Novel imaging strategies for the detection of prosthetic heart valve obstruction and endocarditis

Multimodality Imaging Diagnosis in Infective Endocarditis

Imaging is an important tool in the diagnosis and management of infective endocarditis (IE). Echocardiography is an essential examination, especially in native valve endocarditis (NVE), but its diagnostic accuracy is reduced in prosthetic valve endocarditis (PVE). The diagnostic ability is superior for transoesophageal echocardiography (TEE), but a negative test cannot exclude PVE. Both transthoracic echocardiography (TTE) and TEE can provide normal or inconclusive findings in up to 30% of cases, especially in patients with prosthetic devices. New advanced non-invasive imaging tests are increasingly used in the diagnosis of IE. Nuclear medicine imaging techniques have demonstrated their superiority over TEE for the diagnosis of PVE and cardiac implantable electronic device infective endocarditis (CIED-IE). Cardiac computed tomography angiography imaging is useful in PVE cases with inconclusive TTE and TEE investigations and for the evaluation of paravalvular complications. In the present review, imaging tools are described with their values and limitations for improving diagnosis in NVE, PVE and CIED-IE. Current knowledge about multimodality imaging approaches in IE and imaging methods to assess the local and distant complications of IE is also reviewed. Furthermore, a potential diagnostic work-up for different clinical scenarios is described. However, further studies are essential for refining diagnostic and management approaches in infective endocarditis, addressing limitations and optimizing advanced imaging techniques across different clinical scenarios.

Diagnostic Value of Computed Tomography Angiography for Infective Endocarditis After Right Ventricle Outflow Tract Repair

Congenital heart disease patients with pulmonary valve replacement or right ventricle-pulmonary artery conduit have increased risk of pulmonary valve endocarditis. We present a 6-patient case series illustrating the diagnostic utility of computed tomography angiography to provide definitive visualization of pulmonary valve vegetation to aid in the diagnosis of endocarditis. (Level of Difficulty: Intermediate.).

Case Report: Culture-negative Prosthetic Valve Endocarditis

BACKGROUND

Prosthetic valve endocarditis can be difficult to diagnose and cause significant morbidity and mortality, especially when no culture data are available to guide therapy. Transthoracic and transesophageal echocardiograms, the studies of choice for initial endocarditis evaluation, can be less reliable due to artifact and post-surgical changes. Some less common forms of endocarditis may be difficult to culture and, due to their fastidious nature, may delay the identification of causative organisms. Given the lack of directed antimicrobial treatment, culturenegative prosthetic valve endocarditis is specifically difficult. A wide differential diagnosis is critical to make a timely diagnosis and initiate treatment.

CASE PRESENTATION

We present a case of a patient presenting with dyspnea which was found to have culture-negative endocarditis requiring mitral and aortic valve replacement that ultimately was complicated with culture-negative prosthetic valve endocarditis. Identifying a culprit organism made appropriate and timely antimicrobial treatment difficult, ultimately resulting in the patient dying from endocarditis complications.

CONCLUSION

A high index of suspicion is needed when managing infective endocarditis, especially when prosthetic valves are involved. Diagnostic accuracy of cultures and echocardiography may be reduced when dealing with prosthetic valve endocarditis; thus, alternative methods of diagnosis may be required to make a timely diagnosis of causative organisms.

Implementation of the 2015 European Society of Cardiology guidelines for the management of infective endocarditis in the Netherlands

Because the occurrence of infective endocarditis (IE) continues to be associated with high mortality, a working group was created by the Dutch Society of Cardiology to examine how the most recent European Society of Cardiology (ESC) guidelines for IE management could be implemented most effectively in the Netherlands. In order to investigate current Dutch IE practices, the working group conducted a country-wide survey. Based on the results obtained, it was concluded that most ESC recommendations could be endorsed, albeit with some adjustments. For instance, the suggested pre-operative screening and treatment of nasal carriers of Staphylococcus aureus as formulated in the ESC guideline was found to be dissimilar to current Dutch practice, and was therefore made less restrictive. The recently adapted ESC diagnostic criteria for IE were endorsed, while the practical employment of the relevant diagnostic techniques was simplified in an adapted flowchart. In addition, the presence of a multidisciplinary, so-called ‘endocarditis team’ in tertiary centres was proposed as a quality indicator. An adapted flowchart specifically tailored to Dutch practice for microbiological diagnostic purposes was constructed. Lastly, the working group recommended the Stichting Werkgroep Antibioticabeleid (SWAB; Dutch Working Party on Antibiotic Policy) guidelines for IE treatment instead of the antibiotic regimens proposed by the ESC.

