Version May 2024
INTRODUCTION — Less invasive surgical techniques using laparoscopy and robotics through smaller incisions with specialized instruments have been applied to many abdominal, urologic, and gynecologic procedures. These alternative approaches are safe and effective, resulting in a reduction in patient discomfort and hospital length of stay and cost.
There is increasing experience with the use of similar techniques to open cardiac surgery. The definitions and technical issues related to minimally invasive coronary artery bypass graft surgery (CABG) will be reviewed here. The clinical outcomes with these procedures and minimally invasive approaches to valvular surgery are discussed separately. (See "Off-pump and minimally invasive direct coronary artery bypass graft surgery: Clinical use" and "Minimally invasive aortic and mitral valve surgery".)
To appreciate the potential value of minimally invasive CABG, it is useful to first review the complications associated with standard CABG.
STANDARD CABG — Coronary artery bypass grafting (CABG), especially with the use of the left internal thoracic (mammary) artery to the left anterior descending artery (LAD) relieves symptoms, improves survival, and decreases recurrence of adverse cardiovascular events in selected groups of patients. Durability and survival may be enhanced by the use of more complete arterial revascularization, particularly in younger patients [1,2]. The alternative in patients who need revascularization is percutaneous coronary intervention (PCI), which is now usually performed with implantation of drug-eluting stents (DES). (See "Revascularization in patients with stable coronary artery disease: Coronary artery bypass graft surgery versus percutaneous coronary intervention" and "Coronary artery bypass graft surgery: Graft choices".)
The main advantages of CABG over PCI with DES are a lower rate of revascularization, correction of all coronary lesions including those that cannot easily or adequately be treated with PCI (such as chronic total occlusions and very long diffusely diseased lesions), and, in selected patients (particularly individuals with diabetes and patients with high Syntax scores), a reduction in myocardial infarction and long-term mortality. This benefit may be extended to nondiabetic patients with intermediate and high SYNTAX score [3-5]. The main disadvantage of CABG compared with PCI is its real and perceived invasiveness with its attendant longer initial recovery period (typically four to six weeks). Compared with PCI, the quality of life is similar if not superior for patients undergoing conventional CABG by one year [6-8]. (See "Coronary artery revascularization in stable patients with diabetes mellitus" and "Revascularization in patients with stable coronary artery disease: Coronary artery bypass graft surgery versus percutaneous coronary intervention".)
General principles — Several principles of surgical revascularization form a baseline against which any new technique, such as minimally invasive surgery, must be compared:
●Advances in cardiopulmonary bypass (CPB) techniques and myocardial protection, particularly in cardioplegia delivery and composition, have resulted in superior clinical results by allowing the surgeon to work in a still, quiet field with maximal visualization, permitting precise complex repair and reconstruction while protecting the myocardium. Because of the use of a cardiopulmonary bypass machine or "pump," this technique is referred to as on-pump CABG.
●The use of arterial grafting (the internal mammary or thoracic artery) to the LAD artery has reduced the incidence of graft occlusion, improved long-term survival, and decreased cardiovascular events (figure 1 and figure 2) [9]. Furthermore, more complete arterial revascularization with multiple arterial grafts using a second internal mammary artery, a radial artery, and sequential arterial grafting is recommended, particularly to left-sided coronary targets. While retrospective observational studies have shown decreased cardiac events and improved survival with multiple arterial grafting compared with a single arterial graft, this was not borne out in the five-year results of the ART trial, which compared use of single internal mammary artery with bilateral IMA [1,2,10]. (See "Coronary artery bypass graft surgery: Graft choices", section on 'Two arterial grafts'.)
●More complete revascularization, rather than a "culprit lesion" approach, has resulted in prolonged survival and reduces the need for reintervention [11,12].
Complications — The perioperative complications of CABG are discussed in detail separately. Summarized briefly, the perioperative and in-hospital mortality rate average about 1 percent for the lowest-risk elective patients, and 2 to 5 percent for all patients, and have been decreasing in the past decade [13]. However, the risk is highly dependent upon comorbid disease, postoperative complications, and the hospital volume of CABG procedures. Other important perioperative complications include myocardial infarction in 2 to 5 percent, stroke and other adverse cerebral outcomes in approximately 2 to 5 percent, renal failure, and wound infection. (See "Early noncardiac complications of coronary artery bypass graft surgery" and "Neurologic complications of cardiac surgery" and "Postoperative mediastinitis after cardiac surgery".)
