Morphological Assessment of Single-Ventricle Atrioventricular Valve Regurgitation on Dual-Source 128-Slice Multidetector Computed Tomography and 4-Dimensional Imaging

Following Fontan procedure, an 8-year-old boy was diagnosed with severe atrioventricular valve regurgitation and poor ventricular function at routine follow-up on transthoracic echocardiography. He was previously diagnosed with tricuspid atresia with ventriculoarterial discordance (type IIc) and completed a staged Fontan operation with Damus-Kaye-Stansel anastomosis at 3 years of age. His parents stated that he had substantially reduced tolerance to exercise compared with his classmates. On cardiopulmonary exercise test, peak V̇O₂ was 21.3 ml/kg/min, which was 50% of the normal level according to the sex- and age-matched institutional reference value. Cardiac catheterization and magnetic resonance imaging (MRI) confirmed the severity of the atrioventricular valve regurgitation, and surgical repair was scheduled. On attempt to clarify the morphology of the valve and etiology of the regurgitation prior to surgery, this was difficult to visualize on transthoracic and transesophageal echocardiography (3-D transesophageal echocardiography was unavailable because of the patient’s low weight: 17 kg). MRI was also unable to show the fine structure of the valve. Subsequently, dual-source 128-slice multidetector computed tomography (CT; Siemens SOMATOM Definition Flash) and 4-D imaging were performed. Data were reconstructed in 20 separate phase increments encompassing the entire cardiac cycle, ranging from 0% to 95% with a 1.0-mm slice thickness. The cine image clearly showed a morphologically left ventricle because of the presence of 2 papillary muscles on the free wall and the absence of the conus (Figure 1; Movie S1). Interestingly, a large anterior cleft with partially reduced coaptation of the mitral valve was also clearly shown and was considered to be the source of severe regurgitation (Figure 2; Movie S2). Intraoperative findings were consistent with the clear CT image; the cleft closure was successfully performed. The patient was discharged on postoperative day 32 in good condition.

Figure 1.

(A) Systolic and (B) diastolic phase of the coronal image of the main ventricle. The systemic ventricle was diagnosed as the left ventricle because of the existence of 2 papillary muscles on the free wall, fine trabeculation, and undeveloped infundibulum. LAA, left atrial appendage; nAO, neo-aorta; oAO, original aorta; PM, papillary muscle; RV, right ventricle; VSD, ventricular septal defect.

Figure 2.

(A) Systolic and (B) diastolic phase of the horizontal image of the atrioventricular valve. The cine image clearly shows a large anterior mitral cleft with partially reduced coaptation. AC, anterior cleft; nAO, neo-aorta; oAO, original aorta; PML, posterior mitral leaflet; PV, pulmonary vein.

According to a previous study, the morphological characteristics of isolated mitral cleft without a primum septal defect differ according to whether or not the ventriculoarterial discordance exists. Van Praagh et al reported that the cleft attachment was on the left ventricular free wall in the case of ventriculoarterial discordance, while the attachment was on the ventricular septal defect and membranous septum in the case of normally related great arteries.¹ In the present case, the atrioventricular valve appeared to have 3 leaflets. Although atrioventricular valve with 3 leaflets is typically considered to be the tricuspid valve, in the present case, because the ventricle was morphologically the left ventricle and the cleft direction was consistent with the aforementioned study, this atrioventricular valve was determined to be the mitral valve.

Computed tomography is useful in assessing mitral valve morphology² and is considered to be highly valuable, particularly when 3-D transesophageal echocardiography is not able to be used, but although the information obtained from CT is extremely valuable, radiation exposure is a major concern, particularly in pediatric cases. In this case, the effective CT dose using the previously reported estimation³ was 16.7 mSV.

Because the surgical repair of the atrioventricular valve in single-ventricle cases is frequently difficult, detailed preoperative assessment is essential to determine the possibility of surgical correction. Thus, we suggest that 4-D imaging of the atrioventricular valve using CT can be an important option for single-ventricle cases, particularly when morphology is difficult to visualize with other modalities.

Acknowledgements

The authors would like to thank Joji Hashimoto for technical assistance in the imaging.

Disclosures

The authors declare no conflicts of interest.

Supplementary Files

Supplementary File 1

Movie S1. Cine image of the main ventricle.

Supplementary File 2

Movie S2. Cine image of the atrioventricular valve with anterior cleft.

Please find supplementary file(s);

http://dx.doi.org/10.1253/circj.CJ-16-0083

References

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