Source of elastin-degrading enzymes in mycotic aortic aneurysms: bacteria or host inflammatory response?

Elastolytic matrix metalloproteinases play a central role in the development of chronic atherosclerotic aortic aneurysms, but mycotic aortic aneurysms are a distinct and unusual form of aneurysm disease caused by bacterial infection. Mycotic aortic aneurysms follow a more rapid and unpredictable course than chronic aneurysm disease and they exhibit a predilection for the suprarenal aorta, further implying unique pathophysiologic mechanisms. The purpose of this study was to examine the nature and source of elastin-degrading enzymes in mycotic aortic aneurysm. Bacterial isolates and aortic tissues were obtained from four consecutive patients undergoing surgical repair of suprarenal mycotic aortic aneurysm. Using an in vitro 3H-labeled elastin degradation assay, elastin-degrading enzyme activity was only observed in the bacteria-conditioned medium from an isolate of Pseudomonas aeruginosa. Elastin-degrading enzyme activity in the aortic tissue homogenate of this patient was abolished by the serine protease inhibitor, phenylmethylsulfonyl fluoride, but it was not suppressed by the metalloproteinase inhibitor, ethylenediamine tetraacetic acid (EDTA). In contrast, elastin-degrading enzyme activity in the bacterial-conditioned medium was decreased by about half by both phenylmethylsulfonyl fluoride and EDTA. Elastin substrate zymography revealed two phenylmethylsulfonyl fluoride-inhibitable elastin-degrading enzyme activities in the aortic tissue homogenate that corresponded to human neutrophil elastase (approximately 30 kDa) and its stable complex with alpha 1-proteinase inhibitor (approximately 80 kDa), but no activity attributable to Pseudomonas elastase, a 33-kDa metal-dependent enzyme. Human neutrophil elastase was readily detected throughout mycotic aortic aneurysm tissues by immunohistochemistry, but elastolytic metalloproteinases were only occasionally observed. The results of this study suggest that the elastin-degrading enzyme produced in mycotic aortic aneurysm are largely serine proteases of host neutrophil origin, rather than elastases produced by the infecting microorganisms or the macrophage-derived metalloproteinases typically observed in atherosclerotic aneurysm disease. Further studies will be needed to extend these findings to a larger number of patients with mycotic aortic aneurysm and those caused by additional microorganisms.     

Endovascular repair for multiple Salmonella mycotic aneurysms of the thoracic aorta presenting with Cardiovocal syndrome.

Salmonella mycotic thoracic aortic aneurysm is a rare but life-threatening condition. We report a 59-year-old man with two Salmonella mycotic thoracic aortic aneurysms, presented with fever and chills associated with hoarseness due to left vocal cord palsy (Cardiovocal syndrome). Successful endovascular repair was performed using two Talent thoracic stent-graft devices deployed separately to cover the two mycotic aneurysms. Subsequent computed tomography at 12 months after the operation confirmed exclusion of the two pseudoaneurysms with no endoleak. With potent antibiotics and careful surveillance program, endovascular repair is a possible alternative to conventional open surgery in the management of mycotic thoracic aortic aneurysms, especially in high-risk patients.     

Mycotic aneurysm of the suprarenal aorta secondary toStreptococcus pneumoniae: An unusual pathogen

Mycotic aneurysms of the suprarenal aorta are rare lesions, accounting for less than 1% of aortic reconstructions for aneurysmal disease. The bacteriology of these lesions differs from the infrarenal aneurysms and primarily consists of Gramnegative organisms. We report an unusual case of an 87-year-old man successfully treated for a ruptured mycotic suprarenal aortic aneurysm caused byStreptococcus pneumoniae. We have not seen a previously reported case where this pathogen has been associated with a suprarenal mycotic aneurysm. The unique bacteriology of these aneurysms is reviewed along with theories of etiology and their classification. The current management of these aneurysms is summarized.     

