Invited Commentary

Hemodynamic Effects of Left Upper Extremity Arteriovenous Fistula on Ipsilateral Internal Mammary Coronary Artery Bypass Graft

Does hemodialysis (HD) affect left internal thoracic artery (LIMA) to coronary artery bypass flow?

According to a previous article,[1] this can be answered by an explicit “Maybe.”

So is it worth being published at all? Is there even a message? We are accustomed to our scientific literature having a clear statement such as: “If you do this, you will have significantly more/less of that.” But obviously this does not hold true for the underlying problem of steal of LIMA to coronary artery bypass because of an ipsilateral upper extremity HD shunt during HD.

One may say that the study does not suffice, especially that the number of patients is too small. But then, how many patients have this problem and what is already known?

During the past 3 years the percentage of patients who had undergone isolated coronary artery bypass graft (CABG) on HD in Germany was 1.5 to 1.6%, equaling to more than 600 patients each year. This means that in 3 years the average (German) cardiac surgery department will see an estimated 20 patients who have undergone isolated CABG (assumed LIMA use of 90%) on HD (with shunts in varying locations). Principally, there are many patients potentially affected by steal phenomenon, but only very few are seen in each center. This is reflected by the current literature.

Kato in 1993 presumably was the first to report one patient with (pre-CABG!) angiographically detected diastolic LIMA steal because of an ipsilateral arteriovenous fistula and recommended preoperative angiography of LIMA in dialysis patients.[2] Later, Gaudino et al found “hemodynamically evident flow steal and consequent myocardial ischemia during hemodialysis in patients with upper extremity arteriovenous fistula and ipsilateral internal thoracic artery to coronary graft,” with “major implications for patients' management, both for nephrologists and cardiac surgeons.”[3] Their data were based on only five patients! Kinoshita et al also examined five patients on postoperative HD and found “flow reduction of the ITA graft ipsilateral to an upper-extremity arteriovenous fistula during postoperative hemodialysis, even when the skeletonization technique was used.”[4] On the contrary, Rahbar et al stated that “changes in arteriovenous fistula flow state did not significantly alter Doppler flow hemodynamics of either the ipsilateral or contralateral in-situ internal thoracic artery” in a study on 15 patients.[5] Cluzel et al reported a patient after CABG including LIMA–LAD artery graft and ipsilateral arteriovenous fistula who presented with cerebral and hemodynamic symptoms during dialysis, but the cause was a significant stenosis of the proximal subclavian artery with retrograde flow in internal mammary artery graft and vertebral artery.[6] All symptoms resumed after a radiological intervention.

So in conclusion, very limited and inconsistent information is available, and further unexpected secondary diagnoses may be responsible for problems.

Concerning the excellent long-term performance of internal mammary artery coronary bypass, should it be withheld in one of the sickest patient groups with vascular problems, namely those on HD, because of a “maybe” interference? Or should we recommend a “free-graft,” as long as a potential harm must be feared?

We just don't know! Therefore the preceding article is of interest, because it addresses an important issue; even if there is no real message it should encourage further research in this field.

To conclude: As far as I am aware, the present study comprises the largest number of patients investigated for the underlying issue. The authors found no statistical difference in LIMA-bypass flow pre- and during HD, but they did so in individual patients (according to ECG and echocardiographic findings). Identifying this subgroup may be vitally important. Thus, a larger or even multicenter trial is definitely necessary.

• References

• 1 Coskun I, Colkesen Y, Altay H , et al. Hemodynamic effects of left upper extremity arteriovenous fistula on ipsilateral internal mammary coronary artery bypass graft. Thorac Cardiovasc Surg 2012; 61 (8) 663-668
• 2 Kato H, Ikawa S, Hayashi A, Yokoyama K. Internal mammary artery steal in a dialysis patient. Ann Thorac Surg 2003; 75 (1) 270-271
• 3 Gaudino M, Serricchio M, Luciani N , et al. Risks of using internal thoracic artery grafts in patients in chronic hemodialysis via upper extremity arteriovenous fistula. Circulation 2003; 107 (21) 2653-2655
• 4 Kinoshita T, Asai T, Ishigaki T. Steal from skeletonized internal thoracic artery graft during hemodialysis after coronary artery bypass grafting. Heart Surg Forum 2010; 13 (4) E254-E256
• 5 Rahbar R, McGee WR, Birdas TJ, Muluk S, Magovern J, Maher T. Upper extremity arteriovenous fistulas induce modest hemodynamic effect on the in situ internal thoracic artery. Ann Thorac Surg 2006; 81 (1) 145-147
• 6 Cluzel P, Chabrot P, Citron B , et al. [Aortocoronary bypass, haemodialysis and internal mammary artery steal]. Nephrol Ther 2009; 5 (7) 648-651