Patent ID: 6887207

Claim:
A method of deriving an index of ventricular afterload presenting resistance to ejection of blood from a ventricle during a blood ejection phase comprising: obtaining a set of ventricular pressure values of blood pressure within a ventricle at sample times during the blood ejection phase of the ventricle; determining the peak positive pressure value P b , the peak positive derivative pressure dP/dt PP and the peak negative derivative pressure dP/dt NP from the set of ventricular pressure values; determining the sample time t b of peak positive pressure, the sample time t a of the peak positive derivative pressure dP/dt PP , and the sample times t c of the peak negative derivative pressure dP/dt NP from the sample times associated with the set of ventricular pressure values; and calculating an index Î± of the relative timing of peak positive pressure P b in the blood ejection phase in accordance with the formula Î±=(t b âˆ’t a )/(t câˆ’t a ), wherein the severity of ventricular afterload is proportional to the value of index Î± in the range between 0 and 1.