Nomenclature of the functionally univentricular heart

Fetal single ventricle journey to first postnatal procedure: a multicentre UK cohort study

OBJECTIVES

UK single ventricle (SV) palliation outcomes after first postnatal procedure (FPP) are well documented. However, survival determinants from fetal diagnosis to FPP are lacking. To better inform parental-fetal counselling, we examined factors favouring survival at two large UK centres.

DESIGN

Retrospective multicentre cohort study.

SETTING

Two UK congenital cardiac centres: Leeds and Birmingham.

PATIENTS

SV fetal diagnoses from 2015 to 2021.

MAIN OUTCOME MEASURES

Survival from fetal diagnosis with intention to treat (ITT) to birth and then FPP. Maternal, fetal and neonatal risk factors were assessed.

RESULTS

There were 666 fetal SV diagnoses with 414 (62%) ITT. Of ITT, 381 (92%) were live births and 337 (81%) underwent FPP. Survival (ITT) to FPP was notably reduced for severe Ebstein's 14/22 (63.6%), unbalanced atrioventricular septal defect 32/45 (71%), indeterminate SV 3/4 (75%), mitral atresia 8/10 (80%) and hypoplastic left heart syndrome 127/156 (81.4%). Biventricular pathway was undertaken in five (1%). After multivariable adjustment, prenatal risk factors for mortality were increasing maternal age (OR 1.05, 95% CI 1.0 to 1.1), non-white ethnicity (OR 2.6, 95% CI 1.4 to 4.8), extracardiac anomaly (OR 6.34, 95% CI 1.8 to 22.7) and hydrops (OR 7.39, 95% CI 1.2 to 45.1). Postnatally, prematurity was significantly associated with mortality (OR 6.3, 95% CI 2.3 to 16.8).

CONCLUSIONS

Around 20% of ITT fetuses diagnosed with SV will not reach FPP. Risk varies according to the cardiac lesion and is significantly influenced by the presence of an extracardiac anomaly, fetal hydrops, ethnicity, increasing maternal age and gestation at birth. These data highlight the need for fetal preprocedure data to be used in conjunction with procedural outcomes for fetal counselling.

Single-inlet univentricular heart with persistent truncus arteriosus in a Sumatran orangutan (Pongo abelii)

Univentricular heart malformations are rarely described in the veterinary literature. This case report describes a single-inlet univentricular heart with persistent truncus arteriosus as a cause of death of a captive-bred, 2-day-old, female Sumatran orangutan (Pongo abelii), a critically endangered species.

Cohort study of intervened functionally univentricular heart in England and Wales (2000-2018)

Objective

Given the paucity of long-term outcome data for complex congenital heart disease (CHD), we aimed to describe the treatment pathways and survival for patients who started interventions for functionally univentricular heart (FUH) conditions, excluding hypoplastic left heart syndrome.

Methods

We performed a retrospective cohort study using all procedure records from the National Congenital Heart Diseases Audit for children born in 2000–2018. The primary outcome was mortality, ascertained from the Office for National Statistics in 2020.

Results

Of 53 615 patients, 1557 had FUH: 55.9% were boys and 67.4% were of White ethnic groups. The largest diagnostic categories were tricuspid atresia (28.9%), double inlet left ventricle (21.0%) and unbalanced atrioventricular septal defect (AVSD) (15.2%). The ages at staged surgery were: initial palliation 11.5 (IQR 5.5–43.5) days, cavopulmonary shunt 9.2 (IQR 6.0–17.1) months and Fontan 56.2 (IQR 45.5–70.3) months. The median follow-up time was 10.8 (IQR 7.0–14.9) years and the 1, 5 and 10-year survival rates after initial palliation were 83.6% (95% CI 81.7% to 85.4%), 79.4% (95% CI 77.3% to 81.4%) and 77.2% (95% CI 75.0% to 79.2%), respectively. Higher hazards were present for unbalanced AVSD HR 2.75 (95% CI 1.82 to 4.17), atrial isomerism HR 1.75 (95% CI 1.14 to 2.70) and low weight HR 1.65 (95% CI 1.13 to 2.41), critical illness HR 2.30 (95% CI 1.67 to 3.18) or acquired comorbidities HR 2.71 (95% CI 1.82 to 4.04) at initial palliation.

