Coronary artery fistula
Anatomy & Projection Angles
Epicardial Flow & Myocardial Perfusion
Synonyms and Keywords: CAF, CAVF
A coronary artery fistula is any abnormal communication through which coronary artery blood is shunted into a cardiac chamber, great vessel, or other vascular structure without first passing through the myocardial capillary bed. The number, origin, and course of the coronary arteries is otherwise normal.
The coronary artery fistula can terminate in:
- Any of the cardiac chambers
- The vessels of Wearn that empty into the cardiac chambers
- The coronary sinus
- The SVC
- The pulmonary veins
- The mediastinal vessels
Fistulas may enter as a single vessel or as a plexus with multiple small entry sites, the fistulous opening may occur at the end of a main vessel or one of its branches or in the middle of the vessel forming a side-to-side anastomosis.
Progressive dilatation of the fistulous connection can occur due to the effect of increasing flow through the vessel over time, rather than a defect in the vessel wall.
When the coronary fistula connects to a right-sided chamber or vessel (RA, RV, or PA), there is a left-to-right shunt with increased flow delivered to the pulmonary circulation and ultimately to the left heart.
Patients with coronary artery fistulas can experience myocardial infarction in the absence of other coronary artery pathology. This can because the fistula competes for flow with the normal circulation.
- Gunshot wounds and shrapnel
- Stab wounds
- Inadvertent placement of an SVG graft to a coronary vein
- Secondary to large atherosclerotic coronary aneurysms
- As a complication of acute MI
- Repeated endomyocardial biopsies in transplant patients with a fistula to the RV.
Epidemiology and Demographics
The incidence in angiographic studies is .08% to .3% (usually an incidental finding at the time of angiography for another problem), but is important to know that the true incidence is unknown given that many coronary artery fistulas are small and undetected in life. Coronary artery fistula remains a postmortem diagnosis, and 15% of coronary artery anomalies are due to coronary artery fistulas.
Natural History, Complications, Prognosis
- Highly variable. Many patients remain asymptomatic, others develop symptoms after a long asymptomatic period.
- Spontaneous closure can occur in infancy, but is unusual in adulthood.
In the March 2010 Circulation article titled “Predictors of Long-Term Adverse Outcomes in Patients With Congenital Coronary Artery Fistulae”, Valente et al discuss long-term outcomes of patients with treated and untreated coronary artery fistula (CAF) closure.  Specifically, investigation was directed at whether or notclinical and angiographic features associated with CAF closure (symptomatic heart failure, angina and myocardial infarction) predict adverse outcomes.
Predictors of adverse outcome
- Angiographic predictors
Drainage of CAF into the coronary sinus (P<0.001)
- Clinical predictors
*Systemic hypertension (P<0.001)
*Older age at diagnosis (P<0.001)
*Tobacco use (P=0.006)
Differentiation form other Disorders
On angiography, a coronary artery fistula must be distinguished from a tumor blush, or arterial blood flow to a myxoma.
- CHF occurs in about 20% of these patients, usually with fistulas draining into the RV or RA.
- Those draining into the left side of the heart cause dyspnea, fatigue or ischemia.
- There is no good relationship between the size of the fistula and symptoms.
- The most common physical finding is a continuous murmur.
- If the fistula is connected to the pulmonary artery, then the murmur will be best heard in the left 2nd or 3rd interspace.
- With fistulas draining into the RA, the murmur is best heard to the right of the sternum.
- Fistulas draining into the RV or LA are best heard at the lower left sternal border or subxyphoid areas. Usually the diastolic component is louder in a fistula to the RV because the decreasing size of the hole during systolic contraction, and the systolic component is louder when connected to the PA or the atria.
- Fistulas to the LV are least likely to cause a murmur.
- May show chamber enlargement
Chest X Ray
Echocardiography or Ultrasound
- A coronary artery fistula can be visualized on ECHO as an enlarged lumen arising from the aortic root or in a more distal location, with continuous or turbulent flow. Angiographic confirmation is usually necessary.
Surgery and Device Based Therapy
Indications for Surgery
- Surgery is necessary for the management of symptomatic fistulas. Murmurs are more frequent in those with symptoms and in those who ultimately require surgery.
- Most have an improvement in symptoms postoperatively.
2008 ACC/AHA Guidelines for the Management of Adults With Congenital Heart Disease (DO NOT EDIT)
Coronary Arteriovenous Fistula (DO NOT EDIT)
|"1. If a continuous murmur is present, its origin should be defined either by echocardiography, MRI, CTangiography, or cardiac catheterization. (Level of Evidence: C)"|
|”2. A large coronary arteriovenous fistula (CAVF), regardless of symptomatology, should be closed via either a transcatheter or surgical route after delineation of its course and its potential to fully obliterate the fistula. (Level of Evidence: C)"|
|”3. A small to moderate CAVF in the presence of documented myocardial ischemia, arrhythmia, otherwise unexplained ventricular systolic or diastolic dysfunction or enlargement, or endarteritis should be closed via either a transcatheter or surgical approach after delineation of its course and its potential to fully obliterate the fistula. (Level of Evidence: C)"|
|"1. Patients with small, asymptomatic CAVF should not undergo closure of CAVF. (Level of Evidence: C)"|
|"1. Clinical follow-up with echocardiography every 3 to 5 years can be useful for patients with small, asymptomatic CAVF to exclude development of symptoms or arrhythmias or progression of size or chamber enlargement that might alter management. (Level of Evidence: C)"|
- Valente AM, Lock JE, Gauvreau K; et al. (2010). "Predictors of Long-Term Adverse Outcomes in Patients With Congenital Coronary Artery Fistulae". Circ Cardiovasc Interv. doi:10.1161/CIRCINTERVENTIONS.109.883884. PMID 20332380. Unknown parameter
- Warnes CA, Williams RG, Bashore TM, Child JS, Connolly HM, Dearani JA; et al. (2008). "ACC/AHA 2008 guidelines for the management of adults with congenital heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Develop Guidelines on the Management of Adults With Congenital Heart Disease). Developed in Collaboration With the American Society of Echocardiography, Heart Rhythm Society, International Society for Adult Congenital Heart Disease, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons". J Am Coll Cardiol. 52 (23): e1–121. doi:10.1016/j.jacc.2008.10.001. PMID 19038677.