Assessing the borderline ventricle in a term infant: combining imaging and physiology to establish the right course

Contemporary management of borderline left ventricle

Borderline left ventricle cases present considerable difficulties in determining the most effective surgical approaches. The evolution of approaches in the field has shifted from classical systemic pulmonary shunts to orthodox univentricular palliation and has subsequently seen the emergence of biventricular repair concepts. The concept of biventricular repair for borderline left heart conditions has developed through studies that aim to establish predictive scoring systems for identifying appropriate candidates. Despite continuous efforts, a definitive scoring system for guiding this decision is still difficult to find. There is a growing trend to provide neonatal patients with borderline ventricles with options other than univentricular palliation. Several centres have developed personalized strategies, including hybrid and staged ventricular recruitment approaches. These strategies provide sufficient time for personalized decision-making, taking into account the individual circumstances of each patient. This article presents an overview of the changing approaches to borderline left ventricular cases. It discusses the use of predictive scoring systems and emphasizes the advancements in staged strategies that improve the likelihood of successful biventricular repairs.

Borderline Ventricles: From Evaluation to Treatment

A heart with a borderline ventricle refers to a situation where there is uncertainty about whether the left or right underdeveloped ventricle can effectively support the systemic or pulmonary circulation with appropriate filling pressures and sufficient physiological reserve. Pediatric cardiologists often deal with congenital heart diseases (CHDs) associated with various degrees of hypoplasia of the left or right ventricles. To date, no specific guidelines exist, and surgical management may be extremely variable in different centers and sometimes even in the same center at different times. Thus, the choice between the single-ventricle or biventricular approach is always controversial. The aim of this review is to better define when "small is too small and large is large enough" in order to help clinicians make the decision that could potentially affect the patient's entire life.

Modern advances regarding interatrial communication in congenital heart defects

BACKGROUND

The interatrial communication, one of the most frequent congenital heart defects, represents an important intracardiac shunt between systemic and pulmonary circulations. Direction and magnitude of the interatrial shunting depends upon several features, including defect size, shape and location, pressure difference between right and left atrium, and difference in right and left ventricular compliance.

METHODS

In this review article, the presence or absence of interatrial communication, and its role, have been analyzed, as they can have a critical impact on the cardiovascular physiopathology, and the interatrial communication can prove to be either clinically harmful, useful or indispensable. Accordingly, the utility and role of the interatrial communication in modern congenital, pediatric and adult, disease has evolved, with modification of the indications to close, maintain patency, or create an interatrial communication.

RESULTS

The interatrial communication and shunting can be manipulated to maximize the oxygen delivery to the tissues, accordingly with the underlying congenital heart defect. While not always relevant to patients with bi-ventricular circulations, this becomes extremely important in children and adults with complex congenital heart defects.

CONCLUSIONS

With improving long-term survival for the vast majority of congenital heart patients, an advanced understanding of the role and utility of the interatrial communication, and of all the possibilities of its manipulation, is essential to improve the patient outcomes.

Small and borderline left ventricular outflow tract - a perplexing maladie

The left ventricular outflow tract (LVOT) comprises of the subvalvular area, the aortic valve, and the supravalvular region. Obstructive lesion of LVOT is a spectrum with varying levels and degree of obstruction with or without associated hypoplasia of the left ventricle. Decision-making in small and borderline LVOT can be challenging. Imaging modalities such as echocardiography and magnetic resonance imaging and scores based on imaging aid in the decision making in truly borderline cases. Newer treatment strategies like staged left ventricular rehabilitation and hybrid procedure have come to the fore in the past decade or so. Although these do not address small LVOT per se, they delay the decision-making to a more appropriate age. The goal of management in these cases is to achieve a biventricular repair whenever feasible. Several surgical techniques could be employed to achieve this goal. However, it is important to be cognizant of the fact that an overzealous approach to achieve a biventricular repair might be counterproductive. A univentricular palliation could be a safer alternative; especially considering the possibility of a future transplant candidacy.

