Saphenous Vein Graft-to-Pulmonary Artery Fistula Presenting With Coronary Ischemia and Right Ventricular Dysfunction

Abstract

Background

Acquired coronary and coronary-cameral fistulas are rare after coronary artery bypass grafting (CABG), and saphenous vein graft fistulas are exceptionally uncommon, especially without graft aneurysm.

Case Summary

A 61-year-old man with previous CABG presented with typical chest pain, elevated high-sensitivity troponin, and a continuous murmur. Echocardiography showed impaired right ventricular function. Coronary angiography revealed patent grafts, distal graft stenosis, and a sequential saphenous vein graft-to-left pulmonary artery fistula, confirmed by coronary computed tomography without graft aneurysm. The patient declined invasive treatment and remained asymptomatic on maximal medical therapy at 6 months.

Discussion

Most post-CABG fistulas to the pulmonary vasculature arise from the left internal mammary artery and may cause coronary steal syndrome. Saphenous vein graft fistulas are much rarer and are usually associated with graft aneurysm. This case is unique because the fistula occurred without aneurysmal degeneration.

Take-Home Message

A saphenous vein graft–to–pulmonary artery fistula is a rare post-CABG complication presenting with angina, continuous murmur, or right ventricular dysfunction, requiring multimodal diagnosis and individualized treatment.

Visual Summary

Acquired coronary artery and coronary-cameral fistulas are uncommon vascular abnormalities that may develop after coronary artery bypass grafting (CABG), trauma, infection, neoplasm, or invasive cardiovascular procedures.1, 2, 3 Although some fistulas remain clinically silent, hemodynamically relevant communications may result in coronary steal syndrome, myocardial ischemia, arrhythmias, volume overload, pulmonary hypertension, or heart failure.3, 4, 5 In patients with previous CABG, fistulous communications involving the pulmonary vasculature have been described most frequently between the left internal mammary artery (LIMA) and the pulmonary artery or pulmonary vascular bed.4, 5, 6, 7 By contrast, saphenous vein graft-to-pulmonary artery fistulas are exceptionally rare. When saphenous vein graft fistulas are reported, they are often associated with aneurysmal degeneration of the venous graft, and they may communicate with the pulmonary artery or other cardiovascular structures.7, 8, 9

We present a rare case of a sequential saphenous vein graft–to–left pulmonary artery fistula without associated graft aneurysm, presenting with exertional angina, coronary ischemia, and right ventricular systolic dysfunction. The diagnosis was established by coronary angiography and confirmed by coronary computed tomography.

History of Presentation

A 61-year-old man was admitted to our emergency department with exertional chest pain that had progressively developed over the preceding 3 months.

Past Medical History

The patient had undergone CABG 5 years earlier at another institution. His medical history was also significant for hypertension and hyperlipidemia. The patient was receiving regular medical therapy for cardiovascular risk factors.

Differential Diagnosis

Based on the clinical presentation and cardiovascular risk factors, the differential diagnosis included acute coronary syndrome, chronic coronary syndrome, and acute pulmonary embolism.

Investigations

On admission, the patient was hemodynamically stable. Physical examination was unremarkable except for a continuous murmur, most prominent along the left sternal border. There were no signs of peripheral edema, jugular venous distension, or pulmonary congestion. Electrocardiography showed sinus rhythm with nonspecific T-wave changes in lead DIII. Laboratory testing revealed a D-dimer level <500 ng/mL and a moderately elevated high-sensitivity cardiac troponin level of 61 ng/L. Transthoracic echocardiography demonstrated preserved left ventricular systolic function, with a left ventricular ejection fraction of 55% and mild mitral regurgitation. However, right ventricular systolic function was impaired. Tricuspid annular plane systolic excursion was 13 mm, and tricuspid annular systolic velocity was 7 cm/s. Right ventricular systolic pressure was 29 mm Hg, and the inferior vena cava measured 12 mm with good respiratory variation. No other definite echocardiographic cause of right ventricular dysfunction was identified.

Coronary angiography demonstrated severe native coronary artery disease, including 70% stenosis of the left main coronary artery, proximal total occlusion of the left anterior descending artery (LAD), obtuse marginal artery, and right coronary artery (RCA), and 80% proximal stenosis of the circumflex artery. The LIMA-to-LAD and the aorto-circumflex saphenous vein graft were patent. The sequential saphenous vein graft to the RCA and septal branch of the LAD was patent along the RCA course. However, critical stenosis was detected distal to the septal branch anastomosis. In addition, angiography revealed a fistulous communication originating from the sequential saphenous vein graft and draining into the left pulmonary artery (Figure 1, Video 1).

