Aortic root abscess complicating bacterial endocarditis. Demonstration by computed tomography

Infective Endocarditis

Infective endocarditis (IE) is a noncontagious infection of the endocardium and heart valves. The epidemiology of IE has shifted recently with an increase in health care-associated IE. Infective endocarditis requiring intensive care unit stay is increasing, and nosocomial IE is frequently responsible. Diagnosis of IE requires multiple clinical data points encompassing history and physical examination, microbiology, and cardiac imaging as no one test is sufficiently sensitive or specific. The modified Duke criteria algorithm is the standard of care in the clinical diagnosis of IE. Complications from IE are common, particularly so in the critical care setting, and include congestive heart failure, embolism, septic shock, invasive infection, prosthetic valve dehiscence, heart block, and mycotic aneurysm. A multidisciplinary care team of infectious disease, cardiology, and cardiac surgery physicians is recommended to reduce complications. Intravenous antibiotics are first-line therapy with cardiac surgery being reserved for certain complications of IE and/or for clinical situations in which there is a high risk of complications. Timing of surgery for IE remains controversial and depends on a variety of clinical factors.

Myocardial abscess and fatal cardiac arrhythmia in a hemodialysis patient with an arterio-venous fistula infection

Myocardial abscess formation is a life-threatening complication that is frequently but not exclusively associated with infective endocarditis. To our knowledge there are only two case reports of myocardial abscess formation in hemodialysis patients. Only one of these reports describes a myocardial abscess of bacterial etiology secondary to an infected intravascular hemodialysis catheter. Furthermore, there are no reports of bacterial myocardial abscess occurring in a hemodialysis patient with an infected arteriovenous fistula. Myocardial abscess can manifest in a variety of clinical scenarios ranging from an asymptomatic state to a catastrophic myocardial wall rupture. In the case described, the myocardial abscess lead to a rapidly progressive course consisting of recurrent cardiac arrhythmias that were ultimately fatal. Our case involved the formation of a myocardial abscess in the presence of a methicillin-resistant Staphylococcus aureus bacteremia without any evidence of infective endocarditis. We report this case to call attention to the possibility of bacterial myocardial abscess occurring with infection of an arteriovenous fistula in a hemodialysis patient, which can manifest as recurrent severe cardiac arrhythmias refractory to medical therapy.

Evaluation of prosthetic valve endocarditis by 64-row multidetector computed tomography

Two patients with prosthetic aortic valves--one bioprosthetic and one mechanical--presented with bacteremia and underwent evaluation for infective prosthetic valve endocarditis. Multidetector computed tomography (MDCT) imaging demonstrated vegetations on both prosthetic valves confirmed by transesophageal echocardiography. Based on the MDCT coronary artery assessment, neither patient underwent pre-operative invasive coronary angiography. Both patients underwent surgical treatment without complication. In conclusion, this report demonstrates that MDCT can, in some cases, accurately image vegetations on prosthetic aortic valves in infective endocarditis.

MDCT Evaluation of Aortic Valvular Disease

OBJECTIVE

This essay depicts recent advances of MDCT in the evaluation of aortic valvular disease.

CONCLUSION

Aortic valvular disease can be assessed with current MDCT technology. The improved imaging characteristics of MDCT have significantly decreased artifacts traditionally seen with prosthetic aortic valves and enabled excellent visualization of valve function. Advances in ECG-gated MDCT technology offer the opportunity to evaluate a variety of aortic valvular abnormalities.

Using 18-fluoro-2-deoxyglucose positron emission tomography in detecting infectious endocarditis/endoarteritis

RATIONALE AND OBJECTIVES

We evaluated the effectiveness of positron emission tomography (PET) with 18-fluoro-2-deoxyglucose (FDG) in the detection of infectious endocarditis/endoarteritis.

