https://doi.org/10.1007/s00392-025-02625-4
1Universitäts-Herzzentrum Freiburg - Bad Krozingen Klinik für Kardiologie und Angiologie Freiburg im Breisgau, Deutschland; 2Dept. of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg Division of Medical Physics Freiburg, Deutschland; 3Universitäts-Herzzentrum Freiburg - Bad Krozingen Innere Medizin III, Kardiologie und Angiologie Freiburg im Breisgau, Deutschland; 4Albert- Ludwigs-Universität Freiburg Innere Medizin III, Kardiologie und Angiologie Freiburg im Breisgau, Deutschland; 5Max Grundig Klinik Kardiologie Bühl, Deutschland
Background: The porcine closed-chest model of ischemia-reperfusion injury (IRI) by temporary balloon-occlusion of a coronary artery is an essential tool for preclinical research in Cardiology. Current literature reports conflicting results with this model. This retrospective analysis presents our cardiac magnetic resonance (CMR) findings and experience while establishing this model.
Methods:
20 juvenile German Landrace pigs received general anaesthesia and antiarrhythmic pretreatment. Myocardial ischemia was induced using transfemoral catheterization and balloon-occlusion of a coronary artery under x-ray fluoroscopy guidance. Either the left anterior descending (LAD) or the left circumflex coronary artery was occluded. The duration of ischemia varied from 30 to 90 minutes. CMR was performed at a clinical 3T system to assess myocardial injury including quantitative T1 and T2 mapping and LGE. 10 pigs underwent CMR 2-5 hours following reperfusion, five pigs three days post-reperfusion.
In a separate series an MRI-guided closed-chest LAD occlusion was tested and performed in two animals.
Results:
Ventricular fibrillation (VF) was a recurrent event, which was counteracted with propranolol in addition to amiodarone and high blood potassium levels. 75 % of pigs survived the experiment. 47 % of the included pigs required resuscitation. Males were 9.8 times more likely to experience VF than females. CMR revealed IRI in 14 of 15 animals. It was located in areas analogous to those supplied by the respective artery in humans. Regional T1 and T2 map values both increased with longer ischemic durations. An ischemia duration over 60 minutes was associated with elevated T2 map values (p = 0.026), while elevations in T1 map values were also evident after short ischemia (p = 0.024). 60-90 minutes of ischemia induced greater mapping value elevations than 30-45 minutes of ischemia (p = 0.0001 for T1 map and p = 0.021 for T2 map). LGE occurred following occlusion durations of 60-90 minutes. The mean ejection fraction was reduced and 47 % of animals had an impaired wall motion following coronary occlusion.
In the MRI-guided approach one animal underwent 90 minutes of LAD-occlusion and the non-perfused LV segments could clearly be distinguished on CMR during the procedure. This was followed by fatal VF directly post-reperfusion. A second animal died during coronary occlusion in the MRI scanner.
Conclusions:
State of the art CMR sequences characterized porcine myocardial IRI, showing varying T1 and T2 map patterns after different ischemia and reperfusion durations. Significant myocardial infarction indicated by LGE occurred after ischemic durations over 60 minutes in juvenile German Landrace pigs. This data can support choosing an appropriate occlusion duration for distinct scientific purposes.
We successfully induced MRI guided myocardial ischemia and were able to monitor IRI in real-time. However, fluoroscopy guidance proved to be more practicable than MRI guidance due to limited resuscitation measures.