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Biomedical subjects

Boaz D Rosen

Publications and source records attributed to Boaz D Rosen.

12 recordsLinked to original sources
PubMed2007

Elevated homocysteine is associated with reduced regional left ventricular function: the Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: An elevated homocysteine (Hcy) level has been reported to be a risk factor for the development of congestive heart failure in individuals free of myocardial infarction. In this study, we aim to investigate the relationship between Hcy levels and regional left ventricular function in an asymptomatic population. METHOD AND RESULTS: Regional peak systolic midwall circumferential strains were calculated from 1178 tagged magnetic resonance imaging studies in participants in the Multi-Ethnic Study of Atherosclerosis (MESA). Left ventricular regions were defined by coronary territories (left anterior descending, left circumflex, right coronary artery). For the 1178 study participants (66+/-10 years of age, 58% males), the median (interquartile range) of Hcy was 9.1 (9.0 to 9.3). After adjustment for traditional risk factors, race, height, weight, left ventricular end-diastolic mass/volume, serum creatinine, and measures of atherosclerosis, reduced regional myocardial circumferential shortening across sex-specific quartiles of plasma Hcy in the left anterior descending (P=0.038) and left circumflex (P=0.009) regions persisted, which indicated an important association of reduced function with elevated Hcy. Multiple linear regression analyses confirmed that circumferential systolic dysfunction was associated with log transformed Hcy levels in the left anterior descending (P=0.004) and left circumflex (P=0.0002) regions. In the fully adjusted model, the odds ratio for left ventricular strains below the 10th percentile with 1 SD increases in log-transformed Hcy was 1.33 (95% confidence interval, 1.04 to 1.70; P=0.022) for the left anterior descending, 1.28 (95% confidence interval, 1.00 to 1.64; P=0.046) for the left circumflex, and 1.32 (95% confidence interval, 1.03 to 1.69; P=0.025) for the right coronary artery region. CONCLUSIONS: In this asymptomatic population, an elevated Hcy level is associated with reduced regional left ventricular systolic function detected by tagged magnetic resonance imaging.

Aged↗
PubMed2006

Lower myocardial perfusion reserve is associated with decreased regional left ventricular function in asymptomatic participants of the multi-ethnic study of atherosclerosis.

BACKGROUND: Myocardial ischemia is an important determinant of regional left ventricular systolic function. Myocardial blood flow reserve may be impaired by cardiovascular disease before alterations of myocardial perfusion at rest become manifest. Nevertheless, the relation between flow reserve and regional myocardial function has not been studied in individuals without a history of clinical heart disease. METHODS AND RESULTS: Seventy-four participants (66+/-9 years, mean+/-SD) of the Multi-Ethnic Study of Atherosclerosis (MESA) underwent myocardial magnetic resonance tagging and contrast-enhanced perfusion studies. Regional myocardial function was evaluated as peak systolic circumferential strain (Ecc) in the three main coronary territories (left anterior descending [LAD], left circumflex, and right coronary artery [RCA]). Myocardial blood flow at rest and during adenosine-induced hyperemia was quantified by contrast-enhanced magnetic resonance imaging, to study the relation between regional flow and function after multivariable adjustment for age, gender, body mass index, left ventricular mass, and traditional risk factors. Lower regional myocardial blood flow during hyperemia was associated with reduced regional left ventricular function expressed as lower Ecc in the RCA (P<0.01) and left circumflex regions (P<0.05) measured in the subendocardium, mid-wall, and subepicardium. In contrast, no significant association was seen in the LAD territory (P=0.16). In addition, segmental function in LAD and RCA regions was reduced when individuals in the lowest 10th percentile for regional myocardial flow reserve were compared with the other participants. Absolute decreases in mid-wall Ecc LAD and RCA and global Ecc were 3.0%, 3.4%, and 2.8%, respectively (P<0.05 for all regions). CONCLUSIONS: Lower myocardial flow reserve is related to reduced regional function in asymptomatic individuals.

Aged↗
PubMed2006

Hypertension and smoking are associated with reduced regional left ventricular function in asymptomatic: individuals the Multi-Ethnic Study of Atherosclerosis.

