Sequential segmental analysis

INTRODUCTION It might reasonably be thought that those who diagnose and treat patients with congenitally malformed hearts would, by now, have reached consensus concerning the most appropriate way of describing the malformations with which they are confronted. It is certainly the case that nomenclature is far less contentious now than was the case a decade ago. It would be a brave person, nonetheless, who stated that the field of description and categorization was now fully resolved. There are still major differences of opinion as how best to cope with certain topics, such as those patients who have so- called visceral heterotaxy. In this review, we outline a system for description that accounts well for such topics. Indeed, it provides a means of cataloguing and describing all congenital cardiac malformations, even if the combination of lesions has never previously been encountered. In reality, there is no right or wrong way of describing the hearts, simply different ways.[12] Even these different ways have been mitigated to considerable extent by the cross-mapping of existing systems.[3] The success of cross-mapping, nonetheless, should not detract from the need to resolve ongoing differences according to the nature of the abnormal anatomy as it is observed. In this review, we provide such accounts of the phenotypic features of the so-called cardiac segments. We show how this approach then provides the template for categorising the arrangements in all patients with congenitally malformed hearts. THE BASIC APPROACH TO CATEGORISATION In terms of its basic make-up, the heart has three building blocks, namely the atriums, the ventricular mass, and the arterial trunks. The first systems of categorization based on recognition of the limited potential for variation in each of these cardiac segments were developed independently in the 1960s by two groups: one based in the United States of America, and led by Richard Van Praagh,[1] and the other, from Mexico City, headed by Maria Victoria de la Cruz.[4] Both of these systems concentrated on the different topological arrangements of the components within each cardiac segment. At that time, these approaches were understandable, since it was often difficult with the diagnostic techniques then available precisely to determine how the adjacent structures were linked together. All of this changed with the advent of cross-sectional echocardiography. Since the mid 1970s, it has been possible with precision to determine how atriums are, or are not, joined to ventricles, and similarly to establish the precise morphology found at the ventriculo-arterial junctions. Thus, the system with which we have been involved was produced concomitantly with the development of echocardiography, with attention concentrated on the potential variations to be found across the atrioventricular and ventriculo-arterial junctions. The system was called, and is still called, sequential segmental analysis.[25–7] It should not be thought that the topology of the segments themselves is ignored when making such analysis. Junctional connections cannot be established without initial knowledge of segmental topology. During its evolution, the system has followed some basic and simple rules. From the outset, categories have been based on recognizable anatomical features, eschewing speculative embryological assumptions. Emphasis is placed on the morphology of the cardiac components, the way they are joined or not joined together, and the relations between them, as three different facets of the cardiac make-up. Any system that separates these features one from the other, does not use one to determine another, and describes them with mutually exclusive terms, must perforce be unambiguous. The clarity of the system then depends upon its design. Some systems opt for brevity, with formidable codifications constructed to achieve this aim.[8] But clarity is surely more important than brevity? We do not shy, therefore, from using words to replace symbols, even if this requires several words. Wherever possible, we strive to use words that are as meaningful in their systematic role as in their everyday usage. In the desire to achieve optimal clarity, changes have been made in our descriptions over the years. We make no apologies for these changes, since their formulation, in response to valid criticisms, has eradicated aspects of the system that were initially illogical. Having expunged these aspects, it is our belief that the system now advocated is entirely logical, and is also simple. THE ESSENCE OF SEQUENTIAL SEGMENTAL ANALYSIS The system depends first upon the establishment of the arrangement of the atrial chambers. Attention is then concentrated on the anatomical nature of the junctions between the atrial myocardium and the ventricular myocardial mass. This feature, described as a type of connection, is separate from the additional feature of the morphology of the valve or valves that guard the junctions [Flow diagram]. The normally constructed heart possesses 2 atrioventricular junctions, usually with each junction guarded by its own atrioventricular valve. On occasion, the two junctions can be guarded by a common valve. In order to achieve such analysis of the junctions, it is essential first to have determined the structure, topology, and relationships of the chambers within the ventricular mass. Having dealt with the atrioventricular junctions, the ventriculo-arterial junctions are analysed according to how the arterial are joined to the ventricular mass, with the morphology of the arterial valves their junctions. attention is to the morphology of the and to the relationships of the arterial trunks. segmental connections have been and of appropriate a is then made of all and in this are such features as the of the the of its and the arrangement of the and features in sequential segmental in the system is the to the morphology of the atriums and ventricles, with the of of the arterial from the This is not as as it since in congenitally malformed hearts, the chambers or arterial some of the features that most them in the the most feature of the in the heart is the to it of the with connection, for such a In of this of connection, it is still possible to the of this type the now for recognition of the cardiac chambers and the the that structures should be in terms of their own of the heart