Donor Posterior Atrial Flap Rotation for Left Atrial Cuff Reconstruction in Lung Transplantation

Summary

This protocol describes a new method for effectively reconstructing donor atrial cuff anterior wall defects during lung transplantation through the rotation of the donor posterior atrial flap.

Abstract

We describe in detail a novel surgical technique for repairing donor anterior left atrial wall defect in vivo by rotating the posterior atrial flap during lung transplantation. This method can safely and effectively address the most common type of donor left atrial cuff defect: the anterior wall defect, with the intact posterior wall, typically retained when the donor heart is also used. During atrial cuff anastomosis in lung transplantation, the excess donor posterior atrial wall is trimmed into an atrial flap. After the posterior wall anastomosis is completed, the atrial flap is rotated 180° and used as a patch for anterior wall reconstruction anastomosis.

After restoring blood flow, the flow rate of the pulmonary vein is normal and smooth as confirmed by transesophageal echocardiography. Compared with the traditional patch reconstruction method, the new method effectively reduces the atrial cuff anastomosis time. Our results showed no significant difference in pulmonary vein obstruction after reconstruction. Pulmonary artery systolic blood pressure was significantly lower and pulmonary function improved postoperatively in all groups, with no significant differences among the groups. The new technique provides a feasible strategy for the reconstruction of left atrial cuff defects and can improve the effective utilization rate of donor lungs.

Introduction

Lung transplantation, the only effective treatment for most end-stage lung diseases, is limited by a shortage of donor organs. Therefore, it is necessary to optimize the transplant procedure to effectively utilize the potential donor organs¹. The surgical technique for donor lung extraction is an important aspect of this procedure. Currently, it is essential to preserve the intact left atrial cuff, which is routinely used for anastomosis in preference to the pulmonary veins^2,3. Left atrial cuff defect is the most common donor lung injury, occurring in 2.7% of cases upon donor heart and lung separation. Retention of the posterior left atrial wall in heart transplant recipients means that the donor posterior atrial wall tissue is typically fully retained by the donor lung (Figure 1A), making defects of the left atrial cuff anterior wall the most common type of atrial cuff injury (Figure 1B), accounting for approximately 71% of cases⁴. Due to the interatrial groove, anterior atrial wall defect more commonly occurs on the right donor lung^5,6.

This paper introduces a new method of atrial cuff reconstruction that can safely and effectively solve the problem of left atrial cuff defect caused during donor lung acquisition, thereby improving the utilization rate of donor lungs. The key aspect of this new method is the retention of the intact posterior atrial wall of the donor lung. By pruning the excess posterior atrial wall, it forms an atrial flap, and the rotation of the atrial flap provides a patch for the repair of the defective anterior wall.

In cases of atrial cuff defects, extra time is required to shape and reconstruct the atrial cuff to smooth the venous outflow channel and prevent stenosis⁵. The traditional type of patch reconstruction is performed in vitro before the donor lung is placed in the chest, increasing the cold ischemia time. Cuff reconstruction requires the availability of patch material; excess donor pericardial tissue is the most commonly used, although excess arterial tissue can also be utilized^4,5,6. Regardless of the type of patch material used, cuff reconstruction is associated with an increased operation time and an increased risk of surgical complications such as venous outflow tract obstruction caused by non-homologous vascular anastomosis.

The new method can repair the anterior wall defect in vivo by using the excess left atrial tissue of the donor. The operation is more convenient, and the anastomosis time is effectively reduced to reduce the cold ischemia time. This method, which we have named posterior atrial flap rotating left atrial cuff reconstruction, offers a novel and feasible strategy for dealing with anterior atrial wall defect which is the most common type of donor lung atrial cuff defects in lung transplantation.

Protocol

This study was approved by the hospital's ethics review board (approval number ChiCTR2400085507), and written informed consent was obtained from all subjects.

1. Preoperative preparation

1. Confirm the matching information of the donor and recipient.
   NOTE: In our case, confirmation was done by checking the files from the National Organ Transplant Response System.
2. Remove hair from the surgical area and ensure that they have fasted for more than 12 h.
3. Transfer the recipient from the ward to the operating room to await surgery.
4. Ensure that all instruments and materials required for the protocol are available (see Table of Materials).
5. Confirm that donor lungs are available and suitable for use.
   NOTE: All indexes of donor lung, including airway, texture, and laboratory indexes, were up to standard, except for the defect of the anterior atrial sleeve that needed to be repaired.
6. Initiate anesthesia and extracorporeal membrane oxygenation (ECMO) procedures.

