Left atrial Frank-Starling law assessed by real-time, three-dimensional echocardiographic left atrial volume changes.
BACKGROUND
The Frank-Starling law describes the relation between left ventricular volume and function. However, only a few studies have described the relation between left atrial volume (LAV) and function.


OBJECTIVE
To describe an LA Frank-Starling law by studying changes in LAV measured by real-time, three-dimensional echocardiography (RT3DE).


METHODS
LAV was calculated by RT3DE in 70 patients at end-systole (LAV(max)), end-diastole (LAV(min)) and pre-atrial contraction (LAV(pre-A)). According to LAV(max), patients were classified into three groups: LAV(max) <50 ml (group I), LAV(max) 50-70 ml (group II) and LAV(max) >70 ml (group III). Calculated indices of LA pump function were active atrial stroke volume (SV), defined as LAV(pre-A) - LAV(min), and active atrial emptying fraction (EF), defined as active atrial SV/LAV(pre-A) x100%


RESULTS
Active atrial SV was significantly higher in group II than in group I (mean (SD) 19.0 (9.2) vs 8.2 (4.9) ml, p<0.0001), in group III it was non-significantly lower than in group II (16.7 (12.5) vs 19.0 (9.2) ml). Active atrial SV correlated well with LAV(pre-A) (r = 0.56, p<0.001), but decreased with larger LAV(pre-A). Active atrial EF tended to be higher in group II than in group I (43.1 (18.2) vs 33.2 (17.5), p<0.10), in group III it was significantly lower than in group II (26.2 (18.5) vs 43.1 (18.2), p<0.01).


CONCLUSIONS
A Frank-Starling mechanism in the left atrium could be described by RT3DE, shown by an increase in LA contractility in response to an increase in LA preload up to a point, beyond which LA contractility decreased.
Anwar
Ashraf M
AM
Cardiology Department, Al-Husein University Hospital, Al-Azhar University, Cairo, Egypt.
Geleijnse
Marcel L
ML
Soliman
Osama I I
OI
Nemes
Attila
A
ten Cate
Folkert J
FJ
D000328:Adult; D016275:Atrial Function / Q000502:physiology; D019560:Echocardiography, Three-Dimensional; D005260:Female; D006321:Heart / Q000033:anatomy & histology*; D006325:Heart Atria / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D009200:Myocardial Contraction / Q000502:physiology; D015588:Observer Variation; D013318:Stroke Volume / Q000502:physiology