Authors report a new method of cardiac sampling for transplantation from donors deceased after circulatory stop, which avoids the drawbacks of the two existing techniques.
Cardiac allografts from donors deceased after circulatory stop (that is to say the so-called DCD cardiac allografts [donation after circulatory death]) are generally obtained either by direct debit and infusion, or by normothermal regional infusion.
Limits of current sampling techniques: ethical questions and costs
The direct direct debit technique requires devices from the situation complexes, presents an increased risk of dysfunction of the primary graft and does not ensure the resuscitation of the abdominal organs.
This is why many teams use the normothermal regional infusion which increases organ efficiency and gives better results in the transplants of cardiac and abdominal organs. However, this last technique is the subject of an ethical controversy and many hospitals and countries prohibit it for two reasons: it requires the resuscitation of the heart of the donor, which denies the definition of circulatory death, and it implies the clamping of the vessels of the aortic butt to prevent the brain infusion, which, according to some, creates the possibility of a brain infusion.
Given these limits, authors have developed another method called REUP (rapid recovery with prolonged ultra-oxygenated preservation), described in an article recently published in the New England Journal of Medicinewith the results obtained from the first three receivers of hearts taken using this method.
A prolonged and ultra-oxygenated rinse of the heart
A rinsing circuit consisting of a standard normothermal regional infusion circuit with an additional tank and a heating and cooling device has been built. Before stopping living care care, the extracorporel circuit is started with 2 globular butt units, 500 cc of plasalyte crystalloid solution and 2 liters of Nido cardioplegia solution (13 mmol of bicarbonate per liter). Also added heparin (30,000 units), mannitol (3,125 mg), rocuronium (50 mg), solumedrol (125 mg), ciprofloxacin (50 mg), cefazoline (250 mg), N-acetyl-l-cysteine (30 g), albumin at 25 % (50 ml) Multivitamin and levothyroxine (50 µg). After mixing components, the conservation solution is oxygenated by the extracorporel circuit and a scanning gas with a flow rate of 2 liters per minute and an inspired oxygen fraction (FIO2) of 100 % are maintained for 5 minutes. Samples have been taken to analyze gases of arterial blood and bicarbonate has been added if necessary to reach a pH of 7.5, a bicarbonate level of 30 mmol per liter and a partial oxygen pressure greater than 500 mm Hg. Heating and the cooler ensured a rinsing temperature of 4 ° C.
The final declaration of death was made after a 5 -minute waiting period. A sternotomy has been practiced and the left and right hearts were broken down by incisions in the straight pulmonary veins or in the inter-earrecal groove and in the lower cellar. A CLAMP was placed on the ascending aorta in the same way as during a standard sample, which eliminates any possibility of systemic or cerebral infusion. A bifurcated cardioplegia from the aortic root has been placed near the Clamp, and the root was manually disseminated. A rinsing line was placed on a branch of the root needle and a pressure line was placed on the other. The authors administered 2 liters of oxygenated rinsing extended through the aortic-root needle to an average pressure of 80 mm Hg at the root of the aorta. This corresponded to a flow of around 200 ml per minute and therefore required about 10 to 12 minutes. During rinsing, a 10 ° C saline solution was placed on the heart. A donor cardiectomy was then standard and the heart was placed in a 10 ° C cooler for transport. The time elapsed between the first declaration of death and the rinsing was 8 to 10 minutes.
Other organs have been taken, including the lungs, the liver, the pancreas and the kidneys. The abdominal bodies have been recovered by direct debit and infusion or rapid recovery from two of the donors and by abdominal normothermal infusion in the third donor.
The first three transplants
In the first three cases reported in which this method was used, hearts have been successfully transplanted, with a normal biventricular function, no sign of rejection, and excellent early postoperative results. No adverse events were reported in perioperative period.
The receivers have undergone a sternotomy with aortic and bicaval central venous cannulation. After the implementation of a cardiopulmonary bridge, a recipient cardiotomy was practiced. The heart of the donor was inspected to verify that the valve structures were normal. The anastomoses of the donor’s heart were then made in the following order: left atrium, lower vein, pulmonary artery and aorta. After the anastomosis of the aorta, the aortic clamping was removed and the anastomosis of the upper vein was carried out during the reperfusion of the heart. After reperfusion, patients were weaned with cardiopulmonary bridging. Peroperative echocardiography has shown normal bivertricular function in receivers 1 and 2 and normal left ventricular function and slightly reduced right ventricular function in recipient 3. Epicardial stimulation threads and mediastinal and pleural thoracic tubes have been put in place, and thorax has been closed.
Promising postoperative results
After the intervention, the three recipients presented no complications. The cardiac index of recipients varied from 2.8 to 4.4 liters per minute and per square meter during the first postoperative week, and the receivers were weaned in the infusions of inotroped to 7e day. Postoperative echocardiography has revealed a normal biventricular function.
Receiver 1 (grafted heart and kidney) received a temporary continuous renal substitution therapy followed by intermittent hemodialysis, but he then completely restored renal level.
All patients have received standard immunosuppressive treatment including prednisone, mycophenolate mofetil and tacrolimus. Receivers had a normal biventricular function and had no signs of cellular cell rejection or mediated by antibodies six months after cardiac transplantation.
By avoiding the limits of infusion platforms from the situation As well as the controversial aspects of the regional normothermal thoraco-abdominal infusion, this method of heart recovery is promising but other studies are necessary to validate it. Currently, the reducing technique is applicable to well -selected donors (aged 18 to 40) whose cold ischemia time is acceptable (≤ 4 hours).