that is therefore, should not be on the of this is to the atrial the connections of the are as of or as the do not to their The morphology of the is also of when the is as in the of a common the atrial is as a since it provides no features for the right as to the There one of the atrial chambers in our has been and on the of the morphology of its junction with the of the has to between right and This is the The right has the of a and over a junction with the of the most feature is the within the that all the atrioventricular junction right The show the of the and right atrioventricular junctions of the heart as from the atriums with a to the atrioventricular junctions. show in the right the within the the all the of the valve. In the in the are within the that the of the is in is and It has a junction with the of the The are within the with the of the also the as it with the of the The also its when to the ventricular mass, which from the atrioventricular to the ventriculo-arterial junctions. the ventricular as there are two of ventricles, no how malformed they is if they are analysed as three are, the from the atrioventricular junction to the of the atrioventricular The is the The is the the of the arterial valve. these three components, it is the that is most in as well as in malformed and ventricles, and which most right from This is the case even when the components as ventricles, which their and components The the right which from the atrioventricular to the ventriculo-arterial junctions with the to show its three The are the most of these The the three of the of the by its This also from the atrioventricular to the ventriculo-arterial junctions are its most feature, and it from the right In the heart there is and from a The arterial are in from the with the and to the On the and of the there is still a to be a ventricular This is the of the right of its order fully to must also be of its It is then to the way that the two themselves are within the ventricular mass. This feature is described in terms of ventricular topology, since two basic are found that cannot be changed without the ventricular components and The two are of each can be in terms of the way the of the can be placed upon the of the right In the right of the of its in the of the right can be placed on the such that the the and the the The of the then in within the it is the right that is as the for the of The therefore, can be described as right ventricular topology. The the of the right is then described as ventricular topology. In this in the or in the of congenitally found with atrial it is the of the that on the of the right with the in the and the in the two topological can be of the in by the ventricular make-up, topology, and are features of the On occasion, all need separate description in order to potential for hearts be found with a this be a right or is that it cannot be with There nonetheless, a of ventricular morphology that is found in hearts a This is when the is of right or is and by a has morphology of on the of their the need to use the terms or for description of hearts one and one Any to such chambers from ventricular must to a system of nomenclature that is and hearts with a should be described as that the connections across the atrioventricular junctions can be in more The heart is in to show that atrioventricular valves the ventricular which also to We were to a ventricular The and the of the this heart as a of the morphology of the arterial there are no features that to be from a or from a common or arterial The of the nonetheless, is to these The to at one and the of the The to or one or other, of the common the and arterial in the of the of the In such it is to with the is common or Even in the that have one of these of the has to the nature of the arterial The of system of sequential analysis must be establishment of the arrangement of the atrial since this is the for analysis. this arrangement is on the of the morphology of the junction of the with the of the atriums, then since all hearts have two atrial each of which can be of right or there are possible The most common is the also called in which the right is and the is The is the of the It is often called even the atrial chambers are not In these two the are with the right to one and the to the The two arrangements do not show such there is of the atrial In these the two are of each other, with at their junctions with the of the atriums on of right type or The when analysed on the of the extent of the to the atrioventricular there are possible ways for arrangement of two atrial the the arrangement of the be by of the extent of the the In when using and the of the within the this feature should now be recognizable using cross-sectional echocardiography, from the In most it is to on This is the morphology of the is in with the arrangements of the and In patients with in words with the and it is for there to be between the of the the are in then usually the are Even when there is such the and are and it is for the arrangement to show with the morphology of the The of therefore, can be from the The is and it it has been by its making the In the right is and is by its it has of The of are then in with the arrangement of the atrial to those from arrangement can also usually be by using cross-sectional to the a to each other, and to the which not as as does The can be according to their of the atriums are then without the and to of the with the on the of the right there is then the usually to the of the with the in in those with of the right atrial and or with the in those of the atrial of the right atrial is with of the of the atrial is with with of the atrial therefore, are together, from the cardiac the of the This approach is less than describing the in terms of of the atrial since the between of the right atrial and of the and between of the atrial and is far from of the right and in describes is and to attention upon the THE In the the atrial myocardium is with the ventricular the of the and than at the of the of the of is at these junctions by the atrioventricular In order to the morphology of the atrioventricular junctions in abnormal hearts, it is first to the atrial it is to the morphology of the ventricular as to establish which is to which this to it is then possible to the of or across the junctions, and to determine the morphology of the valves the atrioventricular