Left ventricular blood flow patterns at rest and under dobutamine stress in healthy pigs. (7th November 2018)

• Record Type: Journal Article
• Authors: Cesarovic, Nikola; Busch, Julia; Lipiski, Miriam; Fuetterer, Maximilian; Fleischmann, Thea; Born, Silvia; von Deuster, Constantin; Sauer, Mareike; Maisano, Francesco; Kozerke, Sebastian; Stoeck, Christian T.
• Is Part Of: NMR in biomedicine. Volume 32:Number 1(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-11-07
• Subjects: 4D flow -- dobutamine stress -- left ventricular flow pattern -- porcine heart -- vortex formation; Nuclear magnetic resonance -- Periodicals; Magnetic Resonance Spectroscopy -- Periodicals; 574
• DOI: 10.1002/nbm.4022
• Languages: English
• ISSNs: 0952-3480

Abstract

Abstract : Intracardiac blood flow patterns are affected by the morphology of cardiac structures and are set up to support the heart's pump function. Exercise affects contractility and chamber size as well as pre‐ and afterload. The aim of this study was to test the feasibility of four‐dimensional phase contrast cardiovascular MRI under pharmacological stress and to study left ventricular blood flow under stress. 4D flow data were successfully acquired and analysed in 12 animals. During dobutamine infusion, heart rate and ejection fraction increased (82 ± 5 bpm versus 124 ± 3 bpm/46 ± 9% versus 65 ± 7%; both p < 0.05). A decrease in left ventricular end‐diastolic volume (72 ± 14 mL versus 55 ± 8 mL; p < 0.05) and end‐systolic volume (40 ± 15 mL versus 19 ± 6 mL; p < 0.05) but no change in stroke volume were observed. Trans‐mitral diastolic inflow velocity increased under dobutamine and the trajectory of inflowing blood was directed towards the anterior septum with increased inflow angle (26 ± 5°) when compared with controls (15 ± 2°). In 5/6 animals undergoing stress diastolic vortices developed later, and in 3/6 animals vortices collapsed earlier with significantly smaller cross‐sectional area during diastole. The vorticity index was not affected. Under the stress condition direct flow (% ejection within the next heart beat) increased from 43 ± 6% to 53 ± 8%. 4D MRI blood flow acquisition and analysis are feasible in pig hearts under dobutamine‐induced stress. Flow patterns characterized by high blood velocity and antero‐septally oriented diastolic inflow as well as decreased ventricular volumes are unfavourable conditions for diastolic vortex development under pharmacological stress, and cardiac output is increased by a rise in heart rate and directly ejected left ventricular blood volume. Abstract : In this study the feasibility of 4D flow MRI during dobutamine‐induced stress was assessed, and changes in intraventricular blood flow patterns are reported for the porcine heart. A decrease in cardiac volume, antero‐septally oriented diastolic inflow and high velocity flow was found, providing unfavorable conditions for diastolic vortex development compared with the rest condition.