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Surgical Management of Necrotizing Mediastinitis With Large Aortic Pseudoaneurysm
Surgical Management of Necrotizing Mediastinitis With Large Aortic Pseudoaneurysm Andrew T. Chevalier, BA, Minhaj S. Khaja, MD, MBA, and Bo Yang, MD, PhD University of Michigan Medical School, and the Departments of Radiology, and Cardiac Surgery, University of Michigan Frankel Cardiovascular Center, University of Michigan Health System, Ann Arbor, Michigan
We report a patient with necrotizing mediastinitis complicated by a giant retrosternal mycotic pseudoaneurysm and prosthetic valve endocarditis successfully managed with a redo sternotomy under hypothermic circulatory arrest. The approach then included extensive debridement of the mediastinum, replacement of the ascending aorta and aortic arch with selective antegrade cerebral perfusion, redo aortic valve replacement, and wound closure with omental flap and myocutaneous flap. After a 2-year survival, the patient suffered reinfection from hemodialysis. Our approach is also applicable to more common presentations of mediastinitis. (Ann Thorac Surg 2016;101:e143–5) Ó 2016 by The Society of Thoracic Surgeons
N
ecrotizing mediastinitis after open heart operations is very rare but carries a high mortality and is even more dangerous when complicated by an aortic pseudoaneurysm and prosthetic valve endocarditis. We report the operative treatment of a patient with a giant pseudoaneurysm with prosthetic valve endocarditis secondary to necrotizing mediastinitis from a prior surgical wound infection after aortic valve replacement and coronary artery bypass grafting. The extensive damage to mediastinal structures caused by the necrotizing infection greatly complicated management of the patient. Successful management of a pseudoaneurysm caused by necrotizing mediastinitis has not been previously reported. The patient was a 45-year-old man on hemodialysis for end-stage renal disease who underwent an aortic valve replacement and 3-vessel coronary artery bypass grafting at another hospital. The patient presented 3 months later with a Serratia sternal wound infection and abscess with purulent drainage (Fig 1A). A computed tomography scan revealed a 10-cm pseudoaneurysm of the ascending aorta (Figs 1B, 1C), and echocardiography demonstrated prosthetic valve endocarditis with a moderate-to-severe perivalvular leak. Before sternal reentry, cardiopulmonary bypass was initiated with a chimney graft sewn to the right axillary
Accepted for publication Oct 9, 2015. Address correspondence to Dr Yang, Department of Cardiac Surgery, Frankel Cardiovascular Center, The University of Michigan, 1500 E Medical Center Dr, Ann Arbor, MI 48109; email: [email protected].
Ó 2016 by The Society of Thoracic Surgeons Published by Elsevier
artery and a long 27F Avalon cannula (Maquet Cardiovascular, Wayne, NJ) into the right atrium from the right femoral vein. A left ventricular vent was placed into the apex of the left ventricle through a small left anterior thoracotomy. The patient was cooled to 18 C, and the redo sternotomy was performed under hypothermic circulatory arrest (HCA). Upon opening of the chest, purulent drainage surged from the mediastinum beneath the sternum. There were also severe sites of sternal osteomyelitis and extensive necrosis of the mediastinum with foul-smelling fluid. The pseudoaneurysm was exposed, and approximately 200 mL of infected thrombus was removed. After d ebridement of the necrotic tissue in the mediastinum to expose the aorta, a 4-cm hole from the dehiscence of the previous aortotomy was found. The ascending aorta and proximal aortic arch were also necrotic. The innominate artery was quickly dissected out, air was flushed out, and the innominate artery was clamped proximally to achieve selective antegrade cerebral perfusion through the right axillary artery at 10 mL/kg/ min. The ascending aorta was d ebrided to the proximal arch and replaced with a 28-mm homograft under HCA. The homograft was clamped after air was removed, and circulation was resumed. The previous 2 saphenous vein grafts were thrombosed and were ligated proximally. The left internal mammary artery graft was left untouched. The infected prosthetic valve was replaced with a 23-mm Trifecta (St. Jude Medical, SST Paul, MN) aortic valve. Shortly after protamine administration, the patient became asystolic. Cardiac massage was performed, the patient was reheparinized, and