Magnetic resonance-compatible model of isolated working heart from large animal for multimodal assessment of cardiac function, electrophysiology, and metabolism

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 310; no. 10; p. H1371
• Main Authors: Vaillant, Fanny, Magat, Julie, Bour, Pierre, Naulin, Jérôme, Benoist, David, Loyer, Virginie, Vieillot, Delphine, Labrousse, Louis, Ritter, Philippe, Bernus, Olivier, Dos Santos, Pierre, Quesson, Bruno
• Format: Journal Article
• Language: English
• Published: United States 15-05-2016
• Subjects: Action Potentials; Adenosine Triphosphate - metabolism; Animals; Arterial Pressure; Electrophysiologic Techniques, Cardiac; Energy Metabolism; Feasibility Studies; Heart - physiology; Heart Rate; Hemodynamics; Isolated Heart Preparation - methods; Kinetics; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Myocardium - metabolism; Perfusion; Phosphocreatine - metabolism; Sheep, Domestic; Stroke Volume; Sus scrofa; Ventricular Function, Left; Ventricular Function, Right; Ventricular Pressure; magnetic resonance imaging and spectroscopy; cardiac function; metabolism; electrophysiology; isolated working pig heart
• ISSN: 1522-1539
• DOI: 10.1152/ajpheart.00825.2015

To provide a model close to the human heart, and to study intrinsic cardiac function at the same time as electromechanical coupling, we developed a magnetic resonance (MR)-compatible setup of isolated working perfused pig hearts. Hearts from pigs (40 kg, n = 20) and sheep (n = 1) were blood perfused ex vivo in the working mode with and without loaded right ventricle (RV), for 80 min. Cardiac function was assessed by measuring left intraventricular pressure and left ventricular (LV) ejection fraction (LVEF), aortic and mitral valve dynamics, and native T1 mapping with MR imaging (1.5 Tesla). Potential myocardial alterations were assessed at the end of ex vivo perfusion from late-Gadolinium enhancement T1 mapping. The ex vivo cardiac function was stable across the 80 min of perfusion. Aortic flow and LV-dP/dtmin were significantly higher (P < 0.05) in hearts perfused with loaded RV, without differences for heart rate, maximal and minimal LV pressure, LV-dP/dtmax, LVEF, and kinetics of aortic and mitral valves. T1 mapping analysis showed a spatially homogeneous distribution over the LV. Simultaneous recording of hemodynamics, LVEF, and local cardiac electrophysiological signals were then successfully performed at baseline and during electrical pacing protocols without inducing alteration of MR images. Finally, (31)P nuclear MR spectroscopy (9.4 T) was also performed in two pig hearts, showing phosphocreatine-to-ATP ratio in accordance with data previously reported in vivo. We demonstrate the feasibility to perfuse isolated pig hearts in the working mode, inside an MR environment, allowing simultaneous assessment of cardiac structure, mechanics, and electrophysiology, illustrating examples of potential applications.