ClinicalRadiology (1986) 37, 235-238 © 1986 Royal College of Radiologists
0009-9260/86/641235502.00
The Diagnosis of Aortic Root Abscess by Cross-sectional Echocardiography D. M U L C A H Y , L. M. S H A P I R O , C A R O L I N E W E S T G A T E , D. N. ROSS and R. D O N A L D S O N
National Heart Hospital, London
Aortic root abscess is frequently a lethal complication of infective endocarditis. Early diagnosis of this complication is of paramount importance because antibiotic therapy is often ineffective and early surgery is probably the treatment of choice. We have compared the diagnostic accuracy of cross-sectional echocardiography with operative findings in the diagnosis of aortic root abscess. Aortic root abscess was diagnosed in nine of 129 patients with infective endocarditis at the National Heart Hospital between 1983 and 1985. Cross-sectional echocardiography demonstrated the presence and location of the aortic root abscess in eight cases; in the ninth case a small abscess was missed. In two other cases, a large abscess was visualised, but abscesses of between 2 m m and 4 m m were missed; the extent and size of large aortic abscesses tended to be underestimated. Echocardiography should be an integral part of the investigation of patients with aortic valve infective endocarditis.
sence of an abscess was diagnosed when an echo-free space was observed outside the normal contours of the aortic root using multiple cross-sectional views. Aortic root abscesses were classified on the basis of short-axis parasternal views into anterior, posterior, lateral and circumferential. Clinical details and operative findings were extracted from the case notes.
RESULTS Twenty-three patients underwent surgery during the active phase of infective endocarditis: an aortic root abscess was identified in nine; in eight, the aortic root abscess was seen pre-operatively by cross-sectional
Destruction of the valve cusps and aortic root abscess are two of the m a j o r causes of mortality in infective endocarditis of the aortic valve. Prolonged antibiotic therapy is often ineffective and early surgical intervention with valve replacement and excision of all the infected material may effect a cure in a significant proportion of cases. However, the diagnosis of vegetations and aortic root abscess remain a problem, and, because of the risks of cardiac catheterisation in these patients, cross-sectional echocardiography has become the method of choice (Gilbert et al., 1977; Scanlan et al., 1982). We report the findings of a study comparing the diagnostic accuracy of cross-sectional echocardiography with the operative findings in patients with aortic root abscess. The outcome of operative treatment is also discussed.
PATIENTS AND M E T H O D S Routine cross-sectional echocardiography was performed in 4770 patients at the National H e a r t Hospital non-invasive laboratory between 1983 and 1985. During this period infective endocarditis was diagnosed by clinical and bacteriological means in 129 patients. Crosssectional echocardiograms were carried out with Hewlett-Packard phased array equipment (model 77020A) with a 3.5 or 5 m H z transducer. Complete echocardiographic studies using parasternal, subxiphoid, suprasternal and apical views were routinely obtained and recorded on 0.5 in video tape. The preAddress for correspondence: Dr L. M. Shapiro, National Heart Hospital, London WlM 8BA.
Fig. 1 - Cross-sectional echocardiogram through the aortic root in a pahent (B. S.) with a Starr-Edwards (SE) aortic valve replacement. An abscess cavity (ab) may be observed anterior to the aortic root. (Rv=right ventricle, Pa=pulmonary artery, La=left atrium).
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Fig. 2 - Long axis parasternal cross-sectional echocardiogram in patient H.D. A large abscess cavity (a) can be seen posterior to the aortic root (AO).
patient (R.O.), a small abscess was diagnosed at operation; subsequent examination of the cross-sectional echocardiogram revealed a small lateral echo-free space of less than 3 mm in thickness and a flail aortic valve with large vegetations. In two cases (A.H., B.S.), though the larger aortic root abscess was identified in its correct location, one smaller abscess was missed. The size of small abscesses seen at operation was estimated at between 2 mm and 4 mm in diameter. In addition, the extent of a large aortic root abscess in two patients (N.H., H.H.) was underestimated by cross-sectional echocardiography; in both cases the abscess was undermining the mitral valve, in one leading to detachment of the valve and in the other separation of the aorta and left ventricle. The patients with aortic root abscesses included three with infective endocarditis on native aortic valves. The rest had between one and four previous aortic valve replacements (Table 1). The presence of a biological (three cases) or mechanical aortic valve replacement did not interfere with the diagnosis of aortic root abscess (Figs 1, 3 and 4). The surgical outcome of aortic root abscess was that three patients, each of whom had had at least one previous aortic valve replacement, died in the immediate post-operative period and six patients were alive and free from infection up to 18 months later (Table 1). DISCUSSION
echocardiography and confirmed at operation (Figs 1-5). While no false positive diagnoses were made, the presence of false negative diagnoses is unknown as not all patients with infective endocarditis underwent surgery or necropsy. In these eight cases, the location of the aortic root abscess was identified correctly. In one
(a)
(b)
At autopsy, a valve ring abscess may be demonstrated frequently in patients dying of infective endocarditis (Sheldon and Golden, 1951). Aortic root abscess was reported at necropsy in 41% of a group of patients who died from infective endocarditis involving the aortic valve (Arnett and Roberts, 1976). Aortic root abscess is
(c)
Fig. 3 - Cross-sectional views of the aortic root in patient J.L. (a) showing a Starr-Edwards aortic valve replacement. (b) A t the mid-portion of the cage of the aortic valve one can see a small abscess cavity (a) in the posterior region of the aortic root. (c) Higher in the aortic root around the top of the valve cage, a large abscess cavity (a) can be seen extending posteriorly into the area of the right atrium.
