Interatrial communication through the mouth of the coronary sinus

Unroofed Coronary Sinus as Potential Cause of Ischemic Stroke Following Left Atrial Appendage Closure

Unroofed coronary sinus is a rare type of atrial septal defect with a strong association with persistent left superior vena cava. We describe a case with unroofed coronary sinus and persistent left superior vena cava as a cause of recurrent embolic strokes following left atrial appendage closure for atrial fibrillation. (Level of Difficulty: Advanced.).

Is it really a levoatrial cardinal vein?

With the advent of computed tomographic interrogation, it is increasingly frequent to find venous channels that provide direct connections between the pulmonary and systemic veins. These channels, before the introduction of three-dimensional techniques for clinical imaging, were usually found providing an "overflow" for the obstructed left atrium in settings such as hypoplastic left heart syndrome, or divided left atrium. Similar channels, however, had been described almost 100 years ago, with one accurately described as a jugulo-pulmonary vein. Nowadays, however, it is much more usual to find the channels described as levoatrial cardinal veins, even though it is recognized that they are not "levo," often not "atrial," and for sure not "cardinal." In this review, we assemble the evidence supporting the notion that they are better considered as pulmonary-to-systemic collateral channels. We emphasize their similarity, in terms of development, to the sinus venosus and coronary sinus defects.

Persistent left superior caval vein draining into right atrium, but not through the coronary sinus

Persistence of the left superior caval vein is the most commonly reported thoracic venous anomaly. The vein usually drains into the right atrium through the coronary sinus, reflecting its developmental origin. We describe an unusual variant, in which the vein drained directly into the right atrium.

Wide unroofed coronary sinus and cryptogenic stroke: a case report

Background 

Unroofed coronary sinus (UCS) is a rare congenital cardiac anomaly in which there is complete or partial absence of the roof of the coronary sinus (CS) resulting in a communication between the right and left atria. There are four types of UCS described in the literature. While usually asymptomatic and discovered incidentally on imaging, UCS can be the source of a brain abscess or paradoxical embolism.

Case summary 

A 62-year-old gentleman presented to the emergency department with sudden onset of right-sided weakness and subsequent unresponsiveness. His brain computed tomography (CT) was consistent with left-sided stroke. Transthoracic echocardiography was remarkable for a dilated CS and an agitated saline study was suggestive of an UCS. A gated cardiac CT with coronary angiography confirmed a wide communication between the CS and left atrium. Right heart catheterization did not show evidence of left to right shunt. He had no abnormal rhythm on telemetry monitoring throughout his hospital stay.

Discussion 

Unroofed coronary sinus is the least prevalent form of an atrial septal defect. Unroofed coronary sinus is usually asymptomatic and is diagnosed incidentally in imaging studies, however, it should be suspected in patients with cerebral emboli or evidence of left to right shunt with unexplained arterial desaturation. Transthoracic echocardiography is the most widely used imaging modality for the diagnosis of UCS but is limited in its ability to visualize the posterior cardiac structures such as the CS and pulmonary veins. Gated cardiac CT is a great diagnostic tool for UCS.

Unroofed coronary sinus: An unusual interatrial communication and a rare childhood entity

Unroofed coronary sinus, an unusual form of interatrial communication, is a rare cardiac anomaly. It is not a true defect of the atrial septum. It is described as a partial (focal or fenestrated) or complete absence of the roof of the coronary sinus, resulting in a communication between the coronary sinus and left atrium. It is presumably the least common variety of defects associated with interatrial shunting. Such defects are often difficult to diagnose and may even be overlooked during surgery for complex congenital heart disease. In most cases, they are associated with a persistent left superior vena cava, pulmonary or tricuspid atresia, and hearts with isomeric right atrial appendages. We report a case of this unusual form of interatrial communication without any associated anomalies in a 7-year-old girl child who presented to us with exertional dyspnea.

