The epicardial coronary artery system consists of the left and right coronary arteries, which normally arise from ostia located in the left and right sinuses of Valsalva, respectively (see figures 104c, 104d, 104e, 104f, 104h). In about 50% of humans a "third coronary artery" ("conus artery") arises from a separate ostium in the right sinus.

The left main (LM) coronary artery ranges in length from 1 to 25 mm before bifurcating into the left anterior descending (LAD) and left circumflex (LC) branches. The LAD coronary artery measures from 10 to 13 cm in length, whereas the usual nondominant LC artery measures about 6 to 8 cm in length.

The dominant right coronary artery (RCA) is about 12 to 14 cm in length, before giving rise to the posterior descending artery(PDA)

The subepicardial coronary arteries run on the surface of the heart embedded in various amounts of subepicardial fat. Portions of the epicardial coronary arteries may dip into the myocardium ("mural artery " or "tunneled artery") and be covered for a variable length (1 to several mm) by ventricular muscle ("myocardial bridge").

Waller, B.F., MD, Schlant, R.C., MD, Anatomy of the Heart, Hurst's The Heart, 8th edition, p 84-86. (modified)

 

NONATHEROSCLEROTIC CORONARY HEART DISEASE

ARTERIOVENOUS FISTULAE OF CORONARY ARTERIES

Arteriovenous fistulae(abnormal communications) may involve the coronary arteries,the pulmonary artery or right ventricle(see images below fig1a and b:LCA to RV fistula and fig2.Coronary fistula LM-PT), as well the inferior vena cava,pulmonary veins or other vascular strictures(mediastinal vessels,coronary sinus,cavf-fig3 to right atrium).

This infrequent abnormality can affect persons of any age and is the most important hemodynamically significant coronary artery anomaly.Many are small and found incidentally during coronary arteriography,whereas others are identified as the cause of a continuous murmur,myocardial ischemia and angina,acute myocardial infarction,sudden death,coronary steal,congestive heart failure,stroke,arrhythmias,coronary aneurysm formation(rupture,emboli),or superior vena cava syndrome.

Fistulae from the right coronary artery are more common than from the left, and over 90% of the fistulas drain into the venous circulation.Most fistulas are single communications,but multiple fistulas have been identified.

The natural history of coronary fistulas is variable,with periods of stability in some and sudden onset or gradual progression of symptoms in others.Spontaneous closure is uncommon.

Surgical repair of the fistula is recommended for symptomatic patients at risk for future complications(coronary steals, aneurysms,large shunts).Transcatheter embolization of the fistulas have been reported.

Direct connection between a major epicardial coronary artery and a cardiac chamber or major vessel(vena cava,coronary sinus,pulmonary artery(see attachments)
is the most common hemodynamically significant coronary artery anomaly.Myocardial ischemia has been documented in some patients with coronary artery fistulas, who have no evidence of coronary atherosclerosis.

TABLE 39-3 Causes and Associations of Coronary Artery Fistulas

I. Congenital
1. Embryonic
2. Multiple; systemic hemangioma
II. Acquired
1. Closed-chest ablation of accessory pathway . Percutaneous coronary balloon angioplasty
3. Hypertrophic cardiomyopathy
4. Right/left ventricular septal myectomy
5. Penetrating and nonpenetrating trauma
6. Acute myocardial infarction.
7Dilated cardiomyopathy
8. Mitral valve surgery'
9. "Sign" of mural thrombus
10. Tumor
11. Permanent pacemaker placement. Cardiac transplant
13. Endomyocardial biopsyK
14. Coronary artery bypass grafting

 

 

cavf-Fig.1a.jpg:LCA(Left Coronary Artery to RV(Right Ventricle)Fistula

 

 

 

 

cavf-Fig.1b.jpg:Different view of Fig.1a above.

 

 

 

cavf-Fig2.jpg:Coronary Fistula LM-PT:Diagram showing coronary fistula connecting pulmonary trunk and left anterior descending(LAD)artery.It originally was misdiagonsed as an anomalous coronary.LADD.diagonal branch of LAF;LC,left circmflex;;Lm,left main:R,right.Waller.B.F.,The Heart,Hurst's,10th Edition,Page 1174

 

 

 

 

 

cavf-Fig.3 cavf.jpeg: Coronary Arteriovenous Fistula on Coronary Angiography.
A large coronary arteriovenous fistula can be seen originating in the left coronary artery, coursing over the lateral and posterior walls of the left ventricle, and eventually emptying into the right atrium. The solid arrow indicates the origin of the fistula (not well visualized), and the open arrow indicates a normal-sized left anterior descending coronary artery, which is of much smaller caliber than the greatly dilated fistula. Patients with such fistulas often have loud continuous cardiac murmurs and may have congestive heart failure, myocardial ischemia (due to a coronary-artery "steal" phenomenon), and pulmonary hypertension. Coronary arteriovenous fistulas typically arise as congenital anomalies. With obliteration of the fistula by suturing, the prognosis is usually excellent.http://content.nejm.org/cgi/content/full/331/19/1265