The Bernoulli principle, specifically the simplified or modified Bernoulli equation, is a fundamental tool in Doppler echocardiography that allows sonographers and cardiologists to estimate the pressure gradient, or difference in pressure, across a narrowed area like a stenotic heart valve. The simplified equation states that the pressure gradient in millimeters of mercury equals four times the velocity squared. For example, if the peak blood velocity across an aortic valve is 4 meters per second, the estimated pressure gradient is 64 mmHg, indicating severe stenosis. This calculation is used routinely in echocardiography to grade the severity of valve stenosis and to estimate pulmonary artery pressures.
Sonography Term