A three-dimensional printed model in preoperative consent for ventricular septal defect repair

This study was approved by the Institutional Review Board at our institution (Reference Number: HCHLL-2018-02). The study was prospective, two arms, single center, and randomized. The randomization of patients was performed using an equation established from rand() function in Microsoft Excel (Microsoft Corporation, Seattle, WA, USA). All subjects were enrolled and consented in the study by the same surgeon, followed by a questionnaire to fill out. Since our patients were all minors, their parents were approached for decision-making. From January 2018 to January 2019, guardians of 44 patient candidates for elective perimembranous VSD repair were approached, and 40 were included. Four were excluded for conversion to device closure (n = 1), refusal to participate outright (n = 2), or not being able to understand the study (n = 1). No included patient had previously undergone any interventional therapy or open-heart surgery. The control group had the information about their disease, the anatomy of the defect and surgical indications and potential complications explained by a surgeon using the current standard of clinical care, including 2D charts downloaded from the Internet and verbal explanation. The study group had the same information given to them using a 3D printed model of a heart with perimembranous type VSD to help explain the lesion’s anatomy, surgical procedure and potential complications. The same model was used throughout the study. Immediately after communication, a Likert-type questionnaire with 3 question items (the questionnaire was designed and approved by all authors and included understanding of VSD anatomy, of procedure and its complications, and overall understanding of the consent process focusing on verbal and visual aid-assisted communication) with a scale from 1 to 10 for each item as well as an additional item exclusively for experimental group regarding the usefulness of the 3D print from the guardians’ perspective was required to complete. The questionnaires also collected information of the guardian’s ages, genders and education level, which were self-reported by them. The whole process was conducted by the same surgeon throughout the study. Additionally, perioperative data of patients as well as other relevant information were collected from patient records.

Pre-existing CT data obtained with a SOMATOM Force scanner (Siemens Healthineers, Munich, Germany) was used for 3D printed model production. The patient from whom the CT data was obtained was initially suspected to have coarctation of the aorta in addition to an explicit perimembranous VSD, though later CT scan dismissed this coarctation suspicion. CT slice thickness ranged from 0.5 to 1.0 mm and pixel spacing ranged from 0.5 to 1.0 mm. The CT data of a previous patient was selected and opened in Mimics software (Materialise, Leuven, Belgium). The segmentation was achieved using intensity value threshold followed with semi-automated and manual maneuver. The following blood volume subsets were segmented: left atrium with pulmonary veins, right atrium with vena cava, left ventricle, right ventricle, pulmonary arteries, aorta, and ascending aorta with coronary arteries. Additional segments included the VSD. All volumes outside of the volume of interest were masked. The result was exported from Mimics as a.stl file and imported for printing on an RS6000 printer (Alliance 3D Printing Technology, Shanghai, China) using photosensitive resin with a glossy finish.

This study was approved by the Institutional Review Board at our institution (Reference Number: HCHLL-2018-02). All research was performed in accordance with relevant guidelines/regulations. Written informed consent was waived by the ethics committee due to minimal risk and the need to prevent full disclosure that may have induced bias and participation was voluntary. The study did not involve any use of human tissue samples.

As abovementioned, the study population is relatively small and only included perimembranous VSD subjects, limiting the generalizability of the results. Usually, CT or MRI scan is not used in diagnosing an isolated VSD for echocardiography is almost always enough and also to avoid unnecessary radiation or sedation, making data source for VSD 3D printing difficult to obtain. Since every lesion is unique, even for the same type of heart defect, the single 3D printed model obviously could not completely represent specific characters of each patient’s heart defect, such as variance in sizes, locations of the VSD. Moreover, the associated lesions, including patent foramen ovale, atrial septal defect, patent ductus arteriosus, right ventricular outflow tract stenosis, tricuspid and mitral regurgitation that need repair concomitantly could not always be well demonstrated on the model, especially the relationship between tricuspid valve and the defect due to poor image definition of valvular structures obtained from CT scan. We chose perimembranous VSD for study as it was the most common type of CHD. In view of the low incidence and wide variance of most of the other CHDs, it is difficult to use one replica for all patients of a specific lesion. The survey focused on young guardians’ response to the 3D models in a hospital setting, without any further follow-up, so the impact on post-discharge satisfaction of medical/surgical care or improved quality of life cannot be obtained. The consent process was also performed by the same surgeon who performed the operations, so there was inevitably a conflict of interest while filing the questionnaires for the family, though we consider it could have exerted the same effect in the two groups. In addition, to increase the response rate of the survey we did not objectively assess the impact of the models on learning and knowledge acquisition.