Papillary muscle rupture caused by bacterial endocarditis: role of transesophageal echocardiography

[A myocardial infarction complicated with mitral anterior papillary muscle rupture during long-term corticotherapy]

The authors report anterolateral papillary muscle rupture, occurring in a 67-year-old patient admitted for acute coronary syndrome. Mitral regurgitation, a rare but dramatic complication of myocardial infarction, is most often a consequence of posterior papillary muscle rupture. The 'protection' of the anterior papillary muscle is associated with vascularization via a dual coronary artery supply. Possible myocardial weakening associated with long-term corticotherapy is otherwise discussed in this observation.

[Staphylococcus aureus infections: new challenges from an old pathogen]

Staphylococcus aureus is a versatile organism with several virulent characteristics and resistance mechanisms at its disposal. It is also a significant cause of a wide range of infectious diseases in humans. S. aureus often causes life-threatening deep seated infections like bacteremia, endocarditis and pneumonia. While traditionally confined mostly to the hospital setting, methicillin-resistant S. aureus (MRSA) is now rapidly becoming rampant in the community. Community-acquired MRSA is particularly significant because of its potential for unchecked spread within households and its propensity for causing serious skin and pulmonary infections. Because of the unfavorable outcome of many MRSA infections with the standard glycopeptide therapy, new antimicrobial agents belonging to various classes have been introduced and have been evaluated in clinical trials for their efficacy in treating resistant staphylococcal infections. A number of preventive strategies have also been suggested to contain the spread of such infections. In this review, we address the recent changes in the epidemiology of S. aureus and their impact on the clinical manifestations and management of serious infections. We also discuss new treatment modalities for MRSA infections and emphasize the importance of preventive approaches.

Staphylococcus aureus bacteremia and endocarditis

Staphylococcus aureus is a leading cause of bacteremia and endocarditis. Over the past several years, the frequency of S aureus bacteremia (SAB) has increased dramatically. This increasing frequency, coupled with increasing rates of antibiotic resistance, has renewed interest in this serious, common infection. S aureus is a unique pathogen because of its virulent properties, its protean manifestations, and its ability to cause endocarditis on architecturally normal cardiac valves. Although the possibility of underlying endocarditis arises in virtually every patient with SAB, only a minority of bacteremic patients will actually have cardiac involvement. Distinguishing patients with S aureus infective endocarditis (IE) from those with uncomplicated SAB is essential, but often difficult. In this review, the authors summarize recent changes in the epidemiology of SAB and IE, discuss the challenges in distinguishing SAB from IE, and discuss current trends in the management of patients with SAB and IE.

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.

[Mitral regurgitation in infective endocarditis]

Endocarditis affecting the mitral valve is frequent and is associated with specific features. Mitral prolapse is the most frequent underlying disease and the mechanism of mitral regurgitation secondary to infective endocarditis is frequently complex and multiple. Echocardiography plays a key-role in both the diagnosis, the prognostic assessment and the choice of the best therapeutic option in patients with mitral valve endocarditis. Surgery is frequently necessary, and must be performed early in the course of the disease. Mitral valve repair is the best therapeutic option, when technically possible.

Obstructive intramural coronary amyloidosis and papillary muscle rupture

Mitral papillary muscle rupture is usually caused by ischaemia as a complication of myocardial infarction. In a 76 year old patient with no significant disease or major cardiovascular risk factors, papillary muscle rupture was caused by obstructive intramural coronary amyloidosis, an unusual cause.

Staphylococcus aureus bacteremia and endocarditis

Staphylococcus aureus is a leading cause of bacteremia and endocarditis. Over the past several years, the frequency of S. aureus bacteremia (SAB) has increased dramatically. This increasing frequency, coupled with increasing rates of antibiotic resistance, has renewed interest in this serious, common infection. S. aureus is a unique pathogen because of its virulent properties, its protean manifestations, and its ability to cause endocarditis on architecturally normal cardiac valves. Although the possibility of underlying endocarditis arises in virtually every patient with SAB, only a minority of bacteremic patients will actually have cardiac involvement. Distinguishing patients with S. aureus infective endocarditis (IE) from those with uncomplicated SAB is essential, but often difficult. In this review, the authors summarize recent changes in the epidemiology of SAB and IE, discuss the challenges in distinguishing SAB from IE, and discuss current trends in the management of patients with SAB and IE.

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.

Echocardiography for the Diagnosis of Staphylococcus aureus Infective Endocarditis

Staphylococcus aureus bacteremia (SAB) is a serious and growing problem. A longstanding controversy in infectious diseases has centered around the duration of therapy for patients with SAB. Fortunately, the refinement of echocardiography and the creation of new diagnostic criteria have aided in the diagnosis of infective endocarditis in patients with SAB. These advancements have resulted in the development of an algorithm that combines clinical, microbiologic, and echocardiographic findings to stratify patients with SAB into different treatment regimens.

Assessment of endocarditis and associated complications with transesophageal echocardiography

TEE offers many benefits in the evaluation of patients with IE. It provides increased sensitivity as compared to TTE in the detection of this disease, and is better able to identify and delineate many of the associated complications and hemodynamic aberrancies. TEE also has helped expand our knowledge of the pathophysiology and natural history of IE. Continued advances in the technology of TEE instrumentation undoubtedly will lead to further improvements in our ability to assess and to treat patients stricken with this serious infection. Nevertheless, IE continues to exact a significant toll on its victims, and our efforts to diagnose, to treat, and to prevent it must not weaken.

Primary left ventricular mural endocarditis diagnosed by transesophageal echocardiography

Primary left ventricular mural abscess was detected by transesophageal echocardiography and was confirmed at necropsy in a 44-year-old woman with Staphylococcus aureus bacteremia and cerebrovascular embolism. In two occasions, transthoracic echocardiography failed to show the mural abscess in this patient. Because of the aggressive nature of primary mural endocarditis, early use of transesophageal echocardiography is recommended in patients with Staphylococcal bacteremia and suspected endocarditis even in the absence of valvular abnormalities detectable by the transthoracic approach.