Assessment of Left Ventricular Viscoelastic Components Based on Ventricular Harmonic Behavior

Kheradvar, Arash; Milano, Michele; Gorman, Robert C.; Gorman, Joseph H.; Gharib, Morteza

doi:10.1007/s10558-006-9001-9

Cited by 11 publications

(12 citation statements)

References 34 publications

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“…The cardiac cycle commences at the initiation of systole (ntu = 0), and the vertical solid line (ntu = 0.4) divides systole from diastole. The negative signs for both functions indicate active force generation at the sarcomere level, as previously described by Kheradvar et al [21] and Mangual et al [20]. The plots follow an oscillatory pattern, indicating fluctuating changes in the viscoelasticity of the myocardial segments during contraction and relaxation.…”

Section: Resultssupporting

confidence: 73%

“…We have previously developed and validated a method to obtain dynamic viscoelastic information from the LV myocardium, based on considering LV as oscillating body with time-varying coefficients [20,21]:…”

Section: Methodsmentioning

confidence: 99%

“…The elastic component is associated with the time-varying elasticity of the myocardial segment, comparable to an oscillating spring with the ability to compress and stretch in the radial direction, and the viscous component is related to the time-varying compliance of the myocardial segment, or its resistance to recoil. This model has been previously validated in sheep [21]. The mechanical properties of three short-axis segments were computed for each volunteer as further discussed in the Appendix.…”

Section: Methodsmentioning

confidence: 99%

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Aging Does Not Affect Radial Viscoelastic Behavior of the Left Ventricle

et al. 2013

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Objectives: This study investigates the effect of aging on the radial viscoelastic behavior of the left ventricle (LV) based on a previously validated model that uses myocardial tissue phase mapping (TPM) of cine phase-contrast MRI. Methods: Previous studies suggest that aging remarkably influences regional myocardial motion, mostly myocardial velocities in both radial and long-axis directions. However, the effect of aging on cardiac viscoelasticity, which exhibits time-dependent strain, has not been elucidated yet. In this study, myocardial velocity and displacement mapping of the LV was performed using TPM in 39 healthy subjects divided into three age groups. The viscoelasticity parameters were obtained for each segment of the LV and compared among the studied groups. Results: The analyses showed that myocardial elasticity ranged from approximately 20 to -20 dyne/cm² during a cardiac cycle, and the myocardial viscous-damping component ranged from -1 to 1 dyne × s/cm². Overall, no statistically significant difference was observed in the viscoelasticity components among the subjects in the different age groups (p > 0.05). Conclusion: Myocardial viscoelastic behavior of the LV in radial direction was found to be considerably similar in pattern and magnitude among the studied subjects of different age groups with no statistically significant difference, despite the fact that the regional myocardial velocities change due to aging.

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Section: Resultssupporting

confidence: 73%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Aging Does Not Affect Radial Viscoelastic Behavior of the Left Ventricle

et al. 2013

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“…A measurement of myocardial stiffness can be obtained from the pressure-volume (P-V) relation. This value is most commonly measured by recording P-V loops across multiple heartbeats while gradually increasing blood pressure (Cingolani et al, 2003;Kheradvar et al, 2006;Mirsky et al, 1987). However, as a single value of stiffness is derived through multiple heartbeats, this method cannot provide measurements in specific regions of the heart, nor can it provide instantaneous measurements of stiffness.…”

Section: Introductionmentioning

confidence: 99%

In Vivo Assessment of Myocardial Stiffness with Acoustic Radiation Force Impulse Imaging

Hsu¹,

Bouchard²,

Dumont³

et al. 2007

Ultrasound in Medicine & Biology

112

106

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Acoustic radiation force impulse (ARFI) imaging has been demonstrated to be capable of visualizing variations in local stiffness within soft tissue. Recent advances in ARFI beam sequencing and parallel imaging have shortened acquisition times and lessened transducer heating to a point where ARFI acquisitions can be executed at high frame rates on commercially available diagnostic scanners. In vivo ARFI images were acquired with a linear array placed on an exposed canine heart. The electrocardiogram (ECG) was also recorded. When co-registered with the ECG, ARFI displacement images of the heart reflect the expected myocardial stiffness changes during the cardiac cycle. A radiofrequency ablation was performed on the epicardial surface of the left ventricular free wall, creating a small lesion that did not vary in stiffness during a heartbeat, though continued to move with the rest of the heart. ARFI images showed a hemispherical, stiffer region at the ablation site whose displacement magnitude and temporal variation through the cardiac cycle were less than the surrounding untreated myocardium. Sequences with radiation force pulse amplitudes set to zero were acquired to measure potential cardiac motion artifacts within the ARFI images. The results show promise for real-time cardiac ARFI imaging.

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“…This can be a result of inaccuracy in defining the onset of end-diastole due to ECG irregularities during surgery. Based on the present model, the mean damping coefficient can be considered zero in healthy hearts, denoting that the viscous damping is minimal in the normal LV [12]. Further study is in progress to observe the variations of coefficients in cases where the physical state of the LV has been changed due to the acquired or congenital heart diseases.…”

Section: Discussionmentioning

confidence: 90%

Estimation of elastic and viscous properties of the left ventricle based on annulus plane harmonic behavior

Kheradvar

Milano

Gorman

et al. 2006

2006 International Conference of the IEEE Engineering in Medicine and Biology Society

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Abstract-Assessment of left ventricular (LV) functionwith an emphasis on contractility has been a challenge in cardiac mechanics during the recent decades. The LV function is usually described by the LV pressurevolume (P-V) diagram. The standard P-V diagrams are easy to interpret but difficult to obtain and require invasive instrumentation for measuring the corresponding volume and pressure data. In the present study, we introduce a technique that can estimate the viscoelastic properties of the LV based on harmonic behavior of the ventricular chamber and it can be applied non-invasively as well. The estimation technique is based on modeling the actual long axis displacement of the mitral annulus plane toward the cardiac base as a linear damped oscillator with time-varying coefficients. The time-varying parameters of the model were estimated by a standard Recursive Linear Least Squares (RLLS) technique. LV stiffness at end-systole and end diastole was in the range of 61.86-136.00 dyne/g.cm and 1.25-21.02 dyne/g.cm, respectively. The only input used in this model was the long axis displacement of the annulus plane, which can also be obtained non-invasively using tissue Doppler or MR imaging.

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Assessment of Left Ventricular Viscoelastic Components Based on Ventricular Harmonic Behavior

Cited by 11 publications

References 34 publications

Aging Does Not Affect Radial Viscoelastic Behavior of the Left Ventricle

Aging Does Not Affect Radial Viscoelastic Behavior of the Left Ventricle

In Vivo Assessment of Myocardial Stiffness with Acoustic Radiation Force Impulse Imaging

Estimation of elastic and viscous properties of the left ventricle based on annulus plane harmonic behavior

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