“What Is An Aortic Valve Gradient?” Asks Jack
By Adam Pick on October 5, 2008
At 64, Jack has recently been diagnosed with severe aortic valve stenosis. Jack writes, “Adam – I’m like a deer in headlights right now. I need aortic replacement soon. I’m curious, the doc mentioned an aortic valve gradient following my echocardiogram. What the heck does that mean? Thanks for all you do, Jack.”
Jack asks a good question about aortic valve gradients (also known as AVG). In fact, I have never received a question about aortic valve gradients, so I just spent some time researching this diagnostic measure for valvular stenosis.
According Cardiovascular Physiology, stenosis of the aortic valve leads to a pressure gradient across the valve during the time in which blood flows through the valve opening. This aortic valve gradient is expressed as an increase and decrease on each side of the defective valve. The magnitude of the pressure gradient depends on the severity of the stenosis and the flow rate across the valve.
Aortic stenosis is characterized by the left ventricular pressure being much greater than aortic pressure during left ventricular ejection (see the shaded gray in figure above). Normally, the pressure gradient across the aortic valve is very small (a few mmHg); however, the pressure gradient can become quite high during severe stenosis (>100 mmHg). The aortic valve gradient results from both increased resistance (related to narrowing of the valve opening) and turbulence distal to the valve.
If that was too scientific for you, here is my layman’s interpretation… In patients with aortic stenosis, the left ventricle has to “work overtime” to compensate for the constricted blood flow through the valve. The aortic valve gradient increases as a result. Over time, this can severely damage the patient’s left ventricle as it thickens and dilates. This is exactly why I needed an aortic valve replacement operation.
According to cardiologist, Dr. Robert Matthews, heart catheterization can also be used to judge severity of the valve stenosis (if undeterminable non-invasively) by recording the aortic valve gradient across the valve, estimating the stenotic area , evaluating the left ventricular function and to determine if coronary artery disease is concurrently present.
I hope this helps explain more about the gradient of the aortic valve.
Keep on tickin!