Diane E. Spicer

A simplified categorization for common arterial trunk

OBJECTIVE A common arterial trunk is a solitary trunk that exits the heart through a common ventriculo-arterial junction and supplies directly the systemic, pulmonary, and coronary arterial pathways. It remains to be determined, however, how best to subclassify those hearts fulfilling this definition. The time-honored classification is based on the morphology of the pulmonary arteries, but an alternative approach also places emphasis on the nature of the systemic pathways. We evaluated our experience to establish whether these different approaches can be reconciled. METHODS We examined 28 autopsied hearts with common arterial trunks; the specimens were drawn from the archives of three institutions. Based on our analysis, we simplified classification into hearts with aortic or pulmonary dominance. We used this approach to categorize 42 patients who had undergone surgical correction at Childrens Memorial Hospital in Chicago. RESULTS All autopsied hearts could be assigned to groups with either aortic or pulmonary dominance of the common arterial trunk, with 20 and 8 specimens, respectively, fitting into these categories. Pulmonary dominance was found only when the aortic component of the trunk was hypoplastic and an arterial duct supplied the majority of flow to the descending aorta. Only in this setting did we observe pulmonary arteries arising from the sides of the major pathway, and only in this setting was the aortic component discrete from the pulmonary component within the pericardial cavity. CONCLUSIONS This simple approach to classification reconciles the existing disparate categorizations of patients having common arterial trunks and it emphasizes the principal morphologic determinant of surgical outcome.

The Development of Septation in the Four‐Chambered Heart

The past decades have seen immense progress in the understanding of cardiac development. Appreciation of precise details of cardiac anatomy, however, has yet to be fully translated into the more general understanding of the changing structure of the developing heart, particularly with regard to formation of the septal structures. In this review, using images obtained with episcopic microscopy together with scanning electron microscopy, we show that the newly acquired information concerning the anatomic changes occurring during separation of the cardiac chambers in the mouse is able to provide a basis for understanding the morphogenesis of septal defects in the human heart. It is now established that as part of the changes seen when the heart tube changes from a short linear structure to the looped arrangement presaging formation of the ventricles, new material is added at both its venous and arterial poles. The details of these early changes, however, are beyond the scope of our current review. It is during E10.5 in the mouse that the first anatomic features of septation are seen, with formation of the primary atrial septum. This muscular structure grows toward the cushions formed within the atrioventricular canal, carrying on its leading edge a mesenchymal cap. Its cranial attachment breaks down to form the secondary foramen by the time the mesenchymal cap has used with the atrioventricular endocardial cushions, the latter fusion obliterating the primary foramen. Then the cap, along with a mesenchymal protrusion that grows from the mediastinal mesenchyme, muscularizes to form the base of the definitive atrial septum, the primary septum itself forming the floor of the oval foramen. The cranial margin of the foramen is a fold between the attachments of the pulmonary veins to the left atrium and the roof of the right atrium. The apical muscular ventricular septum develops concomitant with the ballooning of the apical components from the inlet and outlet of the ventricular loop. Its apical part is initially trabeculated. The membranous part of the septum is derived from the rightward margins of the atrioventricular cushions, with the muscularizing proximal outflow cushions fusing with the muscular septum and becoming the subpulmonary infundibulum as the aorta is committed to the left ventricle. Perturbations of these processes explain well the phenotypic variants of deficient atrial and ventricular septation. Anat Rec, 297:1414–1429, 2014.

