|Number 15-11: CMR is the Technique to Evaluate Anatomically Corrected...|
Number 15-11: Cardiac magnetic resonance is the technique to evaluate anatomically corrected malposition of the great arteries
Case from: Lamia Ait-Ali*§,MD, PhD, Bruno Murzi†, MD, MD, Pierluigi Festa§ ‡, MD
Institute: *Institute of Clinical Physiology, CNR, Massa-Pisa, Italy, § Pediatric Cardiology and GUCH unit, †Pediatric cardiac surgery, Heart hospital, Fondazione G. Monasterio-CNR, Regione Toscana, Massa, Italy. ‡ MRI Laboratory Fondazione G. Monasterio-CNR, Regione Toscana Pisa, Italy
A symptomatic 50 year old woman previously diagnosed as congenitally corrected transposition of great arteries (L-TGA) was referred to our department. She was overweight and complained shortness of breath and palpitations.
Basal echocardiogram showed a situs solitus, levocardia, a small restrictive ventricular septal defect (VSD), associated to a mild sub-pulmonary stenosis and a severe sub-aortic tunnel –like stenosis with the aorta lying anteriorly and to the left of the pulmonary artery and finally two hypertrophied ventricles; however because of a bad acoustic window, the AV valve and ventricles morphology were not well identified. She was scheduled for Cardiac Magnetic Resonance (CMR) evaluation.
At CMR the following features were found: -the left side sided AV valve was bileaflet , therefore consistent with a mitral valve (Fig. 1; movie 1,2) and a morphological tricuspid valve was identified on the right side (atrio-ventricular concordance)
Fig 1: Still image and cine SSFP short axis ventricle (movie 1), 4 chamber view (movie 2): typical mitral valve (white arrow) connected to a posterior left ventricle. LA: left atrium; LV: Left ventricle.
-a sub-pulmonary VSD (Fig. 2) leading to a left-to-right shunt with QP/QS evaluated as 2;
Fig 2: Black blood MR of right ventricle outflow tract showing a sub-pulmonary ventricular septal defect
VSD: ventricular septal defect; PA: pulmonary artery.
- both great arteries abnormally arising above the appropriate ventricles (ventriculo-arterial concordance) with conal tissue beneath each great artery, resulting in aortic-mitral and pulmonary-tricuspid discontinuity; the aorta arises form the posterior hypertrophic left ventricle (LV) through a stenotic fibro-muscular tunnel, lying anterior and to the left of the pulmonary artery ; the last arises from the anterior RV with a mild sub-valvular stenosis (Fig 3, 4; movies 3,4,5).
Fig 3, movie 3: Cine SSFP showing anterior aorta arising form the posterior LV through a stenotic fibromuscular tunnel (white arrow)
AO: aorta; LV: Left ventricle.
Fig 4, movie 4: Sagittal Cine SSFP showing anterior aorta arising form the posterior LV and a posterior pulmonary artery arising from the anterior RV
AO: aorta; LA: left atrium; LV: left ventricle; PA: pulmonary artery.
Movie 5: Axial stack showing the relations of the ventricles to the corresponding great vessels.
Conclusion : CMR diagnosis was Anatomically corrected malposition of the great arteries (ACMGA) - VSD- sub aortic and sub pulmonary stenosis. A cardiac catheterization confirmed the severe sub-aortic stenosis with a LV-Ao gradient of 60 mmHg, moderate sub-pulmonary stenosis (RV-PA gradient 30 mmHg), and a restricted VSD with QP/QS = 2. Surgical report confirmed the CMR diagnosis, therefore bilateral miectomy to relieve LVOT and sub-pulmonary obstruction was performed and the VSD was also closed by means of an autologous treated pericardial patch. Post–op CMR (Fig 5) illustrates the good surgical result.
Fig 6: Post operative CMR
A) Cine SSFP left outflow tract
B) Cine SSFP right outflow tract
AO: aorta; LV: Left ventricle; PA: pulmonary artery: RV: right ventricle.
Perspective: CMR was critical to obtain the correct diagnosis of ACMGA, restrictive VSD, subaortic and subpulmonary stenosis. ACMGA is a very rare form of congenital heart disease in which the great arteries arise above the anatomically correct ventricles but are abnormally related to the ventricles and to each other [1,2]. Subaortic stenosis occurs in about 15% of ACMGA . ACMGA is frequently misdiagnosed as congenitally corrected transposition (L-TGA)[4,5] however because of the technical problem of the ventricular septal defect closure to avoid the conduction pathway, they must be differentiated precisely . CMR should be the preferred technique in this setting because it is radiation-free, has a high anatomic definition and overcomes some of the limitations of ultrasound mainly in adult patients.
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