# Iatrogenic Aortocoronary Arteriovenous Fistula following Coronary Artery Bypass Surgery: A Case Report and Complete Review of the Literature

Authors: Jonathan D. Gardner; William R. Maddox; Joe B. Calkins
Journal: Case Reports in Cardiology
 (2012)

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## Abstract

The case of a patient who presented with angina following a coronary artery bypass (CABG) operation during which the left internal mammary artery was inadvertently anastomosed to a cardiac vein is presented. The literature concerning previously reported cases of aortocoronary arteriovenous fistulas (ACAVF) due to inadvertent grafting of a coronary vein is reviewed and the significance of this complication is discussed. ACAVF due to inadvertent grafting of a coronary vein is a rare complication of CABG and may be a more common cause of graft failure than has previously been recognized. Distortion of cardiac anatomy, the presence of epicardial fat, and an intramyocardial course of the artery intended for grafting are predisposing factors. Some patients present with angina pectoris and heart failure whereas others have no symptoms. The diagnostic test of choice is coronary angiography. Cardiac MRI and CT have a limited role due to the smaller size and the more clearly defined course of these fistulas. Asymptomatic patients are simply observed since spontaneous closure of these fistulas is reported. Symptomatic patients can be treated with combined medical management and percutaneous methods.


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## Body

## 1. Introduction

Iatrogenic aortocoronary arteriovenous fistula (ACAVF) resulting from placement of an arterial graft to a cardiac vein is a rare complication of CABG. We present a case involving grafting of the left internal mammary artery (LIMA) to a left coronary vein and a review of the literature.


## 2. Patient Presentation

The patient is a 69-year-old male with hypertension, hyperlipidemia, and type 2 diabetes mellitus who presented with exertional chest pain, dyspnea, decreased functional capacity and occasional palpitations. A myocardial perfusion study one month earlier had demonstrated inferolateral ischemia and preserved left ventricular systolic function (EF 69%).Subsequent left heart catheterization (LHC) showed 70% ostial left main stenosis (Figure1), 60% left anterior descending artery (LAD) stenosis, and complete occlusion of the mid circumflex artery with filling via right to left collaterals. The right coronary artery (RCA) had 70% stenosis in its midportion and left ventricular systolic function was normal. He underwent CABG with the following grafts: LIMA to the LAD, SVG to OM, and SVG to the PDA. Postoperative course was uncomplicated.Figure 1
Left anterior oblique view of the left coronary artery. A JL4 catheter is seen engaging the left coronary artery. The ostial left main is tapered and has a 70% stenosis.Three months later, the patient presented with exertional chest pain similar to his pain prior to surgery. Repeated LHC showed no change in the native coronary arteries and patent SVG to OM and SVG to PDA with good flow. Angiography of the LIMA demonstrated that it was anastomosed to a cardiac vein with resultant flow into the coronary sinus (Figure2).Figure 2
This is an angiogram of the left internal mammary artery as it anastomoses to a cardiac vein. Contrast fills the coronary sinus as it traverses the posterior atrioventricular groove.Percutaneous coronary intervention (PCI) was performed with placement of three drug eluting stents in the LM and ostial/proximal LAD. There was no residual stenosis (Figure3). Subsequently, eight 3 mm stainless steel coils were deployed in the distal portion of the LIMA just proximal to the anastomosis with the cardiac vein with resultant occlusion of the LIMA (Figure 4).Figure 3
Right anterior oblique view of the left coronary artery following left main and LAD intervention. The left main is no longer tapered and the contrast effluxes out of the left main into the left coronary cusp of the aortic valve.Figure 4
Angiogram of the deployment of the coils in the distal left internal mammary artery. The catheter is accessing the LIMA via the left subclavian artery.Six months after the intervention, the patient had a repeated myocardial perfusion study. No ischemia was demonstrated and LV systolic function was normal. He has remained asymptomatic.