Anatomy of the normal fetal heart: The basis for understanding fetal echocardiography

The rapid changes that have taken place in recent years in relation to techniques used to image the fetal heart have emphasized the need to have a detailed knowledge ofnormal cardiac anatomy. Without such knowledge, it is difficult, if not impossible, to recognize the multiple facets of congenital cardiac disease. From the inception of fetal echocardiographic screening, the importance of basic knowledge of cardiac anatomy has been well recognized. The current machines used for imaging, however, now make it possible potentially to recognize features not appreciated at the start of the specialty. So as to match the advances made in imaging, we have now revisited our understanding of normal cardiac anatomy in the mid-gestational fetus. This was made possible by our dissection of 10 fetal hearts, followed by production of addition histological sections that mimic the standard ultrasound views. The fetuses ranged in gestational age from between 20 and 28 weeks. We then correlated the obtained anatomic images with the corresponding ultrasonic images used in the standard fetal screening scan. We also interrogated the anatomic sections so as to clarify ongoing controversies regarding detailed features of the normal cardiac anatomy. We have been able to show that the views now obtained using current technology reveal many details of anatomy not always appreciated at earlier times. Knowledge of these features should now permit diagnosis of most congenital cardiac malformations. The anatomic-echocardiographic correlations additionally provide a valuable resource for both the understanding and teaching of fetal echocardiography.

Unroofed Coronary Sinus Syndrome: An Easily Corrected Congenital Anomaly But More Diagnostic Suspicion Is Needed

BACKGROUND

Unroofed coronary sinus syndrome (URCSS) is a spectrum of cardiac anomalies in which part (partial type) or the entire common wall (complete type) between the coronary sinus (CS) and left atrium is absent. It is commonly associated with a persistent left superior vena cava (PLSVC). The PLSVC can even anomalously connect to the left atrium in complete type anomaly. URCSS has been reported to be associated with delayed diagnosis and life-threatening cerebral injury. The purpose of the present study was to review our experience with surgical correction of this often-concealed malformation and discuss methods for reducing diagnostic omission.

METHODS

Thirty-six patients with URCSS who underwent surgical treatment from 1998 to 2015 in our institution were enrolled in this retrospective analysis.

RESULTS

The mean age of the patients was 21.8±20.9 years. Type I anomalies were found in 15 (41.7%) patients, type II in 4 (11.1%), type III in 6 (16.7%), and type IV in 11 (30.6%). A patient presenting with URCSS without other defects was identified in six (16.7%). One patient (2.8%) had a history of paradoxical embolisation. Twenty-five patients (69.4%) were diagnosed before surgery. Ten patients (27.8%) were diagnosed with URCSS intraoperatively. One patient (2.8%) was diagnosed with URCSS by follow-up echocardiography after device occlusion for atrial septal defect. Coronary sinus ostium dilation was the most important clue leading to partial type lesion disclosure intraoperatively. The anomalous PLSVC of 15 patients was repaired using roof tunnel technique in four (26.7%) cases, baffle redirection in eight (53.3%) cases, posterior left atrial wall plicating in two (13.3%) cases, and extracardiac bypass in one (6.7%) case. Postoperative complete atrioventricular block occurred in one patient (2.8%). One patient died postoperatively (2.8%). All patients are doing well after discharge from hospital.

CONCLUSIONS

Diagnostic suspicion can contribute to lesion disclosure. Surgical correction has good long-term outcomes and low risks.

Insights regarding the normal and abnormal formation of the atrial and ventricular septal structures

Knowledge of cardiac development can provide the basis for understanding the morphogenesis of congenital cardiac malformations. Only recently, however, has the quality of information regarding cardiac embryology been sufficient to justify this approach. In this review, we show how such knowledge of development of the normal atrial and ventricular septal structures underscores the interpretation of the lesions that provide the basis for interatrial and interventricular shunting of blood. We show that current concepts of atrial septation, which frequently depend on a suggested formation of an extensive secondary septum, are simplistic. There are additional contributions beyond growth of the primary septum, but the new tissue is added to form the ventral buttress of the definitive atrial septum, rather than its cranial margin, as is usually depicted. We show that the ventricular septum possesses muscular and membranous components, with the entirety of the muscular septum produced concomitant with the so-called ballooning of the apical ventricular component. It is expansion of the atrioventricular canal that creates the inlet of the right ventricle, with no separate formation of an "inlet" septum. The proximal parts of the outflow cushions initially form a septal structure between the developing ventricular outlets, but this becomes converted into the free-standing muscular subpulmonary infundibulum as the aortic outlet is transferred to the left ventricle. These features of normal development are then shown to provide the basis for understanding of the channels that provide the means for interatrial and interventricular shunting.

