English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

To characterize the pump function of the left atrium, we determined the instantaneous pressure-volume relation of the isolated supported left atrium. A physiologic after-loading system for the low-pressure atrium was created by coupling it to a real-time computer-simulated ventricle and a simulated venous impedance network via a volume servo-pump. In 10 atria loaded with such systems, multiple isochronal sets of pressure-volume data were collected from many ejecting or isovolumic contractions obtained under a constant inotropic state, and the time-varying elastance, E(t), as well as the volume-axis intercepts, VO(t), were calculated. E(t) is the ensemble of slopes, and VO(t), the volume-axis intercepts resulting from the linear regression of instantaneous pressure on instantaneous volume at multiple instants throughout the cardiac cycle. The systolic portion of the left atrial E(t) was insensitive to loading conditions, as was VO(t), which, in addition, proved to be similar to the right atrial and right ventricular VO(t) waveforms in its time dependence. These results indicate that E(t) and VO(t) adequately represent the instantaneous pressure-volume relation of the left atrium in systole irrespective of the mode of contraction. Whatever the underlying mechanism might be, the load insensitivity and similarity of the basic shape of the left atrial E(t) among different atria suggests that the characterization reflects fundamental features of left atrial contraction.

Instantaneous pressure-volume relation of the ejecting canine left atrium.