**6.9 Normothermic regional perfusion**

This perfusion method likely resembles the first heart transplant technique done by Christiaan Barnard. Once the donor is declared dead, a sternotomy is performed. There are two types of Normothermic regional perfusion (NRP) depending on which organs are planned for recovery. Four units of washed-packed red blood cells are prepared by the hospital blood bank for NRP circuit priming.

1.Thoracoabdominal normothermic regional perfusion (TA-NRP) (**Figure 5**) is used when the heart and/or lungs along with abdominal organs are procured. First, the cerebral circulation is excluded before restoring perfusion by clamping

### **Figure 5.**

*Thoracoabdominal NRP (TA-NRP). The ascending aorta and right atrium are cannulated. The innominate artery, the left common carotid artery and the left subclavian artery are clamped.*

the three cephalic vessels, (the innominate, left common carotid artery and left subclavian arteries). The organs are then re-perfused by initiating veno-arterial extracorporeal membrane oxygenation (VA-ECMO) or cardiopulmonary bypass using central cannulation of ascending aorta and right atrium [48].

2.Abdominal normothermic regional perfusion (A-NRP) (**Figure 6**) is performed if only the abdominal organs are being recovered. The femoral artery and vein or abdominal aorta or inferior vena cava are cannulated. To exclude cerebral perfusion, the abdominal aorta is clamped below the diaphragm. Alternatively, an intraaortic balloon occluder can be used, inserted via the abdominal aorta incision, advanced, and inflated in the thoracic aorta. The inferior vena cava is also clamped to prevent cerebral and thoracic recirculation [50].

#### **Figure 6.**

*Abdominal NRP (A-NRP). The femoral artery and femoral vein are cannulated. Veno-arterial ECMO circuit is similar for both Thoracoabdominal NRP and abdominal NRP.*

## *Heart Preservation Techniques for Transplantation DOI: http://dx.doi.org/10.5772/intechopen.113937*

TA-NRP is initiated with the targeted flow at 5 L/min. The heart usually starts beating within 2–3 minutes. If the heart fibrillates, an internal defibrillation (10 J) is delivered. The heart visualization is first inspected. Inotropes or vasopressors are titrated to maintain a mean arterial blood pressure > 50 mmHg. Functional assessment is performed with transesophageal echocardiography (TEE) and pulmonary artery catheter monitoring. The donor is reintubated and ventilated with low tidal volume to avoid atelectasis which would increase pulmonary vascular resistance. As the heart function continues to improve, all inotropes and vasopressors are weaned. Arterial blood gas (ABG) and lactate are obtained to evaluate and confirm adequate perfusion. NRP will continue for 45–90 minutes depending on cardiac contractility [12]. The donor is then weaned off from NRP circuit to visualize unsupported cardiac function. Criteria for acceptance include LVEF ≥50% by TEE, cardiac index (CI) ≥ 2.5 L/min/m2 , central venous pressure ≤ 12 mmHg and pulmonary capillary wedge pressure ≤ 12 mmHg [48]. If the heart is accepted, cold cardioplegia is administered to arrest the heart [51]. Heart explantation and venting are the same as those of DBD heart procurement. For transportation, the heart can be preserved using traditional static cold storage, a temperature-controlled heart transport system or re-perfused with an OCS system [12, 46].

Utilizing OCS after NRP could minimize cold ischemic time compared to using static cold storage. Moreover, in case of complicated redo-sternotomy recipients requiring additional time for mediastinal dissection, OCS provides extra time to achieve a meticulous dissection after the donor heart arrives at the recipient's operating room [50].

NRP provides early continuous physiologic warm blood perfusion, restores cardiac function and establishes perfusion of other organs concomitantly. NRP could reduce the additional cost of *ex-vivo* perfusion machines for each individual organ. Although the NRP is considered less expensive when combined with static cold storage compared with the OCS system [20]. NRP has not been accepted in some regions of the US due to ethical issues related to the NRP protocol (cerebral reperfusion may still occur despite clamping of cephalic vessels [8, 20, 51].
