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Vascular prosthesis rupture caused by contact with rib stump after thoracic aorta replacement

2009; Elsevier BV; Volume: 50; Issue: 1 Linguagem: Inglês

10.1016/j.jvs.2009.01.064

1097-6809

Hiroshi Yamamoto, Fumio Yamamoto, Kazuyuki Ishibashi, Yasuharu Noishiki,

Infectious Aortic and Vascular Conditions

A 42-year-old male with Marfan syndrome, who had undergone aortic root and total arch replacement for type-A acute aortic dissection at the age of 40, underwent descending aorta replacement with woven Dacron (Vascutek Ltd., Renfrewshire, Scotland) because of pseudoaneurysm at the site of the distal anastomosis and an enlarged pseudolumen of the dissecting descending aorta. The fourth and eighth ribs were cut at their anterior and posterior sites to allow wide exposure of the entire descending aorta. Postoperative computed tomographic scanning showed that the vascular prosthesis posteriorly contacted the eighth rib stump. On the postoperative day 25, the patient collapsed and developed severe hypotension. Emergency thoracotomy revealed a 6 mm in diameter hole on the posterior side of the vascular prosthesis. One day later, the patient died of cardiac dysfunction resulting from sustained hypotension. Electron microscopic examination of the vascular prosthesis showed that the hole was caused by frayed fabric and disrupted polyester fibers. Our experience warns that a woven polyester vascular prosthesis could rupture within 3 weeks of contacting a rib stump. A 42-year-old male with Marfan syndrome, who had undergone aortic root and total arch replacement for type-A acute aortic dissection at the age of 40, underwent descending aorta replacement with woven Dacron (Vascutek Ltd., Renfrewshire, Scotland) because of pseudoaneurysm at the site of the distal anastomosis and an enlarged pseudolumen of the dissecting descending aorta. The fourth and eighth ribs were cut at their anterior and posterior sites to allow wide exposure of the entire descending aorta. Postoperative computed tomographic scanning showed that the vascular prosthesis posteriorly contacted the eighth rib stump. On the postoperative day 25, the patient collapsed and developed severe hypotension. Emergency thoracotomy revealed a 6 mm in diameter hole on the posterior side of the vascular prosthesis. One day later, the patient died of cardiac dysfunction resulting from sustained hypotension. Electron microscopic examination of the vascular prosthesis showed that the hole was caused by frayed fabric and disrupted polyester fibers. Our experience warns that a woven polyester vascular prosthesis could rupture within 3 weeks of contacting a rib stump. Vascular prosthesis dilation and resultant rupture have been reported in knitted or woven Dacron prostheses.1Wilson S.E. Krug R. Mueller G. Wilson L. Late disruption of Dacron aortic grafts.Ann Vasc Surg. 1997; 11: 383-386Abstract Full Text PDF PubMed Scopus (37) Google Scholar, 2Kawata M. Morota T. Takamoto S. Kubota H. Kitahori K. Non-anastomotic rupture in the guideline of a Dacron thoracic aortic graft.J Vasc Surg. 2005; 42: 573Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar, 3Shingu Y. Aoki H. Ebuoka N. Eya K. Takigami K. Oba J. Late rupture of knitted Dacron graft.Ann Thorac Cardiovasc Surg. 2005; 11: 343-345PubMed Google Scholar, 4Kawamura M. Ogino H. Matsuda H. Minatoya K. Sasaki H. Kitamura S. Late-stage, nonanastomotic rupture of double-velour Dacron graft after descending aortic replacement.J Thorac Cardiovasc Surg. 2006; 132: 961-962Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar However, a traumatic rupture of Dacron prosthesis is rare. We describe a patient with Marfan syndrome who underwent thoracic aortic replacement and in whom a vascular prosthesis ruptured by contact with a rib that had been cut to allow a clear view of the thoracic aorta. A 40-year-old male with Marfan syndrome underwent aortic root and total arch replacement with an elephant trunk due to type-A acute aortic dissection. Follow-up computed tomography (CT) scans at the age of 42 revealed a pseudo-aneurysm at the site of the distal anastomosis of the replaced arch and pseudolumen enlargement of the dissecting descending aorta (Fig 1). A left posterolateral thoracotomy was performed with a divided endotracheal tube under general anesthesia. The fourth and eighth ribs were cut at their anterior and posterior sites to expose the entire descending aorta. The sharp edges of the rib stumps were smoothed with a rasp. Visceral organ and lower limb perfusion with cardiopulmonary bypass was initiated after systemic heparinization (3 mg/kg body weight). The branched arch graft implanted in the previous surgery was clamped immediately distal to its branch graft toward the left subclavian artery, and the