DIAGNOSIS OF AORTIC ROOT ABSCESS BY CROSS-SECTIONAL E C H O C A R D I O G R A P H Y
(a)
237
(b)
Fig. 4 - Cross-sectionalechocardiogramin patient M.S. (a) Long axisview,in which an abscesscavity (a) may be seen posterior to the Start-Edwards
(se) aortic valve replacement, Lv=left ventricle). (b) Cross-sectionin which this abscess cavitycan be seen to be lying posterior and lateral to the aortic root.
Fig. 5 - Cross-sectional echocardiogram through the aortic root in patient G.G. This shows that the aortic root is surrounded by an echofree space (a). At surgery this was shown to be an abscess cavity. (Ao = aorta, LA =left atrium).
an ominous complication of infective endocarditis, and the natural history of this disease may be more rapid and lethal in the presence of such an abscess (Utley and Mills, 1972). Thus, the early and accurate detection of this complication is of paramount importance, especially as medical therapy is often unsatisfactory and early surgery may be the treatment of choice (Mardelli et al., 1978; Donaldson and Ross, 1984). All of the patients had complicated infective endocarditis and all but three had previously undergone aortic valve surgery. Despite the severity of the underlying disease, the surgical outcome was favourable with aortic valve or root replacement resulting in correction of haemodynamic disturbance and eradication of infection in the majority. We have shown that cross-sectional echocardiography may reliably diagnose the presence and location of aortic root abscess (Wong et al., 1981; Scanlan et al., 1982). Abscesses less than 2 - 4 mm in size were missed in all but one case. The extent of large aortic root abscesses were underestimated, usually because of the extensive tracking and undermining of other cardiac structures. With the equipment and techniques used, aortic root abscesses were readily diagnosed in the presence of prosthetic aortic valves. Cross-sectional echocardiography diagnosed a root abscess in 7% of patients with infective endocarditis. This diagnosis must be considered in patients with aortic valve endocarditis especially in the presence of severe regurgitation or severe, early symptoms. The demonstration of an echo-free space outside the normal contours of the aortic root should prompt early surgery rather than persisting with often ineffective antibiotic therapy.
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Table 1 - Clinical and eehocardiographic findings in patients with aortic root abscesses in infective endocarditis
Patzent
Age (years), Aortic valve sex replacement
Organism
Cross-sectional Survtval echocardiography
Operative findings
M.S.
63, F
CE (2)
Staphylococcus epidermis
Postero-lateral
+7 weeks
J.L.
33, M
SE (4)
Staphylococcus epidermis
Posterior
18 months
P.B.
51, M
-
Staphylococcus epidermis
Anterior
17 months
H.H.
83, M
Homograft
Unknown
Posterior
+9 weeks
R.O.
14, M
-
Haemophilus influenzae
Lateral*
8 months
G.G.
36, M
Q Fever
Circumferential
1 month
A.H.
56, M
Aortic root replacement (4) SE (2)
Streptococcus viridans
Lateral
B.S.
39, M
SE (2)
Streptococcus viridans
Anterior
3 months
H.D.
9, M
-
Streptococcus viridans
Posterior
3 months
Left ventricle and aorta separated by abscess Abscess burrowing between aorta and right atrium posterior to the aortic root Abscess beneath right coronary cusp Abscess beneath aortic valve detaching anterior leaflet of mitral valve Cavity beneath right coronary sinus Abscess around aorta extending into right atrium Abscess in non-coronary and right coronary sinuses Abscess behind pulmonary artery; small abscess in superior vena cava Abscess posterior to aorta
+5 days
C E - C a r p e n t e r Edwards, SE=Starr Edwards. *Demonstrated rectrospectively. + =died. REFERENCES
Arnett, E. N. & Roberts, W. C. (1976). Valve ring abscess in active infective endocarditis. Ctrculation, 54, 140-145. Donaldson, R. M. & Ross, D. M. (1984). Homograft aortic root replacement for complicated prosthetic valve endocarditls. Circulation. Suppl. 1, 70, 178-181. Gilbert, B. W., Haney, R. S., Crawford, F., McClellan, J., Gallis, H. A., Johnson, M. L. et al. (1977). Two-dimensional echocardiographic assessment of vegetative endocarditis. Circulation, 55, 346-353. Mardelli, T. J., Ogawa, S., Hubbard, F. E., Dreifus, L. S. & Meixell, L. L. (1978). Cross-sectional echocardiographic detection of aortic ring abscess in bacterial endocarditis. Chest, 74, 576-578.
Scanlan, J. G., Seward, J. B. & Talik, A. J. (1982). Valve ring abscess in infective endocarditis: visualisation with wide angle two dimensional echocardiography. Amertcan Journal of Cardiology, 49, 1794-1800. Sheldon, W. H. & Golden, A. (1951). Abscesses of the valve rings of the heart, a frequent but not well recognised complication of acute bacterial endocarditis. Circulation, 4, 1-12. Utley, J. R. & Mills, J. (1972). Annular erosion and pericarditis. Complications of endocarditis of the aomc root. Journal of Thoraeic and Cardiovascular Surgery, 64, 76-81. Wong, C. M., Oldershaw, P. & Gibson, D. G. (1981). Echocardiographic demonstration of aortic root abscess after infective endocarditis. British Heart Journal, 46, 584-586.