J A C C : C A R D I O V A S C U L A R I M A G I N G VO L . 1 1 , N O . 7 , 2 0 1 8

ª 2 0 1 8 B Y T H E AM E R I C A N C O L L E G E O F C A R D I O L O G Y F O UN DA T I O N

P U B L I S H E D B Y E L S E V I E R

IMAGING VIGNETTE

Multimodality Cardiovascular Imaging ofUnroofed Coronary Sinus Defects

Bo Xu, MBBS (HONS),a Jorge Betancor, MD,a Paul C. Cremer, MD,a Rahul Renapurkar, MD,b Gosta B. Pettersson, MD,c

Craig R. Asher, MD,d L. Leonardo Rodriguez, MDa

UNROOFED CORONARY SINUS (CS) DEFECTS ARE RARE ANOMALIES THAT RESULT FROM EMBRYOLOGIC

developmental abnormalities, leading to partial or complete absence of the common wall between the CS andthe left atrium. They account for less than 1% of atrial septal defects, having a strong association with apersistent left superior vena cava, and are often difficult to diagnose. Delayed diagnosis may lead to rightventricular enlargement and failure, and pulmonary hypertension. Here, we present the multimodalitycardiovascular imaging findings of unroofed CS defects (Figures 1 to 5). For simplicity, unroofed CS defects areclassified as types I, II, and III, referring to complete unroofing, partial unroofing of the mid-portion, and

A BLEFTARM

RIGHTARM

L

PR

A

C D

FIGURE 1 TTE and MDCT of a Patient With a Persistent LSVC

and Unroofed CS Defect

(A) Transthoracic echocardiography (TTE) (apical 4-chamber view)

demonstrating right-sided chamber enlargement. (B) After injec-

tion of agitated saline via the left arm, prominent contrast is seen in

the left heart with minimal opacification of right-sided chambers.

This confirms the presence of an unroofed coronary sinus (CS)

defect. (C) After injection of agitated saline via the right arm,

prominent contrast is seen in the right atrium and ventricle, with a

small amount of bubbles seen in the left-sided chambers. This

confirms the presence of a right-to-left intracardiac shunt.

However, this finding is not specific for unroofed CS defects. (D)

Note that the CS is not visualized in a true apical 4-chamber view, as

illustrated in this multidetector cardiac computed tomography

(MDCT) reconstruction, given the inferior and posterior location

of the CS. A ¼ anterior; L ¼ left; LSVC ¼ left superior vena cava;

P ¼ posterior; R ¼ right.

ISSN 1936-878X/$36.00 https://doi.org/10.1016/j.jcmg.2018.03.001

From the aSection of Cardiovascular Imaging, Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio; bDepartment of

Diagnostic Radiology, Imaging Institute, Cleveland Clinic, Cleveland, Ohio; cDepartment of Thoracic and Cardiovascular

Surgery, Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio; and the dDepartment of Cardiovascular Medicine,

Heart and Vascular Institute, Cleveland Clinic Florida, Weston, Florida. The authors have reported that they have no

relationships relevant to the contents of this paper to disclose. Drs. Xu and Betancor contributed equally to this work and are

joint first authors.

Manuscript received March 8, 2017; revised manuscript received February 5, 2018, accepted March 1, 2018.

FIGURE 2 TTE and MDCT of a Patient With a Persistent LSVC and Unroofed CS Defect

A

CS CS

CS

CSCS

RA

LA

LA

RUPV

RA

RV

-61cm/s

B C

D E F

(A) TTE (parasternal right ventricular [RV] inflow view), showing a dilated CS draining into the right atrium (RA). (B) TTE (parasternal RV inflow

view) with color Doppler imaging, showing flow from the dilated CS reaching the RA. (C)MDCT reconstruction of the RV inflow view. Note the

dilated CS draining into the RA, without a wall separating it from the left atrium (LA). Note the right upper pulmonary vein (RUPV) draining into

the LA, which communicates freely with the CS. (D) TTE (subcostal 4-chamber view) showing the communication between the atria. Note how

inferior the imaging plane must be in order to identify the defect in a 4-chamber view. (E) TTE (subcostal 4-chamber view with color Doppler

imaging) demonstrating communication between the atria. At the time of TTE imaging, a subcostal sweep in coronal and sagittal planeswill help

delineate the anatomyof the unroofed CS defect. (F)MDCT reconstruction of the subcostal short-axis view at the atrial/CS level, emphasizing the

inferior and posterior location of unroofed CS defects. This illustrates how easily unroofed CS defects can bemissed by TTE if dedicated off-axis

imaging planes are not acquired. It is important to note that unroofed CS defects are located posteriorly to the entrance of the inferior vena

cava into the RA, differentiating them from inferior sinus venosus atrial septal defects, on MDCT reconstruction. The double-headed arrow

highlights the unroofed coronary sinus, and the potential for interatrial shunting (either left-to-right, or right-to-left, depending on pressure

differences between the left atrium and right atrium). Abbreviations as Figure 1.

Xu et al. J A C C : C A R D I O V A S C U L A R I M A G I N G , V O L . 1 1 , N O . 7 , 2 0 1 8

Imaging of Unroofed Coronary Sinus Defects J U L Y 2 0 1 8 : 1 0 2 7 – 3 0

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partial unroofing of the terminal portion, respectively. Echocardiography is the first-line imaging modality,whereas multidetector cardiac computed tomography provides detailed anatomical information, whenechocardiography is not diagnostic. Cardiac magnetic resonance imaging is useful as an adjunct, particularlywhen quantification of intracardiac shunting is required (Figure 6).

