From the Division of Cardiology (B.J.M.), Department of Medicine,
University Hospital Inselspital, Bern, Switzerland; The Mount Sinai Medical
Center (J.J.B., J.H.C., J.T.F., V.F.), New York, NY; and Cardiovascular
Research Center (L.B.), CSIC-H Sant Pau, Barcelona, Spain.
Correspondence to Beat J. Meyer, MD, Division of Cardiology, Department of Medicine, University Hospital Inselspital, 3010 Bern, Switzerland. E-mail bmeyer{at}insel.unibe.ch
Methods and Results—A fresh mural thrombus was formed by
perfusing severely injured arterial wall with porcine blood
for 5 minutes at a shear rate of 1690 s-1. Thrombus
formation was measured by morphometric analysis
(mm2/mm). The average size of a mural thrombus formed in 5
minutes was 0.14±0.03 mm2/mm. Progression of thrombus
growth within 10 minutes triggered by the preformed thrombus was
evaluated in pigs treated with r-hirudin (1 mg/kg per hour IV) as a
probe for thrombin, high-dose heparin (250 IU/kg per hour IV),
moderate-dose heparin (100 IU/kg per hour), moderate-dose heparin (100
IU/kg per hour) plus aspirin, aspirin alone (5 mg/kg IV), and placebo.
Hirudin was associated with a significant decrease (48%) of mural
thrombus area and significantly reduced growth of thrombus
(0.07±0.01), even compared with the highest dose of heparin
(0.15±0.03), although at lower levels of anticoagulation. Inhibition
of growth of thrombus with heparin was dose dependent, showing an
inverse correlation of thrombus area with mean plasma heparin
concentrations (r=.77, P=.0001). Thrombus
size was unchanged by aspirin (0.29±0.07) compared with controls
(0.28±0.07).
Conclusions—Direct inhibition of thrombin activity with r-hirudin
completely inhibits growth of thrombus, causes dissolution of a
preexisting mural thrombus, and is more effective at lower levels of
anticoagulation than the highest dose of heparin at shear rates typical
of a moderate coronary stenosis.
The current approach of combining antiplatelet and antithrombotic
therapy is based on the proposed roles of both activated
platelets and thrombin in growth of arterial thrombus
in acute coronary syndromes. Despite the proven clinical
efficacy of heparin and aspirin in the treatment of acute
coronary syndromes, more effective regimens with acceptable
safety profiles are needed.
Several groups have studied the relationship among surface composition,
shear rate, and platelet thrombus formation, but very few have
studied the effect of an already formed platelet-rich thrombus on
the growth of thrombus under flow condition similar to a moderately
stenosed coronary artery. In a previous study, we used an
extracorporeal perfusion model to study the growth of thrombus
triggered by a fresh mural thrombus.9 Growth rate
was measured using blood containing 111In-labeled
platelets and 125I-labeled fibrinogen. In
this study, we analyzed the perfused aortic segments
histologically and applied morphometric
analysis to quantify the effects of different antithrombotic
treatments on the preformed mural thrombus. We tested the hypothesis
that thrombin activity is necessary for cohesion of platelet-rich
thrombus and that specific thrombin inhibition but not current
antithrombotic therapy is effective in deaggregating fresh
platelet-rich mural thrombus.
The carotid artery and contralateral external jugular vein were
cannulated through a longitudinal left and right neck incision to
establish an extracorporeal circuit as previously
described.12 The carotid artery was directly
connected with polyethylene tubing (20 cm in length; Clay Adams, PE
200, Division of Becton, Dickinson and Co) to the input of the
Plexiglas chamber. The output of the chamber was connected to a
peristaltic pump (Masterflex, model 7013; Cole-Palmer Instrument).
Blood that had passed through the perfusion chamber was recirculated
back into the animal by the contralateral external jugular vein. All
animals received low-dose anticoagulation with heparin (50 IU/kg; mean
activated partial thromboplastin time [aPTT] ratio, 1.4±0.1)
as a continuous infusion to avoid clotting inside the tubing system.
