DEXTROCARDIA AND ISOLATED LAEVOCARDIA. I. ISOLATED LAEVOCARDIA

Diagnosis of Dextrocardia with a Pictorial Rendition of Terminology and Diagnosis

A significant number of patients with dextrocardia and other cardiac malpositions have other congenital heart defects (CHDs). The incidence of CHDs in subjects with cardiac malpositions is significantly greater than that in normal children, and the prevalence varies with the associated visceroatrial situs. The most useful approach to diagnosis is segmental analysis. Firstly, dextroposition should be excluded. In segmental analysis, the visceroatrial situs, ventricular location, status of atrioventricular connections, the great artery relationship, and conotruncal relationship are determined with the use of electrocardiogram (ECG), chest X-ray, and echocardiographic studies, and, when necessary, other imaging studies, including angiography. Following identification of the afore-mentioned segments, the associated defects in the atrial and ventricular septae, valvar and vascular stenosis or atresia may be determined by a review of the historical information, physical examination, and analysis of chest roentgenogram, ECG, and echocardiographic studies. Along the way, a pictorial rendition of the terminology and diagnosis of cardiac malpositions is undertaken.

Prenatal diagnosis of isolated levocardia and a structurally normal heart: two case reports and a review of the literature

Isolated levocardia (ILC) is a developmental abnormality involving an abnormal abdominal situs with a normal cardiac situs. This abnormality is especially rare when it is associated with a normal cardiac anatomy. The prenatal diagnoses of seven cases were reported in the English literature. This report presents two cases referred to the authors' echocardiography laboratory for maternal diabetes mellitus in case 1 and suspected dextrocardia in case 2. In both cases, ILC with a structurally normal heart was diagnosed prenatally. The child in the first case was found to have a normal inferior vena cava (IVC) prenatally. Postnatally, he was found to have intestinal malrotation with duodenal obstruction and multiple splenules. Interruption of the IVC was shown by abdominal ultrasound. The child in the second case was found to have an interrupted IVC with azygos continuation prenatally. Postnatally, intestinal malrotation with no evidence of intestinal obstruction or asplenia was detected. Neither of the cases had reported cardiac arrhythmias. Early diagnosis is crucial in these cases due to the high incidence of associated anomalies and potential life-threatening conditions. Management of patients with ILC is dictated by the associated anomalies. Long-term follow-up assessment is recommended for these patients to monitor the development of rhythm abnormalities.

The cardiac malpositions

Dextrocardia was known in the 17th century and was 1 of the first congenital malformations of the heart to be recognized. Fifty years elapsed before Matthew Baillie published his account of complete transposition in a human of the thoracic and abdominal viscera to the opposite side from what is natural. In 1858, Thomas Peacock stated that "the heart may be congenitally misplaced in various ways, occupying either an unusual position within the thorax, or being situated external to that cavity." In 1915, Maude Abbott described ectopia cordis, and Richard Paltauf's remarkable illustrations distinguished the various types of dextrocardia. In 1928, the first useful classification of the cardiac malpositions was proposed, and in 1966, Elliott et al's radiologic classification set the stage for clinical recognition. The first section of this review deals with the 3 basic cardiac malpositions in the presence of bilateral asymmetry. The second section deals with cardiac malpositions in the presence of bilateral left-sidedness or right-sidedness. Previous publications on cardiac malpositions are replete with an arcane vocabulary that confounds rather than clarifies. Even if the terms themselves are understood, inherent complexity weighs against clarity. This review was designed as a guided tour of an unfamiliar subject.

