Role of Computed Tomography in Pre- and Postoperative Evaluation of a Double-Outlet Right Ventricle

Pediatric Cardiovascular Computed Tomography: Clinical Indications, Technique, and Standardized Reporting. Recommendations From the Cardiothoracic Taskforce of the European Society of Pediatric Radiology

Congenital heart diseases affect 1% of all live births in the general population. The prognosis of these children is increasingly improving due to advances in medical care and surgical treatment. Imaging is also evolving rapidly to assess accurately complex cardiac anomalies prenatally and postnatally. Transthoracic echocardiography is the gold-standard imaging technique to diagnose and follow-up children with congenital heart disease. Cardiac computed tomography imaging plays a key role in the diagnosis of children with congenital heart defects that require intervention, due to its high temporal and spatial resolution, with low radiation doses. It is challenging for radiologists, not primarily specialized in this field, to perform and interpret these studies due to the difficult anatomy, physiology, and postsurgical changes. Technical challenges consist of necessary electrocardiogram gating and contrast bolus timing to obtain an optimal examination. This article aims to define indications for pediatric cardiac computed tomography, to explain how to perform and report these studies, and to discuss future applications of this technique.

Double outlet right ventricle

This review article addresses the history, morphology, anatomy, medical management, and different surgical options for patients with double outlet right ventricle.

Double outlet ventricles: review of anatomic and imaging characteristics

Hearts with double outlet ventricles and concordant atrioventricular connections account for about 1%–3% of all cases of congenital heart disease. We review hearts with two ventricles and concordant atrioventricular connections with double outlet right ventricle (DORV), double outlet left ventricle (DOLV) and double outlet both ventricles (DOBV) from the morphological and clinical imaging perspectives. These hearts are a heterogeneous group of congenital cardiac malformations with a wide range of pathophysiologies that require an individualised surgical approach based on a precise understanding of the complex cardiovascular anatomy. Owing to their differing temporal, spatial and contrast resolutions, we propose that multimodality imaging provides optimal characterisation of various intracardiac morphological features of double outlet hearts. This approach aids clinical diagnosis for optimising treatment options across these malformations.

Is combined MDCT and echocardiography needed to guarantee accuracy in diagnosis and surgical planning of DORV and associated anomalies?

Background

The term of Double-outlet right ventricle (DORV) is used to describe a spectrum of complex congenital cardiac malformations where anomalies of the ventriculo-arterial alignment are noted where both great arteries (pulmonary artery and aorta) originate completely or predominantly from the right ventricle. The purpose of this study is to evaluate the diagnostic accuracy of electrocardiography (ECG) gated multidetector computed tomography (MDCT) in preoperative assessment of DORV and its associated malformations, providing key anatomic parameters that affect surgical planning.

Results

A total of 50 patients diagnosed by echocardiography with DORV referred from our institute between September 2018 and August 2020 were enrolled. The location of the ventricular septal defect (VSD) to the great vessels and the alignment of the great vessels to each other as well as other associated malformations that affect the surgical planning were assessed by MDCT. The patients were retrospectively classified into subgroups according to the relative positions of the great arteries, the relationship between the great arteries and the VSD, and the presence of associated malformations according to the classification of Society of Thoracic Surgeons database. The diagnostic value of MDCT and transthoracic echocardiography (TTE) in evaluation of associated cardiac malformations apart from double outlet right ventricle was compared in 20 patients, whom surgeries were performed and surgical results were obtained. Fallot type of DORV was the most common clinical type which represented 48% of the patients in which the VSD is committed to the aorta. The second most common clinical type was Taussig–Bing anomaly which represented 30% of the patients and the VSD was seen committed to the pulmonary artery. The atrio-ventricular septal defect (AVSD)/uni-ventricular type represented 16% of the patients in the current study, with pulmonary and systemic venous anomalies, heterotaxy syndrome and situs anomalies were commonly associated. A total of 53 malformations apart from DORV were found in 20 patients whom performed surgical interventions. MDCT detected different vascular and situs anomalies in those patients with 100% sensitivity and 100% positive predictive value compared to 71.4% and 94% respectively in TTE. On the other hand, in our study TTE was superior to MDCT for detection of intracardiac anomalies with 100% sensitivity and 100% accuracy compared to 87.5% and 95% respectively in MDCT.

