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Bijoy Khandheria

Publications and source records attributed to Bijoy Khandheria.

8 recordsLinked to original sources

Two-dimensional acoustic pattern derived strain parameters closely correlate with one-dimensional tissue Doppler derived strain measurements.

BACKGROUND: Two-dimensional strain echocardiography (2D-SE) calculates tissue velocities via frame-to-frame tracking of unique acoustic markers within the image and provides strain parameters in two dimensions. Novel 2D-SE software allows semi-automated strain measurements and increased averaging capabilities optimizing signal-noise ratio. AIM: We tested whether 2D-SE and the currently used and well-validated tissue Doppler derived strain echocardiography (TD-SE) yield similar information in the clinical setting. METHODS AND RESULTS: We performed 2D-SE and TD-SE on 17 patients with amyloid cardiomyopathy and 10 age-matched healthy volunteers. Single walls from standard apical views (2- and 4-chamber) were acquired at high frame rates ( approximately 200fps). Offline analysis was performed by observers blinded to clinical data using the EchoPAC program with custom 2D-SE software. Longitudinal strain rate and strain from the basal, mid and apical segments of the septal and lateral walls were determined by each method (TD-SE and 2D-SE). Ejection fraction was >0.55 in healthy volunteers and ranged from 0.30 to 0.80 in cardiomyopathy group. A total of 54 walls (162 segments) were examined. Acceptable quality strain data was available in 92% and 85% segments by 2D-SE and TD-SE, respectively. Two-dimensional strain echocardiography values correlated closely with TD-SE values (r=0.94 and 0.96 for strain rate and strain, respectively). CONCLUSIONS: Deformation analysis by 2D-SE is feasible in a clinical setting and 2D-SE values correlate closely with TD-SE measurements over a wide range of global systolic function. Two-dimensional strain echocardiography may help to facilitate the routine clinical implementation of deformation analysis.

Acoustics↗

Analysis of the interaction between segmental relaxation patterns and global diastolic function by strain echocardiography.

BACKGROUND: Strain echocardiography can depict segmental mechanical activity with high temporal and spatial accuracy, and may allow assessment of segmental relaxation not possible with conventional echocardiography. METHODS: Conventional and strain echocardiography were performed in healthy volunteers (young [group 1] and old [group 2]) and patients with normal 2-dimensional and stress echocardiography, with either normal global diastolic function (group 3a) or grade I or II global diastolic dysfunction (DD) (group 3b). Standard echocardiography criteria were used to define global DD. Early to late diastolic strain rate ratio less than 1.1 was defined as altered segmental relaxation. RESULTS: All participants had normal wall motion and ejection fraction. Participants of group 1 had normal segmental and global diastolic function. Participants of groups 2 and 3a demonstrated a wide range of altered segmental relaxation in the absence of global DD. All patients of group 3b had 12 or more segments with altered relaxation and global DD. Age and hypertension were associated with a larger number of altered segments, a lower mean early to late diastolic strain rate ratio, and global DD. CONCLUSIONS: A wide range of altered segmental relaxation can exist in the absence of global DD. Age and hypertension are associated with altered segmental relaxation and global DD. Assessment of segmental relaxation may be beneficial in the elderly and patients with hypertension.

Adult↗

Strain echocardiography tracks dobutamine-induced decrease in regional myocardial perfusion in nonocclusive coronary stenosis.

OBJECTIVES: This study was designed to determine whether strain echocardiography parameters reflect changes in regional myocardial perfusion during dobutamine stress. BACKGROUND: Strain echocardiography depicts regional myocardial mechanical activity. Ischemia has been shown to reduce systolic strain rate (sSR) and prolong the time to regional lengthening (T(RL)). In an experimental model, we tested whether sSR and T(RL) tracked dobutamine-induced changes in regional myocardial perfusion (regional myocardial blood flow [RMBF]), as measured by colored microspheres. METHODS: We used a closed-chest pig model of nonocclusive coronary stenosis (n = 14) created by inflating an angioplasty balloon in the proximal left anterior descending artery. Invasive hemodynamics, RMBF, and strain parameters were measured at baseline and peak dobutamine stimulation before and during the coronary stenosis. We compared segments with reduced RMBF versus those with preserved RMBF at peak dobutamine stimulation. RESULTS: Peak sSR correlated with RMBF (r = 0.70). In the absence of coronary stenosis, dobutamine stimulation caused a significant increase in RMBF and sSR and a decrease in T(RL). This response was blunted during coronary stenosis. Using the "best cutoff" method, the sensitivity and specificity for prediction of reduced RMBF (ischemia) was 81% and 91% for sSR and 65% and 91% for T(RL), respectively. These changes occurred in the absence of any change in global systolic and diastolic function (dP/dT(max), dP/dT(min), and tau). CONCLUSIONS: Novel strain parameters that depict regional myocardial mechanics are able to predict changes in RMBF during dobutamine stress. Quantitative strain parameters may complement current echocardiographic techniques for ischemia detection and potentially improve the accuracy and reproducibility of stress echocardiography.

