Partially unroofed coronary sinus and persistent left superior vena cava: intracardiac echocardiographic observation

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.

Successful slow pathway ablation in a patient with a rare unroofed type coronary sinus

We report a case of atrioventricular nodal reentrant tachycardia coexistent with a coronary sinus (CS) anomaly. During a standard electrophysiological study, the CS could not be cannulated despite several attempts. A persistent left superior vena cava angiogram through the left brachial vein confirmed an unroofed type CS. Successful slow pathway ablation from the right posterior paraseptum lesion was achieved using an anatomical approach.

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.

Interatrial communication through the mouth of the coronary sinus

OBJECTIVES

We describe the structure of, and suggest an etiology for, the interatrial communication which can occur through the mouth of the coronary sinus. Based on the study of human embryos, we propose that the defect is best explained by dissolution of the wall of the coronary sinus adjacent to the left atrium, permitting shunting between the atriums through the right atrial orifice of the sinus.

BACKGROUND

An interatrial communication across the mouth of the coronary sinus defect was first described in 1965 by Raghib and colleagues, its existence being predicated on the basis of incomplete formation of the left "atriovenous fold". Their hypothesis implies that the coronary sinus never develops, and thus the atrial septum itself is incomplete.

METHODS

We have studied the development of the coronary sinus in a series of human embryos. Based on this work, we present the anatomical findings in 6 specimens with varying degrees of dissolution of the walls of the coronary sinus, and ten specimens with isomerism of the right atrial appendages, in which the sinus has never been formed.

RESULTS

The coronary sinus defect is not a hole within the atrial septum, but a communication between the atriums through the mouth of the sinus. There was a range of defects in our series of specimens with usual atrial arrangement, extending from complete absence of the walls which normally separate the coronary sinus from the left atrium, to small fenestrations between this vessel and the left atrial cavity. In the hearts with isomerism of the right atrial appendages, however, we never observed an orifice of the coronary sinus. Thus, a coronary sinus defect cannot exist in this setting.

CONCLUSIONS

Our findings indicate that the defect requires initial formation of the walls of the coronary sinus, but with subsequent dissolution of the wall adjacent to the left atrium. This produces a communication between the atriums through the mouth of the sinus.

Intracardiac echocardiography via the transvenous approach with use of 8F 10-MHz ultrasound catheters

OBJECTIVE

To study the safety and feasibility of intracardiac imaging using a novel 8F 10-MHz non-over-the-wire ultrasound catheter system.

SUBJECTS AND METHOD

Intracardiac imaging using a transfemoral venous approach was performed in 33 adults, 14 men and 19 women, aged 25 to 66 years (mean, 46 years). Six were normal subjects, 12 had congenital heart diseases (5 atrial septal defects, 3 ventricular septal defects, 1 tetralogy of Fallot, 2 patent ductus arteriosus, and 1 Ebstein anomaly), 14 had valvular heart diseases (12 mitral stenoses and 2 calcific aortic stenoses), and 1 had acute pulmonary embolism.

RESULTS

Ultrasound images were obtained, without any complications, from the right side of the heart in all subjects. The atria and ventricles could be recognized by anatomic relationships to the cardiac chambers and the valves by their characteristic motion during each cardiac cycle. The vessels were verified by their connections to the cardiac chamber and by contrast echocardiography if indicated.

CONCLUSION

Intracardiac imaging using the 8F 10-MHz non-over-the-wire ultrasound catheter system via a transfemoral venous approach is feasible and safe. Intracardiac echocardiography is potentially useful for assessing a variety of cardiac anomalies and in guiding and monitoring certain intervention procedures.