OBJECTIVES: This study sought to test the hypothesis that reduced regional left ventricular (LV) function is associated with traditional risk factors including hypertension, hypercholesterolemia, and smoking in asymptomatic individuals. BACKGROUND: Coronary artery disease is the main etiology of congestive heart failure in the U.S. and Europe. However, the relationship between risk factors for coronary artery disease and decreased myocardial function has not been studied systematically in asymptomatic individuals. METHODS: The Multi-Ethnic Study of Atherosclerosis (MESA) is a cohort study designed to investigate the nature of atherosclerosis in asymptomatic individuals. A total of 1,184 participants (45 to 84 years old) underwent tagged cardiac magnetic resonance imaging. Regional LV function was quantified by analyzing peak systolic circumferential strain (Ecc) in regions corresponding to the left anterior descending (LAD), circumflex (LCX), and right coronary (RCA) territories. The association between risk factors and strains was studied using multiple linear regression. RESULTS: Higher diastolic blood pressure (DBP) was associated with lower Ecc (p < or = 0.002). The Ecc's in the LAD territory of participants with DBP <80, 80 to 84, 85 to 89, and > or =90 mm Hg were -15.6%, -14.8%, -14.2%, and -13.7%, respectively (p < 0.001). Similar results were documented in other territories and after multivariable analysis. Smokers had lower Ecc in the LAD and RCA regions compared with nonsmokers. Furthermore, dose response relationship between cigarette consumption measured in pack-years and regional LV dysfunction by Ecc was noted (p < or = 0.01 in LAD and RCA territories). Finally, combined diastolic hypertension and smoking was associated with a greater reduction of regional LV function. CONCLUSIONS: Higher diastolic blood pressure and smoking are associated with decreased regional LV function in asymptomatic individuals.

Aged↗
PubMed2006

Imaging of myocardial dyssynchrony in congestive heart failure.

Heart failure constitutes a major health problem in USA and Europe. Angiotensin converting enzyme inhibitors and _ blockers were shown to reduce morbidity and mortality in patients with CHF. Yet, their effectiveness is limited. A significant number of patients with heart failure manifest myocardial conduction abnormalities. Conduction abnormalities, especially in the form of left bundle branch block (LBBB) may be associated with abnormal mechanical function. Several studies demonstrated that these patients may gain benefit from biventricular (BiV) pacing in terms of improvement in exercise tolerance, heart failure morbidity and even decreased mortality. BiV pacing was also associated with improvement in ejection fraction, reduction in the extent of mitral regurgitation and a decrease in cardiac size (reverse remodeling). However, a significant number of patients do not gain benefit from biventricular pacing despite having conduction abnormalities. The underlying reason is that the electrical activity may not closely reflect mechanical activity. Several imaging modalities and techniques have been proposed to improve the selection of patients who may benefit from biventricular pacemakers. Of those, echo-Doppler, and especially, Tissue Doppler Imaging has been demonstrated as important tools for evaluating patients for cardiac resynchronization therapy (CRT) and following their response. The advantages of echo include accessibility, portability, its cost and a high temporal resolution. Yet, it is limited by its acoustic windows and scanning angles. MRI is a useful tool for evaluating patients for CRT by providing 3-D image of myocardial function. However, it is limited for follow-up after implantation due to its cost and a potential damage to the patients or pacemakers. Dyssnchrony imaging is a rapidly evolving field. New imaging techniques such as speckle tracking are promising and close update is needed to keep track of the developments and the changes in this exciting field.

Bundle-Branch Block↗
PubMed2006

Regional diastolic dysfunction in individuals with left ventricular hypertrophy measured by tagged magnetic resonance imaging--the Multi-Ethnic Study of Atherosclerosis (MESA).

BACKGROUND: Impairment of global diastolic function is considered to be the mechanism of congestive heart failure in individuals with preserved systolic left ventricular (LV) function. Left ventricular hypertrophy (LVH) is known to be a risk factor for congestive heart failure with preserved systolic function, and this process may begin as a regional process. We investigated whether regional LV diastolic function measured by magnetic resonance tagging is altered in asymptomatic participants of the MESA with LVH and preserved systolic LV function. METHODS: Regional systolic and diastolic strain rates were calculated from strain data in 218 participants of the MESA study. Circumferential strain was calculated from the midwall layer of the septum, anterior, lateral, and inferior walls at mid-LV level. Global LV function measures were studied by magnetic resonance imaging in 4291 MESA participants. Left ventricular hypertrophy for men and women was defined from the MESA population using previously established Framingham criteria. RESULTS: Global systolic function was slightly less in the LVH (ejection fraction = 0.66 +/- 0.10) versus the non-LVH group (ejection fraction = 0.69 +/- 0.07, P < .001). Stepwise regression analyses showed a direct relationship between regional diastolic dysfunction and increasing LV mass. Regional systolic strain and strain rate measures from participants with LVH were not significantly different from those without LVH. However, regional diastolic strain rate was significantly reduced in participants with LVH (1.5 +/- 1.1 s(-1)) compared with the non-LVH group (2.2 +/- 1.1 s(-1), P < .001) regardless of age or sex. CONCLUSIONS: Left ventricular hypertrophy is associated with regional diastolic dysfunction in individuals without evidence of clinical cardiovascular disease and preserved systolic function. Magnetic resonance imaging tagging provides detailed quantification of regional diastolic function noninvasively.

