Siew Yen Ho

Architecture of the pulmonary veins: relevance to radiofrequency ablation

BACKGROUND Radiofrequency ablation of tissues in pulmonary veins can eliminate paroxysmal atrial fibrillation. OBJECTIVE To explore the characteristics of normal pulmonary veins so as to provide more information relevant to radiofrequency ablation. METHODS 20 structurally normal heart specimens were examined grossly. Histological sections were made from 65 pulmonary veins. RESULTS The longest myocardial sleeves were found in the superior veins. The sleeves were thickest at the venoatrial junction in the left superior pulmonary veins. For the superior veins, the sleeves were thickest along the inferior walls and thinnest superiorly. The sleeves were composed mainly of circularly or spirally oriented bundles of myocytes with additional bundles that were longitudinally or obliquely oriented, sometimes forming mesh-like arrangements. Fibrotic changes estimated at between 5% and 70% across three transverse sections were seen in 17 veins that were from individuals aged 30 to 72 years. CONCLUSIONS The myocardial architecture in normal pulmonary veins is highly variable. The complex arrangement, stretch, and increase in fibrosis may produce greater non-uniform anisotropic properties.

Analysis of atrioventricular junction, ventricular mass, and ventriculoarterial junction in 43 specimens with atrial isomerism.

We have analysed the atrioventricular junction, ventricular mass, and ventriculoarterial junction in 43 hearts with isomeric atrial chambers. Of the hearts, 32 had atrial chambers of bilateral right morphology while 11 had atrial chambers with bilateral left atrial characteristics. Among the hearts with right atrial isomerism, there were 13 biventricular hearts, all with ambiguous atrioventricular connection. Eight had a common valve and five had two atrioventricular valves. In the other 19 hearts, the atrial chambers were connected to only one ventricular chamber, 18 having double inlet ventricle through a common valve and the other having absence of the left atrioventricular connection. In these univentricular hearts, all possible types of ventricular morphology were found. The ventriculoarterial junction among these hearts with right isomerism showed great variation. In the hearts with left atrial isomerism, nine hearts had two ventricles and two were univentricular. The biventricular hearts all had ambiguous atrioventricular connection, six via a common valve and three via two valves. The two univentricular hearts both had double inlet via a common valve, one to a chamber of right ventricular type and the other to a chamber of left ventricular type. Both had rudimentary chambers of complementary pattern. The ventriculoarterial junction again showed much variation. Statistical analysis showed that pulmonary obstruction and a univentricular heart were both significantly more frequent in association with right compared with left isomerism. Significant differences were also noted in the two groups in terms of ventriculoarterial connections and infundibular morphology.

Endocardial fibroelastosis and hypoplasia of the left ventricle in neonates without significant aortic stenosis.

Endocardial fibroelastosis in neonates with hypoplasia of the left ventricle is usually associated with severe aortic stenosis or atresia. In this study three hearts were examined, in which severe hypoplasia of the left ventricular cavity with myocardial hypertrophy and endocardial fibroelastosis were associated with small but non-stenotic subaortic outflow tracts and aortic valves. These features were contrasted with those of neonatal left heart hypoplasia in aortic stenosis and atresia. The index cases were examples of the very rare contracted form of endocardial fibroelastosis.

Cross sectional echocardiographic assessment of the extent of the atrial septum relative to the atrioventricular junction in atrioventricular septal defect

Objective To study patients with atrioventricular septal defect to determine the pathognomonic morphological features of the lesion and the relation between the septal structures and the atrioventricular junction. Setting Tertiary level paediatric cardiology centre. Methods Cross sectional echocardiograms from 60 patients were reviewed using qualitative and quantitative analysis. The unifying feature was the presence of a common atrioventricular junction. The overall dimensions of the septal defect were determined and related to the plane of the common junction; the extent of both the atrial and the ventricular septal components was then measured according to the site of closure of the bridging leaflets. Results In 48 cases, the common junction was guarded by a common valvar orifice, but in 12 cases there were separate right and left valvar orifices. Irrespective of the valvar morphology, no significant difference was found between the groups in terms of the dimensions of the atrial and ventricular septal components. In all patients, the hole permitting shunting at atrial level extended below the plane of the atrioventricular junction, with a variable position of the leading edge of the atrial septum itself. Conclusions The atrioventricular junction is a common structure irrespective of valvar morphology. In spite of the presence of unequivocal shunting at atrial level, the atrial septum is usually a well formed structure, even extending in some below the level of the common atrioventricular junction.

Straddling atrioventricular valve with absent atrioventricular connection. Report of 10 cases.

From the Department ofPaediatrics and Surgery, Cardiothoracic Institute, Brompton Hospital, Fulham Road, London; Thoracic Unit, The Hospitalfor Sick Children, London; Freeman Road Hospital, Newcastle-upon-Tyne; Department ofPathology, University ofAmsterdam, Holland; Department ofAnatomy, State University ofLeiden, Holland; Department ofPathology, Grimsby General Hospital, South Humberside; and Institute of Child Health, University of Liverpool

The Pathology of Univentricular Atrioventricular Connection

Lesions described according to the presumed singularity of their ventricular mass create problems in nomenclature and understanding. Included are hearts with double-inlet ventricle and those with atrioventricular valve atresia. In recent years, along with various colleagues [1–3], we have argued that all hearts with double-inlet should be considered (in terms of ventricular morphology) along with those having the type of atrioventricular valve atresia, which is characterized by absence of one atrioventricular connection. Critics said that our anatomic concept was flawed, because we used double-inlet atrioventricular connection as our unifying hallmark. In fact, the morphologic concept we promoted was entirely accurate. The confusion related to our illogical and meaningless use of the adjective “univentricular” (or “single”) to describe the ventricular mass in hearts that obviously possessed two ventricles. The resolution of this problem is simple and effective: to apply the adjective “univentricular” to the appropriate feature it describes—namely, the atrioventricular connection.