18-Fluorodeoxyglucose positron emission tomography in the diagnosis of prosthetic aortic graft infection: the difference between open and endovascular repair

OBJECTIVES

18-Fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) has been reported as useful for diagnosing aortic graft infection. However, 18F-FDG uptake may depend upon various factors including open versus endovascular repair and time from surgery. We aimed to elucidate the factors influencing its uptake and the diagnostic value of 18F-FDG PET/CT after open and endovascular repair.

METHODS

Hospital database of PET/CT (N = 14 490) and our departmental database were cross-checked to identify those who underwent 18F-FDG PET/CT after aortic repair. Patient's data were retrieved from the chart. Images were reviewed by 2 nuclear medicine specialists in consensus, and the presence of increased 18F-FDG uptake was recorded. The maximum standardized uptake value (SUV max) was measured.

RESULTS

Among the 1112 patients who underwent aortic repair between 2011 and 2022, 71 patients were identified. Eighteen patients underwent 18F-FDG PET/CT for suspected graft infection and the remaining 53 patients for other purposes (malignancy, etc.). Fourteen patients were treated as aortic graft infection. They had significantly higher SUV max than those without graft infection [mean 8.64 (standard deviation 2.78) vs 3.40 (standard deviation 0.84); P < 0.01]. In the non-infected grafts, SUV max was higher early after open surgical repair, while it remained low after endovascular repair.

CONCLUSIONS

After endovascular aortic repair, a constant cut-off value of 'SUV max = 4.5' seems appropriate for diagnosing graft infection, since it remains low and stable from the early postoperative period. After open surgical repair, it seems acceptable to have 'stepwise cut-off value' depending on the time from surgery.

Successful Treatment of Recurrent Thoracic Aortic Prosthetic Graft Infection after Omentopexy by Free-latissimus Dorsi and Rectus Abdominis Muscle Flap

A 50-year-old patient, who underwent total aortic arch replacement for acute type A aortic dissection, developed recurrent thoracic prosthetic graft infection after omentopexy for the treatment of initial postoperative graft infection of ascending aorta and transverse aortic arch. We report a successful treatment of the disastrous complication by covering the prosthetic graft with free latissimus dorsi muscle flap coupled with pedicled rectus abdominis myocutaneous flap for the reduction of mediastinal dead space, following the surgical disinfection with partial graft reconstruction.

Management and Outcomes of Proximal Aortic Graft Infection: A Systematic Review

OBJECTIVE

Proximal aortic graft infection (PAGI) is a rare but often fatal postoperative complication. Its management often relied on surgical preferences and resource availability of each centre, until the recent unifying guidelines published by the European Society for Vascular Surgery (ESVS). This paper aimed to amalgamate the published experience in managing PAGI and their outcomes.

METHODS

PubMed, Scopus and Cochrane Library databases were searched systematically. All primary studies besides single-patient case reports were included. Data extracted included study and patient characteristics, type of index surgery, type of microorganisms involved, definitive treatment modality, and any outcome measures reported.

RESULTS

Of the 20 studies included, 157 of the 290 PAGI patients underwent complete graft explantation and replacement, 106 underwent graft-preservation interventions (debridement and/or irrigation), and 25 had antibiotics alone. Adjunctive interventions included graft coverage, vacuum-assisted closure, use of infection-resistant graft materials, and lifelong suppressive therapy. In-hospital mortality was 20.8% (n=60), with postoperative sepsis and multiorgan failure (n=24) being the most common cause. Recurrent infection occurred in 10 post-discharge patients. Post-discharge mortality rate was 11.4% (n=33), with cardiac complications and stroke being the most common cause in surgically-treated and medically-treated patients, respectively.

CONCLUSIONS

Given the risk of mortality, the management approach of PAGI highly depends on the fitness of the patient. We believe that early referral to specialised aortic centres is essential to plan for optimal management strategies and improve patient outcomes. Further studies are also required to parse out the most effective adjunctive interventions to maximise patient outcomes.

Infections of the aorta

Infection of the aorta continues to be a clinical challenge with high morbidity and mortality. The incidence varies between 0.6 and 2.6%. There has been a steady increase in graft infections, especially endograft infections, due to increased procedures (0.2 to 5%). Staphylococcus species remains the most common organism; however, gram-negative and rare causative agents are also reported. The clinical presentation can be very diverse and a high degree of suspicion is necessary to diagnose them. Sometimes, they may present as an emergency with rupture or fistulation. Diagnosis is based on a triad of clinical features, microbial cultures and imaging. Culture-specific antibiotics are mandatory during the entire course, but seldom cure alone. Surgical management remains the standard of care and involves an integrated approach involving debridement, reconstruction and use of adjuncts. Various aortic substitutes have been described with advantages and limitations. Pericardial tube grafts have emerged as a good option. Endo-vascular options are practiced mostly as a bridge to definitive surgery. A small role for conservative management is described. Aortic fistulation to the gut and airway carries a very high mortality. There are no large series in the literature to define guideline-directed treatment and most often it is a customized solution. The 30-day mortality remains close to 30%. Outcomes depend on multiple factors including patient's age, the timing of presentation, diagnosis, causative organism, host status and the treatment strategy adopted.