Animals↗

Early morning attenuation of endothelial function in healthy humans.

BACKGROUND: Cardiovascular events such as myocardial infarction, sudden death, and stroke have a peak incidence in the early hours after waking. The mechanisms involved in this circadian variation are not clear. Endothelial dysfunction is associated with increased risk for cardiovascular events. We tested the hypothesis that endothelial function is reduced in the early morning, around the time of waking, compared with measurements obtained both before sleep and later in the day in healthy humans. METHODS AND RESULTS: We studied 30 subjects (19 men, 11 women; mean age, 41.6 years). All participants underwent polysomnography to exclude obstructive sleep apnea or other sleep disorders. Brachial artery flow-mediated endothelium-dependent vasodilation (FMD) and endothelium-independent dilation (non-FMD) were measured on 3 different occasions: before subjects went to sleep (9 PM), the next morning immediately after waking (6 AM), and during the late morning 5 hours after waking (11 AM). All subjects had normal sleep with good sleep efficiency of 84+/-2%. Compared with before sleep, FMD decreased markedly in the early morning after waking and recovered by late morning (9 pm, 7.5+/-1%; 6 am, 4.4+/-0.7%; 11 am, 7.7+/-1%; P=0.02). Non-FMD was similar for the 3 periods of observation (9 pm, 17.3+/-1.6%; 6 am, 17.2+/-1.3%; 11 am, 18.5+/-1.7%). CONCLUSIONS: FMD is blunted in the early morning in healthy subjects. Decreased endothelial function in the early morning may have implications for our understanding of the morning peak in cardiac and vascular events.

Adult↗

Time to onset of regional relaxation: feasibility, variability and utility of a novel index of regional myocardial function by strain rate imaging.

OBJECTIVES: Time to onset of regional relaxation (T(R)) has been proposed as a novel index of regional myocardial function. This study sought to prospectively establish the feasibility and variability of T(R) in healthy volunteers (CONTROL) and to examine its utility in patients with inducible ischemia (PATIENT). BACKGROUND: Strain rate imaging (SRI) depicts myocardial deformation and enables quantitation of regional myocardial function with high temporal and spatial resolution. Thus, regional mechanical events can be accurately timed with SRI. The time point of regional transition from contraction to relaxation is altered in pathologic states. METHODS: Resting mean segmental T(R) was determined in 60 subjects: 20 in the CONTROL group and 40 in the PATIENT group. T(R) was also measured at peak dobutamine stress in the PATIENT group. An automated image analysis program determined the time point of transition from regional contraction to relaxation activity, and calculated T(R), defined as the time, in milliseconds, from the electrocardiogram R-wave to this transition point. RESULTS: Automated T(R) measurements were feasible in more than 90% of the segments in CONTROL and PATIENT groups. Mean T(R) was 353 +/- 24 ms and was shorter in the mid segments compared to apical and basal segments. Intra- and interobserver variability were low (6% and 9%, respectively). In the PATIENT group, the percent decrease in T(R) during dobutamine stress was significantly higher in normal compared to ischemic segments (30% vs. 19%, respectively, p = 0.01). A percent change >20% in T(R) identified patients with an ischemic response during dobutamine infusion (sensitivity 92%, specificity 75%). CONCLUSIONS: T(R), a novel quantitative index of regional myocardial function, can be determined with low variability and satisfactory feasibility in routine clinical settings. Percent change in T(R) identifies ischemic segments during dobutamine stress echocardiography (DSE) and may allow quantitative assessment of DSE.

Adult↗