While the heart is taken for transplant, simultaneously the lungs are supplied as either double lungs, single or two single lungs. This means that if a surgeon does not take both for two separate patients in the same center, both the heart surgeon and lung surgeon will be there. For the supply of thoracic organs, a maximum of three different surgeons can be found, assuming that each of the two lungs is taken by different centers and the heart is taken by another center. To successfully implement such a multi-organ procedure, it requires the highest level of cooperation and communication with each other. The cardiac surgeon starts first and examines the heart, the sternotomy is done in the midline after logging in and basic checks, when all teams are ready. Hemostasis is achieved using a large amount of bone wax and the pericardium is divided in half.
Three pericardial support sutures are placed on either side of the pericardial opening and labeled on hemostats. According to practice, it is recommended not to attach pericardial support sutures to drapes at this point. This is because it causes tension in the pericardium and causes hemodynamic impairment by compressing the heart while the lung surgeon tries to examine and extract the lungs with a Valsalva maneuver. Once the heart is properly visualized, to assess atherosclerosis, the coronary arteries are palpated, the contraction of the heart is visually confirmed, and the condition of the heart is checked by checking the right atrium, right ventricle, pulmonary artery and aorta. It is also important to check for any palpable excitement or any abnormalities in systemic venous drainage or pulmonary venous drainage. Intracardiac pressures should be measured according to surgeons practice, pulmonary artery (PA), right atrial (RA) and left atrial (LA), and the surgeon who implanted them should be contacted for cross-checking, it is also important that the pleura is not opened and this is when the lung surgeon becomes the focus of attention. .
When it comes to the lung surgeon, the pleura should be opened wide and it is often recommended to open the pleura sharply rather than using diathermy. Because there are many examples where opening the pleura with diathermy causes air leakage as it accidentally pierces the lung surface. After part of the pleura is opened bluntly, a finger can be inserted into the back of the pleura but only above the lung tissue. It is used safely with the finger protecting the lung to divide the rest of the pleura in a standard way. At this stage, the lungs and atelectatic areas are examined and the lung is prepared for Valsalva. The lung surgeon, after discussing this with the anesthesiologist, reaches the lower lobe, where it is important to make the earlier point of leaving the pericardial stay sutures without anchors.
If they are stuck and applied valsalva, the heart is squeezed between the stuck pericardium and the lungs, causing a sudden drop in blood pressure. For this reason, the pericardial support sutures are left unattached and the pleura is cut wide, allowing the heart to have more room for movement. Permanent sutures can be placed on both sides after checking the compliance and determining the condition of the lung by examining whether there is any abnormality such as a mass or contusion. Pulmonary vein blood gases are taken from the upper right, lower right, depending on the institution’s protocol, and the supply then continues in a standard fashion. First, the aorta and pulmonary artery are cut, then an umbilical band is used to rotate the aorta while separating the SVC from the pulmonary artery. Then the superior vena cava (SVC) is looped and the azygous vein is ligated. The azygos vein is fragile and can be easily injured causing rapid bleeding that is difficult to manage. It is generally preferred not to cut the IVC (inferior vena cava) or interatrial groove before heparin is given, so that it is possible to avoid hemodynamic compromise and rhythm disturbances such as atrial fibrillation. For this reason, the internal defibrillation paddles on the sterile table must be open and ready to use at all times during procurement.
The standard dose of heparin – 30,000 units is then given and adjusted according to the patient’s weight. The cardioplegia stitches are then removed and the aorta cannulated. A double lumen cardioplegia cannula is recommended and the pressure line is transduced to monitor the patient’s aortic root pressure. Because this cardioplegia helps in reporting the perfusion pressure. When the cardiac surgeon cannulate the aorta, the lung surgeon inserts the pouch string into the pulmonary artery (PA). At this point, surgeons must decide where to divide the Pulmonary artery. On the one hand, it is desirable for the cardiac surgeon to remain at a sufficient length, so it is important not to cut it too short. On the other hand, he may wish to leave the bifurcation of the PA intact for the lung surgeon. For this reason, a guide is usually used to correct pulmonary arteries and the purse string is placed at that level. After the purse string suture is in place, it is generally recommended to use a right angle cannula and direct the cannula bevel towards the pulmonary valve. This is to prevent improper perfusion of pulmonary arterial flushing.
Usually, those with some new surgeons do everything right except to turn the cannula’s slope toward the left pa. However, this results in preferential flow to the left lung with minimal flow to the right lung, resulting in poor perfusion with improper preservation of the right lung. It is still important to ensure adequate distribution of pulmoplegia if a different type of cannula is used. When all teams are ready, the cardiac surgeon clamps the aorta and the lung surgeon applies the prostaglandin. The injection site should be as close as possible to the purse string suture on the PA to prevent additional puncture of that artery. Since prostaglandin causes blood pressure to drop, this is the time when all teams must be extremely vigilant. Next, the SVC is captured and the left atrial limb is divided by placing a Satinsky clamp on it, and the tip is cut off.
