Estimation of active myocardial force development: a feasibility study in a potentially clinical setting

The quantitative assessment of (regional) myocardial function remains an important goal in clinical cardiology. We have set out this study to develop a method to estimate myocardial contractility, which can be represented by the active force development in the myocardium during the systolic phase of the cardiac cycle. To measure the active force development we coupled a model of cardiac mechanics, with simplified geometry, to haemodynamic data and deformation data, obtained from ultrasonic strain(-rate) imaging. The active stress is estimated from the difference of the total estimated wall stress and the passive stress estimated during diastole. This methodology was validated in ten pigs. The obtained active force time courses appear realistic and compare to results obtained in isolated muscle experiments. The peak active tension was reached at 113±14 ms after the onset of the QRS complex, i.e. at 1/3 of systole and reached a peak value of 46±9 kPa. The acquisition setup used in this feasibility study could be transferred as is to the clinical setting of a human cathlab.