Final answer:
Contractility on echo can be measured by recording EDV and ESV on an echocardiogram and calculating the difference. Contractility is the force of the heart muscle contraction and is influenced by positive and negative inotropic factors.
Step-by-step explanation:
Contractility refers to the force of the heart muscle contraction, which affects stroke volume (SV) and end-systolic volume (ESV). It can be measured on an echocardiogram by recording the end-diastolic volume (EDV) and ESV and calculating the difference (SV = EDV - ESV). SV can also be measured using a specialized catheter, but this is an invasive procedure. Contractility is influenced by factors such as positive inotropic factors (which increase contractility) and negative inotropic factors (which decrease contractility).