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 Table of Contents  
CASE REPORT
Year : 2022  |  Volume : 10  |  Issue : 3  |  Page : 160-164

Peculiar association of a small coronary arteriovenous fistula with inferior wall myocardial infarction: A bystander or culprit?


Department of Cardiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India

Date of Submission21-Jun-2022
Date of Decision03-Sep-2022
Date of Acceptance05-Sep-2022
Date of Web Publication14-Dec-2022

Correspondence Address:
Ankit Kumar Sahu
Department of Cardiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow - 226 014, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/heartindia.heartindia_28_22

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  Abstract 


Coronary arteriovenous fistula (CVAF) is usually an asymptomatic, incidental finding observed in 0.1%–0.2% of patients undergoing coronary angiography. Myocardial infarction (MI) secondary to a CVAF has been rarely reported. We herein describe a case of a young male presenting with acute inferior wall MI without any underlying cardiovascular risk factors and normal coronaries except for the presence of a small CVAF arising from the proximal right coronary artery. This report deliberates on the possibility of this fistula being an incidental finding as a bystander or as a culprit in this special clinical scenario, after careful exclusion of other possible nonatherosclerotic etiologies.

Keywords: Coronary arteriovenous fistula, culprit vessel, myocardial infarction


How to cite this article:
Dadarwal A, Kapoor A, Sahu AK. Peculiar association of a small coronary arteriovenous fistula with inferior wall myocardial infarction: A bystander or culprit?. Heart India 2022;10:160-4

How to cite this URL:
Dadarwal A, Kapoor A, Sahu AK. Peculiar association of a small coronary arteriovenous fistula with inferior wall myocardial infarction: A bystander or culprit?. Heart India [serial online] 2022 [cited 2023 Feb 2];10:160-4. Available from: https://www.heartindia.net/text.asp?2022/10/3/160/363536




  Introduction Top


Coronary arteriovenous fistula (CVAF) is the most frequent congenital coronary anomaly disorder comprising 14% of all congenital coronary abnormalities (0.2%–0.4% of all congenital cardiac defects). Approximately half of these fistulas arise from the right coronary artery (RCA), 45% from the left coronary artery (LCA), and 5% have a dual coronary connection.[1] Most of them being asymptomatic, their detection is suspected by the presence of a continuous murmur. However, their presence is sometimes complicated by myocardial ischemia, congestive heart failure, sudden cardiac death, infective endocarditis, aneurysm formation, and thrombosis.[2],[3],[4],[5] Coronary steal, vasospasm, distal embolization, ulceration, and rupture are the proposed mechanisms leading to myocardial ischemia in patients with culprit vessel CAVF. This case report illustrates the confusion regarding the exact nature of the co-existence of this anomaly in the given specific clinical scenario as to whether it is a bystander or a culprit.


  Case Report Top


A 34-year-old young, apparently healthy, male athlete without any cardiovascular (CV) risk factors presented elsewhere with acute onset severe retrosternal resting chest pain that subsided by sublingual nitroglycerin. On evaluation, troponin-I was elevated and 12 lead electrocardiogram (ECG) showed ST elevation in inferior leads with reciprocal ST depression in lead I and aVL, suggestive of inferior wall STEMI [Figure 1]a. Dual antiplatelet, high-intensity statins, and antianginal therapy were initiated and the patient was referred to our PCI-enabled center for coronary angiography and possible revascularization. Meanwhile, on the 5th day of presentation at our hospital, the patient remained largely asymptomatic on mild physical exertion devoid of any postmyocardial infarction (MI) angina. Physical examination was unremarkable. Serial ECG assessment revealed dynamic evolution of ischemic changes in the form of settlement of ST-segment elevation, development of new Q waves, loss of R-wave amplitude, and T inversion in inferior leads [Figure 1]b. Biochemical laboratory tests revealed a normal serum lipid profile, renal function, and hemogram. Transthoracic echocardiography, however, did not show any evidence of regional wall motion abnormality or left ventricular dysfunction. Pulmonary artery pressures were normal with no valvular regurgitation or chamber dilatation.
Figure 1: Upper panel (a) shows initial 12-lead ECG after onset of chest pain having ST-segment elevation in inferior lead (down solid arrow) with reciprocal ST depression in I, aVL (down hollow arrow); while bottom panel ECG (b) done prior to coronary angiography shows pathological Q wave and T inversion in inferior leads suggestive of evolved inferior wall MI. ECG: Electrocardiogram, MI: Myocardial infarction

