Coronary reoperations are among the most challenging problems adult cardiac surgeons ever face. When compared with patients undergoing primary surgery, candidates for reoperation are older, have more comorbidities and worse cardiac function. They present substantial and sometimes unique technical challenges including sternal reentry, patent but atherosclerotic vein grafts, patent arterial grafts, severe noncardiac atherosclerosis, lack of bypass conduits, and very diffuse and severe coronary artery disease.

In addition, coronary reoperations are becoming less common. Their decrease in frequency appears to have multiple causes including a decrease in vein graft atherosclerosis (probably due to improved control of atherosclerotic risk factors), increased use of ITA grafts, decreasing numbers of primary coronary bypass operations, percutaneous treatments for coronary artery disease, and an increased understanding of the indications for reoperation. The STS database recorded 8,995 reoperations countrywide in 2005 and 7,297 during 2013. This trend means that when reoperation is needed, surgeon experience with these problems may not be extensive.

The principles of achieving a successful coronary operation are:

The principles of preoperative and intraoperative management are directed toward achieving those goals.

The first step in a coronary reoperation is defining a good reason to do it. Those reasons fall into three categories. First, the patient is in a life-threatening situation as defined by coronary anatomy, cardiac function, and cardiac physiology. Second, the patient has truly severe angina that is life-limiting and that is not treatable with medication or intervention, and is caused by an anatomic situation that can be improved by bypass surgery. Third, rarely, there is a patient who is not highly symptomatic but logic seems to dictate that over a period of time they will be better-off with repeat surgery based on the possibility of progression of stenoses in critical grafts or coronary vessels.

Patient prognosis is best predicted by a combination of coronary anatomy, myocardial function, myocardial ischemia, and the projected longevity of coronary lesions and bypass grafts supplying viable myocardium. Much is known about the statistical prognosis of patients with no prior surgery or no patent bypass grafts but less is known about patients for whom functioning (but perhaps stenotic) bypass grafts constitute part of their myocardial blood supply. During the 1980s we performed extensive follow-up studies of patients who had had previous bypass surgery and came to the conclusions that (1) if a patient had a stenotic and atherosclerotic saphenous vein bypass graft to the anterior descending coronary artery, their prognosis was significantly impaired and reoperation improved that prognosis; and (2) if the patient had a patent internal thoracic artery graft to the anterior descending coronary artery, reoperation could not be demonstrated to improve their prognosis. These two principles have been, in general, borne out with subsequent follow-up studies and are a good place to start in terms of defining the logic of whether or not reoperation is in the patient’s interest. However, many patients fall into neither of these anatomic situations, and the impact of surgery on prognosis may be a matter of judgment.

Thus, the first step in evaluation is an accurate and complete coronary angiogram. This is not as easy as it sounds and it is an advantage to have a copy of the previous operative note for the cardiologist to use as a guide. Most commonly missed at angiography are previously constructed vein bypass grafts or arterial grafts and a road map of the previous operation is very helpful in the performance and interpretation of the repeat angiogram. Functioning myocardium always has an identifiable blood supply and failure to define a coronary vessel supplying blood to a contracting myocardial segment usually is caused by a failure to inject a graft or coronary artery. During coronary angiography both internal mammary arteries should be injected to see if they are available to use as graft during reoperation in addition to making certain that they were not used in the previous operation.

In addition to the knowledge of coronary anatomy, the overall myocardial function is important to assess. Also important is a functional test that documents whether or not myocardial ischemia exists either at rest or with exercise. In general, echocardiography, often including stress echocardiography, is used for this purpose. Echocardiography can define the overall resting right and left ventricular function, specific wall motion abnormalities that may or may not fit with anatomic coronary or bypass lesions, the location of those abnormalities, and the response to stress. Nuclear testing including PET and thallium can be used for similar purposes.

It is also wise to define the other bypass conduits that may be available for grafting and their quality prior to operation. Venous Doppler and radial artery perfusion studies should be carried out for all patients for whom reoperation is contemplated. Failure to identify bypass conduits that can be used to accomplish the goals of revascularization may represent a contraindication to reoperation. In the balance between the risk and benefit of repeat surgery, the conduits that are available and their potential longevity should be carefully considered. The interoperative discovery that there are no bypass conduits available to use for revascularization is not a good thing. Thus, coronary angiography, myocardial functional testing, and conduit evaluation should define the indications and opportunity for surgery as well as the level of improvement that can be expected with reoperation.

Many comorbid conditions can impact the risk of reoperation and should be assessed. Diffuse atherosclerosis is not easy to quantify but as CT scanning is carried out for all reoperative candidates, ascending aorta atherosclerosis can usually be identified. Noninvasive carotid studies should be carried out in the face of known peripheral vascular disease or neurologic symptoms. Pulmonary function tests can quantify the level of pulmonary disability and renal abnormalities impact both the overall risk of surgery and the risk of postoperative renal function requiring dialysis. Bleeding and clotting disorders including a history of heparin-induced thrombocytopenia may impact reoperations and can be identified prior to operation.