A11

To calculate the DP/DT using the MR tracing, take the pressure at 3m/s and 1m/s (so 36mmHg-4mmHd) and divide by the time it takes to go across this interval. Normal dp/dt is >1200, borderline is 1000 mmHg to 1200 and abnormal is less than 1000. do 36-4 x 1000/delta t in ms. the 1000 converts to sec.