Endomyocardial fibrosis is characterized by progressive fibrosis and thickening of the ventricular endocardium that result in restrictive cardiomyopathy. The prevalence of this disease is greater in tropical and subtropical countries where parasitosis is frequently encountered. Endomyocardial fibrosis can also be encountered in temperate countries and is then associated with hypereosinophilia as part of Löffler’s syndrome.
The disease process involves the left (30%), the right (10%), or both ventricles (60%). A thick fibrotic layer with scattered thrombi severely adherent to the ventricular endocardium typically begins at the apical level and then extends towards the outflow tracts and atrioventricular valves, involving first the papillary muscles and chordae and later the leaflets and annulus. The two most common consequences of this disease process are ventricular obliteration with restrictive diastolic filling and atrioventricular valve dysfunction.
The clinical picture is that of the absence of diastole, with progressively severe symptoms of pulmonary edema, peripheral edema, and hepatomegaly. Either mitral or tricuspid regurgitation, or both, is frequently present at a later stage.
On echocardiography, the most striking anomaly is the huge dilatation of the left or right atrium, or both atria, and the most characteristic finding is the apical obliteration and endocardial thickening of the ventricles. The most common mechanism of atrioventricular valve regurgitation is diastolic restricted leaflet motion (type IIIa). The posterior leaflet of the mitral valve or the septal leaflet of the tricuspid valve is commonly thickened and incorporated in the fibrotic process. Subvalvular involvement with chordae fusion and thickening and papillary muscle fibrosis may also be present. Occasionally anterior leaflet prolapse (type II) resulting from chordae elongation can also be observed. Finally, significant annular dilatation is a common secondary lesion in these patients.
Cardiac catheterization shows a restrictive diastolic filling pattern with a dip-plateau recording aspect in the right atrium, right ventricle, and pulmonary artery in patients with extensive right-sided disease. In patients with left-side involvement, elevated left ventricular end-diastolic pressure and pulmonary hypertension are common findings. Left ventricular angiography commonly shows an apical defect.
On magnetic resonance imaging, endomyocardial fibrosis is characterized by diffuse and intense hyperenhancement of the ventricular endocardium.
Histological findings show significant fibrotic thickening of the ventricular endocardium with infiltration of fibrous tissue in the underlying myocardium. During the evolution of the disease, calcification of the fibrotic process is a common observation. In addition, thrombus formation covering the surface of the fibrotic layer may be observed.
SURGICAL MANAGEMENT
In 1971 Dubost first surgically treated this condition. The goal of the surgical procedure was to increase the size and the compliance of the ventricular cavity and to preserve or restore atrioventricular valve competence if necessary. Depending upon the extension of the lesions, the following two scenarios are possible.
Endocardial Fibrosis with Limited Extension to the Valvular Apparatus
In this situation, ventricular endocardiectomy is used to correct the fibrosis. Through the valve orifice, the fibrotic process obstructing the apex and the inflow chamber can be easily identified ( Fig. 32-1 ). Thrombus formation and even calcification are often present (a) . The fibrous process reaches the base or the body of the papillary muscles but spares the chordae and the leaflet tissue. With an approach through the valvular orifice, the dissection is initiated with the goal of creating a plane of cleavage between the fibrosis and the myocardium (b) . The thickened endocardium is peeled towards the ventricular apex where the adhesion to the myocardium is greatest. Particular care must be taken at this level to resect as little normal myocardial tissue as possible, considering that dissection in the wrong plane would cause ventricular perforation. After having removed the fibrotic process, the surgeon should continue with removal of the remaining endocardium up to the annulus and the outflow tract to prevent extension of the fibrosis (c) .
Endocardial Fibrosis with Involvement of the Valvular Apparatus
Even in this setting the valve can often be preserved if the leaflet tissue is still intact. Since the fibrotic process usually extends up to the annulus, the decortication is facilitated by temporary detachment of the posterior leaflet from the annulus. This provides direct access to the fibrotic process and the subvalvular apparatus, which can be dissected free from all fibrotic tissue. The continuity between the posterior leaflet and the annulus is restored either by directly attaching the leaflet or by using leaflet extension with a glutaraldehyde-preserved autologous pericardial patch. The height of the reconstructed posterior leaflet should be approximately 20 mm. Anterior leaflet dysfunction, if present, is best treated by secondary chordae transposition or artificial chordae. A remodeling annuloplasty is performed in all cases since the annulus is often dilated and always fragile as a result of the endocardial resection.
If the disease process involves the right side of the heart, it is recommended that a thin layer of fibrosis be left in the area of the conduction tissue to avoid postoperative atrioventricular block. If during preoperative investigation the disease process seems limited to the left ventricular cavity, the right ventricle must still be systematically explored. It is not unusual to observe the beginning of a similar fibrotic process near the apex that requires excision. If there is no visible pathological process, the tricuspid orifice should be measured and compared to the measurement of the surface area of the “antero-posterior leaflet” delineated by exerting traction on the anterior papillary muscle (see Fig. 19-5 ). If the annulus is one size larger than the size that covers the exposed anteroposterior leaflet tissue, a ring should be implanted.
In patients with advanced valvular lesions, a reconstructive procedure may not be feasible and a conventional valve replacement is required.
After the surgery and during the follow-up period, eosinophil counts should be carefully assessed and hypereosinophilia treated as well as occasional parasitosis to avoid recurrence.
Taking into consideration the excellent long-term results of the surgical excision of endocardial fibrosis, it is advisable to perform surgery as early as possible, before extensive involvement of the valvular apparatus—that is, as soon as the diagnosis has been established and the apical obstruction has been documented.
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