Low-dose heparin does not affect platelet or fibrin(ogen)
deposition compared with native (nonanticoagulated)
blood.13 14
Perfusion Chamber
Evaluation of Thrombus Growth
After the preperfusion period with buffer, blood from the first pig was
passed through the chamber at a flow rate of 10 mL/min for 5 minutes to
create a fresh thrombus on tunica media. Then, the growth of thrombus
on preformed fresh thrombus was measured under the same flow conditions
using blood from the second pig assigned to different antithrombotic
treatment groups. The changes of perfusion from buffer to blood, from
blood of the first pig to blood of the second pig, and from blood to
buffer were achieved manually with three-way stopcocks without the
introduction of stasis or air in the chamber. One stopcock was used to
discard blood and buffer before autologous blood was recirculated
through the jugular vein.
This method of evaluation of growth of thrombus on a preformed thrombus
has been validated previously.9 We have shown
that the rate of platelet deposition on severely damaged wall at
high shear rates is characterized by a first-order rate
constant.16
Experimental Groups
The first group received aspirin at a dose of 5 mg/kg IV
(lysinated acetylsalicylic acid;
Synthelabo-Pharma). This dose of aspirin completely abolished
arachidonic acid–induced platelet aggregation
(0.9 mmol/L final concentration; Sigma Chemical) in whole blood
measured 20 minutes later. The second group was administered heparin as
an intravenous bolus of 100 IU/kg followed by a continuous
infusion of 100 IU/kg per hour during the treatment period (heparin
sodium USP, derived from porcine intestinal mucosa; Elkins-Sinn). The
third group received the same dose of heparin in combination with
intravenous aspirin (5 mg/kg). The fourth group was given
heparin as an intravenous bolus of 250 IU/kg followed by a
continuous infusion of 250 IU/kg per hour. The fifth group received
hirudin (recombinant desulfato hirudin; CGP 39393, Ciba-Geigy) as an
intravenous bolus of 1 mg/kg followed by a continuous
infusion of 1 mg/kg per hour. This hirudin concentration totally
inhibited thrombin induced-platelet aggregation (5 U/mL; Sigma) in
whole blood.
Morphometric Quantification of Thrombus Formation
Laboratory Measurements
Data Analysis
Hirudin was associated with a significant decrease of total thrombus
area compared with baseline mural thrombus formation, indicating
dissolution of preformed mural thrombus (P<.001, Fig 1
Thrombus size in groups treated with heparin 100 IU/kg per hour
alone and the combination of heparin 100 IU/kg per hour and aspirin was
significantly lower compared with controls but was not significantly
different from each other. A greater inhibition of growth of thrombus
in pigs treated with very high doses of heparin (250 IU/kg bolus plus
250 IU/kg per hour infusion) occurred when compared with control
(P<.001) and compared with those treated with lower doses
of heparin (100 IU/kg per hour, P<.01). In fact, thrombus
size correlated strongly and significantly with plasma heparin
concentrations (r=.77, P=.0001, Fig 3
Thrombus size was not changed in pigs treated with aspirin alone
compared with controls.
Hemostatic Parameters
To assess the level of anticoagulation in the different experimental
groups in this study, the aPTT test and heparin levels using
anti–factor Xa activity test were performed from hourly samples taken
over a 6-hour period. Note that baseline and control perfusions of all
experimental groups were carried out at a low level of anticoagulation
(mean aPTT ratio, <1.5 with 50 IU/kg heparin). In the heparin (100 IU)
and heparin (100 IU)-plus-aspirin groups, the aPTT was prolonged to
2.4±0.26 and 2.2±0.03 times baseline control value, respectively. In
the heparin (250 IU) group, the aPTT was prolonged to >12.1 times
baseline control value. In the hirudin group, the aPTT was prolonged to
3.3±0.01.
