Prevention of Postoperative Thromboembolic Complications of Cardiac Valve Replacement
Pharmacology
Platelet Aggregation Inhibitor (see Coagulopathy, [[Coagulopathy]]): inhibition of platelet secretion
Mechanisms
Inhibition of platelet (and endothelial and RBC) adenosine reuptake -> increase in local adenosine concentration -> adenosine binding to platelet A2-receptor -> stimulation of platelet adenylate cyclase and increased platelet cAMP
Phosphodiesterase inhibition (in various tissues): since phosphodiesterase degrades cAMP, this increases cAMP
Inhibition of cAMP-PDE is weak
More potent inhibition of cGMP-PDE, augmenting the increase in cGMP produced by nitric oxide
Hemodynamic Effects
Dose-related decrease in systemic vascular resistance (SVR) -> hypotension
Acute IV Dipyridamole Administration: may worsen regional myocardial perfusion distal to partial occlusion of coronary arteries -> this provides the rationale for using Persantine in coronary stress testing