Postcardiotomy extracorporeal membrane oxygenation in a patient with Austrian syndrome

Abstract

A 43-year-old man with Austrian syndrome, the triad of infective endocarditis (IE), pneumonia and meningitis caused by Streptococcus pneumoniae, underwent emergency aortic and mitral valve replacement and closure of an aortic root abscess. Postoperatively, he required mechanical circulatory support with veno-arterial extracorporeal membrane oxygenation and an intra-aortic balloon pump. Several days after surgery, new mitral and aortic paraprosthetic leaks (PPLs) developed. These were managed conservatively, initially, but eventually required percutaneous closure 6 weeks after the initial operation. This has enabled the patient to recover to independent mobility, 20 weeks after the operation. This case illustrates a rare clinical syndrome and the devastating impact of IE. Moreover, it illustrates the successful application of extracorporeal membrane oxygenation in postcardiotomy cardiac failure and the successful treatment of PPL in a patient unfit for redo surgery.

Background

Robert Austrian first described the affinity of Streptococcus pneumoniae to the aortic valve and the simultaneous presence of meningitis in 1957.¹ S. pneumoniae is the causative organism in less than 3% of patients with infective endocarditis (IE). It is a virulent organism and the condition often runs a fulminant course with rapid valvular destruction, prompting early surgical intervention. Thirty per cent of cases are also associated with meningitis.² Austrian syndrome has an incidence of 1.2% among patients with IE and is associated with a high mortality.³

Extracorporeal membrane oxygenation (ECMO) was first developed in the 1970s. It provides prolonged respiratory and cardiac support in patients of life-threatening pulmonary and/or cardiac failure, when no other treatment has been or is likely to be successful. It affords a patient time to recover their cardiac function or become suitable for a durable ventricular assist device or heart transplantation. Outcomes are related to the indications for commencing therapy.

We wish to share our experience of this case as it illustrates a couple of salient points. First, the diagnosis of IE should always be sought. The peripheral stigmata of IE typically develop late, so patients with meningitis and pneumonia, or ongoing signs of sepsis, should have a daily review and clinical examination, actively seeking signs of IE. Had the diagnosis of IE been missed in this patient, he would have died. Second, this patient survived due to the intrepid efforts of a clinical team for a patient, others may have considered inoperable. At the time of referral to our unit, he was profoundly septic, requiring an infusion of norepinephrine (0.5 µg/kg/min) to maintain a mean arterial pressure (MAP) of 61 mm Hg.

Case presentation

A 43-year-old man presented to the local hospital with acute onset of confusion on the background of 3 days of fever, sweating and dyspnoea. He was known to have a bicuspid aortic valve. He had previously suffered from recurrent gallstone pancreatitis requiring biliary stenting and was being evaluated for a distal pancreatectomy. On presentation, he was in septic shock and therefore admitted to the intensive care unit (ICU).

The source of sepsis was not evident on clinical examination. CT of the chest, abdomen and pelvis demonstrated mucosal thickening of the sigmoid colon only. His ongoing confusion prompted a CT of the head, which did not demonstrate any abnormality. Examination of his cerebrospinal fluid (CSF) demonstrated gram-positive cocci. He was treated for presumed pneumococcal sepsis and meningitis with ceftriaxone and acyclovir. Due to severe agitation and confusion, he was sedated and mechanically ventilated. After 6 days, he was successfully weaned from mechanical ventilation. On day 8, he suffered an unheralded cardiorespiratory arrest. His ECG demonstrated new left bundle branch block (LBBB). Repeat transoesophageal echocardiography (TOE) showed new vegetations on the mitral and aortic valves, an aortic root abscess and impaired left ventricular function. Antimicrobial therapy was escalated to meropenem.

With a diagnosis of Austrian syndrome and acute severe aortic valve regurgitation, the patient was referred to our unit for emergency surgery.

