Echocardiography in infective endocarditis: reassessment of prognostic implications of vegetation size determined by the transthoracic and the transesophageal approach

Spontaneous drainage of paravalvular abscess diagnosed by transesophageal echocardiography

Paravalvular abscesses, which occur in up to 30% of cases of native valve endocarditis, are being detected with increasing frequency with the use of transesophageal echocardiography. Abscesses of the mitral aortic intervalvular fibrosa have been described but only in association with native or prosthetic aortic valve endocarditis. We describe a patient with native mitral valve endocarditis complicated by an abscess in the fibrosa. A 51-year-old diabetic man presented with Staphylococcus aureus mitral valve endocarditis. A transesophageal echocardiographic study done 8 days after admission revealed two large masses at the base of the anterior mitral leaflet with extension into the fibrosa consistent with a paravalvular abscess that was not detected by precordial echocardiography. A repeat transesophageal echocardiographic study done 20 days after admission showed spontaneous drainage of the abscess and a subsequent fistula between the left atrium and left ventricle. This case highlights the important role that transesophageal echocardiography has in suspected and known cases of endocarditis. Its major advantage of delineating posterior cardiac structures allowed accurate diagnosis and serial evaluation of this previously unreported complication of endocarditis.

Late recurrent Candida endocarditis

Late recurrent Candida endocarditis (LRCE) developed on a prosthetic mitral valve 22 months after treatment for primary native mitral valve endocarditis. The LRCE was difficult to diagnose; results of two dimensional echocardiography and repeated blood cultures were negative. Only transesophageal echocardiography revealed a vegetation and only lysis centrifugation blood cultures demonstrated candidemia. Postmortem examination revealed a large Candida vegetation on the prosthetic valve and Candida in the mitral valve ring. This case and a review of the literature indicate that Candida endocarditis treated with amphotericin B and prosthetic valve replacement may recur months after treatment, and that LRCE, which is difficult to diagnose and treat, may be best prevented by lifelong antifungal suppressive therapy.

Improvement in the diagnosis of abscesses associated with endocarditis by transesophageal echocardiography

BACKGROUND

Echocardiography is recognized as the method of choice for the noninvasive detection of valvular vegetations in patients with infective endocarditis, with transesophageal echocardiography being more accurate than transthoracic echocardiography. The diagnosis of associated abscesses by transthoracic echocardiography is difficult or even impossible in many cases, however, and it is not known whether transesophageal echocardiography is any better.

METHODS

To determine the value of transesophageal echocardiography in the detection of abscesses associated with endocarditis, we studied prospectively by two-dimensional transthoracic and transesophageal echocardiography 118 consecutive patients with infective endocarditis of 137 native or prosthetic valves that was documented during surgery or at autopsy.

RESULTS

During surgery or at autopsy, 44 patients (37.3 percent) had a total of 46 definite regions of abscess. Abscesses were more frequent in aortic-valve endocarditis than in infections of other valves, and the infecting organism was more often staphylococcus (52.3 percent of cases) in patients with abscesses than in those without abscesses (16.2 percent). The hospital mortality rate was 22.7 percent in patients with abscesses, as compared with 13.5 percent in patients without abscesses. Whereas transthoracic echocardiography identified only 13 of the 46 areas of abscess, the transesophageal approach allowed the detection of 40 regions (P less than 0.001). Sensitivity and specificity for the detection of abscesses associated with endocarditis were 28.3 and 98.6 percent, respectively, for transthoracic echocardiography and 87.0 and 94.6 percent for transesophageal echocardiography; positive and negative predictive values were 92.9 and 68.9 percent, respectively, for the transthoracic approach and 90.9 and 92.1 percent for the transesophageal approach. Variation between observers was 3.4 percent for transthoracic and 4.2 percent for transesophageal echocardiography.

CONCLUSIONS

The data indicate that transesophageal echocardiography leads to a significant improvement in the diagnosis of abscesses associated with endocarditis. The technique facilitates the identification of patients with endocarditis who have an increased risk of death and permits earlier treatment.

