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Introduction Atrial tachyarrhythmia is regarded as a late consequence of the Fontan circulation, particularly in those with an AP Fontan and is associated with significant morbidity and mortality. Developing methods to recognise those at the highest risk will allow early intervention, improving patient outcomes. Purpose To establish relationship between AP Fontan chamber (FC) dimensions, ventricular volumes and function and the development of atrial arrhythmia (AR). Methods Modified AP Fontan patients with CMR (1.5T, Avanto, Siemens) were reviewed (Figure 1). Horizontal long axis (HLA, TrueFISP cine, flip angle 80, TR/TE 50/1.26ms, retrospective ECG gating) and transaxial 3D MRA non-contrast (Modified Siemens Whole Heart coronary artery sequence, respiratory navigator, ECG-triggered, free breathing, slice thickness 2.00mm) of the FC and the left atrium were examined. Results 55 patients 58% female and 42% male, mean age 33yrs (SD 7.9). 32 patients suffered a documented AR, most commonly atrial flutter (79%). There was a significant difference in age between the two groups with those having an AR tending to be older (36yrs vs 29yrs p 0.05). There were no significant differences in atrial parameters between the two groups (p > 0.05), however all measures of the FC were statistically different with larger measures occurring in the AR group (p Conclusions Increasing AP FC size is associated with increased risk of AR.

To determine the accuracy of visual analysis of left ventricular (LV) function in comparison with the accepted quantitative gold standard method, Cardiac Magnetic Resonance (CMR). Cine CMR imaging was performed at 1.5 T on 44 patients with a range of ejection fractions (EF, 5-80%). Clinicians (n = 18) were asked to visually assess EF after sequentially being shown cine images of a four chamber (horizontal long axis; HLA), two chamber (vertical long axis; VLA) and a short axis stack (SAS) and results were compared to a commercially available analysis package. There were strong correlations between visual and quantitative assessment. However, the EF was underestimated in all categories (by 8.4% for HLA, 8.4% for HLA + VLA and 7.9% for HLA + VLA + SAS, P all < 0.01) and particularly underestimated in mild LV impairment (17.4%, P < 0.01), less so for moderate (4.9%) and not for severe impairment (1%). Assessing more than one view of the heart improved visual assessment of LV, EF, however, clinicians underestimated EF by 8.4% on average, with particular inaccuracy in those with mild dysfunction. Given the important clinical information provided by LV assessment, quantitative analysis is recommended for accurate assessment. © 2010 Springer Science+Business Media, B.V.

Methods Cine cardiac MR imaging was performed on 44 subjects with a range of ejection fractions on a 1.5 T Siemens clinical scanner. Clinicians (N = 18) with varying degrees of cardiac MR experience (0 to 13 years) were shown cine images of a four chamber (horizontal long axis; HLA), two chamber (vertical long axis; VLA) and a stack of short axis stack (SAS) images. They were asked to visually assess the ejection fraction (EF) after seeing 10 cardiac cycles of a HLA alone, then HLA + VLA, then the HLA + VLA +SAS. These results were compared to a commercial available LV analysis package (Argus processing).

Introduction Standard MRI assessment of right ventricular (RV) volume and mass is based on assessment of a stack of "standard" short axis images (fig. 1) obtained with respect to the horizontal long axis of the heart. A "modified" RV short axis stack of images, based on cross-sections of the RV outflow long axis (fig. 2), has recently been demonstrated to overcome observed inaccuracies in definition of the tricuspid valve plane for the "standard" image stacks, and therefore to result in less interobserver variability and more reliable RV volume estimates in subjects with anatomically and functionally normal RVs.