Specific thrombin inhibition not only completely blocked growth of
thrombus but also significantly decreased thrombus size of preformed
mural thrombus at lower levels of anticoagulation than those achieved
with high-dose heparin. Growth of thrombus induced by preformed, fresh
mural thrombus was lowest in pigs treated with the specific thrombin
inhibitor r-hirudin at a dose that prevented macroscopic
mural thrombus after deep injury13 14 and
increased with decreasing antithrombin activity, confirming our
previous results.9 Thrombus size in animals
treated with aspirin was not significantly reduced at these rheological
conditions, a finding that is consistent with previous
results.9 22
Thrombin plays a central role in the formation, growth,
maintenance, and consolidation of thrombus. Direct thrombin
inhibition with hirudin, but not heparin, blocks these processes and
leads to profound inhibition of thrombus14 23 24 25
and even to dissolution of preformed thrombus, as in our study. In
vivo, in the pig with a carotid artery crush injury, 90% of the
preformed, half-hour-old thrombus dissolved within 1 hour of hirudin
administration.26 The superior antithrombotic
efficacy of specific thrombin inhibition over heparin appears to be due
to several mechanisms, including better inhibition of catalytically
active clot-bound thrombin,27 28 lack of natural
inhibitors against hirudin but present against
heparin,29 30 and high affinity for platelet
thrombin receptor by r-hirudin, which can displace thrombin bound to
platelet receptor.31 Antithrombins with
greater binding affinity to thrombin have greater antiplatelet
potential, as demonstrated by graded reduction in thrombin affinity of
r-hirudin mutants, which resulted in a progressive attenuation of
antiplatelet activity.32
In addition, the significant decrease of thrombus size seen in our
study with specific thrombin inhibition suggests disaggregation of
platelets, facilitated endogenous
fibrinolysis, or both, an observation also made in
recent in vitro and in vivo studies.26 33 34 Most
likely, disaggregation of platelet-rich thrombi is the predominant
mechanism of dissolution of the mural thrombi in the present study.
Although stable thrombin inhibition may enhance endogenous
fibrinolysis, the mechanism by which this effect is
obtained remains unclear. Inhibition of platelet aggregate
formation and thrombin-mediated fibrin formation appears to shift the
dynamic hemostatic balance toward fibrinolysis,
resulting in an overall reduction in thrombus
size.35 Contributing mechanisms for facilitating
endogenous fibrinolysis may be the
inhibition of fibrin cross-linking, which is necessary for stable clot
formation; cross-linking of
In the present study, dissolution of platelet-rich
thrombus occurred at a dose of r-hirudin that completely abolished
platelet thrombus formation in previous
studies.9 14 In the hirudin group, the mean aPTT
ratios were 3.3, which were significantly lower those than in the
high-dose heparin group (>12 times control). In patients receiving
r-hirudin for 3 to 5 days, thrombus dissolution in
aortocoronary vein grafts occurred at aPTT levels that were two
to three times those of control.34 However, if
r-hirudin is administered in combination with
thrombolytic agents (rt-PA), residual platelet-rich
thrombus may be eliminated at lower levels of anticoagulation (aPTT
ratios, 2.5 times control).10 In experimental
studies of coronary thrombosis, hirudin was superior to heparin
in facilitating thrombolysis with both t-PA and
streptokinase10 39 40 and almost completely
eliminated residual platelet-rich thrombus.10
Dissolution of mural thrombus by specific thrombin inhibiton with
r-hirudin is of potential therapeutic benefit after acute
coronary syndromes that could lead to improved vessel patency
with reduced stenosis, thus decreasing the need for
revascularization procedures in a significant
proportion of patients.
In summary, specific thrombin inhibition with r-hirudin blocks
the growth of thrombus and leads to a reduction of the mural thrombus
during the growth of thrombus, indicating reversibility of a
preexisting mural thrombus. It appears that continued cohesion of fresh
platelet-rich mural thrombus is thrombin dependent. r-Hirudin has a
superior antithrombotic effect compared with heparin at lower levels of
aPTT. Heparin exerts a dose-dependent inhibition of growth of thrombus
induced by a fresh mural thrombus. Aspirin alone or as an additional
drug to heparin has little effect on the progression of a thrombus at
high shear rates. Therefore, specific thrombin inhibition appears to
remain a promising treatment, but further studies are required to
substantiate these potential benefits in humans.
Received July 10, 1997;
revision received October 6, 1997;
accepted October 7, 1997.
© 1998 American Heart Association, Inc.
Basic Science Reports
Dissolution of Mural Thrombus by Specific Thrombin Inhibition With r-Hirudin
Comparison With Heparin and Aspirin
Abstract
Top
Abstract
Introduction
Methods
Results
Discussion
References
Background—The presence of residual
mural thrombus may predispose to recurrent thrombotic events in acute
coronary syndromes. The purpose of this study was to evaluate
the effects of antithrombotic and antiplatelet agents on a
preformed, fresh mural thrombus during growth of thrombus.
