Biomedical subjects
Publications and source records attributed to D F Dickinson.
The angiographic and haemodynamic findings in 2 cases of Pompe's disease (glycogenosis type II) indicated an abnormal trabecular pattern, not previously reported, on the left ventricular angiogram of both patients. This feature may be helpful in distinguishing Pompe's disease from other forms of myocardial abnormality.
Two pathological specimens are described in which a bizarre distortion of atrioventricular and ventriculoarterial relations existed. In both cases anterior and leftward displacement of the tricuspid valve coexisted with rightward displacement of the infundibular regions and semilunar valves. Abnormal expansion of the AV canal, possibly secondary to malrotation of the cardiac tube, is considered as a possible cause of the anomaly. One of the hearts showed severe subpulmonary stenosis produced by a valve-like structure which was well differentiated, with a complete annulus and chordae tendineae that inserted in a parachute-like fashion on the infundibular septum. The morphology of this structure was clearly different from that fo the fibrous tags described in other anomalies. Its origin is uncertain. These anomalies have important implications in relation to the nomenclature and classification of congenital heart malformations, and illustrate the value of recent modifications of the segmental approach.
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Three hearts are described in which a fibrous membrane was interposed between the right atrium and a formed but hypoplastic right ventricle, which possessed recognisable inlet, trabecular, and infundibular components. In these hearts the distribution of the conducting tissue was as expected for concordant atrioventricular connections, and contrasts with that seen in the classical type of 'tricuspid atresia'. The distinctive morphological and histological features of these specimens lend further support to our view that the majority of cases of atresia of the right atrioventricular orifice should be regarded as coming within the designation of 'the univentricular heart'.
The cardiac specialized conduction tissue was studied by serial sectioning in 13 cases of situs ambiguus. In four cases of right isomerism, we found paired sinus nodes in relation to a crista terminalis, and in each case a sling of conduction tissue between two atrioventricular nodes was present regardless of the ventricular morphology or cardiac position. In the cases with left isomerism, the sinus node was hypoplastic and abnormally located. We saw two types of atrioventricular conduction systems. In the three cases in which the morphologically right ventricle lay to the right of the morphologically left ventricle (presumed d-loop), a single atrioventricular bundle arose from a normally located atrioventricular node. In the five cases in which the morphologically right ventricle lay to the left of the morphologically left ventricle (presumed l-loop) and in the one case with a univentricular heart, paired atrioventricular nodes were present, linked or potentially linked by a sling of conduction tissue.
22 specimens of univentricular hearts of right ventricular type were examined morphologically. 6 hearts were sectioned for study of the conducting tissue. All the specimens had rudimentary second chambers, which were frequently so small as to have been overlooked, both angiographically and at initial morphological study. The segmental connexions and intracardiac relationships varied widely. Examples were found with 2 atrioventricular valves, a common valve and with absence of either the right or the left atrio-ventricular connexion. In some cases straddling of an atrioventricular valve was observed. The rudimentary chambers always lay posteriorly but varied between a position to the left of the ventricle and one to the right. The septum between ventricle and rudimentary chamber ran to the crux of the heart in all but 2 instances. In most specimens both great arteries arose from the ventricle (double outlet ventricle), so that the rudimentary chamber was solely a trabecular pouch. 4 hearts had concordant arterial connections with the aorta arising from a posterior "outlet" chamber. Pulmonary atresia was found in 5 cases and aortic atresia in 2. The conduction system originated from a normally placed atrioventricular node in 4 out of 6 cases and was related to the trabecular septum in 5. The penetrating bundle usually descended onto the crest of the septum at the "crux" of the heart and bifurcated astride it. In 2 cases with an absent atrioventricular connexion the penetrating bundle originated from an abnormally placed node and in one of these specimens a sling of conducting tissue was identified with dual pathways.
Our experience with the use of a fresh antibiotic sterilized aortic root homograft inlayed into the right ventricular outflow tract is described. With this technique, compression of the graft between the sternum and heart has been avoided and residual right ventricle to distal pulmonary artery pressure gradients have been small. The functional status of the survivors is good over a follow-up period of up to 3 yr. The advantages of this approach compared with a conventionally placed heterograft conduit or an outflow tract gusset are discussed.
One of mono-zygotic twins who had the asplenia syndrome with severe cardiac malformations is described, the other twin being normal. This is the first documented case of situs ambiguus in mono-zygotic twins. The relationship of situs ambiguus to situs inversus, which has previously been described in a number of mono-zygotic twin pairs (some concordant and some discordant) is unclear.