## 3. Discussion

Iatrogenic ACAVF resulting from inadvertent grafting to a coronary vein is a rare complication of CABG. Only 36 cases have been reported (Table1). Deligonul et al. [24] reported two cases of ACAVF, which closed spontaneously, suggesting that this complication may be more frequent than previously thought. Symptomatic patients experiencing spontaneous closure of the ACAVF would be found to have an occluded graft and an unbypassed artery with coronary angiography. It may be unrecognized in other patients with this complication since they may remain asymptomatic or significantly less symptomatic following bypass surgery and would have no indication for coronary angiography.Table 1
Reports of inadvertent attachment of a bypass graft to a cardiac vein.
Author
Patient
Symptoms/onset after CABG
Murmur
Graft/Intended Artery/Actual Anastamosis
Shunt
Hemodynamics
CABG
Previous MI
Treatment
Vieweg [1]
53 M
CHF/6 weeks
Continuous 2nd LICS
SVG/LAD/anterior cardiac vein
Shunt by hydrogen inhalation; normal pulse ox
Mild elevation of right heart pressures
First
No
Graft removal; regrafting of SVG to LAD
Lawrie et al. [2]
44 M
Angina pectoris; <3 months
Systolic; base to neck
SVG/LAD/LAD vein
Not mentioned
Not mentioned
Third
No
Graft ligation; SVG to LAD
Treistman et al. [3]
55 M
SVT, palpitations, syncope; 3.5 years
Continuous 3rd LICS
SVG/LAD/anterior interventricular vein
Normal oximetry
Mild elevation of right heart pressures
First
Anterolateral MI
None
Klinke et al. [4]
40 M
Angina pectoris; 5 months
Not mentioned
SVG/LAD/anterior interventricular vein
Coronary sinus 02 saturation 90%
Normal
First
No
CABG
Starling et al. [5]
47 M
None reported. Anterior ischemia; 3 weeks
Continuous 2nd LICS to apex
SVG/LAD/anterior cardiac vein
None
Normal
First
Posterolateral MI
Fistula ligation; SVG to diagonal
Starling et al. [5]
66 M
Asymptomatic
Continuous 2nd and 3rd LICS to the apex
SVG/proximal LAD to distal LAD/anterior cardiac vein distal LAD
None
Normal
First
Anteroseptal MI
Observation
Grollman Jr. et al. [6]
52 M
Fatigue, dyspnea; 1 year
None
SVG/anterolateral branch of Cx/anterior interventricular vein
1.1 : 1
RVEDP 8 mmHg LVEDP 25 mmHg
First
Anteroapical MI
Percutaneous occlusion of SVG with 2 coils
Hubert et al. [7]
55 M
CHF, VT; 1 month
Continuous ULSB
SVG/LV branch of RCA PL of Cx/LV branch posterior interventricular vein
Normal oximetry
RA 20 mmHg
First
Inferior MI
Ligation of fistula
Przybojewski [8]
43 M
Angina pectoris; 10 days
Continuous 2nd and 3rd LICS
SVG/LAD/LAD vein
Not mentioned
Not mentioned
First
Anterolateral MI
Ligation; repeat CABG
Goldbaum et al. [9]
53 M
Angina pectoris, exertional dyspnea; 4 years
None
SVG/LAD/anterior interventricular vein
Small; not quantified
PA 42/19 LVEDP 19
First
Anterior MI
PTCA of LAD; percutaneous occlusion of SVG with coils
Ross and Jang [10]
44 M
Anginal pectoris; onset not mentioned
Systolic; ULSB
SVG/intermediate or Cx/left marginal vein
1.4 : 1
Normal
Second
Inferior MI
None reported
Jost et al. [11]
57 M
Angina pectoris; 2 years
Not mentioned
SVG/LAD/anterior cardiac vein
18% of pulmonary flow
Not mentioned
First
No
Embolization with silicone balloon
Graeb et al. [12]
56 F
Angina pectoris; 1 year
Not mentioned
SVG/PDA/PDV
Small
Normal
First
No
Balloon embolization of PDA (unsuccessful)
Marin-Neto et al. [13]
57 M
Dyspnea, chest pain; 1 month (no ischemia detected)
Systolic; pulmonic area
SVG/first diagonal/anterior cardiac vein
23% of pulmonary flow
Normal
First
Inferior MI
None
Marin-Neto et al. [13]
84 M
Angina pectoris; 14 months
Not mentioned
SVG/first diagonal/anterolateral coronary vein
12% of pulmonary flow
Not mentioned
First
No
PTCA of new RCA lesion, no treatment of fistula
Scholz et al. [14]
49 M
Angina pectoris 15 months
Systolic ULSB
SVG/OM1, OM2/OM1, coronary vein
Small
Normal
First
No
Observation
Calkins Jr. et al. [15]
51 F
Angina pectoris; 2-3 months
None
SVG/OM1, OM2/OM1 coronary vein
None
RV 55/15 PA 55/17
Second
No
Coil embolization
De Marchena et al. [16]
73 M
Diminished exercise capacity, dyspnea; 2 months
None
LIMA/LAD/great cardiac vein
Small
RV 68/12 RA 12 mmHg
First
No
Observation
Khunnawat et al. [17]
75 F
Dyspnea; 10 years
S3, no murmur
SVG/RCA/cardiac vein
Not mentioned
Not mentioned
First
LBBB on EKG
Not mentioned
Khunnawat et al. [17]
57 M
Dyspnea; 6 years
None
LIMA/LAD/LAD cardiac vein
Not mentioned
Not mentioned
First
Not mentioned
Not mentioned
Maier et al. [18]
50 M
Dyspnea and Angina pectoris; 2 years
Systolic murmur at ULSB
SVG/D1/coronary vein
Large left to right