Investigations

On admission to the local hospital, the patient was feverish (38.2°C) and tachycardic (heart rate 115 beats/min) with a reduced Glasgow Coma Score of 12. His white cell count (WCC) was 17×10⁹/L, C-reactive protein (CRP) 360 mg/L and arterial lactate 5.6 mmol/L. Lumbar puncture demonstrated an elevated opening pressure (27 mm CSF) and culture of his CSF demonstrated the presence of penicillin-resistant S. pneumoniae. Pneumococcal antigens were detected in the patient’s urine. On admission, ECG showed atrial fibrillation with a rapid ventricular response rate, but no higher order conduction deficit.

Following the cardiorespiratory arrest, the ECG showed new LBBB. A further TOE revealed an aortic root abscess, explaining the conduction defect, along with a large vegetation on the anterior mitral valve leaflet (AMVL), aortic valve vegetations with valvular destruction, causing valvular regurgitation, and left ventricular volume overload and impaired systolic function. The patient’s serum troponin T rose from 52 to 842 ng/L, prompting a CT coronary angiogram. This showed unobstructed coronary arteries, but revealed left lower lobe consolidation and partial lobar collapse.

Treatment

When the patient arrived on our ICU, he required an infusion of norepinephrine (0.5 µg/kg/hour) to maintain a MAP of 61 mm Hg. He was oligoanuric. Infusions of the inodilator miltrinoe (0.2 µg/kg/min) and vasoconstrictor vasopressin (0.04 units/min) were commenced and he was scheduled for emergency surgery.

He underwent a mechanical mitral valve and mechanical aortic valve replacement and closure of the left ventricular outflow tract (LVOT)/aortic root abscess with a bovine pericardial patch. Intraoperative findings included an extensive fibrinous/purulent peel covering the heart. There was a large vegetation on the AMVL and vegetations on the aortic valve cusps with a perforation of the left coronary cusp (LCC). There was also a 5×4 cm abscess extending from the LVOT to beyond the LCC, causing destruction of the aortic valve annulus. Remnants of the abscess could be seen from the back wall of the aorta. Due to the size of the vegetation on the AMVL, the mitral valve could not be spared and was excised along with its chordae. Bilateral pleural effusions (1000 mL) were also drained. The duration of cardiopulmonary bypass (CPB) and aortic cross clamping was prolonged (222 and 173 min, respectively). It was not possible to separate the patient from CPB despite support with an intra-aortic balloon pump (IABP), milrinone, norepinephrine and vasopressin. The decision was therefore made to convert CPB to veno-arterial extracorporeal membrane oxygenation (VA-ECMO) using the same cannulae. The patient returned to the ICU with an open chest (figure 1).

Figure 1.

CXR showing the central cannulation of the VA-ECMO; (a) aortic pipe, (b) two-stage venous pipe. VA-ECMO, veno-arterial extracorporeal membrane oxygenation.

Outcome and follow-up

The antimicrobial therapy was a combination of meropenem, vancomycin and rifampicin. On the fourth postoperative day, his WCC was normal, his CRP improved and he required less vasoactive drugs. He successfully decannulated from ECMO on the sixth postoperative day. Two days later, it was possible to remove the IABP and close the chest.

The postoperative period was complicated by watershed cerebral infarcts with haemorrhagic transformation, polycystic lung lesions, likely from septic emboli, and colonisation of his sputum with candida species and a multidrug-resistant Pseudomonas aeruginosa. The patient required a tracheostomy to facilitate weaning from mechanical ventilation. The tracheostomy was removed 37 days after surgery. He had a significant ICU-acquired weakness that improved with intensive physical rehabilitation. He also had impaired vision following bilateral cerebral infarctions.

