Porcine Heart Excision: A Protocol to Extract Porcine Heart for Cardiac Transplant

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.

1. Blood Collection and Heart Procurement

1. Evaluate the anesthesia level every minimum of 5 min to confirm the surgical plane (no pedal reflex and no blink reflex, no response to painful stimuli).
2. Perform a median sternotomy.
   1. Identify jugulum and xiphoid as landmarks.
   2. Using electrocautery, develop the midline between the landmarks by dividing the subcutaneous tissue and the fascia between the fibers of the pectoralis major muscle.
   3. Mark the midline along the sternal bone with the cautery. Perform sternal osteotomy with an electric or air-powered saw. To prevent creating injuries to the underlying structures (e.g., pericardium and brachiocephalic vein, and innominate artery), proceed gradually with the saw.
   4. Retract the sternum gradually, using a sternal retractor. To avoid excessive tension and vascular injury, do not place the retractor too far cranially.
   5. Free the sternopericardial ligaments from the posterior surface of the sternum using cautery.
   6. Open the pericardium with a Metzenbaum Scissor and fix the pericardial edges to the sternum using 1-0 silk suture.
3. Extend the midline incision cranially by 2–3 cm and expose the right common carotid artery and internal jugular vein.
4. Obtain proximal and distal control of the vessels by encircling the vessels with silk ties (2-0).
5. Tie the cranial encircling ties on each vessel.
6. Open the anterior 1/3 of each vessel with an 11-blade and then insert a 5–6 French (F) sheath into each vessel. Tie the caudal encircling tie around each vessel to secure the respective sheathes.
7. Monitor the arterial and central venous pressures by connecting each sheath to a pressure transducer.
8. Deliver 1,000 U/kg heparin intravenously.
9. Place a 3-0 polypropylene purse-string suture around the right atrial appendage and secure it with a snare.
10. Inside the purse-string suture, create a 1 cm incision on the appendage using an 11 blade. Insert a two-stage venous cannula (28/36 FR) inside the incision and position the distal tip in the inferior vena cava. Secure the cannula by tying a snare to the venous cannula. Control the outlet of the cannula with a tubing clamp.
11. From the two-stage venous cannula placed in the right atrium, collect 750 mL of whole blood from the pig gradually over a period of 15 min into an autoclaved glass container and simultaneously replace the volume with 1 L of an isotonic crystalloid solution such as Plasmalyte A.
12. Place a cardioplegia needle (14–16 F) in the ascending Aorta and secure it with a snare.
13. Connect the cardioplegia cannula to the cardioplegia bag and add 100 mL of blood to 400 mL of cardioplegia (St. Thomas Hospital Solution) to reach a final volume of 500 mL blood cardioplegia.
14. Euthanize the pig by exsanguination.
15. Cross-clamp the ascending aorta with an aortic clamp and deliver the cardioplegic solution into the aortic root.
16. After delivery of the cardioplegic solution is completed, remove the cross-clamp, and perform the cardiectomy.
    1. For ease of attaching the aorta and pulmonary artery to their representative cannula, partially dissect the ascending aorta from the pulmonary artery using Metzenbaum scissors.
    2. Transect the superior and inferior vena cava, leaving roughly 1 cm of length on each.
    3. Separate the heart from the posterior mediastinum by transecting the pulmonary veins.
    4. Excise the heart ensuring all the aortic arch vessels are procured along with a segment of descending aorta. Preserve up to the pulmonary artery bifurcation.
17. Weigh the empty heart. The amount of weight gain over the ex-situ preservation interval can be used as a metric for organ edema.