Surgical repair remains the primary treatment modality for VSD [1,2,3,4]. Accurate assessment of VSD size and location is critical in formulating a surgical plan. TTE is the most commonly used preoperative examination for congenital heart defects, acclaimed for its ease of use, non-invasiveness, and independence from heart rate variability. Numerous studies, as well as our own findings, affirm that TTE can accurately measure the size and location of VSD, alongside dynamically assessing heart valve function, cardiac contractility, and pulmonary artery pressure. This comprehensive evaluation is particularly crucial in cases of cardiac malformations [6, 8, 16].

This study demonstrated that the size and location of VSD as measured by TTE were consistent with intraoperative findings, indicating high accuracy in diagnosing VSD and other intracardiac malformations. However, TTE has its limitations: (1) It produces two-dimensional images, necessitating the synthesis of multiple sections for a three-dimensional conceptualization of VSD. (2) Its diagnostic accuracy is influenced by the sternum and lungs and depends greatly on the cardiac sonographer’s skill and experience, affecting its reproducibility and utility. (3) TTE’s ability to assess extra-cardiac vascular diseases is limited, which is significant considering the prevalence of extra-cardiac vascular complications in infants with VSD. (4) TTE cannot evaluate tracheal conditions. For instance, in this study, three patients diagnosed with mild aortic stenosis by TTE prior to surgery for coarctation of the aorta displayed more severe conditions intraoperatively. Additionally, nine patients had tracheal stenosis, a condition undetectable by TTE.

In recent years, cardiac CTA has experienced significant technological advancements, enabling detailed cardiac structural scanning and reconstruction for congenital heart disease with reduced radiation exposure [17, 18]. Its superior spatial and temporal resolution, short scan duration, prospective ECG gating, and advanced iterative reconstruction post-processing make cardiac CTA an excellent tool for the morphological assessment of congenital heart diseases. Notably, it can effectively visualize the three-dimensional morphology of VSD and its spatial relationship with surrounding tissues. This study found that cardiac CTA’s measurements of VSD size and location align with intraoperative findings, confirming its accuracy in delineating these parameters. Furthermore, cardiac CTA is considered the gold standard for diagnosing vascular malformations, offering precise representations of adjacent large vessels. It also provides valuable images of the trachea and lungs, aiding in the evaluation and detection of related diseases. However, the potential for radiation exposure remains a concern [19, 9]. Studies have indicated DNA damage and cell apoptosis at exposures exceeding 7.5 mSv [20]. To mitigate this risk, we employed low-tube voltage, prospective ECG gating, and iterative reconstruction techniques, achieving low-dose scans with radiation levels between 0.48 and 4 mSv. Despite these advances, cardiac CTA cannot dynamically assess heart valve conditions, pulmonary artery pressure, or cardiac contractility. Additionally, performing cardiac CTA in infants often requires sedation due to the need for patient cooperation during the procedure.

TTE and cardiac CTA each have distinct advantages and limitations in diagnosing congenital heart disease. In our survey focusing on the preoperative examination of infants with VSD, three surgeons opined that only TTE was necessary before surgery, deeming cardiac CTA unnecessary. Conversely, seven surgeons recommended a combination of both TTE and cardiac CTA for preoperative evaluation. None believed that cardiac CTA alone was sufficient. Although cardiac CTA provides accurate assessments of VSD size and location, it produces mainly static images and lacks the capability to dynamically monitor cardiac functions like valve activity, pulmonary artery pressure, and cardiac contractility, as TTE does. All surveyed cardiac surgeons agreed that cardiac CTA alone was inadequate for preoperative evaluation. However, two surgeons felt that preoperative CTA was not essential, stipulating that TTE must be performed by a highly skilled cardiac sonographer and should be supplemented with a lung CT scan to rule out pulmonary and tracheal issues. The majority, eight surgeons, advocated for the combined use of TTE and cardiac CTA before surgery. They believed this approach would leverage the strengths of both modalities, enabling accurate assessments of VSD’s size, location, and three-dimensional shape, identifying other cardiac and tracheal malformations, and facilitating comprehensive preoperative planning.

This study has certain limitations that must be considered. Firstly, it is a retrospective analysis with a relatively small sample size, which may affect the generalizability of the results. Secondly, the measurement of VSD sizes during surgery, performed in a state of cardiac arrest, might be influenced by nonphysiological dilation of the ventricles. This factor could introduce a bias in the assessment of VSD dimensions.