Building a better bypass with emphasis on bilateral internal mammary grafting

markdownabstractAbstract The goals for this thesis are 1) to encourage the use of bilateral internal mammary artery (BIMA) grafting more frequently so that many more patients receive the ‘BIMA benefit’ and 2) to ensure that an increase in bilateral IMA grafting is achieved with accuracy and no greater morbidity than that which is achieved with one IMA and the rest of bypasses with a saphenous vein. Revascularization of diseased coronary arteries may be accomplished in one of two ways: by percutaneous coronary intervention (PCI) or by coronary artery bypass graft surgery (CABG). The principal difference between the two procedures involves the length of coronary artery needed to be addressed to improve blood flow to the heart. PCI with placement of stents must open all significantly obstructed areas along a coronary artery whereas in CABG, a surgeon needs only a ‘postage-stamp’ size of disease-free artery in order to perform an anastomosis. However as with everything in life, there are pros and cons to both approaches. PCI is quicker and requires no surgical incision from which a patient must recover. CABG is a major surgical procedure with all the inherent risks associated with a median sternotomy and the use of a heart-lung machine (or not, in the case of off-pump CABG). Patients are naturally drawn to the less invasive PCI but recent publications, most notably the recent 5 year SYNTAX trial (Ref1) results have clearly shown an advantage for CABG for the majority of patients needing revascularization. ‘Pay me now or pay me later’ is a saying that comes to mind… Coronary artery bypass grafting (CABG) has remained the cornerstone treatment for obstructive coronary artery disease for more than 50 years. Chapters 3 and 4 outline the past and the present/future of the CABG procedure, respectively. Chapters 5 and 6 are commentary articles on the benefit of bilateral IMA grafting. Chapter 7 addresses the possibility of an age cut-off as to the survival benefit of BIMA use. BIMA grafting is technically more challenging – all the more reason to use an intra-operative assessment of graft function to ensure bypasses are functioning to the best of a surgeon’s ability before the patient leaves the operating room. (Chapter 8) Operative revascularization is more invasive compared to that with PCI but cementing a sternum solid within 24 hours of operation may possibly reduce the relative invasiveness of CABG, especially when the revascularization rate for CABG is so much lower than PC I (Chapter 9) BIMA grafting is definitely associated with an increase in deep sternal wound infection, one of the most dreaded complications of CABG surgery and commonest reason for not performing BIMA grafting. However if many preventive measures/procedures are used meticulously and consistently on every patient, the risk for this complication can be reduced to almost zero. (Chapter 10) Complete revascularization has been found to improve the survival of patients undergoing CABG surgery; however it is not always possible to completely revascularize a patient. For example if coronary arteries are very small, diffusely diseased or are mostly in scar tissue it may not be possible or even advisable to perform bypasses to such arteries. We have shown that if total arterial grafting (with the majority of arterial grafts of internal mammary artery origin) is used, there is no difference in midterm survival if a patient is incompletely revascularized by inability to bypass one of three artery systems. This is a valuable point as there is only a finite amount of arterial conduit available and there may not be enough to perform all bypasses desired. (Chapter 11 and 12) BIMA grafting does take increased operative time but harmonic ultrasound technology used to skeletonize IMAs helps shorten this time. (Chapter 13 and 14) Chapter15 discusses sequential bypass grafts and the inherent risk of losing the second anastomosis in preference to the first, a serious problem if the second anastomosis is to the more important artery. Chapter 16 presents a rare complication of CABG surgery but from this problem, an operative technique has been developed that is applicable to similar patients with prohibitively calcified coronary arteries. To summarize: It is the author’s wish to 1) refute every reason used as to why BIMA grafting is not performed more frequently and 2) to establish credible studies and guides to encourage their use.