Isolated levocardia: prenatal diagnosis and management

Isolated levocardia (IL) is a rare condition of situs anomaly in which there is a normal left-sided heart (levocardia) with dextro position of the abdominal viscera. IL has been reported in children and adults with complex cardiac defects, whereas there are only few published reports regarding the prenatal diagnosis of IL. We report two prenatal cases of IL diagnosed by ultrasonography and magnetic resonance imaging (MRI). In both cases, fetal cardiac function remained within the normal range throughout pregnancy, and no treatment for the heart was required after birth. For the dextro position of abdominal viscera, one case was followed without any surgical procedure, but the other case required prophylactic operation due to malrotation of the small intestine. Although the prognosis of IL largely depends on the severity of associated cardiac anomaly, future bowel obstruction caused by intestinal malrotation may also be life-threatening. In this respect, prenatal diagnosis of IL is important, even when there is no associated cardiac structural anomaly. If IL is suspected in routine fetal ultrasonography, MRI may be recommended to obtain more detailed information on the anatomy of abdominal viscerae, and careful observation for bowel problems is required, especially after oral nutrition is started.

Abnormal laterality and congenital cardiac anomalies. Relations of visceral and cardiac morphologies in the iv/iv mouse

BACKGROUND

In the management of hearts with deranged laterality, it is essential that the left and right atrial chambers are correctly identified. There are two major approaches, which are based on venous connections or on the morphology of the atrial appendages, and there is no consensus as to which is the most useful. We used the iv/iv mouse mutant, which is known to be pertinent to this problem, to evaluate the relations of cardiac defects with atrial, venous, and other visceral morphologies.

METHODS AND RESULTS

The morphology of the heart and other organs was examined in 275 iv/iv mice using criteria based on abnormal laterality in humans. The arrangement of the atrial appendages was determined by morphological examination of the junction between the appendage and the venous component of the atrium. On this basis, 45.1% of cases were shown to have usual atrial arrangement, 50.2% had mirror imagery, 1.5% had right isomerism, and 3.3% had left isomerism. Every case of atrial isomerism had a cardiac lesion; the morphological types were similar to those seen in human cases. Of cases with either usual or mirror-image arrangement of the appendages, 33.2% had abnormal spleens, but only 3.1% had cardiac defects. Similarly, venous abnormalities were much more common (30.1%) than cardiac defects.

CONCLUSIONS

Study results endorse the importance of the morphology of atrial appendages in predicting cardiac abnormalities and point to the marked inconsistency of the arrangement of other organs, including the spleen and the connections of the systemic veins.

Anatomically corrected malposition of great arteries

Four anomalous hearts are described in which the great arteries arise in unusual fashion from their morphologically appropriate ventricles. This malformation, previously termed anatomically corrected transposition, is now termed anatomically corrected malposition. This is because, following the precedent of Van Praagh and his associates, we now reserve the term 'transposition' to describe the situation in which both great arteries arise from separate morphologically inappropriate ventricles. All the hearts examined exhibited atrioventricular concordance, I with viscero-atrial situs inversus, and 3 with situs solitus. However, there were considerable variations in ventricular morphology between the cases. Thus, 2 cases exhibited atresia of the right atrioventricular valve, and in the remaining 2 cases right and levt ventricular sinuses were both identified. Two of the cases also had pulmonary atresia, and coronary artery anomalies were present in all 4. The cases emphasize the fact that the term anatomically corrected malposition describes not a discrete anomaly but only a ventriculo-arterial relation, which is one of ventriculo-arterial concordance. Doubt has previously been cast upon the existence of this as an anatomical entity. It is concluded that the relation does indeed exist, and furthermore can coexist with all varieties of atrioventricular relations. It is suggested that the differing atrioventricular relations can be distinguished by usage of the terms 'concordant' or 'discordant' anatomically corrected malposition. Finally, it is emphasized that it is necessary to distinguish this anomaly, which in most cases presents with left-sided anterior aorta, from the left-sided anterior aorta more frequently encountered in classically corrected transposition'.

Systematization and clinical study of dextroversion, mirror-image dextrocardia, and laevoversion

Images

Systematization and embryological and anatomical study of mirror-image dextrocardias, dextroversions, and laevoversions

Images

Dextrocardia and isolated laevocardia. II. Situs inversus and isolated dextrocardia

Images