Coronary Artery Fistula
Coronary Artery Fistula
1. What is a coronary artery fistula (CAF)?
A. An abnormal connection between a coronary artery and a cardiac chamber, great vessel, or other vascular structure
B. A congenital narrowing of a coronary ostium
C. Atherosclerotic occlusion of the coronary artery
D. A septal defect connecting ventricles
CAF is an anomalous direct connection bypassing the myocardial capillary bed — between a coronary artery and chamber/vessel.
2. Which is the most common origin artery for CAF?
A. Left circumflex (LCx)
B. Right coronary artery (RCA)
C. Posterolateral artery
D. Coronary sinus
RCA is the most common origin, followed by LAD and LCx.
3. Most common drainage sites for CAF include:
A. Left ventricular cavity only
B. Coronary sinus rarely
C. Right-sided chambers and pulmonary artery (right atrium, right ventricle, pulmonary artery)
D. Carotid artery
CAF most often drains to low-pressure right-sided structures (RA, RV, PA) causing left-to-right shunt physiology.
4. Which is a recognized acquired cause of coronary artery fistula?
A. Viral myocarditis only
B. Idiopathic pulmonary hypertension
C. Congenital only
D. Iatrogenic injury after CABG or PCI, trauma, or endomyocardial biopsy
Acquired CAFs can follow surgery, trauma, or invasive coronary procedures.
5. The “coronary steal” phenomenon in CAF refers to:
A. Shunting of blood through the fistula away from myocardial capillaries leading to ischemia
B. Thrombosis of native coronary arteries
C. Increased coronary perfusion
D. Aortic valve regurgitation
High-flow fistulas divert blood to low-pressure receiving sites, potentially causing myocardial ischemia via steal.
6. Typical clinical finding often heard with a significant CAF is:
A. Mid-diastolic murmur only
B. Continuous machinery-like murmur (best heard over precordium)
C. No murmur ever
D. Systolic click
A continuous murmur due to continuous flow from coronary artery to low-pressure chamber or vessel is classic for larger CAFs.
7. Gold-standard test for anatomic definition of CAF is:
A. Transthoracic echo alone
B. ECG
C. Coronary angiography (invasive)
D. Chest X-ray
Coronary angiography gives detailed mapping of origin, course, and drainage — essential for planning closure.
8. Which noninvasive test gives excellent 3D anatomic detail of CAF?
A. Plain echo
B. Nuclear bone scan
C. Breathing test
D. CT coronary angiography (CTCA)
CTCA gives excellent spatial anatomy of fistula tract, aneurysmal dilation, and relationship to structures.
9. Indication for closure of a coronary artery fistula typically includes:
A. Symptoms (ischemia, heart failure), large shunt, aneurysm, or risk of endocarditis
B. Any tiny asymptomatic fistula always
C. Only when patient is over 80
D. Never — always observe
Large or symptomatic fistulas, aneurysmal channels, or fistulas causing ischemia are indications for closure.
10. Preferred initial closure method for many suitable CAFs is:
A. Medical therapy alone
B. Transcatheter closure (coil or device) if anatomy suitable
C. External compression
D. Liver transplant
Transcatheter techniques are less invasive and effective for many suitable fistulas; surgery reserved when anatomy is complex or percutaneous fails.
11. Which complication is a specific risk of large CAFs?
A. Aortic dissection
B. Pulmonary embolism from fistula
C. Heart failure from chronic volume overload
D. Appendicitis
Large left-to-right shunts via CAF can produce chronic volume overload and heart failure, especially if draining to right heart.
12. Which finding suggests CAF-related myocardial ischemia?
A. Elevated creatinine only
B. Increased white cell count
C. Absent pulses
D. Exertional angina with normal epicardial coronaries except the fistula
Ischemia may occur from coronary steal even when epicardial coronaries are otherwise unobstructed.
13. Which physical exam feature is classic for a moderate-to-large CAF?
A. Continuous murmur heard best in systole and diastole
B. Fixed split S2 only
C. Pericardial knock only
D. Diastolic rumble only
A continuous, machinery-like murmur due to persistent flow through the fistula is a hallmark when sizable.
14. Best management for an infected (endarteritis) coronary fistula is:
A. Watchful waiting
B. Antibiotics plus definitive closure (usually surgical) once stabilized
C. Anticoagulation only
D. Beta-blockers only
Infective endarteritis requires antibiotics and usually surgical management to remove infected tissues and close fistula.
15. Which imaging sign suggests aneurysmal change of a CAF?
A. Small linear flow only
B. Calcification only
C. Focal dilation of the fistula tract on CT or angiography
D. Thickened pericardium
Local dilation of the fistula channel is aneurysmal and raises risk of rupture or thrombus formation.
16. Following successful transcatheter closure of a CAF, the immediate follow-up includes:
A. No follow-up required
B. Lifelong anticoagulation by default
C. Immediate surgery
D. Short-term imaging (echo/CT) to confirm occlusion and monitor for residual flow or device complications
Imaging confirms closure and detects residual shunt, device migration, or complications.
