CARDIAC-HYPERTROPHY AND SHAPE - A NONINVASIVE INDEX

The wall thickness (W) of the left ventricle is examined as a possible long-term index of contractility, Two possible stimuli for increases in W are extrinsic pressure overload and cardiomyopathy. This results in the concentric hypertrophy growth pattern, This pattern of hypertro phy has been successfully explained using the wall stress theory of hy pertrophy, In this study, a mathematical model of cardiac growth is us ed to solve directly for the change in W with respect to myocardial lo ss of contractility, This model supports the theory that rate of myoca rdial oxygen consumption is regulated at the myocyte in the face of ex trinsic overloads or intrinsic functional impairment, It is found that W increases for both normal physiological hypertrophy and cardiomyopa thy, as observed in the clinic, To differentiate abnormal function, th e ventricular shape is examined with respect to its similarity to a pe rfect sphere, It is found that cardiomyopathy induces a more spherical shape of ventricle with respect to a normal ventricle and exercise-tr ained hypertrophy. It is proposed that ventricular wall thickness or w all thickness to diameter ratio together with comparison to a spherica l shape may be a useful indicator of chronic cardiomyopathy.