Complications related to traditional techniques of cardiac surgery primarily result from the inflammatory consequences of CPB; aortic instrumentation and manipulation, including cannulation, decannulation (needed for initiation and termination of CPB), and partial or complete clamping and unclamping (needed for cardioplegic arrest and for creating proximal anastomoses), that can result in dislodgement of atherosclerotic debris and embolization from diseased aortas; and the surgical incision itself. (See "Thromboembolism from aortic plaque".)
More specifically, factors that contribute to complications include:
●Global cardiac (cardioplegic) arrest.
●Hypothermia (rarely performed except in complex arch/aortic procedures).
●Nonpulsatile bypass and artificial perfusion.
●An "inflammatory" response mediated by multiple cytokines and chemokines in which circulating leukocytes overexpress adhesion and signaling factors after contact with the artificial (nonendothelialized) surfaces of CPB; with off-pump CABG, some cytokines activated by CPB are not activated and other cytokines are activated to a similar extent but show a delayed response [14].
●The reintroduction of fat and particulate debris as well as procoagulant and proinflammatory factors from the pericardial surgical field into the systemic circulation via the use of cardiotomy (field) suction [15,16]. These can be limited by minimally invasive, closed cardiopulmonary bypass circuits, as described below [2,17,18].
●The sternotomy and skin incision and partial sternal devascularization with bilateral internal thoracic artery grafting.
Although the median sternotomy incision permits excellent visualization of all mediastinal structures, it is associated with a rate of infection (including osteomyelitis and mediastinitis) of approximately 1 to 1.5 percent. This risk is accentuated in obese, poorly controlled patients with diabetes, those with chronic obstructive pulmonary disease, or patients who actively smoke and especially when multiple risk factors are present [2,19-21]. In addition, a period of four to six weeks is required for bony union, limiting the patient's ability to resume unrestricted physical activity [22,23]. (See "Early noncardiac complications of coronary artery bypass graft surgery", section on 'Sternal wound infection and mediastinitis'.)
Newer micro-fixation systems utilizing plates and self-locking, self-drilling screws may minimize these complications, especially in higher-risk patients (such as those with obesity, diabetes, osteoporosis, smoking, and COPD) [24,25].
A variety of advances in surgical technique have been made with CABG surgery in an attempt to minimize these complications. (See "Early noncardiac complications of coronary artery bypass graft surgery", section on 'Improvements in surgical technique'.)
MINIMALLY INVASIVE CABG — Alternative approaches to the performance of standard CABG ("still heart" surgery), in which both cardiopulmonary bypass and cardioplegia are used, include: elimination of both CPB and cardioplegia; or elimination of cardioplegia only ("beating heart" surgery).
In addition, sternotomy may also be avoided, replacing it with smaller incisions. Techniques 1 or 2 are often, but, not always combined with the use of smaller incisions. These varied approaches are collectively referred to as "minimally invasive" techniques.
Surgery through smaller incisions (minimal access) and totally endoscopic "robotic" surgery requires utilization of specialized instruments or computer-enhanced tele-manipulation system [26,27]. Saphenous vein and radial artery harvest can also be accomplished through small incisions using video-based surgical techniques, decreasing the morbidity associated with leg and forearm incision (pain, infection) and permitting more rapid recovery [28-31].
The following discussion will review each of the procedures, with emphasis on advantages and disadvantages, and then the available data on clinical outcomes. The clinical outcomes with these techniques are discussed separately.
BEATING HEART CABG SURGERY — Beating heart CABG has been advocated to avoid the potential complications of both cardiopulmonary bypass (CPB) and cardioplegic arrest. Beating heart operations are performed with specialized platforms that enable myocardial surface stabilization and limit myocardial motion and by selective use of temporary endovascular shunts to limit ischemia. Using these technologies, standard and complete surgical anastomoses can be safely and effectively performed. This is known as off-pump or OP CABG.
