Cardiology

Revascularization

General description of procedure, equipment, technique

Since the first documented successful case of the aortocoronary bypass grafting by Dr. V. Kolesov in Leningrad in 1964, coronary artery bypass grafting (CABG) has prolonged lives and improved quality of life of countless patients worldwide.  The primary objective of CABG is to provide unobstructed blood flow to the areas of myocardium that are ischemic, or at risk of developing ischemia.

As such, it is employed widely for the treatment of coronary artery disease (CAD) and its complications.  The operation is most commonly performed through the median sternotomy approach with the help of cardiopulmonary bypass on arrested heart. 

Reversed saphenous vein grafts, internal thoracic artery grafts, and other arterial conduits are grafted on the target major epicardial vessels to provide flow to the portions of these vessels positioned downstream from the hemodynamically significant stenoses. 

Proximal anastomoses of vein and free arterial grafts are positioned most commonly on the ascending aorta.  Pedicled internal thoracic grafts and inferior epigastric artery grafts use their respected normal anatomic  inflow to provide blood flow to the proximally obstructed targets.

Another surgical modality for the treatment of CAD is transmyocardial revascularization.  Laser energy source is used to create multiple channels through the left ventricular myocardium to improve direct perfusion to the myocardium in the areas of the heart that cannot be revascularized by coronary bypasses or with percutaneous intervention. 

In addition creation of the channels is thought to promote angiogenesis in the myocardium and to provide partial denervation of the heart which in theory could decrease anginal symptoms.  Recent advances in technology allow the procedure to be performed on the beating heart.

Indications and patient selection

Broadly speaking, CABG is indicated for the treatment of the CAD and its complications.  It is also, albeit much less commonly, performed for correction of various congenital coronary anomalies.

Lastly, CABG is performed occasionally for the treatment of trauma to major coronary arteries and for the treatment of Kawasaki disease.  The goal of CABG is to provide relief of anginal symptoms, prolong survival of the patients with CAD, prevent myocardial infarction, and delay, or prevent onset of the congestive heart failure and associated symptoms due to poor left ventricular function. 

CABG is indicated for the patients with chronic stable angina (CSA) with significant left main coronary lesions, left main disease equivalent (proximal LAD lesion and circumflex artery lesion), and three vessel disease.  CSA patients with the two vessel CAD and an appreciable area of myocardium at risk are also candidates for CABG.

The recently published EXCEL Trial examined patients with obstructive left main coronary artery disease and compared CABG and PCI with DES with a fluoropolymer-based cobalt-chromium everolimus-eluting stents in patients with CAD and low or intermediate SYNTAX scores and demonstrated that PCI was noninferior to CABG with respect to the rate of composite end point of death, stroke or myocardial infarction at 3 years. In addition, the NOBLE trial also examined the best treatment strategy for unprotected left main coronary artery disease and concluded that death, myocardial infarction, stroke or repeat revascularizations were significantly lower in CABG arm compared to PCI at 5 years of follow up.

One vessel CAD is most commonly treated with percutaneous coronary intervention (PCI), or medically.  Patients with unstable angina/non-ST segment elevation myocardial infarction (STEMI) should ideally be revascularized during the same admission.

Generally, we recommend selection approach similar to the cases of CSA with the following modifications: patients with ongoing symptoms of hemodynamic compromise, or ongoing angina despite maximal medical therapy and those patients in whom PCI, or thrombolysis failed should be operated on an urgent/emergent basis.

Patients with ST-elevation myocardial infarction can and should be operated on with essentially the same anatomic characteristics of the lesions as the ones used in the cases of CSA.  Emergency CABG should only be considered for the cases when revascularization can be completed within 6 hours of onset of symptoms with the large territory at risk. 

It also should be strongly considered for the cases of STEMI with  mechanical complications, such as free left ventricular wall rupture, postinfarction ventricular septal defect, and papillary muscle rupture.  These conditions are associated with grave prognosis when treated with medical therapy alone.

