Morphological analysis and preoperative simulation of a double-chambered right ventricle using 3-dimensional printing technology

CASE REPORT – ADULT CARDIAC Interactive CardioVascular and Thoracic Surgery 22 (2016) 688–691 doi:10.1093/icvts/ivw009 Advance Access publication 9 February 2016 Cite this article as: Shirakawa T, Koyama Y, Mizoguchi H, Yoshitatsu M. Morphological analysis and preoperative simulation of a double-chambered right ventricle using 3-dimensional printing technology. Interact CardioVasc Thorac Surg 2016;22:688–91. Morphological analysis and preoperative simulation of a doublechambered right ventricle using 3-dimensional printing technology Takashi Shirakawaa,*, Yasushi Koyamab, Hiroki Mizoguchia and Masao Yoshitatsua a b Department of Cardiovascular Surgery, Kansai Rosai Hospital, Amagasaki, Japan Department of Diagnostic Radiology and Cardiology, Sakurabashi Watanabe Hospital, Osaka, Japan * Corresponding author. Department of Cardiovascular Surgery, Kansai Rosai Hospital, 3-1-69 Inabaso, Amagasaki, Hyogo 660-8511, Japan. Tel: +81-6-64161221; fax: +81-6-64191870; e-mail: (T. Shirakawa). Received 22 October 2015; received in revised form 23 December 2015; accepted 11 January 2016 Abstract We present a case of a double-chambered right ventricle in adulthood, in which we tried a detailed morphological assessment and preoperative simulation using 3-dimensional (3D) heart models for improved surgical planning. Polygonal object data for the heart were constructed from computed tomography images of this patient, and transferred to a desktop 3D printer to print out models in actual size. Medical staff completed all of the work processes. Because the 3D heart models were examined by hand, observed from various viewpoints and measured by callipers with ease, we were able to create an image of the complete form of the heart. The anatomical structure of an anomalous bundle was clearly observed, and surgical approaches to the lesion were simulated accurately. During surgery, we used an incision on the pulmonary infundibulum and resected three muscular components of the stenosis. The similarity between the models and the actual heart was excellent. As a result, the operation for this rare defect was performed safely and successfully. We concluded that the custom-made model was useful for morphological analysis and preoperative simulation. Keywords: Double-chambered right ventricle • Morphology • 3D model • 3D printer CASE REPORT A 67-year old woman, 4 years after aortic valve replacement (AVR), presented with gradually progressive dyspnoea on exertion. The patient was diagnosed with a congenital heart disease and had limited physical activity during her school years. The first symptom occurred at the age of 63. Transthoracic echocardiography (TTE) revealed severe aortic regurgitation with dilated left ventricular diameters at end-diastole/systole (LVDd/Ds) and reduced ejection fraction (LVEF): LVDd/Ds 60/45 mm and LVEF 51%. The TTE also suggested a pressure gradient through the right ventricular outflow tract (RVOT) of as low as 17 mmHg and a small atrial septal defect (ASD) represented by a tiny colour Doppler jet. AVR was performed with a 19-mm bileaflet mechanical valve. This time, TTE showed that the pressure gradient reached 87 mmHg at the RVOT and improved left ventricular parameters: LVDd/Ds 41/26 mm and LVEF 67%. Right-heart catheterization showed two different pressures, 94 and 25 mmHg, in the right ventricle (Video 1). The patient was diagnosed with doublechambered right ventricle (DCRV) that needed surgical repair. Cardiac computed tomography (CT) revealed thickened structures around the RVOT (Fig. 1A). However, because the detailed structures were difficult to understand on a flat computer screen, we made 3D models focusing on the obstructive bundle. We used Video 1: Right-heart catheterization showing the stenosis at the right ventricular outflow tract. © The Author 2016. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved. T. Shirakawa et al. / Interactive CardioVascular and Thoracic Surgery 689 OsiriX MD (Pixmeo, Geneva, Switzerland) and UP! Plus 3D printer (Tiertime Technology, Beijing, China) with acrylonitrile butadiene styrene resin. To maintain the validity of the 3D polygonal data and models, medical staff performed all the work processes in the hospital (Fig. 1B and Video 2). The anatomy was readily identified with these 3D models (Fig. 1C and D). Furthermore, we simulated the surgical view through an incision at the pulmonary infundibulum (Fig. 2A). Surgery was performed through median sternotomy. Cardiopulmonary bypass was established with an aortic cannula in the ascending aorta and bicaval cannulation. We used blood cardioplegia. The incision was made on the pulmonary infundibulum as simulated. The similarity between the models and the actual heart was excellent. The obstructive bundle was carefully resected until the stenosis was sufficiently reduced, and the incision was closed with a bovine pericardium patch (Fig. 2B). The ASD was directly sutured. The operation time was 311 min. On the 7th postoperative day, the pressure gradient and ASD disappeared on TTE, and the RVOT was enlarged on CT. After being discharged on the 36th day, the patient had no symptom or recurrence on outpatient TTEs for over a year. Pathological examination showed that the resected bundle included both ventricular muscle cells with hypertrophic change and tendon tissue. The hypertrophy was caused by a haemodynamic change rather than by a primary muscle change, e.g. cardiomyopathies. There was no sign of infection. DISCUSSION DCRV is a rare heart defect in which an anomalous muscle bundle separates the right ventricle into a high-pressure chamber and a low-pressure chamber. The bundle develops over time and typically presents in childhood or, rarely, in adulthood. Video 2: 3D polygonal data made from CT images by using surface rendering technique. CT: computed tomography. Various mechanisms have been proposed. Maron et al. [1] reported microscopic observations of muscular cells resected from the supraventricular crest (SVCT) and suggested that increased blood flow with ventricular septal defect would stimulate localized muscular hypertrophy. Wong et al. [2], based on echocardiographic measurements, proposed that superior displacement of the moderator band (MB, known as the septomarginal trabecula) caused the obstruction. In contrast, Alva et al. [3] described the anomalous muscle bundle as the accentuated septoparietal trabecula (SPT). Key structural relationships are shown clearly in our diastolic 3D model: the SVCT forms a paraseptal wall; the SPT and MB are the accentuated shelves dividing the RVOT; and the MB and SVCT make a ridge at the proximal ostium of the stenosis (Fig. 1C). The stenosis in systole was a narrow pathway sandwiched between the SPT and SVCT, where the MB seemed to support the SPT from below (Fig. 1D). We concluded that a single muscular component CASE REPORT Figure 1: Images (...truncated)