When placing the clamp, it is important not to apply traction to the left arterial extension to avoid damage to the appendix or the base of the left circumflex artery. For this reason, some surgeons oppose the idea of placing a clamp in the left arterial extension. However, if they are venting through the interatrial groove, then this should be done before dividing the IVC. The next step is to split the anterior wall of the IVC, and after this is done, approximately 3-4 hits should be expected. While the heart is discharging, one should be patient and the aorta of the flaccid heart should be cross-clamped as distally to the arch vessels and infusion of cardioplegia solution should be initiated. It should be noted that the lung team can initiate the perfadex solution, not until it is realized that the heart is completely arrested, so care should be taken not to initiate these at the same time. Meanwhile, the surgeon must feel the left ventricle by touching the left ventricle continuously to ensure that it is soft and the aorta is intact.
Note that when the pulmoplegia is perfused into the PA, outflow from the left atrial limb should be seen. The color of the lungs should continue to be monitored to look for uniform bleaching that indicates an even distribution of the wash solution while simultaneously reducing the FIO2 to 50% while the lungs continue to ventilate. During this procedure, manipulation of the heart should be avoided. If the left ventricle (LV) is stretched for any reason, cardioplegia and pulmoplegia should be stopped, the cross clamp on the aorta released, and the heart slowly relaxed. Then, by applying the cross clamp again, cardioplegia and pulmoplegia should be continued. Also, if the tension continues, the LA extension should be opened further. But if this still does not work, the interatrial groove should be used for ventilation. This procedure usually gives about 4-6 liters of perfadex solution, but this may vary according to hospital protocol.
If perfadex is working, the cardioplegia should be kept running, and this ensures that perfadex does not enter the coronary and clear the cardioplegia. If cardioplegia is performed prior to pulmoplegia, aortotomy should be performed while the clamp is still there, and a yonkaeur absorber placed in the aorta to suck and prevent any perfadex solution from entering the heart. After all flushing has been done for both the heart and lung, the pulmonary artery cannula is removed and the prolene suture cut. The IVC is then divided completely, taking care to avoid any injury to the right lower pulmonary vein. The next step is to optimally divide the left atrium. The recommended approach is to gently pull the heart up while cutting the posterior LA wall, using a metzenbaum scissors to enlarge the incision, leaving a sufficient LA cuff for the lungs for at least 1 cm margin.
On the right, the dissection should be stopped when the IVC is reached and at this point the heart should be retracted to the left. With the drooping heart and bloodless area, it should be easier to examine the interatrial groove and at least one centimeter should be left for the lung implant. Finally, depending on how much aorta is needed, the aorta can be transected as high as possible. For PA, the incision should be extended from where it was cannulated and the hull of the PA should be visualized, making sure that the opening of the right PA is visible. The PA bifurcation must then be split so that it remains with the lung block, and too much traction should not be used when splitting, as this may cause distortion. However, it should be ensured that the original incision is upright, leaving enough PA for the cardiac team. When all the compartments are complete, the clip in the SVC is released, the SVC, the azygos vein and everything else holding back should be split while the heart is gently lifted. After these processes are completed, the lungs are then collected in a standard way. It is always helpful to have a nasogastric tube so that it can feel the esophagus.
The arch veins and the innominate artery divide, at which point the trachea is exposed and looped, then the trachea is stapled at 60% tidal volume. The lungs are then taken to the back table and 250 cc of retrograde flushes are given from each pulmonary vein. There are different ways to perform a retrograde wash effectively. Some do this in place on the chest, others take the lung block to the back table. It is generally preferred to take it to the back table and to apply 250 cc perfadex per vein. One technique is a catheter with an inflated bulb at the end and is inserted into each vein in turn as the flush is applied. The caveat about this is that you may injure the pulmonary vein ostium (the delicate one) by unintentionally over-inflating. The other technique is Dr. Hassan Nemeh’s personal communication is to use a retrograde cardioplegia catheter with a self-inflating balloon, so it is much safer and less traumatic. The only problem with this is that it is not part of the standard kit, so purchasing surgeons should not forget to bring it with them.
Yet another technique that can be used is to use the rubber tube at the end of the tube. The tube is inserted into the pulmonary vein and then the vein is tightened to create a tight seal. Whichever technique is used, it should be noted that it is important that the perfadex solution is only 30 cm above the table and that it is operated by gravity, and excessive pressure that may cause pulmonary edema should be avoided. When perfusing retrograde, it should be ensured that there is any clot in the pulmonary artery. It is not uncommon to have a minor embolism. No matter how large clots are visible, a retrograde wash should be left at the implantation center, or it is important to alert the implant surgeon who may choose to repeat. Some teams use Ex-Vivo Lung Perfusion (EVLP) in such cases. After completion of the retrograde wash, look inside the PA to assess whether there is any remaining clot.
Writer: Ozlem Guvenc Agaoglu