Coronary Steal From a Left Internal Mammary Artery Bypass Graft via High Output Hemodialysis Arteriovenous Fistula

 

A 73-year-old African-American female with past medical history of coronary artery disease (CAD) status post three-vessel coronary artery bypass grafting (CABG), diabetes, hypertension, hyperlipidemia, end stage renal disease (ESRD) on hemodialysis (HD) via left upper arm arteriovenous fistula (AVF), and recently treated left subclavian artery stenosis with a stent presented with angina during HD. Stress test revealed a reversible defect in the mid anterior wall consistent with ischemia. Prior to definitive management, subsequent dialysis session was prematurely stopped due to complaints of nausea and dyspnea. Soon after, the patient became altered, hypotensive, and bradycardic, requiring intubation, saline bolus, and atropine. At this point, the decision was made to perform coronary angiography to determine the source of myocardial ischemia.  

 

Angiography revealed a patent left subclavian artery stent and patent left internal mammary artery (LIMA) bypass graft supplying the left anterior descending (LAD) artery. However, angiography of the subclavian artery beyond the stent (Figure 1A) revealed significantly high and brisk flow through the AVF and rapid filling of the left subclavian vein (Figure 1B), superior vena cava, and right atrium. This was suggestive of coronary steal from LIMA via AVF resulting in angina during HD.

 

Stenting of the native LAD was decided to be the most appropriate management in this patient, potentially excluding LIMA steal. Of note, the patient has remained asymptomatic during subsequent dialysis sessions performed following the intervention.

 

 

In patients with ESRD on HD via left upper extremity AVF and prior LIMA bypass graft, coronary steal presents a rare but challenging condition to treat between persistent angina and salvage of AVF versus LIMA. In the ESRD population, there is known acceleration of atherosclerosis due to factors such as anemia, elevated lipoprotein and homocysteine, microinflammation, and elevated thrombogenic factors.¹ The preferred access for HD in ESRD is a mature AVF in the arm. The combination of increased risk of stenosis and a high flow AVF in the ipsilateral extremity renders these patients susceptible to coronary steal.

 

A pressure gradient between donor and recipient arteries represents a physiologic steal. Coronary subclavian steal syndrome (CSSS) occurs when there is reversal of flow from a bypassed coronary artery (commonly the LAD) into the subclavian artery via the corresponding bypass graft (usually a LIMA). The incidence of CSSS in patients with coronary artery disease ranges from 0.1 to 3.4%.²  

 

CSSS can be acquired due to brachiocephalic AVF with reversal of LIMA flow from the low vascular resistance within the fistula. It is well known that placement of AVF can cause increased cardiac output and increased cardiac oxygen demand.³ This is because the left AVF is a low-resistance zone that draws flow away from a higher resistance zone, such as a LIMA to LAD bypass graft. It is important to note that resistance of the left AVF becomes even lower during dialysis, as blood is being withdrawn from the fistula.⁴ When this reversal of flow within the LIMA occurs, the patients are known to experience angina and CSSS.

 

Treatment of CSSS involves termination of the relationship between coronary ischemia and the upper extremity. Options include revascularization of native coronary artery to avert dependence on the bypass graft from the corresponding upper extremity or switching the AVF to the contralateral arm. Alternative options would be to repeat coronary artery bypass graft surgery with a different graft or create AVF in the lower extremity. 

 

This case demonstrates that coronary steal from a LIMA by an ipsilateral upper extremity AVF can precipitate ischemia after bypass grafting in a patient with ESRD on HD. Hence, CSSS should be taken into consideration when placing AVF in patients with prior LIMA graft or utilizing LIMA graft in patients with prior left upper extremity AVF. Currently, the treatment of choice is endovascular stenting at available centers due to the fewer complications associated with this minimally invasive procedure.⁵