Relationship of Inotropic Effects of Stimulation of β₁- and β₂-Adrenergic Receptors of Isolated Myocardial Fragments with Echocardiography Parameters in Coronary Heart Disease

We studied the relationship of inotropic responses of the isolated myocardium to stimulation of β₁-and β₂-adrenergic receptors (β-AR) with echocardiography parameters in 28 patients with coronary heart disease (CHD). Myocardial fragments (trabeculae of the right atrial appendage) were obtained during coronary artery bypass surgery. The inotropic response of the trabeculae was assessed in an isometric mode. Stimulation of β₁-and β₂-AR with agonists was performed against the background of preliminary α-AR blockade. In case of preserved ejection fraction, significant inotropic response of the trabeculae (135 (112; 154)% from the initial contraction amplitude) was observed after β₁-AR stimulation, while in reduced ejection fraction, its significant increase was observed after β₁-AR stimulation (126 (112; 170)% from the initial contraction amplitude). In patients with preserved and reduced ejection fraction, the correlations between the inotropic responses of the trabeculae to β₁-and β₂-AR stimulation and echocardiography parameters were different. The revealed differences reflect the degree of cardiac remodeling under condition of the studied pathology.