Detection of Native and Prosthetic Valve Endocarditis: Incremental Attributes of Functional FDG PET/CT over Morphologic Imaging

PURPOSE OF REVIEW

The clinical and incremental value of functional imaging with ¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG PET/CT) for the diagnosis and management of patients with suspected native and prosthetic valve infective endocarditis (IE).

RECENT FINDINGS

The diagnosis of IE is challenging because of the highly variable clinical presentations, especially in the case of prosthetic valve endocarditis (PVE). FDG PET/CT has been shown to play an important role for the diagnosis of PVE as a major Duke criterion. Whether FDG PET/CT could play a similar role in patients with suspected native valve endocarditis (NVE) is less well established. It is increasingly recognized that IE is a multisystem disorder, and identification of extra-cardiac manifestations on whole-body FDG PET/CT impacts management and prognosis of patients with IE. Finally, FDG PET/CT provides incremental prognostic value over other clinical and para-clinical parameters, enabling prediction of in-hospital mortality, IE recurrence, hospitalization, and new onset heart failure and embolic events. FDG PET/CT plays a key role in the investigation of patients with suspected IE, enabling detection of valvular infection and extra-cardiac manifestations of the infection which has important prognostic implications.

Three dimensional transesophageal echocardiography: a missing link in infective endocarditis imaging?

The role of two dimensional (2D) echocardiography (ECHO) for the diagnosis and clinical decision making in infective endocarditis (IE) has been extensively studied and described in the medical literature. Some reports have demonstrated the incremental value of three dimensional (3D) transesophageal (TE) ECHO in the setting of IE. However, a systematic review focusing on the role of 3D imaging is lacking. In this manuscript, we examine the role of 3D TE ECHO in the diagnosis of IE. IE is a challenging disease in which 2D transthoracic (TT) and TE ECHO have complementary roles and are unequivocally the mainstay of diagnostic imaging. Still, 2D imaging has important limitations. Technological advances in 3D imaging allow for the reconstruction of real-time anatomical images of cardiac structure and function. 3D imaging has emerged as a diagnostic technique that overcame some of the limitations of 2D ECHO. Currently, both transthoracic and transesophageal echocardiography transducers are able to generate 3D images. However, 3D TE ECHO provides images of a higher quality in comparison to 3D TT ECHO, and is the best echocardiographic modality able to allow for a detailed anatomical imaging. 3D TE ECHO may represent the key adjunctive echocardiographic technique being able to positively impact on IE-related surgical planning and intervention and to facilitate the interaction between the surgeon and the imaging specialist. Importantly, 3D TE ECHO is not the recommended initial modality of choice for the diagnosis of IE; however, in highly specialized centers, it has become an important complementary technique when advanced surgical planning is required. Furthermore, anatomical imaging has become the link between the different techniques that play a role in IE imaging. In fact, both computed tomography and magnetic resonance allow three dimensional reconstruction. An important future goal should allow for the fusion among various imaging modalities. Our review highlights the role of 3D TE ECHO in IE imaging and emphasize where it offers incremental value.

Value of Computed Tomography Radiomic Features for Differentiation of Periprosthetic Mass in Patients With Suspected Prosthetic Valve Obstruction

Background:

We aimed to determine whether quantitative computed tomography radiomic features can aid in differentiating between the causes of prosthetic valve obstruction (PVO) in patients who had undergone prosthetic valve replacement.

Methods:

This retrospective study included 39 periprosthetic masses in 34 patients who underwent cardiac computed tomography scan from January 2014 to August 2017 and were clinically suspected as PVO. The cause of PVO was assessed by redo-surgery and follow-up imaging as standard reference, and classified as pannus, thrombus, or vegetation. Visual analysis was performed to assess the possible cause of PVO on axial and valve-dedicated views. Computed tomography radiomic analysis of periprosthetic masses was performed and radiomic features were extracted. The advantage of radiomic score compared with visual analysis for differentiation of pannus from other abnormalities was assessed.

Results:

Of 39 masses, there were 20 cases of pannus, 11 of thrombus, and 8 of vegetation on final diagnosis. The radiomic score was significantly higher in the pannus group compared with nonpannus group (mean, −0.156±0.422 versus −0.883±0.474; P <0.001). The area under the curve of radiomic score for diagnosis of pannus was 0.876 (95% CI, 0.731–0.960). Combination of radiomic score and visual analysis showed a better performance for the differentiation of pannus than visual analysis alone.

Conclusions:

Compared with visual analysis, computed tomography radiomic features may have added value for differentiating pannus from thrombus or vegetation in patients with suspected PVO.