Evolution of bacterial arteritis into a mycotic aortic aneurysm

Arteritis and mycotic aneurysms have been well described for more than 100 years. The authors report a case of bacterial arteritis that presented with pneumatosis of the aortic wall and that evolved over 1 week into an infected abdominal aortic aneurysm. This case documents the rapid progression from arteritis to mycotic aneurysm, highlighting the need for close radiologic follow-up and aggressive medical and surgical management.     

Endovascular stent-graft repair of a tuberculous mycotic aortic aneurysm

Mycobacterium tuberculosis is a rare cause of mycotic aortic aneurysms, which have been classically treated with a combination of antimycobacterial medical therapy and open surgery. Endovascular therapy has been gaining popularity as an alternative to open surgery for mycotic aneurysms. We report a case of a tuberculous mycotic aneurysm of the descending thoracic aorta that was successfully treated with endovascular stent-graft placement with complete resolution of the pseudoaneurysm at 1 year. We also review other cases in the previously published data to identify factors that may affect the outcome of endovascular treatment of tuberculous mycotic aneurysms.     

Pulmonary homograft repair of a mycotic aortic aneurysm in an infant.

Thoracic aortic aneurysms are rare in children and even more unusual in infants. The vast majority are mycotic. Frequently, those with mycotic thoracic aortic aneurysm do not survive and the diagnosis is made at autopsy. We present the case of an asymptomatic infant found to have a mycotic thoracic aortic aneurysm. The clinical course, diagnosis, and surgical repair of the aneurysm with pulmonary homograft are discussed.     

Outcome after endovascular stent graft treatment for mycotic aortic aneurysm: a systematic review

BACKGROUND: Surgical treatment for mycotic aortic aneurysms is not optimal. Even with a large excision, extensive debridement, in situ or extra-anatomical reconstruction, and with or without lifelong antibiotic treatment, mycotic aneurysms still carry very high mortality and morbidity. The use of endovascular aneurysm repair (EVAR) for mycotic aortic aneurysms simplifies the procedure and provides a good alternative for this critical condition. However, the question remains: if EVAR is placed in an infected bed, what is the outcome of the infection? Does it heal, become aggravated, or even cause a disastrous aortic rupture? In this study, we tried to clarify the risk factors for such an adverse response. METHODS: A literature review was undertaken by using MEDLINE. All relevant reports on endoluminal management of mycotic aortic aneurysms were included. Logistic regressions were applied to identify predictors of persistent infection. RESULTS: A total of 48 cases from 22 reports were included. The life-table analysis showed that the 30-day survival rate was 89.6% +/- 4.4%, and the 2-year survival rate was 82.2% +/- 5.8%. By univariate analysis, age 65 years or older, rupture of the aneurysm (including those with aortoenteric fistula and aortobronchial fistula), and fever at the time of operation were identified as significant predictors of persistent infection, and preoperative use of antibiotics for longer than 1 week and an adjunct procedure combined with EVAR were identified as significant protective factors for persistent infection. However, by multivariate logistic regression analysis, the only significant independent predictors identified were rupture of aneurysm and fever. CONCLUSIONS: EVAR seems a possible alternative method for treating mycotic aortic aneurysms. Identification of the risk factors for persistent infection may help to decrease surgical morbidity and mortality. EVAR could be used as a temporary measure; however, a definite surgical treatment should be considered for patients present with aneurysm rupture or fever.     

Double clostridial mycotic aneurysms of the aorta

Mycotic aortic aneurysm continues to present challenging and difficult management issues with a significant morbidity and mortality. The offending organism in the etiology of this aneurysm can be variable and unusual. The first report of two mycotic aortic aneurysms caused by Clostridium septicum in the same patient is described here. Presentation and management as well as conditions commonly associated with Clostridium septicum infection and a review of all clostridial mycotic aortic aneurysms in the English literature are discussed.     

Diagnosis of mycotic abdominal aortic aneurysm using 67-gallium citrate

Mycotic aneurysms of the abdominal aorta are uncommon, but potentially lethal problems. Clinical subtleties may suggest their presence, but in the past, definitive diagnosis has been dependent on surgical exploration or autopsy findings. A case is presented in which 67-gallium citrate abdominal scanning localized the site of sepsis in an abdominal aortic aneurysm and allowed for prompt and successful surgical therapy. This noninvasive technique is recommended as a adjunct in the diagnosis of mycotic abdominal aortic aneurysms.     

