Echocardiographic characteristics of annulo-leaflet mitral ring

Abstract

Background: Annulo-leaflet mitral ring (ALMR) is a rare congenital cardiac anomaly caused by fibrous tissue on the atrial surface of the mitral valve, which can progress to cause severe stenosis. Because little information is available on the detailed echocardiographic features of the anomaly and their associations with surgical resection, this study was undertaken to address these questions.

Methods: A retrospective single-center study of clinical and echocardiographic data from patients with ALMR from 2004 through 2012 was conducted. Data were analyzed for associations with surgical resection.

Results: The median age at diagnosis of the 57 study patients was 1.8 years, and 63% were male. Isolated ALMR was found in six patients (11%). The remaining 51 patients (89%) had associated lesions: additional mitral valve abnormalities in 35 (61%), coarctation in 11 (19%), and subaortic stenosis in 15 (26%). ALMR was best visualized in the apical four-chamber view, and the lesion was indistinct from the parasternal long-axis view in 25% of patients. Seven patterns of ALMR were identified, differentiated by leaflet involvement (anterior, posterior, or both) and location (annular vs intraleaflet). Compared with other patterns, intraleaflet morphology had a higher mean mitral stenosis gradient than in patients without (8.4 vs 5.8 mm Hg, P = .01). Among the 57 patients, 32 (56%) underwent ALMR resection, at a median age of 1.5 years. Younger age at echocardiographic diagnosis (P = .02) and short chordae (P = .03) were associated with resection.

Conclusions: The morphology of ALMR as evaluated by echocardiography is heterogeneous and can be classified on the basis of lesion location and leaflet involvement. Intraleaflet morphology is associated with significant mitral stenosis; younger age at diagnosis and short chordae are associated with ALMR resection.

Keywords: Congenital heart disease; Pediatric cardiology; Shone’s complex; Supravalvar mitral stenosis.

Figure 1

Membrane extent index (MEI) measurements. The MEI is an average of anterior and posterior ALMR length compared to total leaflet length.

Figure 2

Diagram showing anatomic types of ALMR.

Figure 3

Echocardiographic examples of ALMR types.

Figure 4

Echocardiographic imaging of ALMR from the apical 4-chamber view with side-by-side display of 2-dimensional and color Doppler. The ALMR extends from the annulus onto the lumen with proximal attachments to the leaflet tissue (arrows). Color comparison (right panel) demonstrates flow acceleration beginning at the level of the obstructive tissue (arrows). LA, left atrium; LV left ventricle; arrows, ALMR.