A Swine Model of Percutaneous Intracoronary Ethanol Induced Acute Myocardial Infarction and Ischemic Mitral Regurgitation

Abstract

Ischemic mitral regurgitation (IMR) is a frequent complication after a myocardial infarction (MI), which doubles mortality. Transcatheter mitral repairs are emerging as alternative treatment options to open heart surgery for IMR, but animal models to test them are lacking. We report a percutaneous swine model of IMR. Seventeen swine were randomized to (group 1, n = 12) MI causing IMR, and (group 2, n = 5) controls. In group 1, MI was induced via percutaneous ethanol injection into the obtuse marginal branches of the left circumflex artery, resulting in ST elevating myocardial infarction. Nine animals were survived to 8-10 weeks with weekly echocardiograms and three swine were survived to 16-20 weeks with MRI at termination. In group 1 animals, average IMR fraction at termination was 26.6 ± 2.3% in the echo group, and 24.51 ± 0.41% in the MRI group. None of the animals in group 2 had IMR. Left ventricular dysfunction and significant dilatation were evident in group 1 animals, compared to the controls. In conclusion, a reproducible model of IMR is reported for use in pre-clinical testing of new mitral technologies.

The characteristics of a porcine mitral regurgitation model

“…Myocardial infarction in the posterior papillary muscle region can lead to displacement of the papillary muscles, which can itself cause mitral regurgitation. The target vessels for ischaemic mitral regurgitation are OM1, OM2, OM3, or OM4 in the left circumflex coronary artery [ 33 ], in some cases including the posterior descending branch of the right coronary artery [ 19 ]. This process can be completed by injecting procoagulant material into the target vessel under intervention [ 33 ] or ligating the coronary artery [ 19 ].…”

“…The target vessels for ischaemic mitral regurgitation are OM1, OM2, OM3, or OM4 in the left circumflex coronary artery [ 33 ], in some cases including the posterior descending branch of the right coronary artery [ 19 ]. This process can be completed by injecting procoagulant material into the target vessel under intervention [ 33 ] or ligating the coronary artery [ 19 ]. Because of the variation of the coronary artery distribution, the myocardial infarction area is uneven after the blood flow is interrupted.…”

Heart Valve Biomechanics: The Frontiers of Modeling Modalities and the Expansive Capabilities of Ex Vivo Heart Simulation

“…Early work using large animals primarily centered around ischemic modeling, as coronary vasculature ligation or percutaneous ethanol injection provides straightforward mechanisms for inducing targeted infarction and subsequent ischemia (100)(101)(102)(103)(104). In studying ischemic valvular biomechanics, researchers have used these models to analyze a wide variety of phenomena such as ischemic remodeling of MV annular dynamics, surgical techniques, such as posterior leaflet augmentation and chordal cutting, the relationship between ischemic MR and ventricular remodeling, and the effects of annuloplasty ring selection and sizing for ischemic MR repair (102,103,(105)(106)(107)(108)(109)(110)(111)(112)(113). While studies such as these have shown the power of in vivo modeling capabilities, there are some key limitations with this line of research.…”

A Randomized Porcine Study in Low Cardiac Output of Vasoactive and Inotropic Drug Effects on the Gastrointestinal Tract

“…This model is therefore reasonable for investigations of drug effects on the gastrointestinal tract. Other relevant models include induction of cardiac tamponade, direct aortic, or mesenteric in-flow restriction and open-and closed-chest models of acute cardiac ischemia (15,(22)(23)(24)(25)(26). However, in this study, the intention was to induce and maintain a predetermined level of CO, which was accomplished, to isolate peripheral vasoactive effects from inotropy.…”