Conclusion

Although treatment pathways for FUH are complex and variable, nearly 8 out of 10 children survived to 10 years. Longer-term analyses of outcome based on diagnosis (rather than procedure) can inform parents, patients and clinicians, driving practice improvements for complex CHD.

New Horizon of Intervention in Congenital Heart Disease: AFR in a Complex Cyanotic Patient

Double-inlet left ventricle (DILV) is the commonest form of the anatomic univentricular heart which has different ventriculoarterial connection; generally, the most prevalent type is DILV with the hypoplastic right ventricle on the left side. The disease is associated with several heart defects, and the treatment method is different based on the anatomy of the heart, but treatment methods are almost always palliative. In this paper, we described one adult patient with DILV and severe left AV (atrioventricular valve) stenosis who is managed with a novel palliative intervention; it means AFR (atrial flow regulator) device implantation for the first time.

Autopsy in adults with congenital heart disease (ACHD)

The adult congenital heart diseases (ACHD) population is exceeding the pediatric congenital heart diseases (CHD) population and is progressively expanding each year, representing more than 90% of patients with CHD. Of these, about 75% have undergone surgical and/or percutaneous intervention for palliation or correction. Autopsy can be a very challenging procedure in ACHD patients. The approach and protocol to be used may vary depending on whether the pathologists are facing native disease without surgical or percutaneous interventions, but with various degrees of cardiac remodeling, or previously palliated or corrected CHD. Moreover, interventions for the same condition have evolved over the last decades, as has perioperative myocardial preservations and postoperative care, with different long-term sequelae depending on the era in which patients were operated on. Careful clinicopathological correlation is, thus, required to assist the pathologist in performing the autopsy and reaching a diagnosis regarding the cause of death. Due to the heterogeneity of the structural abnormalities, and the wide variety of surgical and interventional procedures, there are no standard methods for dissecting the heart at autopsy. In this paper, we describe the most common types of CHDs that a pathologist could encounter at autopsy, including the various types of surgical and percutaneous procedures and major pathological manifestations. We also propose a practical systematic approach to the autopsy of ACHD patients.

Remodeling of the Embryonic Interventricular Communication in Regard to the Description and Classification of Ventricular Septal Defects

Ventricular septal defects are the commonest congenital cardiac malformations. Appropriate knowledge of the steps involved in completion of ventricular septation should provide clues as to the morphology of the different phenotypes. Currently, however, consensus is lacking regarding the components of the developing ventricular septum, and how best to describe the different phenotypes seen in postnatal life. We have reassessed the previous investigations devoted to closure of the embryonic interventricular communication. On this basis, we discuss how studies in the early part of the 20th century correctly identified the steps involved in the remodeling of the embryonic interventricular foramen subsequent to the stage at which the outflow tract arises entirely above the cavity of the developing right ventricle. There has, however, already been remodeling of the foramen from the stage at which the atrioventricular canal is supported exclusively by the developing left ventricle. We show how these temporal changes in morphology can provide explanations for the different ventricular septal defects seen in the clinical setting. Thus, muscular defects represent inappropriate coalescence of muscular ventricular septum. The channels that are perimembranous are due to failure of closure of the persisting embryonic interventricular foramen. Those that are doubly committed and juxta-arterial reflect failure of formation of the free-standing subpulmonary muscular infundibular sleeve. The findings also point to the importance of appropriate alignment, during development, between the developing atrial and ventricular septums, and between the apical component of the ventricular septum and the ventricular outlet components. Anat Rec, 302:19-31, 2019. © 2018 Wiley Periodicals, Inc.