native aorta was then clamped distal to its aneurysmal site. The patient subsequently underwent descending aorta replacement using 24-mm woven Dacron prosthesis (Vascutek Ltd., Renfrewshire, Scotland). Reconstruction of the intercostal artery was not required because motor evoked potentials (MEP) did not change throughout the procedure. The graft was placed in the bed of the opened aneurysm, and we tried to cover the graft with the aneurysmal wall as wide as possible, but the aneurysmal wall was not large enough to cover the part of graft surface facing the rib stump. Systemic infection was undetectable during the postoperative course. A CT scan as a routine postoperative check-up was performed on postoperative day (POD) 19, showing that the new vascular prosthesis was in contact with the posterior edge of the stump of the eighth rib (Fig 2). It was not predicted that the vascular prosthesis might rupture because we thought that the edge of the rib stump had been carefully smoothed to specifically avoid damaging the prosthesis. There was no postoperative hemodynamic problem or no abnormal shadow indicating hemothorax in the postoperative chest roentgenogram until POD 24. On POD 25, the patient suddenly collapsed in the ward with hypotension lower than 30 mm Hg of systolic pressure, followed by tracheal intubation under cardiopulmonary resuscitation. The chest roentgenogram showed a massive hemothorax, and he was taken to the intensive care unit (ICU). We suspected a rupture of anastomotic sites as the cause of hypotension and performed an emergent thoracotomy in the ICU. Massive coagulated blood was evacuated through the thoracotomy. A hole of approximately 6 mm in diameter was found on the dorsal (costal) side of the vascular prosthesis (Fig 3), and we closed it using a 4-0 polypropylene suture. Approximately 40 minutes had passed since collapse when the hole was closed in the ICU. Percutaneous cardiopulmonary support was initiated to stabilize the patient's hemodynamics, because the cardiac function evaluated by echocardiography was extremely deteriorated due to a sustained hypotension. In spite of bypass support, the deteriorated cardiac function was not improved, and fully dilated pupils with loss of light reflex were observed. The patient died on the following day after discontinuation of bypass support under his family's informed consent. An autopsy revealed no apparent causes of the rupture at either the proximal or distal anastomotic sites, but the hole was located at the site of the prosthesis corresponding to the level of the posterior stump of the eighth rib. The edge of the rib stump, which we thought had been carefully smoothed with a rasp, remained sharper than predicted (Fig 4). Electron microscopic examination of the prosthesis revealed that the Dacron fabric had frayed (Fig 5, A) and that the weave had become disrupted (Fig 5, B).Fig 2Computed tomographic scan on postoperative day 19 shows contact between graft (G) and rib stump is evident.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 3Emergency thoracotomy findings. A hole (white arrow) of approximately 6 mm in diameter is located on the dorsal (costal) side of vascular prosthesis.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 4Posterior aspect of thorax in autopsy. Posteriorly cut rib shows a stump (white arrow). Rupture hole was located at graft site corresponding to level of rib stump.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 5Electron microscopic examination of vascular prosthesis. Fabric (A) is frayed and fibers of woven polyester graft are disrupted (B).View Large Image Figure ViewerDownload Hi-res image Download (PPT) The quality of vascular prostheses has remarkably improved during the past two decades in terms of durability, porosity, and antithrombotic activity. Most reported disruptions of vascular prostheses have been aneurysmal changes in Dacron grafts located in the descending aortic, infra-renal aortic, or peripheral vascular levels.1Wilson S.E. Krug R. Mueller G. Wilson L. Late disruption of Dacron aortic grafts.Ann Vasc Surg. 1997; 11: 383-386Abstract Full Text PDF PubMed Scopus (37) Google Scholar, 2Kawata M. Morota T. Takamoto S. Kubota H. Kitahori K. Non-anastomotic rupture in the guideline of a Dacron thoracic aortic graft.J Vasc Surg. 2005; 42: 573Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar, 3Shingu Y. Aoki H. Ebuoka N. Eya K. Takigami K. Oba J. Late rupture of knitted Dacron graft.Ann Thorac Cardiovasc Surg. 2005; 11: 343-345PubMed Google Scholar, 4Kawamura M. Ogino H. Matsuda H. Minatoya K. Sasaki H. Kitamura S. Late-stage, nonanastomotic rupture of double-velour Dacron graft after descending aortic replacement.J Thorac Cardiovasc Surg. 2006; 132: 961-962Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar