Wanda C. Miller‐Hance1,2 and Barry D. Kussman3,4 1 Arthur S. Keats Division of Pediatric Cardiovascular Anesthesiology, Department of Anesthesiology, Perioperative and Pain Medicine, Baylor College of Medicine, Texas Children’s Hospital, Houston, TX, USA 2 Department of Pediatrics, Section of Cardiology, Baylor College of Medicine, Texas Children’s Hospital, Houston, TX, USA 3 Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children’s Hospital, Boston, MA, USA 4 Department of Anaesthesia, Harvard Medical School, Boston, MA, USA It is well recognized that the large number, wide spectrum, and complex nature of congenital malformations of the cardiovascular system can make it quite challenging to understand the corresponding structural abnormalities and their associated functional and hemodynamic consequences. This issue can be further complicated by the seemingly bewildering nomenclature and classification systems used in congenital and pediatric cardiology. In addition, the diverse terminology (at times, different terms can even be used to refer to the same anatomic structure, pathologic finding, or lesion) and the numerous classification schemes for categorizing individual anomalies can pose obvious difficulties [1, 2]. This variable taxonomy can be confusing for many, but it is even more perplexing for individuals with limited knowledge or familiarity with the subject, further adding to the intimidating aspects of congenital heart disease (CHD). Many clinicians have acknowledged the critical need for a consistent nomenclature and classification system for CHD that can be widely accepted by all disciplines involved in the care of these patients. As far back as the late 1970s, Shinebourne et al. indicated that “for a nomenclature system to be of value, it needed to be capable of describing any combination of cardiac malformations which may be encountered” [3]. It was also noted that the scheme “should allow for precise classification of such malformations during a patient’s life.” The lack of a consistent nomenclature for describing the various defects or uniform classification scheme for CHD continues to be a source of frustration and confusion in everyday practice. Work in this area is still ongoing but over the last several years significant progress has been made in the development of comprehensive standardized nomenclature and a classification code with the goal of unifying the terminology for pediatric and congenital cardiac care as will be highlighted in this chapter. An understanding of the approaches developed to describe CHD and the elements considered in the morphologic assessment of the heart are important aspects of the practice of pediatric/congenital cardiac anesthesiology. This chapter provides a brief overview of the essential steps involved in anatomic evaluation in CHD. It addresses the segmental analysis of the heart and other relevant components of the diagnostic assessment of the congenitally malformed heart, but it does not dwell on the specifics of one language or taxonomy over the other for describing CHD. Thus, the discussion is not meant to be comprehensive but, instead, it aims to emphasize important points related to the structural evaluation of a patient with CHD. A discussion of the various classification systems for congenital cardiac lesions is beyond the scope of this chapter but is addressed in various chapters throughout this textbook. In the late 1990s, the Society of Thoracic Surgeons, in collaboration with The European Association for Cardiothoracic Surgery, launched the International Congenital Heart Surgery Nomenclature and Database Project with the hope of standardizing the nomenclature used for CHD. One of the goals was to establish a foundation to facilitate multi‐institutional analysis of patient outcomes. This effort led to the adoption of a common nomenclature and classification system of pediatric and CHD by these professional organizations [4]. Concurrently, another international nomenclature system, the European Paediatric Cardiac Code, was developed for congenital cardiac disease [5, 6]. In 2000, The International Nomenclature Committee for Pediatric and Congenital Heart Disease was created, which evolved into a society with various components, including a Nomenclature Working Group. As a result, the International Pediatric and Congenital Cardiac Code (IPCCC) was eventually developed, which allowed for cross‐mapping of the two nomenclature systems for CHD [7]. The aim of the project was to provide an all‐inclusive, internationally accepted, cohesive, and comprehensive system for describing pediatric cardiovascular diseases and CHD using a common nomenclature. This undertaking would ultimately enhance communication among healthcare providers; facilitate education, research, and patient care; and allow for multicenter assessment of clinical outcomes, quality assurance, risk stratification, and many other important benefits. In fact, the IPCCC nomenclature and classification code, in conjunction with the database created by the International Congenital Heart Surgery Nomenclature and Database Project can be freely downloaded from the internet (www.ipccc.net) and is currently being used worldwide. It has served as a resource in extensive surgical outcome analyses involving large numbers of patients. The reader is referred to various publications related to these projects, which address the nomenclature for specific defects, consensus definitions for several complex cardiac anomalies, classification schemes, and applications [8–24]. Ongoing collaborations with the World Health Organization, other international groups addressing standard medical terminology, and the health care industry, are likely to further advance this effort. In fact, this classification system has been accepted for incorporation into the 11th iteration of the International Classification of Diseases (ICD‐11], representing a major step for further standardization of nomenclature across the globe [23, 25]. Despite the remarkable efforts to establish a comprehensive standardized nomenclature