A new low-cost method of virtual cardiac dissection of computed tomographic datasets

Clarifying the Anatomy of Tetralogy of Fallot with S-shaped Ascending Aorta

We recently encountered several cases of tetralogy of Fallot with an abnormally oriented S-shaped ascending aorta. In this retrospective study, we sought to clarify morphology of this unusual under-recognized variant. Databases were reviewed to identify all patients with tetralogy of Fallot having an S-shaped ascending aorta. Computed tomographic angiography was used for the assessment of cardiac morphology. Out of the 21 patients, 18 (86%) had a right aortic arch, 2 (9%) had a left aortic arch, and the remaining patient (5%) had a double aortic arch. Patients with a right aortic arch, compared to age and sex-matched patients with a right aortic arch but normally oriented ascending aorta, had lesser aortic override (29.3 ± 14% vs 54.8 ± 13.2%; p = 0.0001) and a wider ascending aorta (25.2 ± 6.9 vs 18.0 ± 3.2 mm; p = 0.0003). The S-shaped ascending aorta was located posteriorly, with a higher sterno-aortic distance (25.5 ± 7.7 vs 9.9 ± 4.5 mm; p = 0.0001). The ascending aorta among patients with tortuosity was longer (4.12 ± 1.7 vs 3.07 ± 0.82, p = 0.03) but with similar tortuosity index (1.22 ± 0.19 vs 1.15 ± 0.17, p = 0.23). Of the cases with right aortic arch and S-shaped ascending aorta, 16 (89%) had extrinsic compression of the right pulmonary artery (p = 0.0001), while 7 (39%) had crossed pulmonary arteries (p = 0.008), with no such findings among those with normally oriented ascending aorta. Tetralogy of Fallot with an S-shaped ascending aorta is a variant with lesser aortic override and a more posteriorly located ascending aorta. Compression of the right pulmonary artery and crossed pulmonary arteries is frequent in the presence of a right-sided aortic arch. These findings have important implications for optimal diagnosis and surgical repair.

Intracardiac Three-Dimensional Image as Surgical Decision-Making Tool of Congenital Heart Disease

This study aimed to evaluate the anatomical reproducibility of a preoperative intracardiac 3D image (IC image) created using computed tomography, and to investigate its usefulness as a surgical decision-making tool. Between 2012 and 2022, ventricular septal defect (VSD) patients, and double outlet right ventricle (DORV) or transposition of the great arteries (TGA) with pulmonary stenosis (PS) patients who underwent cardiac surgery and had preoperative computed tomography were enrolled. SYNAPSE VINCENT® (Fujifilm) was used to create an IC image which was analyzed retrospectively. In 14 VSD patients, the diagnostic consistency rate in the Soto classification with intraoperative findings was 100% (14/14) for IC image versus 64% (9/14) for transthoracic echocardiography (P = 0.04). The defect size showed a higher correlation coefficient with IC image (0.837, P = 0.001) than with transthoracic echocardiography (0.567, P = 0.034). In 11 DORV/TGA with PS patients, the diagnostic consistency rate in the Lev classification was 100% (9/9) for IC image versus 77% (7/9) for transthoracic echocardiography (P = 0.47). The secondary interventricular foramen (SVF)/left ventricular outflow tract (LVOT) ratio by IC image was significantly smaller in the biventricular-repair group (median 0.71, IQR 0.67-1.06) than in the univentricular-repair group (median 1.79, IQR 1.53-2.42) (P = 0.006). An IC image is useful as a surgical decision-making tool for simple VSDs and complex congenital heart diseases such as DORV or TGA with pulmonary stenosis. The SVF/LVOT ratio determined from the IC image may be a useful indicator for avoiding LVOT obstruction.

Anaglyph stereo virtual dissection: a novel inexpensive method for stereoscopic visualisation of intracardiac anatomy on CT angiogram

Three-dimensional visualisation is invaluable for evaluating cardiac anatomy. Patient-specific three-dimensional printed models of the heart are useful but require significant infrastructure. The three-dimensional virtual models, derived from 3D echocardiography, computed tomographic (CT) angiography or cardiac magnetic resonance (CMR), permit excellent visualisation of intracardiac anatomy, but viewing on a two-dimensional screen obscures the third dimension. Various forms of extended reality, such as virtual reality and augmented reality, augment the third dimension but only using expensive equipment. Herein, we report a simple technique of anaglyph stereoscopic visualisation of three-dimensional virtual cardiac models. The feasibility of achieving stereovision on a personal computer, using open-source software, and the need for inexpensive anaglyph glasses for viewing make it extremely cost-effective. Further, the retained depth perception of resulting stereo images in electronic and printed format makes sharing with other members of the team easy and effective.