2. Anesthesia and ECMO

1. Establish vascular access.
2. Administer intravenous anesthesia. Induce anesthesia by administering 0.05-0.1 mg/kg of Midazolam Injection, 0.1-0.3 mg/kg of Etomidate Injectable Emulsion, 0.8 mg/kg of Rocuronium Bromide Injection, and 0.5-1 µg/kg Remifentanil Hydrochloride Injection intravenously. Maintain anesthesia by administering 5-10 mg∙kg^-1∙h^-1 of Diprivan Injection and 0.5-2 µg∙kg^-1∙h^-1 of Remifentanil Hydrochloride Injection intravenously.
3. Insert double-cavity tracheal intubation and adjust the positions of the left and right openings of the tracheal tube.
4. Insert a SwanGanz catheter through the internal jugular vein.
5. Insert ECMO via the femoral vein and the internal jugular vein.
   NOTE: Depending on the patient's pulmonary artery pressure and heart condition, the surgeon may choose other ECMO modes.

3. Removal of the recipient's diseased lung

1. Position the patient horizontally, with the back slightly elevated and hands spread horizontally in a "cross" position and securely fixed.
2. Disinfect the skin of the surgical area. Use iodophor disinfectant 3x from the inside out. Sterilize up to the neck, down to the umbilicus, and laterally to the posterior axillary line.
3. Ensure that the contralateral lung is ventilated independently, and make a 15-20 cm incision from the fourth intercostal space of the anterior chest wall into the chest without transecting the sternum.
   NOTE: For a double-lung transplant, based on the preoperative assessment, the lung with the more severe condition should be transplanted first. If the severity is similar on both sides, the right lung should be transplanted first.
4. Expose the incision area. Probe the diseased lung and release thoracic adhesions.
5. Release the lower lung ligaments, and free the pulmonary artery and pulmonary vein.
6. Block the proximal end of the right pulmonary artery using pulmonary artery blocking forceps. Sever the upper and lower pulmonary veins using a vascular cutting and closure device. Clamp the distal end of the pulmonary artery and sever the artery.
7. Cut the right main bronchus and surrounding connective tissue at the level of the second branch.
8. Remove the diseased lung and fully control bleeding within the chest.

4. Treatment of recipient's vascular and trachea residuals

1. Cut 1-2 cartilage rings to expose the right main bronchus and trim them flat to ensure complete hemostasis.
2. Prune the recipient's pulmonary artery stump at a distance of 8-10 mm from the blocking clamp.
3. Free the upper and lower pulmonary veins within the pericardium. Ensure that the left atrium at the junction of the upper and lower pulmonary veins can be clamped with atrial forceps.

5. Separation and trimming of donor lung

1. Divide the posterior atrial wall, ensuring that the excess posterior atrial wall is included on the side with the anterior wall defect.
   NOTE: Owing to the position of the interatrial groove, anterior wall defects typically occur on the right side. The excess posterior atrial wall obtained from the right side can provide a source for repairing the short anterior wall (Figure 1B).
2. Sever the left and right pulmonary arteries at the junction of the left and right pulmonary arteries.
3. Free the left main bronchus and sever the bronchus. Separate the left and right donor lungs.
4. Place the left donor lung in an organ preservation solution at 4 °C. Trim the right donor lung. Ensure that the main bronchus has 2-3 cartilage rings. Free the pulmonary artery and atrial cuff fully.

6. Anastomosis of the primary bronchus and pulmonary artery

1. Place the repaired right donor lung into the right chest.
2. Suture the bronchial membrane with a 4-0 PDS line and the bronchial cartilage with a 4-0 poly line. Use a bronchoscope to confirm that the airway is clear and open after bronchial anastomosis is completed.
3. Suture the soft tissue around the bronchial anastomosis with 4-0 poly line and ensure the airway anastomosis is covered.
4. Anastomose the pulmonary artery with a 5-0 poly line continuous suture.

7. Reconstruction and anastomosis of the left atrial cuff

1. Clamp the recipient's left atrium at the proximal end of the intersection of the upper and lower pulmonary veins, ensuring that the junction has 1-2 cm of space for anastomosis.
2. Cut the excess posterior wall of the donor atrial cuff from the bottom upward by comparing the distance between the posterior atrial edge of the donor and recipient. Do not let excess posterior wall break off completely. Trim the excess posterior wall to form an atrial flap, connected to the upper edge of the donor atrial cuff by the pedicle (Figure 2A and Figure 3A).
3. Anastomose the posterior edges of the atrial cuffs from the bottom to the top using a continuous 4-0 Prolene suture (Figure 2B and Figure 3B). Continue the suture (with 4-0 Prolene) upon reaching the posterior atrial flap to anastomose the edge of the atrial flap nearest the lung with the anterior atrial edge of the recipient. Ensure that the suture ends meet at the lower edge of the anastomosis and tie them off (Figure 2C and Figure 3C).
4. Anastomose the other edge of the atrial flap and the anterior atrial edge of the donor from top to bottom with a 4-0 Prolene line continuous suture, and leave the last two needles untightened to serve as exhaust holes (Figure 2D and Figure 3D).

