normal and post-heart attack pressure-volume loop?

Question

can somebody please explain me the the difference between normal and post heart attack presuure volume loop? what happened to left ventricular volume and pressure? what happens to phases (isovolumetric contraction, ejection of blood, isovolumetric relaxation? is there any changes occur in stroke volume or ejection fraction?

Answer 1

This is a good question. When someone has a heart attack, there is dead myocardium. The part of the myocardial wall (especially if it is the left ventricle) cannot contract and often with time dilates under the intra-ventricular pressure. The pressure -volume loop will shift to the right. There will be a dearth of pre-load and decreased contractility. If the heart is still ischemic, there will be restrictive problems also, that is increased diastolic stiffness and decreased ejection fraction, also lack of pre-load and lack of contractility. So because of decreased stroke work, the area inside the loop is smaller.