In the majority of the cases, it is prudent to postpone the surgery in the patients with STEMI for 7 or more days, if possible, to decrease the mortality risk associated with the emergent surgeries for STEMI.

Patients with complications of PCI—such as a retained foreign body in the crucial anatomic location within the coronary circulation and with coronary perforations with impending tamponade as well as the patients with the threatened occlusions with significant myocardial territory at risk—are candidates for surgical revascularization on the emergent basis.

Patients with the valvular heart disease represent a large subset of the patients undergoing cardiac surgery.  Most of these patients (with the exception of <40-year-old males and premenopausal women with no risk factors for CAD) should undergo preoperative cardiac angiography.

In patients with valvular heart disease and CAD concomitant CABG is indicated when there is a >70% stenosis in the coronary artery and acceptable distal target is present.  It should be considered in the patients with 50% to 70% stenosis in the coronary arteries and good distal targets supplying large myocardial areas at risk.

PCI recently has been used widely for the treatment of CAD of varying extent.  In particular, it is indicated for the treatment of one-vessel CAD and two-vessel CAD with no proximal left anterior descending (LAD) artery involvement in patients who do not have diabetes mellitus. 

There are instances, however, when CABG is the preferred treatment for these lesions.  Patients who are unable to receive dual antiplatelet therapy due to side effects or poor compliance are generally considered to be poor candidates for the stent placement.

These patients can benefit from surgical revascularization.  Sometimes, anatomic considerations make PCI less favorable than surgery for revascularization of the arteries with stenoses localized at the branch points, or in vessels with excessive tortuosity.  These patients might still benefit from CABG.  

Proportion of the patients referred for coronary revascularization with diabetes mellitus had increased in the recent years.  Rates of adverse outcomes in these patients are higher than for the nondiabetics with higher risks of postoperative infections and restenosis of the grafts being problematic in particular.

Nonetheless, patients with diabetes stand to benefit from surgical coronary revascularization.  There is a strong trend for better overall outcomes for the patients with diabetes who undergo CABG compared to those who undergo PCI.

Cardiovascular disease is the major cause of mortality in patients with renal insufficiency. Fifty percent of deaths in the patients on hemodialysis are directly attributable to cardiovascular disease.

As such, patients with renal failure, or impairment are a unique subset of patients with CAD and stand to benefit significantly as a group from revascularization. However, preoperative renal insufficiency, defined as a glomerular filtration rate of less than 60 ml/hr/1.71 m2 and renal failure defined as the need for hemodialysis are major contributing factors to the increase in the postoperative morbidity and mortality in patients with CAD. 

In the situations when surgical revascularization is indicated for patients with renal insufficiency, there appears to be a survival benefit for the patients treated with CABG compared with other types of therapy. 

Patients on hemodialysis have a 20% per year mortality rate and, not surprisingly, have less convincing indications for CABG.  These patients may benefit from CABG and should be carefully evaluated on the case by case basis.

Cerebrovascular disease as the marker of atherosclerosis is present in a significant number of patients with CAD.  Recommendations for cerebrovascular and cardiovascular revascularizations when both diseases are present simultaneously are similar to the cases of disease isolated to one circulation system.

It is our practice to separate carotid endarterectomy and CABG by several days to decrease the risk of perioperative complications.  The procedure that is aimed at relief of symptoms should be performed first.  The next procedure should be performed soon (within days) after the first one.

A significant number of patients develop recurrent angina symptoms after the CABG years, or decades after the original operation. These patients might benefit from the reoperation. Reoperative CABG surgery is associated with an approximate doubling in morbidity and mortality compared with the first CABG.

A review from a large medical center with a high volume of re-do operations demonstrated in-hospital mortality of 4.3% for the first reoperation, 5.1% for the second, and 6.4% for three or more, compared with 1.5%  for primary CABG. Morbidity of re-do CABG is also significantly higher compared with the first time operations.