Key Words: thrombus • hirudin • thrombosis • platelet aggregation inhibitors
Introduction
Top
Abstract
Introduction
Methods
Results
Discussion
References
Thrombin plays
a pivotal role in response to rupture of an atherosclerotic plaque,
leading to coronary thrombosis in patients with acute
coronary syndromes.1 The major effects of
this serine protease include promotion of fibrin formation and further
activation of the coagulation cascade by prothrombinase complex. In
addition, thrombin is a potent stimulus for platelet activation,
induction of adhesion molecules by neutrophiles and monocytes, and
proliferation of vascular smooth muscle cells.2 3
Thrombus formation is modulated by local, rheological, and substrate
factors and systemic factors. Recent angiographic and experimental
studies demonstrated that a residual mural thrombus is a highly
thrombogenic surface.4 5 Residual mural thrombus
and persistent thrombin generation may predispose to recurrent
thrombotic events and reocclusion after
thrombolysis.6 7 8 9 10
Methods
Top
Abstract
Introduction
Methods
Results
Discussion
References
Animal Preparation
All procedures performed in this study were approved by the
institutional guidelines of the Animal Committee and conformed with the
American Heart Association guideline for animal research. Yorkshire
albino pigs were obtained from the same colony of pigs (n=14) from a
single local farmer (body weight, 29±3 kg). As described previously,
the pigs were sedated with ketamine (20 mg/kg IM) and atropine
(0.05 mg/kg IM), anesthetized with sodium pentobarbital (10
mg/kg IV), and intubated and ventilated (Harvard respirator, Harvard
Apparatus).9 Anesthesia
was maintained by repeat intravenous boli of sodium
pentobarbital with the minimal effective dose as previously described
(4 to 6 mg/kg IV).11
We used our previously characterized perfusion chamber,
which mimics the cylindrical shape of the blood
vessels.11 12 15 The substrate was placed on the
wall of the blood channel of the perfusion chamber and directly exposed
to fresh flowing blood as described below. We used a chamber with an
internal diameter of 0.1 cm, modeling local flow conditions typical of
medium-grade stenosis in coronary arteries (shear rate,
1690 s-1). At these flow conditions, blood can
be considered as having newtonian fluid properties with constant
viscosity. Shear conditions at the vessel wall were calculated from the
theoretical expression for shear rate given for a newtonian fluid in
tube flow.16
Tunica media prepared from pig aortas was used as a model of
severe arterial wall damage.17 To
quantify growth of thrombus on fresh thrombus formed on tunica media,
we modified the previously described perfusion conditions by using
blood from two pigs in the same experiment.9 One
pig served as a blood donor to form a fresh mural thrombus. The second
pig was treated with different antithrombotic treatment regimens and
used to quantify the growth of thrombus under identical flow
conditions.
The experimental groups were the same as in our previous
study.9 In brief, baseline perfusions were
performed to evaluate the amount of fresh thrombus (baseline, n=8) and
thrombus growth (control, n=8) in all experiments. Subsequently, the
second animal was given the selected treatment regimen, and perfusions
were continued for each group (n=12) to measure the effect of treatment
on fresh mural thrombus and growth of thrombus.
Radiolabeled platelets and fibrinogen are useful in studying
the rate of thrombus growth, as shown in our previous
study.9 However, the morphometric
analysis used in this study allowed evaluation and
characterization of the total thrombus area, including the preformed
fresh mural thrombus. After the perfusion, the aortic media strips were
removed from the chamber, fixed in 4%
paraformaldehyde, dehydrated with graded alcohol
series, embedded in paraffin, and sectioned. From each vessel, six
stepsections (4 µm thick) were taken at 100-µm intervals
parallel to the direction of flow. The sections were stained with
hematoxylin and eosin and trichrome. The single section with the
greatest amount of thrombus, coinciding with the longitudinal central
line of the surface exposed to blood, was systematically chosen from
each vessel for morphometric evaluation. Thrombus size was quantified
morphometrically by viewing the thrombus mass through the microscope at
100x magnification and tracing the outline using a side-tube
attachment to the microscope. The traced outline was then scanned into
a Macintosh computer, and areas were calculated using an image
processing software (NIH Image 1.44 for Macintosh). Thrombus size was
expressed as the surface area (mm2) normalized to
the length of the exposed segment (mm). Morphometric methods have been
previously validated for this model and other models and show a strong
correlation between the amount of 111In-labeled
platelets deposited on the media and the morphometrically assessed
thrombus size.18 19 20 21 All measurements were made
in a blinded fashion.