Diagnosis of noninfective cardiac mass lesions by two-dimensional echocardiography. Comparison of the transthoracic and transesophageal approaches

This study was conducted in 46 patients with cardiac thrombi, 15 patients with atrial myxomas, and 32 patients with other cardiac or paracardiac tumors. Diagnoses were subsequently proven by surgery, autopsy, computed tomography, magnetic resonance imaging, or angiography in all patients. All patients underwent precordial and transesophageal two-dimensional echocardiography to assess the various mass detection rates. Atrial myxomas and predominantly left-sided cardiac tumors were identified by both echocardiographic techniques with comparable detection rates. Left ventricular apical thrombi were detected more frequently by precordial echocardiography. In contrast, transesophageal echocardiography was superior in visualizing left atrial appendage thrombi, small and flat thrombi in the left atrial cavity, thrombi and tumors in the superior vena cava, and masses attached to the right heart and the descending thoracic aorta. These data indicate that transesophageal echocardiography leads to a clinically relevant improvement of the diagnostic potential in patients in whom cardiac masses are suspected or have to be excluded in order to ensure the safety of clinical procedures.

Biplanar transesophageal echocardiography: anatomic correlations, image orientation, and clinical applications

Clinical transesophageal echocardiography is a rapidly expanding diagnostic procedure. Conventional transesophageal endoscopes allow imaging from a single array mounted in the horizontal plane. This article introduces the clinical application of biplanar imaging, which incorporates a second orthogonal longitudinal plane. Our clinical experience with 291 patients who underwent biplanar transesophageal echocardiography is presented. The examination, technique, and resultant anatomic correlations unique to this new examination are discussed and illustrated. The anatomy is displayed in a familiar format comparable to the precordial examination. Biplanar imaging adds substantially to the comprehensive anatomic delineation of certain cardiac structures.

Infective endocarditis, 1983-1988: echocardiographic findings and factors influencing morbidity and mortality

The echocardiograms and clinical records of 70 patients with infective endocarditis seen between 1983 and 1988 were examined to evaluate the role of two-dimensional and Doppler echocardiography in the diagnosis of infective endocarditis and identify risk factors for morbidity and mortality. A blinded observer reviewed the echocardiograms for the presence and size of vegetations and the severity of the valvular regurgitation. Vegetations were identified in 54 (78%) of 69 technically satisfactory echocardiograms. In 38 patients whose heart was examined at surgery or autopsy, all vegetations diagnosed by echocardiography were confirmed, but six additional vegetations were found. Abnormal (greater than or equal to 2+) valvular regurgitation was present in 88% of patients. No patient with less than or equal to 1+ regurgitation (n = 8) died or required valve surgery for heart failure, but three of the eight patients did undergo surgery for mycotic aneurysm, recurrent embolism or paravalvular abscess. In patients without embolism before echocardiography, there was a trend toward a greater incidence of subsequent embolism in those with vegetations greater than 10 mm in size (26% [8 of 31] compared with 11% [2 of 18] with vegetations less than or equal to 10 mm) (p = 0.19). By multivariate analysis, risk factors for in-hospital death (n = 7) were an infected prosthetic valve (p less than 0.007), systemic embolism (p less than 0.02) and infection with Staphylococcus aureus (p = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of electrical stimulus parameters on the development and propagation of action potentials in short excitable fibres

Intracellular action potentials (IAPs) produced by short fibres in response to their electrical stimulation were analysed. IAPs were calculated on the basis of the Hodgkin-Huxley (1952) model by the method described by Joyner et al. (1978). Principal differences were found in processes of activation of short (semilength L less than 5 lambda) and long fibres under near-threshold stimulation. The shorter the fibre, the lower was the threshold value (Ithr). Dependence of the latency on the stimulus strength (Ist) was substantially non-linear and was affected by the fibre length. Both fibre length and stimulus strength influenced the IAP amplitude, the instantaneous propagation velocity (IPV) and the site of the first origin of the IAP (and, consequently, excitability of the short fibre membrane). With L less than or equal to 2 lambda and Ithr less than or equal to Ist less than or equal to 1.1Ithr, IPV could reach either very high values (so that all the fibre membrane fired practically simultaneously) or even negative values. The latter corresponded to the first origin of the propagated IAP, not at the site of stimulation but at the fibre termination or at a midpoint. The characters of all the above dependencies were unchanged irrespective of the manner of approaching threshold (variation of stimulus duration or its strength). Reasons for differences in processes of activation of short and long fibres are discussed in terms of electrical load and latency. Applications of the results to explain an increased jitter, velocity recovery function and velocity-diameter relationship are also discussed.