and hierarchical classification system, it is well recognized that ongoing debate and discussion will continue to take place in clinical practice while these schemes continue to be refined [24]. Several publications have addressed, in detail, the applications of an organized anatomic analysis in the diagnosis of CHD and the steps involved in a comprehensive structural assessment [3, 26–33]. The segmental approach, as initially described by Richard Van Praagh and colleagues in the 1960s, relies upon an examination of cardiac anatomy in a series of segments or “building blocks” [34, 35]. These major units are considered the essential components of the heart, whether normal or diseased [26]. The anatomy of the various cardiac segments and their relationships to each other represent the foundation of the segmental analysis. Robert Anderson and colleagues expanded upon this concept but reduced the emphasis on relationships by proposing a scheme based on blood flow through the heart, which focused on characterizing the connections between the segments [28, 32]. Based on this approach, the sequential segmental approach was developed. The detailed methodology used in the sequential segment‐by‐segment approach allows for a stepwise examination of all cardiac segments by navigating through the heart in the direction of blood flow from the atria to the ventricles to the great arteries. The three main segments are the veins and atria, ventricles, and great arteries. The units are joined to each other by two connecting cardiac segments (or junctions): the atrioventricular (AV) junction (AV canal region), which connects the atria to the ventricles, and the ventriculoarterial (VA) junction (infundibulum/conus arteriosus), which connects the ventricles to the great arteries (Figure 7.1). This systematic examination offers an organized and rigorous method that facilitates the defining of congenital cardiovascular defects. The benefit of this analysis is that it can be applied to all congenital cardiac malformations, although it is particularly useful for characterizing complex defects. The merits of this approach are reflected in the fact that this system has been incorporated into clinical use within various disciplines related to CHD and applied in the evaluation of fetuses to adults [36–42]. Historically, and based on the development of the nomenclature as previously described, there have been two major philosophies regarding the segmental assessment of the congenitally malformed heart. These schools of thought have been led by two world‐renowned leaders in the field: Drs. Richard Van Praagh and Robert H. Anderson. Colloquially, these have been referred to as the “Van Praaghian” and “Andersonian” nomenclature systems. The Van Praagh classification system was pioneered and evolved in Boston, Massachusetts and is widely used in North America, whereas that by Anderson was developed and is conventional throughout Europe. Figure 7.1 Sequential segmental analysis. Figure depicts the key components of the sequential segmental analysis: the three major building blocks (atria, ventricles, arterial trunks) and their joining segments (atrioventricular and ventriculoarterial junctions). (Source: Ms. Gemma Price. Reproduced with permission.) Although these approaches to describe cardiac anatomy share common elements, there are many important differences. A significant one relates to the shorthand notation used in the Van Praagh system to facilitate communication among providers involved in the diagnosis and management of patients with CHD as described to follow. Other divergent viewpoints include terminology and the methods used to describe morphology and cardiac pathology. The disparities between the two major schools of nomenclature have created disagreements among advocates and specialists in the field, sometimes resulting in heated arguments and controversies between the different camps. Efforts have been made to reconcile these two approaches in recognition of the fact that both of these systems have virtues and that, in many ways, they may complement each other [43, 44]. The reader is referred to the excellent resource entitled Atlas of Congenital Heart Disease Nomenclature: An Illustrated Guide to the Van Praagh and Anderson Approaches to Describing Congenital Cardiac Pathology for an in‐depth discussion on these two nomenclature systems [45]. Although clinicians have generally been divided as followers of the teachings of one school or the other, many practitioners have opted for a stance somewhere in the middle recognizing that the likelihood of implementing a single, universally accepted system is remote, and they continue to see merits in the various schemes currently used [46]. It should also be recognized that even these systems have evolved in their thinking over time [47]. In some cases, an alternate approach has been to simply describe the anatomy without regard for either system. Despite personal preferences, the expectation in most cases is for providers of CHD patients to be fluent in these nomenclature systems. It should be emphasized that regardless of the nomenclature or scheme favored, it is more important that each institution has a uniform and consistent approach for describing and referring to the various defects or structural abnormalities to optimize communication among all practitioners involved in patient care. A unique feature of the Van Praagh style is the use of a three‐letter notation, or code, enclosed in braces or curly brackets {X,X,X}. The letters in the set are abbreviations separated by commas that represent the sidedness or anatomical organization (referred to as “situs”) of the three main cardiac segments of the heart in venoarterial sequence (atria, ventricles, great arteries) [2, 30]. In essence, the segments are to be considered in terms of the following: The possibilities for each segment are denoted by different letters as shown in Box 7.1 (also refer to the discussion later in the chapter). The normal anatomic configuration would be indicated by the notation coding of {S,D,S}. This