Ann Thorac Surg 2006;81:360-362
© 2006 The Society of Thoracic Surgeons
Case report
Pulmonary Artery Dissection Complicating Lung Transplantation for Primary Pulmonary Hypertension
Yasushi Sakamaki, MD,
Masato Minami, MD,
Mitsunori Ohta, MD,
Toshiki Takahashi, MD,
Goro Matsumiya, MD,
Shinichiro Miyoshi, MD,
Hikaru Matsuda, MD
*
Department of Surgery, Course of Interventional Medicine E1, Osaka University Graduate School of Medicine, Osaka, Japan
Accepted for publication August 13, 2004.
* Address correspondence to Dr Matsuda, Department of Surgery, Course of Interventional Medicine E1, Osaka University Graduate School of Medicine, Yamadaoka 2-2, Suita, 565-0871 Japan (Email: matsuda{at}surg1.med.osaka-u.ac.jp).
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Abstract
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We report a case of pulmonary artery (PA) dissection complicating lung transplantation. A 30-year-old man with primary pulmonary hypertension underwent bilateral single lung transplantation. Thirty hours postoperatively he had signs of obstruction of the right main pulmonary artery develop due to dissection demonstrated on transesophageal echocardiography and pulmonary arteriography. Surgical repair of the dissection with reanastomosis of the pulmonary artery was successfully carried out, and the patient subsequently improved to a favorable condition. Pulmonary hypertension is a risk factor of pulmonary artery dissection; our case suggested that underlying chronic pulmonary hypertension might have led to this rare and life-threatening anastomotic problem after lung transplantation.
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Introduction
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Pulmonary artery (PA) dissection is a rare condition that occurs most often in patients with underlying pulmonary hypertension (PH) [1, 2]. We treated a patient with primary PH who had a unilateral PA dissection develop immediately after bilateral lung transplantation.
A 30-year-old man underwent bilateral lung transplantation (LTx) for end-stage primary PH. The lung allografts were retrieved from a brain-dead donor, transplanted in a sequential manner under cardiopulmonary bypass (CPB), and reperfused after approximately 7 hours of ischemia. The patient was transported to the intensive care unit in favorable condition with excellent gas exchange and hemodynamic stability that was maintained in the first 30 hours after surgery. However, after this period his condition gradually deteriorated with abnormally elevated PA pressure (> 40 mm Hg, mean) and poor gas exchange (arterial carbon dioxide, > 80 mm Hg). Transesophageal echocardiography then demonstrated obstruction of the right main PA immediately proximal to the anastomosis, owing to a thrombus-like lesion plugging almost the entire vascular lumen (Fig 1A). Pulmonary arteriography confirmed severe stenosis of the right main PA near the anastomosis with diminished blood flow, but ruled out multiple defects in the PA images (Fig 1B). These findings suggested PA dissection rather than pulmonary thromboembolism, and the patient then underwent an emergency operation for reconstruction of the narrowed PA segment under cardiopulmonary bypass. Although the PA anastomosis at the time of the LTx was made difficult by the caliber-size mismatch between the donor and the recipient, the cut-end of the recipient's right PA that had been stapled was partially opened by excising four-fifths of the length of the stump, which was then anastomosed to the donor PA with 5-0 polypropylene sutures. Removing this anastomosis revealed a protrusion that appeared to arise in the subintimal layer of the recipient's native right PA (Fig 2). Through an incision made on the protruding intima, the underlying fresh thrombi were removed. We then applied gelatin-resorcin-formalin glue beneath the dissecting layer with a Foley balloon catheter plugging the PA at the bifurcation level to prevent glue draining into the proximal lumen. We also pressed the glued layer of the PA wall with the inflated balloon to secure closure of the false lumen before suturing the intimal incision. Although the entry site in the right PA could not be identified, repair of the dissection was successfully carried out. Blood was scarcely sucked from the false lumen while effluent blood flow was continuously observed from the true lumen proximal to the dissecting area, which allowed us to assume that the dissection might have been developed in a retrograde manner starting from the anastomosis. Refashioning the anastomosis necessitated removal of the remaining staples and rebuilding of the PA stump with a native pericardial patch. The patient subsequently made an excellent recovery and was discharged from the hospital on posttransplant day 60. No disease signs, such as infection, rejection, or other surgical complications have been detected in the 37 months after the LTx.
