THE EFFECTS OF AFTERLOAD REDUCTION ON MYOCARDIAL CARBON 11-LABELED ACETATE KINETICS AND NONINVASIVELY ESTIMATED MECHANICAL EFFICIENCY IN PATIENTS WITH DILATED CARDIOMYOPATHY

Methods and Results. With echocardiography and dynamic carbon 11-label ed acetate (C-11 acetate) positron emission tomographic imaging, C-11 acetate kinetics and a parameter that estimates mechanical ventricular efficiency (the work metabolic index) were defined in eight patients with dilated cardiomyopathy. The effect of afterload reduction with ni troprusside on these parameters was evaluated in six of these patients . Nitroprusside increased stroke work index but decreased the C-11 cle arance rate. The work metabolic index determined noninvasively increas ed and correlated well with an invasive,approach. The work metabolic i ndex was inversely correlated with systemic vascular resistance. Nitro prusside shifted this relationship upward and to the left. Conclusion. This method of estimating efficiency is feasible and may represent a unique noninvasive approach for the evaluation of cardiac performance and responses to therapy.