Aged↗
PubMed2005

New noninvasive method for assessment of left ventricular rotation: speckle tracking echocardiography.

BACKGROUND: Left ventricular (LV) torsion is due to oppositely directed apical and basal rotation and has been proposed as a sensitive marker of LV function. In the present study, we introduce and validate speckle tracking echocardiography (STE) as a method for assessment of LV rotation and torsion. METHODS AND RESULTS: Apical and basal rotation by STE was measured from short-axis images by automatic frame-to-frame tracking of gray-scale speckle patterns. Rotation was calculated as the average angular displacement of 9 regions relative to the center of a best-fit circle through the same regions. As reference methods we used sonomicrometry in anesthetized dogs during baseline, dobutamine infusion, and apical ischemia, and magnetic resonance imaging (MRI) tagging in healthy humans. In dogs, the mean peak apical rotation was -3.7+/-1.2 degrees (+/-SD) and -4.1+/-1.2 degrees, and basal rotation was 1.9+/-1.5 degrees and 2.0+/-1.2 degrees by sonomicrometry and STE, respectively. Rotations by both methods increased (P<0.001) during dobutamine infusion. Apical rotation by both methods decreased during left anterior descending coronary artery occlusion (P<0.007), whereas basal rotation was unchanged. In healthy humans, apical rotation was -11.6+/-3.8 degrees and -10.9+/-3.3 degrees, and basal rotation was 4.8+/-1.7 degrees and 4.6+/-1.3 degrees by MRI tagging and STE, respectively. Torsion measurement by STE showed good correlation and agreement with sonomicrometry (r=0.94, P<0.001) and MRI (r=0.85, P<0.001). CONCLUSIONS: The present study demonstrates that regional LV rotation and torsion can be measured accurately by STE, suggesting a new echocardiographic approach for quantification of LV systolic function.

Animals↗
PubMed2005

Coronary artery atherosclerosis is related to reduced regional left ventricular function in individuals without history of clinical cardiovascular disease: the Multiethnic Study of Atherosclerosis.

OBJECTIVE: We investigated whether regional coronary calcium score by computed tomography is related to regional left ventricular systolic function measured by MRI tagging in participants of the Multiethnic Study of Atherosclerosis. METHODS AND RESULTS: The Multiethnic Study of Atherosclerosis is a prospective observational study of men and women without a history of previous heart disease from 4 ethnic groups. Calcium scores were measured separately for the left anterior descendent (LAD), left circumflex (LCX), and right (RCA) coronary arteries. Left ventricular strain and strain rate were determined by tagged MRI in the corresponding vascular territories of the coronary vessels in 509 participants. Greater coronary calcification in the LAD, LCX, and right RCA coronary arteries were related to worse function in their respective perfusion. Anterior wall strain rate was -1.37+/-0.41 when LAD calcium was zero versus -1.17+/-0.24 1/s in the highest quartile of calcium score (P<0.001). Similar relationships were evident in the LCX and RCA regions. Participants with 1- and 2-vessel coronary artery calcium had better myocardial function in the remote area compared with the territory supplied by the diseased artery. CONCLUSIONS: High-local calcium score is related to regional dysfunction in the corresponding coronary territory among individuals without a history of previous heart disease. These results indicate a link between atherosclerosis and subclinical regional left ventricular dysfunction.

