Editorials

Arterial bypass surgery and smokers

BMJ 1994; 308 doi: https://doi.org/10.1136/bmj.308.6929.607 (Published 05 March 1994) Cite this as: BMJ 1994;308:607
  1. J T Powell,
  2. R M Greenhalgh

    Whether smokers should be offered bypass surgery remains controversial despite the extensive airing the topic had in the BMJ's columns last year.1 Nearly all patients requiring such operations have smoked for long periods.2 Are there any benefits of giving up at this late stage?

    With non-invasive techniques and objective markers of smoking it has been shown that one year after peripheral arterial bypass surgery the patency of femoropopliteal vein grafts in continuing smokers (63%) is significantly less than the patency of grafts in those who no longer smoke (84%).3 The results of prosthetic distal bypass surgery are similar - the chance of graft failure is doubled in smokers.4 Surveillance of the patency of coronary artery bypass grafts is more difficult, requiring serial angiography, and no study that has used objective markers of smoking has been reported. Nevertheless, some studies have reported an association between smoking and an increased risk of failed coronary bypass grafts.5,6 Continuing to smoke after surgery also has an adverse influence on the prognosis of aortofemoral bypass grafts.7

    On the basis of this evidence what advice should we give? Undoubtedly, patients with angina or intermittent claudication who smoke should be advised not to smoke and informed that their problem is most likely related to smoking. Switching to a cigarette with a lower yield of tar or nicotine is not sufficient.8 People who switch from cigarette to pipe or cigar continue to inhale, and those who reduce the number of cigarettes they smoke are likely to compensate by smoking more efficiently or switching to a brand with a higher yield of nicotine.9 Although patients must stop smoking, this may not be easy. In a series of 550 current smokers presenting with leg ischaemia to the regional vascular service at Charing Cross Hospital, London, 140 (25%), including 53 (30%) of those undergoing immediate surgery, were persuaded to stop smoking. This success in dissuading patients from smoking is comparable to rates of stopping after myocardial infarction or lung resection for cancer and is considerably higher than that obtained with nicotine patches in general practice.10,11 Sometimes the patient needs a nasty shock before heeding advice to stop smoking.

    Our understanding of the toxic effects of smoking on the vasculature is improving. Smoking damages the endothelium and potentiates arterial thrombosis. One early manifestation of endothelial damage is the loss of endothelium dependent relaxation, which occurs in the arteries and veins of smokers.12,13 This evidence of damage lasts for several weeks after a person stops smoking; normal endothelial function in the bypass conduit would improve the chances of graft patency. Stopping smoking is also associated with a fall in both the plasma fibrinogen concentration and the associated risk of ischaemic heart disease.14 Moreover, increased plasma fibrinogen concentration is a potent risk factor for a femoropopliteal bypass graft becoming occluded.3,4 The proliferation of smooth muscle cells, causing intimal hyperplasia, is another mechanism contributing to the failure of bypass grafts. Proliferation of smooth muscle cells also causes restenosis after carotid endarterectomy, and smoking exacerbates this.15 In addition, the progressive fall in lung function that accompanies smoking is halted by stopping smoking, and this is likely to have a substantial impact on the outcome of general anaesthesia.16

    Smokers' ability to deceive their doctors about their continued smoking may still go unrecognised.17 Ill smokers may prefer to bask in the apparent virtue of being reformed smokers rather than be told yet again to stop smoking before help is offered. Objective markers of smoking such as blood carboxyhaemoglobin concentrations or plasma or urinary cotinine concentrations can show the truth and clarify the association between smoking and the outcome of vascular reconstruction.2 For example, about one quarter of patients undergoing femoropopliteal vein bypass surgery are covert smokers.2 In the context of the current controversy concerning eligibility for bypass surgery it is likely that deception among smokers will increase, making a policy of not operating on smokers ridiculous if the surgeon does not know which patients are telling the truth.

    For patients at risk of death, stroke, or loss of a limb surgery must be offered at once, without waiting for the patient to stop smoking. Antismoking advice should be given during convalescence. In the category of patients with inconvenient arterial disease which is not life or limb threatening but in whom surgery could improve the quality of life (for example, patients with intermittent claudication and some forms of angina) it is reasonable to enter a contract offering surgery if the patient stops smoking. The advantages of stopping smoking must be explained clearly and patients should be offered counselling to help them stop. After two to three months some ex-smokers' symptoms will have improved and bypass surgery will no longer be required. For other patients who have stopped smoking (confirmed by objective tests) but not improved, surgery can be offered. This principle will lead to lower operative morbidity, fewer postoperative pulmonary complications, and better chances of long term graft patency.3,4,7,16,18 Patients who continue to smoke but in whom the arterial disease is not yet critical should be reminded that the operative risk and chance of bypass failure remain too high to justify surgery. Nevertheless, if the disease progresses no smoker should be denied urgent surgery to prevent amputation, stroke, or death.

    References

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