Elsevier

Cardiovascular Pathology

Volume 24, Issue 3, May–June 2015, Pages 141-148
Cardiovascular Pathology

Review Article
Coronary artery fistula: a review

https://doi.org/10.1016/j.carpath.2014.01.010Get rights and content

Abstract

Coronary arterial fistulas are abnormal connections between the coronary arteries and the chambers of the heart or major thoracic vessels. Although first described in 1841, the true incidence is difficult to evaluate because approximately half of the cases may be asymptomatic and clinically undetectable. This review will discuss the history and prevalence of coronary artery fistulas and their morphology, histology, presentation, diagnosis, treatment options, and complications.

Section snippets

History and prevalence

As the aorta exits the left ventricle, two coronary arteries originate from its root to supply the muscle and tissues of the heart. The left coronary artery originates from the left aortic sinus, whereas the right coronary artery originates from the right aortic sinus. As the right coronary artery descends it branches to give a sinuatrial nodal branch, right marginal branch, and a posterior interventricular branch. On the other hand, the left coronary artery descends and gives an anterior

Morphology

While the exact percentage of morphological origins and terminations of coronary artery fistulas differ, the consensus is that fistulas are typically found on the right side of the heart. Studies show that the point of origin in 52–60% of coronary artery fistulas is the right coronary artery, 30% at the left anterior interventricular (left anterior descending) artery, and 18% at the left circumflex artery [2], [13], [14]. Regardless of point of origin, nearly 90% of fistulas drain to the right

Histology

In order to study the histology of coronary artery fistulas, Neufeld et al. removed a segment of the parent coronary artery involved in a fistula that terminated in the right ventricle. Microscopic analysis showed that most of the vessels studied had prominent muscle bundles and contained a duplicated internal elastic lamina dispersed between them. Additionally, the tunica intima layer had nonspecific fibrous thickening [17], [20]. A similar study also reported the same histological changes in

Presentation and symptoms

Typically coronary artery fistulas are often asymptomatic during childhood. Based on several studies, symptoms are present in 19–63% of patients, with the majority occurring after 18 years of age [4], [21], [22]. The most common symptom reported is dyspnea, with exertion [4], [21]. Murmurs are also commonly reported with coronary artery fistulas; in fact, many otherwise asymptomatic fistulas are often found after angiographic investigation of continuous murmurs heard at the lower left sternal

Pathophysiological consequences

According to Ata et al. [33], coronary artery fistulas are a very rare cardiac anomaly; however, they are the most hemodynamically significant lesions affecting the cardiovascular system. Ata et al. [33] states that approximately half of all CAF patients are asymptomatic and some congenital fistulas may spontaneously regress during childhood [33]. In patients with symptoms, most report atypical chest pain and exertional dyspnea that is often due to the progressive enlargement of the fistula and

Complications

Though the majority of coronary artery fistulas are etiologically congenital, complications typically do not present until after age 20 years [37]. These complications display a wide range in severity, from being asymptomatic in 75% of cases to presenting with myocardial ischemia and aortic insufficiency [23], [38], [39]. Symptoms, when present, are usually secondary to congestive heart failure, which, in turn, is as a result of a left-to-right shunt. Arrhythmias can also occur due to excessive

Diagnostics

Due to the asymptomatic nature of coronary artery fistulas, many are incidental findings during routine examinations. The gold standard for identifying them remains coronary angiography; however, less invasive two- and three-dimensional imaging techniques are becoming more common [41], [42], [43], [44]. The benefit of coronary angiography is that it helps to determine which coronary artery is involved in the fistula. Based on this, it can help to identify the communicating chamber or vessel and

Pediatric

In a retrospective study, Mavroudis et al. reviewed the diagnosis and treatment of pediatric coronary artery fistula patients. As in the general population, most of the pediatric patients were asymptomatic and the majority of fistulas were congenital. Only one of the patients studied had an acquired fistula as a consequence of tetralogy of Fallot repair. In addition to tetralogy of Fallot, other cardiac anomalies that present in the pediatric patient cohort were patent arterial duct and atrial

Prenatal

Coronary artery fistulas account for 50% of pediatric coronary vascular aberrations and are believed to originate from the thebesian vessels [4], [7]. During prenatal life, the coronary arteries communicate with the ventricles via intratrabecular spaces. As the fetus develops, these intratrabecular spaces become sinusoids that communicate between the coronary arteries and veins and the chambers of the heart. Fistulas are thought to develop if these intratrabecular spaces do not close to

Treatment

Due to the fact that CAF mostly remain asymptomatic, the treatment of CAF is essentially medical; conservative management with continued follow up [71]. While rare, there have been cases of spontaneous closure of coronary artery fistulas without surgical or catheter repair [4], [72], [73], [74]. Among these, most spontaneous closures occur in children diagnosed with a coronary artery fistula prior to 2 years of age, and these fistulas almost always drain into the right ventricle [75]. Surgical

Surgical correction

In coronary artery fistula patients where operative correction proves necessary, surgical ligation or percutaneous transcatheter occlusion are possible treatment options [43], [66], [79], [80]. The type of operative correction for coronary artery fistulas depends on the location of the fistula, the coronary artery involved, and the termination of the connection. Typically, direct ligation of the fistula at the drainage site is preferred because it should eliminate the possibility of myocardial

Transcatheter techniques

Studies suggest that transcatheter approaches are more beneficial than surgical approaches for eligible coronary artery fistula cases. Transcatheter techniques do not require median sternotomy or cardiopulmonary bypass, thus limiting potential iatrogenic complications. Transcatheter closure is also a less expensive procedure with decreased morbidity, decreased recovery time, and better cosmetic results [43], [83], [84]. On the other hand, the use of transcatheter approaches and coil occlusion

Management

Luo et al. suggest that there is potential for thrombotic events that may lead to myocardial infarctions after coronary artery fistula closure. Prophylactic low-dose aspirin is suggested in such cases. In large postoperative coronary artery dilations, anticoagulant therapy such as warfarin is recommended [4]. Angina secondary to coronary artery fistula is managed according to the standard-of-care guidelines for angina medical management. As such, beta-blockers, calcium channel blockers, and

Conclusion

Coronary artery fistulas, while rare, are pathophysiologically important and should be included in the differential diagnosis of cardiac-associated pathologies. Proper recognition, imaging, diagnosis, treatment, and symptom management can prevent potentially deadly cardiac complications associated with these anomalous communications. This review highlights the best imaging and treatment techniques for coronary artery fistulas, along with information describing the prevalence for both adult and

Acknowledgments

The authors wish to thank Jessica Holland, MS, Medical Illustrator at St. George's University, Grenada, West Indies, for the creation of her illustrations used in this publication.

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