Ventricular Septal Defect

BackgroundVentricular septal defects are the commonest congenital cardiac malformations. They can exist in isolation, but are also found as integral components of other cardiac anomalies, such as tetralogy of Fallot, double outlet right ventricle, or common arterial trunk. As yet, there is no agreement on how best to classify such defects, nor even on the curved surface that is taken to represent the defect.MethodsBased on our previous pathological and clinical experiences, we have reviewed the history of classification of holes between the ventricles. We proposed that the defects are best defined as representing the area of deficient ventricular septation. This then permits the recognition of clinically significant variants according to the anatomic borders, and the way the curved surface representing the area of deficient septation opens into the morphologically right ventricle.ResultsClinical manifestation depends on the size of the defect, and on the relationship between systemic and pulmonary vascular resistances. Symptoms include failure to thrive, along with the manifestations of the increase in flow of blood to the lungs. Diagnosis can be made by physical examination, but is confirmed by echocardiographic interrogation, which delineates the precise anatomy, and also provides the physiologic information required for optimal clinical decision-making. Cardiac catheterization offers additional information regarding hemodynamics, particularly if there is a concern regarding an increase in pulmonary vascular resistance. Hemodynamic assessment is rarely necessary to make decisions regarding management, although it can be helpful if assessing symptomatic adults with hemodynamically restrictive defects. In infants with defects producing large shunts, surgical closure is now recommended in most instances as soon as symptoms manifest. Only in rare cases is palliative banding of the pulmonary trunk now recommended. Closure with devices inserted on catheters is now the preferred approach for many patients with muscular defects, often using a hybrid procedure. Therapeutic closure should now be anticipated with virtually zero mortality, and with excellent anticipated long-term survival.ConclusionVentricular septal defects are best defined as representing the borders of the area of deficient ventricular septation. An approach on this basis permits recognition of the clinically significant phenotypic variants.

Coronary artery fistula: a review.

Coronary arterial fistulas are abnormal connections between the coronary arteries and the chambers of the heart or major thoracic vessels. Although first described in 1841, the true incidence is difficult to evaluate because approximately half of the cases may be asymptomatic and clinically undetectable. This review will discuss the history and prevalence of coronary artery fistulas and their morphology, histology, presentation, diagnosis, treatment options, and complications.

Revisiting the Anatomy of the Living Heart.

An understanding of the complexity of cardiac anatomy is required by all who seek, in the setting of cardiac disease, to interpret the images confronting them. Although the mysteries of cardiac structure have been extensively addressed, significant gaps continue to exist between the descriptions provided by morphologists and by those working in the clinical setting. In part, this reflects the limitations in providing 3D visualization of such a complicated organ. Current 3D imaging technology now permits visualization of the cardiac components using datasets obtained in the living individual. These advances, furthermore, demonstrate the anatomy in the setting of the heart as imaged within the thorax. It has been failure to describe the heart as it lies within the thorax that remains a major deficiency of many morphologists relying on the dissecting room to provide the gold standard. Describing the heart in attitudinally appropriate fashion, a basic rule of clinical anatomy, creates the necessary bridges between anatomists and clinicians. The rapid progression of cardiac interventional techniques, furthermore, emphasizes the need to revisit cardiac anatomy using a multidisciplinary approach. In this review, therefore, we illustrate the advantages of an attitudinally correct approach to cardiac anatomy. We then focus on the morphology of the arterial roots, revealing the accuracy that can now be achieved by clinicians using datasets obtained during life.

Manifestations of bodily isomerism

We report the findings present in 49 postmortem specimens from patients with so-called heterotaxy, concentrating on those found in the extracardiac systems of organs. Also known as bodily isomerism, we suggest that it is important to segregate the syndromes into their isomeric subtypes to be able to make inferences regarding likely extracardiac and intracardiac findings to allow for proper surveillance. We demonstrate that this is best done on the basis of the atrial appendages, which were isomeric in all the hearts obtained from the specimens available for our inspection. The abdominal organs do not demonstrate isomerism, and they show variable features when compared to the isomeric atrial appendages.

Veno-venous bridges: the forerunners of the sinus venosus defect.

BACKGROUND Differentiation of the so-called sinus venosus defect from other defects permitting shunting between the atrial chambers remains problematic. The lesion is not a true septal defect, and current theories to explain the existence of the sinus venosus defect fall short. The presence of persistent systemic to pulmonary venous connections has been proposed to explain the existence of the sinus venosus defect. METHODS Clinical histories and radiological findings of six patients are reviewed. Three patients have veno-venous bridges, two have partial anomalous pulmonary venous connections, and one patient has a sinus venosus defect. The clinical information is reviewed, along with current developmental and morphological considerations. DISCUSSION We provide radiographic, developmental, and morphological evidence to support the theory that a so-called sinus venosus defect is the consequence of persistence of foetal systemic to pulmonary veno-venous bridges, rather than of deficiencies in atrial septation.