Exercises in anatomy: the normal heart

In this series of videoclips, we analyze the anatomy of the normal heart. We begin our overview by emphasizing the need, in the current era, to describe the heart in attitudinally appropriate fashion. Increasingly, clinicians are demonstrating the features of the heart as it is located within the body. It is no longer satisfactory, therefore, to describe these components in a ‘Valentine’ fashion, as continues to be the case in most textbooks of normal or cardiac anatomy. We then emphasize the importance of the so-called morphological method, which states that structures within the heart should be defined on the basis of their own intrinsic morphology, and not according to other parts, which are themselves variable. We continue by using this concept to show how the appendages serve to distinguish between the atrial chambers, while the apical trabecular components provide the features to distinguish the ventricles. We then return to the cardiac chambers, emphasizing features of surgical significance, in particular the locations of the cardiac conduction tissues. We proceed by examining the cardiac valves, and conclude by providing a detailed analysis of the septal structures.

Total anomalous pulmonary venous connection to the unroofed coronary sinus in a neonate

This report describes the unique case of a newborn with total anomalous pulmonary venous connection to an unroofed coronary sinus associated with Ullrich-Turner syndrome and aortic coarctation. Total anomalous pulmonary venous connection to the unroofed coronary sinus is an extremely uncommon cardiac abnormality. This congenital heart disease is difficult to diagnose and rarely ever reported. Few symptoms are to be expected when it is not associated with other congenital heart defects. This lesion results in a "naturally" corrected total anomalous pulmonary venous return and a coronary sinus atrial septal defect presenting as a left-to-right shunting lesion. Making the diagnosis of this cardiac defect, and if possible, surgical repair is of importance because cardiac dysfunction due to significant atrial left-to-right shunting is a known long-term complication in the older adult patient.

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.

Cortriatriatum With Classical Raghib Complex

Cortriatriatum with Raghib’s complex is a rarely reported entity. An 18-month-old baby who presented with tachypnea and cyanosis was diagnosed to have cortriatriatum sinistrum along with a persistant left superior caval vein draining to the left atrium through an unroofed coronary sinus. The child underwent successful surgical correction with excision of the cortriatriatum and baffling of the left superior caval vein to the right atrium.

Sonographic markers for early diagnosis of fetal malformations

Fetal malformations are very frequent in industrialized countries. Although advanced maternal age may affect pregnancy outcome adversely, 80%-90% of fetal malformations occur in the absence of a specific risk factor for parents. The only effective approach for prenatal screening is currently represented by an ultrasound scan. However, ultrasound methods present two important limitations: the substantial absence of quantitative parameters and the dependence on the sonographer experience. In recent years, together with the improvement in transducer technology, quantitative and objective sonographic markers highly predictive of fetal malformations have been developed. These markers can be detected at early gestation (11-14 wk) and generally are not pathological in themselves but have an increased incidence in abnormal fetuses. Thus, prenatal ultrasonography during the second trimester of gestation provides a “genetic sonogram”, including, for instance, nuchal translucency, short humeral length, echogenic bowel, echogenic intracardiac focus and choroid plexus cyst, that is used to identify morphological features of fetal Down’s syndrome with a potential sensitivity of more than 90%. Other specific and sensitive markers can be seen in the case of cardiac defects and skeletal anomalies. In the future, sonographic markers could limit even more the use of invasive and dangerous techniques of prenatal diagnosis (amniocentesis, etc.).

Unroofed Coronary Sinus Presenting as Cerebral Abscess: A Case Report

A sixty eight year-old woman with a long-standing history of hypertension, dizziness and a history of congenital heart disease presented with speech difficulties and disorientation. She was diagnosed with a brain abscess, confirmed by a stereotactic biopsy. Transthoracic echocardiographic evaluation revealed a persistent left superior vena cava (PLSVC) with an unroofed coronary sinus (URCS) along with a small secundum atrial septal defect. Her heart catheterization showed a partially unroofed coronary sinus along with a bidirectional shunt. She was referred for surgical closure of her unroofed coronary sinus and the secundum atrial septal defect. Her brain abscess responded well to antibiotic treatment. While waiting for open-heart surgery, she suffered from an acute myocardial infarction and underwent emergent percutaneous coronary intervention to the right coronary artery. Subsequently, she underwent elective surgical repair of the unroofed coronary sinus, along with closure of the atrial septal defect. When she was seen in follow-up she reported a complete resolution of her dizziness and felt more energetic. Unroofed coronary sinus syndrome (URCS) is a rare congenital cardiac anomaly in which there is a communication between the coronary sinus and the left atrium. While non-invasive imaging with echocardiography, MRI or CT is helpful in making the diagnosis, cardiac catheterization remains integral in the evaluation and management planning. Management is guided by the presence of clinical symptoms with consideration of repair when patients become symptomatic. Prognosis after surgery is excellent, recently transcatheter based treatment therapies are becoming more frequent. We present a rare case of URCS with PLSVC presenting as a cerebral abscess in late adulthood. She had bidirectional shunting manifesting as a cerebral abscess. She responded well to the corrective surgery and was doing well on follow up.

