Abstract
The density of cardiac β-adrenoceptors (Bmax) was measured in eighteen patients [2 with atrial septal defect (ostium secundum), 4 with aortic valve disease, 3 with mitral valve disease, 1 with aortic and mitral valve disease, 5 with a history of myocardial infarction, and 3 with angina pectoris] following mild to moderate cardiac failure. Measures were obtained by cardiac catheterization prior to cardiac surgery and also during the surgical procedures. On the basis of symptoms immediately preceding surgery, the severity of the condition in each patient was categorized as either Class I (n=5) or Class II (n=13) following the New York Heart Association (NYHA) functional classification system. The Bmax was measured using right atrial appendage tissue obtained during cardiac surgery. [125I]-iodocyanopindolol was used for the assay. The Bmax of atrial cell membranes in patients with NYHA class II was significantly lower than that of class 1 (34.1±2.5 vs 55.4±9.3 fmol/mg protein, M±SE, p<0.05). Correlation coefficients between the Bmax and hemodynamic parameters measured just prior to cardiac surgery were examined, but only that between Bmax and the minimum value of the time derivative of left ventricular pressure (max negative dp/dt) was significant (r=-0.552, p<0.05). Further study is needed to understand and clarify the relationship between Bmax and dp/dt min.
