The nomenclature, definition and classification of cardiac structures in the setting of heterotaxy

Abstract

In 2000, The International Nomenclature Committee for Pediatric and Congenital Heart Disease was established. This committee eventually evolved into the International Society for Nomenclature of Paediatric and Congenital Heart Disease. The working component of this international nomenclature society has been The International Working Group for Mapping and Coding of Nomenclatures for Paediatric and Congenital Heart Disease, also known as the Nomenclature Working Group. The Nomenclature Working Group created the International Paediatric and Congenital Cardiac Code, which is available for free download from the internet at [http://www.IPCCC.NET]. In previous publications from the Nomenclature Working Group, unity has been produced by cross-mapping separate systems for coding, as for example in the treatment of the functionally univentricular heart, hypoplastic left heart syndrome, or congenitally corrected transposition. In this manuscript, we review the nomenclature, definition, and classification of heterotaxy, also known as the heterotaxy syndrome, placing special emphasis on the philosophical approach taken by both the Bostonian school of segmental notation developed from the teachings of Van Praagh, and the European school of sequential segmental analysis. The Nomenclature Working Group offers the following definition for the term "heterotaxy": "Heterotaxy is synonymous with 'visceral heterotaxy' and 'heterotaxy syndrome'. Heterotaxy is defined as an abnormality where the internal thoraco-abdominal organs demonstrate abnormal arrangement across the left-right axis of the body. By convention, heterotaxy does not include patients with either the expected usual or normal arrangement of the internal organs along the left-right axis, also known as 'situs solitus', nor patients with complete mirror-imaged arrangement of the internal organs along the left-right axis also known as 'situs inversus'." "Situs ambiguus is defined as an abnormality in which there are components of situs solitus and situs inversus in the same person. Situs ambiguus, therefore, can be considered to be present when the thoracic and abdominal organs are positioned in such a way with respect to each other as to be not clearly lateralised and thus have neither the usual, or normal, nor the mirror-imaged arrangements."The heterotaxy syndrome as thus defined is typically associated with complex cardiovascular malformations. Proper description of the heart in patients with this syndrome requires complete description of both the cardiac relations and the junctional connections of the cardiac segments, with documentation of the arrangement of the atrial appendages, the ventricular topology, the nature of the unions of the segments across the atrioventricular and the ventriculoarterial junctions, the infundibular morphologies, and the relationships of the arterial trunks in space. The position of the heart in the chest, and the orientation of the cardiac apex, must also be described separately. Particular attention is required for the venoatrial connec...

Laterality Defects Other Than Situs Inversus Totalis in Primary Ciliary Dyskinesia

“…Classifi cation of these defects is complicated because diff erent specialists tend to use diff erent defi nitions for SA and heterotaxy. [4][5][6][7][8] Some clinicians interchange the terms "situs ambiguus" and "heterotaxy"; however, cardiologists defi ne heterotaxy as a subset of SA with specifi c congenital heart defects (eg, common atrium, levo-transposition of great arteries). Geneticists have expanded the cardiology definition to include combinations of abdominal defects (eg, asplenia, polysplenia) or vascular defects (eg, interrupted inferior vena cava).…”

Polysplenia or Left Isomerism?

“…We propose that the evidence now supports a more effective description of splenic syndromes in terms of right or left isomerism, based ideally on knowledge of the morphology of the atrial appendages. If, however, the appendages are not visualized on imaging or at the time of cardiac surgery, the evidence at hand strongly supports the notion that the morphology of these structures can be inferred on the basis of associated congenital malformations (2,3).…”

Clinical care for primary ciliary dyskinesia: current challenges and future directions

“…Studies have used different definitions and classification systems for heterotaxy [12,[78][79][80][81][82][83], despite standardisation efforts [84]. While some authors group situs inversus and situs ambiguous under the umbrella of heterotaxy [82], others believe it should be restricted to situs ambiguous only [2,81,83,84].…”

“…While some authors group situs inversus and situs ambiguous under the umbrella of heterotaxy [82], others believe it should be restricted to situs ambiguous only [2,81,83,84]. Using the latter definition, KENNEDY et al [83] reported that over 6% of PCD patients presented with heterotaxy.…”