Right Sided Endocarditis

Right-sided IE is a particularly common problem in injection drug users. The majority of vegetations in right-sided endocarditis are found on the tricuspid valve, usually on the atrial side. Occasionally vegetations can encase the entire leaflet or be on the ventricular side of the tricuspid valve. Right-sided vegetations tend to be large (10 to 20 mm or more) regardless of the causative organism. Tricuspid valve regurgitation can be present and can range in severity from mild to severe [44-46].

Transthoracic Echo

Vegetations in right-sided IE in injection drug users were initially described on M-mode and 2 D echo in 1980 [44]. Most cases of right-sided endocarditis are readily diagnosed by TTE, because the vegetations are usually large (Figure 7.13). Rarely right-sided vegetations can involve the Eustachian valve. In a large series of endocarditis, five cases of Eustachian valve endocarditis were identified, representing 3.3% of all cases of right-sided endocarditis [47]. In four of the five cases, there were also vegetations on the tricuspid valve. In only one case IE was isolated to the Eustachian valve. The diagnosis was readily made by TTE. The key to distinguishing vegetation from the normal Eustachian valve was abnormal thickness (> 5) mm and chaotic, independent motion unrelated to the cardiac cycle [47].

Right-sided endocarditis can involve the pul-monic valve. The majority of pulmonic valve endocarditis occurs in patients with prior intervention for congenital heart disease. In the absence of prior cardiac intervention, the usual setting of pulmonic valve endocarditis is either injection drug use or indwelling central lines [48]. The majority of cases are readily diagnosed

Figure 7.13. Multiple large vegetations involving the tricuspid valve on transtho-racic echocardiography.

Figure 7.13. Multiple large vegetations involving the tricuspid valve on transtho-racic echocardiography.

by TTE, with a sensitivity for detecting pulmonic vegetations of 91% [48]. In addition to the standard parasternal short axis view, a subcostal view can be useful.

Transesophageal Echo

Transthoracic echo is usually adequate to diagnose right-sided IE and assess the severity of tricuspid valve regurgitation. Although TEE can provide better delineation of the anatomic relationship between vegetation and valve leaflets, the information rarely alters the diagnosis or management [46]. Nevertheless, TEE can be useful in selected patients with suspected right-sided IE as defined in Table 7.12 [49].

Summary

1. Right-sided endocarditis is accurately diagnosed using TTE.

2. Vegetations in right-sided endocarditis are frequently large (5-20 mm) regardless of causative organism.

3. TEE is reserved for specific situations in suspected right-sided IE.

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