Persistent left superior vena cava: does it have a role in the pathogenesis of hypoplastic left heart syndrome?

The coexistence of a persistent left superior vena cava (PLSVC) and congenital anomalies, both cardiac and noncardiac, is well documented, but whether PLSVC contributes to the development of cardiac malformations is controversial. We conducted a retrospective review of perinatal and pediatric autopsies to determine the association between PLSVC and other congenital anomalies. Of 362 patients, 91 (25%) had congenital heart disease and 19 (5.2%) had PLSVC. Eight cases (47%) were associated with specific syndromes, including heterotaxy syndrome, trisomy 18, trisomy 13, and Jacobsen syndrome. Seventeen cases of PLSVC (89%) were associated with congenital heart disease, most of which were complex. Isolated PLSVC was found in 2 cases (11%). Eight of the 19 PLSVC cases (47%) were associated with hypoplastic left heart syndrome (HLHS), a result that was statistically significant (P  =  0.041). Left ventricle inflow/outflow obstruction is believed to be a critical pathogenic factor in the development of HLHS. Whereas 5 of 8 cases of HLHS had additional obstructive cardiac outflow tract lesions, 3 of 8 cases did not. PLSVC is known to be able to compromise left ventricle inflow via a dilated coronary sinus, and we speculate that PLSVC may have played a contributing role in the pathogenesis of HLHS in these three cases. As an isolated lesion, PLSVC would not be sufficient to cause HLHS, but it might contribute in combination with other obstructive lesions, or in the setting of other genetic and/or environmental factors still to be defined for HLHS. A larger series will be needed to confirm this hypothesis.

Clinical features and surgical outcome in 25 patients with fenestrations of the coronary sinus

OBJECTIVE

To analyze symptoms, associated anomalies, diagnostic approach, and surgical procedures in patients with partial fenestrations of the coronary sinus, a rare congenital disorder.

BACKGROUND

Partial fenestrations of the walls that usually separate the coronary sinus from the left atrium, also known as partial unroofing of the coronary sinus, may result in increased flow of blood to the lungs, cyanosis, or bidirectional shunting. The diagnosis is important, but difficult to confirm.

METHODS

We reviewed retrospectively the clinical, echocardiographic, operative, and follow-up data on 25 patients with partial fenestration of the coronary sinus. The patients had a median age of 8 years, and underwent cardiovascular surgery at Mayo Clinic between 1958 and 2003.

RESULTS

The initial diagnosis of a fenestration of the coronary sinus was made by the surgeon at repair of other congenital cardiac anomalies, by cardiac catheterization, or by echocardiography. In 14 patients, fenestration was missed during previous cardiovascular surgery. The most common associated cardiac lesions were atrial septal defects within the oval fossa, persistent left or right superior caval veins, and pulmonary or tricuspid atresia. In 7 patients, the symptoms were at least partially attributable to the fenestration, and included dyspnea, cerebral abscess, transient ischaemic attacks, and cyanosis. The fenestration was addressed surgically in 23 patients, and consisted of closure of the mouth of the coronary sinus, creation of an intra-atrial baffle, or direct repair of the fenestration. Death occurred in 1 patient due to complications unrelated to the repair. In the 24 early survivors, who have been followed up for a median of 85 months, 1 patient has died after a third reoperation for complex congenital cardiac disease.

CONCLUSIONS

Fenestrations of the coronary sinus are often missed in the preoperative evaluation of congenitally malformed hearts. When associated with right heart hypoplasia, atrial septal defect, or persistent superior caval vein, fenestrations of the coronary sinus should be considered as a possible additional finding. Once the diagnosis has been made, repair is straightforward.