Pulmonary C.O. 6.6 L/mm, systemic CO 4.8 L/mm,normal pulmonary pressures
First
Not mentioned
PTCA; failed percutaneous coil embolization led to percutaneous transcatheter detachable balloon of SVG to D1
Patterson et al. [19]
67 M
angina Pectoris; 7 months
Not mentioned
LIMA-RIMA/PL/PL vein
Present
Not mentioned
First
Not mentioned
PCI to revascularize Cx; then coil embolization of RIMA
Sheiban et al. [20]
73 M
Positive stress test and angina with exertion; 2 months
Not mentioned
LIMA/LAD/GCV
Present “arteriovenous steal” Moderate L-R Shunt
Not mentioned
First
No
PCI with DES of LAD and PCI with covered stent of GCV through coronary sinus
Hmem et al. [21]
76 M
Dyspnea, LE edema, CHF/RHF; 2 months
None
LIMA/LAD/LIMA/cardiac vein
Not mentioned
Not mentioned
First
AS Q waves
Coil embolization to proximal LIMA
Lopez et al. [22]
74 M
Rest angina; 3 months
Not mentioned
SVG-OM2-OM3/SVG-L marginal vein of OM3
No significant left to right shunt
Not mentioned
Second
Not mentioned
PCI, embolization of marginal vein
Braun et al. [23]
58 M
Angina; 6 months
Not mentioned
LIMA/LAD/LIMA/cardiac vein
Not mentioned
Not mentioned
Second
Not mentioned
RCA-PTCA; coil embolization
Deligonul et al. [24]
66 M
Asymptomatic
None
LIMA/LAD/anterior interventricular vein
Small
None
First
No
Spontaneous closure
Deligonul et al. [24]
57 M
Asymptomatic
None
LIMA/LAD/anterior interventricular vein
Small
None
First
No
Spontaneous closure
Miranda et al. [25]
66 M
Angina; 2 weeks
Not mentioned
LIMA/LAD/anterior interventricular vein
Small
Pulmonary artery pulse ox 66%
Second
No
PTCA to diagonal branch graft followed by balloon occlusion of fistula
Peregrin et al. [26]
54 M
Unstable angina; 1 year
Systolic/diastolic left parasternal
Graft/diagonal branch/graft vena cordis magna
Not mentioned
Not mentioned
First
Inferior MI
PTCA of RCA and balloon occlusion of AV fistula
Cardoso [27]
55 F
Angina
Continuous second left intercostals space
SVG/LAD/LAD vein
Aortic oxygen saturation 92%, coronary sinus saturation 80%, SVC saturation 73%
LV 171/19, RV 43/12, mean PCWP 21
First
No
Not mentioned
White et al. [28]
56 M
Angina and troponin elevation; 5 years
Not mentioned
LCX-vein graft-marginal/LCX-coronary sinus
None
None
First
No
MRI; coil embolization
Thomas et al. [29]
76 M
Angina with exertion; 3 months
Not mentioned
LIMA/LAD/AIV
Not mentioned
Not mentioned
First
Not mentioned
PCI with stenting and PCI with embolization
Mukhopadhyay et al. [30]
60 M
Exertional angina
Not mentioned
LIMA/LAD/cardiac vein
Left to right shunt
RH and PA pressures normal, 02 sat was 84% on step up in coronary sinus and 72% in the RA to 80% in PA
First
Not mentioned
PCI with failed coil embolization, deferred to surgical correction
Jung et al. [31]
50 M
Asymptomatic
Not mentioned
LIMA/LAD/GCV
Not mentioned
ECHO showed LV hypokinesis and LV systolic dysfunction.
First
Not mentioned
CT angiogram; PCI/DES and Coil embolization
Current Case
69 M
Angina with exertion left arm radiation; 3 months
None
LIMA/LAD/LIMA/cardiac vein
None
Aorta 119/54, mean 77, LV systolic: 130, LVEDP: 14, LV-angiography EF = 55%
First
No
PCI/DES and coil embolization to LIMAThis complication can result in significant morbidity by several mechanisms. Postoperative angina can occur either as a result of either residual ischemia due to an unbypassed artery or a coronary steal phenomenon. A state of high output failure can result if there is a significant degree of left-to-right shunting over an extended period of time. If left untreated, shunting can cause other complications, such as bacterial endocarditis or fistula rupture [15, 17, 19, 28, 29]. Although significant morbidity may arise, some patients remain asymptomatic and spontaneous closure of the fistula can occur [24].As this is a rare complication, predisposing factors are difficult to identify. It is reasonable to assume that anatomical distortion of the myocardium may increase the risk of iatrogenic anastomosis of a graft to a cardiac vein. The presence of scarring and fibrosis following pericardial disease, myocardial infarction (MI), or previous CABG as well as the presence of epicardial fat can make identification of the artery more difficult [15, 19, 20, 29]. Thirty-five percent of patients had a previous MI and 18% had undergone CABG. The majority of cases involved the LAD (22 patients, 61%) and its diagonal branch (4 patients, 11%), which can be deeply embedded in epicardial fat or myocardium.The majority of patients presented with angina (23 patients, 63.9%) or dyspnea (8 patients, 22.2%) (Table1). Three