This increase is largely attributable to the severity of comorbidities and higher prevalence of risk factors in the repeat revascularization group, rather than to the procedure itself.  Despite higher complications and mortality risk, there appears to be a benefit for re-do CABG compared to the medical management in the cases where LIMA was not used in the initial operation,  a large portion of myocardium is at risk and good distal targets present.

CAD is the most common cause of congestive heart failure in the U.S. A combination of CAD and heart failure (HF) is associated with increased perioperative mortality. Perioperative mortality of the patients with congestive heart failure undergoing CABG is estimated to be in range of 5% to 30%.

Studies consistently show benefit in survival and improvement in left ventricular (LV) function in the patients with ischemic, but viable myocardium undergoing CABG. Patients with no viability and decreased EF (especially below 35%) are at increased risk of death and surgery therefore should be avoided.

Contraindications

There are few absolute contraindications to surgical revascularization.  It is contraindicated in the instances when the patient’s life expectancy is affected by other major comorbidities rather than progression of his CAD.

Patients with advanced cancer, severe pulmonary, or liver disease in who are not candidates for transplantation are likely not to benefit from CABG and therefore other treatment options for CAD should be entertained. 

We do not recommend surgical coronary revascularization in active alcoholics, IV drug, and cocaine abusers.

These patients commonly have difficulties following postoperative instructions and are therefore unlikely to gain full benefit from the CABG  while incurring all risks associated with major cardiac surgery. In addition, alcohol exhibits direct myocardial suppression and therefore outcomes of treatment are more dependent on the amount of alcohol consumption rather than revascularization itself.

Cocaine is a potent vasoconstrictor and can induce graft spasms that can be potentially life threatening.  Finally, drugs and alcohol withdrawals after major surgery have the potential to be life threatening. We recommend cessation of alcohol intake and drug consumption for all our patients undergoing surgery.

Several situations arise in the course of progression of the CAD that merit further discussion.  Surgery is clearly contraindicated for the patients after acute myocardial infarction (MI), with persistent angina and small or absent myocardial viability, who are stable hemodynamically.

It is also contraindicated in the setting of acute MI when there is a “no reflow” phenomenon present (successful epicardial reperfusion with unsuccessful microvascular reperfusion).  Patients with failed PCI, but with no hemodynamic compromise should not be operated on unless other indications for surgery are present.

Targets for the bypass have to be able to support the graft.  Vessels that are smaller than 1 mm in diameter are usually considered to be poor targets for the bypass and distal anastomoses to such vessels should be avoided. 

Details of how the procedure is performed

Coronary artery bypass grafting can be performed either with the use of cardiopulmonary bypass, or without the bypass support.

An incision is carried out vertically in the midline from the point midway between the sternal notch and angle of Lewis superiorly and extended to the level of the tip of xyphoid process inferiorly. The interclavicular ligament is divided at the posterior aspect of the sternal notch and a full sternotomy is performed. 

Left, right, or both internal mammary arteries are harvested by dissecting them from their take off from the subclavian arteries to the point where they bifurcate inferiorly (usually at the level of the midportion of the xyphoid process). 

At the same time, additional conduit is harvested—either greater saphenous vein or radial artery.  Multiple techniques for the conduit harvest have been described.

We use endoscopic vein harvest.  Greater saphenous vein is identified immediately preoperatively with the ultrasound performed on the operating room table.

A tunnel around the greater saphenous vein is created with a combination of CO2 insufflation and blunt dissection.  Vein tributaries are taken with cautery.

A stab incision is carried over the proximal extent of the dissection, and a vein is disconnected proximally and distally with residual vein stumps  controlled with hemoclips and ties. The vein tunnel is irrigated and closed with absorbable sutures in several layers.

The vein is prepared on the back table with all tributaries carefully controlled with surgical clips or ties.  It is flushed with heparin containing saline solution.