[Multi-component multi-stage treatment of a patient with infection of thoracic aorta prosthesis, deep sternal wound infection and soft tissue deficit of the chest]

We report a comorbid patient after redo Frozen Elephant Trunk procedure followed by recurrent infection of thoracic aortic prosthesis, deep sternal wound infection and extensive soft tissue defect. Closure with skin-muscle thoracodorsal flap and graft-sparing technique with omentoplasty is an alternative to total graft replacement for thoracic aortic graft infection in comorbid patients with concomitant extensive defect of the chest wall or recurrent infection in early postoperative period.

Incidence and Surgical Outcomes of Patients With Native and Prosthetic Aortic Valve Endocarditis

BACKGROUND

The aim of this study was to retrospectively evaluate the incidence and surgical outcomes of patients with native infective endocarditis (IE) and prosthetic aortic valve endocarditis (PVE) over the past decade at a single institution.

METHODS

Between January 2005 and December 2015, 289 patients (mean age, 63.3 ± 14.2 years) suffering from native IE (n = 186) and PVE (n = 103) of the aortic valve underwent surgical procedures. Perioperative data were acquired retrospectively for statistical analysis.

RESULTS

During the study period the mean incidence of endocarditis increased from 22.0 ± 4.2 (2005-2009) to 29.8 ± 10.1 (2010-2015) cases per year. In-hospital mortality was significantly increased in PVE (22.3%) versus IE (9.1%) patients (P < .001). In elective cases in-hospital mortality between the 2 groups was comparable (2.2% vs 4.6%; P = .288). Multivariate analysis identified urgent surgery (odds ratio [OR], 6.461; 95% CI, 1.941-21.509; P = .002), mitral regurgitation II (OR, 4.230; 95% CI, 1.249-14.331; P = .021), previous homograft operation (OR, 66.096; 95% CI, 2.369-1844.272; P = .0.14), and left ventricular ejection fraction < 40% (OR, 8.267; 95% CI, 1.931-35.388; P = .004) as independent risk factors for in-hospital mortality, whereas pathogen identification by preoperative blood cultures (OR, .228; 95% CI, 0.063-0.817; P = .023) was found to be independently protective.

CONCLUSIONS

Surgery for native IE and PVE of the aortic valve may be performed with satisfactorily results at experienced cardiac surgical centers. In comparison PVE patients suffer from a more than twice as high in-hospital mortality, more postoperative complications, and inferior long-term survival. However preoperative identification of causative pathogens in IE and PVE allows for improved in-hospital survival.

Influence of Cryopreservation on Structural, Chemical, and Immunoenzymatic Properties of Aortic Valve Allografts

OBJECTIVES

The problems in preparing (including cryopreservation) and implanting aortic valve allografts (AVAs) is widely elaborated, but some issues need explanation.

MATERIAL AND METHODS

Twenty AVAs cryopreserved in dimethylsulphoxide/RPMI solution under -160°C for 1-15 years and 3 controls stored at +4°C up to 2 weeks, from 19 male and 4 female donors, aged 20-51, ±30.8 years, were examined using light (LM), digital (DM), and scanning electron microscopy (SEM), energy dispersion X-ray spectroscopy (EDS), and enzyme-linked immunosorbent assay immunoenzymatic tests (PECAM1, CD34).

RESULTS

All AVAs were macroscopically correct. LM revealed normal structure of leaflets but massive endothelial decellularization (±59 cells remained on the surface of 5 mm scraps). DM and SEM demonstrated generally normal collagen structures, but local alterations, probably influenced by freezing-thawing (gaps, separated plates) or being initial phase of native degeneration (grains). EDS detected a little elevated calcium amount in 1 specimen only. The mean PECAM1 and CD34 concentrations were at similar low level in all probes.

CONCLUSIONS

Fresh and cryopreservation technologies did not significantly influence the basic properties of AVA leaflets; however, massive endothelial decellularization was present in both groups. Therefore, no endocardial cell activity nor signs of inflammation were observed. These results were independent of donors' age and sex, processing technology, and time of storage of cryopreserved AVAs.

A Loeys-Dietz patient with a transatlantic odyssey: repeated aortic root surgery ending with a huge left main coronary aneurysm

We present a patient who required several aortic root procedures. Finally, a huge aneurysm of the left main coronary artery required emergency surgery after a failed transcatheter procedure.

