Platelet Function And Aggregometry In Patients With Aortic Valve Stenosis
Status:
Completed
Trial end date:
2005-09-01
Target enrollment:
Participant gender:
Summary
It is known that patients with aortic stenosis, including those undergoing cardiac surgery
for this problem, are prone to developing bleeding problems, particularly of the
gastrointestinal tract. It is believed that the shear stress associated with blood flow
through the abnormal aortic valve results in abnormal hemostasis. Abnormalities include
increased proteolysis of the von Willebrand factor (vWF) and increased binding of the high
molecular weight multimers of vWF to platelet membranes with subsequent inappropriate
platelet aggregation. Thus, appropriate aggregation of circulating platelets is impaired.
Cardiac surgery is associated with significant alterations in hemostasis. Patients undergoing
cardiac surgery consume a significant percent of available blood products throughout the
United States and are subjected to various and numerous risks associated with blood product
transfusion. In addition, excessive postoperative bleeding is a common cause for the need to
surgically re-explore the chest cavity in patients who have just undergone cardiac surgical
procedures. Such additional surgery carries further cost and risk. Following surgical
correction of aortic valve stenotic pathology, associated vWF abnormalities appear to
reverse. However, this process can take several days. Although all cardiac surgical patients
are at risk for postoperative bleeding, patients undergoing aortic valve surgery for aortic
stenosis may be particularly at risk for this postoperative complication. In addition,
patients with aortic valve stenosis who undergo noncardiac surgery may have a predisposition
to bleeding because of similar underlying shear stress induced abnormal vWF and platelet
function. The proposed study is a trial to evaluate the effectiveness of 2 different
antifibrinolytic drugs in ameliorating the hemostatic defect associated with aortic stenosis.
Aprotonin, an antifibrinolytic agent which also has platelet preserving actions4, will be
compared to the currently used anti-fibrinolytic, epsilon aminocaproic acid (EACA).