We perform tests to determine completeness of the palmar arterial arch preoperatively, if use of the radial artery is planned during the CABG. The radial artery is harvested from a nondominant forearm through the open incision.

All branches are controlled with clips and ties.  Care is taken to avoid injury to nerves in the forearm and other vascular structures.

The artery is flushed on the back table with heparin containing saline solution. The incision is closed in layers with absorbable sutures.

Once conduit harvest is complete, the pericardium is open from the level of the inferior border of the brachiocephalic vein to the diaphragmatic reflection of the pericardium. The pericardial incision is extended to the right and to the left of the midline to allow full access to the heart. 

Four hundred units of unfractionated heparin per kilogram of the patient's weight are administered intravenously and the activated clotting time (ACT) is allowed to rise to above 400 seconds.  The ascending aorta is cannulated through a double purse string at the level of the take-off of the brachiocephalic in the spot free of calcifications.

A two-stage venous cannula is inserted through the purse string in the right atrial appendage.  The heart is vented using the pulmonary artery vent inserted through the stab incision in the pulmonary trunk. 

The heart is cooled down to 28° to 30° C.  Once the heart is fibrillated, a crossclamp is applied to the ascending aorta and 1,000 ml of cold blood cardioplegia is administered in the antegrade fashion. 

Topical hypothermia in the pericardial well is maintained while the heart is crossclamped by continuous irrigation of the pericardial well with ice-cold normal saline solution or by application of the cooling jacket to the ventricles.

Target arteries are approached one-by-one.  Once a target artery is identified, the spot on the artery free of calcifications is chosen and encircled with silastic vessel loops for stabilization.

Epicardium is opened with the scalpel blade over the area of the planned anastomosis, making sure that the incision begins a few millimeters proximal and ends a few millimeters distal from the actual arteriotomy. Longitudinal arteriotomy is performed with a No. 15 scalpel blade and extended with angled Potts scissors for the length of approximately 4 to 6 mm.

Care is taken to avoid injury to the back wall of the vessel.  Anastomosis of the vein or arterial graft to the target vessel is performed with the running 7-0 Proline.

Prior to completion of the anastomosis, a coronary probe is used to probe the target artery distally and proximally to ensure that no obstruction is created at the heel or toe of the anastomosis.  Silastic tapes are removed and 200 ml of cold blood cardioplegia is administered in the graft in antegrade fashion. 

Anastomosis of the left internal mammary artery to the left anterior descending artery usually is performed last to avoid tearing the graft off of the target inadvertently during creation of other distal anastomoses.

Dearing maneuvers performed, and crossclamp is removed after completion of all distal anastomoses.  The patient is warmed up to normothermia.

Proximal anastomoses of the vein and arterial free grafts to the aorta are performed with the help of the side-biting clamp placed on the ascending aorta.  Aortotomies are created with the scalpel and enlarged with the help of 4 mm punch knife.

Grafts are attached to the aorta using 6-0 Prolene suture.  Grafts are deaired and opened to blood flow.

Pacing wires are placed on the right ventricle and right atrium and brought out through the skin.   Chest tubes are placed to drain the pericardial and both pleural cavities.

Patient is weaned off of cardiopulmonary bypass and hemostasis is achieved. The heparin effect is reversed with administration of an appropriate dose of protamine sulfate.

The sternum is approximated with sternal wires.  Soft tissues are closed with absorbable sutures and the patient is transferred to the intensive care unit.

Another popular technique for performing CABG is the so-called off-pump revascularization.  Special suction-assisted stabilizers are used to elevate the heart out of the pericardial well and to expose the target vessels to the surgeon.

The suction assisted immobilizer is used to provide a degree of stabilization to the target vessel.  Longitudinal arteriotomy is performed and an intravascular shunt is inserted in the target vessel to provide distal myocardial perfusion during construction of distal anastomoses. 

