| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Ann Thorac Surg 2000;69:S197-S204
© 2000 The Society of Thoracic Surgeons
a Section of Cardiothoracic Surgery, St. Christopher’s Hospital for Children, Philadelphia, Pennsylvania, USA
b Department of Cardiac Surgery, Children’s Hospital, Boston, Massachusetts, USA
Address reprint requests to Dr Jacobs, Section of Cardiothoracic Surgery, St. Christopher’s Hospital for Children, Erie Ave at Front St, Philadelphia, PA 19134-1095
Presented at the International Nomenclature and Database Conferences for Pediatric Cardiac Surgery, 1998–1999.
Abstract
The extant nomenclature for single ventricle (SV) hearts is reviewed for the purpose of establishing a unified reporting system. The subject was debated and reviewed by members of the STS-Congenital Heart Surgery Database Committee and representatives from the European Association for Cardiothoracic Surgery. Efforts were made to include all relevant nomenclature categories using synonyms where appropriate. Although many issues regarding single ventricle or univentricular hearts remain unresolved among anatomists and pathologists, a classification is proposed that is relevant to surgical therapy. A comprehensive database set is presented, which is based on a hierarchical scheme. Data are entered at various levels of complexity and detail, which can be determined by the clinician. These data can lay the foundation for comprehensive risk stratification analyses. A minimum data set is also presented that will allow for data sharing and would lend itself to basic interpretation of trends. Outcome tables relating diagnoses, procedures, and various risk factors are presented.
I. Background
Among the most challenging of congenital heart malformations are the broad category of hearts that lack two well-developed ventricles. As challenging as they are to manage, medically and surgically, they are at least as difficult to describe and classify. Even the most commonly used terms, single ventricle and univentricular heart, spark heated debate, and can at times be misleading. Only rarely do hearts truly possess a solitary ventricle. As opposed to the common circumstance where there are two atria, and each atrium is connected to its own ventricle, the hearts considered in this section are those in which the atrial chambers connect to only one ventricle that is well developed and dominant. A well-developed ventricle is characterized by an inlet portion, supporting the subvalvar tensor apparatus, a trabecular zone, and an outlet portion to a great artery. Often, there is in addition an incomplete, rudimentary, or hypoplastic ventricle that lacks an atrioventricular connection. The physiologic result is that the systemic and pulmonary circulations are arranged in parallel fashion, rather than in series as in the normal heart. This results in a drastically altered natural history, which without surgical intervention, culminates in death of the patient anywhere from the first days of life to the second decade of life. The evolution of palliative and reconstructive cardiac operations has had an enormous impact on the life expectancy and quality of life of such individuals. It has therefore become increasingly important to be precise and thorough in the description and classification of single ventricle anomalies. For purposes of this discussion, we will consider single ventricle anomalies to be those cardiac malformations that are characterized by the lack of two completely well developed ventricles. This is in contradistinction to some cardiac anomalies where even in the presence of two well-developed ventricles the heart may be considered nonseptatable and thus lend itself to similar treatment strategies to those which are applied to single ventricle hearts.
GUEST EDITORS’ NOTE: Personal communication with Professor Robert Anderson at the 13th Annual Meeting of The European Association for Cardiothoracic Surgery, Glasgow, Scotland, September 5–8, 1999 reveals that Professor Anderson prefers the term, functionally single ventricle rather than the term, single ventricle because these hearts generally have a functional single ventricle in addition to a diminutive or hypoplastic ventricle. We agree that the hearts that we classify as single ventricle in reality have a single well-developed ventricle and may also have an additional incomplete, rudimentary, or hypoplastic ventricle. Thus, our concept of single ventricle is consistent with Professor Anderson’s concept of functionally single ventricle. Our reluctance to use the term functionally single ventricle in this database scheme stems from the popular use of the term single ventricle in the surgical literature. As these initiatives progress, more debate by surgeons, anatomists, and pediatric cardiologists may result in nomenclature changes that will keep these initiatives as works in progress with the eventual goal of establishing a uniform nomenclature system across geographic boundaries and specialty preferences.
