Echocardiographic Assessment of Left Ventricular Twisting and Untwisting Rate in Normal Subjects by Tissue Doppler and Velocity Vector Imaging: Comparison of Two Methods

Changes in diastolic indexes during normal aging, including reduced early filling velocity ( E), lengthened E deceleration time (DT), augmented late filling ( A), and prolonged isovolumic relaxation time (IVRT), have been attributed to slower left ventricular (LV) pressure (LVP) decay. Indeed, this constellation of findings is often referred to as the “abnormal relaxation” pattern. However, LV filling is determined by the atrioventricular pressure gradient, which depends on both LVP decline and left atrial (LA) pressure (LAP). To assess the relative influence of LVP decline and LAP, we studied 122 normal subjects aged 21–92 yr by Doppler echocardiography and MRI. LVP decline was assessed by color M-mode ( Vp) and the LV untwisting rate. Early diastolic LAP was evaluated using pulmonary vein flow systolic fraction, pulmonary vein flow diastolic DT, color M-mode ( E/ Vp), and tissue Doppler ( E/ Em). Linear regression showed the expected reduction of E, increase in A, and prolongation of IVRT and DT with advancing age. There was no relation of age to parameters reflecting the rate of LVP decline. However, older age was associated with reduced E/ Vp ( P = 0.008) and increased pulmonary vein systolic fraction ( P < 0.001), pulmonary vein DT ( P = 0.0026), and E/ Em ( P < 0.0001), all suggesting reduced early LAP. Therefore, reduced early filling in older adults may be more closely related to a reduced early diastolic LAP than to slower LVP decline. This effect also explains the prolonged IVRT. We postulate that changes in LA active or passive properties may contribute to development of the abnormal relaxation pattern during the aging process.

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INTRA-LEFT VENTRICULAR FLOW DISTRIBUTIONS IN DIASTOLIC AND SYSTOLIC PHASES, BASED ON ECHO VELOCITY FLOW MAPPING OF NORMAL SUBJECTS AND HEART FAILURE PATIENTS, TO CHARACTERIZE LEFT VENTRICULAR PERFORMANCE OUTCOMES OF HEART FAILURE

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519412400295 ◽

2012 ◽

Vol 12 (05) ◽

pp. 1240029 ◽

Cited By ~ 2

Author(s):

THU-THAO LE ◽

RU-SAN TAN ◽

FEIQIONG HUANG ◽

LIANG ZHONG ◽

SRIDHAR IDAPALAPATI ◽

...

Keyword(s):

Heart Failure ◽

Velocity Vector ◽

Normal Subjects ◽

Performance Outcomes ◽

Left Ventricular ◽

Inflow Rate ◽

Flow Mapping ◽

Velocity Flow ◽

Outflow Rate ◽

Blood Flow Patterns

Heart failure (HF), one of the most common diseases in the world, causes left ventricular dysfunction (LV) and high mortality. HF patients are stratified into two groups based on their LV ejection fraction (EF) — HF with normal EF (HFNEF) and with reduced EF (HFREF). EF is a commonly used measure of LV contractile performance. Despite preserved EF, a complex mixture of systolic and diastolic dysfunction and variable degrees of LV remodelling underlying HFNEF poses challenges to diagnose and provide pharmacological treatment for HFNEF. In recent years, the velocity flow mapping (VFM) technique has been developed to generate flow velocity vector fields by post-processing color Doppler echocardiographic (echo) images. We aim to obtain the intra-LV blood flow patterns for patients with HFNEF, HFREF, and normal subjects, in order to characterize the LV performance outcomes of normal subjects and HF patients. Two subjects from each group of HFNEF, HFREF, and normal underwent echo scans. Velocity vector distributions throughout the cardiac cycle were then analysed using the VFM technique. In each subject, the outflow rate during systole, inflow rate during diastole, as well as wall stress-based pressure-normalized contractility index, dσ*/dt max , were computed and compared among the groups. This study demonstrated the use of VFM to visualize LV blood flow patterns in HF patients and normal subjects. Different patterns of flow distributions were observed in these subjects. In HFREF patients, dσ*/dt max , the peak outflow rate and peak inflow rate during early filling were markedly reduced. In HFNEF patients, peak outflow rates were increased compared to those of normal subjects.

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