The in vivo feasibility of this approach has been assessed by delivering 125I-hirudin into porcine carotid arteries. Vascular levels of hirudin after active iontophoresis (4 mA/cm2, 5 minutes) were 80-fold greater than those achieved by passive diffusion (without electricity). Tissue hirudin levels declined over time; by 1 hour after delivery, 80% of the drug had left the vessel wall, and by 3 hours later, the levels of hirudin within the wall were similar to those achieved by passive diffusion. Autoradiography revealed distribution of the drug throughout the entire circumference of the arterial wall within the intima, media, and adventitia. Iontophoresis-mediated vessel wall trauma was minimal (less than 10% endothelial denudation and medial smooth muscle cell damage). Balloon injury after local delivery changed neither kinetics nor distribution of the drug into the arterial wall. CONCLUSIONS: (1) High local concentrations of hirudin in the arterial wall may be achieved with the iontophoretic balloon catheter. (2) The drug is distributed throughout the entire vessel wall without significant damage. (3) The retention of hirudin in the arterial wall is time dependent. (4) This technique might be useful to deliver therapeutic agents before or after percutaneous vascular interventions.

Human monocyte-derived macrophages induce collagen breakdown in fibrous caps of atherosclerotic plaques. Potential role of matrix-degrading metalloproteinases and implications for plaque rupture.

BACKGROUND: Rupture of the fibrous cap of the atherosclerotic plaque is a key event that predisposes to coronary thrombosis, leading to acute coronary syndromes. Recent studies have shown that the fibrous caps of vulnerable and ruptured atherosclerotic plaques have reduced collagen and glycosaminoglycan content in association with an increased macrophage density and a reduced smooth muscle cell density. Since collagen breakdown in the fibrous caps may contribute to a thinning and weakening of the cap, increasing its vulnerability to rupture, we tested the hypothesis that monocyte-derived macrophages, by producing matrix-degrading metalloproteinases (MMPs), could induce collagen breakdown in human atherosclerotic fibrous caps. METHODS AND RESULTS: Monocytes were isolated from human blood by Ficoll-Paque density gradient and allowed to grow in cell culture until phenotypic and staining characteristics indicated transformation into macrophages (4 to 7 days). Fibrous caps were dissected from human aortic or carotid plaques and incubated for 48 hours with macrophages in serum-free medium without (n = 21) and with (n = 10) an MMP inhibitor or with cell- and serum-free medium only (n = 9). Hydroxyproline released in the culture medium was measured by a spectrophotometric method and used as evidence of collagen breakdown in the fibrous caps. Immunocytochemistry with specific monoclonal antibodies was used to identify expression of MMP-1 (interstitial collagenase) and MMP-2 (72-kD gelatinase) in cell culture, and zymography was used to detect MMP activity in the culture supernatant. The amount of hydroxyproline released was significantly greater when fibrous caps were incubated with macrophages than when incubated with cell-free medium (0.4 +/- 0.16 micrograms.mL-1.mg-1 versus 0.02 +/- 0.03 micrograms.mL-1.mg-1 of tissue; P < .04 by Mann-Whitney test). There was no hydroxyproline release when fibrous caps were incubated with macrophages in the presence of an MMP inhibitor. Immunocytochemistry demonstrated MMP-1 and MMP-2 expression by macrophages between days 4 and 7, and zymography confirmed the presence of MMP-2 activity in the supernatant. CONCLUSIONS: In this study, human monocyte-derived macrophages were shown to induce collagen breakdown in fibrous caps of human atherosclerotic plaques associated with cellular expression and zymographic evidence of MMP activity; no evidence of collagen breakdown was found in the presence of an MMP inhibitor. These findings support the hypothesis that increased macrophage density and/or activation in the atherosclerotic plaque may induce collagen breakdown in the fibrous cap by secreting MMPs and possibly other proteases, thus contributing to vulnerability to plaque rupture.