The surgical anatomy and treatment of interatrial communications

Holes permitting shunting between the atrial chambers can take various anatomical forms, varying from the patent oval foramen, which shunts only from right-to-left, to the so-called sinus venosus defect, which is associated with anomalous connection of the pulmonary veins. Our review deals with all forms of interatrial communications, except for the so-called 'primum' defect, since although the lesion produces interatrial shunting of blood, the atrioventricular septal defect with common atrioventricular junction but separate valvar orifices for the right and left ventricles, is strictly an atrioventricular septal defect. In addition, the review illustrates in detail the morphological features of interatrial communications, and describes surgical challenges and approaches.

Development and structures of the venous pole of the heart

In the past, our interpretations of cardiac development depended on analysis of serially sectioned embryos, supported by three-dimensional reconstructions. It was not possible, using these techniques, to trace the fate of the various embryonic building blocks. This has all changed with the advent of the new techniques in molecular biology. Combining our experience with these new techniques and our previous studies using the classic approach, we have reviewed how the recent advances clarify controversies that still exist concerning the development of the venous pole. The arguments devolve on whether the pulmonary vein is itself a new development or whether its primordium is derived from the systemic venous tributaries, the so-called sinus venosus. The new techniques show that, rather than developing in the form of a segmented tube, the heart is built up by addition of material to both its arterial and venous poles. At no stage is it possible to recognize a discrete part of the tube that can be identified as the sinus venosus. The confluence of the systemic venous tributaries does not become recognizable as a discrete anatomic entity until compartmented into the newly formed right atrium concomitant with formation of the venous valves. The new molecular techniques show that the pulmonary vein is a new structure, anatomically and developmentally, that is derived from mediastinal myocardium. It gains its connection to the morphologically left atrium between the right- and left-sided systemic venous tributaries.

Normal and abnormal fetal cardiac anatomy

The heart is often perceived as a difficult organ to understand by ultrasound during fetal life. This is undoubtedly reflected in the low detection rate of cardiac abnormalities as compared to those of most other organ systems in the fetus. In this article we start by updating classical concepts of cardiac embryology, many of which were previously difficult to understand since they were overly simplistic or purely observational. We then lead on to the structure and growth of the fully formed fetal heart where we review the anatomy and ultrasound appearances in detail and provide comparisons with major abnormalities. We emphasise the fact that a solid understanding of cardiac anatomy can enable those involved in fetal medicine to make full use of the views of the heart that are obtained by ultrasound and which are often only transient.

Cardiac anatomy revisited

In tomorrow's world of clinical medicine, students will increasingly be confronted by anatomic displays reconstructed from tomographically derived images. These images all display the structure of the various organs in anatomical orientation, this being determined in time-honoured fashion by describing the individual in the 'anatomical position', standing upright and facing the observer. It follows from this approach that all adjectives used to describe the organs should be related to the three orthogonal planes of the body. Unfortunately, at present this convention is not followed for the heart, even though most students are taught that the so-called 'right chambers' are, in reality, in front of their 'left' counterparts. Rigorous analysis of the tomographic images already available, along with comparison with dissected hearts displayed in attitudinally correct orientation, calls into question this continuing tendency to describe the heart in terms of its own orthogonal axes, but with the organ positioned on its apex, so that the chambers can artefactually be visualized with the right atrium and right ventricle in right-sided position. Although adequate for describing functional aspects, such as 'right-to-left' shunting across intracardiac communications, this convention falls short when used to describe the position of the artery that supplies the diaphragmatic surface of the heart. Currently known as the 'posterior descending artery', in reality it is positioned inferiorly, and its blockage produces inferior myocardial infarction. In this review, we extend the concept of describing cardiac structure in attitudinally correct orientation, showing also how access to tomographic images clarifies many aspects of cardiac structure previously considered mysterious and arcane. We use images prepared using new techniques such as magnetic resonance imaging and computerized tomography, and compare them with dissection of the heart made in time-honoured fashion, along with cartoons to illustrate contentious topics. We argue that there is much to gain by describing the components of the heart as seen in the anatomical position, along with all other organs and structures in the body. We recognize, nonetheless, that such changes will take many years to be put into practice, if at all.