There is an established practice of using the electrical<unk>  of blood (PV loops) in heart ventricles to determine the instantaneous volume of the ventricle. This technique involves inserting a tetra-polar catheter into the ventricle and measuring<unk> . This measured<unk>  is a combination of blood and muscle and various techniques are used to identify the blood<unk>  from the total measured<unk> . Blood<unk>  can then be converted to volume using a linear (Baan) or a non-linear (Wei) relationship that relates<unk>  to volume.
Admittance and conductance in cardiac performance
Cardiac excitation-contraction coupling
Cardiac rhythmicity
Cardiac action potential
Diastolic function
Myocardial contractility
Intermuscular coherence
Skeletal-muscle pump