Conclusions

Our study suggested that ECG gated MDCT serves as a rapid, noninvasive imaging modality with good spatial resolution and provides excellent diagnostic image quality and has satisfactory diagnostic accuracy in the preoperative assessment of DORV. It is superior to echocardiography in providing a comprehensive mapping of the anatomy of complex anomalies especially that of extra-cardiac structures such as aorta, systemic veins, pulmonary veins, and pulmonary arteries. However, it can miss tiny intracardiac malformations. So combining the results of MDCT and echocardiography would be beneficial to guarantee the accuracy of diagnosis of DORV.

3D modeling and printing for complex biventricular repair of double outlet right ventricle

BACKGROUND

Double outlet right ventricle (DORV) describes a group of congenital heart defects where pulmonary artery and aorta originate completely or predominantly from the right ventricle. The individual anatomy of DORV patients varies widely with multiple subtypes classified. Although the majority of morphologies is suitable for biventricular repair (BVR), complex DORV anatomy can render univentricular palliation (UVP) the only option. Thus, patient-specific decision-making is critical for optimal surgical treatment planning. The evolution of image processing and rapid prototyping techniques facilitate the generation of detailed virtual and physical 3D models of the patient-specific anatomy which can support this important decision process within the Heart Team.

MATERILAS AND METHODS

The individual cardiovascular anatomy of nine patients with complex DORV, in whom surgical decision-making was not straightforward, was reconstructed from either computed tomography or magnetic resonance imaging data. 3D reconstructions were used to characterize the morphologic details of DORV, such as size and location of the ventricular septal defect (VSD), atrioventricular valve size, ventricular volumes, relationship between the great arteries and their spatial relation to the VSD, outflow tract obstructions, coronary artery anatomy, etc. Additionally, physical models were generated. Virtual and physical models were used in the preoperative assessment to determine surgical treatment strategy, either BVR vs. UVP.

RESULTS

Median age at operation was 13.2 months (IQR: 9.6-24.0). The DORV transposition subtype was present in six patients, three patients had a DORV-ventricular septal defect subtype. Patient-specific reconstruction was feasible for all patients despite heterogeneous image quality. Complex BVR was feasible in 5/9 patients (55%). Reasons for unsuitability for BVR were AV valve chordae interfering with potential intraventricular baffle creation, ventricular hypoplasia and non-committed VSD morphology. Evaluation in particular of qualitative data from 3D models was considered to support comprehension of complex anatomy.

CONCLUSION

Image-based 3D reconstruction of patient-specific intracardiac anatomy provides valuable additional information supporting decision-making processes and surgical planning in complex cardiac malformations. Further prospective studies are required to fully appreciate the benefits of 3D technology.

Nuclear Imaging in Pediatric Cardiology: Principles and Applications

Nuclear imaging plays a unique role within diagnostic imaging since it focuses on cellular and molecular processes. Using different radiotracers and detection techniques such as the single photon emission scintigraphy or the positron emission tomography, specific parameters can be assessed: myocardial perfusion and viability, pulmonary perfusion, ventricular function, flow and shunt quantification, and detection of inflammatory processes. In pediatric and congenital cardiology, nuclear imaging can add complementary information compared to other imaging modalities such as echocardiography or magnetic resonance imaging. In this state-of-the-art paper, we appraise the different techniques in pediatric nuclear imaging, evaluate their advantages and disadvantages, and discuss the current clinical applications.

Double Outlet Right Ventricle: In-Depth Anatomic Review Using Three-Dimensional Cardiac CT Data

Double outlet right ventricle (DORV) is a relatively common congenital heart disease in which both great arteries are connected completely or predominantly to the morphologic RV. Unlike other congenital heart diseases, DORV demonstrates various anatomic and hemodynamic subtypes, mimicking ventricular septal defect, tetralogy of Fallot, transposition of the great arteries, and functional single ventricle. Because different surgical strategies are applied to different subtypes of DORV with ventricular septal defects, a detailed assessment of intracardiac anatomy should be performed preoperatively. Due to high spatial and contrast resolutions, cardiac CT can provide an accurate characterization of various intracardiac morphologic features of DORV. In this pictorial essay, major anatomic factors affecting surgical decision-making in DORV with ventricular septal defects were comprehensively reviewed using three-dimensional cardiac CT data. In addition, the surgical procedures available for these patients and major postoperative complications are described.