Acute changes of left atrial distensibility in congestive heart failure

AbstractBackground: Investigations of the left atrial (LA) distensibility have revealed that it plays a major role in atrial function; however, LA distensibility has not as yet been studied in congestive heart failure (CHF).Hypothesis: The study was undertaken to determine the effects of acute administration of esmolol, isosorbide dinitrate, dobutamine, and normal saline infusion on LA dimension, pressure, and distensibility.Methods: The study included 23 patients with CHF (18 with ischemic heart disease and 5 with idiopathic dilated cardiomypathy). Left atrial diameters (D) and pressures (P) were recorded at rest and thereafter during acute tests. P and D data during the ascending limb of the V loop were fitted to the exponential function P = b·ead, where a is the passive elastic chamber stiffness constant and b is the elastic constant. The instantaneous diastolic LA distensibility (IDLAD) was calculated as 1/(dP/dD)= 1/a·P.Results: The constant, a, increased significantly after normal saline and esmolol infusion (p<0.001), while it significantly decreased after isosorbide dinitrate (p <0.001) and dobutamine administration (p <0.05) compared with baseline. Instantaneous diastolic LA distensibility (in mm/Hg) was 0.16 at baseline; it significantly increased after isosorbide dinitrate (0.32) and dobutamine (0.24) administration, while it significantly decreased after normal saline (0.11) and esmolol (0.12) infusion (p <0.001 for all).Conclusion: In CHF, LA distensibility may acutely increase with vasodilators or inotropics or may decrease with beta blockade or volume loading.