Magnetic Resonance Imaging of a Pulmonary Autograft in the Mitral Position

A 40-year-old woman presented with shortness of breath and palpitations that had been progressing for the past 10 years. Clinical examination revealed severe mitral stenosis with severe pulmonary arterial and pulmonary venous hypertension. A transthoracic echocardiogram showed severe calcific mitral stenosis with a mitral valve area of 0.9 cm² and trivial aortic regurgitation. The patient underwent mitral valve replacement with a pulmonary autograft in January 2002; we used our previously described technique.^1,2 The right ventricular outflow tract was reconstructed using a 26-mm cryopreserved pulmonary homograft from our own valve bank. Eighteen months postoperatively, the patient was in New York Heart Association functional class I. Follow-up transthoracic echocardiography showed a mitral valve area of 4 cm² with no mitral stenosis or regurgitation.

Magnetic resonance imaging (MRI) was performed with use of a 1.5 Tesla MRI system (Sonata; Siemens, Germany). Morphologic imaging was performed with spin-echo T₁-weighted and half-Fourier single shot turbo spin-echo (HASTE) sequences with electrocardiographic and respiratory gating. Images were acquired in the axial, coronal, sagittal, and double-oblique planes (vertical 2-chamber long-axis and horizontal 4-chamber long-axis views for the mitral valve, and sagittal view for the pulmonary valve). Functional imaging was performed with gradient echo pulse sequence (true-FISP) cine images through the mitral valve (in the vertical and horizontal long-axis views) and the pulmonary valve (sagittal view). Sixteen frames per cardiac cycle were acquired. The T₁-weighted and the true-FISP (bright blood) images showed the pulmonary autograft in the mitral position, partly projecting into the left atrium (Fig. 1). There was no thrombus in the atrial cavity or the appendage. Cine MRI showed normally contracting left and right ventricles. The left ventricular ejection fraction was 0.52. A thin signal void arose from the replaced mitral valve in systole, seen only in the later part of the cardiac cycle and not extending to the periphery of the left atrium (Fig. 2). The regurgitant fraction by ventricular volumetric measurements was calculated to be 0.15, which indicated trivial mitral regurgitation. Cine imaging of the pulmonary valve showed normal valvular function. The right ventricular outflow tract and the pulmonary valve area appeared normal.

Fig. 1 Gradient echo pulse sequence (true-FISP) cine magnetic resonance image in the 4-chamber view (diastolic frame): the pulmonary autograft is shown in the mitral position (arrow). Note the level of the new “mitral valve,” which is higher than that of the tricuspid valve.

LA = left atrium; LV = left ventricle; RA = right atrium; RV = right ventricle

Fig. 2 Systolic frame of the cine magnetic resonance image in the same view as Figure 1: a thin signal void enters the left atrium from the autograft, which suggests trivial regurgitation.

LA = left atrium; LV = left ventricle; RA = right atrium; RV = right ventricle

Comment

The pulmonary autograft has been used for mitral valve replacement in patients with isolated mitral valve disease (Ross II procedure). In earlier publications, we reported the detailed surgical technique and early results of this procedure.^1,2 In this report, we present the MRI features of 1 such patient.

We present this case because of its unique features. The autograft remains wholly in the left atrium and extends at least 2 cm upstream of the mitral annulus. Therefore, the valve cusps of the autograft are at a higher level than the tricuspid valve, as seen on the MRI image. To the best of our knowledge, an MRI of a pulmonary autograft in the mitral position has not been published previously.