Disproportionate exercise load and remodeling of the athlete's right ventricle.

PURPOSE: There is evolving evidence that intense exercise may place a disproportionate load on the right ventricle (RV) when compared with the left ventricle (LV) of the heart. Using a novel method of estimating end-systolic wall stress (ES-σ), we compared the RV and LV during exercise and assessed whether this influenced chronic ventricular remodeling in athletes. METHODS: For this study, 39 endurance athletes (EA) and 14 nonathletes (NA) underwent resting cardiac magnetic resonance (CMR), maximal oxygen uptake (VO2), and exercise echocardiography studies. LV and RV end-systolic wall stress (ES-σ) were calculated using the Laplace relation (ES-σ = Pr/(2h)). Ventricular size and wall thickness were determined by CMR; invasive and Doppler echo estimates were used to measure systemic and pulmonary ventricular pressures, respectively; and stroke volume was quantified by Doppler echocardiography and used to calculate changes in ventricular geometry during exercise. RESULTS: In EA, compared with NA, resting CMR measures showed greater RV than LV remodeling. The ratios RV ESV/LV ESV (1.40 ± 0.23 vs 1.26 ± 0.12, P = 0.007) and RV mass/LV mass (0.29 ± 0.04 vs 0.25 ± 0.03, P = 0.012) were greater in EA than in NA. RVES-σ was lower at rest than LVES-σ (143 ± 44 vs 252 ± 49 kdyn · cm, P < 0.001) but increased more with strenuous exercise (125% vs 14%, P < 0.001), resulting in similar peak exercise ES-σ (321 ± 106 vs 286 ± 77 kdyn · cm, P = 0.058). Peak exercise RVES-σ was greater in EA than in NA (340 ± 107 vs 266 ± 82 kdyn · cm, P = 0.028), whereas RVES-σ at matched absolute workloads did not differ (P = 0.79). CONCLUSIONS: Exercise induces a relative increase in RVES-σ which exceeds LVES-σ. In athletes, greater RV enlargement and greater wall thickening may be a product of this disproportionate load excess.

One- and two-dimensional estimation of right and left ventricular size and function-comparison with cardiac magnetic resonance imaging volumetric analysis.

BACKGROUND: Estimations of right ventricular (RV) and left ventricular (LV) size and function based on 1D and 2D measures are commonly used. However, their correlation with volumetric analysis methods is not well documented. METHODS: We analysed a series of subjects undergoing CMR (n=30). Contiguous short axis cine imaging was obtained to assess RV and LV volumes and function. Standard short and long axis cine imaging were performed to evaluate linear and planimetric dimensions as well as functional analysis. RESULTS: Linear and planimetric measurements of the RV in standard long and short axis views correlated weakly with standard volumetric measurements (r=0.34-0.73). RV ejection fraction (EF), when calculated from single plane functional analysis correlated only moderately with the volumetric EF (r=0.75, p<0.001). In contrast, estimation of LV volumes, mass and EF by biplane area-length method demonstrated excellent correlation with volumetric data (r=0.89, 0.92 and 0.91, p<0.001 for all). CONCLUSION: Two-dimensional estimations of volume and function correlate well with LV volumetric analysis, but not with RV volumetric analysis. Estimation of RV size and function based on linear or planimetric assumption models should be performed and interpreted with caution.

Utility of myocardial fibrosis and fatty infiltration detected by cardiac magnetic resonance imaging in the diagnosis of arrhythmogenic right ventricular dysplasia--a single centre experience.

INTRODUCTION: Cardiac magnetic resonance imaging (CMR) has evolved as a major diagnostic tool to evaluate arrhythmogenic right ventricular dysplasia (ARVD). However, there is a lack of consensus in the interpretation of findings such as fatty infiltration or myocardial fibrosis. We examined the diagnostic utility of these two features in the diagnosis of ARVD. METHODS: We performed fast imaging employing steady-state acquisition cine imaging, T(1)-weighted black blood imaging with and without fat suppression and post-contrast delayed enhancement on a 1.5-T scanner to evaluate ventricular function and morphology, fatty infiltration and regional myocardial fibrosis in 52 subjects with suspected ARVD. RESULTS: Eight subjects met the international diagnostic criteria for ARVD. Right ventricle (RV) delayed hyper-enhancement was found in 7 of 8 (88%) ARVD subjects compared to 6 of 44 (14%) subjects without ARVD (p<0.001). Fatty infiltration was only identified in 1 ARVD patient, and 1 non-ARVD patient. On multiple logistic regression analysis RV enhancement remained an independent predictor for the diagnosis of ARVD (p<0.05). CONCLUSION: RV delayed enhancement is common in patients with ARVD, whereas detection of fatty infiltration of the right ventricle was rare in our patient population. The inclusion of RV fibrosis on CMR as a feature of ARVD may improve the diagnostic accuracy of this condition.