Meta-analysis of 18F-FDG PET/CT in the diagnosis of infective endocarditis

BACKGROUND

The current diagnosis of infective endocarditis (IE) is based on the modified Duke criteria, which has approximately 80% sensitivity for the diagnosis of native valve endocarditis (NVE), with lower sensitivity for the diagnosis of prosthetic valve endocarditis (PVE) and culture-negative endocarditis. There is preliminary evidence that 18F-FDG PET/CT is an adjunctive diagnostic test with high accuracy reported in small studies to date. We therefore performed a meta-analysis of studies evaluating the use of PET/CT in the diagnosis of IE to establish a more precise estimate of accuracy.

METHODS

PubMed, Embase, Cochrane library, CINAHL, Web of Knowledge, and www.clinicaltrials.gov were searched from January 1990 to April 2017 for studies evaluating the accuracy of PET/CT for the evaluation of possible IE.

RESULTS

We identified 13 studies involving 537 patients that were included in the meta-analysis. The pooled sensitivity of PET/CT for diagnosis of IE was 76.8% (95% CI 71.8-81.4%; Q = 39.9, P < 0.01; I2 = 69.9%) and the pooled specificity was 77.9% (95% CI 71.9-83.2%; Q = 44.42, P < 0.01; I2 = 73.0%). Diagnostic accuracy was improved for PVE with sensitivity of 80.5% (95% CI 74.1-86.0%; Q = 25.5, P < 0.01; I2 = 72.5%) and specificity of 73.1% (95% CI 63.8-81.2%; Q = 32.1, P < 0.01; I2 = 78.2%). Additional extracardiac foci of infection were found on 17% of patients on whole body PET/CT.

CONCLUSION

PET/CT is a useful adjunctive diagnostic tool in the evaluation of diagnostically challenging cases of IE, particularly in prosthetic valve endocarditis. It also has the potential to detect clinically relevant extracardiac foci of infection, malignancy, and other sources of inflammation leading to more appropriate treatment regimens and surgical intervention.

The pivotal role of cardiac computed tomography angiogram and 18F-fluorodeoxyglucose positron emission tomography-computed tomography in the diagnosis of right sided endocarditis: a case report

Background

Infective endocarditis (IE) poses many clinical and diagnostic challenges. Echocardiography is regarded as the imaging modality of choice for the diagnosis of IE, and plays a key role in both the diagnosis and management of endocarditis. We report on a case in which one could have overlooked an endocarditis of a pulmonary homograft if one had relied on echocardiography alone.

Case summary

A 38-year-old man presented with intermittent fever and fatigue for 1 month. He had undergone a Ross procedure for a bicuspid aortic valve stenosis at the age of 17 years. At the age of 36 years a valve-sparing aortic root replacement was performed because of aortic root dilatation. Besides a systolic murmur 3/6 noted at the left sternal border, physical examination was normal. Multiple blood cultures grew Streptococcus mitis. Both transthoracic and transoesophageal echocardiogram could not detect any signs of endocarditis. As endocarditis can be overlooked due to reverberations and acoustic shadowing, we performed ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG-PET/CT) and cardiac computed tomography angiogram (cardiac CTA). Both imaging modalities showed large vegetations attached to the pulmonary homograft.

Discussion

Endocarditis poses diagnostic challenges. While echocardiography is the cornerstone of imaging, one may overlook a pulmonary homograft endocarditis due to reverberations and acoustic shadowing. Therefore, if clinical suspicion of endocarditis is strong, one should consider additional imaging by means of cardiac CTA and/or ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography imaging to assess valves in pulmonary position, especially in those whom have had prior surgical intervention at this location.

18F-FDG PET/CT in the Diagnosis and Management of Continuous Flow Left Ventricular Assist Device Infections: A Case Series and Review of the Literature

Supplemental Digital Content is available in the text.

Implantable continuous flow left ventricular assist devices (LVADs) are increasingly used in end-stage heart failure treatment as a bridge-to-transplant and destination therapy (DT). However, LVADs still have major drawbacks, such as infections that can cause morbidity and mortality. Unfortunately, appropriate diagnosis of LVAD-related and LVAD-specific infections can be very cumbersome. The differentiation between deep and superficial infections is crucial in clinical decision-making. Despite a decade of experience in using fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) to diagnose various infections, its use in LVAD patients remains scarce. In this case series, we review the current evidence in literature and describe our single center experience using ¹⁸F-FDG PET/CT for the diagnosis and management of LVAD infections.