Anatomy of the Functionally Univentricular Heart

The world of pediatric cardiac surgery and cardiac surgery as a whole lost one of the great pioneers with the passing, at the beginning of 2018, of Francis Fontan. Hence to add to the recognition of his achievements, the European Congenital Heart Surgeons Association (ECHSA) has established a lecture to be given in his memory at their annual meetings. It was a significant honor and privilege to be invited to present the initial lecture. In this report, we describe the essence of the presentation. Many patients are now palliated by construction of the Fontan circulation. Very few of those put forward for this operative procedure have anatomically univentricular hearts. It remains frequent, nonetheless, to find accounts of many patients allegedly having "single" ventricles. We discuss the background to this illogical approach to description of hearts having one big and one small ventricle, showing that those with normal hearts have a single left ventricle, albeit co-existing with a single right ventricle. We show that analysis of the ventricular mass in tripartite fashion produces much needed clarity in the appropriate description of the ventricular mass in those increasingly submitted for construction of the Fontan circulation. We emphasize that although it was patients with univentricular atrioventricular connections who were the first to benefit from the procedure, the majority of patients now have biventricular atrioventricular connections, although the hypoplastic ventricle possesses all three of its normal components. We show that description of the ventricular arrangement as being functionally, or physiologically, univentricular provides logic in what had previously been an illogical environment.

How should we diagnose and differentiate hearts with double-outlet right ventricle?

Many, if not most, of the controversies regarding the description of the congenitally malformed heart have been resolved over the turn of the 20th century. A group of lesions that remains contentious is the situation in which both arterial trunks, in their greater part, are supported by the morphologically right ventricle. It was considered, for many years, that presence of bilateral infundibulums, or conuses, was a necessity for such a diagnosis. It has now been appreciated that this suggestion founders on many counts. In the first instance, such bilateral infundibulums are to be found in patients with other ventriculo-arterial connections, including the otherwise normal heart. In the second instance, it is clear that such an approach abrogates the important principle now known as the morphological method. This states that entities should be defined in terms of their intrinsic morphology and not on the basis of other variable features. It is now also clear that, when assessed simply on the basis of the ventricular origin of the arterial trunks, a significant number of patients fulfil the criteria for so-called "200%" origin of the trunks from the right ventricle when there is fibrous continuity between the leaflets of the atrioventricular and arterial valves. In this review, we show how attention to the morphology of the channel between the ventricles now provides the key to accurately diagnose the ventriculo-arterial connection in patients with suspected double-outlet right ventricle. This is because, when both arterial trunks arise exclusively or predominantly from the morphologically right ventricle, the outlet septum, of necessity, is itself a right ventricular structure. The channel between the ventricles, therefore, is roofed by the inner heart curvature, whether that structure is fibrous or muscular. Our observations then confirm that it is the attachment of the outlet septum, which itself can be muscular or fibrous, which determines the commitment of the interventricular communication to the subarterial outlets. The interventricular communication itself, when directly committed to the ventricular outlets, opens between the limbs of the septomarginal trabeculation or septal band. The defect is subaortic when the outlet septum is attached to the cranial limb of the trabeculation, subpulmonary when attached to the caudal limb, and doubly committed when attached to the inner heart curvature in the roof of the defect. Non-committed defects are no longer positioned within the limbs of the septomarginal trabeculation. Although readily demonstrable by a skilled echocardiographer, we show how these anatomical features are more easily demonstrated with added accuracy when using CT data sets.

The new concept of univentricular heart

The concept of univentricular heart moved from hearts with only one ventricle connected with atria [double inlet ventricle or absent atrioventricular (AV) connection] to hearts not amenable to biventricular repair, namely hearts with two ventricles unable to sustain separately pulmonary and systemic circulations in sequence. In the latter definition, even hearts with one hypoplastic ventricle are considered "functional" univentricular hearts. They include pulmonary/aortic atresia or severe stenosis with hypoplastic ventricle, and rare conditions like huge intramural cardiac tumors and Ebstein anomaly with extreme atrialization of right ventricular cavity. In this setting, the surgical repair is univentricular with "Fontan" operation, bypassing the ventricular mass. In other words, functionally univentricular heart is a condition in which, after surgery, only one ventricle sustain systemic circulation. Univentricular hearts (double inlet or absent AV connection) almost invariably show two ventricular chambers, one main and one accessory, which lacks an inlet portion. The latter is located posteriorly when morphologically left and anteriorly when morphologically right. As far as double inlet left ventricle, this is usually associated with discordant ventriculo-arterial (VA) connection (transposition of the great arteries) and all the blood flow to the aorta, which takes origin from the hypoplastic anterior right ventricle, is ventricular septal defect (bulbo-ventricular foramen) dependent. If restrictive, an aortic arch obstruction may be present. Double inlet left ventricle may be rarely associated with VA concordance (Holmes heart). As far as double inlet right ventricle with posterior hypoplastic left ventricular cavity, ventriculo-arterial connection is usually of double outlet type; thus the term double inlet-outlet right ventricle may be coined. Absent right or left AV connection may develop in the setting of both d- or l-loop, whatever the situs. In this condition, the contra-lateral patent AV valve may be either mitral or tricuspid in terms of morphology and the underlying ventricle (main chamber) either morphologically left or right. Establishing the loop, whatever right or left (also called right or left ventricular topology), is a fundamental step in the segmental-sequential analysis of congenital heart disease.

