Asian Cardiovasc Thorac Ann 2002;10:339-341
© 2002 Asia Publishing EXchange Pte Ltd
Noninvasive Diagnosis of Coronary Artery Fistula After Cardiac Surgery
Abdullah A Alabdulgader, MRCP
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Prince Sultan Cardiac Center Riyadh, Saudi Arabia
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For reprint information contact: Abdullah A Alabdulgader, MRCP Tel: 966 3 575 0000 Ext. 1237 Fax: 966 3 575 5150 email: kidsecho{at}37.com Department of Pediatrics, King Fahad Hospital, Hofuf, P.O. Box 9596, Al Hassa 31982, Saudi Arabia.
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ABSTRACT
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A 5-year-old boy underwent ventricular septal defect closure as well as resection of the muscle bundle of a double-chamber right ventricle and a subaortic membrane. Five days after surgery, echocardiography revealed a left anterior descending artery fistula with 2 sites of entry to the right ventricle. The child was asymptomatic with no murmurs. Echocardiography is an excellent tool for detecting such silent clinical lesions.
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INTRODUCTION
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Coronary artery fistula (CAF) is an abnormal passage between the coronary artery and one of the cardiac chambers or one of the vessels around the heart. Congenital CAF is a rare anomaly, found in 1 in 50,000 patients with congenital heart disease and in 1 in 500 patients undergoing coronary angiography.1 The acquired form of the disease is thought to be much rarer, with a few isolated cases reported in the literature.2 Clinical silence with absence of symptoms and murmurs as well as electrocardiographic absence of ischemia are characteristic of acquired CAF. As early risk stratification is essential, echocardiography is an excellent tool for detecting the lesion.
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CASE REPORT
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A 5-year-old boy was diagnosed to have a ventricular septal defect (VSD), double-chamber right ventricle (DCRV), and subaortic membrane (with a gradient of 25 mm Hg). Preoperative assessment included history, physical examination, chest radiography, electrocardiography, echocardiography, and cardiac catheterization. Under cardiopulmonary bypass and 28ºC blood cardioplegia, he underwent resection of the muscle bundle of the DCRV, resection of the subaortic membrane via the VSD, and finally closure of the VSD.
The postoperative period was uneventful apart from transient urinary retention, which eventually resolved. Cardiac evaluation revealed absence of murmurs with stable hemodynamics. The electrocardiogram showed sinus rhythm at a rate of 100 beats.min-1, bifascicular block, but no evidence of myocardial ischemia. Echo-cardiographic evaluation documented successful surgical repair with no residual shunt or gradient, but it revealed fistulous communication between the left anterior descending artery (LAD) and the right ventricle (RV) through 2 entry sites at the ventricular septum. The origin of the LAD is dilated and tortuous, with color Doppler showing mosaic flow (Figure 1
). The 1st entry site was located at the inlet portion of the ventricular septum just beneath the septal leaflet of the tricuspid valve (Figures 2A and 2B). Pulsed Doppler of this passage showed continuous flow with diastolic accentuation (Figure 2C). The 2nd entry site was at the mid-ventricular septum (Figure 3).
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Figure 1. Mosaic color Doppler echocardiogram showing a dilated fistula arising from the origin of the left anterior descending artery. MPA=main pulmonary artery, PA=pulmonary artery, RV=right ventricle.
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Figure 3. Entry site of the 2nd fistulous communication at the mid-ventricular septum. LA=left atrium, LV=left ventricle, RA=right atrium, RV=right ventricle.
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DISCUSSION
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While the persistence of embryonic coronary sinusoids is thought to be the cause of congenital CAF, the acquired form is attributed to a localized inflammatory process or local injury.3 Absence of murmurs is thought to be characteristic of acquired CAF. There seems to be a greater tendency for acquired CAF to appear after right ventricular surgery. The availability of soft echo enhancement with superior harmonic imaging technology has made it possible to accurately visualize these fistulous communications. With the color flow mapping technique, large spatial areas of the cardiac chambers and vessels can be investigated at the same time. With these technical advances, the importance of pulsed Doppler for detecting CAF should diminish considerably. Conceivably, its role in confirming the classical flow pattern of CAF (as seen in Figure 2C
), after the fistula has been localized by the more efficient, time-saving color flow mapping, is still valid.
