Analysis of Postsurgical Aortic False Aneurysm in 27 Patients

Abstract

Aortic false aneurysm is a rare complication after cardiac surgery. In recent years, improved results have been reported in regard to the surgical management of these high-risk lesions.

We retrospectively examined 28 consecutive cases (in 27 patients) of postsurgical aortic false aneurysm diagnosed at our institution from May 1999 through December 2011. Twenty-four patients underwent reoperation. Cardiopulmonary bypass was instituted before sternotomy in 15 patients (63%). Isolated repair of the aortic false aneurysm was performed in 15 patients. Four patients (including one who had already undergone repeat false-aneurysm repair) declined surgery in favor of clinical monitoring.

Eleven patients were asymptomatic at the time of diagnosis. In the other 16, the main cause was infection in 7, and previous operation for acute aortic dissection in 9. The in-hospital mortality rate was 16.6% (4 patients, 3 of whom had infective false aneurysms). Relevant postoperative sequelae were noted in 7 patients (29%). The cumulative 1-year and 5-year survival rates were 83% and 62%, respectively. The 4 patients who did not undergo reoperation were alive at a median interval of 23 months (range, 9–37 mo). Two underwent imaging evaluations; in one, computed tomography revealed an 8-mm increase of the false aneurysm's maximal diameter at 34 months.

Aortic false aneurysm can develop silently. Surgical procedures should be proposed even to asymptomatic patients because of the unpredictable evolution of the condition. Radical aortic-graft replacement should be chosen rather than simple repair, because recurrent false aneurysm is possible.

Aortic false aneurysm is a rare sequela of surgery on the thoracic aorta.¹ Infection, pathologic conditions of the aortic wall, dissection of the native aorta, and excessive use of biological glue have been recognized as causative factors.^2,3 The development and expansion of aortic false aneurysms is often silent.³ Their evolution is unpredictable, and rupture can be fatal. Despite advances in endovascular techniques, the treatment is chiefly surgical.⁴ In recent years, improved results in surgical management have been reported^4–6; however, treatment is still burdened by a high morbidity rate.

Herein, we provide the midterm results of our experience in the treatment of this challenging pathologic condition, and we discuss the evolution of aortic false aneurysm in patients who declined surgical repair or were deemed unsuitable for reoperation.

Patients and Methods

We retrospectively examined 28 consecutive cases (in 27 patients) of postsurgical aortic false aneurysm diagnosed at our institution from May 1999 through December 2011. These lesions involved the thoracic aorta from the aortic root to the distal arch. Twenty-four of the patients underwent reoperation. The mean age at the time of reoperation was 64 ± 15 years (range, 21–87 yr) and 17 of the 24 patients (71%) were men. Two patients had Marfan syndrome. The median interval between the previous procedure and reoperation was 3.6 years (range, 1 mo–21.9 yr). The mean follow-up period was 46 ± 40 months (range, 1–147 mo). Four patients, including one previously reoperated on for aortic false aneurysm, declined reoperation or were deemed unsuitable for a repeat procedure and entered clinical monitoring. Their mean age upon the diagnosis of false aneurysm was 67 ± 12 years, and the median interval between their prior operation and the detection of the lesion was 6.5 years (range, 5.5–12.3 yr). Our local ethics committee waived the need for informed consent in this study.

Previous Operations Performed

The indications for cardiac surgery at the previous surgical procedure were aortic aneurysm (12 of 27 patients; 44%), acute aortic dissection (8 patients; 30%), pathologic conditions of the aortic valve (4 patients; 15%), repeat aortic false aneurysm in 1 patient already operated on for that condition, mitral regurgitation (1 patient), and coronary artery disease (1 patient). Twenty-one patients had undergone previous aortic surgery, and the use of BioGlue® (CryoLife Inc.; Kennesaw, Ga) was reported in 12 of those cases. Table I lists the previous operations and concomitant procedures performed.

