Vein graft neointimal hyperplasia: Prevention is better than cure

Letters to theEditor

Vein graft neointimal hyperplasia:Prevention is better than cureTo the Editor:We read with interest the article by ThomasSchachner.1 This review was an excellentdescription of the multiple factors involvedin the initiation and progression of neoin-timal hyperplasia in vein grafts during cor-onary bypass surgery. Clearly much hasbeen learned in recent years about the typeand origin of the cells composing the hyper-plastic tissue and other various factors in-volved in the hyperplastic process. Schachnerhas proposed multiple pharmacologic strate-gies to reduce this hyperplastic process.

However, we contend that this approachis similar to closing the stable door after thehorse has bolted. Surely it is better to pre-vent the damage to the vein in the firstplace than to try to reverse the results interms of neointimal hyperplasia after thedamage has been done. There is a wealth ofliterature showing the adverse effects ofsurgical trauma, especially high pressuredistension during vein graft harvesting, onthe subsequent fate to the vein graft.2

However, surgeons know instinctivelythat before they can implant a vein graft itmust have an adequate lumen and be free ofspasm. If vein spasm is present then the sur-geon invariably uses sufficient pressure toremove the spasm. We and others haveshown that this procedure of distending thevein can generate extremely high intralu-minal pressures and lead to widespread lossof endothelial coverage.2,3 We have alsoshown that this loss of endothelium can beprevented by pharmacologic relaxation ofthe vein with appropriate vasodilator agents.4

We have shown in an extensive seriesof organ bath studies and clinical trials thata mixture of glyceryl trinitrate and vera-pamil is a highly effective means of reduc-ing vein graft spasm. This combination retlaxes the saphenous vein by 2 mechanisms.It has a rapid onset of effect and a longduration of action.5 A more commonly usedpharmacologic agent is papaverine. How-ever, we have shown that this agent results ininferior preservation of the endothelium.4

Papaverine also has a number of otherundesirable effects, especially endothelialdamage from the acidity of its solution,particularly if it is undiluted.6 Recent stud-ies have shown other adverse effects ofpapaverine on the endothelium.6 Papaver-ine, however, continues to be used becauseit is readily available in the operating room.

Although pharmacologic inhibition ofvein graft neointimal hyperplasia is possi-ble, it is more important to prevent it in thefirst place by using pharmacologic relaxationof the vein graft conduit during harvesting.

Franklin Rosenfeldt, FRACSa

Guo Wei He, MD, DScb

Nick Roubos, MB, BS, BMedScic

Department of Cardiothoracic Surgerya

Monash University Department of SurgeryAlfred Hospital and the Baker Heart

Research InstituteMelbourne, Australia

Department of Surgeryb

The Chinese University of Hong KongDepartment of Cardiothoracic Surgeryc

Alfred Hospital MelbourneMelbourne, Australia

References

1. Schachner T. Pharmacological inhibition ofvein graft neointimal hyperplasia.J ThoracCardiovasc Surg. 2006;131:1065-72.

2. Ramos JR, Berger K, Mansfield PB, SauvageLR. Histologic fate and endothelial changesof distended and nondistended vein grafts.Ann Surg. 1976;183:205-28.

3. Angelini GD, Passani SL, Breckenridge IM,Newby AC. Nature and pressure dependenceof damage induced by distension of humansaphenous vein coronary artery bypass grafts.Cardiovasc Res. 1987;21:902-7.

4. Roubos N, Rosenfeldt FL, Richards SM,Conyers RA, Davis BB. Improved preserva-tion of saphenous vein grafts by the use ofglyceryl trinitrate-verapamil solution duringharvesting. Circulation. 1995;92(9 Suppl):II31-6.

5. He GW, Rosenfeldt FL, Angus JA. Pharma-cological relaxation of the saphenous veinduring harvesting for coronary artery bypassgrafting. Ann Thorac Surg. 1993;55:1210-7.

6. Rubens FD, Labow RS, Meek E, Bedard E,Gill IS, Dudani AK, et al. Papaverine solu-tions cause loss of viability of endothelial cells.J Cardiovasc Surg (Torino). 1998;39:193-9.

doi:10.1016/j.jtcvs.2006.09.082

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1118 The Journal of Thoracic and Cardiovascular Surgery ● April 2007