Traditionally left internal mammary artery anastomosis to the left anterior descending (LAD) artery target is performed first to allow immediate perfusion to the largest myocardial territory.  Technique for construction of proximal anastomoses and the remainder of the operation as well as postoperative management are the same as after performance of  the conventional CABG.

Hemodynamically stable patients without evidence of bleeding are weaned off the ventilator on the day of surgery.  Swan Ganz catheters, arterial lines, venous sheaths, and a Foley catheter are removed on postoperative day one. 

Pacing wires are removed when the patient’s rhythm is stable.  Chest tubes are removed when output decreases to 200 ml per 24-hour period, or less.

Patients are discharged home with close follow-up by the surgeon and cardiologist.

Transmyocardial revascularization is performed in the operating room under general anesthesia.  Intubation with the double lumen endotracheal tube is preferred as it allows for left lung deflation.

A left posterolateral thoracotomy is performed and a pericardium is entered. The left ventricular myocardium in the areas with impaired perfusion is selected for transmyocardial approach.

The CO2 laser is most commonly used to create transmural 1 mm in diameter channels.  Transesophageal echocardiography is employed to confirm transmurality of the channels.  Channel density should be approximately one channel per 1 cm2 of myocardium.

Areas of prior MI where myocardium is replaced by thinned out scar should be avoided.  Chest tube is placed and thoracotomy is closed in the standard fashion.

Interpretation of results

N/A

Performance characteristics of the procedure (applies only to diagnostic procedures)

N/A

Outcomes (applies only to therapeutic procedures)

CABG is shown to improve survival of patients with CAD.  Survival of patients after CABG at 5 and 10 years is approximately 90% and 75% to 80%, respectively.

It has been shown by the investigators from the Bypass Angioplasty Revascularization Investigation (BARI) trial that CABG specifically reduces mortality from sudden cardiac death in patients with CAD.

Ultimately, more than 20% of survivors would need repeat revascularization with repeat reintervention rates of 4% to 5% per year.  For the re-do operations, survival is somewhat lower, reflecting advanced age, more severe comorbidities, and additional perioperative complications.  It is estimated to be 75% and 60% at 5 and 10 years, respectively.

CABG is known to be an effective strategy for the treatment of angina.  Patients who have the surgery for relief symptoms report complete resolution of symptoms in 80% to 90% of cases.

In the report from one of the largest centers in Europe with up to 20 years of follow-up, return freedom from angina was shown to be 95%, 83%, and 63% at 1, 5, and 10 years, respectively.  Consequently, it is safe to say that a significant proportion of patients after CABG develop recurrent angina later on in the postoperative course.

Finally, CABG improves survival time and frequently improves cardiac function in patients with LV dysfunction.  It has been shown to reduce annual mortality by 12.8% in patients with 3V CAD, severely depressed LV function, and some myocardial viability.

Outcomes of revascularization are clearly dependent on the graft patency.  Several points on grafts for the coronary revascularization merit special attention.

It is a fundamental rule of the vascular bypass that patency is dependent on inflow into the graft, quality of the conduit, and availability of adequate outflow. Coronary bypasses are performed as pedicle arterial grafts with inflow originating from their normal anatomic positions, or as free graft with inflow originating from proximal aortic branches, descending thoracic aorta, or pedicle grafts. 

In general, not surprisingly, pedicle grafts have higher patency rates than the free grafts.

Different grafts demonstrate different patency rates.  Patterns of failure differ between the grafts as well. 

Vein grafts have been the most commonly employed conduit from the early stages of the development of the bypass surgery.  Vein grafts are subject to three distinct processes affecting overall patency: thrombosis, intimal hyperplasia, and atherosclerosis.

Thrombosis is most likely to occur soon after surgery and is commonly the result of a technical error in the construction of the graft (problems with proximal or distal anastomoses, or graft kinking), or due to the mistakes in the graft harvest/handling ex vivo. 