notation corresponds to visceroatrial situs solitus or {S,‐,‐} with the vena cavae and the morphologic right atrium on the right side, and the morphologic left atrium on the left side; D‐loop ventricles {‐,D,‐} where the right ventricle is right‐handed, rightward and anterior to the morphologic left ventricle, whereas the left ventricle is left‐handed, leftward and posterior as a result of a cardiac tube curved rightward (dextro or D‐loop); and normal situs solitus of the great arteries {‐,‐,S} where the pulmonary artery is located anterior and leftward to the aorta. This shorthand system does not specify the “alignments” (AV or VA) between the cardiac segments, a term preferred by Van Praagh over “connections,” nomenclature favored by Anderson, to describe the segments between the atrial and ventricular chambers, and the ventricles and great arteries. In this system, the segmental alignments are noted separately [30, 31, 48]. As per Van Praagh, “significant abnormal VA alignments such as transposition of the great arteries (TGA) are indicated before the braces: TGA {‐,‐,‐},” while “important abnormal segmental connections and other associated cardiovascular anomalies are listed after the braces: {‐,‐,‐} with straddling tricuspid valve and ventricular septal defect of the AV canal type” [2]. At first glance, this nomenclature system may appear relatively straightforward and easy to understand, in fact, it has been widely utilized in many aspects of diagnostic imaging including echocardiography and radiology [41, 42]. However, the combination of letters can be somewhat complex to decode or interpret, particularly for individuals who are not familiar with the shorthand nomenclature. In addition, although the segmental classification scheme can be used to describe most congenital heart defects, some anomalies, such as heterotaxy syndromes, can be difficult to define precisely using this scheme. Therefore, even though it is well recognized and widely applied, this system has not been universally embraced. Some consider a more descriptive approach less likely to cause confusion, particularly, in the case of complex CHD [49]. For many decades, and with both the Van Praagh or Anderson systems, the segmental approach has been used to characterize congenital anomalies that affect the heart and related vascular structures [3, 26]. The steps taken in this segmental analysis are described in the sections that follow. The aspect of CHD evaluation related to cardiac position can be confusing because it is described differently by various sources and the terminology used (Figure 7.2). One approach describes the cardiac position as the spatial location of the majority of the cardiac mass within the thoracic cavity, using the sternum as the midline reference. The term levocardia indicates that the heart occupies most of the left hemithorax (i.e., a left‐sided heart), dextrocardia indicates that the heart is in the right hemithorax (i.e., right‐sided heart), and mesocardia indicates that the heart is in the midline position. In addition, a distinction is made between primary and secondary dextrocardia; the former is due to a structural cardiac defect, whereas the latter results from the heart being displaced by extracardiac conditions. A second approach specifies both the cardiac position and orientation, as these are not to be considered synonymous when describing cardiac location. In this scheme, as in the previously mentioned approach, cardiac position refers to the overall location of the cardiac mass relative to the midline; however, the terminology is used differently. In this algorithm, the terms levoposition, dextroposition, and mesoposition are used to indicate that the cardiac mass is predominantly in the left hemithorax, right hemithorax, or middle, respectively. Furthermore, the terms levocardia, mesocardia, and dextrocardia are used to describe cardiac orientation, or alignment from the base (great arteries) to the apex (ventricular apex), instead of cardiac position. Levocardia indicates that the heart’s cardiac apex points to the left side of the chest, mesocardia indicates that the heart’s cardiac apex points straight inferiorly, and dextrocardia indicates that the heart’s apex points to the right. Displacement of the heart into the right or left thoracic cavity is described as dextropositioning or levopositioning, respectively. Other terminology used related to the orientation of the cardiac apex is “levoversion” if it points to the left and “dextroversion” if it points to the right. In most cases, the cardiac position and base‐to‐apex orientation are in agreement, meaning that both are aligned in the same direction. For example, in the case of the normal heart, the cardiac mass is in the left hemithorax and the ventricular apex is directed towards the left. Consequently, the distinction between these two parameters is irrelevant in most cases. However, when the heart is displaced, for example by the presence of abdominal contents in an infant with a congenital left diaphragmatic hernia, the cardiac mass may be pushed to the right hemithorax (dextroposition), while the cardiac apex still points to the left (levocardia). In such cases, the two descriptors should be noted. At times, these features are critically important for surgical planning. It should be recognized that cardiac position and apex orientation cannot be utilized to establish cardiovascular anatomy, nor do these have a predictable relationship to cardiac pathology. A good example of this issue is the patient with dextrocardia in which complex CHD may be found or in some instances, a structurally normal heart.
CHAPTER 7
Nomenclature and Anatomic Evaluation in Congenital Heart Disease
Introduction
Congenital heart surgery nomenclature and database project
Approaches for describing congenital heart disease
The “Van Praaghian” and “Andersonian” nomenclature systems
The Van Praagh notation
Segmental approach to diagnosis of congenital heart disease
Cardiac position and apex orientation
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