Preoperative Physiology, Imaging, and Management of Transposition of the Great Arteries

Impact of Bedside Balloon Atrial Septostomy in Neonates with Transposition of the Great Arteries in a Neonatal Intensive Care Unit in Romania

(1) Background: Transposition of the great arteries (TGA) is the most common congenital heart disease, accounting for 5-7% of all cardiac anomalies, with a prevalence of 0.2-0.3 per 1000 live births. (2) Aim: Our main objectives were to evaluate the clinical safety of balloon atrial septostomy in neonates and the possible complications. Furthermore, we tried to establish whether the procedure should be performed in all TGA patients with small atrial septal defects, regardless of oxygen saturation, within a center where corrective surgery cannot be performed on an emergency basis due to the lack of a permanent cardiac surgery team for arterial switch surgery. (2) Methods: We conducted an observational, retrospective, single tertiary-care center study between January 2008 and April 2022, which included 92 neonates with TGA transferred to our institution for specialized treatment. (3) Results: The median age at the time of the Rashkind procedure was four days. The rate of immediate complications after balloon atrial septostomy (BAS) was high (34.3%), but most were transient (metabolic acidosis and arterial hypotension-21.8%). Twenty patients with TGA managed in our hospital underwent definitive and corrective surgical intervention (arterial switch operation) at a median age of 13 days. Most patients (82.6%) were term neonates, but 16 were born preterm. (4) Conclusions: Urgent balloon atrial septostomy is often the only solution to restore adequate systemic perfusion. Bedside balloon atrial septostomy is a safe, effective, and initial palliative intervention in neonates with TGA, which can be performed in the neonatal unit.

Management of the Adult with Arterial Switch

Dextro-transposition of the great arteries (d-TGA) is a lethal congenital heart defect in which the great arteries-the pulmonary artery and aorta-are transposed to create ventriculoarterial discordance. Corrective surgical interventions have resulted in significant improvements in morbidity and mortality for this once-fatal congenital heart defect. The initial palliative surgery for d-TGA was the atrial switch operation, which provided physiological correction. The Mustard and Senning "atrial switch" procedures, in which an atrial baffle is created to produce a discordant atrioventricular connection on the existing discordant ventriculoarterial connection, showed preliminary success for the correction of d-TGA. However, follow-up evaluations demonstrated increasing complications from the right ventricle utilized as a systemic ventricle, resulting in progressive right ventricular dysfunction. Thus, the search continued for an anatomical correction of d-TGA to return the great arteries to their normal ventricular connections. The arterial switch operation (ASO), though attempted and theorized by many, was first successfully performed by Dr. Jatene and colleagues in 1975. For ASO, the distal main pulmonary artery and the distal ascending aorta are transected and then anastomosed to their respective ventricles with relocation of the coronary arteries to the neoaorta. The ASO has replaced the atrial switch operation since the 1980s and is now the standard surgical correction for d-TGA. As more patients who have undergone ASO are living into adulthood, late complications of this procedure have become more evident. The most common late postoperative complications include coronary artery stenosis, neoaortic root dilation, neoaortic insufficiency, and neopulmonic stenosis. Adults who have undergone ASO in childhood will need follow-up with surveillance imaging and evaluation of new symptoms or declining function to prevent and manage late postoperative complications. This review describes the management strategies for common late complications in patients who have undergone ASO.

3D modeling: a future of cardiovascular medicine

Cardiovascular disease resulting from atypical cardiac structures continues to be a leading health concern despite advancements in diagnostic imaging and surgical techniques. However, the ability to visualize spatial relationships using current technologies remains a challenge. Therefore, 3D modeling has gained significant interest to understand complex and atypical cardiovascular disorders. Moreover, 3D modeling can be personalized and patient-specific. 3D models have been demonstrated to aid surgical planning and simulation, enhance communication among surgeons and patients, optimize medical device design, and can be used as a potential teaching tool in medical schools. In this review, we discuss the key components needed to generate cardiac 3D models. We highlight prevalent structural conditions that have utilized 3D modeling in pre-operative planning. Furthermore, we discuss the current limitations of routine use of 3D models in the clinic as well as future directions for utilization of this technology in the cardiovascular field.