The majority of the vein grafts develop intimal hyperplasia soon (within 1 month) after the operation.  This process is usually not progressive though and results in the vein grafts approximating diameter of the target vessel at 1 year after the operation.

Most of the vein grafts eventually develop atherosclerotic changes and dilate. Atherosclerotic plaques in vein grafts are much more friable than in the native vessels and special care should be taken during manipulation of the old grafts during re-do cardiac operations and PCI to avoid distal embolization.

Overall, 10% of the vein grafts close within the first few weeks, if antiplatelet therapy is not used. Ten-year patency of the vein grafts is about 40% to 50%.  Of these, one half will have angiographic evidence of atherosclerosis.

The internal mammary artery (IMA) grafts have been shown to be very resistant to atherosclerosis.  As the result, left IMA (LIMA) patency is clearly superior to that of the other conduits with 10-year patency rates higher than 90%. Ultimately, 5% to 10% of LIMA conduits develop late stenoses, but most of these do not progress to occlusion.

Bilateral IMA use has been associated with a 16% absolute improvement in the actuarial 10-year survival time in a selected group of patients.  Use of the bilateral IMAs is associated with the higher risk of sternal wound infections as the result of impaired blood supply to the sternum.

It is not recommended in patients with other risk factors for the development of the deep sternal wound infections.

Radial arteries have been used successfully as free vascular grafts.  These grafts demonstrate 85% to 95% patency rates in the vessels with highly hemodynamically significant stenoses.

Alternative and/or additional procedures to consider

Patients with the coronary artery disease are treated with multimodality medical therapy, as well as with nonsurgical revascularization techniques, such as balloon angioplasty and stenting with both bare-metal stents and drug-eluding stents.

Medical therapy in CAD is aimed at relief of anginal symptoms,  as well as at slowing of the progression of the atherosclerosis. 

Nitrates, beta-blockers, by themselves or in combination with calcium channel blockers, lipid lowering medications, and aspirin are all employed to achieve the above mentioned goals.  Undoubtedly, most of these medication groups improve outcomes of patients with coronary artery disease. 

Lifestyle modifications such as measured physical activity, smoking cessation, and healthy diet are important aids in treatment of CAD.  Several trials addressed relative efficacy of surgical revascularization as compared with medical therapy.

Surgical revascularization strategy improved survival of patients with high and moderate risk of death from CAD, but was not shown to be beneficial in the patients with the lowest risk of mortality form CAD.

Percutaneous interventions, in the form of balloon angioplasty and implantation of various stents, aimed at restoration of coronary patency have been shown to be effective in treatment of some forms of CAD.  Multiple trials have been conducted to evaluate relative efficacy of various therapeutic modalities.

Interpretation of the results of these trials is somewhat difficult due to continuous introduction of new techniques and devices.  In general, patients undergoing PCI are enjoying faster recovery from the intervention with adequate relief of symptoms and decreased short-term mortality.

The rates of reintervention are uniformly higher after percutaneous interventions as compared to CABG.  Long-term mortality and return of anginal symptoms are lower in the patients undergoing CABG, particularly in patients with impaired left ventricular function, patients with diabetes mellitus, and patients with multivessel disease.

Percutaneous interventions are the first line of treatment for the patients in acute MI with distinct culprit lesion.  In addition, percutaneous interventions appear to be particularly useful in the treatment of atherosclerosis developing in the bypass grafts and progression of native vessel CAD after CABG.

In these circumstances, perioperative morbidity and mortality for CABG are increased and a percutaneous approach provides lower risk treatment with significant benefits.

Complications and their management

Coronary artery bypass is an extensive surgery and as such is associated with multitude of complications.  The vast majority of these complications are encountered with all other types of major surgery.

Urinary tract infections, line infections, postoperative atelectasis/pneumonias, need for prolonged ventilatory support,  deep venous thrombosis, and stress gastric ulcers happen with frequencies similar to that of other major noncardiac operations.  Their management, not surprisingly, is aimed at prevention and early recognition/aggressive intervention.