8. Blood flow opening

1. Ventilate and dilate the transplanted lung to fully open the alveoli. Temporarily release the pulmonary artery-blocking forceps, allowing the blood to flow out from the exhaust hole of the atrial anastomosis. Clamp the pulmonary artery with blocking forceps, loosen and remove the atrial forceps, and then tighten the Prolene suture of the atrial sleeve anastomosis after fully exhausting the air.
2. Release and remove the pulmonary artery-blocking forceps to allow full blood flow. Verify that the anterior wall of the anastomosis is wide and well-filled, with no bleeding manifestations.

9. Chest closure

1. Recheck all anastomoses and the chest cavity for bleeding and exudation. Confirm sufficient hemostasis in the chest.
2. Flush the chest cavity, place the drainage tube, ventilate the transplanted lung, and close the chest layer by layer using the chest closure sutures.
3. Excise the contralateral diseased lung and anastomose the donor lung.
   NOTE: The process of excision and anastomosis of the contralateral lung is the same as that for the right, and contralateral left atrial anastomosis is routine due to the intact donor atrial cuff.
4. After bilateral chest closure, monitor and record the flow rate of bilateral pulmonary veins by esophageal ultrasound.

10. Data logging and leaving the OR

1. Adopt a protective lung ventilation strategy to make the transplanted lung fully ventilated, for example, with positive end-expiratory pressure (PEEP) levels of 5-7 cmH₂O and tidal values (VT) of 5-7 mL/kg, while airway pressure peaks < 30 cmH₂O were monitored.
2. Record the pulmonary artery pressure.
3. Insert the esophageal ultrasound probe through the mouth. Monitor and record the flow rate of the bilateral pulmonary veins.
4. Switch to single-cavity tracheal intubation and transfer the patient to ICU for further treatment.

11. Follow-up

1. Measure cardiac and pulmonary artery blood pressures by external cardiac ultrasound 30 days after transplantation, and analyze arterial blood gas routinely. Review lung function and other routine biochemical test results.

12. Statistical analysis

1. Perform statistical analyses and express data as mean ± standard deviation.
   1. Compare groups using analysis of variance, the Kruskal-Wallis test, the Mann-Whitney U test, or the Wilcoxon matched-pairs test. Set statistical significance at P < 0.05.

Discussion

Between 2021 and 2023, the team at the Second Hospital of Zhejiang University/Wuxi Lung Transplant Center performed 931 lung transplants, of which 71 involved donor left atrial cuff reconstruction. To reduce heterogeneity, only 58 double-lung transplants were included in this study. Artificial patches are rarely used in our center, and they were therefore not included in this study.

The anastomosis time of the reconstruction side was significantly shorter in the posterior atrial flap rotating atrial cuff reconstruction group than in the aortic and pericardial patch reconstruction groups, indicating that the new surgical technique effectively shortened the operation time. There was no difference in the anastomosis time of the unrepaired side, which suggests surgical consistency, indicating that the difference in anastomosis time on the repaired side was due to the difference in technique.

Esophageal ultrasonography indicated that there was no significant difference in the velocity of bilateral outlet flow, demonstrating the feasibility of the new approach. Cardiac ultrasonography and patient outcomes also indicated good short-term recovery following the new technique, with no significant differences in short-term complications and adverse reactions compared with the traditional patch reconstruction method. This was further supported by assessments of pulmonary function and arterial blood gases 90 days after transplantation.

To ensure smooth blood flow in the pulmonary vein, the left atrial cuff must be anastomosed during lung transplantation³. During donor lung extraction, ideal cardiopulmonary separation requires preservation of the intact left atrial cuff, including the intact posterior and adequate anterior atrial wall². Atrial cuff defects are common injuries sustained during donor lung extraction³, when the need to utilize both the donor heart and lung often results in competition in some anatomical areas, particularly the left atrial area, which can lead to an atrial cuff defect in the donor lung⁷. Whether donor cardiopulmonary separation should be performed in vivo or in vitro remains controversial.

At present, in vivo cardiopulmonary separation is the preferred technique^2,8. However, in vitro cardiopulmonary separation can better expose the left atrial area, where cardiopulmonary competition may exist⁵. An anterior atrial wall defect of the right-sided donor lung is the most common type of donor atrial cuff defect due to the presence of the interatrial groove⁴. Meticulous dissection and dissociation of the interatrial groove can better expose the left anterior atrial wall on the right side and prevent defects in the atrial cuff of the right donor lung³.