Explanatory models in neonatal intensive care: a tutorial

Background

Acute care providers intervening on fragile patients face many knowledge and information related challenges. Explanation based on causal chains of events has limitations when applied to complex physiological systems, and model-driven educational software may overwhelm the learner with information. We introduce a new concept and educational technology to facilitate understanding, reasoning, and communication in the clinical environment. The aim is to grasp complex physiology in a more intuitive way.

Explanatory models (EM)

An EM is a representation of relevant physiologic processes that provides insight into the relationships between therapeutic interventions and monitored variables, and their dependency on incidents and pathologies. We systematically analyze types of information incorporated into models and displayed in simulations and consider their explanatory relevance.

Transposition of the great arteries (TGA)

A conceptual model (diagram) of the normal neonatal cardiorespiratory system is adapted to reflect TGA and implemented in animated, interactive software.

Illustration of educational use

The use of this model is illustrated via the explanation to pediatric residents of the relationships between blood pressures, blood flow rates, ventilation, oxygen saturation, and oxygen distribution in a neonate with TGA. Learners explore clinical scenarios and effects of therapeutic interventions.

Discussion

Explanatory models hold promise as mental models for clinical practice and could possibly play a role in clinical decision making in neonatal intensive care and beyond.

Companion software

The software is freely available via the web addendum: https://www.dropbox.com/sh/ciufq5rqxgs9bkt/AAC7oKsvkEr73eYUJkx0pZ1Ya?dl=0

Anomalous Origin of the Right Subclavian Artery in a Patient with D-transposition of the Great Arteries

This case report concerns a young patient with an extremely rare combination of d-transposition of the great arteries (d-TGA) and anomalous origin of the right subclavian artery. In our patient, the right subclavian artery originated from the pulmonary artery, which is why he did not show reversed differential cyanosis. We conclude that the presence of an aortic arch anomaly should be considered in patients with d-TGA who do not present with reversed differential cyanosis. A further imaging work-up, including computed tomography or magnetic resonance imaging, might be helpful.

Assessment of transposition of the great arteries associated with multiple malformations using dual-source computed tomography

Purpose

To determine the value of dual-source computed tomography (DSCT) in depicting the morphological characteristics and diagnosing the associated malformations for patients with transposition of the great arteries (TGA) before surgery.

Materials and methods

Twenty-five patients with TGA who underwent DSCT and transthoracic echocardiography (TTE) examination were retrospectively reviewed. The morphological types of TGA, the spatial relationship between the pulmonary artery and the aorta, as well as coronary artery-associated abnormalities were assessed by DSCT. In contrast to TTE, the diagnostic accuracy of associated malformations on DSCT were analyzed and calculated with reference to surgical or digital subtraction angiography (DSA) findings. Effective doses (EDs) were also calculated.

Results

Among the 25 patients, 12 (48%) had ventricular septal defects and left ventricular outflow tract stenosis. Sixteen patients (16/25, 64%) had great arteries with an oblique spatial relationship on DSCT. In addition, we found seven patients (7/25, 28%) with coronary artery malformation, including five with an abnormal coronary origin and two with signs of a myocardial bridge. According to DSA or surgical findings, DSCT was superior to TTE in demonstrating extracardiac anomalies (sensitivity, anomalies of great vessels: 100% vs. 93.33%, other anomalies: 100% vs. 46.15%). The mean estimated ED for those aged <10 years was <2 mSv (1.59 ± 0.95 mSv).

Conclusions

DSCT can achieve an overall assessment of patients with TGA, including any associated malformations as well as the identification of the spatial relationship of the great arteries. DSCT can therefore be considered as an alternative imaging modality for surgical decision making.

Noteworthy Literature in 2015

This article is a review of the literature published during the 12 months of 2015, which is of interest to the congenital cardiac anesthesiologist. While the review is not exhaustive, it identifies 7 themes in the literature for 2015 and cites 78 peer-reviewed publications.