Methodological review of ventricular anatomy--the basis for understanding congenital cardiac malformations

The ventricular mass extends from the atrioventricular to the ventriculo-arterial junctions. The junctions are obvious anatomic entities and provide discrete boundaries for the ventricles, which can then be subdivided into inlet, apical, and outlet components. The apical trabecular components are most constantly present when hearts are congenitally malformed. Abnormal ventricles, such as found in such congenitally malformed hearts, can be analysed according to the way in which the inlet and outlet components are shared between these apical components. The interrelationships of the right and left ventricles permit distinction of two specific patterns, which are mirror images of one another and which can be described in terms of right-handed and left-handed ventricular topology. It is exceedingly rare to find truly solitary ventricles. The conduction tissues are the only parts of the ventricular walls that are insulated within the working myocardial mass. Anomalous accessory muscular connections are the substrate for the Wolff-Parkinson-White syndrome. This article is part of a JCTR special issue on Cardiac Anatomy.

Anatomy of Functionally Single Ventricle

Hearts that have previously been called univentricular hearts, or single ventricles, can be described as having a univentricular atrioventricular connection. Most such hearts have two ventricular chambers, albeit one is small and incomplete—lacking an inlet component. The atriums of these hearts connect only to one of these ventricular chambers, which is usually the larger and dominant ventricle. Other hearts, with biventricular atrioventricular connections, may have hypoplasia of one ventricle, making it impossible to restore a biventricular circulation and such hearts are functionally univentricular. The term “functionally single ventricle” (or functionally univentricular heart) encompasses both these categories of malformation.

What is a ventricle?

On the basis of both developmental and morphological evidence, we would suggest that a ventricle is best defined as any chamber within the ventricular mass possessing an apical trabecular component. Such ventricles can be of right or left morphology, and always coexist. The ventricles are normally formed when possessing all three of the inlet, apical trabecular, and outlet components, but incomplete when lacking one or both of the inlet and outlet components. Ventricles that are incomplete because of lack of the inlet component are always hypoplastic, with incomplete right ventricles being positioned antero-superiorly within the ventricular mass, and incomplete left ventricles located postero-inferiorly. Patients having such incomplete ventricles because of the lack of the inlet component have functionally univentricular hearts, although the functionally univentricular arrangement can also be produced in the setting of normally constituted but hypertrophied ventricles. Full analysis of ventricular morphology, therefore, requires attention not only to component make-up, but also size.

Report from The International Society for Nomenclature of Paediatric and Congenital Heart Disease: cardiovascular catheterisation for congenital and paediatric cardiac disease (Part 1 - Procedural nomenclature)

Interventional cardiology for paediatric and congenital cardiac disease is a relatively young and rapidly evolving field. As the profession begins to establish multi-institutional databases, a universal system of nomenclature is necessary for the field of interventional cardiology for paediatric and congenital cardiac disease. The purpose of this paper is to present the results of the efforts of The International Society for Nomenclature of Paediatric and Congenital Heart Disease to establish a system of nomenclature for cardiovascular catheterisation for congenital and paediatric cardiac disease, focusing both on procedural nomenclature and on the nomenclature of complications associated with interventional cardiology. This system of nomenclature for cardiovascular catheterisation for congenital and paediatric cardiac disease is a component of The International Paediatric and Congenital Cardiac Code. This manuscript is the first part of a two-part series. Part 1 will cover the procedural nomenclature associated with interventional cardiology as treatment for paediatric and congenital cardiac disease. This procedural nomenclature of The International Paediatric and Congenital Cardiac Code will be used in the IMPACT Registry™ (IMproving Pediatric and Adult Congenital Treatment) of the National Cardiovascular Data Registry® of The American College of Cardiology. Part 2 will cover the nomenclature of complications associated with interventional cardiology as treatment for paediatric and congenital cardiac disease.