Describing the Cardiac Components—Attitudinally Appropriate Nomenclature

One of the first principles taught to medical students when they begin their study of human anatomy is that all structures within the body should be described as seen in the anatomical position. In this position, the subject is standing upright and facing the observer. The observer then views left-sided structures to the right hand and right-sided structures to the left hand. Those entities closest to the head are said to be superior, while those closest to the feet are considered to be inferior. And structures within the chest adjacent to the sternum are appropriately described as being anterior, with those adjacent to the spine properly being considered to be posterior. These conventions have been obeyed over the centuries for all organs except the heart. For reasons that are not clear, cardiac structures are described as though the heart has been removed from the thorax and positioned on its apex. This leads to unfortunate descriptions, such as the artery coursing through the middle of the diaphragmatic surface of the heart, blockage of which produces inferior infarction, being said to be posterior and descending. In reality, it is inferior and interventricular. The advent of three-dimensional techniques for imaging, such as computed tomography or magnetic resonance imaging, now demonstrates in unequivocal fashion the spurious natures of such descriptions, which extend also to the leaflets and papillary muscles of the atrioventricular valves. It is surely now incumbent on human anatomists and cardiologists to describe structures within the heart as they are seen relative to the thorax, in other words to do no more than follow a basic rule of human anatomy and use attitudinally appropriate terms. Whether clinical cardiologists will adopt such a logical approach is moot, but adoption will surely facilitate understanding for the future generations? This article is part of a JCTR special issue on Cardiac Anatomy.

Fistulous communications with the coronary arteries in the setting of hypoplastic ventricles.

Neonates born with hypoplastic left heart syndrome now have a remarkably improved prognosis compared with the situation existing before the development of the Norwood sequence of operative procedures. Some of those born with hypoplastic right ventricles in the setting of pulmonary atresia with an intact ventricular septum, however, still have a relatively poor prognosis. In part this reflects the presence of fistulous communication between the cavity of the right hypoplastic right ventricle and the coronary arterial tree. Such fistulous communications are now increasingly recognised as being important in the setting of hypoplastic left heart syndrome. In this brief review, we describe the anatomy of the communications. Those found with hypoplastic right ventricles are seen most frequently when the cavity of the ventricle effectively represents only the inlet, this in turn reflecting mural overgrowth of the apical trabecular and outlet components during foetal development. This almost certainly reflects an earlier appearance of the pulmonary valvar lesion that promotes the cavitary hypoplasia. In those with hypoplastic left ventricles, the key feature differentiating those with fistulous communications is the presence of a patent mitral valve, since the left ventricle is typically no more than a virtual slit in postero-inferior ventricular wall in the setting of mitral valvar atresia or absence of the left atrioventricular connection.

Anomalous origin and course of the coronary arteries.

In the normal heart, the right and left coronary arteries arise from the aortic valvar sinuses adjacent to the pulmonary trunk. The right coronary artery then directly enters the right atrioventricular groove, whereas the main stem of the left coronary artery runs a short course before dividing to become the anterior interventricular and circumflex arteries. These arteries can have an anomalous origin from either the aorta or pulmonary trunk; their branches can have various anomalous origins relative to arterial pedicles. Other abnormal situations include myocardial bridging, abnormal communications, solitary coronary arteries, and duplicated arteries. Understanding of these variations is key to determining those anomalous patterns associated with sudden cardiac death. In the most common variant of an anomalous origin from the pulmonary trunk, the main stem of the left coronary artery arises from the sinus of the pulmonary trunk adjacent to the anticipated left coronary arterial aortic sinus. The artery can, however, arise from a pulmonary artery, or the right coronary artery can have an anomalous pulmonary origin. The key feature in the anomalous aortic origin is the potential for squeezing of the artery, produced by either the so-called intramural origin from the aorta, or the passage of the abnormal artery between the aortic root and the subpulmonary infundibulum.