Scholarly article on topic '4D flow CMR detects progressive improvement in ventricular function following cardioversion of atrial fibrillation'

4D flow CMR detects progressive improvement in ventricular function following cardioversion of atrial fibrillation Academic research paper on "Medical engineering"

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Academic research paper on topic "4D flow CMR detects progressive improvement in ventricular function following cardioversion of atrial fibrillation"

Erixon et al. Journal of Cardiovascular Magnetic Resonance 2016, 18(Suppl 1):O89 http://www.jcmr-online.com/content/18/S1/O89

Journal of Cardiovascular Magnetic Resonance

ORAL PRESENTATION

Open Access

4D flow CMR detects progressive improvement in ventricular function following cardioversion of atrial fibrillation

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Hanna Erixon , Jonatan Eriksson , Ann Bolger , Tino Ebbers , Lars Karlsson , Carl Johan Carlhall

From 19th Annual SCMR Scientific Sessions Los Angeles, CA, USA. 27-30 January 2016

Background

Atrial fibrillation (AF) causes impairment of cardiac hemodynamics and substantial cardiovascular morbidity. While AF is difficult to assess with cardiac gated CMR, successful electrical cardioversion of chronic AF is often followed by a transient period of atrial stunning where absence of mechanical atrial contraction, similar to that seen in AF, persists despite reinstitution of sinus rhythm. 4D flow CMR enables assessment of ventricular function according to the volume and kinetic energy of different LV flow components. The volume and end-dia-stolic kinetic energy (KE) of LV inflow passing directly to ensuing outflow (Direct flow) reflect aspects of left atrial-ventricular coupling and have been proven to be markers of LV dysfunction in failing hearts. In this study we hypothesize that left atrial (LA) stunning will contribute to impaired LV function reflected by reduced volume and end-diastolic KE of the LV Direct flow component.

Methods

Eight patients (65 ± 6 years, 1 female) with a history of AF underwent CMR 2-3 hours (scan 1) and 4 weeks (scan 2), respectively, following electrical cardioversion. 4D phase-contrast velocity data and morphological images were acquired at 3T at both scans. A previously validated method was used for the analysis (Eriksson et al., JCMR 2010): The LV endocardium was segmented from short-axis images at end-diastole (ED) and end-systole. Pathlines were emitted from the LV end-diastolic volume (EDV) and traced forward and backward in time until end-systole. Accordingly, the end-diastolic blood volume could be

1Div. of Cardiovascular Medicine, Linkôping University, Linkôping, Sweden Full list of author information is available at the end of the article

Bio Med Central

Basfline Follow-up P-vahie

LA area fraction (%) 20 ±6 31 ±5 0.001

LV EDV-index (ml/m2) 85 ± 13 89 ± 14 0093

LV ejection fraction (%) 54 ±8 61 ±5 0.003

Volume ratio (% of EDV)

Direct flow 30 ±7 37 ±7 0,001

Retained inflow 20 ±3 19 ±2 0.495

Delayed ejection flow 18 ± 3 19±4 0.252

Residual volume 33±6 25 ±5 0.001

KE ratio at ED (% of EDV)

Direct flow 43 ±10 54 ± 11 0.011

Retained inflow 21 ±4 13 ±6 0.018

Delayed ejection flow 21 i 5 26± 11 0.174

Residual volume 16 ±7 7±3 0.005

ED, end-diastole; EDV, end-diastolic volume; KE, kinetic energy; LA area fraction, left atrial area fraction (maximum area-minimum areaVmaximum area; LV, left ventricle

Figure 1 Left heart dimensions and left ventricular 4D flow measures.

automatically separated into four different functional flow components (Table). The KE was calculated over the cardiac cycle for these flow components based on the volume occupied by each pathline, its velocity, and blood density.

Results

LA area fraction increased over the follow-up period (P = 0.001), indicating recovery of LA mechanical function (Figure 1). There was no difference in LVEDV-index between the two scans (P = 0.093) whereas LV ejection fraction increased over time (P = 0.003). Regarding 4D flow measures, the Direct flow/EDV volume-ratio and KE-ratio at ED increased (P = 0.001 and P = 0.011, respectively), and the Residual volume/EDV volume-ratio

© 2016 Erixon et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http:// creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/ zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Erixon et al. Journal of Cardiovascular Magnetic Resonance 2016, 18(Suppl 1):O89 http://www.jcmr-online.com/content/18/S1/O89

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and KE-ratio at ED decreased (P = 0.001 and P = 0.005, respectively) over time.

Conclusions

Loss of LA mechanical activity may be a contributor to LV dysfunction and heart failure in AF. During the period of LA stunning following cardioversion, the volume and end-diastolic KE of the Direct flow demonstrated impairment of LV function which improved with recovery of LA mechanical function by 4 weeks later. 4D flow specific parameters also showed that the volume and end-diastolic KE of LV residual blood, which may contribute to ventricular inefficiency and stasis of blood, diminished with return of LA mechanical activity. These 4D flow-specific measures may reflect novel aspects of the ventricular benefits of reinstitution of sinus rhythm in the AF patient.

Authors' details

1Div. of Cardiovascular Medicine, Linköping University, Linköping, Sweden. 2Div. of Cardiology, University of California San Francisco, San Francisco, CA, USA.

Published: 27 January 2016

doi:10.1186/1532-429X-18-S1-O89

Cite this article as: Erixon et al.: 4D flow CMR detects progressive improvement in ventricular function following cardioversion of atrial fibrillation. Journal of Cardiovascular Magnetic Resonance 2016 18(Suppl 1): O89.

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