Anatomical and pathophysiological classification of congenital heart disease

Congenital heart diseases (CHD) consist of defects of the cardiac architecture which interfere with the venous drainage, septation of the cardiac segments and their sequences and regular function of the valve apparatuses. In the normal heart the segments are disposed in such a way to allow deoxygenated venous blood to go to the lungs through the pulmonary artery and the oxygenated venous blood to go to the systemic organs through the aorta without mixing. Small and great circulations are in sequence, with no communication to each other. Establishing the sequence of cardiac segments is the prerequisite for planning a surgical repair. We propose a pathyphysiological classification of CHD based upon the clinical consequence of structural defects on the physiology of blood circulation. We divided cardiac anomalies in: (1) CHD with increased pulmonary blood flow (septal defects without pulmonary obstruction and with left-to-right shunt); (2) CHD with decreased pulmonary flow (septal defects with pulmonary obstruction and with right-to-left shunt); (3) CHD with obstruction to blood progression and no septal defects (no shunt); (4) CHD so severe as to be incompatible with postnatal blood circulation; and (5) CHD silent until adult age.

The development and structure of the ventricles in the human heart

Over the past decade, much has been learned concerning the origin and development of the ventricles. However, most, if not all, of the new information has come from study of the mouse heart. Most of this information has yet to be assimilated by those who study ventricular function or diagnose congenitally malformed hearts. Nevertheless, the evidence available from recent studies, particularly if it can be shown relevant to human development, is remarkably pertinent to these topics. For example, knowledge of how each ventricle derives its inlet and outlet components, information available for human development (Lamers et al., Circulation 86:1194-1205, 1992), provides a firm foundation for understanding congenital cardiac malformations, particularly those dependent on a functionally univentricular circulation (Jacobs and Anderson, Cardiol Young 16(Suppl 1):3-8, 2006). Appreciation of ventricle development also is important with regard to understanding the basis of so-called ventricular noncompaction because this knowledge will elucidate whether the compact component of the ventricular walls is produced by consolidation of the initially extensive trabecular zone seen during early development or by defective formation and/or maturation of the compact myocardium (Anderson, Eur Heart J 29:10-11, 2008). Knowledge concerning the mechanism whereby ventricular myocytes are packed within the compact component of the ventricular walls then will help clarify the architectural arrangement of the aggregated myocytes, a topic of considerable recent interest. This review discusses all these topics.

One hundred years of texts describing congenitally malformed hearts from 1814 to 1914

Before paediatric cardiology emerged as a specialty in the mid 20th century, a body of literature had developed over centuries devoted to description of congenitally malformed hearts. In this review, we have selected highlights from such texts written during the period of 100 years from 1814 to 1914, demonstrating their potential relevance to controversies occurring during the twentieth century in the categorisation of such hearts. We begin in 1814, with the first wide-ranging book devoted to congenital cardiac malformations. We end with a publication from 1914, because it included an illustration of the first electrocardiogram in a text devoted to paediatric disease. As we will show, these works from the 19th and early 20th centuries reflect topics still relevant today, namely the aetiology of cardiac malformations, clinicopathologic correlations, attempts at classification, and lack of effective treatments. Attention to their content could have served to ameliorate controversies, some of them ongoing.

Morphologic features of the uniatrial but biventricular atrioventricular connection

OBJECTIVES

Hearts with an absent atrioventricular connection and a straddling of the solitary atrioventricular valve are rare but significant lesions. They are suitable only for Fontan-like palliation, in which atrioventricular valvar abnormalities play a significant role in determining the outcome. We studied the segmental arrangements in such lesions and clarified the valvar morphology, particularly its surgical implications.

