There is Nothing More Invisible than the Obvious: A Case Summary and Literature Review

Abstract

Bioprosthetic valvular failure (BVF) is a pathological entity arising from a variety of conditions affecting prosthetic heart valves. It may present with an extremely varied pattern, and the identification of the exact etiology is vital to provide a prompt and adequate treatment. It is established that infective endocarditis mainly affects patients with intracardiac devices such as pacemakers or prosthetic valves, and it represents one of the principal mechanisms of BVF. Despite its high incidence, clinical presentations may be atypical, and a close monitoring is essential to prevent catastrophic consequences. We present the case of a partial valvular bioprosthesis detachment associated with a newly formed pseudoaneurysm due to a late infective endocarditis occurred after cardiac surgery, initially manifested with negative blood cultures and clinical findings. We also try to set up a literature review of the most common causes of valvular failure and pseudoaneurysm formation.

INTRODUCTION

Bioprosthetic valvular dysfunction is a complex entity comprising several conditions that may present as structural valve deterioration (SVD) and its clinical correlate, bioprosthetic valvular failure (BVF).[1] SVD is can be defined as “an acquired intrinsic bioprosthetic valve abnormality defined as deterioration of the leaflets or supporting structures resulting in thickening, calcification, tearing, or disruption of the prosthetic valve materials with eventual associated valve hemodynamic dysfunction, manifested as stenosis or regurgitation.”[2] It is related to primary valvular alterations and mostly develops in a long-term fashion with a pattern according to the features of each specific prosthesis. The most common pathogenic processes involved are calcification (particularly enhanced from the pretreatment with glutaraldehyde[3]) and leaflet degeneration, frequently leading to hemodynamic implications such as valvular stenosis, regurgitation, or both. Whereas BVF can be secondary to SVD, it could be also accounted for further etiologies such as endocarditis, leaflet thrombosis, and a group of heterogeneous conditions defined as “nonstructural valve dysfunction,” including prosthesis malposition, late embolization, and patient–prosthesis mismatch.[2,3,4,5,6,7,8,9,10] Endocarditis has a significant prevalence among patients with valvular prostheses, and perivalvular complications such as abscesses, pseudoaneurysms, and fistulae are eventualities leading to a higher mortality. The clinical picture of BVF due to infective endocarditis can be very diverse, ranging from acute or chronic decompensated heart failure to neurological and systemic embolic complications.[9] Among the complications associated with BVF, paravalvular pseudoaneurysms undoubtedly represent one of the most lethal. Despite being a known consequence of trauma or surgery, pseudoaneurysms recognize infective endocarditis as one of their main etiologies and the mitro-aortic fibrosa, located between the left coronary cusp and the anterior mitral leaflet, is one of the most common locations in the context of aortic valvular endocarditis. Indeed, their presence should prompt a close monitoring due to the fragile fibrotic avascular structure they are made of that predisposes them to complications such as fistula formation, expansion (with the possibility of coronary compression) thrombosis or even rupture with catastrophic consequences; cardiac surgery clearly represents the treatment of choice in these delicate circumstances.[11,12,13,14,15,16,17,18] Despite being a well-known cause of morbidity and mortality, valvular failure can provoke unexpected diagnostic and therapeutic challenges. We present the case of a partial valvular bioprosthesis detachment associated with a newly formed pseudoaneurysm due to an infective endocarditis following cardiac surgery, initially manifested with negative clinical and cultural laboratoristic findings.

CASE REPORT

A 74-year-old man was admitted to our institution 3 months after an aortic valvular replacement symptomatic for occipital headache associated with dyspnea and concomitant hypertensive peak. New-onset valvular regurgitation due to prosthesis detachment and pseudoaneurysm development was found. Whereas blood cultures and inflammatory indices tested negative, due to its delicate hemodynamic conditions, the patient was directed to the cardiac surgery department. During hospitalization, a diagnosis of Staphylococcus epidermidis endocarditis was established after a second set of blood cultures. A proper antibiotic therapy and a redo intervention were performed. After postoperative routinary hospitalization and guideline-directed antibiotic therapy, the patient recovered his daily living activities and was finally discharged.