Management of early graft infections in the ascending aorta and aortic arch: a comparison between graft replacement and graft preservation techniques

OBJECTIVES

Treatment of infected thoracic aortic grafts is associated with considerable morbidity and mortality. The replacement of an infected graft is an effective strategy, yet a complex surgical endeavour, especially if the aortic root or aortic arch is involved. In situ graft-sparing surgical therapy with continuous mediastinal irrigation after surgical debridement might offer an alternative in the management of early graft infections in the thoracic aorta.

METHODS

Between 1996 and August 2015, 25 patients were treated in our institution for early graft infection after thoracic aortic surgery via sternotomy. In 11 patients, the infected prosthesis was replaced by a cryopreserved homograft or a biological valved pericardial xenograft. In 14 patients, an attempt to salvage the graft was made by resternotomy, aggressive debridement and subsequent continuous mediastinal antibiotic irrigation over a course of 2 weeks, accompanied by systemic antibiotic therapy.

RESULTS

In-hospital mortality was comparable (replacement group: 2/11 = 18%, graft-sparing group: 2/14 = 14%, P = ns). The time interval from the initial surgery was significantly shorter in the graft-sparing group (replacement group: 165 days [range 95-300 days] and graft-sparing group: 24 days [range 15-93 days], P = 0.004]. Two patients (14%), who were treated with the graft-sparing approach >100 days after the initial surgery, were retreated for infection, and 1 due to an intra-aortic infection of an aortic arch hybrid stent graft was not amenable to external irrigation (median follow-up: 1.5 years [range 1.1-2.1 years]). One patient in the replacement group (9%) was reoperated on due to homograft degeneration (median follow-up: 6.0 years [3.0-8.9 years]).

CONCLUSIONS

In situ graft-sparing surgical therapy is safe and effective if diagnosis and treatment of aortic graft infection is initiated promptly and aggressively (ideally <1 month post-surgery). Our method produces good midterm results (3 years). For aortic graft infections that become clinically apparent >3-6 months after surgery, replacement of grafts with biological conduits (homografts or pericardial xenografts) most likely remains the best treatment option.

Resistance to infection of long-term cryopreserved human aortic valve allografts

OBJECTIVE

To analyze the in vitro antimicrobial activity of 3 antibiotic regimens (group A, gentamicin-piperacillin-vancomycin-metronidazole-amphotericin B; group B, gentamicin-piperacillin-flucloxacillin-metronidazole-amphotericin B; and group C, meropenem-vancomycin-tobramycin-colistin-amphotericin B) used in the processing of cryopreserved human ascending aortic tissue and aortic valves against Staphylococcus epidermidis and Staphylococcus aureus. The results were additionally compared with the infection resistance of cryopreserved ascending aortic tissue against Escherichia coli and Pseudomonas aeruginosa.

MATERIALS

Each of 10 cryopreserved human allografts (CHAs) was divided into 25 pieces (separating aortic wall and valve). Eighteen segments were microbiologically tested, and 7 pieces underwent scanning electron microscopy. A bacterial solution (4 mL; optical density, 0.20 ± 0.02) was used for contamination. After incubation, the optical density of the solution was measured. CHAs underwent sonication to release viable adherent bacteria. The number of attached bacteria was quantified by the colony forming units per square centimeter of CHA surface.

RESULTS

Antibiotic regimen groups B and C were more efficient than group A in eradicating gram-positive organisms adherent to the aortic wall (P < .001). Group C showed enhanced resistance against E coli compared with group A or B (P < .001), whereas group B appeared to be more effective against P aeruginosa (P < .001). With reference to each antibiotic regimen, ascending aortic tissue showed significantly less bacterial contamination with staphylococcal bacteria than valve grafts (P ≤ .01).

CONCLUSIONS

CHAs possess antibacterial activity despite long-term storage over 5 years. Antibiotic combinations applied during CHA processing have a significant influence on their infection resistance. Ascending aortic tissue shows a significantly enhanced bacterial resistance against staphylococcal bacteria compared with aortic valves.

Successful surgical in situ treatment of prosthetic graft infection by staged procedure after Bentall operation and total aortic arch replacement

We report a case of a 29-year-old Marfan patient who developed prosthetic graft infection 10 months after Bentall operation and successive replacement of the remaining ascending aorta and the entire aortic arch for acute aortic dissection. Instead of an aggressive high-risk aortic redo procedure with removal and replacement of the infected prosthetic graft we elected a staged graft-sparing surgical approach. After 18 months of close follow-up the patient is in good condition and free from infectious sequela. This case and our review of the literature suggest that open extensive disinfection followed by tissue flap coverage is highly effective in controlling thoracic aortic prosthetic graft infection and may be considered as first-line treatment in such high-risk aortic arch redo patients.