Use of advanced cardiac imaging in congenital heart disease: growth, indications and innovations

PURPOSE OF REVIEW

Significant improvements in the diagnosis and management of patients with congenital heart disease (CHD) have led to improved survival. These patients require life-long noninvasive evaluation. The use of advanced imaging such as cardiac magnetic resonance imaging (CMR) and cardiac computed tomography (CCT) has increased to support this need. The purpose of this review is to discuss the basics of advanced cardiac imaging, indications and review the recent innovations.

RECENT FINDINGS

Recent literature has demonstrated the increasing reliance of advanced imaging for CHD patients. In addition, research is focusing on CMR techniques to shorten scan time and address previous limitations that made imaging younger and sicker patients more challenging. CCT research has involved demonstrating high-quality images with low radiation exposure. Advances in digital technology have impacted the interactivity of 3D imaging through the use of virtual and augmented reality platforms. With the increased reliance of advanced imaging, appropriate use criteria have been developed to address possible under or over utilization.

SUMMARY

The utilization of advanced cardiac imaging continues to increase. As CMR and CCT continue to grow, increased knowledge of these modalities and their usage will be necessary for clinicians caring for CHD patients.

Clarifying the anatomy of the superior sinus venosus defect

OBJECTIVES

We sought to clarify the variations in the anatomy of the superior cavoatrial junction and anomalously connected pulmonary veins in patients with superior sinus venosus defects using computed tomographic (CT) angiography.

METHODS

CT angiograms of 96 consecutive patients known to have superior sinus venosus defects were analysed.

RESULTS

The median age of the patients was 34.5 years. In seven (7%) patients, the defect showed significant caudal extension, having a supero-inferior dimension greater than 25 mm. All patients had anomalous connection of the right superior pulmonary vein. The right middle and right inferior pulmonary vein were also connected anomalously in 88 (92%) and 17 (18%) patients, respectively. Anomalous connection of the right inferior pulmonary vein was more common in those with significant caudal extension of the defect (57% vs 15%, p=0.005). Among anomalously connected pulmonary veins, the right superior, middle, and inferior pulmonary veins were committed to the left atrium in 6, 17, and 11 patients, respectively. The superior caval vein over-rode the interatrial septum in 67 (70%) patients, with greater than 50% over-ride in 3 patients.

CONCLUSION

Anomalous connection of the right-sided pulmonary veins is universal, but is not limited to the right upper lobe. Not all individuals have over-riding of superior caval vein. In a minority of patients, the defect has significant caudal extension, and anomalously connected pulmonary veins are committed to the left atrium. These findings have significant clinical and therapeutic implications.

Systolic excursion of the leaflets of the truncal valve: An unusual mechanism for pulmonary stenosis in common arterial trunk

Background:

Pulmonary stenosis in patients with common arterial trunk protects the pulmonary vasculature. In our recently published prospective study of common arterial trunk, some patients with sinusal origin of the pulmonary arterial segment had pulmonary stenosis induced by systolic excursion of a truncal valvar leaflet. We aimed to determine the detailed morphologic characteristics of this unusual finding.

Methods and Results:

All 70 patients underwent echocardiography and computed tomographic angiography as per predefined study protocol. In selected cases, we also performed cardiac catheterization. Among 27 patients with aortic dominance, we found sinusal origin of the pulmonary arterial segment. In 5 of these patients, pulmonary stenosis was induced by systolic excursion of a truncal valvar leaflet. In all these patients, the truncal valve was trisinusate, albeit with asymmetric sinuses. The pulmonary arterial segment arose from the largest left sinus with its relatively large leaflet obstructing the pulmonary orifice during systole. In the remaining 22 patients, without pulmonary stenosis but with sinusal origin of pulmonary arterial segment, the truncal valve was quadrisinusate in 7, bisinusate in 2, and trisinusate in 13. None of the patients with quadrisinusate and bisinusate truncal valves had pulmonary stenosis. Among the 13 patients with trisinusate valves, the sinuses of the truncal valve were symmetrical in 6, while in 7, the pulmonary orifice originated from a smaller asymmetric sinus.

Conclusion:

Pulmonary stenosis, produced by a relatively large leaflet of an asymmetric truncal sinus, may prevent early development of pulmonary vascular disease. Timely recognition of this unusual mechanism of pulmonary stenosis is important for optimal management.

