Surgical anatomy of the coronary circulation in hearts with discordant atrioventricular connections.

We examined the arrangement of the coronary arterial and cardiac venous systems in 46 specimens with discordant atrioventricular connections so as to identify any structural abnormalities and to consider their surgical implications in terms of anatomical biventricular repair. Grossly abnormal arterial courses were seen in 11 hearts (24%). A substantial branch supplying the morphologically right ventricular outflow tract, which could restrict a ventriculotomy, was found in 61% of cases. The coronary sinus received all the morphologically right ventricular veins, as well as the posterior interventricular vein, in 40 hearts, this pattern being in contrast to the pattern in the normal heart. The morphologically left ventricular and anterior interventricular veins, all of which drain via the coronary sinus in the normal heart, were frequently connected independently to the morphologically right atrium in the specimens with discordant connections, the drainage occurring through the spaces between the pectinate muscles. These direct drainages are at risk of potential damage either by extensive intra-atrial maneuvers or by postoperative intraatrial thrombosis. It is predicted, therefore, that surgical results can be improved still further when account is taken of this vascular anatomy of the heart itself.

Atrial appendages and venoatrial connections in hearts from patients with visceral heterotaxy.

BACKGROUND: Venoatrial connections are important when choosing surgical options for patients with visceral heterotaxy. The precise morphology of the atriums, however, is often obfuscated by the term "visceral heterotaxy." This morphologic study aims to clarify the features of significance to the cardiac surgeon. METHODS: We investigated 183 hearts from patients known from postmortem inspection to have so-called visceral heterotaxy. The connections of the systemic and pulmonary veins to the atriums, and the detailed morphology of the atriums, were examined in each case. RESULTS: Pectinate muscles extended bilaterally to the crux in 125 hearts determined to have isomeric morphologically right appendages. The other 58 hearts all exhibited bilaterally smooth-walled vestibules, and were diagnosed as having isomeric left appendages. Bilateral superior caval veins were frequent in both groups. The inferior caval vein was right- or left-sided with equal frequency in both groups, but was interrupted only in hearts with isomeric left appendages. The pulmonary veins connected in extraatrial fashion in 48% of cases with isomeric right appendages, whereas, most commonly, pulmonary veins were connected bilaterally to the atriums in those with isomeric left appendages (60%). CONCLUSIONS: Both the morphology of the atrial appendages and the venoatrial connections need to be distinguished to establish precise diagnoses in patients with so-called visceral heterotaxy ("splenic syndromes").

The surgical anatomy of coronary venous return in hearts with isomeric atrial appendages.

Although absence of the coronary sinus is widely recognized in hearts with isomerism of the right atrial appendages, little attention has been paid to the fashion of the venous return from the heart itself. In this study, the arrangement of coronary venous return was investigated in 99 specimens with isomeric right and 49 with isomeric left appendages. In the normal heart, the coronary veins consist of a circumflex component within the atrioventricular groove and longitudinal components on the ventricular mass. The circumflex venous system was seen in 44 hearts with isomerism of left appendages (90%), but 23 of these hearts lacked the anatomic features of the coronary sinus. Circumflex veins were entirely lacking in the other 10% of hearts with isomeric left appendages and in all those with isomeric right appendages. In these hearts, longitudinal veins drained independently into the atria in three patterns. The first was a direct connection, with the venous orifice opening between the trabeculations of the atrial wall immediately having crossed the atrioventricular groove. The second was a crooked return, with the vein running an intramural course along the atrioventricular groove. The third was a distant connection, reaching superiorly to the smooth-walled atrial component after running an intramural course. Intramural courses were seen in 19% of the longitudinal veins, such veins being found in 62% of all hearts with no circumflex venous system. These findings, which to the best of our knowledge have never previously been recognized in detail, almost certainly have potential surgical significance.

Left ventricular structures in atrioventricular septal defect associated with isomerism of atrial appendages compared with similar features with usual atrial arrangement.

In patients with isomeric atrial appendages, regurgitation of atrioventricular valves is recognized clinically as one of the risk factors that militate against successful achievement of definitive repairs. To determine whether this reflected anatomic features, we investigated 91 specimens with atrioventricular septal defect that had a common atrioventricular valve and biventricular atrioventricular connections. Of these specimens, 35 had isomeric right appendages, 23 showed isomeric left appendages, and 33 had usual atrial arrangement. We measured either the size or location of the supporting papillary muscles and the circumference of the mural leaflet within the morphologically systemic ventricle, as well as the length of outlet, inlet, and so-called scooped dimensions of the muscular ventricular septum. Presence of a solitary papillary muscle, or deviation of the attachments of the papillary muscles, was more frequent in hearts with isomeric right appendages. Values for the diameter and lengths of the papillary muscles were significantly smaller in hearts with isomeric right appendages compared with those with usual atrial arrangement (p < 0.001), as were the distances between the papillary muscles (p < 0.002) and the circumference of the mural leaflet (p < 0.001). The proportional length of ventricular outlet was longer in the setting of isomeric right appendages than in the other groups (p < 0.001), whereas the extent of septal scooping showed no differences among these three groups. We conclude that these structural features could be factors in the known insufficiency of the common atrioventricular valve and the ventricular dysfunction in patients with isomeric right appendages.

The myth of the aortic annulus: the anatomy of the subaortic outflow tract.