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Coronary angiography was done to delineate coronary anatomy and identify the underlying vascular pathomorphology of the culprit lesion. Coronaries had normal origin and course with the right dominant system. TIMI III flow and normal TIMI frame counts for RCA, left anterior descending artery (LAD), and left circumflex artery were noted without any evidence of a filling defect, luminal narrowing, dissection flap, or vasospasm [Videos 1 and 2 [Additional file 1] [Additional file 2]]. RCA injection showed the simultaneous entry of contrast in a narrow tubular tract connected to proximal RCA, coursing posterosuperiorly and finally opening into right atrium with smoke-like accumulation being rapidly washed out which was confirmed in multiple views [[Figure 2], [Figure 3] and Videos 3, 4 [Additional file 3] [Additional file 4]]. The connection of the tract to RCA seems to be stenosed at the proximal end. Furthermore, a vena comitans accompanying the conal branch is draining into the fistulous tract [Video 5 [Additional file 5]]. An additional arteriovenous connection is seen to empty into a marginal vein which finally drains into the coronary sinus. Coronary computed tomography (CT) angiography was performed to define in detail the origin, anatomical course, and the drainage chamber of this fistula which showed a small fistulous tract originating near the RCA ostium draining into the right atrial appendage [Figure 4]. Hence, a diagnosis of MI with nonobstructive coronary arteries was made. Furthermore, the occurrence of recent MI with clean coronaries in a physically active, apparently healthy young person without any underlying CV risk factors, leads to speculation about the pathophysiological role of accompanying CAVF by virtue of its proximity to RCA ostium in causing inferior wall STEMI.
Figure 2: Upper panel shows RCA angiogram in RAO view showing fistulous tract (down arrow) formed by conal branch (rightward arrow) and accompanying vena comitans (upward arrow) finally draining into right atrial appendage (a) with narrowing in the proximal part (b). Another fistula (leftward arrow) is seen draining into coronary sinus (asterisk). Bottom panel (c) depicts the pictorial representation of fistula's anatomy as seen in RAO view. RCA: Right coronary artery, RAO: Right anterior oblique

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Figure 3: (a) RCA angiogram in LAO view showing fistulous tract (upwards arrow) draining into right atrial appendage (asterisk). (b) Depicts the pictorial representation of fistula's anatomy as seen in LAO view. RCA: Right coronary artery, LAO: Left anterior oblique

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Figure 4: (a) axial scans of MDCT angiocardiogram marking the origin of RCA from right coronary sinus (leftward arrow) and narrow fistulous tract (straight line) communicating with right atrium. (b) Similar findings in right oblique sagittal view. (c) 3D volume rendered image depicting origin of fistula from RCA, its course and termination into RA. MDCT: Multidetector computed tomography, RCA: Right coronary artery, 3D: Three-dimensional, RA: Right atrium, RAA: Rright atrial appendage, LA: Left atrium, Ao: Sinus of Valsalva at the level of RCA origin, AVF: Arterio-venous fistula

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The patient was kept on medical therapy after counseling and remained quite asymptomatic at 1-year follow-up with resumption of his daily physical activities.


  Discussion Top


In a CAVF, the right and LCA arise from their appropriate sinuses but a fistulous branch of one or more than one drains into a cardiac chamber, the pulmonary trunk, coronary sinus, vena cava, or pulmonary vein. The drainage site of a coronary artery is more important than its origin and consists of a single vascular channel, multiple channels, or maze of fine channels that form a diffuse network or plexus. Majority (>90%) of CAVF drain into the right side of the heart namely right ventricle (40%), right atrium (25%), pulmonary artery (15%), coronary sinus (7%), and rarely vena cava or hepatic vein.[2],[6],[7] Rarely, CAVF communicates with left heart structures namely left atrium (5%), left ventricle (3%), and rarely pulmonary veins.[3] Some of the CAVF complications affecting coronaries are coronary artery dilatation, aneurysm formation, intimal ulceration, medial degeneration, intimal rupture, atherosclerotic deposition, calcification, side-branch obstruction, mural thrombosis, and rupture.

The physiologic implications of CAVF depend on the volume of blood flowing through them (Qp/Qs), the drainage chamber or vascular bed, and the myocardial ischemia resulting from coronary steal caused by low-resistance vascular channels. Acquired stenosis distal to CAVF aggravates perfusion deficit because the fistula acts as a low-resistance alternative to the acquired obstruction. MI due to CAVF per se is rare (<5%). In few cases reporting anterior wall MI with co-existing LAD to the left ventricular fistula without obstructive stenosis of LAD, it has been proposed that coronary steal and thrombosis could have been led to the AWMI.[8]

Prima-facie, CAVF in our patient could easily be written off as an incidental finding first due to a lack of evidence of a preexisting coronary steal phenomenon causing myocardial ischemia, and second the fistula being hemodynamically nonsignificant. However, the fact that the artery of CAVF origin was the infarct-related artery in our case draws our attention whether it is a bystander or a culprit in this clinical scenario. Since the shunt through fistula was small therefore the flow itself cannot lead to coronary steal causing significant myocardial ischemia. Nonetheless, as the origin of the fistula was near the RCA ostium, it is a possibility that this site of turbulence could have led to intimal tear, ulceration, and thrombus formation [Figure 5]. Furthermore, the close vicinity of CAVF origin and RCA ostium could have provided a get-away to the above-formed thrombus thereby explaining the transient abortive clinical course of inferior wall STEMI thus caused. Among the various nonatherosclerotic etiologies for MI, the most notable ones are congenital coronary artery anomalies, spontaneous coronary artery dissection, coronary vasospasm, septic embolism from infected valve, and paradoxical embolism from right to left shunt. In our case, even though there was no clinical clue and imaging findings suggestive of the above causes (except finding of CVAF) nevertheless, meticulous workup was done for each of the above causes including for hypercoagulable state.
Figure 5: Sketch showing proposed hemodynamic and vascular mechanisms in the presence of coronary arterio-venous fistula leading to an acute coronary event