Urcelay and colleagues2 reported detecting 20 CAFs in 16 patients after RV myotomy, myomectomy, or both. In all cases, the CAFs were silent with no diastolic or continuous murmur detected by echocardiography. In our patient, 5 days after operation for VSD, DCRV, and subaortic membrane, a tortuous, dilated LAD fistula to the RV was found. The boy was asymptomatic with no murmurs or evidence of ischemia. A small initial passage with a small left-to-right shunt and the absence of coronary artery steal may explain this presentation.
We postulate that the natural course of such lesions is similar to that of congenital lesions, with the emergence of symptoms, murmurs, and myocardial ischemia as the fistula enlarges with time. The physiology of the CAF varies according to the site of termination of the fistula.4 In our patient, post-tricuspid left-to-right shunt was evident. Most cases of congenital CAF involve the right atrium, RV, or coronary sinus. In rare cases, the coronary artery drains into a large dilated chamber that has the appearance of a 5th cardiac chamber. The drainage site is the RV in most reported cases. The fact that the lower-pressure chamber is the drainage site led to the suspicion of the presence of CAF prior to surgery. Corrective surgery may create a pressure gradient, which unmasks these anomalous communications. Diastolic accentuation on pulsed Doppler indicates greater flow during this phase of the cardiac cycle, which is consistent with the flow pattern of CAF. Mechanical trauma in the form of disruption or incision of coronary arterial branches has been suggested as a possible mechanism for the development of CAF. The presence of an entry site at the myotomy or myomectomy area may support this theory.
Two-dimensional Doppler and color Doppler have been found to be excellent tools for accurately delineating these clinically silent lesions. Complications such as congestive heart failure, fistula rupture, infective endocarditis, myocardial infarction, aneurysm formation, and death are consequences that can be prevented by early diagnosis. A comprehensive review of congenital CAF in children led to the recommendation of early ligation of these fistulas because of the high incidence of infectious and ischemic complications.5 Treatment options available include transcatheter coil embolization and surgical closure of the lesion. The widespread utilization of ultrasound technology, particularly color Doppler echocardiography, as well as greater awareness of the development of such lesions and their peculiarity to RV surgery should increase the rate of diagnosis and the reported incidence of CAFs. As the natural course of these lesions is not well known, regular follow-up with echocardiographic evaluation, especially RV volume and function, is critical.
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Acknowledgments
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I would like to extend my sincere thanks to Faridah Alhazmy, pediatric echocardiographer of Prince Sultan Cardiac Center, for producing the illustrations.
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REFERENCES
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- Wenger NK. Rare causes of coronary artery disease. In: Hurst JW, editor. The heart. New York: McGraw-Hill, 1978.
- Urcelay G, Ludomirsky A, Vermilion RP, Serwer GA, Mosca RS, Bove EL. Acquired coronary artery fistulae after right ventricular myotomy and/or myomectomy for congenital heart disease. Am J Cardiol
1995;75:408–11.[Medline]
- Cheng TO, Adkins PC. Traumatic aneurysm of left anterior descending coronary artery with fistulous opening into left ventricle and left ventricular aneurysm after stab wound of chest. Report of case with successful surgical repair. Am J Cardiol
1973;31:384–90.[Medline]
- Swensson RE, Sahn DJ, Valdes-Cruz LM, Chung KJ, Sherman FS, Elias W, et al. Left coronary artery to right ventricular fistula after total repair for tetralogy of Fallot. Am J Cardiol
1987;59:713–4.[Medline]
- Liberthson RR, Sagar K, Berkoben JP, Weintraub RM, Levine FH. Congenital coronary arteriovenous fistula. Report of 13 patients, review of the literature and delineation of management. Circulation
1979;59:849–54.[Abstract/Free Full Text]
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ABSTRACT
INTRODUCTION