Surgical repair of the small aortic root is limited in part by the very structure of the outflow tract from the left ventricle. The root is not constructed on the basis of a ringlike annulus supporting the leaflets of the aortic valve. The only truly circular structure within the outflow tract is the junction of the aortic wall with the underlying ventricular structures, themselves partly muscular and partly fibrous. This circular ventriculoarterial junction is crossed by the semilunar attachments of the leaflets of the aortic valve, producing an interlinking arrangement between the expanded aortic sinuses and three triangles of fibrous tissue placed beneath the apexes of the commissures between the valve leaflets. The triangles form extensions of the left ventricle that are related, in part, to the pericardial cavity surrounding the heart. The arrangements of the attachment of the leaflets in malformed valves with two (or only one) effective leaflets are highly abnormal, although these valves are usually produced on the template of three aortic sinuses. The valve with two leaflets rarely gives problems during childhood. In valves producing "critical stenosis", there is usually only one effective leaflet, a condition due to incomplete liberation of two of the anticipated three commissures. Detailed study shows that, in these malformed hearts, the attachment of the leaflets is much more annular than in normal valves, with inadequate formation of the fibrous triangles.

The surgical anatomy of tetralogy of Fallot with pulmonary atresia rather than pulmonary stenosis.

We examined the pertinent surgical features of the anatomy of 56 hearts having tetralogy of Fallot with pulmonary atresia instead of stenosis, or malformations with pulmonary atresia closely related to tetralogy. We took particular cognizance of the pulmonary arterial supply in 15 hearts in which this was derived through systemic-to-pulmonary collateral arteries, dissecting, as far as possible, the bronchopulmonary segmental distribution of the collateral arteries compared to the intrapericardial pulmonary arteries in 11 of these hearts. Two of the hearts had absence of intrapericardial pulmonary arteries, so that a solitary arterial trunk left the base of the heart. Evidence of an atretic subpulmonary infundibulum was found in 40 of the hearts, while such an infundibulum was lacking in the remainder. The pulmonary atresia was muscular in 43 hearts, valvar in 11, while the pulmonary trunk was absent in the other two hearts. In the hearts with collateral arteries, on average 2.6 collaterals were found in each case, varying from two to five per case. Only one of these arose from a brachiocephalic artery, the others all arising from the descending aorta. The distribution of collateral arteries in two cases was remarkably reminiscent of the arrangement of bronchial arteries. As far as could be judged, 16.5 bronchopulmonary segments on average were supplied in each heart, 5.1 exclusively by collateral arteries, 11.8 by intrapericardial pulmonary arteries and an average of 0.64 segments per case having a shared supply.

Anomalies of the left atrioventricular valve and related ventricular septal morphology in atrioventricular septal defects.

A characteristic feature of atrioventricular septal defects is a deficiency of the inlet part of the ventricular septum that results in a "scooped out" appearance. The depth of the scoop in relation to the disposition of the atrioventricular valves has been debated. To clarify the relation between the morphology of the ventricular septum and the disposition of the atrioventricular valves, we quantified these anatomic features in 151 hearts at autopsy to determine whether those features identified particular groups within the overall lesion. We found that 137 hearts had left atrioventricular valves with three leaflets. The left valve in the other 14 hearts exhibited a dual orifice, a two-leaflet or one-leaflet arrangement, or was imperforate. These anomalies could be analyzed in terms of a sequence of diminishing formation of the commissures. Also, three-leaflet valves displayed a variability in which the angular size of the mural leaflet correlated negatively with that of the inferior leaflet. In some of the hearts with a common atrioventricular orifice, the bridging leaflets did not meet over the ventricular septum, thus creating a "gap." The mural leaflet's angular size corresponded to a deficiency of the combined inferior-mural leaflet complex. Hearts with an abnormal disposition of the left atrioventricular valve had the ventricular septum "scooped" to a greater extent than those with a common orifice, although most had separate right and left atrioventricular orifices.

The morphology of the normal aortic valve as compared with the aortic valve having two leaflets.

We studied 30 normal aortic valves and 64 aortic valves with only two leaflets to examine their morphologic components. The components of the aortic valve are the leaflets, the sinuses, and the interleaflet triangles. The first part of our study shows the relationship of these component parts of the normal aortic valve to the other cardiac structures. The second part shows a wide variation in the architecture of valves having two leaflets. Having produced criteria for the number of sinuses and the number of leaflets, we discovered that previous criteria used in the definition of valves with two leaflets are inadequate when the whole valvular complex is considered. Only seven valves in the study have two leaflets supported by two sinuses. The evidence points to the other valves having started with three leaflets but becoming bicuspid during either intrauterine or postnatal life.

Studies on the nature of fibrillar nuclei. Distinction from viral nucleocapsid.

Despite sufficient evidence to the contrary, fibrillar nuclei continue to be claimed by some to represent paramyxovirus. In a review of the electron-microscopic material, fibrillar nuclei were found in a variety of tissues and situations where a viral etiology is unlikely. Fibrillar nuclei were most often found in postmortem and formalin-fixed material. These nuclei were also experimentally produced in postmortem human lung with formalin fixation followed by a deionized water rinse. It is concluded that fibrillar nuclei do not represent virus, but chromatin, and it is believed that this chromatin appearance is related to cell injury and to tissue processing. It is also believed that fibrillar nuclei occur with much greater frequency than realized. These nuclei are usually ignored during examination of specimens by light and electron microscopy because these specimens are usually being selectively screened for other changes and perhaps because a clear understanding of their significance is still lacking.