Extra-anatomic revascularization and aortic exclusion for mycotic aneurysms of the infrarenal aorta and iliac arteries in an Asian population

OBJECTIVES: To study the clinical presentation, management and eventual outcome of patients with mycotic abdominal aortic aneurysms managed with aortic exclusion and extra-anatomic reconstruction. DESIGN: A retrospective chart review of 18 cases treated at a single institution. METHODS: Medical records of 18 patients admitted to our institution from October 1997 to July 2006 with a diagnosis of mycotic abdominal aortic aneurysms were reviewed. In all cases, the diagnosis was confirmed by abdominal computed tomography and empirical parenteral antibiotics were administered. Seventeen patients had surgical debridement, aneurysm exclusion, and extra-anatomic reconstruction. The antibiotics were continued in the postoperative period for 6 weeks. RESULTS: Immunosuppression was present in 72%, with diabetes mellitus present in 56%. Salmonella sp was the causative organism in 72% of cases. Most patients presented late, with a 67% incidence of contained rupture. Seventy-two percent needed early or emergency surgery with less than 1 week of preoperative antibiotics. Disease-specific mortality was 39% (7/18). There was 1 late death during the mean follow-up period of 34 +/- 26 months. One patient with an infrarenal aneurysm arising relatively close (neck, 2 cm) to the renal arteries died on table when proximal ligatures cut through the friable aortic wall, resulting in uncontrollable exsanguination. One third of patients on long-term graft surveillance developed mild to moderate stenosis at the anastomotic site. CONCLUSIONS: Empirical antibiotics must be started early, aiming to achieve 1 week of antibiotics prior to surgery. In the Asian population, 3 characteristics are apparent: (1) most patients are immunocompromised; (2) patients present late in the course of disease; and (3) Salmonella is usually responsible. Extra-anatomic bypass may provide a safe option for revascularization of mycotic aneurysms of the iliac arteries and infrarenal aorta.     

Mycotic aneurysms of the carotid arteries--case report and review of the literature

Mycotic aneurysms of the extracranial carotid arteries are rare. We report a new case with a mycotic aneurysm of the carotid bifurcation associated with acute bacterial endocarditis of the aortic valve. A concomitant treatment of both lesions was performed. Twenty-six cases of mycotic aneurysms of the extracranial carotid arteries have been reported in the literature. We present a review of all these cases.     

The Management of Mycotic Aortic Aneurysms: Is there a Role for Endoluminal Treatment?

Background : Mycotic aneurysms are rare. Conventional surgical options include ligation or excision with in-situ or extra-anatomical reconstruction. The use of endoluminal stenting for mycotic aneurysms in the presence of sepsis is controversial, but may be a temporising measure, or sometimes the only option in the management of critically ill patients who are not fit for surgery.

Methods : A literature review was undertaken using Medline, all relevant papers on endoluminal management of mycotic aneurysm were taken into account.

Results : Open surgical repair of mycotic aortic aneurysm is associated with considerable peri-and post-operative morbidity and mortality. Endoluminal treatment with stent-grafts has been introduced as an alternative, and early results are promising.

Conclusion : No level I evidence for the endoluminal treatment of mycotic aneurysms exists. Ideally a randomised controlled trial of open surgery versus endoluminal treatment should be performed but this may be difficult to perform because of the low incidence of infected aneurysms.     

