Invited Commentary

Abstract

Spasm of small arterial grafts is a real problem in coronary artery bypass surgery. Intraoperatively, good surgical techniques such as skeletonization during harvesting and minimal graft handling can minimize the incidence of this challenging complication. Although papaverine used topically as well as by intraarterial injection can reverse the spasm and improve blood flow through a conduit, postoperative spasm of the internal thoracic artery or other arterial conduits such as gastroepiploic or radial arteries can be very difficult to diagnose as well as treat. Luckily, with excellent surgical techniques, this complication is not very prevalent. Many agents, such as verapamil, nitroglycerin, amlodipine have been recommended in this situation, based more on common sense rather than hard science. In this issue of The Annals, Gao and colleagues [1Gao G. Liu X.-C. Jing W.-B. Yang Q. He G.-W. Vasorelaxation induced by new third-generation dihydropyridine calcium antagonist azelnidipine in human internal mammary artery.Ann Thorac Surg. 2013; 96: 1316-1321Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar] present in vitro experiments investigating the effect of the long-acting, third-generation calcium-channel antagonist azelnidipine on human internal thoracic artery conduits harvested at the time of surgery. This drug is reportedly available in Japan as an antihypertensive agent but is not yet available in the United States. In their current publication, the authors demonstrate a vasodilatory effect of azelnidipine, which is similar to the second-generation calcium antagonist amlodipine. However, the benefit of this drug may lie in that it is lipid soluble and has a strong affinity to vascular tissues. Hence, it may have a more prolonged effect than amlodipine or other vasodilator agents. Pretreatment with this drug at concentrations at its currently approved antihypertensive dose prevented subsequent vasoconstriction by KCl and a thromboxane agonist. It would have been more clinically relevant if a drug such as norepinephrine, which is more commonly used in the management of post-coronary artery bypass graft surgery patients, had been tested in the experiments rather than KCl and a thromboxane agonist. In any case, a clinical trial is needed to confirm these in vitro findings. Because spasm in the surgical setting is very difficult to investigate given its rarity and the difficulty in diagnosis, the trial will have to be conducted by interventional cardiologists. They encounter arterial spasms more often, both in native coronary arteries as well as in bypass grafts. A properly designed and executed clinical trial will be greatly appreciated by both surgeons and cardiologists. Vasorelaxation Induced by New Third-Generation Dihydropyridine Calcium Antagonist Azelnidipine in Human Internal Mammary ArteryThe Annals of Thoracic SurgeryVol. 96Issue 4PreviewGraft spasm remains challenging in coronary artery bypass graft (CABG) surgery. Calcium antagonists are commonly used in patients with coronary artery disease. We investigated the inhibitory effect of the new third-generation dihydropyridine calcium antagonist azelnidipine on the vasoconstriction in human internal mammary artery (IMA) from patients undergoing CABG. Full-Text PDF