TABLE I. Previous Operations Performed in 21 of the 27 Patients

Indications for Reoperation and the Surgical Technique

The presence of a postsurgical aortic false aneurysm, regardless of size, was the main indication for reoperation in all patients. False aneurysm was defined as a lesion containing blood, resulting from disruption of the arterial wall with extravasation of blood contained by periarterial connective tissue and not by the arterial wall layers. A median sternotomy approach was invariably used. Cardiopulmonary bypass (CPB) was instituted before sternotomy in 15 of 24 patients (63%): through the femoral vessels in 14 patients, and through the right axillary artery and femoral vein in 1 patient. In the other 9 patients, CPB was started after sternotomy: in 5 through the femoral vessels, in 2 through the right axillary artery and right atrium, and in 2 via aortic–right atrial cannulation. We have already described our algorithm in managing resternotomy in relation to false-aneurysm location.⁷ Initially, this strategy usually involved CPB before reentry; however, as we gained experience, we began to start CPB before resternotomy only in the instance of a minimal space between the aorta or the heart and the posterior aspect of the sternum, as shown on chest imaging. In 2 patients, we chose to perform repeat sternotomy during a short period of deep hypothermic circulatory arrest (DHCA) because the lesion firmly adhered to the chest (Fig. 1). Because of severe aortic regurgitation and a false aneurysm adhering to the sternum in one patient, we performed—adjunctively to CPB before sternotomy—a small left anterior thoracotomy with a placement of an intraventricular vent cannula to achieve satisfactory decompression of the left ventricle. In 4 patients, the false aneurysm ruptured during repeat sternotomy. In 2, CPB had been already established before the reentry. In the other 2, CPB was promptly started through the already-dissected femoral vessels, and blood loss was successfully managed in such a manner as to avoid hemodynamic imbalance and systemic hypoperfusion. Closure of the false aneurysm's entry site by means of direct suturing was performed in 15 of the 24 patients (63%), whereas a more complex and extensive procedure was necessary in the other 9. Table II describes the operative procedures that were performed. The mean CPB time was 152 ± 75 minutes (range, 66–318 min), and the mean duration of aortic cross-clamping was 96 ± 58 minutes (range, 4–220 min). In one patient, aortic cross-clamping and cardioplegic arrest were not necessary, because the false aneurysm's entry site was easily accessible. In 5 patients, DHCA alone was used (mean duration, 16 ± 8 min); moderate hypothermic circulatory arrest and antegrade bihemispheric selective cerebral perfusion were used in one patient (perfusion time, 21 min). In 3 patients, we were unable to reestablish normal coronary perfusion. In one, we placed a venous graft in the right coronary artery because of signs of ischemia during weaning from CPB. In the other 2 patients, it was necessary to interpose a Dacron graft between the vascular prosthesis and the right coronary ostium.

Fig. 1 Computed tomograms in A) sagittal and B) axial projections show a false aneurysm arising from an aortotomy (arrow). These images fully characterize the relationship between the lesion, sternum, and mediastinal structures. In this patient, cardiopulmonary bypass was established before chest reentry. Because of the strict adherence between the lesion and the posterior aspect of the sternum, resternotomy was performed during a short period of deep hypothermic circulatory arrest. Despite this approach, the aortic false aneurysm ruptured during chest reentry.

TABLE II. Operative Procedures Performed in 24 of the 27 Patients

Statistical Analysis

Continuous variables were expressed as mean ± SD. Survival rates and freedom from reoperation were calculated by means of the Kaplan-Meier method. Statistical analyses were performed with use of the Stat-View Statistical Software Package version 5.0 (SAS Institute Inc; Cary, NC) and NCSS 2001 (NCSS; Kaysville, Utah).

Results

Aortic false aneurysm was diagnosed during routine follow-up examination in 11 asymptomatic patients. Table III presents the symptoms reported in the other 16 patients.

TABLE III. Clinical Presentation of the 27 Patients upon the Diagnosis of Aortic False Aneurysm

Sites and Causes of the Aortic False Aneurysms

Details of the false-aneurysm sites are reported in Table IV. Nine patients had undergone previous acute aortic dissection repair, 2 patients had Marfan syndrome, and 1 was diagnosed with Loeys-Dietz syndrome. In 7 patients, we found infection to be the main cause. Along with intraoperative findings, diagnosis was defined by the presence of positive preoperative blood cultures, intraoperative tissue cultures, or both; and by a patient's history of mediastinitis, endocarditis, or sepsis characterized by false-aneurysm development within a reasonable time. In 6 patients, evaluation by computed tomography (CT), positron emission tomography, or echocardiography was performed soon after the infectious symptoms occurred; however, these methods did not reveal the aortic false aneurysm. The mean interval between infection and aortic false-aneurysm detection was 5 ± 2 months. One patient developed aortic false aneurysm with fever and dyspnea 3 months after hospitalization, because of staphylococcal sepsis. Similar symptoms were found in a patient who underwent reoperation for aortic false aneurysm 7 months after ascending aorta replacement that had been complicated by sternal-wound infection (no culture results were then available); at reoperation, blood cultures and tissue samples were negative. Five patients had aortic false aneurysms diagnosed during hospitalization for septic conditions, as follows: 2 patients had Enterococcus faecalis, one had methicillin-resistant Staphylococcus aureus (MRSA), and one had Streptococcus mitis; and the patient with MRSA had composite-valve-graft prosthetic endocarditis. In 2 of the 5 patients, aortic tissue cultures had the same bacterial positivity as their blood cultures.