cardiopulmonary bypass was reinitiated. After resuscitation, the patient was stabilized and successfully weaned off cardiopulmonary bypass. Before temporary closure of the chest, the mediastinum was extensively d ebrided to remove all necrotic tissue, and the sternum was resected. The patient’s sternal wound was closed 2 days later with an omental flap, bilateral pectoralis major myocutaneous flaps, and bilateral rectus abdominus myocutaneous flaps (Fig 2A). Despite 65 minutes of HCA with 45 minutes of selective antegrade cerebral perfusion and 15 minutes of cardiac massage, the patient was neurologically intact and made a complete recovery. Diverticulitis, a colovesical fistula, and urosepsis developed 7 months after the operation; however, repeated computed tomography CT scan and echocardiogram showed an intact repair, without pseudoaneurysm or endocarditis (Fig 2B). Blood cultures at a routine clinic visit 15 months after the operation were positive for methicillinsensitive Staphylococcus aureus, likely from hemodialysis, and treatment included long-term antibiotics. At 18 months after the operation, the patient presented with ischemic cardiomyopathy with an ejection fraction of 0.30, severe functional mitral regurgitation, moderate tricuspid regurgitation, and moderate aortic regurgitation but no perivalvular leak. A small pseudoaneurysm at the aortic root underneath the right coronary cusp (Fig 2C)
0003-4975/$36.00 http://dx.doi.org/10.1016/j.athoracsur.2015.10.022
e144
CASE REPORT CHEVALIER ET AL MEDIASTINITIS AND AORTIC PSEUDOANEURYSM
Ann Thorac Surg 2016;101:e143–5
Fig 1. (A) Photograph shows the patient’s mediastinal abscess eroding through the skin. (B) Axial image from computed tomography angiography reveals a large aortic pseudoaneurysm (blue arrow) with wide neck (*) posterior to and compressing the sternum (blue arrowhead). (C) A threedimensional volume-rendered left anterior oblique image of the aorta demonstrates a large aortic pseudoaneurysm (blue arrow) originating from the ascending aorta (red arrow) posterior to and compressing the sternum (blue arrowhead).
was noted. At this stage, elective medical management was pursued due to the overall clinical presentation of the patient and the persistent source of potential infection: hemodialysis. The patient died suddenly at home at 20 months after the operation of an unknown cause.
Comment Mediastinitis is a rare but deadly complication of cardiac operations, occurring after 0.5% to 5.6% of cases, with mortality rates of up to 32% [1]. The risk factors include age, diabetes, obesity, and type of procedure, and these realities may not be modifiable [1]. Mediastinitis occasionally can lead to extensive necrosis of mediastinal structures, as in this patient. Fortunately, necrotizing mediastinitis from a wound infection after a cardiac operation rarely occurs. Descending necrotizing mediastinitis, a necrotizing infection from the head or neck traveling into the mediastinum, is more common [2].
Early diagnosis depends on high clinical suspicion and computed tomography imaging of the chest [2]. Mortality estimates in such cases of necrotizing mediastinitis range even higher, up to 80% [2]. Regardless of etiology, the mainstay of treatment for mediastinitis is extensive d ebridement of infected tissue [2]. Pseudoaneurysms are also rare and deadly, occurring after 0.5% of cardiac surgical cases [3], with operative mortality rates of 6.2% to 18% for repair of uncomplicated pseudoaneurysms [3–6]. Rarely, pseudoaneurysms can result from necrotizing mediastinitis. This combination is very difficult to treat. Several studies have documented treatment of pseudoaneurysms [3–6], but none have detailed successful management of a pseudoaneurysm with necrotizing mediastinitis, as reported here. In this case, HCA allowed safe reentry to the chest, and the left ventricular vent through the apex kept the left ventricle decompressed during cooling before the redo sternotomy.
Fig 2. (A) One-month postoperative photograph of the patient’s healed incision. (B) A three-dimensional volume-rendered (3DVR) left anterior oblique (LAO) image of the aorta shows no pseudoaneurysm 7 months after the replacement of the ascending aorta with homograft (red arrowhead). (C) A 3DVR LAO of the aorta 18 months after the operation reveals a highly calcified appearance of the homograft (red arrowhead), and no pseudoaneurysm at the anastomoses, but new aortic root pseudoaneurysm (red arrow).