junctions. In hearts with malformations, it is also on occasion, to the precise topology of the ventricular mass, and to the relationships of the OF OF THE on the way that the myocardium of the atrial chambers is joined to the ventricular myocardium the of the atrioventricular junctions. The of the atrial chambers are to the ventricular the atrioventricular In since there are two atrial there is the for two atrioventricular which be and This is the case of the junctions themselves are guarded by two valves or a common valve. of the junctions be by this does not the in such a there are still two potential atrioventricular In some hearts, in this is not This is one of the connections is The atrial myocardium on that then has no with the ventricular from the ventricular by more than of the of the atrioventricular This arrangement is the most common atrioventricular atrioventricular connections are in this all hearts one of three In the first by far the most the of each atrial is in or and with the of The feature of the is that one of the ventricles, if two are is in with the atrial There is then even This is when one atrioventricular is and the atrioventricular a is to two This arrangement is There are possible arrangements in hearts with each joined to its own on the morphology of the chambers together. The first is when the atriums are joined to appropriate ventricles, of the topology or of the ventricles, or of the morphology of the valves the junctions. This arrangement atrioventricular and with usually atrial or in the arrangement The arrangement is the of the It is of relationships or It atrioventricular it is the atrial that are in patients with atrioventricular the are in their right topology The how atrioventricular connections can is and without atriums with usually are joined to a ventricular with right topology, atriums with are joined to a ventricular with topology. when these are not it is not also to the topology of the In this the arrangements are that without atrioventricular first two arrangements are found when the atrial are The atrioventricular arrangement is found in hearts with be they of right or This arrangement cannot be described in terms of or it is a in its own which is is of ventricular relationships and atrioventricular and requires of ventricular topology to make the description There are also possible arrangements that atrioventricular connections The first is when the of atrial chambers are to the This is called atrioventricular connection, of the and atrioventricular junctions are guarded by two atrioventricular valves or a common valve. The two arrangements when the or atrioventricular is The atrioventricular connections are not of ventricular relationships and also of atrial and ventricular Thus, or atrioventricular connections can be found with usually or atrial and with the atriums to a right a or to a morphology must therefore, be described in those hearts in which the atrial chambers are joined to one in these hearts, one is joined to the atriums, in most of them there is a This of be of to the the is a and the possesses right ventricular the is with the Even more hearts be found with a ventricular of morphology In or right be when the is to be The some of the potential atrioventricular In reality, these can with arrangement of the atrial with or atrioventricular connections and with or right ventricles, or and The are with arrangement of the atrial simply for the in the are for The variation in ventricular morphology for hearts with of one atrioventricular There is with to the of the and with ventriculo-arterial and hearts, therefore, the need for sequential segmental analysis and OF THE the in which the atriums are joined to the across the atrioventricular junctions accounts for the way in which the atrial the of the ventricular mass. The morphology of the valves the atrioventricular is of this feature, within the by the of the junctions the of atriums are joined to the ventricular mass, the and atrioventricular junctions be guarded by two by one valve and one by a common or by and arrangements of the valves can be found with and or of the or valve be in the of a potential as to atrioventricular common valve and atrioventricular junctions, of its valve when its is to of a within the ventricular mass. It when the atrioventricular junction is to on of a a or a common valve can can or can and and valves in the one atrioventricular is then the possible of are This is the of is The valve is usually in its to one it or and the of valve that has additional on since the of of the atrioventricular junction to the the precise in which the atriums and are joined together. with two in which one valve is are between those on the one on the atrioventricular most of junction is to a that is also joined to the the is the junction is to a not joined to the then the is more to or and is in one of these describing atrioventricular the and are in hearts with atrioventricular connections separate junctions, each guarded by its own valve. In this the valve is found in the right and the valve in the In hearts with atrioventricular connections with a common in it is to the common valve as and components, even when it is right and and components, on the to the atrioventricular In hearts with the two valves are as and valves than as or as is the case when one is can be described as right or Even in the the ventricular relationships are The are more or less to the right and with the of the ventricular in The are more or less with the between them in The between these two components, with the between the and It is that there is a desire to have a to such We use the of ventricular topology for this this the right is in the way the of the can be to its such that the is in the and the in the with the the This right and In with usually atriums and atrioventricular the ventricular topological ventricular topology is usually found with the combination of atriums and atrioventricular these are can such ventricular relationships as a feature of the topology, we for and should it be we the of the three ventricular components and to each In hearts with arrangements in the of atrial arrangement and atrioventricular the of the are usually that the right ventricular and components are to the right of their ventricular the of In such hearts with atrial arrangement and atrioventricular the ventricular a of topology. In