Salmonella spondylodiscitis in patients without sickle cell disease

The optimal treatment of salmonella spondylodiscitis is controversial. The cases of eight patients who had salmonella spondylitis without sickle cell disease were reviewed. Back pain (100%), fever (75%), and elevated C-reactive protein levels (100%) were common, but gastrointestinal symptoms were not (0%). Six patients had positive blood cultures, and the other two had positive tissue cultures. Group C1 salmonella was the most common serotype. Two patients with coexisting aortic mycotic aneurysms had immediate aneurysm resection. Three others responded favorably to appropriate antibiotics, and three required subsequent surgical reconstruction because of neurologic impairment or osseous instability. Clinical outcomes were significantly better than those of 46 previously reported patients. Salmonella spondylodiscitis usually responds favorably to appropriate antibiotics; consequently, a tissue diagnosis is important. Operative interventions are necessary only for patients with coexisting aneurysms or ongoing osseous instability. A ruptured aortic aneurysm with pseudoaneurysm may mimic a paravertebral abscess, and surgery at the site of an unsuspected aneurysm may precipitate life-threatening hemorrhage. Satisfactory results may be depend on early surgical intervention for a mycotic aneurysm and also are related to host immunity.     

Patch closure of aortic annulus mycotic aneurysms

Twenty-three patients with bacterial endocarditis and mycotic aneurysms of the aortic annulus were treated between 1978 and 1985. There were 18 men and 5 women ranging from 24 to 72 years old. All patients had congestive heart failure and positive blood cultures as a complication of the endocarditis and were in New York Heart Association (NYHA) Functional Class III or IV. The aneurysm complicated late prosthetic valve endocarditis in 7 patients and native valve endocarditis in 16. The most common infecting organisms were streptococci (12 patients) and staphylococci (7 patients). The noncoronary sinus was the most frequent site for aneurysm formation. Following debridement of the abscess cavity, the orifice of the aneurysm was closed with a patch of Dacron in 20 patients and autologous pericardium in 3. A prosthetic valve (18 bioprosthetic and 5 mechanical) was secured to the noninfected portion of the native annulus and to the patch at the level of annulus. There were 3 deaths, 1 perioperative and 2 late, each without evidence of residual infection or aortic insufficiency. There are 20 late survivors (87%). After a mean follow-up of 1 year, all patients are in NYHA Functional Class I. Patch closure of mycotic aneurysms involving the aortic annulus permits aggressive debridement of the abscess cavity and affords closure of the orifice without tension. The prosthetic valve can be seated at the level of the native annulus, thus avoiding complicated reconstructive procedures of the aortic root and coronary arteries. This technique is an effective alternative in selected cases of mycotic aneurysms involving the aortic annulus.     

Multiple Mycotic Aortic Aneurysms due to <Emphasis Type="Italic">Streptococcus pneumoniae</Emphasis>

Primary pneumococcal aortic mycotic aneurysms are rare clinical entities. Only a few cases have been reported in the literature. Extremely rare presentation is the occurrence of three simultaneous aneurysms. Treatment usually necessitates intravenous antibiotherapy combined with staged surgical interventions. This report highlights the case of a 52-year-old man with multiple Streptococcus pneumoniae mycotic aneurysms that were simultaneously and successfully treated during a one-stage surgical procedure. The aorta may be prone to infection, especially when its intima is structurally altered by pathologic processes like atherosclerosis, inflammation or trauma. Mycotic aneurysm is a rare but serious vascular condition needing urgent medical and surgical attention because of potential lethal complications.     

Mycotic embolism and embolomycotic aneurysms. Neglected lessons of the past.

During the past decade, nine patients with bacterial endocarditis have required management of mycotic emboli and/or aneurysms in this center. In these patients, 25 separate mycotic emboli or aneurysms were identified. Among these were four visceral, 11 lower extremity, one aortic, one hypogastric, and eight cerebral lesions. Multiple sites were involved in seven of the nine patients (78%). Presenting symptoms were secondary to acute expansion of mycotic aneurysms in three patients and secondary to rupture of aneurysms in four patients. Mycotic emboli produced cerebral infarction in two patients and acute ischemia in six patients. Asymptomatic mycotic aneurysms of the middle cerebral, hepatic, hypogastric, and profunda femoris arteries and asymptomatic emboli to the profunda femoris and tibial arteries were found during angiographic study. Management included resection alone (7 aneurysms), resection and graft replacement (2 aneurysms and 2 emboli), embolectomy (2), or observation. There was no mortality or loss of limb in these patients. This experience underscores the frequent multiplicity of mycotic emboli and/or aneurysms and stresses the importance of empiric angiographic survey to exclude silent yet potentially lethal visceral and cerebral mycotic foci in patients with bacterial endocarditis and peripheral emboli or aneurysms.     