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Fig 1. (A) Stenosis of the right main pulmonary artery on transesophageal echocardiography. The blood flow overriding the aorta (Ao) represents the flow between the main and right pulmonary arteries (mPA and rPA, respectively), and is attenuated due to a thrombus-like lesion in the false lumen (arrowheads). Note an intimal flap shown in the dissecting PA (arrow). (B) Stenosis of right main pulmonary artery confirmed by pulmonary arteriography. Narrowed segment is evident in the proximal right pulmonary artery (arrowheads).
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Comment
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Pulmonary artery stenosis due to dissection has hardly been recognized as a vascular complication of LTx, as far as we could ascertain from a Medline survey of the English literature. To date, we found only one major series that had previously reviewed pulmonary vascular complications after LTx [3]. Pulmonary artery dissection causing stricture near the anastomosis may be extremely rare in LTx. However, it is noteworthy that posttransplant PA dissection can occur in lung recipients with primary PH and progress rapidly to a critical problem in which an emergency operation should be indicated.
The underlying mechanisms for PH patients who require PA dissection immediately after LTx remain to be clarified. Pulmonary artery obstruction may occur due to pseudoaneurysms, with Swan-Ganz catheter-induced injury representing a major cause [4]. However, no iatrogenic causes were evident during the anesthesia or throughout the postoperative intensive care in our case. In the majority of patients with PA dissection in whom detailed histologic features were available, medial degeneration or necrosis were often observed and considered secondary to coexisting PH [2]. Histologic examination limited to the resected lungs failed to demonstrate medial degeneration or necrosis in our case.
Latent traumatic events during the LTx might have contributed to the initiation of intimal tearing of the recipient's PA, which in turn might have been far more susceptible than usual due to primary PH. We assume that applying a vascular stapler to divide the PA in pneumonectomy or other maneuvers neglecting precaution against susceptibility of the diseased PA wall might have triggered the PA dissection, unless the occurrence was catheter-induced or spontaneous. Therefore, repair of the dissection appeared to necessitate a specific technique to avoid re-stenosis of the PA anastomosis due to surgery-induced injury. Our technique using gelatin-resorcin-formalin glue and a Foley catheter was effective in preventing PA dissection from recurring and seemed minimally invasive. However, evident involvement of the bifurcation would have necessitated thorough exploration of the PA by an approach through the central PA to achieve a certain control of the situation.
Some studies have reported that pulmonary vascular complications of the LTx remain a source of considerable morbidity and carry a high mortality; therefore the immediate need for identification of a pulmonary vascular obstruction after LTx cannot be overemphasized [3, 5]. Transesophageal echocardiography routinely used during intensive care unit stay, mostly within several days of LTx, provides an accurate guide to the morphologic and functional state of the pulmonary vascular anastomoses and contributes to immediate diagnosis of stenosis in the main PA, as seen in our case [5, 6].
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Acknowledgments
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We wish to thank Dr Hajime Matsue (Osaka University) for help in preparing the figures of transesophageal echocardiography.
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References
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- Stern EJ, Graham C, Gamsu G, Golden JA, Higgins CB. Pulmonary artery dissectionMR findings. J Comput Assist Tomogr 1992;16:481-483.[Medline]
- Inayama Y, Nakatani Y, Kitamura H. Pulmonary artery dissection in patients without underlying pulmonary hypertension Histopathology 2001;38:435-442.[Medline]
- Griffith BP, Magee MJ, Gonzalez IF, et al. Anastomotic pitfalls in lung transplantation J Thorac Cardiovasc Surg 1994;107:743-753.[Abstract/Free Full Text]
- DeLima LGR, Wynands JE, Bourke ME, Walley VM. Catheter-induced pulmonary artery false aneurysm and rupturecase report and review. J Cardiothorac Vasc Anesth 1994;8:70-75.[Medline]
- Clark SC, Levine AJ, Hasan A, Hilton CJ, Forty J, Dark JH. Vascular complications of lung transplantation Ann Thorac Surg 1996;61:1079-1082.[Medline]
- Boyd SYN, Sako EY, Trinkle JK, O'Rourke RA, Zabalgoitia M. Calculation of lung flow differential after single-lung transplantationa transesophageal echocardiographic study. Am J Cardiol 2001;87:1170-1173.[Medline]
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Abstract
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