with the of the right also be right in with atrioventricular relationships are described and from the connections and the ventricular topology, then of these and hearts be difficult to diagnose or to In to these hearts, we have how description of ventricular topology is essential when for the combination of with atrioventricular This is in this the terms would be to the heart in which the was to a right as well as the heart in which the was to a The arrangements are simply by describing also the ventricular topology. Both the and the relationships of need to be described in hearts with atrioventricular the relationships are of the connections and the ventricular the right is and right in it can be and without in way the and in hearts with the of the a role in the we the of ventricles, therefore, we simply for their to the when of and On occasion, it also be to the of and components of THE concerning the ventriculo-arterial junctions upon the to between the way the arterial from the ventricular as to their relations to each other, with on the nature of the their arterial these features are described the of the then all potential for is OF THE THE with analysis of the atrioventricular junctions, it is to for the way the and the nature of the valves the ventriculo-arterial junctions. There are possible of ventriculo-arterial connections when the from a and the from a right be the or The arrangement the from a right or its and the from a or its ventriculo-arterial is found when are to the which be of right ventricular or ventricular with atrioventricular arterial valves are to the the of their The ventriculo-arterial is from the This one of common when are a common arterial valve to one that to the at one and the of the arterial when it is not possible to of within the The of are with or with two categories those arrangements in using it is not possible to establish the precise of the arterial to a ventricular its ventricular can be is found to be then the is with the of valve. It is also in hearts with to the ventricular of the arterial This be from a right or a more usually the the its from There are for the valves at the ventriculo-arterial than at the atrioventricular junctions. common arterial valve can with a type of namely common arterial of arterial valve is it has no Thus, the possible are two one or of which or one and one valve. with atrioventricular the of of arterial valve the precise of the arterial from the ventricular mass, the or to the the of its making this as with atrioventricular we on the of the more usually are usually described at and systems for nomenclature have been constructed on this It is our to arterial relationships in terms of and In this is described to the in terms of of a using the simple terms and in their as we then that these arterial and no the of the arterial from the ventricular mass, or the morphology of the ventricular we have no of From the of of the arterial the are for the to the as it from the of the ventricles, or for the two to in It is to these are most with ventriculo-arterial and with or there is no in these In all hearts, the to the of the The of the depends on it to the right or of the The of the is to the The are no more and no less than the components of the ventricular mass. the structures are for they are, and their morphology described as then provide no in recognition and The morphology of the ventricular is for each can a as its and then each arterial valve can be to have a as a the of the ventricular in the of have three of the the and of the of the arterial The is the ventricular The is the heart a that separates the of the arterial from those of the atrioventricular We this the The is the that separates the two which we the or It is possible, for arterial valves to be from atrioventricular valves by the for the arterial valves to be in with one of the of the In most hearts, some of the is that between the of one of the arterial and the atrioventricular it is the ventricular of the that is a there is between the of the valve and the arterial valve by the the arterial valve is or on the ventriculo-arterial connections In the the right ventricular of the that there is on the of the there is usually a or in the right are to the right then the can in its between the of the atrioventricular and arterial But hearts in which arterial valves are to the right have between at one arterial valve and atrioventricular valve. It to the of of arterial from the right in this This is of the when one feature of cardiac morphology is determined on the of a arterial their from the the is for there to be between the of arterial valves and atrioventricular Even in some the in or in its It is usually the of the therefore, that is the feature of the of of the and morphology from the of the arterial there are possible there be a with between the of the and atrioventricular there be a with between the and the atrioventricular there be with of between the of the arterial and atrioventricular there be with between the arterial and the atrioventricular In these terms are not it is also to which arterial valve from which This the that morphology is of the ventriculo-arterial The of patients with congenitally malformed hearts have their cardiac segments joined in with morphology and In such a the be the It is also nonetheless, to attention to the of the heart within the and the of the cardiac that the heart be the abnormal of the heart within the is and should not be to a This is not to the of abnormal cardiac if to in of the that the heart is no concerning its sequential segmental analysis is to establish the cardiac structure, and not the way The heart can be in the in the right or in the The cardiac can then to the to the or to the The of the is of cardiac Both of these features are of the arrangement of the atrial and of the and a with should be by even the or or The system we have described is and accounts for all malformations, even if a combination of lesions has never previously be or It depends on recognition of the anatomy as it is observed. the available techniques of all the features described should be as by the as by the Thus, there is that concerning description of congenitally malformed hearts now be as of the of of our This is based on the constructed for the of by one of with and and to be by We are to who produced the for all the to be in this review, and in the of the