Although successful septation of a univentricular heart was accomplished at the Mayo Clinic as long ago as 1957 [1], most efforts at surgical treatment of single ventricle hearts were palliative until Fontan and Baudet [2] and Kreutzer and colleagues [3] independently, but contemporaneously managed patients with tricuspid atresia by diverting the systemic venous return directly from the caval veins and right atrium to the pulmonary arteries. Palliative procedures that in an earlier era were undertaken primarily to compensate for adverse imbalances between systemic and pulmonary blood flow, now have a more carefully considered role in a staged surgical approach that is intended to culminate with a Fontan-type procedure, and that depends for its success upon preservation of optimal function of the systemic ventricle and of the pulmonary vasculature. In the current era, definitive procedures, which are performed to ultimately separate the systemic and pulmonary circulations, are most often referred to as modified Fontan procedures, and less often as total caval pulmonary connections, though the actual forms that these operations take, bear little resemblance to the procedures performed by Professor Fontan three decades ago. Likewise, in the current era, septation of hearts with only one well developed ventricle remains in the armamentarium of the congenital heart surgeon, but is rarely undertaken.
It has become clear over time that the principle determinants of success of a Fontan-type operation or total caval pulmonary connection as definitive therapy for a heart lacking two well-developed ventricles are: (1) optimal systolic and diastolic function of the systemic ventricle, and (2) unobstructed pathways with minimal impedance to flow from the systemic veins, through the pulmonary vasculature, and ultimately back to the systemic ventricle. Numerous anatomic details, and their physiologic consequences, have come to be recognized as incremental risk factors for suboptimal outcomes. Therefore, it is important for a system of nomenclature that describes single ventricle anomalies to address as many anatomic details as possible, without becoming so cumbersome as to compromise utility.
II. Analysis: a unified nomenclature system
Among pathologists and cardiac anatomists, the debate as to what truly constitutes a single ventricle or a univentricular heart, raged long before the era of surgical therapy for these complicated cardiac anomalies. The debate continues today, and no single system of nomenclature has as yet been accepted by all practitioners in the field. There is no escaping the fact that for those of us who treat patients with such anomalies, it is absolutely necessary that we be able to communicate using a nomenclature made up of precise, and preferably simple terminology.
Historically, the terms single ventricle and common ventricle were employed interchangeably by Abbott [4], Taussig [5], and Edwards [6]. Lev [7] used the designation single ventricle when an outlet chamber was present, and the term common ventricle when an outlet chamber was absent. When an outlet chamber is present, the connection between the main ventricular chamber and the outlet chamber has been given a variety of names, including ventricular septal defect, bulboventricular foramen, outlet foramen, trabecular septal defect, and interventricular communication. Currently, most single ventricle anomalies are generally described either using Van Praagh’s segmental anatomy approach [8] or Anderson’s system of sequential chamber localization [9]. According to Van Praagh [10], a single or common ventricle is one ventricular chamber that receives both the tricuspid and mitral valves, or a common atrioventricular valve. Thus, this definition excludes tricuspid and mitral atresia. Anderson’s system likewise emphasizes the nature of the connections between the atrial and ventricular structures, asserting that the unifying criterion for univentricular hearts is that the entire atrioventricular junction is connected to only one chamber in the ventricular mass. A second ventricular chamber, if present, will lack any atrioventricular connection, and hence be rudimentary. Thus one system of classification and definition excludes tricuspid atresia and mitral atresia, requiring a separate system of classification for these anomalies. The other system makes the distinction between hearts with a double inlet ventricle, and hearts with absence of an atrioventricular connection, but acknowledges that because a heart with absence of one atrioventricular connection is a univentricular heart, then tricuspid atresia is among those anomalies associated with a univentricular heart. Obviously, the scholars who pursue this controversy have justifiable reasons for doing so, related primarily to furthering the understanding of normal and abnormal cardiac development. But in developing a uniform reporting system of utility to clinicians, we have pursued the goals of universality and relative simplicity, and have therefore adopted a descriptive language that incorporates some elements of both the segmental classification and the sequential chamber localization approach, and combines these with other familiar systems of classification as for example that which has evolved with respect to tricuspid atresia [11].
The consensus of the STS-Congenital Heart Surgery Database Committee and representatives from the European Association for Cardiothoracic Surgery was that the nomenclature proposal for single ventricle hearts would encompass hearts with double inlet atrioventricular connection (both double inlet left ventricle (DILV) and double inlet right ventricle (DIRV)), hearts with absence of one atrioventricular connection (mitral atresia and tricuspid atresia), hearts with a common atrioventricular valve and only one completely well-developed ventricle (unbalanced common atrioventricular canal defect), hearts with only one fully well-developed ventricle and heterotaxia syndrome (single ventricle heterotaxia syndrome), and finally other rare forms of univentricular hearts that do not fit in one of the specified major categories. Despite the recognition that hypoplastic left heart syndrome is a common form of univentricular heart, with a single or dominant ventricle of right ventricular morphology, the current nomenclature and database proposal includes an entirely separate section for consideration of hypoplastic left heart syndrome. Also, it is recognized that a considerable variety of other structural cardiac malformations, such as pulmonary atresia with intact ventricular septum, biventricular hearts with straddling atrioventricular valves, and some complex forms of double outlet right ventricle (DORV), may at times be best managed in a fashion similar to that which is used to treat univentricular hearts. Nomenclature for description of those entities, however, is not included in this section.