After each sequence of four perfusions, blood samples were
collected from each pig and evaluated for platelet count,
hematocrit, aPTT, and heparin levels. Heparin levels were
analyzed by an assay using a chromogenic substrate.
The test is based on the in vitro anti–factor Xa activity. The release
of pNA of the chromogenic substrate is inversely
proportional to the amount of heparin (IU/mL) present in the plasma
(Stachrom assay, Diagnostica Stago). The heparin standard
used in our heparin assays included three levels of UFH calibrators
(Hepanorm H; Diagnostica Stago).
Statistical comparison of data were carried out using StatView
II (Abacus Concepts). Between-group analysis were made using
one-way ANOVA, followed by Fisher PLSD and Scheffé's
F test to assess specific group differences. Thrombus area
was regressed against aPTT and plasma heparin concentrations with
linear regression. All values are presented as mean±SEM,
unless otherwise stated. P<.05 was considered
significant.
Results
Top
Abstract
Introduction
Methods
Results
Discussion
References
Thrombus Formation on Fresh Mural Thrombus
Mural thrombus was formed on an arterial media as
illustrated in Fig 1
. The total area of
thrombus formed on preformed fresh thrombus (control, n=32) and the
effect of various antithrombotic agents on growth of thrombus (n=12
each) are presented in Fig 2.
Fresh mural thrombus induced growth of thrombus by doubling of measured
thrombus size in untreated groups (0.14±0.03 and 0.28±0.07
mm2/mm, respectively).
View larger version (67K):
[in a new window]
Figure 1. Photomicrographs of severely injured porcine
aortic vessel wall (Tunica media) exposed to flowing blood at high
shear rate. Selected sections representative of mean
thrombus area shown in Fig 2 
, illustrating a mural thrombus (A), growth
of thrombus triggered by a preformed mural thrombus (control, B), and
growth of thrombus onto fresh mural thrombus from a pig treated with 1
mg/kg hirudin (C). Note small amount of thrombus in C, indicating
complete inhibition of thrombus growth and reduction of the size of
preformed mural thrombus. Trichrome, 250x.
View larger version (21K):
[in a new window]
Figure 2. A, Differential effects of antithrombotic regimens
on mean thrombus area during growth of thrombus (control, hatched bar)
triggered by a fresh mural thrombus at high shear rate (baseline, open
bar). Vertical lines, SEM. Thrombus area in animals treated with
hirudin was significantly lower compared with baseline and the highest
heparin group (*P<.001 versus baseline,
§P<.001 versus heparin 250 IU/kg). Heparin showed a
dose-dependent effect on growth of thrombus. Aspirin had no significant
effects on growth of thrombus. B, Growth of thrombus as a percentage of
mural thrombus of the same experimental groups in A. Note a significant
reduction of mural thrombus during treatment with r-hirudin, indicating
dissolution of preformed mural thrombus. ).
Direct thrombin inhibition by hirudin significantly reduced growth of
thrombus compared with control and even compared with the highest
concentration of heparin (P<.001 and P<.001,
respectively; Fig 2). ) and aPTT levels (r=.65,
P=.0001).
View larger version (15K):
[in a new window]
Figure 3. Relation between thrombus area and heparin levels
(IU/mL) during growth of thrombus onto a mural thrombus in pigs treated
with heparin doses of 50, 100, or 250 IU/kg. The significant inverse
relations is shown. Two values of heparin levels in the group receiving
50 U heparin are missing; one value is hidden due to overlapping
results in the top left cluster.
Platelet count and hematocrit were assessed every hour
during baseline perfusions and during the treatment period. There was a
slight nonsignificant reduction in platelet count from 447±18 to
421±15x103/µL during the treatment phase
compared with the baseline perfusion period. The hematocrit remained
unchanged from 31±0.8% to 30±1.0%. Platelet counts and
hematocrit were not significantly different between treatment
groups.
Discussion
Top
Abstract
Introduction
Methods
Results
Discussion
References
The present study revealed that specific thrombin
inhibition with r-hirudin induced dissolution of preformed mural
thrombus in an experimental model of deep injury and platelet-rich
thrombosis. This observation of dissolution of fresh mural thrombus by
specific thrombin inhibition alone without concomittant administration
of a fibrinolytic agent represents a substantial extension of
our previous findings9 and underscores the
importance of thrombin in cohesion of fresh platelet thrombus. 