Virtual Dissection: Emerging as the Gold Standard of Analyzing Living Heart Anatomy

Traditionally, gross cardiac anatomy has been described mainly based on the findings in the dissection suite. Analyses of heart specimens have contributed immensely towards building a fundamental knowledge of cardiac anatomy. However, there are limitations in analyzing the autopsied heart removed from the thorax. Three-dimensional imaging allows visualization of the blood-filled heart in vivo in attitudinally appropriate fashion. This is of paramount importance for not only demonstration of cardiac anatomy for educational purposes, but also for the detailed anatomical evaluation in patients with acquired and congenital heart disease. In this review, we discuss the advantages of three-dimensional imaging, specifically focusing on virtual dissection, a volume rendering-based reconstruction technique using computed tomographic data. We highlight examples of three-dimensional imaging in both education and guiding patient management.

Imaging Modalities in Congenital Heart Disease

Cardiac imaging provides invaluable guidance at all stages of the management of congenital heart disease. Advances in the field of cardiac imaging have contributed immensely to improved outcomes of these patients. Echocardiography remains the first-line imaging modality. Non-invasive cross-sectional imaging using computed tomography and magnetic resonance imaging supplements morphologic and physiologic evaluation and are being increasingly used for diagnosis and follow-up of patients with a malformed heart. Cardiac catheterization, being invasive, is mostly reserved for accurate assessment of hemodynamic status and percutaneous interventions. Simultaneous improvement in visualization techniques has amplified the information obtained from various imaging modalities. This review provides an overview of cardiac imaging and visualization techniques commonly used in the diagnosis and management of patients with congenital heart disease.

Utility and Access to 3-Dimensional Printing in the Context of Congenital Heart Disease: An International Physician Survey Study

Background

Three-dimensional (3D) printing is a new technology capable of producing patient-specific 3D cardiac models.

Methods

A cross-sectional survey of pediatric cardiologists was conducted. Members of the Canadian Pediatric Cardiology Association and Congenital Cardiac Interventional Study Consortium were invited to participate. A questionnaire was distributed using Research Electronic Data Capture between May and September 2019. Results were analyzed using descriptive statistics, Fisher exact test, and odds ratio.

Results

A total of 71 pediatric cardiologists responded. Some 85% (60/71) agreed that patient-specific 3D printed cardiac models are a beneficial tool in treating children with congenital heart disease (CHD); 80% of those (48/60) believe 3D models facilitate communication with colleagues; 49% (35/71) of respondents had access to 3D printing technology; and 77% (27/35) of those were using models for clinical care. Access differed according to geographic location (P = 0.004). Of respondents, Americans were 5.5 times more likely (confidence interval, 1.6-19.2) than Canadians to have access to 3D printing technology. The primary reason for lack of access was financial barriers (50%, 18/36). In clinical practice, surgical planning is the primary use of models (96%, 26/27), followed by interventional catheterization planning (52%, 14/27). Double outlet right ventricle was the most commonly modelled lesion (70%, 19/27).

Conclusion

3D printing is a new technology that is beneficial in the care of children with CHD. Access to 3D printing varies by geographic location. In pediatric cardiology, 3D models are primarily used for procedural planning for CHD lesions with complex 3D spatial relationships.

Clarifying the anatomy of common arterial trunk: a clinical study of 70 patients

Aims

Anatomic variations in hearts with common arterial trunk are well-known, although there is no large study of living patients. Detailed knowledge of the origins of the pulmonary and coronary arteries is vital for surgical management. We sought to clarify the variations using computed tomography.

Methods and results

We prospectively studied 70 consecutive patients using echocardiography and computed tomography. In 63 (90%) patients, there was aortic dominance, while 7 (10%) had dominance of the pulmonary component. In 27 (43%) patients with aortic dominance, part of the pulmonary segment arose from a truncal valvar sinus. A long confluent pulmonary channel was more common in patients with sinusal origin compared to those with non-sinusal origin of the pulmonary segment (19 vs. 0; P = 0.0005). Close proximity between the orifices of the coronary arteries and the pulmonary component was also more frequent with sinusal origin (21 vs. 6; P < 0.001) with 5 (19%) patients having pulmonary flow obstructed by a truncal valvar leaflet.

Conclusion

Sinusal origin of the pulmonary component is common with aortic dominance, frequently in association with a long confluent pulmonary segment, which may be in close proximity to the origin of a coronary artery. One-fifth of patients with sinusal origin of pulmonary component have a truncal valvar leaflet obstructing the pulmonary orifice. These morpho-anatomic findings have important implications for management.