Recommendations for hierarchical order and definitions
Acknowledging the lack of two well-developed ventricles, one must then decide that the dominant ventricle has features of either a left or right ventricle. This distinction is made based on morphology of the ventricle and not on position. Left ventricles have relatively smooth internal walls and lack chordal attachments of the atrioventricular valves to the rudimentary septal surface. Right ventricles are more heavily trabeculated, and generally have chordal attachments of the atrioventricular valve to the septal surface. In addition to those single ventricle hearts with an identifiable dominant ventricle of either left ventricular or right ventricular morphology, are some few with a primitive or indeterminate type of ventricular mass. Additionally, each class of single ventricle heart may have associated abnormalities of atriovisceral situs, of one or both atrioventricular valves, of one or both semilunar valves, and of the relations (transposition or malposition) of the great arteries.
In general the surgical management of hearts with single ventricle anatomy involves a combination strategy based upon palliative and physiologically corrective procedures. Palliative procedures are those that address an imbalance between pulmonary and systemic blood flow, without separating the pulmonary and systemic circulations (see "Congenital Heart Surgery Nomenclature and Database Project: Palliative Repair or Correction" by Cassandra Joffs and Robert M. Sade, this issue). Physiologically corrective procedures are those that are designed to completely separate the pulmonary and systemic circulations (creating in series circulations), achieving the goals of normal volume work for the systemic ventricle and normal systemic arterial saturation.
Among the goals of a nomenclature system in describing complex cardiac malformations, it should conjure up an illustration of the relationships between the systemic and pulmonary veins, the atria, the atrioventricular valves, the ventricular mass, and the great arteries. Each of the principle classification systems, the segmental system and the sequential system, approach this goal. Each has its devotees who are convinced that it should be used, to the exclusion of any other system. Each, of course, can be used to describe virtually any aggregation of anatomic cardiac elements. It is not surprising, however, that in common usage, forms of shorthand have found wide application (eg, the commonly used system to classify subtypes of tricuspid atresia) [11]. Such shorthand monikers take the place of lines of different language that ultimately are intended by their advocates to create an identical illustration. For example, univentricular heart of left ventricular type with absent right atrioventricular connection in situs solitus conjures a picture of the most common forms of tricuspid atresia. Single left ventricle {S,L,L} with restrictive bulboventricular foramen is intended to conjure the same illustration as univentricular atrioventricular connection, DILV with left-sided rudimentary right ventricle and discordant ventriculoarterial connections and restrictive ventricular septal defect. A hierarchical system that borrows from, but is not based entirely on either of the classical systems of nomenclature, has the advantage of acknowledging the spectrum of usually encountered single ventricle anomalies, allowing the clinician to then embellish and refine the description of the specific malformation by proceeding through additional hierarchies. By combining important illustrative terms such as DILV from one system of nomenclature, with familiar shorthand, such as the codes for segmental anatomy from another system of nomenclature, we hope to create an easily usable list of anatomic categories into which the vast majority of single ventricle cardiac anomalies can be fit.
Of note is the decision to include in this system of nomenclature the category single ventricle heterotaxia. Heterotaxia syndrome describes a constellation of defects characterized by malposition of cardiac and abdominal visceral structures. Typically there are anomalies of systemic and pulmonary venous return, atrioventricular (AV) septal defect (AV canal type atrioventricular valve), and frequently pulmonary stenosis or atresia [12]. Patients with heterotaxia syndromes are divided into those with asplenia and those with polysplenia.
More than half of asplenia patients have a single ventricle, and typically they have a single right ventricle (42%) with double-outlet right ventricle (DORV) (82%), pulmonary stenosis or atresia (96%), bilateral superior vena cava (SVC) (71%), and a form of common atrioventricular valve (93%). Systemic arterial outflow obstruction is rare. Total anomalous pulmonary venous connection is typically to an extracardiac vein (64%). Pulmonary anatomy is typically bilateral trilobed lungs with bilateral eparterial bronchi.