TABLE IV. Site of the Aortic False Aneurysm in the 27 Patients

In-Hospital Outcomes

The in-hospital mortality rate was 16.6% (4 patients). Three of the 4 patients had infective aortic false aneurysms, and one presented with preoperative septic shock. The postoperative course was complicated in 7 patients (29%). Early reoperation for excessive bleeding was necessary in 2 patients (9%). In 4 patients, neurologic deficits occurred, one permanent and 3 transient. In 3 patients, pulmonary insufficiency necessitated longer respiratory weaning times and longer stays in the intensive care unit.

Survival and Reoperation

Surgical Population. The mean follow-up time for all the patients was 46 ± 40 months (range, 1–147 mo). There were 6 late deaths; the cumulative 1- and 5-year survival rates were 83% and 62%, respectively (Fig. 2). Three patients had recurrent aortic false aneurysm. In all 3, false-aneurysm closure had been performed by means of direct suturing during the previous procedure. Two underwent a second reoperation. Overall freedom from recurrence of aortic false aneurysm was 100% and 80% at 1 year and 5 years, respectively. Clinical Monitoring. The first patient who declined reoperation in favor of clinical monitoring was a 77-year-old man who presented in poor general condition aggravated by neurocognitive deficit. Aortic false aneurysm was diagnosed 70 months after a Bentall operation, and CT showed a left coronary ostium leak with a maximal lesion diameter of 20 mm. He underwent regular CT follow-up scanning, which showed an increase of 8 mm in the maximal diameter of the aneurysm at 34 months. The 2nd patient, a 77-year-old man who underwent annual CT monitoring, had been diagnosed with aortic false aneurysm at the proximal suture line 149 months after supracoronary ascending aorta replacement. He declined reoperation and further CT scanning. He was alive and asymptomatic 9 months after diagnosis. The 3rd patient was a 59-year-old man who had undergone supracoronary ascending aorta and aortic valve replacement for acute aortic dissection and subsequent reoperation for aortic root replacement (Bentall procedure). After 66 months, an aortic false aneurysm at the distal ascending suture line was detected, during CT scanning for respiratory insufficiency caused by chronic obstructive pulmonary disease and right hemidiaphragm elevation. Diffuse, substantial calcification was seen at the proximal arch and descending thoracic aorta. The patient declined reoperation because of the extent and risk of the procedure. He was alive 11 months after diagnosis. The 4th patient, a 48-year-old woman, had Loeys-Dietz syndrome and had already undergone surgery for an aortic false aneurysm arising from the right coronary ostium suture line. Twenty-six months after that operation, echocardiography revealed an aortic false aneurysm at the proximal composite-valve-graft suture line. She declined further surgery and underwent yearly echocardiographic examination. At 37 months after diagnosis, the maximal diameter of the aneurysm was stable (17 mm) and she was asymptomatic.

Fig. 2 Graph shows survival after reoperation.

Discussion

Since the late 1990s, investigators have reported acceptable in-hospital mortality rates and satisfactory midterm outcomes in patients operated on for aortic false aneurysm (Table V 1,4–6,8–11). These experiences enabled determination of the most successful strategies for chest reentry.4,5,7,9,12

TABLE V. Early Deaths Reported after Reoperation for Postsurgical Aortic False Aneurysm

Patients with aortic false aneurysm can present with chest pain, dyspnea, and fever, and less frequently with mass-effect symptoms or erosion of surrounding structures.^1,5,9 Asymptomatic patients can be diagnosed with false aneurysm during routine monitoring and several years after the prior operation.4,5,7–9 This was confirmed in our cohort, in which 6 patients (24%) underwent diagnosis and reoperation 10 years after their previous surgical procedures. These findings justify long-term monitoring after aortic surgery, especially in the presence of recognized risk factors for aortic false-aneurysm development: previous aortic dissection, inherited connective-tissue disorders, or postoperative graft infection, sepsis, or mediastinitis.1,4,7–9,13 The use of biological glues at the suture lines is reportedly a chief cause of aortic-wall disruption^10,14; however, the cautious use of albumin glutaraldehyde glue has been shown to be safe and advisable.¹⁵

