Enbloc Heart and Lung Transplantation – A Case Report

Introduction

Heart-lung transplant is the ultimate option available for patients who suffer with both advanced irreversible heart dysfunction and terminal lung disease. The term ENBLOC refers to the harvest and implant of heart and lungs together rather separately. Here, we report a case of successful transplant of both heart and lungs. Heart and lung transplantation is a suitable treatment for selected patients with end stage chronic lung disease.¹

Case Presentation

The recipient was an old man aged 68 years suffering from terminal illness of interstitial lung disease and coronary artery disease with severe LV dysfunction. He was on optimal medical therapy and had Class IV dyspnoea on oxygen mask support. His body weight was 62 kg with B Positive blood group.

Donor Details

The donor was 24 year old patient in comatose state following a road traffic accident. He was weighing 80 kg with O Negative blood group. The blood serology for HIV, HCV and HBsAg was negative. The oxygen challenge at 100% FiO₂ offered a PaO₂ of 545 mm of Hg. He was on mild support of vasopressors. The donor specific antibody test was done and it turned to be negative. The human leukocyte antigen typing between the donor and the recipient was a 3/6 locus match. An induction dose of Basiliximab was given to the donor. The use of induction therapy with Basiliximab in lung transplant patients reduces the incidence of acute rejection in the first month after transplant, with no differences in positive Broncho Alveolar Lavage (BAL) cultures.²

Organ preservation

The gold standard preservation solution for heart is the custodial HTK (Histidine, Tryptophan & Ketoglutarate) solution and for the lungs, it is the Perfadex plus solution. The custodial inactivates organ function by withdrawal of extracellular sodium and calcium, together with intense buffering of the extracellular space, and prolongs the ischemic period. The Perfadex plus is an extracellular, low potassium, dextran-based electrolyte preservation solution for rapid cooling, perfusion and cold static storage of donor lungs – pre supplemented with calcium ions and THAM (Tris Hydroxy Methyl Amino Methane). Pulmonary artery flush cooling was achieved by infusing 50 mL/kg 4°C Perfadex solution through a 24F cannula.³

Organ preservation technique

The donor organ preservation is one of the key aspects that determines the outcome of the surgery especially in tackling primary graft dysfunction. We cannulated the aorta with a 14 G cardioplegia cannula and the pulmonary artery with 24 Fr cannula. A bolus of 500 µg prostaglandin was administered in the PA which induced a bradycardia and mild hypotension. The aorta was cross clamped and simultaneously 2 litre custodial solution was given in aorta with help of a pressurized bag from the anesthesia end and 3 litre Perfadex plus was given in the pulmonary artery by gravity. The return solution was sucked out from the nicks made in the left atrium and right atrium. The trachea was clipped using 4’0 Endo GIA Stapler with subtly inflated lungs. The Enbloc was harvested and immersed in 6 litres cold normal saline solution bag. The whole graft along with the 6 litres NS solution was packaged in a sterile bag which was surrounded by two additional packs with lots of ice slush.

Considerations of Heart and Lung Donor Criteria⁴

 Age <55 years

 Clear chest X-ray

 Oxygen Challenge: PaO₂ > 100 mm Hg on 40% FiO₂ ; PaO₂ > 300 mm Hg on 100%

 Absence of chest trauma

 Absence of microbiologic endobronchial organisms

 Absence of malignancy

 Absence of purulent secretions or signs of endobronchial aspiration

 ABO compatibility  Size matching

 No history of chest trauma or cardiac disease

 Appropriate hemodynamics: MAP > 60; CVP - 8 to 12 mm Hg

 Inotropic support < 10 µ/kg/min (Dopamine or Dobutamine)

 Normal ECG/ Normal ECHO

 Negative serology (HBsAg, HCV and HIV)

Operative strategies

The approach was through median sternotomy and CPB (Cardio Pulmonary Bypass) was instituted after systemic Heparinization and with standard aortic and bicaval venous drainage. The recipient was cooled to 28˚C and cardioplegia was administered after cross clamping the aorta. The heart and lungs were excised and the trachea was excised just below the carina. The vascular bed around the carina was well preserved. Meticulous care was given to preserve the innervation especially the recurrent laryngeal nerve, vagus nerve and the phrenic nerve. Preservation of the nerves is often more difficult than in isolated heart or lung removal because of the extensive mediastinal dissection required in heart-lung transplantation, but failure to do so results in profound postoperative respiratory insufficiency, vocal cord paralysis, or gastrointestinal dysfunction.⁵ The Enbloc organ was placed inside the chest cavity correctly and the anastomosis of trachea was performed with 4’0 PDS (Poly Dioxanone Suture) continuously for the posterior aspect of membranous tracheal tissue and interruptedly in the anterior aspect of the cartilaginous tissue. The sequence of anastomosis after the trachea were aorta, IVC and the SVC respectively. The lungs were cautiously inflated and ventilated to prevent any occurrence of lobar atelectasis. Bronchoscopy was carried out to check if the tracheal anastomosis was patent, and the airways were clear of secretions.⁵ The lungs were ventilated with 21% air and slowly the oxygen was exposed into the new lungs. After effective deairing the aortic cross clamp was removed. Hemostasis was done meticulously during the CPB. After rewarming, patient was weaned off from CPB gradually.