Ann Thorac Surg 2016;101:e143–5
HCA with selective antegrade cerebral perfusion provided adequate cerebral protection and provided time to replace the necrotic aortic arch. Aggressive d ebridement of all necrotic tissue in the mediastinum, including the aorta, was essential to control infection. The omental flap and myocutaneous flap were effective in closing the sternal wound and lessening the likelihood of recurrence of the mediastinal infection. However, the risk of reinfection of prosthetic valves is high for patients with end-stage renal disease on hemodialysis, and the long-term results are poor due to the risk of recurrent bacteremia from hemodialysis. In summary, necrotizing mediastinitis complicated with a retrosternal aortic pseudoaneurysm and prosthetic valve endocarditis can be successfully managed surgically. This approach is also applicable to more common presentations of mediastinitis.
CASE REPORT CHEVALIER ET AL MEDIASTINITIS AND AORTIC PSEUDOANEURYSM
e145
References 1. Rehman SM, Elzain O, Mitchell J, et al. Risk factors for mediastinitis following cardiac surgery: the importance of managing obesity. J Hosp Infect 2014;88:96–102. 2. Sander A, B€ orgermann J. Update on necrotizing mediastinitis: causes, approaches to management, and outcomes. Curr Infect Dis Rep 2011;13:278–86. 3. Atik FA, Navia JL, Svensson LG, et al. Surgical treatment of pseudoaneurysm of the thoracic aorta. J Thorac Cardiovasc Surg 2006;132:379–85. 4. Mohammadi S, Bonnet N, Leprince P, et al. Reoperation for false aneurysm of the ascending aorta after its prosthetic replacement: surgical strategy. Ann Thorac Surg 2005;79: 147–52. 5. Villavicencio MA, Orszulak TA, Sundt TM, et al. Thoracic aorta false aneurysm: what surgical strategy should be recommended? Ann Thorac Surg 2006;82:81–9. 6. Dumont E, Carrier M, Cartier R, et al. Repair of aortic false aneurysm using deep hypothermia and circulatory arrest. Ann Thorac Surg 2004;78:117–21.
We report a patient with necrotizing mediastinitis complicated by a giant retrosternal mycotic pseudoaneurysm and prosthetic valve endocarditis successfully managed with a redo sternotomy under hypothermic circulatory arrest. The approach then included extensive debridement of the mediastinum, replacement of the ascending aorta and aortic arch with selective antegrade cerebral perfusion, redo aortic valve replacement, and wound closure with omental flap and myocutaneous flap. After a 2-year survival, the patient suffered reinfection from hemodialysis. Our approach is also applicable to more common presentations of mediastinitis. (Ann Thorac Surg 2016;101:e143–5) Ó 2016 by The Society of Thoracic Surgeons
N
ecrotizing mediastinitis after open heart operations is very rare but carries a high mortality and is even more dangerous when complicated by an aortic pseudoaneurysm and prosthetic valve endocarditis. We report the operative treatment of a patient with a giant pseudoaneurysm with prosthetic valve endocarditis secondary to necrotizing mediastinitis from a prior surgical wound infection after aortic valve replacement and coronary artery bypass grafting. The extensive damage to mediastinal structures caused by the necrotizing infection greatly complicated management of the patient. Successful management of a pseudoaneurysm caused by necrotizing mediastinitis has not been previously reported. The patient was a 45-year-old man on hemodialysis for end-stage renal disease who underwent an aortic valve replacement and 3-vessel coronary artery bypass grafting at another hospital. The patient presented 3 months later with a Serratia sternal wound infection and abscess with purulent drainage (Fig 1A). A computed tomography scan revealed a 10-cm pseudoaneurysm of the ascending aorta (Figs 1B, 1C), and echocardiography demonstrated prosthetic valve endocarditis with a moderate-to-severe perivalvular leak. Before sternal reentry, cardiopulmonary bypass was initiated with a chimney graft sewn to the right axillary
Accepted for publication Oct 9, 2015. Address correspondence to Dr Yang, Department of Cardiac Surgery, Frankel Cardiovascular Center, The University of Michigan, 1500 E Medical Center Dr, Ann Arbor, MI 48109; email: [email protected].
