This eccentric outflow from the BAV results in blood hitting and reflecting off the aortic wall in a non-streamline fashion. The specific zones where blood hits is dependent on the varying BAV leaflet fusion patterns and consequently correlates with increases in WSS. WSS measurements in RL fusion indicate an increase in pressure applied predominantly to the right-anterior side of the vessel wall, while RN fusion increases WSS on the right-posterior wall. The resulting rise in WSS is supported by the asymmetrical displacement of blood flow produced by an increased angle of outflow from the BAV. Displacement is measured as the distance in millimeters from the center of the aorta to the center of the high velocity outflow. Blood does not flow centrally through the aorta in BAV, but along the right-anterior and right-posterior vessel wall for RL and RN leaflet fusion respectively. Aortic disease
Identification of hemodynamics for RL, RN, and left coronary and noncoronary leaflet fusion patterns enables detection of specific aortic regions susceptible to dysfunction and the eventual development of disease. Specifically, RL and RN fusion patterns are more likely to develop into these aortic disease states. The blood flow information associated with RL fusion causes dilation of the mid-ascending aorta, while RN fusion is associated with dilation in the root, distal ascending aorta and transverse arch. BAV helical and high velocity outflow patterns are consistent with aortic dilation hemodynamics seen in those with tricuspid aortic valves.
However, it is the increase and variance in WSS and flow displacement in BAV that demonstrate the importance of aortic leaflet morphology. Flow displacement measurements taken from 4D MRI may be best for detecting irregularities in hemodynamics. Displacement measurements were highly sensitive and distinguishable between different valve morphologies. Hemodynamic measurements from 4D MRI in patients with BAV are advantageous in determining the timing and location of repair surgery to the aorta in aortopathy states.Most patients with bicuspid aortic valve whose valve becomes dysfunctional will need careful follow-up and potentially valve replacement at some point in life. Regular EchoCG and MRI may be performed.If the valve is normally functioning or minimally dysfunctional, average lifespan is similar to that of those without the anomaly. Diagnosis
A bicuspid aortic valve can be associated with a heart murmur located at the right second intercostal space. Often there will be differences in blood pressures between upper and lower extremities. The diagnosis can be assisted with echocardiography or magnetic resonance imaging (MRI). Four-dimensional magnetic resonance imaging (4D MRI) is a technique that defines blood flow characteristics and patterns throughout the vessels, across valves, and in compartments of the heart. Four-dimensional imaging enables accurate visualizations of blood flow patterns in a three-dimensional (3D) spatial volume, as well as in a fourth temporal dimension. Current 4D MRI systems produces high-resolution images of blood flow in just a single scan session.