17. In small asymptomatic CAF discovered incidentally, the usual strategy is:
A. Conservative follow-up with periodic imaging
B. Immediate surgical ligation always
C. Immediate closure with multiple stents
D. Endocardial biopsy
Small, asymptomatic fistulas can often be observed; intervention reserved for symptoms, enlargement, or complications.
18. Which hemodynamic effect is expected with large left-to-right draining CAF?
A. Systemic hypertension only
B. Volume overload of right heart and possibly pulmonary overcirculation
C. Immediate LV thrombus
D. Coronary vasospasm only
Shunting into right-sided structures increases right-sided volumes and can lead to pulmonary overcirculation and right-sided heart failure.
19. Which arrhythmia can be associated with coronary artery fistula?
A. SVT only
B. None ever
C. Atrial or ventricular arrhythmias due to ischemia or chamber dilation
D. ECG always normal
Ischemia, chamber enlargement, or conduction disturbances from fistula physiology can precipitate arrhythmias.
20. Key long-term risk of untreated large CAF is:
A. Immediate cure
B. Appendicitis
C. Constant chest pain only
D. Progressive heart failure, ischemia, endarteritis, or aneurysm-related complications
Significant untreated fistulas may progress to heart failure, cause ischemia, become infected, or develop aneurysmal complications.
| No. | Question | Short Answer |
|---|---|---|
| 1 | What is a CAF? | An abnormal connection from coronary artery to chamber/vessel bypassing capillaries. |
| 2 | Most common origin | Right coronary artery (RCA). |
| 3 | Typical drainage sites | Right atrium, right ventricle, pulmonary artery, coronary sinus. |
| 4 | Congenital or acquired? | Mostly congenital; can be acquired after surgery, trauma, or interventions. |
| 5 | Common clinical sign | Continuous machinery-like murmur. |
| 6 | Pathophysiology | Coronary steal and left-to-right shunt causing ischemia/volume overload. |
| 7 | Best diagnostic test | Coronary angiography for anatomic mapping. |
| 8 | Noninvasive mapping | CT coronary angiography (CTCA). |
| 9 | Indication for closure | Symptoms, large shunt, aneurysm, ischemia, or endarteritis risk. |
| 10 | Preferred closure | Transcatheter coil/device closure if anatomy suitable. |
| 11 | Surgical role | Surgical ligation for complex anatomy or failed percutaneous closure. |
| 12 | Complications | Heart failure, ischemia, arrhythmia, aneurysm, endarteritis. |
| 13 | Small asymptomatic CAF | Often conservative follow-up with periodic imaging. |
| 14 | CAF and infective endarteritis | Requires antibiotics and often surgical removal/closure. |
| 15 | Aneurysmal fistula sign | Focal dilation along fistula course on CT/angio. |
| 16 | Hemodynamics | Large fistulas cause right-sided volume overload and pulmonary overcirculation. |
| 17 | Arrhythmia risk | Yes — atrial or ventricular arrhythmias may occur. |
| 18 | Follow-up after closure | Imaging (echo/CT) to confirm occlusion and check device position. |
| 19 | CTA vs angio | CTA excellent for 3D anatomy; angio for interventional planning. |
| 20 | Long-term risk if untreated | Progressive heart failure, ischemia, aneurysm rupture, or infection. |
Coronary Artery Fistula (CAF) – Overview
A coronary artery fistula is an abnormal connection between a coronary artery and a cardiac chamber, great vessel, or other vascular structure, bypassing the myocardial capillary network.
Key Points:
- Etiology:
- Congenital (most common) – due to abnormal embryonic development of coronary vasculature
- Acquired – post-cardiac surgery, trauma, endomyocardial biopsy, or invasive coronary interventions
- Common Sites of Origin:
- Right coronary artery (RCA) – most frequent
- Left anterior descending (LAD) artery
- Left circumflex (LCx) artery
- Common Sites of Drainage:
- Right atrium
- Right ventricle
- Pulmonary artery
- Coronary sinus
- Less common – left atrium, left ventricle, superior vena cava
- Pathophysiology:
- Shunt from high-pressure coronary artery to low-pressure receiving chamber/vessel → coronary steal phenomenon → myocardial ischemia
- Clinical Features:
- Often asymptomatic (especially small fistulas)
- Symptomatic cases: exertional angina, dyspnea, palpitations, fatigue, signs of heart failure, or continuous murmur
- Large fistulas may cause myocardial ischemia, arrhythmias, or heart failure
- Complications:
- Myocardial ischemia (due to steal)
- Heart failure
- Endocarditis/endarteritis
- Arrhythmias
- Aneurysm formation and rupture
- Diagnosis:
- Echocardiography (especially TEE) – detects abnormal flow
- Coronary angiography – gold standard for anatomic definition
- CT coronary angiography – non-invasive detailed imaging
- Treatment:
- Small, asymptomatic – conservative follow-up
- Symptomatic or large fistulas – closure by:
- Catheter-based techniques (coil embolization, plug device)
- Surgical ligation (especially if complex anatomy or failed percutaneous closure)
