Myocardial infarction (MI) animal models that emulate the natural process of the disease in humans are crucial to understanding pathophysiological mechanisms and testing the safety and efficacy of new emergent therapies. Here, we describe an MI swine model created by deploying a percutaneous embolization coil.
This protocol is important because it allows performing myocardial infarction in a translational animal model, in a feasible and reproducible way similar to human. The main advantage of this procedure is that it avoids the traditional open-chest surgery and the subsequent postoperative inflammation. And therefore is one of the best choices mimicking human myocardial infarction.
This technique is suitable for modeling myocardial infarction and higher failure depending on the dissection of the ischemic area. Begin by placing the anesthetized animal on the operating table in the supine position and fix the limbs to the table with tape or bandage. Place the electrocardiogram probes subcutaneously in the animals'extremities for recording changes in the ST-segment, T-waves and heart rate during the experimental procedure.
Place the pulse oximeter on the tongue or a corner of the animal's lip and the non-invasive pressure cuff on the for limb. Measure the temperature with a esophageal probe. Clean the right femoral area with surgical soap followed by alternating antiseptic povidone-iodine solution and alcohol three times under sterile conditions.
Wash the hands surgically and wear sterile gown and sterile gloves. Then cover the animal with a sterile surgical drape. Flush the needle vascular sheath J-tipped wire, guiding catheter, guidewire microcatheter, and the contrast medium injection manifold kit with heparinized saline solution.
Locate the bifurcation between the superficial and deep femoral arteries using ultrasound. Position the transducer two to three centimeters proximal to the bifurcation in the common femoral artery and align the center of the transducer with the common femoral artery. Now position the needle in the center of the transducer and puncture the artery at angulation of approximately 45 degrees.
Subsequently, insert a six French vascular sheath using the modified Seldinger technique and administer heparin through the sheath. Begin by inserting the J-tip wire into the JR4r guide catheter and advance the wire through the sheath into the ascending aorta. Place the catheter up over the valvular surface.
After removing the wire connect the catheter to the injection manifold system and purge the entire system. Under fluoroscopy, engage the catheter into the left main coronary artery and inject 10 milliliters of iodinated contrast medium to visualize the left coronary system. Perform angiograms in the left anterior oblique 40 degrees and right anterior oblique 30 degrees projections.
Under fluoroscopic guidance, advance 0.014-inch guidewire pre-assembled on the microcatheter to the middle left anterior descending or distal left circumflex coronary artery. Under fluoroscopic guidance, advance the microcatheter through the wire to the desired location where the coil implant should be deployed. Remove the wire and select the coil.
Deliver the coil via microcatheter and slowly inject five milliliters of iodinated contrast medium under fluoroscopy to visualize the correct position of the coil. Place the wire in a side branch to perform control injections and to ensure access to the artery if a second coil needs to be implanted. Wait for the coil to thrombose and occlude the artery.
57 pigs underwent coronary coil implantation and their angiographic showed myocardial infarction in the distal left circumflex marginal branch or distal left anterior descending coronary artery. The mortality of this model was 19%related to complications of MI.Magnetic resonance imaging analysis of the left circumflex marginal branch and distal left anterior descending coronary infarctions was performed in all animals 30 days post myocardial infarction. The coil deployment in the left circumflex marginal coronary artery affected the left ventricular lateral wall.
While the intra-ventricular septum is the most affected area in distal left anterior descending coronary placement. The infarcted areas post coil development in the left circumflex marginal coronary artery and the distal left anterior descending coronary were also confirmed after heart sectioning. The most important steps include, first, to place the microcatheter in the right position.
Second, to choose the correct coil size and third to deliver it properly. Thanks to this model, researchers can explore new therapies and study the pathophysiological mechanism of myocardial infarction.
