Left atrial mechanical function in patients with essential hypertension.

OBJECTIVE: This study was carried out to assess the left atrial (LA) mechanical function in patients with essential hypertension with two-dimensional echocardiography by means of left atrial volume measurements.

METHODS: LA volumes were measured echocardiographically in 36 untreated hypertensive patients and 20 age-sex-matched healthy controls according to biplane area-length method. LA volume measurements were done at the time of mitral valve opening (Vmax), at the onset of atrial systole (p wave at the electrocardiography = Vp) and at closure (Vmin). All volumes were indexed for body surface area, and the following left atrial emptying functions were calculated: LA passive emptying volume = Vmax -Vp, LA passive emptying fraction = LA passive emptying volume /Vmax, conduit volume = left ventricular stroke volume-(Vmax-Vmin), LA active emptying volume = Vp-Vmin, LA active emptying fraction = LA active emptying volume /Vp, LA total emptying volume = (Vmax-Vmin), LA total emptying fraction = LA total emptying volume /Vmax.

RESULTS: Vmax (p < 0.01),Vmin (p < 0.005) and Vp (p < 0.001) were significantly greater in hypertensives than in controls. Although LA passive emptying volume (p < 0.001), LA passive emptying fraction (p < 0.001), conduit volume (p < 0.005) and LA total emptying fraction (p < 0.05) were found to be significantly lower in hypertensives than in controls, LA active emptying volume (p < 0.001) and LA active emptying fraction (p < 0.01) were found to be significantly greater in hypertensives than in controls. LA total emptying volume (p > 0.05) was similar in both groups.

CONCLUSION: The results of the present study indicate that chronic hypertension is associated with an increased in left atrial volumes, a decrease in left atrial passive emptying function, and an increase systolic pump function. Increased left atrial pump function represents a compensatory mechanism in hypertensive patients with left ventricular hypertrophy.