Congestive Heart Failure
Increasing degrees of left ventricular filling impairment modulate left atrial function in humans

https://doi.org/10.1016/S0002-9149(98)00452-4Get rights and content

Abstract

We sought to investigate the changes in atrial reservoir, pump, and conduit functions that are associated with increasing degrees of left ventricular filling impairment. In 13 patients with an impaired relaxation type of filling and in 15 with restrictive patterns, the left atrial volume curve was constructed combining Doppler and 2-dimensional echocardiography. Nine normal subjects served as controls. Left atrial reservoir (defined as [maximum − minimum atrial volume] minus the amount of blood flow reversal in the pulmonary veins with atrial contraction), pump (defined by the volume of blood that enters the ventricle with atrial contraction), and conduit functions (defined as left ventricular filling volume − [left atrial reservoir plus pump volume]) were computed and each expressed as a percentage of ventricular filling volume. The atrial reservoir function was higher in the impaired relaxation group than in normal subjects (49 ± 8% vs 38 ± 8%, p <0.01) but markedly lower in the restrictive group (27 ± 8%, p <0.05). The reverse was true for conduit function, exaggerated in restrictive group (54 ± 12% vs 36 ± 11% in normal subjects, p <0.01) but minimized in patients with an impaired relaxation type of filling (14 ± 9%, p <0.001). The atrial pump contributed 19 ± 6% of ventricular filling volume in restrictives, 26 ± 3% in normals (p <0.01), and 38 ± 4% (p <0.001) in the impaired relaxation group. We conclude that increased atrial response to early-stage left ventricular filling impairment is characterized by augmented reservoir and pump functions, according to a Starling mechanism, which becomes hardly effective at end-stage ventricular dysfunction when the limits of the atrial preload reserve are reached. At this stage, conduit in the atrium takes precedence.

Section snippets

Patients

The study group consisted of 28 subjects in sinus rhythm with satisfactory transthoracic pulmonary venous and mitral valve flow velocity recordings, grouped according to 2 typical patterns of ventricular filling: impaired relaxation and restrictive pattern11 defined on the basis of the ratio between the Doppler peak of early to late diastolic mitral flow velocity (E/A) as well as the early mitral wave deceleration time (Tde) measured as the time interval from the E peak to the zero intercept of

Results

Clinical data from the 28 patients, along with the 9 normal subjects, are reported (Table I). At cardiac catheterization left ventricular end-diastolic pressure averaged 12.8 ± 4.6 mm Hg in the impaired relaxation group and 24.7 ± 5.6 mm Hg in the restrictive group (p <0.001).

Discussion

In the present study changes in left atrial mechanics and, in particular, in the reservoir, pump and conduit function of the atrium, are detailed in response to different degrees of left ventricular filling impairment. Our data confirm that increased atrial booster pump function, in response to an impaired ventricular relaxation, is obtained at the expense of increased cavity volume5; they also point to the potential influence that increased atrial afterload (i.e., ventricular end-diastolic

References (22)

Cited by (0)

View full text