Figure 1.

Coronary Angiography View of the Aorto-RCA and Aorto-LAD Septal Sequential Saphenous Graft Fistula to the Left Pulmonary Artery (Arrow)

LAD = left anterior descending artery; RCA = right coronary artery.

Because echocardiography showed no evidence of overt pulmonary hypertension, right heart catheterization was not performed. Coronary computed tomography was performed to confirm the diagnosis and better define the anatomical course of the fistula. Three-dimensional coronary computed tomography clearly demonstrated a fistulous tract between the saphenous vein graft and the left pulmonary artery, without evidence of saphenous vein graft aneurysm formation (Figures 2 and 3). According to the available report of the preoperative angiography performed before CABG, there had been no congenital or acquired coronary-cameral fistula. However, the original angiographic images could not be obtained because the procedure had been performed at another institution.

Figure 2.

Three-Dimensional Volume-Rendered CT Image Demonstrating the Saphenous Venous Graft to the Left Pulmonary Artery

The arrow denotes the fistula. CT = computed tomography; PA = pulmonary artery.

Figure 3.

Axial Maximum-Intensity Projection CT Image Demonstrating Saphenous Venous Graft to Left Pulmonary Artery

CT = computed tomography; PA = pulmonary artery.

Management

The patient was discussed by the multidisciplinary heart team. Given his symptoms, severe native coronary artery disease, graft anatomy, suspected coronary steal phenomenon, and right ventricular dysfunction, redo surgery was recommended. Percutaneous closure with coil embolization was also considered as an alternative treatment option. However, the patient declined redo surgery and all invasive procedures, including coil embolization. Therefore, he was discharged on optimized medical therapy, including dual antiplatelet therapy for troponin-positive acute coronary syndrome, in accordance with contemporary American College of Cardiology/American Heart Association guideline recommendations,¹⁰ together with a calcium-channel blocker, high-dose nitrate therapy, and ranolazine.

Outcome and Follow-Up

One month after discharge, myocardial perfusion scintigraphy demonstrated an ischemic burden of <5% in the RCA territory. At the 6-month follow-up, the patient remained asymptomatic under medical therapy, without recurrent hospitalization or progression of symptoms.

Discussion

Coronary artery and coronary-cameral fistulas may be congenital or acquired. Acquired fistulas are uncommon and have been reported after CABG, trauma, infection, neoplasm, and invasive cardiovascular procedures.^1,3 In the post-CABG setting, fistulous communications may involve arterial or venous bypass grafts and may drain into cardiac chambers, coronary veins, pulmonary arteries, or pulmonary vascular structures.4, 5, 6^,8,9

Most post-CABG fistulas involving the pulmonary vasculature arise from the LIMA. LIMA-to–pulmonary artery fistula is a rare but well-recognized cause of recurrent angina after CABG and may lead to coronary steal syndrome when blood flow is diverted from the coronary circulation into the low-resistance pulmonary vascular bed.^4,5 Guler et al⁷ also reported a case series of fistulous communications between the internal mammary artery and pulmonary vasculature, supporting the importance of this entity in patients with previous CABG and recurrent symptoms.

Saphenous vein graft fistulas are considerably rarer. Available reports suggest that saphenous vein graft fistulization is frequently associated with aneurysmal degeneration of the venous graft.7, 8, 9 Aiba et al⁵ reported a large saphenous vein graft aneurysm with fistulous communication and reviewed similar cases. Dabboussi et al⁸ described a fistula between a saphenous vein graft aneurysm and the pulmonary artery trunk. Lasic et al⁹ reported a saphenous vein graft aneurysm fistula causing pulmonary artery dissection. In contrast, the present case demonstrated a direct fistulous communication from a sequential saphenous vein graft to the pulmonary artery without venous graft aneurysm, making it particularly unusual.

