Firstly, the heart must be removed from the chest cavity of the animal using either of two surgical procedures:
- Median sternotomy: An incision is made along the sternum, after which the sternum itself is divided (or "cracked") to expose the heart; OR
- Bilateral sternotomy: Two incisions are made on both sides of the sternum to expose the chest cavity.
After successful extraction, the heart is then immersed in an ice-cold solution or semi-frozen solution.
The heart is then cannulated using one of the two following methods:
- The Vertical method: The aorta is identified while the heart is maintained on an ice-bed. The aorta is then quickly cannulated without the use of a microscope. The aorta is then clipped onto the cannula for support before tying it off with a suture (thread). It is recommended that the researcher keep a container of semi-frozen solution in close proximity to maintain the heart during the cannulation process.
- The Horizontal method: The cannula (previously filled with perfusate using a three-way tap) is detached from the perfusion system and attached to a micro-positioner. The micro-positioner is then used to manouver the cannula horizontally above the heart. The aorta is identified under a microscope and then cannulated while lying on an ice-bed. After the aorta is cannulated, the heart and the cannula are reattached to the perfusion system. Care must be taken to ensure no air bubbles enter the perfusion system.