Keywords:
Computer Applications-Detection, diagnosis, Contrast agent-intravenous, Ablation procedures, MR, Cardiac, Outcomes, Connective tissue disorders
Authors:
H. Nivet, G. L. Chevreau, M. Salel, T. Ait Ali, O. Corneloup, V. Latrabe, M. Montaudon, F. Laurent, H. Cochet; Pessac/FR
Methods and Materials
Population
- 26 consecutive patients (age 54±8 years,
1 woman).
- Inclusion criterion : history of cardiac ablation for persistent AF using the stepwise approach with a minimum follow-up of 3 years since first procedure,
and at least 1 year since last procedure without recurrence.
Magnetic Resonance Imaging
- Cine imaging was performed to acquire: a stack of short axis slices covering the left ventricle (LV) from base to apex; a stack of 4 chambers slices covering both atria from roof to bottom; a modified 4-chamber plane comprising left (LAA) and right atrial appendages (RAA),
as well as in 2 chambers and 4 chambers planes
- Trans-mitral and trans-tricuspid flows were measured by using 2-dimensional through-plane phase contrast velocity encoded imaging (3).
- Delayed enhancement imaging: 10 minutes after contrast injection,
in order to acquire 3 stacks of slices in short axis,
2 chambers and 4 chambers planes covering the whole LV; 15 minutes after contrast injection by using a free-breathing high resolution method dedicated to atrial scar imaging (4).
Image Processing
- LV Volumes measurements: end-diastolic volume (EDV),
end-systolic volume (ESV) and ejection fraction (EF).
- Left atrial (LA) and right atrial (RA) volumes measurements: maximal volume,
pre-contraction volume,
and minimal volume.
On each atrium,
total ejection fraction (EF) was calculated as follows: (maximal volume – minimal volume) / maximal volume.
Conduit function (CF) was calculated as: (maximal volume – pre-contraction volume) / maximal volume.
Active emptying fraction (AEF) was calculated as: (pre-contraction volume – minimal volume) / pre-contraction volume.
Reservoir function was analyzed using the expansion index (EI) defined as: (maximal volume – minimal volume) / minimal volume.
- Inter-appendage mechanical delay: expressed in ms.
- Mitral and tricuspid A wave peak velocity: expressed in cm/s.
- Segmentation of atrial scar: using delayed enhanced images of both LA and RA (expressed in % of the atrial wall).