Download Unroofed Coronary Sinus – A Rare Type of ASD

DECEMBER 2012
ISSUE 51
Unroofed Coronary Sinus – A Rare Type of ASD
Ali Karaosmanoglu, MD, Mannudeep Kalra, MD; Moussa Mansour, MD; Wilfred Mamuya, MD, PhD; Suhny Abbara, MD
Clinical History
A 53-year old man presented to the cardiology clinic with a
shortness of breath and atrial fibrillation with a rapid ventricular
response. His past medical history was remarkable for
hypertension, hyperlipidemia and a non ST - segment elevation
myocardial ischemia. A computed tomography angiogram
(CTA) evaluation of the pulmonary veins was requested as a
part of pre-procedural work - up for endovascular pulmonary
vein isolation.
Findings
Contrast enhanced CT examination revealed normal pulmonary
vein anatomy. The coronary sinus was found to be mildly dilated
in the left atrioventricular groove (figure 1, 2) and there was
also a 2.2 cm segment of abnormal communication between
the base of the left atrium and the roof of the coronary sinus,
consistent with an unroofed coronary sinus (figure 3). There
was no evidence of persistent left sided superior vena cava
(LSVC). Contrast material was seen entering the coronary sinus
at the site of unroofing and it shunted into the right atrium via
the normal coronary sinus ostium. As there was no clinically
significant amount of shunting no shunt related intervention was
made and the patient was continued to be medically managed.
Discussion
Unroofed coronary sinus is a rare congenital cardiac anomaly
which might be difficult to diagnose (1). It is classified as an atrial
septal defect and constitutes the rarest form of this group of
congenital heart disease (2). The anatomic abnormality is variable
and classified into four groups: type 1, completely unroofed
with persistent LSVC; type 2, completely unroofed without
persistent LSVC; type 3, partially unroofed mid portion; and type
4, partially unroofed terminal portion (2). The presented case
appears to be consistent with type 4 subgroup of this anomaly.
The development of symptoms appears to be related to the size
of the defect, and the severity of the inter-atrial shunt, which
may lead to the development of right heart failure. The diagnosis
should be suspected in a patient with LSVC and associated brain
abscess or cerebral emboli; or in a patient with unexplained arterial
oxygen desaturation (1). Management depends on the clinical
Figure 1A
Figure 1B
Figure 1C
Figure 2
Figure 1(A,B,C): Contrast enhanced ECG gated axial CT images at
different levels demonstrate the mildly enlarged non-opacified coronary
sinus (1A, white arrow) an abnormal communication with the left atrium
(1B, arrow) more downstream, and contrast opacificied distal coronary
sinus entering the right atrium (1C).
Figure 2: Sagittal oblique reformatted image demonstrates the course
of the coronary sinus (arrows). Note the abnormal communication
(unroofing) of the coronary sinus with the left atrium (arrowheads). Note
the horizontal lines indicate the axial slice positions from figure 1.
symptoms and surgical intervention should be considered
when the symptoms cannot be managed medically.
Imaging plays a crucial role in the diagnosis. Transthoracic
echocardiography is, limited in its ability to evaluate the
posterior structures. Cross sectional imaging with computed
tomography (CT) and magnetic resonance imaging Are
well suited to identify this abnormality.
REFERENCES
1. Ngee T, Lim MC, De Larrazabal C, Sundaram RD. Unroofed coronary sinus defect. J Comput Assist Tomogr 2011; 35: 246-247.
2. Ootaki Y, Yamaguchi M, Yoshimura N, Oka S, Yoshida M, Hasegawa T. Unroofed coronary sinus syndrome: diagnosis, classification and surgical
treatment. Journal of Thoracic and Cardiovascular Surgery 2003;126:1655-1656.
Editors:
Suhny Abbara, MD, MGH Department of Radiology
Wilfred Mamuya, MD, PhD, MGH Division of Cardiology