**6. Heart donor recovery**

### **6.1 DBD heart donor using OCS**

After a visual assessment for anatomy and function is completed and the heart is accepted for transplant, the aortopulmonary window, superior and inferior vena cava are dissected. Heparin is given and a cardioplegic cannulation is placed. When the donor is ready for aortic cross-clamp, 1200–1400 ml of donor blood is drained into a pre-heparinized blood collection bag for OCS machine priming, using the right atrial cannula with the tip pointed to the inferior vena cava.

After blood collection, the superior vena cava is occluded. The left-sided heart is vented by cutting left the atrial appendage (LAA) or superior/inferior pulmonary vein if the donor's lung is not being recovered for transplant. The right heart is vented from the previous right atrial appendage incision and augmented by cutting the inferior vena cava above the diaphragm. Then, the aortic cross clamp is applied, and cardioplegia is administered through the aortic cannula using a pressure bag to achieve a quick diastolic arrest [17]. Topical hypothermia is applied using ice slush or cold water until cardioplegia is finished. The donor heart is then removed and transferred to the back table for OCS instrumentation [17].

### **6.2 DCD heart donor using OCS**

All necessary surgical instruments and the donor blood collection bag are prepped and set up at the side table before the procedure begins. Heparin 30,000 IU is given 5 minutes before withdrawal of life support. The donor is observed until 5 minutes after electromechanical arrest to ensure a complete cessation of circulation. Median sternotomy is performed quickly, the right atrial cannula is placed in the distended right atrial appendage connected to pre-heparized blood collection bag to retrieve 1200–1400 ml of donor blood using the OCS machine priming.

After blood collection is finished, the aortic cross clamp is applied, cardioplegia is administered, and the right and left heart are vented as described for the DBD donor. Topical ice slush or cold saline is applied. The donor heart explant is performed in a similar fashion as DBD procurement [17]. The donor heart is then transferred to the back table for OCS instrumentation.

### **6.3 OCS instrumentation**

The donor heart is carefully inspected. Patent foramen ovale or any septum defects are carefully checked and repaired if present to ensure the right heart is a closed system for precise coronary blood flow monitoring via pulmonary artery cannula. Any right and/or left atrial appendage incision made previously for blood donor collection and left-sided heart venting are repaired. The superior vena cava is ligated, and the inferior vena cava is then closed using a polypropylene suture secured with a plastic tourniquet. The ascending aorta and pulmonary artery are cannulated. The left ventricle (LV) is vented by placing an LV vent through the left atriotomy.