Case presentation

A 74-year-old Caucasian male affected by diabetes mellitus, arterial hypertension, peripheral artery disease, and chronic obstructive pulmonary disease was admitted to our institution for occipital headache associated with dyspnea and concomitant hypertensive peak (noninvasive blood pressure: 200/100 mmHg). He was recently admitted for aortic valvular replacement due to severe aortic valve stenosis complicated by sternal wound dehiscence treated with Robicsek technique and intravenous antibiotics.[19] Postsurgery hospitalization was characterized by sternal dehiscence requiring prolonged antibiotic therapy. Admission electrocardiogram showed normal atrioventricular and intraventricular conduction with nonspecific ventricular repolarization abnormalities superimposable to a past examination. The patient showed no physical signs of congestion or pulmonary edema. Nevertheless, a diastolic murmur could be heard at Erb’s point, so a transthoracic echocardiography was performed in the emergency department revealing a severe aortic regurgitation secondary to a partial bioprosthesis detachment [Figure 1].

Figure 1.

Transthoracic echocardiogram showing aortic regurgitation

In order to obtain more information regarding valvular structure and the etiological mechanisms of such regurgitation, the patient was admitted to our cardiology unit. A transesophageal echocardiogram (TOE) was performed confirming a valvular detachment with a newly formed pouch located in the mitro-aortic membrane that was identified as a pseudoaneurysm [Figures 2 and 3, Videos 1 and 2].

Figure 2.

Transesophageal echocardiogram showing a pseudoaneurysm in the mitro-aortic continuity

Figure 3.

The same findings at a three-dimensional view transesophageal echocardiogram

According to his past clinical history, our first concern was to exclude an active infective endocarditis. Hematologic tests showed normal inflammatory indices with normal leukocyte count. No other clinical systemic signs of endocarditis could be found. Three sets of blood cultures were collected without identification of microbial foci. Considering these findings, we tried to exclude the possibility of a nonstructural valve dysfunction due to surgical failure, but this chance was dismissed after discovering a complete echocardiogram performed 3 weeks before admission, where normal biventricular ejection fraction and physiological bioprosthesis transvalvular gradients were reported. In order to evaluate further causes of prosthesis failure, we addressed the patient to the cardiac surgery department to perform a redo surgical aortic replacement. New blood cultures were collected, and a positivity for S. epidermidis was then revealed. An antibiotic-guided therapy was started, and surgery was finally performed. Surgical valvular replacement with pseudoaneurysm repair was successfully completed, and valvular fragment cultures confirmed an S. epidermidis infection. After a noncomplicated postoperative period and a 6-week guideline-directed antibiotic therapy with double confirmation of blood culture negativity, the patient was directed to a cardiac rehabilitation program witnessing a complete recovery.

DISCUSSION

Current literature reports endocarditis as one of the leading causes of valvular failure in patients undergoing aortic valve replacement.[8] Its mortality rate is undoubtedly high with an overall incidence of 20%–40%; the diagnostic suspect should be raised by the clinical presentation and echocardiography findings such as abscesses, vegetations, fistulae, or pseudoaneurysms.[9]

In most cases, patients report symptoms such as fatigue or fever, and despite the possibility of negative hemocultures, inflammatory indices such as leukocytosis or C-reactive protein tend to be positive. Furthermore, the development of a pseudoaneurysm is often related to the presence of an abscess that could not be detected in our patient. We speculate that prolonged antibiotic therapy administered after sternal dehiscence during the first hospitalization could have masked the classic TOE findings. Anecdotical case reports suggest percutaneous repair as a possible solution for the closure of pseudoaneurysm in some patients,[20] but the hemodynamic impact of the concomitant valvular detachment in our patient addressed the need of a more radical procedure. Valvular detachment is an infrequent complication of infective endocarditis, but it has been described in some isolated cases, with the direct involvement of the annular structures as its primary etiology.[21] In these circumstances, surgery is the only option capable of restoring a proper anatomy and, most importantly, a correct function of the valvular apparatus.

CONCLUSIONS

BVF is a fearsome and severe condition presenting with a wide spectrum of clinical presentation. Our experience highlights the need of a prompt diagnosis even in the context of atypical clinical scenarios. An early intervention might be crucial to preserve the patient’s hemodynamic equilibrium and avoid a systemic dissemination of microbial infection.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.