MATERIALS AND METHODS

For this study, we recruited 6 patients (4 women, 2 men; age range, 35 - 78 years; mean age, 55.8 +/- 16.8 years) who were clinically diagnosed as having infective endocarditis/endoarteritis by their echocardiographic findings and by Duke criteria.

RESULTS

For all 6 patients, we also found increased FDG uptakes in the corresponding areas detected in echocardiography.

CONCLUSION

FDG-PET appears to be a promising tool in diagnosing infective endocarditis/endoarteritis, and further prospective studies on a large scale to fully exploit the usefulness of FDG-PET for infective endocarditis/endoarteritis are needed.

Imaging techniques for diagnosis of infective endocarditis

Cardiac imaging, specifically echocardiography, has greatly enhanced the ability of clinicians to effectively diagnose and manage IE. Echocardiograms should generally be obtained in all patients suspected of having IE, both to establish the diagnosis and to identify complicated cardiac involvement that may warrant surgical intervention. Transesophageal imaging is more sensitive and specific than the transthoracic approach and currently represents the optimal approach to echocardiographic imaging. Manifestations of endocardial involvement include vegetations, abscesses, aneurysms, fistulae, leaflet perforations, and valvular dehiscence. The roles of other imaging modalities including CT, MRI, and nuclear imaging have yet to be fully established.

Imaging techniques for diagnosis of infective endocarditis

With the ability to structurally characterize cardiac manifestations, echocardiography is used for the diagnosis and management of infective endocarditis. In establishing the diagnosis according to the Duke criteria, the findings of endocardial involvement (vegetation, abscess, prosthetic valve dehiscence) or new valvular regurgitation represent "major" diagnostic criteria. As echocardiography cannot reliably differentiate noninfective from infective lesions, however, proper diagnosis lies in correlating echocardiography with clinical findings. The more invasive transesophageal approach provides substantially greater image resolution; this approach should be considered first in the evaluation of patients with higher prior probabilities of endocarditis and those with potential endocardial complications.

False Aneurysm of the Aortic Root and Right Ventricular Outflow Obstruction: An Unusual Complication of Surgically Treated Infective Endocarditis

Aortic root abscess often complicates the course of aortic valve endocarditis. In severe cases, left ventricular-aortic discontinuity may occur, providing challenging technical problems for the surgeon. Moreover, surgical intervention sometimes takes place in a semi-emergency context, and the patches and prosthesis are sutured into friable tissues and subjected to high systemic pressures. Subsequently, paravalvular leaks and prosthesis dehiscence are not uncommon; postoperative false aneurysm of the aortic root is a much more unusual complication. We report one case of right ventricular outflow obstruction that occurred after surgical treatment of an aortic root abscess. Echocardiographic data were useful, but magnetic resonance imaging provided valuable information about the anatomic extent of the cavity. (ECHOCARDIOGRAPHY, Volume 13, January 1996)

Diagnostic evaluation of myocardial abscesses. A new look at an old problem

A myocardial abscess is a life threatening complication of infective endocarditis that necessitates early diagnosis in order to identify the need for emergent surgical intervention and improved prognosis. This review discusses the relevant historical aspects, clinical features suggestive of the diagnosis, associated conditions and various appropriate imaging modalities--in particular, trans-thoracic and trans-esophageal echocardiography, Indium-111 radionucleide scintigraphy, and computerized tomographic scanning. Specific clinical and echocardiographic criteria for identifying a myocardial abscess are discussed and comparative data presented from published studies in the literature.

Complementary role of MRI in infectious endocarditis

The usefulness of magnetic resonance for imaging of cardiac structures is well established. In this study, we evaluated the role of this technique in the diagnosis of perivalvular extension of infectious endocarditis. Our initial experience and the few case reports in the literature show that magnetic resonance imaging can complement echocardiography in the assessment of periannular extension of infectious endocarditis.