Role of echocardiographic scoring systems in predicting successful biventricular versus univentricular palliation in neonates with critical aortic stenosis

BACKGROUND

There are several published echo-derived scores to help predict successful biventricular versus univentricular palliation in neonates with critical aortic stenosis. This study aims to determine whether any published scoring system accurately predicted outcomes in these neonates.

METHODS

Single centre, retrospective cohort study including neonates who underwent aortic valve intervention (surgical valvotomy or balloon valvuloplasty) with the intention of biventricular circulation. Primary outcome was survival with biventricular circulation at hospital discharge. Data from their initial neonatal echocardiogram were used to compute the following scores - Rhodes, CHSS 1, Discriminant, CHSS 2, and 2 V.

RESULTS

Between 01/1999 and 12/2017, 68 neonates underwent aortic valve intervention at a median age of 4 days (range 1-29 days); 35 surgical valvotomy and 33 balloon valvuloplasty. Survival with biventricular circulation was maintained in 60/68 patients at hospital discharge. Of the remaining eight patients, three were converted to univentricular palliation, four died, and one underwent heart transplant prior to discharge. None of the binary score predictions of biventricular versus univentricular (using that score's proposed cut-offs) were significantly associated with the observed outcome in this cohort. A high percentage of those predicted to need univentricular palliation had successful biventricular repair: 89.4% by Rhodes, 79.3% by CHSS 1, 85.2% by Discriminant, and 66.7% by CHSS 2 score. The 2 V best predicted outcome and agreed with the local approach in most cases.

CONCLUSION

This study highlights the limitations of and need for alternative scoring systems/cut-offs for consistently accurate echocardiographic prediction of early outcome in neonates with critical aortic stenosis.

Prediction of biventricular repair by echocardiography in borderline ventricle

Objective:

In recent years, attempting the biventricular pathway or biventricular conversions in patients with borderline ventricle has become a hot topic. However, inappropriate pursuit of biventricular repair in borderline candidates will lead to adverse clinical outcomes. Therefore, it is important to accurately assess the degree of ventricular development before operation and whether it can tolerate biventricular repair. This review evaluated ventricular development using echocardiography for a better prediction of biventricular repair in borderline ventricle.

Data sources:

Articles from January 1, 1990 to April 1, 2019 on biventricular repair in borderline ventricle were accessed from PubMed, using keywords including “borderline ventricle,” “congenital heart disease,” “CHD,” “echocardiography,” and “biventricular repair.”

Study selection:

Original articles and critical reviews relevant to the review's theme were selected.

Results:

Borderline left ventricle (LV): (1) Critical aortic stenosis: the Rhodes score, Congenital Heart Surgeons Society regression equation and another new scoring system was proposed to predict the feasibility of biventricular repair. (2) Aortic arch hypoplasia: the LV size and the diameter of aortic and mitral valve (MV) annulus should be taken into considerations for biventricular repair. (3) Right-dominant unbalanced atrioventricular septal defect (AVSD): atrioventricular valve index (AVVI), left ventricular inflow index (LVII), and right ventricle (RV)/LV inflow angle were the echocardiographic indices for biventricular repair. Borderline RV: (1) pulmonary atresia/intact ventricular septum (PA/IVS): the diameter z-score of tricuspid valve (TV) annulus, ratio of TV to MV diameter, RV inlet length z-score, RV area z-score, RV development index, and RV-TV index, etc. Less objective but more practical description is to classify the RV as tripartite, bipartite, and unipartite. The presence or absence of RV sinusoids, RV dependent coronary circulation, and the degree of tricuspid regurgitation should also be noted. (2) Left-dominant unbalanced AVSD: AVVI, LV, and RV volumes, whether apex forming ventricles were the echocardiographic indices for biventricular repair.

Conclusions:

Although the evaluation of echocardiography cannot guarantee the success of biventricular repair surgery, echocardiography can still provide relatively valuable basis for surgical decision making.