The pathophysiological mechanism of bypass graft–to–pulmonary artery fistula formation is not fully understood. Several mechanisms have been proposed, mainly based on LIMA-related fistulas. These include recanalization of divided graft side branches, especially when side branches are managed by electrocautery rather than ligation; inadvertent surgical injury or disruption of adjacent pulmonary vascular structures; direct contact between the bypass graft and pulmonary vessels; and postoperative inflammation with angiogenesis through small interconnecting vessels.4, 5, 6 The clinical presentation depends on fistula size, drainage site, shunt volume, graft territory, presence of native coronary artery disease, and associated aneurysm formation. Small fistulas may remain asymptomatic, whereas larger or hemodynamically significant fistulas may cause coronary steal syndrome, exertional angina, myocardial ischemia, acute coronary syndrome, arrhythmias, pulmonary hypertension, right-sided volume overload, or heart failure.^4,5,7, 8, 9 In our patient, the combination of exertional chest pain, elevated high-sensitivity troponin, severe native coronary artery disease, graft stenosis distal to the septal anastomosis, and right ventricular systolic dysfunction suggests a complex pathophysiological interaction. The fistulous tract may have contributed to coronary steal, while chronic abnormal drainage into the pulmonary artery may have played a role in right ventricular impairment. No other clear cause of right ventricular dysfunction was identified.

Multimodal imaging is essential in these cases. Coronary angiography remains the key diagnostic modality for identifying graft patency, native coronary lesions, stenotic segments, and abnormal contrast drainage. However, angiography may not fully characterize the 3-dimensional course of the fistula or its relationship with adjacent structures. Coronary computed tomography provides complementary information by delineating the origin, course, drainage site, and possible aneurysmal changes of the graft.⁸

There is no standardized treatment strategy for bypass graft–to–pulmonary artery fistulas because of their rarity and anatomical variability. Conservative medical therapy may be reasonable in patients without symptoms. In contrast, invasive closure should be considered in patients with refractory angina, significant ischemia, relevant shunt, heart failure, arrhythmias, progressive enlargement, or aneurysmal degeneration.^4,5,7, 8, 9 Surgical ligation or redo surgery has traditionally been used, especially in anatomically complex cases or in the presence of graft aneurysm.⁸ However, redo cardiac surgery carries increased operative risk. Transcatheter coil embolization has emerged as an alternative in selected patients and has been successfully used for LIMA-to–pulmonary artery fistulas.⁵

In our patient, both redo surgery and percutaneous closure were considered. The heart team recommended redo surgery because of the patient's graft anatomy, symptoms, suspected coronary steal, and right ventricular dysfunction. However, the patient declined all invasive approaches. Interestingly, myocardial perfusion scintigraphy performed 1 month later demonstrated an ischemic burden of <5% in the RCA territory, and the patient remained asymptomatic at the 6-month follow-up under maximal medical therapy. This outcome does not eliminate the potential clinical significance of the fistula but supports the feasibility of individualized conservative management in carefully selected or treatment-declining patients.

Conclusions

To the best of our knowledge, this is one of the very few reported cases of saphenous vein graft–to–pulmonary artery fistula without associated venous graft aneurysm. The case is clinically important because it demonstrates that a nonaneurysmal saphenous vein graft may form a fistulous communication with the pulmonary artery and may be associated with both coronary ischemia and right ventricular dysfunction.

Take-Home Messages

• •Saphenous vein graft-to-pulmonary artery fistula is an exceptionally rare but clinically relevant post-CABG complication that should be considered in patients with recurrent angina, continuous murmur, unexplained ischemia, or right ventricular dysfunction.
• •Multimodal imaging with coronary angiography and coronary computed tomography is essential for diagnosis, while treatment should be individualized according to symptoms, ischemic burden, anatomy, and patient preference.

Visual Summary.

Clinical Course of a Patient With a Saphenous Vein Graft–to–Pulmonary Artery Fistula Causing Coronary Ischemia and Right Ventricular Dysfunction After Coronary Artery Bypass Grafting

PA = pulmonary artery; RCA = right coronary artery.

Data Availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Declaration of Generative AI and AI-Assisted Technologies

During the preparation of this work, the author used ChatGPT in order to improve language. After using this tool, the author reviewed and edited the content as needed and takes full responsibility for the content of the publication.

Funding Support and Author Disclosures

Dr Oezalp has received congress and travel sponsor support from EHRA outside the submitted work.

Appendix

Video 1

Coronary Angiography View of Aorto-RCA and Aorto-LAD Septal Sequential Sapheous Graft Fistula to Left Pulmonary Artery