**4. Heart dissection and explantation technique**

The donor is positioned, prepped and draped from the chin to the pubis. A midline incision is routinely performed for heart and lung dissection procedures along with a midline incision simultaneously made by abdominal surgeon for abdominal organs retrieval. Visual inspection is achieved to evaluate atrial and ventricular sizes, anatomic variations and cardiac contractility. Surface palpation is performed to evaluate coronary artery calcification, ischemic scarring, contusion and to detect thrills or abnormal flows. Pericardial stay sutures are placed bilaterally and secured with snaps on each side to allow lung evaluation in case of concurrent heart and lung retrieval. Some surgeons prefer minimal dissection to avoid arrhythmia and hemodynamic instability that may occur during heart manipulation. Preliminary dissection of key structures is mostly performed on all organs before heparin is given and cannulation. The ascending aorta and the main pulmonary artery are carefully dissected and separated to allow sufficient aortic cross-clamp placement and manipulate the ascending aorta safely and easily. The superior vena cava (SVC) is dissected off the right pulmonary artery circumferentially. The azygous vein is identified and may be encircled, ligated and finally divided after cardioplegia given to avoid massive bleeding. The inferior vena cava (IVC) is dissected to ensure adequate length. All procurement teams should communicate the timing of their preliminary dissection and readiness to proceed to heparinization [17].

Intravenous heparin (400 U/kg) is given before cannulation. The aortic cannulation site is prepared by placing a 4–0 polypropylene purse-string suture. 14 Fr aortic cannular is placed and secured. The antegrade cardioplegia line is de-aired and connected. The SVC is clamped or tied above the azygous vein. The IVC is partially cut. A pool-tip suction tubing should be inserted into the IVC to facilitate abdominal perfusate drainage and prevent right heart distension. To ensure the left ventricle is decompressed, left atrium venting is performed and ensure adequate drainage. If the lungs are not procured, pulmonary veins can be cut at the pericardial reflection. If the heart and lungs are procured in the donor, left atrium venting can be easily performed by cutting the left atrial appendage. To avoid the left atrial appendage cutting, venting of the left atrium can be done by making an incision in the Waterston's groove or left atrial wall, anterior and medial to the left pulmonary veins at the base of the left atrial appendage. When the heart is empty, an aortic cross-clamp is applied. 1–2 L of cardiac preservation solution is delivered at a pressure of 150 mmHg using a pressure bag. The drainage of the left atrium and IVC is checked to ensure adequate perfusion and the left ventricle is decompressed. Inadequate distribution of organ perfusion may cause irreversible allograft damage [17, 18].

If the lungs are procured in the same donor, cardioplegia is given first and the surgeon must ensure the heart is completely stopped before infusing pulmoplegia to prevent pulmoplegic solutions circulating into the coronary circulation. Topical hypothermia is applied in the chest cavity. After infusion is completed, IVC is completely transected then the left atrial incision is made at the Waterston's groove connecting

the right inferior and superior pulmonary veins. When the heart is lifted, the next incision is made at the left atrium midway between the lower left and right pulmonary veins confluence and the coronary sinus then extended to the left to the base of the left atrial appendage and connected to the right side. Both heart and lung procurement surgeons must agree before incisions are made to avoid anatomical damages and ensure adequate left atrial cuff for the donor lungs. The SVC is transected proximal to the azygous vein to provide adequate length. The ascending aorta is transected at the aortic arch level. The pulmonary artery is divided at the bifurcation level. The heart is then explanted and transferred to the back table to examine for any surgical damages or anatomical anomalies [12, 17, 18].