Infection is the most threatening condition, because of systemic involvement and the frailty of tissues. Previously, infection was reported to be the main cause of aortic false aneurysm in a widely variable number of patients, from 10% to 75%.1,4,5,7,8,16 This great variability probably arises from different definitions of infection as a cause: prior postoperative febrile status, mediastinitis, endocarditis, or septic status at reoperation. Furthermore, positive blood cultures, tissue cultures, or both were described in half or fewer of these patients (30%–50%).1,5,6,8 We have described 7 cases of patients who presented with infective postsurgical aortic false aneurysm. The diagnosis was confirmed by intraoperative findings and supported by preoperative positive blood cultures in 5 patients (with concordant tissue cultures in 2 cases) and a reasonable time correlation between systemic or sternal-wound infection and false-aneurysm diagnosis. Of note, evaluations with use of CT, positron emission tomography, or echocardiography were performed in 6 of 7 patients soon after the appearance of fever and signs of systemic inflammation, but these methods did not detect an aortic false aneurysm—thus revealing the pathogenic role of infection in suture-line disruption and false-aneurysm development. The prior postoperative history of these patients was characterized either by early-onset fever and sternal-wound complication necessitating antibiotic therapy, or by sepsis after pulmonary infection or subsequent invasive medical procedures (such as chronic dialysis or abdominal surgery). Although such occurrences may not be unusual during a postoperative course, early symptoms and signs of inflammation should arouse suspicion of systemic infection. If infection is confirmed by positive blood or tissue cultures, targeted antibiotic therapy for 4 to 6 weeks should be started promptly.

The natural history of aortic false aneurysm is still not well defined,^17,18 so the mere presence of that lesion, regardless of size, has been considered an indication for surgical repair.^4,5,9

We monitored 4 patients, all asymptomatic, who did not undergo reoperation (in one case, because of generally poor clinical condition). The follow-up time has been relatively short, and only 2 patients agreed to further imaging evaluations. In the first, during a 37-month period, imaging showed an almost unchanged maximal diameter of a false aneurysm arising from the proximal suture line of a composite valve graft; in the other patient, routine CT revealed an 8-mm increase in a false aneurysm arising from the left coronary ostium. These findings could suggest that a conservative approach be taken in asymptomatic patients with a small aortic false aneurysm; however, the evolution of the lesion is unpredictable, and late rupture or related sequelae could indicate the need for an emergent operation with unacceptable operative risk. In addition to symptomatic patients in whom reoperation should not be delayed, all asymptomatic patients diagnosed with aortic false aneurysm should be informed of the possible life-threatening evolution, and surgical options should be discussed with those in whom surgery would be appropriate.

In regard to repair techniques, isolated direct closure of the lesion's neck was performed in 15 patients (63%); accordingly, our rate of extensive repair with aortic-graft replacement is much lower than that reported in studies with larger populations.^4-6,9 Direct closure is not the optimal solution in uninfected patients because of the fragility of the suture-line tissue.⁹ Three of our patients had recurrent aortic false aneurysm after a simple repair. Similar findings had already been reported by Katsumata and colleagues¹ and Villavicencio and associates.⁶ However, at reoperation, patients' conditions need to be evaluated carefully, and closure of the aneurysm might be the only appropriate life-saving procedure in severely ill patients.

The opportunity to avoid open surgery is appealing, especially in patients who present in critical condition preoperatively. Percutaneous stent-graft placement, device occluder implantation, and coil embolization have been proposed for the treatment of false aneurysm of the thoracic aorta.^19–21 Endovascular techniques have some limitations, depending on the location of the false aneurysm and the size of the communication in the tear. Stent-grafts require adequate landing zones and might not be a safe option in proximity to the coronary ostia and supra-aortic vessels. Coil embolization could be effective in small aortic false aneurysms with narrow necks; however, reports of these procedures are anecdotal.²² Occluder devices could be used more extensively, but the absence of firm tissue, especially in infective lesions, increases the risk of device migration and embolization and the possibility of residual leak. The results reported in case reports and small case series are inconsistent with a cumulative intraprocedural success rate of about 86% (12 of 14 patients).²⁰ This finding does not include postoperative sequelae, such as device dislodgment or persistent flow in aortic false-aneurysm chambers; furthermore, the follow-up data are sparse. The effectiveness and safety of transcatheter procedures are still not optimal, so surgical repair has to be considered the procedure of choice for treating false aneurysms in patients who present in acceptable general condition. Infective false aneurysms suggest higher-risk conditions, especially in association with sepsis. Less invasive treatment might be advisable for these patients; however, the necessity of complete tissue débridement and extensive repair are the cornerstone in controlling infective lesions and avoiding recurrence.

In summary, aortic false aneurysm occurs infrequently after cardiovascular surgery. Its development and growth can be silent, and routine monitoring should be suggested to all patients who have undergone aortic surgery. This policy is crucial in the presence of aortic-wall pathologic conditions, in patients who have infections in the early postoperative period, and in patients who have recurrent or persistent signs of active inflammation. We think that surgery should be proposed to asymptomatic patients if clinical conditions permit, and that radical aortic-graft replacement is preferable to simple repair because of the possible recurrence of postsurgical aortic false aneurysm.