Isovolumic acceleration measured by tissue Doppler echocardiography is preload independent in healthy subjects.
BACKGROUND
Isovolumic acceleration (IVA) as assessed by Tissue Doppler Imaging (TDI) has been proposed as a measure of left ventricular (LV) contractility. IVA is believed to be less dependent on preload than previously proposed estimates. IVA has been measured at different locations, and studies have shown conflicting results.


OBJECTIVE
We investigated the impact of increased preload on modern echocardiographic estimates of contractility, including IVA performed at different locations, in healthy volunteers.


METHODS
Seventeen young healthy individuals (male 13, age 31(+/- 9) years) with no prior history of cardiovascular or metabolic diseases had a Doppler and Tissue Doppler echocardiographic study performed at baseline and after a rapid infusion of 30 ml/kg of bodyweight of isotonic saline. Results are given as mean +/- standard deviation (SD), differences tested by paired t-test.


RESULTS
Echocardiographic parameters used to determine changes in preload, altered significantly. E/e' increased both at the lateral (5 +/- 1 vs 7 +/- 1 P < 0.01) and at the septal side of the annulus (7 +/- 2 vs 9 +/- 2, P < 0.01). Afterload remained unchanged. IVA was unchanged regardless of the measurement location: in the basal free wall (1.21 +/- 0.58 vs 0.98 +/- 0.41, not significant (NS)) or in the mitral annulus (1.18 +/- 0.56 vs 1.15 +/- 0.33, NS). Peak systolic strain, measured at the basal segment of LV septum, increased significantly (15.4 +/- 5.0 vs 20.7 +/- 5, P < 0.05), while all other measurements for strain or strain rate (SR) remained unchanged.


CONCLUSIONS
IVA is unchanged following significant increases in preload in healthy subjects, and thus is a potentially useful measure of global LV contractility.
Dalsgaard
Morten
M
Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark. Morten.Dalsgaard@rh.dk
Snyder
Eric M
EM
Kjaergaard
Jesper
J
Johnson
Bruce D
BD
Hassager
Christian
C
Oh
Jae K
JK
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001810:Blood Volume / Q000187:drug effects / Q000502:physiology*; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000187:drug effects; D006801:Humans; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D015588:Observer Variation; D012016:Reference Values; D012965:Sodium Chloride / Q000008:administration & dosage; D013318:Stroke Volume / Q000187:drug effects / Q000502:physiology; D016277:Ventricular Function, Left / Q000187:drug effects / Q000502:physiology*
D012965:Sodium Chloride