Obesity and Right Ventricular Structure and Function

Abstract

T he prevalence of obesity has doubled in adults and more than tripled in children in the United States in the past 25 years and increases the risk of heart failure and death. 1,2 Obesity is associated with increases in total blood volume, left ventricular (LV) mass, LV stroke volume, and cardiac output without changes in LV ejection fraction (LVEF). 3-7 Also seen is the direct infi ltration or metaplasia of fat in the heart, termed the "cardiomyopathy of obesity." [8][9][10] Right ventricular (RV) morphology and function are important determinants of outcome in cardiopulmonary conditions, such as COPD, congestive heart failure, and pulmonary arterial hypertension. [11][12][13] Although obesity clearly affects the LV, few studies have examined the impact of obesity on the RV. Studies have shown RV systolic and diastolic dysfunction in overweight and obese individuals. 14,15 However, these were small studies of selected populations without signifi cant ethnic diversity using transthoracic echocardiography, which has limitations in the evaluation of the RV particularly in obese individuals. MRI offers precise and reproducible assessment of the RV and is considered the standard of reference for determination of RV morphology. 16 The aim of this study was to assess the relationship between obesity and RV structure and function assessed with MRI in a multiethnic population free of clinical cardiovascular disease. Background:The relationship between obesity and right ventricular (RV) morphology is not well studied. We aimed to determine the association between obesity and RV structure and function in a large multiethnic population-based cohort. Results: The study sample included 4,127 participants. After adjustment for demographics, height, education, and cardiovascular risk factors, overweight and obese participants had greater RV mass (6% and 9% greater, respectively), larger RV end-diastolic volume (8% and 18% greater, respectively), larger RV stroke volume (7% and 16% greater, respectively), and lower RV ejection fraction ( Ն 1% lower) than lean participants (all P , .001). These fi ndings persisted after adjusting for the respective left ventricular (LV) parameters. Conclusions: Overweight and obesity were independently associated with differences in RV morphology even after adjustment for the respective LV measure. This association could be explained by increased RV afterload, increased blood volume, hormonal effects, or direct obesity-related myocardial effects.CHEST 2012; 141(2):388-395

Increased Cardiovascular Stiffness and Impaired Age-related Functional Status

“…The resting CV stiffness and mobility scores identified in the participants in this study are similar to those reported previously in other populations of elderly individuals (44,45). With regard to cardiac metrics, women exhibited a higher LV ejection fraction (p < .001) and CV stiffness (p = .01).…”

“…Several demographic features of the study participants including body mass index, medical history, and CV medication use were similar to those found in other studies evaluating middle-aged and older adults both at risk for or with a diagnosis of compensated CHF (5,(44)(45)(46)(47)(48). There were, however, some differences in our population of 445 individuals relative to these other previously studied populations.…”

Right Ventricular Volumes and Systolic Function by Cardiac Magnetic Resonance and the Impact of Sex, Age, and Obesity in a Longitudinally Followed Cohort Free of Pulmonary and Cardiovascular Disease

“…Although MESA investigators adjusted for ethnicity, it is notable that the proportion of Chinese (with greater RV EF) decreased over increasing BMI category, whereas the proportion of blacks (with lower RV EF) increased with BMI category. 14 There are prior reports of RV reference values determined using SSFP CMR. Maceira et al scanned 120 healthy adults (60 men; 20-80 years; 10 subjects/age decade) 6 and found greater absolute and greater indexed RV volumes and mass in men, but no sex differences in EF.…”

New Cardiac Magnetic Resonance Reference Ranges for Right Ventricular Volumes and Systolic Function

“…The authors reported increased RVEF with advancing age, increased RV end-diastolic volume but lower RVEF in men versus women, lower RVEF in black versus white individuals as well as higher right ventricular enddiastolic volume and lower RVEF in obese individuals. 8,9 Several other studies 7,10 have provided normal reference ranges for RV volumes and systolic function using contemporaneous SSFP acquisition, but these are on a much smaller scale than the study by Foppa et al 11 in this issue of Circulation: Cardiovascular Imaging.…”

“…The authors reported increased RVEF with advancing age, increased RV end-diastolic volume but lower RVEF in men versus women, lower RVEF in black versus white individuals as well as higher right ventricular enddiastolic volume and lower RVEF in obese individuals. 8,9 Several other studies 7,10 have provided normal reference ranges for RV volumes and systolic function using contemporaneous SSFP acquisition, but these are on a much smaller scale than the study by Foppa et al 11 in this issue of Circulation: Cardiovascular Imaging.Foppa et al 11 report sex-specific normative values for RV measurement from a cross-sectional study of members of the Framingham Heart Study Offspring cohort. The reported normal values are derived from the 1336 participants remaining after exclusion of those with a history of either respiratory disease, previous venous thromboembolic disease, or significant left ventricular systolic impairment, ensuring a wellcharacterized sample.…”