There are, however, complications that are unique to surgical revascularization. This section will focus on these complications.

Perioperative myocardial infarction (MI) happens in 3% to 6% of the patients undergoing CABG.  These patients have 2.5 times higher mortality than postoperative patients without MI. 

Prevention of perioperative MI starts in the operating room with complete revascularization and careful construction of the grafts.  Care should be exhibited in harvesting conduits as well.

Conduits should be handled gently to prevent endothelial damage and incitement of the prothrombotic state in the grafts.  Postoperatively, any significant ECG changes, or changes in the cardiac function should be worked up promptly.

Serial sampling of cardiac enzymes might be useful in establishment of the diagnosis of perioperative MI.  Echocardiograms with changes in LV wall motion, especially in combination with electrocardiogram (ECG) changes and the elevation of enzymes, should prompt further evaluation.

Our threshold for cardiac catheterization in these settings is very low.  Cardiac catheterization provides surgeons with information on patency of the grafts and state of the bypassed vessels, and can be used for percutaneous correction of some intraluminal coronary pathology.

Low cardiac output, defined as the cardiac index of less than 2.2 L/min/m2 is relatively common after the CABG.  The exact incidence is hard to determine but appears to be between 4% and 10%. 

Predictors of low cardiac output postoperatively are preoperative acute myocardial infarction, low ejection fraction, female gender,  left main coronary artery disease, three-vessel disease, and advanced age.  Treatment consists of circulatory support with an intraaortic balloon pump (IABP) and inotropes, optimization of preload/afterload, and maintenance of sinus rhythm.

Cardiac arrhythmias after CABG are common with atrial fibrillation being present in almost 40% of the patients without appropriate prophylaxis.  Perioperative beta-blockers and statins have been suggested to prevent atrial fibrillation and should be used in all the patients who can tolerate these medications. 

Atrial arrhythmias are treated postoperatively with calcium-channel blockers, high doses of magnesium, and beta-blockers.  Rate control is the predominant treatment strategy and patients are usually anticoagulated with Coumadin for prevention of thromboembolic events in cases where atrial fibrillation persists for more than 24 hours.

Neurologic complications after CABG can be divided into two groups. Type I neurologic complications are major neurologic complications ranging in severity from coma to focal neurologic deficits that last more than 24 hours.

The majority of these complications are attributed to an embolism from the sources in the ascending aorta.  Incidence of these complications varies with age and ranges from 0.5% in young patients to almost 8% in patients older than 75 years of age.

Type II neurologic complications are manifest as more subtle neurologic impairments after the CABG.  Estimates on the incidence of Type II neurologic complications vary widely, partially due to the fact that symptoms disappear rather rapidly, often within days, or weeks after the surgery.

Nonetheless, it seems that majority of the patients (up to 75% of patients in some studies) experience some sort of neurologic symptoms, such as vision disturbances, disorders of attention, decline in recent, or remote memory, and peripheral neurologic complications. Most of these complications are transient in nature, disappear rather rapidly, and do not impair patients’ quality of life.

Wound complications, particularly deep sternal wound infections, are some of the most troubling complications occurring after conventional surgical coronary revascularization.  Their incidence is estimated to be in the range of from 0.5% to 5%.

Risk factors for the development of deep sternal wound infections are diabetes mellitus, renal failure, obesity, bilateral IMA harvest, reexploration, and prolonged ventilator dependence.  Patients present with local and systemic signs of infection, frequently accompanied by sternal instability.

Treatment should be aggressive with appropriate antibiotics, resuscitation, and immediate reexploration.  Goals of surgical treatment are removal of infected material, debridement of devitalized tissue, and early coverage of the mediastinal structures by means of sternal reapproximation and/or use of the muscle flaps.

Recently vacuum-assisted closure of infected sternotomy wounds gained traction due to improved outcomes with less surgical trauma to patients.