Traumatic rupture of a vascular prosthesis due to contact with external hard tissue is rare. Tanaka et al reported a case that the vascular prosthesis covered with the aneurysmal wall was ruptured by calcified mural plaque of the aneurysmal wall 18 days after graft replacement of a thoracoabdominal aortic aneurysm.5Tanaka H. Okada K. Yamashita T. Kawanishi Y. Matsumori M. Okita Y. Disruption of the vascular prosthesis caused by aortic calcification after replacement of the thoracoabdominal aortic aneurysm.Ann Thorac Surg. 2006; 82: 1097-1099Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar We routinely cut ribs at the anterior and posterior sites to gain a broad view of a long segment of the thoracic aorta. Because the cut edges of rib stumps can be sharp enough to injure the lung, they are routinely smoothed carefully with a rasp. Although the sharp edges of rib stumps were also smoothed in the present case, the vascular prosthesis contacting one of them ruptured within only 3 weeks after implantation, suggesting that mechanical forces arising from such contact can rapidly damage such grafts. Autopsy revealed that the rupture did not result from a linear cut or hole punched out by the sharp edge of a rib stump, but electron microscopic examination of the vascular prosthesis revealed that the woven polyester weave on the margin of the hole was disrupted (Fig 5, A), suggesting that fabric had become frayed and thinned through friction caused by the vascular prosthesis being repeatedly rubbed with the hard and rough surface of the rib stump. Graft elongation and kinking might contribute to contact between a vascular prosthesis and a rib stump. To predict at the time of graft implantation the direction in which an elongated graft will kink is very difficult. Our experience suggests that the configuration of a graft should be assessed by CT scanning within 2 weeks of implantation. Whether rupture can be prevented by placing artificial or biologic materials between a vascular prosthesis and the surface of a rib stump has not been investigated. To avoid graft replacement through a thoracotomy, a possible alternative procedure may include an endovascular technique. Stent graft placement in the descending thoracic aorta in Marfan patients with previous aortic surgery has been feasible to avoid a repeated aortic surgery for an enlargement of the aorta or of the false lumen by stenting the proximal entry tear with a stent graft.6Akin I. Kische S. Rehders T.C. Chatterjee T. Schneider H. Körber T. et al.Current role of endovascular therapy in Marfan patients with previous aortic surgery.Vasc Health Risk Manag. 2008; 4: 59-66Crossref PubMed Scopus (14) Google Scholar Walsh et al compared the results of open surgery with endovascular repair for thoracic aortic disease by using meta-analysis of the 17 eligible studies and concluded that endovascular thoracic aortic repair reduces perioperative mortality and neurologic morbidity in patients with descending thoracic aortic aneurysms.7Walsh S.R. Tang T.Y. Sadat U. Naik J. Gaunt M.E. Boyle J.R. et al.Endovascular stenting versus open surgery for thoracic aortic disease: systematic review and meta-analysis of perioperative results.J Vasc Surg. 2008; 47: 1094-1098Abstract Full Text Full Text PDF PubMed Scopus (173) Google Scholar However, long stent grafts have been reported to be associated with spinal cord ischemia by occluding the intercostal artery or collaterals for the artery of Adamkiewicz.8Kawaharada N. Morishita K. Kurimoto Y. Hyodoh H. Ito T. Harada R. et al.Spinal cord ischemia after elective endovascular stent-graft repair of the thoracic aorta.Eur J Cardiothorac Surg. 2007; 31: 998-1003Crossref PubMed Scopus (60) Google Scholar Greenberg et al experienced two stent graft-related deaths (aortoesophageal fistula; proximal aortic occlusion) of 22 patients who underwent endovascular grafting to complete the proximal procedure after aortic arch repair with an elephant trunk,9Greenberg R.K. Haddad F. Svensson L. O'Neill S. Walker E. Lyden S.P. et al.Hybrid approaches to thoracic aortic aneurysms The role of endovascular elephant trunk completion.Circulation. 2005; 112: 2619-2626Crossref PubMed Scopus (158) Google Scholar implying that endovascular completion of elephant trunks may be feasible but require further technical progress to prevent postoperative life-threatening complications. In conclusion, the anatomic course of any prosthetic graft placed in proximity to potentially sharp skeletal structures should be thoroughly investigated at the time of surgery and measures implemented to mitigate or prevent subsequent graft erosion and rupture. If postoperative CT scanning shows contact between a vascular prosthesis and a rib stump, then repeated surgery should be considered to prevent rupture of the graft.