Mycotic aneurysms of the suprarenal abdominal aorta: prolonged survival after in situ aortic and visceral reconstruction

Necrotizing infection of the arterial wall causes rupture and false ("mycotic") aneurysm formation, with a very poor prognosis if untreated. Cure can be achieved by surgical drainage and debridement, with restoration of arterial continuity through uncontaminated tissues. The dilemma of applying these principles to the treatment of mycotic aneurysms of the suprarenal aorta is that no remote or extraanatomic routes are available to maintain perfusion to the viscera. We report the first case of Klebsiella suprarenal mycotic aortic aneurysm successfully treated with in situ prosthetic reconstruction of the aorta and visceral arteries, and we have reviewed the 21 other suprarenal mycotic aortic aneurysms reported in the English-language literature. Repair was performed in 20 of the 22 cases, with in situ prosthetic reconstruction performed in 18. Prolonged survival has been achieved in 16 patients after in situ repair. No long-term survival has been reported after extraanatomic reconstruction of the aorta and visceral arteries in patients with such aneurysms. We conclude that in situ prosthetic reconstruction, accompanied by thorough drainage and debridement, prolonged parenteral antibiotic therapy, and permanent suppressive oral antibiotics, offers the best chance for survival in these patients.     

Cryptic mycotic abdominal aortic aneurysms: diagnosis and management

The incidence of cryptic mycotic abdominal aortic aneurysms has relatively increased since antibiotic therapy has become available. The causative organism is the salmonella group in about 50 per cent of cases. This diagnosis should be strongly entertained in patients with fever of unknown origin, vague abdominal pain, and progressive appearance of a pulsatile abdominal mass. Aortography may be helpful in establishing the diagnosis. Some postoperative graft infections may be due to unrecognized cryptic mycotic infection of the aorta and not from external contamination, as previously supposed. Construction of an axillofemoral bypass graft through clean tissue is advised for the successful treatment of the grossly infected infrarenal aortic aneurysm. Three surviving patients with cryptic mycotic abdominal aortic aneurysms are added to the sixteen surviving patients already reported in the literature.     

Treatment of mycotic aortic aneurysms with endoluminal grafts.

PURPOSE: To report the benefit of endoluminal repair of mycotic aortic aneurysms and highlight the need for a registry. METHODS: Nine patients (five female) were identified over 5 years (1998-2003) as having presumed mycotic aortic aneurysms (12 in total) suitable for endoluminal grafting. A total of nine thoracic and three abdominal were grafted and followed up for a median of 36 months. RESULTS: Six of the aneurysms have resolved and one was converted to an open repair. There was one early death from rupture of a second undiagnosed aneurysm and two late deaths from rupture due to persistent inflammation. Long-term antibiotics have not been mandatory to ensure survival. CONCLUSIONS: Mycotic aortic aneurysms of the thoracic and abdominal aorta do benefit from endoluminal repair, particularly when arising in previously normal aortic tissue. Endoluminal grafting also has a role in the palliation of secondarily infected aortas and so to prove its efficacy in the treatment of all these rare cases a registry is required.     

Multiple mycotic arch-thoraco-abdominal aortic aneurysms: a successful case of in situ graft replacement.

Mycotic aortic aneurysms are an uncommon yet still life-threatening pathology. We report on a 67-year-old male who had a persistent fever and back pain. Contrast enhanced computed tomography (CT) showed multiple aortic aneurysms located in the aortic arch, the descending thoracic aorta and the supraceliac abdominal aorta. After 2 months of antibiotic therapy, a staged operation was carried out with 2-week interval, which includes a graft replacement of aortic arch with elephant trunk technique and a graft replacement of thoraco-abdominal aorta with omental transfer. The postoperative course was uneventful. This case seems to be quite rare in terms of multiplicity and location of mycotic aneurysms. Surgical strategy for this pathology is discussed.