2-antiplasmin to fibrin
monomers, which is dependent on the activation of factor XIII by
thrombin, seems to be essential for thrombolysis
resistance of fibrin clots.36 37 In addition,
specific thrombin inhibition may facilitate endogenous
fibrinolysis by lowering PAI-1 secretion of
endothelial cells and inhibiting the release of PAI-1
from platelets.38
Acknowledgments
This work was supported in part by NIH grant HL-38933 and CICYT
grant SAF-94/0712. Dr Meyer is supported by grant 32–47077.96 from the
Swiss National Foundation of Science.
References
Top
Abstract
Introduction
Methods
Results
Discussion
References
This article has been cited by other articles:
 |
|
 |
|
  V. Fuster, P. R. Moreno, Z. A. Fayad, R. Corti, and J. J. Badimon Atherothrombosis and High-Risk Plaque: Part I: Evolving Concepts J. Am. Coll. Cardiol., September 20, 2005; 46(6): 937 - 954. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. Vilahur, E. Segales, E. Salas, and L. Badimon Effects of a Novel Platelet Nitric Oxide Donor (LA816), Aspirin, Clopidogrel, and Combined Therapy in Inhibiting Flow- and Lesion-Dependent Thrombosis in the Porcine Ex Vivo Model Circulation, September 21, 2004; 110(12): 1686 - 1693. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D.A. Vorchheimer and V. Fuster Thrombin inhibitors in acute coronary artery disease Eur. Heart J., August 1, 2002; 23(15): 1142 - 1144. [Full Text] [PDF]
|
|
|
|
 |
|
 H. Luciardi, S. Berman, J. Muntaner, F. De La Serna, and R. Altman Facilitated Thrombolysis: Dethrombosis? Clinical and Applied Thrombosis/Hemostasis, April 1, 2002; 8(2): 133 - 138. [Abstract] [PDF]
|
|
|
|
|
|
H. Mehta and B. J. Meyer r-Hirudin for percutaneous coronary interventions--time to reconsider? Eur. Heart J., January 2, 2002; 23(2): 95 - 97. [Full Text] [PDF]
|
|
|
|
|
|
S.R Mehta, J.W Eikelboom, H.-J Rupprecht, B.S Lewis, M.K Natarajan, C Yi, J Pogue, and S Yusuf Efficacy of hirudin in reducing cardiovascular events in patients with acute coronary syndrome undergoing early percutaneous coronary intervention Eur. Heart J., January 2, 2002; 23(2): 117 - 123. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Badimon, G. Vilahur, S. Sanchez, and X. Duran Atheromatous plaque formation and thrombogenesis: formation, risk factors and therapeutic approaches Eur. Heart J. Suppl., August 1, 2001; 3(suppl_I): I16 - I22. [Abstract] [PDF]
|
|
|
|
|
|
Y. Cottin, M. Kollum, R. Chan, B. Bhargava, Y. Vodovotz, and R. Waksman Vascular repair after balloon overstretch injury in porcine model effects of intracoronary radiation J. Am. Coll. Cardiol., October 1, 2000; 36(4): 1389 - 1395. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Moshfegh, M. Redondo, F. Julmy, W. A. Wuillemin, M. U. Gebauer, A. Haeberli, and B. J. Meyer Antiplatelet effects of clopidogrel compared with aspirin after myocardial infarction: enhanced inhibitory effects of combination therapy J. Am. Coll. Cardiol., September 1, 2000; 36(3): 699 - 705. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Peter, J. Graeber, S. Kipriyanov, M. Zewe-Welschof, M. S. Runge, W. Kubler, M. Little, and C. Bode Construction and Functional Evaluation of a Single-Chain Antibody Fusion Protein With Fibrin Targeting and Thrombin Inhibition After Activation by Factor Xa Circulation, March 14, 2000; 101(10): 1158 - 1164. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. H. Chesebro and J. J. Badimon Platelet Glycoprotein IIb/IIIa Receptor Blockade in Unstable Coronary Disease N. Engl. J. Med., May 21, 1998; 338(21): 1538 - 1541. [Full Text]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||