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2008 ACC/AHA guidelines recommend percutaneous or surgical closure for large CVAF regardless of symptoms and for small-to-moderate size fistulae with evidence of myocardial ischemia, arrhythmia, ventricular dysfunction, ventricular enlargement, or endarteritis.[9] In addition, closure of fistulae arising from the proximal segment of the coronary artery is also recommended as there is a likelihood of aneurysm formation with a high possibility of rupture. Transcatheter closure is indicated when the anatomy of the fistula is favorable namely nontortuous vessel and a narrowed distal end of fistula to avoid embolism in the drainage chamber.[10] The choice of device and technique depends on the anatomic characteristics of CAVF (i.e. catheter size, the size of the feeder vessel, and tortuosity of the catheter course to reach the intended point of occlusion). Surgical treatment is reserved for single, large, symptomatic fistulae, multiple communications, extremely tortuous pathways, aneurysm formation, or need for a simultaneous distal bypass.

However, as we could not establish direct evidence of a link between CAVF and MI, in our case, we decided to keep the patient on medical follow. On routine outpatient follow-up visits, he remained asymptomatic with good functional capacity without any evidence of inducible myocardial ischemia on exercise stress testing.


  Conclusion Top


Acute coronary syndrome presentation in a young, physically active person without any underlying CV risk factors and angiographically normal coronaries should be meticulously investigated for nonatherosclerotic pathologies. Although small CVAF is considered inconsequential entities in a patient with an acute coronary syndrome, sometimes under specific clinical scenario they may provide an explanation for the occurrence of the event. More experimental research is warranted to lucidly decipher their pathophysiological mechanisms for unexplained relevant clinical event as in our case with MI.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his consent for images and other clinical information to be reported in the journal. The guardian understands that names and initials will not be published and due efforts will be made to conceal patient identity, but anonymity cannot be guaranteed.

Ethical approval

IEC approval not obtained as this study is a case report involving a single patient.

Authors' contributions

All authors read and approved the final manuscript.

Anurodh Dadarwal: Acquired the data and prepared the rough draft.

Ankit Kumar Sahu: Refined the draft; did data interpretation and draft designing.

Aditya Kapoor: Played an important role in concept and planning of the case report.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Duerinckx AJ, Perloff JK, Currier JW. Arteriovenous fistulas of the circumflex and right coronary arteries with drainage into an aneurysmal coronary sinus. Circulation 1999;99:2827-8.  Back to cited text no. 1
    
2.
Stansel HC Jr., Fenn JE. Coronary arteriovenous fistula between the left coronary artery and persistent left superior vena cava complicated by Bacterial endocarditis. Ann Surg 1964;160:292-6.  Back to cited text no. 2
    
3.
Cheng TO. Left coronary artery-to-left ventricular fistula: Demonstration of coronary steal phenomenon. Am Heart J 1982;104:870-2.  Back to cited text no. 3
    
4.
Lau G. Sudden death arising from a congenital coronary artery fistula. Forensic Sci Int 1995;73:125-30.  Back to cited text no. 4
    
5.
Habermann Jh, Howard Ml, Johnson Es. Rupture of the coronary sinus with hemopericardium. A rare complication of coronary arteriovenous fistula. Circulation 1963;28:1143-4.  Back to cited text no. 5
    
6.
Ogden JA. Congenital anomalies of the coronary arteries. Am J Cardiol 1970;25:474-9.  Back to cited text no. 6
    
7.
Gorgulu S, Nurkalem Z, Eren M. Right coronary artery hepatic vein fistula: A case report. Echocardiography 2006;23:869-71.  Back to cited text no. 7
    
8.
Kurt IH. Myocardial infarction caused by a fistula between the left anterior descending coronary artery and the left ventricle. Tex Heart Inst J 2009;36:177-9.  Back to cited text no. 8
    
9.
Warnes CA, Williams RG, Bashore TM, Child JS, Connolly HM, Dearani JA, et al. ACC/AHA 2008 guidelines for the management of adults with congenital heart disease: Executive summary: A report of the American College of cardiology/American heart association task force on practice guidelines (writing committee to develop guidelines for the management of adults with congenital heart disease). Circulation 2008;118:2395-451.  Back to cited text no. 9
    
10.
Harris WO, Andrews JC, Nichols DA, Holmes DR Jr. Percutaneous transcatheter embolization of coronary arteriovenous fistulas. Mayo Clin Proc 1996;71:37-42.  Back to cited text no. 10
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]



 

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