Ó 2016 by The Society of Thoracic Surgeons Published by Elsevier
artery and a long 27F Avalon cannula (Maquet Cardiovascular, Wayne, NJ) into the right atrium from the right femoral vein. A left ventricular vent was placed into the apex of the left ventricle through a small left anterior thoracotomy. The patient was cooled to 18 C, and the redo sternotomy was performed under hypothermic circulatory arrest (HCA). Upon opening of the chest, purulent drainage surged from the mediastinum beneath the sternum. There were also severe sites of sternal osteomyelitis and extensive necrosis of the mediastinum with foul-smelling fluid. The pseudoaneurysm was exposed, and approximately 200 mL of infected thrombus was removed. After d ebridement of the necrotic tissue in the mediastinum to expose the aorta, a 4-cm hole from the dehiscence of the previous aortotomy was found. The ascending aorta and proximal aortic arch were also necrotic. The innominate artery was quickly dissected out, air was flushed out, and the innominate artery was clamped proximally to achieve selective antegrade cerebral perfusion through the right axillary artery at 10 mL/kg/ min. The ascending aorta was d ebrided to the proximal arch and replaced with a 28-mm homograft under HCA. The homograft was clamped after air was removed, and circulation was resumed. The previous 2 saphenous vein grafts were thrombosed and were ligated proximally. The left internal mammary artery graft was left untouched. The infected prosthetic valve was replaced with a 23-mm Trifecta (St. Jude Medical, SST Paul, MN) aortic valve. Shortly after protamine administration, the patient became asystolic. Cardiac massage was performed, the patient was reheparinized, and cardiopulmonary bypass was reinitiated. After resuscitation, the patient was stabilized and successfully weaned off cardiopulmonary bypass. Before temporary closure of the chest, the mediastinum was extensively d ebrided to remove all necrotic tissue, and the sternum was resected. The patient’s sternal wound was closed 2 days later with an omental flap, bilateral pectoralis major myocutaneous flaps, and bilateral rectus abdominus myocutaneous flaps (Fig 2A). Despite 65 minutes of HCA with 45 minutes of selective antegrade cerebral perfusion and 15 minutes of cardiac massage, the patient was neurologically intact and made a complete recovery. Diverticulitis, a colovesical fistula, and urosepsis developed 7 months after the operation; however, repeated computed tomography CT scan and echocardiogram showed an intact repair, without pseudoaneurysm or endocarditis (Fig 2B). Blood cultures at a routine clinic visit 15 months after the operation were positive for methicillinsensitive Staphylococcus aureus, likely from hemodialysis, and treatment included long-term antibiotics. At 18 months after the operation, the patient presented with ischemic cardiomyopathy with an ejection fraction of 0.30, severe functional mitral regurgitation, moderate tricuspid regurgitation, and moderate aortic regurgitation but no perivalvular leak. A small pseudoaneurysm at the aortic root underneath the right coronary cusp (Fig 2C)
0003-4975/$36.00 http://dx.doi.org/10.1016/j.athoracsur.2015.10.022
e144
CASE REPORT CHEVALIER ET AL MEDIASTINITIS AND AORTIC PSEUDOANEURYSM
Ann Thorac Surg 2016;101:e143–5
Fig 1. (A) Photograph shows the patient’s mediastinal abscess eroding through the skin. (B) Axial image from computed tomography angiography reveals a large aortic pseudoaneurysm (blue arrow) with wide neck (*) posterior to and compressing the sternum (blue arrowhead). (C) A threedimensional volume-rendered left anterior oblique image of the aorta demonstrates a large aortic pseudoaneurysm (blue arrow) originating from the ascending aorta (red arrow) posterior to and compressing the sternum (blue arrowhead).
was noted. At this stage, elective medical management was pursued due to the overall clinical presentation of the patient and the persistent source of potential infection: hemodialysis. The patient died suddenly at home at 20 months after the operation of an unknown cause.
