Controversies in the Description of Congenitally Malformed Hearts

The following sections are included:

• Foreword

• Contents

In this short book, we will review some of the controversies which persist concerning the most appropriate means of describing congenitally malformed hearts. Although many lesions could be cited as continuing to produce problems of nomenclature, for the purposes of our discussion, we will limit ourselves to four malformations. The first is the one in which concepts derived from development have, perhaps, produced the most confusion. This is the variant of atrioventricular septal defect which exists in tandem with a common atrioventricular junction. In our approach to this lesion, as with the subsequent malformations, we will show how concepts derived from presumed, albeit unproven, morphogenetic mechanisms have produced markedly inappropriate accounts of the underlying anatomy. The other lesions we will then address are those hearts which are found in the setting of isomeric atrial appendages, the time-honoured malformation of tetralogy of Fallot, where we will discuss its vexed relationship with double outlet right ventricle, and the hearts which are unified because they possess a univentricular atrioventricular connection. In our approach to all these lesions, we will make continued reference to certain common philosophic principles. In this introduction, therefore, we will chart the anatomic background to these principles which guide our analysis, discussing specifically the morphologic method and the sequential segmental approach.

The group of congenitally malformed hearts to be described in this chapter has unmistakable morphology. It is characterized by deficient atrioventricular septation in the setting of a common atrioventricular junction. When the abnormal junctional morphology (Fig. 1) is contrasted with the normal (Fig. 2), the difference is striking. Why, then, does the lesion, in its various guises, continue to generate conflicts of opinion concerning the basic a anatomy,^1,2 and why has there been such difficulty in reaching consensus on the most appropriate terms for description²?

The following sections are included:

• INTRODUCTION

• SYMMETRY VERSUS LATERALIZATION

• MORPHOLOGY OF THE ATRIUMS RELEVANT TO ISOMERISM

• MORPHOLOGY OF HEARTS WITH ISOMERIC ATRIAL APPENDAGES

• SYNTHESIS OF FINDINGS

• DEVELOPMENTAL CONSIDERATIONS

• REFERENCES

The following sections are included:

• INTRODUCTION

• UNIFYING PATHOLOGY

• VARIATIONS IN THE CHARACTERISTIC ANATOMY

• CONTROVERSIAL ASPECTS
  • The right ventricular outflow tract or infundibulum
  • Fallot’s tetralogy versus double outlet right ventricle

• DEVELOPMENTAL CONSIDERATIONS

• REFERENCES

The following sections are included:

• INTRODUCTION

• THE ATRIOVENTRICULAR JUNCTIONS

• DESCRIPTION OF VENTRICULAR MORPHOLOGY

• THE UNIATRIAI BUT BIVENTRICULAR CONNECTION

• THE OVERALL NATURE OF THE VENTRICULAR MASS

• DEVELOPMENTAL CONSIDERATIONS

• REFERENCES

The following sections are included:

• Index