When atrial cuff defects occur, intraoperative anastomosis becomes more difficult, and it is often necessary to shape and reconstruct the atrial cuff to prevent bleeding and related venous outflow channel complications, which increases the cold ischemia time. Studies have shown that although prolonged cold ischemia time due to increased anastomotic duration has no effect on long-term survival, it can affect survival at 90 days postoperatively and increase the risk of airway complications⁹. Defects in the atrial cuff also cause donors to be downgraded from ideal to marginal¹⁰.

When atrial cuff defects occur, forced anastomosis with tension or separate anastomosis of the upper and lower pulmonary veins increases the risk of venous outflow channel obstruction¹¹. Instead, a slightly more compact posterior atrial anastomosis and looser, tension-free anterior anastomosis can open the left atrial outflow channel. Hammond et al.⁵ introduced the use of pericardial tissue adjacent to the pulmonary vein for reconstruction, resulting in a wide and smooth atrial cuff anastomosis and a bilateral perfusion flow rate matching the recipient. It has been argued that direct anastomosis of the peripheral pericardium without reinforcing the pulmonary vein stump to the pericardium can reduce the risk of blocking or narrowing the vein opening¹². The availability of pericardial tissue and its good outcomes make it the most important material for atrial cuff patch reconstruction. Sugimoto et al.⁶ reported a method of using excess donor pulmonary artery to reconstruct atrial cuffs, with good surgical outcomes. However, there have been no reports on the use of the surplus posterior left atrial wall of the donor lung to reconstruct anterior wall defects.

Here, we introduce this new reconstruction method for the donor atrial cuff, named the posterior atrial flap rotating left atrial cuff reconstruction technique, and compared and analyzed its safety. In terms of surgery, the posterior atrial flap rotating left atrial cuff reconstruction method is more convenient and rapid, as it does not require in vitro atrial cuff formation but can be repaired directly during anastomosis. Moreover, because the reconstructed area is made from the same atrial tissue, tissue compatibility is good, and there is maximal preservation of the blood supply to the repaired area. Regarding prognosis, the posterior atrial flap method can keep the anterior atrial cuff loose after anastomosis and reduce the occurrence of complications related to venous outflow, bleeding, and re-reconstruction compared with patch reconstruction methods, as well as decrease the cold ischemia time through a faster anastomosis. This simple surgical method provides a feasible strategy for the reconstruction of atrial cuff defects in the donor pulmonary vein, with good clinical outcomes.

This study has certain limitations. For example, the statistical difference in the ratio of male to female recipients among the three groups and the inability to maintain the same quality of donor lungs due to the complexity of lung transplantation may have affected the results of the study. This method is only applicable to the most common type of atrial cuff defect, the anterior atrial wall defect, and requires an intact posterior atrial wall. If the posterior atrial wall is incomplete, patch reconstruction or other formation methods are required.

In conclusion, this study describes a new method of donor lung left atrial cuff reconstruction. This new method can effectively address atrial cuff anterior wall defects during lung transplantation by rotating the posterior atrial flap. Although no significant differences were observed in complication rates and venous obstruction in the short term between the posterior atrial flap and patch reconstruction methods, use of the posterior atrial flap method effectively reduced the atrial cuff anastomosis time. Compared with the traditional patch reconstruction method, it also reduces the difficulty of the operation and has the potential to reduce the risk of long-term complications such as anastomotic ischemia and mural thrombosis. This technique therefore provides a feasible strategy for atrial cuff defect reconstruction and may improve the effective utilization rate of donor lungs.

Materials

Name	Company	Catalog Number	Comments
ACE+7 SHEARS	ETHICON	HARH23
Articulating Endoscopic Linear Cutter	ETHICON	PSEE45A
Atraumatic tissue forceps	Delacroix-Chevalier	DC13200-24/DC13200-20
Atrial blocjing forceps	Delacroix-Chevalier	DC40672-26/DC40673-26
Blue monofilament non-absortable suture (4-0)	ETHICON	REF8521
Blue monofilament non-absortable suture (5-0)	ETHICON	HS6856
Bronchoscope	OLYMPUS	BF-Q170
Coated vicryl plus antibacterial suture (1-0)	ETHICON	VCP359
Diagnostic Ultrasound System	PHILIPS	EPIQ 7C
Diprivan Injection	AstraZeneca	1%w/v
Disposable Skin Stapler	Pride	P-PF-35R
ECMO	Maquet	CARDIOHELP-i
Electrosurgical Pencil	AESCULAP	GN300
Needle Holder	Delacroix-Chevalier	DC51170-24/G30154
Negative pressure suction device	SMAF	YX930
PDS II absorbable suture (4-0)	ETHICON	W9109
Pulmonary artery blocking forceps	Delacroix-Chevalier	DC13010-23/DC13010-23
Remifentanil Hydrochloride Injection	CNPIC	H20223422
Thoratrak MICS Retractor System	Medtronic	28605
Tissue scissors	Delacroix-Chevalier	B25925