A simple cardiac contractility computer

A single-purpose analogue-computing device is described for the online assessment of the contractile state of the human myocardium from the left ventricular pressure (P_lv) data available during routine cardiac catheterisation. Due attention has been paid to the design of the computer circuits so that they will not process pressure phenomena outside the isovolumic contractile period. Either a (left( {frac{1}{{P_{lv} }}frac{{dP_{lv} }}{{dt}}} right)_{max} ) or a plain (left( {frac{{dP_{lv} }}{{dt}}} right)_{max} ) index is presented on a digitalvoltmeter display, thus obviating the need for any graphical extrapolation or additional computation.