[Coronary vessel anomalies and persisting myocardial sinusoids in pulmonary atresia with intact ventricular septum]

Assessing the borderline ventricle in a term infant: combining imaging and physiology to establish the right course

PURPOSE OF REVIEW

The purpose of this review is to describe the challenges associated with the diagnosis and treatment of children with borderline ventricles. A borderline ventricle is one in which there is concern that it will not be able to support its circulation. If a biventricular repair is attempted and fails, outcome is often poor. Thus, this early decision is important.

RECENT FINDINGS

For the borderline right ventricle, options to add an additional source of pulmonary blood flow make the surgical strategy a bit more flexible than for patients with a borderline left ventricle. In general, outcome for a so-called one and one-half ventricle repair are generally good, though the long-term outcome and the effects of this physiology on lifelong exercise performance and quality of life remain to be seen. For the small left ventricle, often multiple surgeries are required to 'force' blood into the left ventricle and potentially help it grow. Though this strategy is successful in some, in others it results in significant residual cardiac issues including pulmonary hypertension.

SUMMARY

Determining whether a patient will be better off in the long term with a marginal biventricular repair versus a Fontan circulation remains one of the most difficult problems in the field of pediatric cardiology and cardiac surgery.

Coronary anomalies: incidence and importance

Most patients with coronary anomalies are asymptomatic. The knowledge of those variations could be important in regard to invasive catheter treatment or bypass surgery. In a retrospective study, the angiographic findings based on 4,016 patients (1985-1989) were analyzed concerning coronary anomalies and malformations. Of the patients studied, 39 (0.97%) had coronary anomalies, and in 26 of these patients it was an anomalous circumflex branch. In 14 cases, the circumflex branch arose from a separate origin in the left aortic sinus. In 11 patients the origin was from the proximal segment of the right coronary artery. A singular coronary artery was found in five patients, originating from the right aortic sinus in two patients and from the left aortic sinus in three patients. An origin of the left coronary artery from the pulmonary artery, a coronary fistula, or an origin of the left anterior descending coronary artery from the RCA could be found in only one patient. Unexpected findings during invasive procedures would suggest a possibly existing coronary anomaly, especially when main branches cannot be opacified by selective contrast medium injection.

Myocardial dysgenesis with persistent sinusoids in a neonate with Noonan's phenotype

Structural cardiac anomalies indicative of primary myocardial maldevelopment are reported in a newborn girl with congenital heart block. The cardiac findings included disordered trabeculation of both ventricles with persistent intramyocardial sinusoids, hypoplastic papillary muscles, and dysplastic atrioventricular valves with partial downward displacement of the septal leaflet of the tricuspid valve. Dilatation of the ascending aorta and craniofacial dysmorphism including webbed neck, hypertelorism, and low-set ears raise the possibility of Noonan syndrome.

Coronary and endocardial fibroelastosis of the ventricles in the hypoplastic left and right heart syndromes

In an autopsy material of 29 cases of the hypoplastic left heart syndrome coronary fibroelastosis was found in 1 case, endocardial fibroelastosis in 8 cases. Figures for 10 cases of the hypoplastic right heart syndrome were 6 cases of coronary fibroelastosis and 1 case of endocardial fibroelastosis. Age ranged from stillborn up to 11-1/2 months. Coronary and endocardial fibroelastosis seemed to be mutually exclusive localizations of congenital fibroelastosis since in our material they did not occur together in the same hearts. In hypoplastic right hearts coronary fibroelastosis was either restricted to the right coronary artery (right circumflex and posterior interventricular branch), or it was found also in the left coronary artery (anterior interventricular branch), with the most serve affections always being situated in the right one. In the only case of coronary fibroelastosis among the hypoplastic left hearts the condition was limited to the anterior interventricular branch of the left coronary artery which communicated with the hypoplastic left ventricle by a fistula. Coronary fibroelastosis was exclusively found in branches supplying the hypoplastic right ventricle and/or in a branch connected by a fistula to the hypoplastic left or right ventricle. Endocardial fibroelastosis was generally found in hypoplastic left ventricles with either no outflow or with severe outflow obstruction. A theory concerning the aetiology of both coronary and endocardial fibroelastosis of the hypoplastic ventricles is proposed. It is argued that development of fibroelastosis may in both localizations be caused or favoured by the coincidence of two factors: abnormal haemodynamic conditions and poor oxygenation of blood and tissues. Observations made in a reference material of 35 hypoplastic left and 24 hypoplastic right hearts were in accordance with this view.

Relations between development of the capillary wall and myoarchitecture of the rat heart

The type of the blood supply to the myocardium appears to be closely related to its structural arrangement. The heart of adult poikilotherm animals is either entirely spongious, supplied from the ventricular cavity or its spongious musculature is covered by an outer compact layer with vascular supply. The size of the compact layer increases with increasing heart weight. The changes in the heart size during the ontogenetic development of honoiotherms are accompanied by the gradual transformation of the vascularless spongious musculature into a compact myocardium supplied thrugh coronary vessels. Up to the development of coronary arteries (in the rat up to the 17th day of embryonic life - ed) the myocardium is entirely spongious and supplied from mentricular cavity. Two types of primitive vascular bed are characteristic for this period: a) intertrabecular spaces, which penetrate deep into the ventricular wall as direct continuation of the endocardium, and b) intramyocardial clefts without endothelial lining. During further development of the terminal mascular bed, the outgrowth of endothelial cells into the myocardial clefts is important. The first capillaries with closed endothelial wall can be observed on the 18th ed. At this time various developmental stages o the terminal blood bed can be observed simultaneously. Within the following period (20-21 ed) the thick capillary walls become narrow and pericytes occur. The process of differentiation spreads in both ventricles and in septum from the base to the cardiac apex and is practically finished by the 14th day of postnatal life. The longitudinal orientations of myofibres starts between the 20th and 22nd ed. The final arrangement of muscle cells and capillaries into three layers (outer and inner longitudinal, central circular) is terminated during the second postnatal week.