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

after a heart attack, the damaged myocardium won't pump as well, and it also won't relax as well- the scarring prevents adequate relaxation, so the diastolic phase (isovolumetric relaxation) will be blunted. also, the entire contraction phase will be blunted as well, so you have decreased stroke volume and ejection fraction. the LV pressure is sometimes lower, but not always- the remaining myocardium can usually generate enough pressure unless there was pretty extensive infarction. the LV volume is usually normal, unless an aneurysm developed at the site of the infarction- that's a ballooning out of the myocardial wall at an area of weakness.

Answer 2

After a heart attack, there is dead myocardium. This dead tissue can no longer contract and often with time dilates (especially in the left ventricle). So the post-heart attack loop is shifted to the right. A larger pre-load is needed and there is impaired contractility. If the heart is still ischemic, you will have restrictive problems because of increased diastolic stiffness, an increase in the slope of the EDPVR, small EDV, higher EDP and small ejection volume. This is also because of decreased pre-load and impaired contractility. The area in the loop is the stroke work. The smaller the loop, the smaller the stroke work.

Answer 3

anyone can have a heart attack....heart failure is a completely different disease. heart attack is caused by a blockage in the coronary arteries due to buildup of plague. failure is when the actual heart muscle is unable to pump effectively and the lungs fill with fluid (often times proceeded by high blood pressure)