Persistent root abscess after emergency repair with an aortic homograft

A fifty eight year old man with Marfan's syndrome and an aortic composite graft with a Björk-Shiley mechanical prosthesis presented with a large aortic root abscess caused by Staphylococcus aureus endocarditis. Despite extensive surgical debridement and implantation of an aortic homograft as a composite graft, early postoperative transoesophageal echocardiography continued to demonstrate a large aortic root abscess and the patient died in a septic shock.

Predictive risk factors for periannular extension of native valve endocarditis. Clinical and echocardiographic analyses

The study objective is to identify clinical, microbiologic, and/or echocardiographic risk factors present early in the course of native valve endocarditis that predict subsequent development of periannular extension of infection. A multivariate computer-generated analysis of 21 clinical-microbiologic parameters and 11 two-dimensional echocardiographic parameters in patients with native valve endocarditis was designed. These parameters were statistically compared in operated-on patients with native valve endocarditis with and without periannular extension of infection. The study took place in a 600-bed acute-care, nonreferral, municipal hospital primarily servicing an indigent patient population. Seventy-three documented episodes of native valve endocarditis occurred between the years of 1973 and 1987, including 29 operated-on patients with surgically confirmed periannular extension of infection and 44 operated-on patients without periannular extension of infection. Multivariate logistic-regression analyses of multiple clinical, microbiologic, and echocardiographic parameters which are potentially predictive of eventual periannular extension of native valve endocarditis were carried out. The only two independent parameters that significantly predicted periannular infection among patients with native valve endocarditis were (1) aortic valve involvement and (2) abuse of intravenous (IV) drugs (p less than 0.01; p less than 0.01, respectively, multivariate analysis). The relative risk of developing periannular extension of endocarditis among patients with aortic valve involvement and/or IV drug abuse was increased by approximately 2.5-fold compared with patients without these characteristics. Factors not significantly associated with increased risk of periannular extension of native valve endocarditis included the following: prolonged febrile morbidity; Staphylococcus aureus etiology; or two-dimensional echocardiographic demonstration of vegetations, large vegetations (greater than or equal to 1 cm), multiple vegetations, or enlargement of aortic root or annulus. These data suggest that patients with native aortic valve endocarditis, particularly in the setting of IV drug abuse, should be considered for routine, serial noninvasive evaluation for the early detection of periannular extension of their infection.

Demonstration of the ascending aorta in infective endocarditis by intravenous digital subtraction angiography

Four patients with infective endocarditis were examined by digital subtraction angiography immediately before operation. In three a root abscess was suspected and the remaining patient was believed to have a false aneurysm at an infected aortic cannulation site. In all the cases digital subtraction angiography showed the structure in several projections and confirmed the presence of a cavity. Subsequent operation confirmed the site and nature of the lesions.

Mycotic aneurysms of the aortic root. A pathologic study of 20 cases

Twenty specimens of heart with mycotic aneurysms at the aortic root were studied. In ten cases, mycotic aneurysm followed infection of the aortic valve. In one case, it developed following infection of an aortic jet lesion, and in nine patients, the aneurysm was at the seat of a prosthetic aortic valve. In seven of the 11 cases with a natural aortic valve, the valve was either unicuspid or bicuspid. A retrospective evaluation of the data on the clinical records of the 20 patients revealed that infective endocarditis or noncardiac postoperative sepsis was present in 11. The most frequently isolated microorganism was Staphylococcus aureus. Conduction disturbances were found in six patients, all of them with involvement of the atrioventricular node by the aneurysm. Perforation into intracardiac cavities was found in four, two into the right ventricular infundibulum and one each into each atrium. Pericardial tamponade was caused by bleeding from the aneurysm in two cases, and myocardial infarction was a probable consequence of coronary arterial compression by the aneurysm in two cases. Mycotic aneurysms of the aortic root, in spite of their being partially or completely healed of active infection, carry a high risk of the complications enumerated. Among the 20 cases, cultures were positive in 11 and negative in nine. Staphylococcus aureus was cultured from five of the cases.