Relation between diastolic left ventricular wall stress and strain in man.

Continuous measurements of left ventricular pressure were made by micromanometer and of dimension and posterior wall thickness by echocardiography in 23 patients with cardiomyopathy or valvular heart disease. From these, the stress-strain relation of a region of myocardium in the posterior wall was derived throughout diastole. This was complex, showing an early diastolic period of rapid change corresponding with the end of ventricular contraction, a middle period when wall stiffness was very low, and a late period when wall stiffness was finite and relatively constant. Stress-strain characteristics in this last period were related to cardio- graphic evidence of left ventricular hypertrophy: in its absence the average value of elastic modulus was 260g cm-2, while in its presence it was 930g cm-2. The stress-strain characteristics of left ventricular myocardium were dependent on the previous contraction and could be related to the pattern offilling throughout diastole.