Renal insufficiency is relatively uncommon after CABG with 6% to 7% of patients developing serum creatinine elevation levels of more than 50% as compared to the baseline.  It is transient in the majority of cases.

Less than 2% of patients with normal renal function preoperatively develop the need for renal replacement therapy postoperatively.  Mortality in patients who develop the need for dialysis is increased many fold, with some estimates suggesting mortality between 19% and 60%.

What’s the evidence? 

Hillis, LD, Smith, PK, Anderson, JL. "2011 ACCF/AHA guideline for coronary artery bypass graft surgery. A report of the American College of Cardiology Foundation/American Heart Association task force on practice guidelines. Developed in collaboration with the American Association for Thoracic Surgery, Society of Cardiovascular Anesthesiologists, and Society of Thoracic Surgeons.". J Am Coll Cardiol. vol. 58. 2011. pp. e123-210.

(Comprehensive set of guidelines for coronary artery bypass grafting that reflects current practice patterns among experts in the field of coronary revascularization in the United States.)

Wijns, W, Kolh, P, Danchin, N. "Guidelines on myocardial revascularization.". Eur Heart J. vol. 31. 2010. pp. 2501-55.

(European consensus statement on the practices of myocardial revascularization.)

Hannan, EL, Racz, MJ, McCallister, BD. "A comparison of three-year survival after coronary artery bypass graft surgery and percutaneous transluminal coronary angioplasty.". J Am Coll Cardiol. vol. 33. 1999. pp. 63-72.

(Large database evaluation showed statistically significant prolongation of survival in the patients with proximal LAD lesions and three-vessel disease with no relationship to the degree of LAD involvement.)

Allman, KC, Shaw, LJ, Hachamovitch, R. "Myocardial viability testing and impact of revascularization on prognosis in patients with coronary artery disease and left ventricular dysfunction: a meta-analysis.". J Am Coll Cardiol. vol. 39. 2002. pp. 1151-8.

(Meta-analysis of several trials with total of 3,088 patients with decreased ejection fraction. This paper demonstrated a strong association between myocardial viability on noninvasive testing and improved survival after revascularization in patients with chronic CAD and LV dysfunction. Absence of viability was associated with no significant difference in outcomes, irrespective of treatment strategy.)

Shroyer, AL, Plomondon, ME, Grover, FL. "The 1996 coronary artery bypass risk model: the Society of Thoracic Surgeons Adult Cardiac National Database.". Ann Thorac Surg. vol. 67. 1999. pp. 1205-8.

(Description of the Society of Thoracic Surgeons (STS) database based risk calculator for surgical coronary revascularization. The most current STS risk model of CABG operative mortality is a reliable and statistically valid tool.)

Edwards, FH, Clark, RE, Schwartz, M.. "Impact of internal mammary artery conduits on operative mortality in coronary revascularization.". Ann Thorac Surg. vol. 57. 1994. pp. 27-32.

(Large database study of the total of 38,578 registered patients undergoing isolated CABG from 1987 through 1991. Survival of patients with LIMA grafts was statistically higher than those without the LIMA graft.)

Sergeant, P, Blackstone, E, Meyns, B.. "Validation and interdependence with patient-variables of the influence of procedural variables on early and late survival after CABG. K.U. Leuven Coronary Surgery Program.". Eur J Cardiothorac Surg. vol. 12. 1997. pp. 1-19.

(Follow-up of patients after CABG at a single European center with one of the most comprehensive assessments of the long-term results of the CABG.)

Stone, GW, Sabik, JF, Serruys, PW. "Everolimus-eluting stents or bypass surgery for left main coronary artery disease.". N Engl J Med.. 2016.

Mäkikallio, T, Holm, NR, Lindsay, M. "Percutaneous coronary angioplasty versus coronary artery bypass grafting in treatment of unprotected left main stenosis (NOBLE): a prospective, randomised, open-label, non-inferiority trial.". Lancet.. 2016;.

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