Image of the Month August 2019 – An unusual cardiac connection…

An unusual cardiac connection…

 

Dr Alexia Farrugia, Dr Ermanno Capuano

 

The Essex Cardio-Thoracic Centre, Basildon University Hospital, Nether Mayne, Basildon SS16 5NL

 

A 68 year old non-smoking lady was referred to cardiology clinic in view of breathlessness on exertion, which was stable for the past few months. In view of this, an echocardiogram was requested. This showed a tortuous right coronary artery (RCA) and a vascular extra-cardiac structure was seen passing inferiorly. The left ventricle was normal in size and wall thickness and had good systolic function with an ejection fraction of 65% (by the bi-plane method). There were no regional wall motion abnormalities at rest. Diastolic filling pattern indicated impaired relaxation (Grade 1). She had mild aortic regurgitation, trivial mitral regurgitation and trivial to mild tricuspid regurgitation. In view of the vascular structure seen to pass inferior to the heart, a CT coronary angiogram was requested for further evaluation. This showed a tortuous dilated RCA which did not lie within the atrio-ventricular groove. This vessel was seen to give off branches leading into clusters of tiny vessels within the left atrio-ventricular groove and also within the surrounding coronary sinus. There was no connection of the RCA to the coronary sinus. The RCA was then seen to drain via a small tubular channel into the posterior aspect of the left ventricle, below and lateral to the mitral annulus. The diagnosis of a RCA fistula draining into the left ventricle was made. The left ventricle was of normal dimensions on a single diastolic frame and there were no signs of pulmonary hypertension.

Figure 1: Tortuous, ectatic right coronary artery and its branches visualised at the base of the heart

ectatic right coronary artery

Figure 2: Dilated acute marginal (anterior) and posterior descending (lying in the interventricular groove) arterial branches

Dilated acute marginal (anterior) and posterior descending (lying in the interventricular groove) arterial branches

Figure 3: Dilated RCA seen to fistulate into the left ventricle posteriorly

Figure 4: Tortuous dilated RCA draining into the left ventricle posteriorly, below the level of the mitral valve

Figure 5: 3D volume-rendered image of the dilated RCA – LV fistula

3D volume-rendered image of dilated RCA – LV fistula

Questions:

 

  1. What is the prevalence of coronary arteriovenous fistula (AVF) in the general population? (one correct answer)

 

  1. 5%
  2. 2%
  3. 1%
  4. 01%
  5. 002%

 

The correct answer is e. 0.002%.

These are very rare anomalies. Coronary AVFs are visualised in nearly 0.25% of patients undergoing cardiac catheterisation. They constitute nearly 50% of all coronary artery anomalies. However, they are the most common of the haemodynamically-significant coronary lesions.

 

  1. What associated anomalies may occur in conjunction with coronary AVFs? (more than one answer may be correct)

 

  1. Atrial septal defect
  2. Tetralogy of Fallot
  3. Patent ductus arteriosus
  4. Ventricular septal defect
  5. Pulmonary atresia

 

All the above answers are correct. Coronary AVFs are associated with other congenital heart disease in 20-45%. Isolated coronary AVFs occur in 55-80% of cases. The association between Down’s syndrome and ventriculocoronary fistula has also been reported in a few cases.

 

  1. Which is the most common coronary artery for a fistula to arise from and which is the most common drainage site? (one correct answer)

 

  1. Right coronary artery draining into the left ventricle
  2. Right coronary artery draining into the right ventricle or atrium
  3. Left anterior descending artery to the pulmonary trunk
  4. Left circumflex artery draining into the right ventricle
  5. Left anterior descending artery to the right ventricle

 

The correct answer is b. Right coronary artery draining into the right ventricle or atrium. The right coronary artery (or any of its branches) is the most common site of coronary AVFs accounting for 55%. More than 90% of fistulas drain into the venous structures of the cardiac circulation namely right-sided chambers, pulmonary artery, coronary sinus and superior vena cava. The commonest site of drainage is the right ventricle (40%). Coronary artery fistulae that drain into the right side of the heart are associated with more symptoms when compared to similar-sized coronary AVFs draining to the left side. The majority of patients presenting in their early 20s / 30s often present with exertional dyspnoea or angina due to coronary artery steal.

 

References:

 

Ata Y, Turk T, Bicer M, Yalcin M, Ata F, Yavuz S. Coronary arteriovenous fistulas in the adults: natural history and management strategies. J Cardiothorac Surg. 2009;4:62. Published 2009 Nov 6. doi:10.1186/1749-8090-4-62

 

Nagiub M, Mahadin D, Gowda S, Aggarwal S. Prenatal diagnosis of coronary artery fistula: a case report and review of literature. AJP Rep. 2014;4(2):e83-6.

 

Villa AD, Sammut E, Nair A, Rajani R, Bonamini R, Chiribiri A. Coronary artery anomalies overview: The normal and the abnormal. World J Radiol. 2016;8(6):537-55.

 

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