Relation between myocardial beta-adrenergic receptor and left ventricular function in patients with left ventricular volume overload due to chronic mitral regurgitation with or without aortic regurgitation.

The relation between myocardial beta-adrenergic receptor and left ventricular (LV) function was studied in 10 patients, aged 41 to 61 years (average 51), with LV volume overload mainly due to chronic mitral regurgitation. Beta-adrenergic receptors were examined using crude membrane in LV papillary muscle obtained at mitral valve replacement. Cardiac function was evaluated at preoperative cardiac catheterization with the interval to surgery of 1 to 33 months (average 7). Beta-adrenergic receptor density in 7 patients with New York Heart Association class II or III congestive heart failure was higher than that in 3 patients with class IV heart failure (59 +/- 19 vs 37 +/- 3 fmol/mg protein, p less than 0.05). Beta-adrenergic receptor density showed a positive correlation with end-systolic stress/end-systolic volume index ratio, the index for contractile function (p less than 0.005). Other parameters such as cardiac index, pulmonary artery wedge pressure and LV ejection fraction had no significant correlation to beta-adrenergic receptor. The results demonstrated that increases in symptom and LV dysfunction, particularly of the contractile state, was associated with decreased myocardial beta-adrenergic receptor density from possible down-regulation in patients with chronic mitral regurgitation with or without aortic regurgitation.