Image Question-59

What is the structure marked ?


A. Cor triatriatum
B. Parachute mitral valve
C. Mitral valve prolapse
D. Dilated coronary sinus




Aneurysmal dilated coronary sinus – structure (yellow arrow)


A dilated coronary sinus (CS) on echocardiography or imaging is an important clue to underlying pathology.

Causes of a Dilated Coronary Sinus

  1. Persistent left superior vena cava (PLSVC) – most common cause.
  2. Elevated right atrial pressure – secondary to:
    • Right heart failure
    • Pulmonary hypertension
    • Severe tricuspid regurgitation
    • Constrictive pericarditis
  3. Coronary arteriovenous fistula draining into the coronary sinus.
  4. Unroofed coronary sinus (rare congenital anomaly, may be associated with atrial septal defect).
  5. Iatrogenic causes – e.g., pacemaker or ICD leads placed via CS.

👉 In exams, dilated coronary sinus is a red flag for persistent LSVC until proven otherwise.


Q1. The most common cause of a dilated coronary sinus is:

A. Persistent left superior vena cava
B. Right atrial hypertension
C. Tricuspid regurgitation
D. Coronary arteriovenous fistula
Persistent LSVC is the most common cause of a dilated coronary sinus.

Q2. Which echocardiographic view best shows a dilated coronary sinus?

A. Parasternal short-axis
B. Apical 4-chamber view
C. Subcostal IVC view
D. Suprasternal view
The apical 4-chamber view shows the coronary sinus posterior to the left atrium.

Q3. A dilated coronary sinus with bubble contrast appearing after left arm injection indicates:

A. Right SVC obstruction
B. Pulmonary AV malformation
C. Persistent left SVC
D. Unroofed coronary sinus
Contrast injection in left arm opacifying CS confirms persistent LSVC.

Q4. Which congenital anomaly is most commonly associated with a dilated coronary sinus?

A. ASD secundum
B. VSD
C. TOF
D. Persistent LSVC
Persistent LSVC is the key congenital anomaly linked with CS dilatation.

Q5. Elevated right atrial pressure may cause CS dilation in all EXCEPT:

A. Severe tricuspid regurgitation
B. Pulmonary hypertension
C. Hypertrophic cardiomyopathy
D. Constrictive pericarditis
HCM does not typically cause right atrial hypertension leading to CS dilatation.

Q6. Which rare congenital defect directly involves the coronary sinus wall?

A. Unroofed coronary sinus
B. Coronary AV fistula
C. Ebstein anomaly
D. PAPVR
An unroofed CS is a rare congenital defect where the wall between CS and LA is absent.

Q7. Which invasive procedure most often uses the coronary sinus?

A. Balloon mitral valvotomy
B. PCI
C. LV pacing lead insertion (CRT)
D. Right heart catheterization
LV pacing lead for CRT is introduced via the coronary sinus tributaries.

Q8. CS dilation in the absence of LSVC or RA hypertension should raise suspicion of:

A. Coarctation of aorta
B. Coronary AV fistula
C. Subaortic stenosis
D. PDA
A coronary AV fistula draining into CS can dilate it without RA pressure overload.

Q9. Which valve abnormality is LEAST likely to cause CS dilation?

A. Severe TR
B. Mitral valve prolapse
C. Tricuspid stenosis
D. Pulmonary valve stenosis with RV failure
MVP primarily affects the left atrium and does not cause RA hypertension → CS dilation.

Q10. Which imaging modality best delineates an unroofed coronary sinus?

A. Chest X-ray
B. Transthoracic echo
C. Cardiac MRI / CT
D. Coronary angiogram
Cardiac MRI/CT provides excellent anatomic detail of rare anomalies like unroofed CS.

Q11. During echo, a circular echo-free structure posterior to LA suggests:

A. Dilated descending aorta
B. Dilated coronary sinus
C. Pericardial cyst
D. Left atrial appendage
A dilated coronary sinus appears as a circular echo-free structure behind the LA.

Q12. Which test helps differentiate persistent LSVC from other causes of CS dilatation?

A. Bubble contrast echo with left arm injection
B. Right heart catheterization
C. Exercise stress echo
D. Tilt table test
Contrast opacification of CS after left arm injection strongly indicates LSVC.

Q13. Which syndrome is associated with unroofed coronary sinus?

A. Holt-Oram syndrome
B. Raghib syndrome
C. Marfan syndrome
D. Noonan syndrome
Raghib syndrome = unroofed CS with LSVC draining into LA → right-to-left shunt.

Q14. Dilated CS is most likely to be mistaken for which echo structure?

A. Right atrial appendage
B. Descending aorta
C. Main pulmonary artery
Dilated CS lies posterior to LA and can mimic descending aorta in echo.

Q15. In CRT device placement, the lead in coronary sinus is used to pace:

A. Right atrium
B. Right ventricle
C. Left ventricle
D. His bundle
CS lead is placed in a tributary vein to pace the LV free wall.

Q16. Which is NOT a consequence of dilated coronary sinus?

A. LV outflow obstruction
B. Misinterpretation as mass
C. Difficult CRT lead placement
D. Associated arrhythmias
Dilated CS does not obstruct LVOT but may complicate interventions or be misdiagnosed.

Q17. Which pressure abnormality most directly causes CS dilation?

A. Elevated right atrial pressure
B. Elevated LA pressure
C. Elevated LVEDP
D. Low RA pressure
High RA pressure is transmitted to CS → dilation.

Q18. In persistent LSVC, coronary sinus drains blood into:

A. Left atrium
B. Right atrium via coronary sinus
C. Pulmonary veins
D. IVC
In most cases, LSVC drains into RA via CS, causing its dilatation.

Q19. Which anomaly may result in systemic desaturation with a dilated CS?

A. LSVC to RA
B. LSVC draining into LA
C. Coronary AV fistula to CS
D. CS dilatation from RA hypertension
When LSVC drains into LA, venous blood bypasses lungs → cyanosis & desaturation.

Q20. Which intervention may be complicated by an unrecognized dilated CS?

A. TAVR
B. CRT device implantation
C. Pulmonary vein isolation
D. Mitral clip
CRT requires CS lead access; abnormal anatomy complicates procedure.

Here are the keywords for Dilated Coronary Sinus (separated by commas as you prefer):

Dilated coronary sinus, Persistent left superior vena cava, PLSVC, Right atrial pressure, Right heart failure, Pulmonary hypertension, Severe tricuspid regurgitation, Constrictive pericarditis, Coronary arteriovenous fistula, Unroofed coronary sinus, Congenital heart disease, Pacemaker lead, ICD lead, Cardiac venous anatomy, Echocardiography coronary sinus, Bubble contrast echocardiography, Coronary sinus dilation causes, Coronary sinus anomalies, Left arm contrast injection, Dilated coronary sinus differential diagnosis


    Subscribe Medicine Question BankWhatsApp Channel

    FREE Updates, MCQs & Questions For Doctors & Medical Students

      Medicine Question Bank