Pseudoaneurysm of the ascending aorta: case report of a donor-derived Pseudomonas infection in a heart transplant recipient

A 67-year-old man who had undergone orthotopic HTX 5 months before was admitted to our clinic for a surveillance endomyocardial biopsy (EMB) in perfect physical condition and asymptomatic. There was no history of fever episodes, other symptoms of infection, dyspnea, chest pain or malaise.

His medical history is significant for hypertension and chronic renal failure, the etiology of end stage heart failure was dilated cardiomyopathy with non-significant coronary stenosis. Brain death of the 31-year-old donor developed after a successful reanimation from a respiratory and cardiac arrest which was caused by an epiglottic abscess. The donor was septic with fever and high procalcitonin level (maximum 16 ng/ml). Cultures of the abscess grew Klebsiella aerogenes, Enterococcus faecalis, Staphylococcus aureus, Hafnia alvei, Finegoldia magna, Prevotella bivia and Prevotella oris. Chest x-ray and ultrasound showed right sided basal pneumonia. Microbiological examination of bronchoalveolar lavage fluid revealed the presence of Candida kefyr and multi-sensitive P. aeruginosa (results were validated on the day after transplantation). Donor received initial ceftriaxone therapy for 6 days (2000 mg once daily) that was changed to imipenem/cilastatin (500 mg four times daily), given for the last 24 h before donation.

Immunosuppression of the patient consisted induction therapy (3-day course of antithymocyte globulin and high-dose methylprednisolon) and triple maintenance immunosuppressive regimen including methylprednisolone (8 mg once daily), tacrolimus (aiming a trough level of 10–15 ng/ml in the first 3 months, then 8–10 ng/ml) and mycophenolic acid (720 mg twice daily). Perioperative prophylaxis considering the microbiology culture results of donor consisted of meropenem (1000 mg three times daily) and vancomycin (1000 mg twice daily), given for 48 h. The postoperative course was uncomplicated. Transthoracic echocardiographies (TTE) revealed good graft function with normal estimated pulmonary artery systolic pressure. No rejection episodes could be found with surveillance endomyocardial biopsies.

Retrospectively, outcomes of other transplanted organs were interrogated from Eurotransplant. Liver, both kidneys, vascular homografts and connective tissue were explanted from the same donor. Transport fluid of the right kidney grew Pseudomonas, therefore the recipient of this organ received piperacillin/tazobactam prophylaxis. Preservation fluids of other organs were not cultured. Neither the recipient of the left kidney, nor liver recipient received any anti-Pseudomonas prophylaxis. No donor-derived infection was reported after transplantation of left and right kidneys, liver and connective tissue. Vascular homografts were discarded for safety reasons.

At the beginning of June, the patient was scheduled for a regular EMB procedure. He presented with no symptoms except of a gradual weight loss of 15 kg (19% of his initial body weight) during 4 months. Physical examination was unrevealing. His blood pressure had been in target range for several weeks. No fever or subfebrility was detected.

Routine lab tests showed normal white blood cell count (8,9 G/l) with 87% neutrophyl granulocytes and a remarkable C-reactive protein (CRP) elevation showing an increasing tendency in the previous two months (7–24–31–57 mg/l). In addition, normocyter anemia (hemoglobin 104 g/l, hematocrit 33%) and impaired kidney function (glomerular filtration rate 39 ml/min, creatinin 155 µmol/l) was detected. Urinanalysis excluded pyuria or bacteruria. SARS-CoV-2 polymerase chain reaction test was negative.

TTE showed good graft function without any relevant abnormalities. Histological analysis of the EMB showed no rejection. Nor chest x-ray, neither abdominal sonography showed any relevant abnormalities. To identify the source of inflammation, a chest and abdominal computed tomographic (CT) scan was performed. This revealed a large, irregular, saccular dilatation of the tubular portion of ascending aorta with a maximum diameter of 90 mm (Fig. 1a, b).

Based on chest CT findings, an urgent surgical intervention was performed on the following day. Before performing median resternotomy, the left femoral artery was canulated through an 8 mm dacron vascular prosthesis for arterial line of cardiopulmonary bypass (CPB), to ensure the safety of patient in case of a pseudoaneurysm rupture. Myocardium protection was provided by antegrade Custodiol cardioplegia. After aortic crossclamp, the aortic pseudoaneurysm (Fig. 2a) was opened. We identified the rupture of the former aortic polipropilene running suture (Fig. 2b), which could be the basis for the pseudoaneurysm formation between the donor and the recipient aorta. The tissue quality of both donor and recipient aorta seemed to be normal macroscopically. However, the tissues where the pseudoaneurysm wall attached to the donor aortic wall contained purulent-like debris, this was sent for microbiology examination. We resected the pseudoaneurym thoroughly and performed an aorto-aortic interposition between the recipient’s distal ascendent aorta and donor’s sinotubular junction with a 28 mm dacron vascular prosthesis (Fig. 2c). CPB time was 78 min, aortic cross clamp time was 48 min.

The patient recovered from surgery uneventfully. TTE showed unchanged graft function. No decline in renal function was detected.

The patient received 18 days of intravenous treatment of ceftazidime (2000 mg three times daily) followed by 7 months of oral ciprofloxacin (500 mg twice daily) from the day of discharge. The targeted antibiotic therapy resulted in significant decrease in CRP level.

In the early postoperative period mycophenolic acid therapy was transiently stopped and reinitiated in a reduced dose when inflammatory markers decreased. Tacrolimus and steroid regimen was maintained.

At follow-up examinations the patient was doing well without fever, TTE-s showed no abnormalities and CRP level remained normal. Blood pressure could be kept in target range. EMB-s showed no sign of rejection.

19 days and 7.5 months after the surgery chest CT angiograms showed intact interposition graft of the ascending aorta with no sign of recurrent aortic pseudoaneurysm (Fig. 3). Based on this finding and the continuously normal inflammatory markers of the patient, we decided to discontinue the oral ciprofloxacin therapy almost 8 months after the operation.

At his latest follow-up one year after the operation the patient is still asymptomatic with normal inflammatory markers.