METHODS

We made a macroscopic review of all specimens with an absent atrioventricular connection and a straddling atrioventricular valve that were held in the collections of 3 institutes. We included only those specimens with the straddling valve supported exclusively by either the right-sided or left-sided atrioventricular junction and excluded those with a common atrioventricular junction.

RESULTS

We found 11 hearts with an absent right atrioventricular connection and a straddling left atrioventricular valve, and 3 with an absent left atrioventricular connection and a straddling right atrioventricular valve. Most had right-hand ventricular topology and discordant ventriculoarterial connections. We found multiple valvar abnormalities, including dysplastic leaflets, short cords, abnormal attachments, and abnormal papillary muscles. The most consistent features were a line of maximal coaptation between the bridging leaflets always perpendicular to the plane of the ventricular septum and a free-floating bridging anterosuperior leaflet.

CONCLUSIONS

Straddling of a solitary atrioventricular valve with an absent atrioventricular connection produces a uniatrial but biventricular connection. In this setting, the valve guarding the abnormal solitary atrioventricular junction cannot be classified morphologically as mitral or tricuspid. The markedly variable valvar morphology likely makes these valves prone to insufficiency in the long term.

The anatomy of hearts with double inlet ventricle

In the past, hearts with double inlet ventricle have been amongst the most contentious of congenital cardiac malformations. This is because, although most examples found with this particular atrioventricular connection have one big and one small chamber within the ventricular mass, for many years the variant most frequently encountered, with a dominant left ventricle, was usually described as exhibiting a single ventricle.1With the recognition that, in this particular variant, the small chamber is an incomplete right ventricle, and is never capable of supporting independently the pulmonary circulation, the anatomic situation has now been clarified, as explained in the previous review,2by recognising that the arrangement produces a functionally single ventricle, and that almost always patients with this lesion, if treated surgically, will be converted to the Fontan circulation. Even though, nonetheless, most patients with all variants of double inlet ventricle will likely end up with the Fontan circulation, it remains necessary to identify the functionally significant variants, namely those to be found in ventricular morphology, atrioventricular valvar morphology, ventriculo-arterial connections, and associated malformations.3

Classification of the functionally univentricular heart: unity from mapped codes

The nomenclature and classification of patients with a functionally univentricular heart has been debated for decades. We review here the approach taken for dealing with this group of patients by the International Working Group for Mapping and Coding of Nomenclatures for Paediatric and Congenital Cardiac Disease. We discuss the approach of this Nomenclature Working Group in the context of other historical and contemporary ideas about this topic.

Echo-morphological correlates in atrioventricular valvar atresia

As we described in the previous review,1 double inlet ventricle is usually found with the atrial chambers connected to a dominant left ventricle, less frequently to a dominant right ventricle, and rarely to a solitary and indeterminate ventricle. As we have also discussed in this supplement,2 double inlet to the left ventricle was, for many years, considered the exemplar of so-called “single ventricle”, despite the fact that such patients unequivocally possess one big and one small ventricle. Echocardiographic interrogation has served to resolve this controversy, showing that such patients make up a significant proportion of those having functionally univentricular hearts. Such echocardiographic investigation has also served to resolve similar controversies regarding patients having tricuspid atresia. For some time, it was argued that patients with tricuspid atresia also had “univentricular hearts”,3 but the logic used to underscore this approach was just as flawed as that used to justify the use of “single ventricle” in patients with double inlet atrioventricular connection.4,5 The increasing use of the Fontan procedure has served to demonstrate that these patients, along with many having mitral atresia in the setting of hypoplastic left heart syndrome, also have functionally univentricular arrangements. As we will show in this review, however, the anatomical substrates found in patients with atrioventricular valvar atresia are much more complex than those seen in the setting of double inlet ventricle. This is because atrioventricular valvar atresia can be produced either by absence of one atrioventricular connection, or by presence of an imperforate valvar membranes closing completely one or other of the two normal atrioventricular junctions. This important difference, combined with multiple segmental combinations, produces a bewildering array of potential anatomical substrates, with the complications magnified by the fact that, when one atrioventricular connection is absent, the other atrioventricular junction can be shared between the two ventricles, the so-called uniatrial and biventricular arrangement.6 In our review, we will first describe the anatomical options, before concentrating our attention on the more frequent patterns seen in clinical practice.