Diagnostic dilemma in prosthetic valve endocarditis: Computed tomography to the rescue

A 58-year-old man with multiple myeloma, prior bioprosthetic valve, spinal hardware and multiple episodes of Corynebacterium amycolatum bacteremia was found to have a well-seated valve without vegetations, paravalvular leak, abscess or degeneration over a period of 6 months on five separate transesophageal echocardiographic studies. Computed tomography angiography was performed which revealed vegetation at the level of the left ventricular outflow tract. Reoperative sternotomy and interrogation of the valve confirmed a 1.5-cm vegetation with the same bacterium. The patient underwent a redo aortic valve replacement and recovered without any complications. He has been asymptomatic and culture negative on surveillance.

CT angiography for depiction of complications after the Bentall procedure

Following a Bentall procedure, which comprises a composite replacement of both the aortic valve and the ascending aorta, the imaging modality of choice to depict known or suspected complications is CT angiography. An update and extension of the literature regarding complications after the Bentall procedure is provided. The wider availability of ECG-gating has allowed for a clearer depiction of the aortic valve and ascending aorta. This resulted not only in the identification of previously undetectable complications, but also in a more precise assessment of the pathophysiology and morphology of known ones, reducing the need for additional imaging modalities. Moreover, the possibility to combine positron emission tomography images with CT angiography offers new insights in case of suspected infection. Due to the complexity of the operation itself and concomitant or subsequent additional procedures, as well as the wide spectrum of underlying pathology, new scenarios with multiple complications can be expected.

Advanced imaging improves the diagnosis of infective endocarditis

Infective endocarditis is a heterogeneous condition whose incidence is rising. Despite advances in surgery and diagnostic methods, one-year mortality has not changed and it remains at 30%. Patients with prosthetic valve and intra-cardiac device–related endocarditis are being seen more frequently and this condition is difficult to diagnose with conventional microbiological and imaging techniques. The modified Duke criteria lack sensitivity in this group and should be supplemented with newer imaging techniques, including 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) and single-photon emission computed tomography (SPECT). In this article, we discuss these techniques and their role in the diagnosis of infective endocarditis.

Echocardiography in Infective Endocarditis: State of the Art

PURPOSE OF REVIEW

In this review, we examine the central role of echocardiography in the diagnosis, prognosis, and management of infective endocarditis (IE).

RECENT FINDINGS

2D transthoracic echocardiography (TTE) and transesophageal echocardiography TEE have complementary roles and are unequivocally the mainstay of diagnostic imaging in IE. The advent of 3D and multiplanar imaging have greatly enhanced the ability of the imager to evaluate cardiac structure and function. Technologic advances in 3D imaging allow for the reconstruction of realistic anatomic images that in turn have positively impacted IE-related surgical planning and intervention. CT and metabolic imaging appear to be emerging as promising ancillary diagnostic tools that could be deployed in select scenarios to circumvent some of the limitations of echocardiography. Our review summarizes the indispensable and central role of various echocardiographic modalities in the management of infective endocarditis. The complementary role of 2D TTE and TEE are discussed and areas where 3D TEE offers incremental value highlighted. An algorithm summarizing a contemporary approach to the workup of endocarditis is provided and major societal guidelines for timing of surgery are reviewed.

Colon cancer and enterococcus bacteremia co-affection: A dangerous alliance

Adenocarcinoma of the colorectal region is one of the leading causes of cancer-related mortality in the USA and hence an important public health concern. Enterococci are emerging as an important cause of infection in the elderly. While translocation of enteric bacteria into the bloodstream is a known phenomenon in patients with infectious, inflammatory or infiltrative conditions of the bowel, a causative link between Enterococcus bacteremia and colorectal cancer has not been established in medical literature. We report the case of a patient presenting with E. faecalis bacteremia who was also diagnosed with infiltrating adenocarcinoma of the rectum. We discuss a possible relationship between these two conditions.

Complementary role of cardiac CT in the assessment of aortic valve replacement dysfunction

Aortic valve replacement is the second most common cardiothoracic procedure in the UK. With an ageing population, there are an increasing number of patients with prosthetic valves that require follow-up. Imaging of prosthetic valves is challenging with conventional echocardiographic techniques making early detection of valve dysfunction or complications difficult. CT has recently emerged as a complementary approach offering excellent spatial resolution and the ability to identify a range of aortic valve replacement complications including structural valve dysfunction, thrombus development, pannus formation and prosthetic valve infective endocarditis. This review discusses each and how CT might be incorporated into a multimodal cardiovascular imaging pathway for the assessment of aortic valve replacements and in guiding clinical management.