presented with heart failure symptoms, two with arrhythmias (VT and SVT), one with syncope, and one with diminished exercise capacity. Four were asymptomatic. No symptoms were reported for another patient who was found to have anterior ischemia on an ECG. The time of onset of symptoms following CABG was variable, ranging from 10 days [8] to 10 years [17]. No obvious trend was present concerning the onset of symptoms following CABG. Symptoms occurred in 14 patients within the first three months postoperatively and between one and 10 years postoperatively in 16 patients.The most common physical finding was a continuous or systolic murmur, followed by signs of heart failure (Table1). However, the majority of reports did not mention whether or not a murmur was present.In all of the reported cases, the standard diagnostic tool was LHC since it allows direct visualization of the ACAVF and guides percutaneous therapy. Right heart catheterization (RHC) was performed in 19 cases and demonstrated elevated filling pressures in nine patients and normal pressures in 10 (Table1).Coronary angiography can identify the origin of a coronary fistula and assess hemodynamics, but may fail to demonstrate the relation to other structures and the drainage site [32]. Cardiac MRI and CT angiography have emerged as valuable modalities to demonstrate the size, course, anatomic connection, and other anatomic features of larger and more complex congenital and acquired coronary fistulas [32, 33] and provide valuable information necessary for surgical treatment [34–38]. None of the more recently reported ACAVFs due to inadvertent grafting of a coronary vein were evaluated by MRI or CT, most likely because these fistulas are smaller and better defined and because surgical closure has been replaced by percutaneous treatments.Medical management and observation remain the treatment of choice for asymptomatic patients. Deligonul et al. [24] presented 2 cases of asymptomatic iatrogenic ACAVF, which closed spontaneously while the patients received medical management, supporting a more conservative approach to these patients. For symptomatic patients and those who are refractory to medical therapy, surgical closure of the ACAVF and grafting of the native artery have historically been preferred. With improvements in percutaneous methods, coil or balloon embolization, sometimes combined with stenting of the ungrafted artery, have become the new standard [18, 29]. In nearly half of the reported patients who were treated percutaneously (7 out of 15), the unbypassed vessel was not treated and the patient was treated with optimal medical therapy for coronary artery disease. These patients remained asymptomatic, suggesting that the shunt, rather than the unbypassed artery, might have been the underlying cause of the patients’ symptoms.Another advance in the treatment of this complication is the percutaneous approach to the ACAVF via the coronary sinus. Sheiban et al. [20] described a case in which a covered stent was deployed in the cardiac vein using this approach for the closure of an end-to-side anastomosis of the graft to the vein. Additionally, Lopez et al. [22] also used a coronary sinus approach to treat a side-to-side anastomosis of the proximal segment of a sequential graft that was anastomosed to a cardiac vein, with preservation of the distal end-to-side anastomosis to the coronary artery.


## 4. Conclusion

Iatrogenic aorto-coronary arteriovenous fistula due to inadvertent anastomosis of a bypass graft to a cardiac vein is a rare complication that is probably more common than previously believed and may be a more frequent cause of graft failure and recurrent angina following CABG. Anatomical distortion of the surface of the myocardium, the presence of epicardial fat, and an intramyocardial course of the intended artery for grafting are predisposing factors.Left heart catheterization is the diagnostic test of choice for this complication. Cardiac MRI and CTA have a more limited diagnostic role due to the smaller size of the fistula and its more easily defined course when compared to congenital and other types of acquired coronary artery fistulas. Asymptomatic patients should be observed and managed medically as they may have spontaneous closure of their fistulas. Percutaneous embolization with either detachable balloons or coils combined with stenting of the ungrafted artery is an effective and safe method of treatment for symptomatic patients.



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