Black or African American↗
PubMed2005

Left ventricular concentric remodeling is associated with decreased global and regional systolic function: the Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: The transition from compensatory concentric remodeling to myocardial failure is not completely understood in humans. To investigate determinants of incipient myocardial dysfunction, we examined the association between concentric remodeling and regional LV function in asymptomatic participants of the Multi-Ethnic Study of Atherosclerosis (MESA). METHODS AND RESULTS: Myocardial tagged MRI was performed. Regional myocardial function expressed as peak systolic midwall circumferential strain (Ecc) was analyzed in 441 consecutive studies by HARP (Harmonic Phase) tool. Peak Ecc was correlated with the extent of concentric remodeling determined by the ratio of left ventricular mass to end-diastolic volume (M/V ratio). In men, a gradual decline in peak global Ecc was seen with increasing M/V ratio (test for trend, P<0.001). Among women, however, Ecc tended to be lower only in the fifth compared with the first quintile of M/V ratio (P=0.1). The association of lower Ecc with increasing M/V ratio was regionally heterogeneous but was particularly prominent in the LAD region in men (test for trend, P<0.001) and in women (test for trend, P=0.02). In the right coronary and left circumflex artery territories, these associations were less marked in both genders. CONCLUSIONS: In this cross-sectional study of asymptomatic individuals, concentric left ventricular remodeling was related to decreased regional systolic function. The reduction in regional function, which was more pronounced in the left anterior descending coronary artery territory, may reflect the local transition from compensatory remodeling to myocardial dysfunction.

Atherosclerosis↗
PubMed2005

Quantitative assessment of regional myocardial function with MR-tagging in a multi-center study: interobserver and intraobserver agreement of fast strain analysis with Harmonic Phase (HARP) MRI.

PURPOSE: To assess the reproducibility of Harmonic Phase (HARP) analysis of myocardial MR tagged images acquired in the Multi-Center Study of Atherosclerosis (MESA). METHODS: Using the HARP method, three independent observers performed two separate quantitative strain analyses of myocardial cine MR-tagging images blindly in 24 participants. The images were obtained in four different centers and analyzed at a single core lab. Each study comprised 3 short-axis slices subdivided in 12 segments (24 x 3 x 12 = 864 segments), each with three layers. Normal strains (circumferential [Ecc] and radial [Err]), principal strains (Lambda1, Lambda2), and the angle alpha (between Ecc-Lambda2) were calculated. Intraclass correlation coefficient (R) for peak systolic strains, and all pooled systolic and diastolic strain data were used to determine inter- and intraobserver agreement. Two observers also visually graded study quality. R values were related to the image quality in different myocardial regions and layers. RESULTS: Overall, HARP yielded an excellent inter- and intraobserver agreement for peak systolic strain data (for Ecc, R = 0.84 and 0.89, respectively) and all systolic pooled data (for Ecc, interobserver R = 0.82, intraobserver R = 0.69-0.76). Both inter and intraobserver agreement were lower for diastolic pooled data (R = 0.69 and 0.58-0.62, respectively). There was a direct relationship between image quality and performance of the HARP analysis, with increasing inter- and intraobserver R values in studies with longer tag persistence. Both inter- and intraobserver agreement were better in the anterior and septal myocardial regions, and in the midwall layer. The intraobserver agreement was similar among the three observers. CONCLUSION: Employing the HARP method for quantitative strain analysis of myocardial MR tagged images provides a high inter- and intraobserver agreement. These good results are obtained in case of good to excellent MR image quality.

Aged↗
PubMed2004

Late systolic onset of regional LV relaxation demonstrated in three-dimensional space by MRI tissue tagging.

Left ventricular (LV) relaxation entails myocardial deformation that induces LV filling. Yet, the precise mechanisms of the earliest changes in tissue properties that characterize myocardial relaxation remain incompletely understood. Ten healthy volunteers (seven males), 25-43 yr, underwent tagged and cine MRI with high temporal resolution (25-35 ms). Normal strains including radial (E(rr)), circumferential (E(cc)), and longitudinal (E(ll)) strains, shear strains including E(cl) (circumferential-longitudinal), E(cr) (circumferential-radial), and E(rl) (radial-longitudinal), and principal strains (E(1), E(2), and E(3)) were calculated using a displacement field-fitting method. Temporal changes in angular strains indicative of shear and torsion release and normal strains were studied during late systole and early relaxation. The onset of individual relaxation strains was heterogeneous relative to LV filling. Shear strains (E(cr), E(rl), and E(cl)) and radial thinning were first to develop. Times of onset of E(cr), E(rl), E(cl), and E(rr) occurred 108, 93, 67, and 73 ms before aortic valve closure, respectively. E(ll), E(cc), and LV volume change commenced significantly later after the onset of diastolic shear strains and radial thinning. The onset of E(cc), E(ll), and LV volume change was noted 38 ms before aortic valve closure (P < or = 0.05 relative to the onset of shear strains and E(rr)). Myocardial relaxation is characterized by a three-dimensional unfolding deformation that includes release of torsion, shear, and radial thinning beginning before aortic valve closure. This unfolding pattern precedes longitudinal and circumferential elongation and may facilitate early diastolic filling.

Adult↗