A patient has a stenotic mitral valve which has a reduced effective orifice area of 1.0 cm^2. The systolic ejection period is 330 milliseconds with a heart rate of 70 beats/min. The mean aortic gradient (as measured by echocardiography) is 25 mmHg. Using the Gorlin equation, estimate the pressure gradient required to maintain a cardiac output of 4500 mL/min.