Staphylococcus aureus bacteraemia: evaluation of the role of transoesophageal echocardiography in identifying clinically unsuspected endocarditis.

Staphylococcus aureus bacteraemia (SAB) is an important cause of community and nosocomial sepsis, with a significant mortality rate. Infective endocarditis (IE) is a serious complication, occurring in up to 25 % of cases. Transoesophageal echocardiography (TOE) significantly improves the sensitivity of diagnosis. We compared the sensitivity and specificity of clinical evaluation alone in diagnosing IE. We evaluated all adult patients with SAB at our centre from 1998 to 2006 in order to determine what proportion of clinically unsuspected cases were diagnosed with IE on TOE. IE was defined according to modified Duke criteria. The median age of the patients was 68 years, 77 % were male and the majority of cases did not have a known pre-existing condition. Twenty-one percent were methicillin-resistant Staphylococcus aureus (MRSA). Intravascular device was the most common cause of bacteraemia. TOE was performed in 144 (100 %) of the cases. IE was suspected clinically in 15 % of cases, and the overall prevalence of possible or definite IE on TOE-inclusive Duke criteria was 29 % (n = 41). Following TOE, 22 (15 %) cases were reclassified as either possible or definite endocarditis. TOE detected a vegetation in 37 (90 %) of the 41 cases of IE. Nineteen (46 %) were not suspected clinically by Duke criteria. Sensitivity improved in the presence of pre-existing valve lesion or community acquisition. The overall in-hospital mortality was 10 %. There is a high incidence of endocarditis in SAB and a large percentage of cases are not evident on clinical grounds. TOE evaluation is indicated for all medically suitable adult patients with SAB in order to improve the detection of endocarditis.

Clinical significance and origin of artifacts in transesophageal echocardiography of the thoracic aorta.

OBJECTIVES: The aim of this study was to identify the mechanism and features of artifacts encountered during transesophageal echocardiography of the aorta. BACKGROUND: Artifacts are an important potential limitation of transesophageal echocardiography of the aorta. METHODS: The mechanism of the artifacts was examined by in vitro modeling. The frequency and clinical correlates of artifacts were examined by retrospective review of transesophageal echocardiograms in 36 patients with aortic pathologic lesions. RESULTS: Two classes of artifact were seen: linear artifacts in the ascending aorta, which may mimic intimal flaps, and mirror image artifacts in the transverse and descending thoracic aorta. Linear artifacts in the ascending aorta, seen in 44% of patients, were shown in vitro to be multiple path artifacts caused by reflection of ultrasound within the left atrium. Linear artifacts in the ascending aorta were associated with dilatation of the ascending aorta and were more frequent when the aortic diameter exceeded the left atrial diameter (p < 0.001). The mirror image artifacts of the transverse and descending thoracic aorta give the appearance of a double-barrel aorta and were shown in vitro to be caused by the aorta-lung interface, which acts as a total reflector of ultrasound. Mirror image artifacts were seen in > 80% of patients. Artifacts were equally frequent with the sagittal and transverse imaging planes when biplane transesophageal echocardiography was used. CONCLUSIONS: Artifacts occur frequently during transesophageal echocardiography of the aorta. An understanding of why they occur and the features that distinguish them from true abnormalities should enhance the diagnostic accuracy of transesophageal echocardiography for aortic disease.

Cardiovascular ultrasound: expanding frontiers in vascular disease.

Advances in cardiovascular ultrasound have included development of instrumentation providing outstanding images, as well as color spectral Doppler hemodynamic information. The increasing utilization of cardiovascular ultrasound has led to its increasing diagnostic application and accuracy in the evaluation of the patient with known or suspected cerebrovascular and peripheral vascular disease. The sensitivity of duplex ultrasound to detect carotid disease varies from 87% to 94% with a specificity of 88% to 93%. The accuracy of duplex examination for detection of peripheral venous disease, when compared to contrast venography, is high. A sensitivity of nearly 93% with a specificity of 98% has been noted. Cardiovascular ultrasound is a noninvasive technology with no known biological hazard that can be applied to the broad spectrum of patients including those who are critically ill. It is a relatively low-cost procedure when compared to other diagnostic procedures and can be performed on a serial basis. Since it provides anatomical and functional hemodynamic information, it is rapidly becoming the procedure of choice not only for diagnosis, but also for management.

Diagnosis of aortic transection by transesophageal echocardiography.

Transesophageal echocardiography (TEE) offers spectacularly detailed images of thoracic aortic anatomy and blood flow; however, its utility for diagnosis of aortic trauma is unknown. Our case underscores the ability of TEE to diagnose aortic transection. The speed, mobility, and accuracy of TEE makes it an attractive means of diagnosing aortic trauma in the critically ill.