tailieunhanh - Diastolic Heart Failure – part 2

Ví dụ điển hình là trung tâm trong hẹp động mạch chủ, tim tăng huyết áp, và trái tim tu sửa của đối tượng trong độ tuổi. Sự khác biệt giữa distensibility, tuân thủ, và các vấn đề kích thước khoang | 26 . Gillebert and . Leite-Moreira Figure top . Typical examples are the heart in aortic stenosis the hypertensive heart and the remodeled heart of the aged subject. The distinction between distensibility compliance and cavity size matters however when changes in the descriptors of the diastolic PV relation go in opposite directions. This is illustrated by SHF for example the ischemic cardiomyopathy Figure bottom . These hearts have an enlarged LV cavity but operate on a steep portion of their PV curve with small increases in volume leading to sharp increases in diastolic LV pressures. There is an apparent increase in distensi-bility 14 which could be explained solely by an increase in the constant A instead of an increase in the intercept P0 this actually means an increase in LV size but no increase in LV distensibility. Figure . End-dastolic pressure-volume relations in diastolic and chronic systolic heart failure. Top The relation is shifted leftward and upward and is steeper. This is the manifestation of smaller cavity size and reduced compliance. Bottom In chronic systolic heart failure the relation is shifted rightward and is steeper. Cavity size is increased and compliance is reduced. The hallmark of heart failure in both conditions is the reduced compliance and the steep curve accordingly. The ventricle operates on a steep portion of the curve because of a combination of overfilling and decreased compliance of the ventricle. These severely diseased hearts are no more able to work at smaller volumes and respond to exercise elevated cardiac output and increased cardiovascular volumes by pulmonary congestion and symptoms. William Little recently referred to this situation as diastolic dysfunction beyond disten-sibility pointing out that in addition to dis-tensibility and compliance issues these hearts developed less elastic recoil and disturbed diastolic acceleration of blood flow from the mitral inflow to the LV For practical purposes