Ventricular untwisting: a temporal link between left ventricular relaxation and suction.
Left ventricular (LV) untwisting starts early during the isovolumic relaxation phase and proceeds throughout the early filling phase, releasing elastic energy stored by the preceding systolic deformation. Data relating untwisting, relaxation, and intraventricular pressure gradients (IVPG), which represent another manifestation of elastic recoil, are sparse. To understand the interaction between LV mechanics and inflow during early diastole, Doppler tissue images (DTI), catheter-derived pressures (apical and basal LV, left atrial, and aortic), and LV volume data were obtained at baseline, during varying pacing modes, and during dobutamine and esmolol infusion in seven closed-chest anesthetized dogs. LV torsion and torsional rate profiles were analyzed from DTI data sets (apical and basal short-axis images) with high temporal resolution (6.5 +/- 0.7 ms). Repeated-measures regression models showed moderately strong correlation of peak LV twisting with peak LV untwisting rate (r = 0.74), as well as correlations of peak LV untwisting rate with the time constant of LV pressure decay (tau, r = -0.66) and IVPG (r = 0.76, P < 0.0001 for all). In a multivariate analysis, peak LV untwisting rate was an independent predictor of tau and IVPG (P < 0.0001, for both). The start of LV untwisting coincided with the beginning of relaxation and preceded suction-aided filling resulting from elastic recoil. Untwisting rate may be a useful marker of diastolic function or even serve as a therapeutic target for improving diastolic function.
Notomi
Yuichi
Y
Department of Cardiovascular Medicine/F15, The Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH 44195, USA.
Popovic
Zoran B
ZB
Yamada
Hirotsugu
H
Wallick
Don W
DW
Martin
Maureen G
MG
Oryszak
Stephanie J
SJ
Shiota
Takahiro
T
Greenberg
Neil L
NL
Thomas
James D
JD
D000318:Adrenergic beta-Agonists / Q000008:administration & dosage; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage; D000818:Animals; D001794:Blood Pressure; D002304:Cardiac Pacing, Artificial; D003971:Diastole / Q000187:drug effects; D004280:Dobutamine / Q000008:administration & dosage; D004285:Dogs; D018618:Echocardiography, Doppler, Color; D004548:Elasticity; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D008955:Models, Cardiovascular; D009200:Myocardial Contraction / Q000187:drug effects; D011412:Propanolamines / Q000008:administration & dosage; D012107:Research Design; D013997:Time Factors; D054159:Torsion, Mechanical; D016277:Ventricular Function, Left / Q000187:drug effects; D017725:Ventricular Pressure
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D004280:Dobutamine; C036604:esmolol