In some cases, the aortic valve does not close tightly, causing blood to leak backward into the left ventricle.Coarctation of the aorta (a congenital narrowing in the region of the ductus arteriosus) has also been associated with BAV. Pathophysiology
Fusion of aortic valve leaflets occurs most commonly (≈80%) between the right coronary and left coronary leaflets (RL), which are the anterior leaflets of the aortic valve. Fusion also occurs between the right coronary and noncoronary leaflets (RN, ≈17%), and least commonly between the noncoronary and left coronary leaflets (≈2%). In comparison to other fusion patterns, RN leaflet fusion has a stronger association with future complications such as aortic valve regurgitation and stenosis. However, all fusion patterns associate with a specific area or areas of dilated enlargement in either the root of the ascending aorta, the ascending aorta, or the transverse aortic arch. Hemodynamics
Identifying hemodynamic patterns in the aorta after left ventricle systole aids in predicting consequential complications of bicuspid aortic valve. The patient-specific risk of developing complications such as aortic aneurysms is dependent on the particular aortic leaflet fusion pattern, with each pattern varying in 4D MRI measurements of wall shear stress (WSS), blood flow velocity, asymmetrical flow displacement and flow angle of the aorta.BAV outflow is helical and occurs at high velocities (>1 m/s) throughout the ascending aorta. This is potentially more damaging to the aorta in comparison to the streamline flow and short-lived burst of high velocity at the beginning of the aorta, as seen within a healthy tricuspid valve.
COMT eliminates biologically active catechols present in catecholamines (dopamine, norepinephrine, and epinephrine) and their hydroxylated metabolites. When administered with a decarboxylase inhibitor, COMT acts as the major metabolizing enzyme for levodopa and metabolizes it to 3-methoxy-4-hydroxy-L-phenylalanine (3-OMD) in the brain and in the periphery.For the treatment of Parkinsons disease, entacapone is given as an adjunct to levodopa and an aromatic amino acid decarboxylase inhibitor, carbidopa. Entacapone inhibits COMT in the periphery (but not, or at most marginally, in the brain) and the metabolism of levodopa, thus increasing plasma levels of levodopa and causing more constant dopaminergic stimulation in order to reduce the signs and symptoms presented in the disease. Pharmacokinetics
Absorption
The time to highest blood plasma concentrations is approximately one hour. The substance undergoes extensive first-pass metabolism. Absolute oral bioavailability (F) is 35%. Distribution
The volume of distribution  (Vd) after intravenous injection is approximately 20 liters. 98% of the circulating entacapone is bound to serum albumin, which limits its distribution into tissues. Metabolism and elimination
Entacapone is primarily metabolized to its glucuronide in the liver, and 5% are converted into the Z-isomer. It has a half-life of approximately 0.3–0.7 hours, with only 0.2% being excreted unchanged in the urine. References
External links
"Entacapone". Drug Information Portal. U.S. National Library of Medicine.