A contributory factor to the prolonged postoperative recovery was the early development of a paraprosthetic leak (PPL), initially of the aortic valve, but later of both valves. Due to the patient’s frailty, this was managed with pharmacological vasodilation. On the 53rd postoperative day, the patient was transferred to the local hospital for continued rehabilitation. At this time he was asymptomatic. Three weeks later, however, he was readmitted to our unit with heart failure resistant to medical therapy. Due to the patient’s poor clinical status, he was not a candidate for redo cardiac surgery. After a multidisciplinary discussion, the decision was therefore made to attempt to occlude the PPL with a percutaneous device. Eleven days after readmission, the mitral PPL was successfully occluded using a percutaneous technique (figure 2). Nine days after this procedure, the patient was once again repatriated to the local hospital for ongoing rehabilitation.

Figure 2.

Fluoroscopy of the two prosthetic valves (a) aortic, (b) mitral) and the Amplatzer duct occluder (c).

The patient was eventually discharged home 16 weeks after his presentation with help from the comminuty support team.

He is now independently mobile, but still has blurred vision and diplopia, for which he is registered blind.

Discussion

Surgical intervention in IE is indicated for acute valvular regurgitation or if there are signs of heart failure.² The mitral valve is spared where possible, when the vegetations can be removed with preservation, or the satisfactory repair of, the mitral valve apparatus. When this is not possible, the valve is replaced.² Pneumococcal endocarditis is associated with a mortality of 32% when managed surgically. This compares to the 60% mortality of patients who receive medical care alone, despite the administration of appropriate antibiotics.⁴ These numbers highlight the virulence of the bacterium and the need for early diagnosis and combined intervention.

The diagnosis of endocarditis caused by S. pneumoniae is often delayed due to the lack of the typical stigmata of IE and the late occurrence of pathological murmurs.⁵ Moreover, the coexistence of other foci of infection may distract clinicians from establishing the diagnosis. Therefore, it is paramount to maintain a high index of suspicion and to regularly re-examine the patient thoroughly. Transthoracic echo (TTE) is recommended as firstline imaging in IE, but TOE should be performed in all patients with a clinical suspicion of IE with a negative or non-diagnostic TTE.² Our patient did not display the classical signs of IE until he suffered a cardiac arrest. At this point, ECG showed new LBBB and TOE showed valvular vegetations.

Postcardiotomy VA-ECMO support is controversial, with critics citing cost and unproven outcomes as the rate-limiting factors to its wider application. Loforte et al presented a case series of 228 consecutive patients treated with ECMO for refractory cardiogenic shock of which 118 were postcardiotomy. One hundred and twenty-two patients (53.5%) were successfully discharged.⁶ In this case, since it was not possible to separate this patient from CPB, VA-ECMO undoubtedly prevented his death in the operating theatre.

VA-ECMO is neither available in all cardiac surgery units, nor is it suitable for all patients. Key to treatment of Austrian syndrome is early diagnosis and treatment with antibiotics as well as surgical valve repair or replacement, as combined therapy almost halves mortality. Medical optimisation is paramount in patients temporarily unfit for surgery. In profoundly septic patients, a combination of vasopressor and inotropic support and the addition of IABP may be required depending on the patient’s haemodynamic status.

PPL is not uncommon after valve replacement surgery, with an incidence that varies depending on the case series, which valve is replaced, the type of prosthetic valve and the implantation technique. Incidence rates range from 2.5%⁷ to 47.6%,⁸ but the PPL is usually very small and of little clinical significance. Haemolysis should be excluded and symptoms of heart failure should be medically managed. Re-operation or percutaneous closure should be considered in patients where medical therapy fails.⁹

Learning points.

• In patients with an indolent clinical course as well as acute deterioration, the diagnosis of infective endocarditis (IE) should always be sought.

• Austrian syndrome is rare, but when pnuemonia and meningitis coexist, especially when caused by Streptococcus pneumoniae, IE should be sought.

• S. pneumoniae is a virulent bacterium and patients should therefore be treated with both medical and surgical therapy, where possible.

• Extracorporeal membrane oxygenation can rescue patients who are unable to separate from cardiopulmonary bypass. Its use should be considered in this setting.