A B

C D

CS

CS

LA

LA

LAA

Aorta

FIGURE 3 TTE and MDCT of a Patient With a Persistent LSVC and

Unroofed CS Defect

(A) TTE (apical 2-chamber view) of a patient with an unroofed CS

defect and a persistent LSVC. Note the dilated CS freely communi-

cating with the LA without a separating membrane. (B) MDCT recon-

struction of the apical 2-chamber view shown in Figure 3A, showing

the unroofed CS just posterior to the LA, confirming the absence of a

membrane separating the CS from the LA. (C) TTE (apical 3-chamber

view) in a patient with an unroofed CS and a persistent LSVC. Note that

the CS is not well visualized in the apical 3-chamber view (white arrow).

(D) MDCT reconstruction of the 3-chamber view shown in

Figure 3C, demonstrating why the CS is poorly visualized in this view,

given that it lies perpendicular to the cross-sectional imaging plane

(white arrow). LAA ¼ left atrial appendage; other abbreviations as in

Figures 1 and 2.

H

A

RA

RV

JPEG

LA

B C

FIGURE 4 TEE and MDCT of a Patient With a Type III

Unroofed CS Defect and an Absent LSVC

(A) Transesophageal echocardiography (TEE) (lower

esophageal view at the gastroesophageal junction; 0�),

showing a type III unroofed CS defect. Note the partial

absence of CS wall (arrow, dashed line), which allows

communication between the right and left atria. (B)

MDCT showing a type III unroofed CS defect. This is the

optimal CS MDCT reconstruction to identify the presence,

as well as the location and extent of a CS defect

(dashed white line and black arrows). Note the similar

contrast intensities within the LA and CS, due to the

absent wall in the terminal portion of the CS. Note the

well-demarcated margin separating the LA from the CS

in its proximal to mid-portion. (C) Pseudo-2-chamber

MDCT reconstruction, showing a type III unroofed CS

defect with absent wall in the terminal portion of the CS

(black arrow), which allows communication with the

LA. Note the similar contrast intensities within the LA

and CS. It is also important to note that to demon-

strate the posterior location of the unroofed CS defect,

modified coronal and oblique sagittal MDCT pro-

jections are used. Abbreviations as in Figures 1 and 2.

J A C C : C A R D I O V A S C U L A R I M A G I N G , V O L . 1 1 , N O . 7 , 2 0 1 8 Xu et al.J U L Y 2 0 1 8 : 1 0 2 7 – 3 0 Imaging of Unroofed Coronary Sinus Defects

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LA

CS

CS

RA

CS

JPEG

A B

C D

FIGURE 5 TEE and MDCT of a Patient With a Type II Unroofed CS Defect

and Absent LSVC

(A) TEE (lower esophageal view at the gastroesophageal junction; 0�)

showinga type II unroofedCSdefectwithpartial absence of tissue in themid-

portion of the CSwall (arrow, dashed line), allowing communication with LA.

Note the normal wall at the terminal portion of the CS. (B)MDCT recon-

struction in a patient with a type II unroofed CS defect. Contrast opacifi-

cation in the CS is similar to that in the left ventricle. The CS appears to drain

normally into theRA,withaverywelldemarcatedwall around it; however, this

reconstructiondoesnothelpelucidate thepresenceofanunroofedCS, as the

defect will always be adjacent to the LA, which is not seen in this recon-

struction. (C) Pseudo-2-chamber MDCT reconstruction, demonstrating a

type II unroofedCSdefectwith absentwall in themid-portion of the CS (black

arrow), allowing communicationwith theLA. Contrastopacification in theCS

is similar to that in the left ventricle. This reconstruction allows identifica-

tion of type II unroofed CS defects (mid-portion). However, a type III CS

defect (terminalportion)couldbemissed,unless it is sufficiently large. (D)This

is theoptimalCSMDCT reconstruction to identify thepresence, aswell as the

location and extent of a CS defect (black arrow). Note the similar contrast

intensitieswithin theLAandCS, due to the absentwall in themid-portionof

the CS; however, there is a well demarcatedmargin separating the LA from

theCS in its terminalportion. It is also important tonote that todemonstrate

the posterior location of the unroofed CS defect, modified coronal and

oblique sagittal MDCT projections are used. Abbreviations as in

Figures 1, 2, and 4.

CS CS

LA LA

LVRA

A B FIGURE 6 CMR Imaging of a Patient

With a Type I Unroofed CS Defect and a

Persistent LSVC

(A) Steady-state free precession

sequence demonstrating a basal slice

of the left ventricular (LV) short-axis

stack. Note that this view is similar to

the MDCT reconstructions shown in

Figure 4, all of which allow for an

excellent display of the different types

of unroofed CS defects. The dashed

line demarcates the totally absent

tissue between the LA and the CS

(arrow). (B) Two-chamber reconstruc-

tion showing a type I unroofed CS

defect with totally absent wall be-

tween the CS and the LA (arrow).

Compare with echocardiographic and

MDCT assessment of unroofed CS

defects in Figures 1 to 5. CMR ¼cardiac magnetic resonance; other

abbreviations as in Figures 1 and 2.

Xu et al. J A C C : C A R D I O V A S C U L A R I M A G I N G , V O L . 1 1 , N O . 7 , 2 0 1 8

Imaging of Unroofed Coronary Sinus Defects J U L Y 2 0 1 8 : 1 0 2 7 – 3 0

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ADDRESS FOR CORRESPONDENCE: Dr. Bo Xu, Section of Cardiovascular Imaging, Heart and VascularInstitute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, Ohio 44195. E-mail: xub@ccf.org.

KEY WORDS cardiac magnetic resonance imaging, echocardiography, multidetector cardiac computed tomography, multimodality imaging,unroofed coronary sinus