Coronary artery fistula

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Coronary Angiography

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Coronary arteries
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Left Anterior Descending
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Anatomic Variants

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Case Example
Fistula

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Epicardial Flow & Myocardial Perfusion

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Lesion Complexity

ACC/AHA Lesion-Specific Classification of the Primary Target Stenosis

Preprocedural Lesion Morphology

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Lesion Morphology

Quantitative Coronary Angiography
Definitions of Preprocedural Lesion Morphology
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Technique
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-in-Chief: Leida Perez, M.D.

Synonyms and Keywords: CAF, CAVF

Overview

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.

Anatomy

The coronary artery fistula can terminate in:

  1. Any of the cardiac chambers
  2. The vessels of Wearn that empty into the cardiac chambers
  3. The coronary sinus
  4. The SVC
  5. The pulmonary veins
  6. The mediastinal vessels

Incidental fistulas are more likely to be multiple. If the coronary artery fistula is originated from the left coronary artery, is less likely to terminate in the RV.

Symptomatic fistulas from case reports are more likely to be single, require surgery, cause chest pain, result in a continuous murmur, and drain into the RA or RV.

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.

Pathophysiology

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.

The left-to-right shunt is usually small with a 1.5:1 ratio, not infrequently the magnitude of the shunt is so small as to not be quantifiable by oximetry, indicator dilution methods etc.

Large fistulas draining into the LA or the LV can cause volume overload similar to that caused by aortic insufficiency.

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.

Since the coronary circulation often has a higher resistance to flow there can be coronary steal, and effect can be visualized on thallium scanning.

Using electromagnetic flow probes, studies have shown a 2.5 fold increase in flow to the distal vessel when the fistula is occluded.

Symptoms and the scintigraphic abnormality may disappear with ligation.

Causes

Congenital

Approximately 75% of coronary artery fistulas are congenital in origin. They develop at week 6 to 8 as a result of a defect in the coalescence of endothelial lined blood islands.

Acquired

Acquired coronary artery fistulas occur in 25% of cases. They are caused by:

  1. Gunshot wounds and shrapnel
  2. Stab wounds
  3. Inadvertent placement of an SVG graft to a coronary vein
  4. Secondary to large atherosclerotic coronary aneurysms
  5. As a complication of acute MI
  6. 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

  • 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. [1] 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.

Major Complications

11 patients (15%) experienced symptomatic cardiomyopathy, coronary thrombosis and MI.

Predictors of adverse outcome

Both angiographic and clinical features were predictive of adverse outcome.

  1. Angiographic predictors
    Drainage of CAF into the coronary sinus (P<0.001)
  2. Clinical predictors
    *Hyperlipidemia (P<0.001)
    *Systemic hypertension (P<0.001)
    *Older age at diagnosis (P<0.001)
    *Diabetes (P=0.05)
    *Tobacco use (P=0.006)

Long-term complications

The investigators conclude that long-term complications of CAF closure may include:

Further considerations

Long-term anticoagulation is suggested as treatment for the high-risk CAF that drain into the coronary sinus. This condition is likely to be associated with long-term morbidities after closure.

Differentiation form other Disorders

On angiography, a coronary artery fistula must be distinguished from a tumor blush, or arterial blood flow to a myxoma.

Diagnosis

Symptoms

  • 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.

Physical Examination

Heart

Laboratory Findings

Electrocardiogram

  • May show chamber enlargement

Chest X Ray

Echocardiography or Ultrasound

Treatment

Surgery and Device Based Therapy

Indications for Surgery

Surgical Outcomes

  • Most have an improvement in symptoms postoperatively.


2008 ACC/AHA Guidelines for the Management of Adults With Congenital Heart Disease (DO NOT EDIT)[2]

Coronary Arteriovenous Fistula (DO NOT EDIT)[2]

Class I
"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)"
Class III
"1. Patients with small, asymptomatic CAVF should not undergo closure of CAVF. (Level of Evidence: C)"
Class IIa
"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)"

References

  1. 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 |month= ignored (help)
  2. 2.0 2.1 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.

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