Comment Mediastinitis is a rare but deadly complication of cardiac operations, occurring after 0.5% to 5.6% of cases, with mortality rates of up to 32% [1]. The risk factors include age, diabetes, obesity, and type of procedure, and these realities may not be modifiable [1]. Mediastinitis occasionally can lead to extensive necrosis of mediastinal structures, as in this patient. Fortunately, necrotizing mediastinitis from a wound infection after a cardiac operation rarely occurs. Descending necrotizing mediastinitis, a necrotizing infection from the head or neck traveling into the mediastinum, is more common [2].
Early diagnosis depends on high clinical suspicion and computed tomography imaging of the chest [2]. Mortality estimates in such cases of necrotizing mediastinitis range even higher, up to 80% [2]. Regardless of etiology, the mainstay of treatment for mediastinitis is extensive d ebridement of infected tissue [2]. Pseudoaneurysms are also rare and deadly, occurring after 0.5% of cardiac surgical cases [3], with operative mortality rates of 6.2% to 18% for repair of uncomplicated pseudoaneurysms [3–6]. Rarely, pseudoaneurysms can result from necrotizing mediastinitis. This combination is very difficult to treat. Several studies have documented treatment of pseudoaneurysms [3–6], but none have detailed successful management of a pseudoaneurysm with necrotizing mediastinitis, as reported here. In this case, HCA allowed safe reentry to the chest, and the left ventricular vent through the apex kept the left ventricle decompressed during cooling before the redo sternotomy.
Fig 2. (A) One-month postoperative photograph of the patient’s healed incision. (B) A three-dimensional volume-rendered (3DVR) left anterior oblique (LAO) image of the aorta shows no pseudoaneurysm 7 months after the replacement of the ascending aorta with homograft (red arrowhead). (C) A 3DVR LAO of the aorta 18 months after the operation reveals a highly calcified appearance of the homograft (red arrowhead), and no pseudoaneurysm at the anastomoses, but new aortic root pseudoaneurysm (red arrow).
Ann Thorac Surg 2016;101:e143–5
HCA with selective antegrade cerebral perfusion provided adequate cerebral protection and provided time to replace the necrotic aortic arch. Aggressive d ebridement of all necrotic tissue in the mediastinum, including the aorta, was essential to control infection. The omental flap and myocutaneous flap were effective in closing the sternal wound and lessening the likelihood of recurrence of the mediastinal infection. However, the risk of reinfection of prosthetic valves is high for patients with end-stage renal disease on hemodialysis, and the long-term results are poor due to the risk of recurrent bacteremia from hemodialysis. In summary, necrotizing mediastinitis complicated with a retrosternal aortic pseudoaneurysm and prosthetic valve endocarditis can be successfully managed surgically. This approach is also applicable to more common presentations of mediastinitis.
CASE REPORT CHEVALIER ET AL MEDIASTINITIS AND AORTIC PSEUDOANEURYSM
e145
References 1. Rehman SM, Elzain O, Mitchell J, et al. Risk factors for mediastinitis following cardiac surgery: the importance of managing obesity. J Hosp Infect 2014;88:96–102. 2. Sander A, B€ orgermann J. Update on necrotizing mediastinitis: causes, approaches to management, and outcomes. Curr Infect Dis Rep 2011;13:278–86. 3. Atik FA, Navia JL, Svensson LG, et al. Surgical treatment of pseudoaneurysm of the thoracic aorta. J Thorac Cardiovasc Surg 2006;132:379–85. 4. Mohammadi S, Bonnet N, Leprince P, et al. Reoperation for false aneurysm of the ascending aorta after its prosthetic replacement: surgical strategy. Ann Thorac Surg 2005;79: 147–52. 5. Villavicencio MA, Orszulak TA, Sundt TM, et al. Thoracic aorta false aneurysm: what surgical strategy should be recommended? Ann Thorac Surg 2006;82:81–9. 6. Dumont E, Carrier M, Cartier R, et al. Repair of aortic false aneurysm using deep hypothermia and circulatory arrest. Ann Thorac Surg 2004;78:117–21.