Perfusion strategies

Aortic cannula was 22 Fr Medtronic, 24 Fr and 28 Fr Right angled cannula Medtronic for SVC & IVC respectively. Inspire 6 Phosphoryl Choline Coated oxygenator was used. Pump flows were maintained > 2.2 L/min/m² with MAP (Mean Arterial Pressure) > 60 mm of Hg. The cold ischemic period and the warm ischemic period were 144 and 75 minutes. Albumin and tranexamic acid were continuously on flow. Continuous Zero Balanced Ultra Filtration (ZBUF) was carried out throughout the bypass to keep the inflammatory mediators and lactate levels in check. ZBUF was used during CPB not as a hemoconcentrating measure but as a means to reduce circulating elements generated most often through inflammatory processes or electrolyte imbalances created by cardioplegic solutions. We used Plasmalyte A & normal saline as replacement fluids during ZBUF. Two units of irradiated red blood cells were used; the hematocrit while coming off was 32%. Total CPB time was 250 minutes. Cell saver was also used to effectively conserve the red blood cells to minimize the transfusion.

Post-operative course

Inhalational nitric oxide was used in the immediate postoperative period to counter rise in pulmonary artery crisis. On the 3^rd post-operative day, the right lung was downsized in the basal area as it was crumpled. In the presence of a moderate-size discrepancy, peripheral non-anatomical resections using stapler devices were performed after implantation and full inflation of the lung.⁶ Chest was closed properly in the 4^th postoperative day. Periodic bronchoscopies (once in two days) were carried out to let out the bronchial secretions. Total ventilation hours were 124 hours. Regular chest physiotherapy was done. Patient was put on triple regimen of immunosuppressants- Tacrolimus, Mycophenolic acid and Prednisolone. The endomyocardial biopsy and the lung biopsy showed no signs of acute rejection. Endo myocardial biopsy for the heart and transbronchial biopsy for the lungs remains the “gold standard” and is a widely accepted practice for the diagnosis of rejection in heart and lung transplant recipients.⁷ Total hospital stay was 24 days. The patient is on regular follow-up (every 6 months) and continues the immunosuppressant therapy.

Discussion

One of the key factors to success in this case was the selection of suitable donor and appropriate recipient. The donor specific antibody test between the donor and the recipient was negative and the Human Leukocyte Antigen (HLA) typing between the donor and the recipient was 3/6 locus match. The successful outcome of solid organ transplantation today is severely impeded by the production of alloantibodies, mainly directed against the protein products of HLA complex of the organ donor.⁸

The impeccable care during organ harvesting and organ protection holds a significant part in determining the outcome of the surgery. The lesser the ischemic time the better the chance of not developing primary graft dysfunction. The cold ischemic period i.e., from the time the organ is given the preservation solution till it is taken out from the cold storage unit and the warm ischemic period i.e., from the time the organ is taken out from the cold storage unit till it is reperfused are crucial for these types of surgeries. Long-term graft survival in heart transplantation patients with older donor allografts may improve when cold ischemic time is shorter.⁹

Pump flows were maintained > 2.2 L/min/m2 with mean arterial pressure > 60 mm of Hg. The perfusion was optimized to maintain good adequacy of perfusion throughout the run. The serum lactate during the CPB was < 4 mmol/L. The mixed venous saturation was maintained > 70%. Serial ABGs showed no signs of acidosis. Meticulous haemostasis and utmost care to the innervation were some of the salient features of this complex surgery. The need of post-operative ECMO (Extra Corporeal Membrane Oxygenation) is quite possible in this type of surgery and the ECMO disposables, hardware and the team should be available as a 24/7 back up in case if the primary graft dysfunction ensues. Christian A. Bermudez et al., suggests that long-term survival of patients with primary graft dysfunction (PGD) requiring ECMO (overall and weaned) was inferior to that of patients who were not on ECMO for PGD.¹⁰

The post-operative care is crucial in these surgeries. Cardio pulmonary rehabilitation is important to cough out the secretions effectively since the cough reflux would be poor in these patients. These subsets of patients are to be provided with extreme care of aseptic measures while handling to avoid any infections.

Enbloc heart and lung transplant is a high-profile surgery offered for patients suffering from end stage heart and lung failure that requires multiple strategies in preoperative, intra-operative and post-operative periods. A holistic cohesive teamwork of the multi-disciplinary team helped in the speedy recovery of patient.

Conflicts of interest

None