Effects of steady state free precession parameters on cardiac mass, function, and volumes

G0400444/Medical Research Council/United Kingdom Wellcome Trust/United Kingdo

3T MRI investigation of cardiac left ventricular structure and function in a UK population:The tayside screening for the prevention of cardiac events (TASCFORCE) study

Contract grant sponsor: Souter Charitable Trust, and Chest, Heart and Stroke Scotland; Contract grant sponsor: Wellcome Trust; contract grant number: WT 085664 (Clinical Research Fellowship to J.W-McC.)Purpose : To scan a volunteer population using 3.0T magnetic resonance imaging (MRI). MRI of the left ventricular (LV) structure and function in healthy volunteers has been reported extensively at 1.5T. Materials and Methods : A population of 1528 volunteers was scanned. A standardized approach was taken to acquire steady-state free precession (SSFP) LV data in the short-axis plane, and images were quantified using commercial software. Six observers undertook the segmentation analysis. Results : Mean values (±standard deviation, SD) were: ejection fraction (EF) = 69 ± 6%, end diastolic volume index (EDVI) = 71 ± 13 ml/m2 , end systolic volume index (ESVI) = 22 ± 7 ml/m2 , stroke volume index (SVI) = 49 ± 8 ml/m2 , and LV mass index (LVMI) = 55 ± 12 g/m2 . The mean EF was slightly larger for females (69%) than for males (68%), but all other variables were smaller for females (EDVI 68v77 ml/m2 , ESVI 21v25 ml/m2 , SVI 46v52 ml/m2 , LVMI 49v64 g/m2, all P < 0.05). The mean LV volume data mostly decreased with each age decade (EDVI males: -2.9 ± 1.3 ml/m2 , females: -3.1 ± 0.8 ml/m2 ; ESVI males: -1.3 ± 0.7 ml/m2 , females: -1.7 ± 0.5 ml/m2 ; SVI males: -1.7 ± 0.9 ml/m2 , females: -1.4 ± 0.6 ml/m2 ; LVMI males: -1.6 ± 1.1 g/m2 , females: -0.2 ± 0.6 g/m2 but the mean EF was virtually stable in males (0.6 ± 0.6%) and rose slightly in females (1.2 ± 0.5%) with age. Conclusion : LV reference ranges are provided in this population-based MR study at 3.0T. The variables are similar to those described at 1.5T, including variations with age and gender. These data may help to support future population-based MR research studies that involve the use of 3.0T MRI scanners.Publisher PDFPeer reviewe

Long-term outcomes of cardiac resynchronization therapy in adult congenital heart disease

Background and Aims: Randomized, controlled trials of cardiac resynchronization therapy (CRT) excluded patients with adult congenital heart disease (ACHD). We sought to explore long-term clinical outcomes. Methods and Results: In this single-center, observational study, events were collected from hospital records on patients with structural ACHD (sACHD) and adults with ischemic (ICM) or nonischemic (NICM) cardiomyopathy undergoing CRT. Patients with sACHD (n = 23, age: 41.6 ± 13.5 years [mean ± standard deviation]) and adults with ICM (n = 533) or NICM (n = 458) were followed-up for 4.1 years (median; interquartile range: 2.2-6.1). Total mortality was 5/23 (21.7%; 4.4 per 100 person-years) in sACHD, 221/533 (41.5%; 11.8 per 100 person-years) in ICM, and 154/458 (33.6%; 9.7 per 100 person-years) in NICM. In univariate analyses, total mortality in sACHD was lower than in ICM (hazard ratio [HR]: 0.38; 95% confidence interval [CI] 0.15-0.91), but similar to NICM (HR: 0.48, 95% CI 0.20-1.16). Cardiac mortality in sACHD was similar to ICM (HR: 0.78, 95% CI 0.32-1.92) and NICM (HR: 1.12, 95% CI 0.45-2.78). Heart failure (HF) hospitalization rates were similar to ICM (HR: 0.44, 95% CI 0.11-1.77) and NICM (HR: 0.75, 95% CI 0.18-3.08). In multivariate analyses, no differences emerged in total mortality, cardiac mortality, or HF hospitalization between sACHD and NICM or ICM, after adjustment for age, sex, New York Heart Association class, diabetes, atrial rhythm, QRS duration, QRS morphology, systemic ventricular ejection fraction, and medical therapy. Conclusion: Total mortality, cardiac mortality, and HF hospitalization after CRT in patients with sACHD was similar to adults with ICM or NICM

Numerical simulation of electrocardiograms for full cardiac cycles in healthy and pathological conditions

This work is dedicated to the simulation of full cycles of the electrical activity of the heart and the corresponding body surface potential. The model is based on a realistic torso and heart anatomy, including ventricles and atria. One of the specificities of our approach is to model the atria as a surface, which is the kind of data typically provided by medical imaging for thin volumes. The bidomain equations are considered in their usual formulation in the ventricles, and in a surface formulation on the atria. Two ionic models are used: the Courtemanche-Ramirez-Nattel model on the atria, and the "Minimal model for human Ventricular action potentials" (MV) by Bueno-Orovio, Cherry and Fenton in the ventricles. The heart is weakly coupled to the torso by a Robin boundary condition based on a resistor- capacitor transmission condition. Various ECGs are simulated in healthy and pathological conditions (left and right bundle branch blocks, Bachmann's bundle block, Wolff-Parkinson-White syndrome). To assess the numerical ECGs, we use several qualitative and quantitative criteria found in the medical literature. Our simulator can also be used to generate the signals measured by a vest of electrodes. This capability is illustrated at the end of the article