Atrial contribution to filling characteristics of the left ventricle in conscious dogs

Filling of the left ventricle (LV) consists of a ventri- cular and an atrial component. Diastasis refers to the equi- librium volume (Veq) which forms the transition between both components. We decided to study possible effects of pharma- cological adrenergic intervention on these filling charac- teristics by analyzing the relative contribution of both components. Accordingly, we analyzed left ventricular (LV) diameter (D) during rest (R), 20 ug/kg.min dobatamine (Do) and 3 ug/kg.min medetomidine (M) in dogs chronically instrumented with ultrasonic crystals in the equatorial plane of the LV. Total filling corresponds with enddiastolic diameter (EDD). ESD=endsystolic D. Atrial contribution (Vat) then equals EDD-Veq. Results are presented as pooled data of 10 second episodes for all dogs and all hemodynamic states yielding 91 data points. EDD = 3.05 + 0.964 Veq with r=0.998 ESD = 16.5 + 1.28 Veq with r=0.995 EDD = 43.6-5.43 Vat with r=0.419 Conclusion: Veq and EDD are linearly related in the con- scions dog during rest and both alpha and beta-adrenergic agonist intervention.