Over half of polysplenia patients have two well-developed ventricles, but of those with single ventricles, two thirds have single right ventricle. Interruption of the inferior vena cava and azygous continuation is common (80%). Anomalous pulmonary venous drainage is typically to the right atrium. Only 30% will have DORV. Pulmonary anatomy is typically bilateral bilobed lungs with bilateral hyparterial bronchi.
The surgical approach to any of the spectrum of single ventricle anomalies depends upon numerous anatomic features that can have important impact on the physiology. Thus, it is important that a system of nomenclature makes allowances for coding of such details as normal and abnormal arrangements of systemic and pulmonary venous return, atrial situs, the nature of the atrial septum (intact, restrictive communication, unrestrictive communication, common atrium), the anatomy and functional integrity of the atrioventricular connections, ventricular morphology and function, and the anatomy and function of the outlet(s) from the single ventricle, as well as the anatomy of the great vessels.
Single ventricle hierarchy level 1
Single ventricle hierarchy level 2
Single ventricle hierarchy level 3
Single ventricle hierarchy level 4
Important modifiers can be chosen
Prior palliative surgical and interventional procedures, as well as definitive surgical procedures are located in a separate module of the database.
A separate module of the database will allow for coding of standard intraoperative variables regarding bypass, myocardial protection, etc.
The description of a complex cardiac malformation at the time of the surgical intervention is incomplete without description of prior interventions, operative variables, and postoperative variables. In general, surgical management of hearts with single ventricle anatomy involves a combination strategy based upon palliative and physiologically corrective procedures. Palliative procedures are those that address an imbalance between pulmonary and systemic blood flow, without separating the pulmonary and systemic circulations. Physiologically corrective procedures, are those that are designed to completely separate the pulmonary and systemic circulations (creating in series circulations), achieving the goals of normal volume work for the systemic ventricle and normal systemic arterial saturation.
III. Nomenclature for treatment options
Single ventricle treatment hierarchy level 1
Single ventricle treatment hierarchy level 2
Although associated procedures may be coded for in a separate module of the database, certain associated procedures (listed below) may be important elements of the surgical management of single ventricle hearts.
IV. Diagnosis and procedure short lists
V. Outcome reports
Summary
Although debate continues regarding even the definition of a univentricular or single ventricle heart, it is clear that there are several recognizable subgroups of hearts without two fully developed ventricles that can be described in language familiar to cardiac surgeons utilizing some of the elements of each of the prevailing systems of nomenclature. Thus a system of nomenclature is proposed, that through the use of synonyms may be used to classify the vast majority of single ventricle hearts.
References
This article has been cited by other articles:
|
|
 |
|
  Z. Makhija and R. Sharma Hematologic Alterations in Patients with Functionally Univentricular Hearts World Journal for Pediatric and Congenital Heart Surgery, July 1, 2012; 3(3): 350 - 358. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. L. Backer, H. M. Russell, and B. J. Deal Optimal Initial Palliation for Patients With Functionally Univentricular Hearts World Journal for Pediatric and Congenital Heart Surgery, April 1, 2012; 3(2): 165 - 170. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. M. Giroud, J. P. Jacobs, D. Spicer, C. Backer, G. R. Martin, R. C. G. Franklin, M. J. Beland, O. N. Krogmann, V. D. Aiello, S. D. Colan, et al. Report From The International Society for Nomenclature of Paediatric and Congenital Heart Disease: Creation of a Visual Encyclopedia Illustrating the Terms and Definitions of the International Pediatric and Congenital Cardiac Code World Journal for Pediatric and Congenital Heart Surgery, October 1, 2010; 1(3): 300 - 313. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Khairy, S. M. Fernandes, J. E. Mayer Jr, J. K. Triedman, E. P. Walsh, J. E. Lock, and M. J. Landzberg Long-Term Survival, Modes of Death, and Predictors of Mortality in Patients With Fontan Surgery Circulation, January 1, 2008; 117(1): 85 - 92. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Khairy, N. Poirier, and L.-A. Mercier Univentricular Heart Circulation, February 13, 2007; 115(6): 800 - 812. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. D. Rodefeld, M. Ruzmetov, M. S. Schamberger, D. A. Girod, M. W. Turrentine, and J. W. Brown Staged surgical repair of functional single ventricle in infants with unobstructed pulmonary blood flow Eur J Cardiothorac Surg, June 1, 2005; 27(6): 949 - 955. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