Surgery on the beating heart poses four technical problems:
●The motion of the coronary artery hampers accurate anastomotic suturing and in particular complex revascularization (such as extensive coronary endarterectomy).
●Collateral flow from side branches may obscure the surgical view
●Temporary snaring of the coronary artery, in order to enhance visualization, may result in ischemic changes, particularly in patients with active symptoms, limited coronary collateral flow, or depressed ventricular function. Intracoronary shunts may be utilized to minimize interruption of coronary flow during construction of anastomoses. Snaring and intracoronary shunts may result in transient injury to the coronary artery.
●The heart has to be manipulated and lifted to reach posterior and lateral targets, specifically the circumflex and posterior descending arteries. The resulting anatomical distortion may lead to significant left and right ventricular hemodynamic deterioration [32]. These limitations have been addressed by devices that facilitate cardiac displacement (allowing lateral and inferior cardiac exposure) with minimal impediment to caval blood return.
Since surgery is being performed under conditions of a beating, normothermic heart, regional ischemia, particularly when collateral flow is inadequate, is possible during the 5 to 15 minutes required for construction of each anastomosis. Although this does not seem to be a frequent problem, tolerance to ischemia can be enhanced by one of the following procedures:
●Unloading the ventricle either mechanically or pharmacologically
●Direct intravascular coronary cannulation with an intravascular shunt with passive or active arterial blood perfusion of the distal myocardial bed.
●Ischemic preconditioning using intermittent repeated coronary artery occlusion prior to the definitive surgical arteriotomy. (See "Myocardial ischemic conditioning: Pathogenesis".)
Possible advantages — Off-pump CABG was developed with the intention of avoiding complications of artificial perfusion and CPB, including reductions in the inflammatory response, morbidity, and mortality. However, not all of these expected benefits have materialized. Randomized trials conducted in expert centers by experienced surgeons have failed to show a difference between on- and off-pump CABG [33,34] in terms of early mortality and major morbidity, including stroke and acute renal failure requiring hemodialysis. Non-randomized observational studies and some meta-analyses have shown an advantage of off-pump surgery in patients with extensive aortic atherosclerosis when an anaortic touch technique is used, reduced transfusion, atrial fibrillation rate, and renal dysfunction [35,36]. (See "Atrial fibrillation and flutter after cardiac surgery", section on 'Risk factors'.)
Possible disadvantages — Performing anastomoses on small disease coronary arteries is potentially less accurate. Larger randomized studies suggested greater incomplete revascularization and lower graft patency rates at one year with off-pump CABG. Meta-analyses have also shown worse mid-term survival with off-pump CABG [37-39]. In particular, when patients were matched for conduit choice, there was a significant survival advantage with on-pump CABG with divergence of survival curves after three years. Thromboembolic complications are still present with off-pump CABG, occurring in 1 percent in one review, an incidence comparable to standard CABG [40]. The risk is primarily related to instrumentation and manipulation of an atherosclerotic ascending aorta, especially with partial aortic clamping used to construct proximal anastomoses. In addition, aortic manipulation (without CPB) and partial clamping (rather than single total aortic clamping) in a diseased aorta have been associated rarely with aortic dissection [41,42]. Although rare, the frequency may be greater than seen with conventional CABG [41]. (See "Early noncardiac complications of coronary artery bypass graft surgery", section on 'Aortic dissection'.)
Two alternatives to traditional partial aortic clamping for constructions of proximal anastomoses have emerged: avoidance of all aortic manipulation or "anaortic" techniques, or devices that facilitate creation of aortic anastomoses.
Techniques that eliminate all aortic manipulation ("anaortic" techniques) create T or Y grafts for multi-vessel revascularization using the LIMA and RIMA as the inflow source. These are more easily accomplished through the median sternotomy incision that permits access to all coronary vessels and internal thoracic conduits. These are more challenging when performed through more limited anterior thoracotomy.
Newer instrumentation allows construction of proximal anastomoses without aortic partial clamping. These plug-like devices are temporarily inserted into the aorta and allow hemostasis during construction of proximal anastomosis. Stapling devices that simultaneously resect (core out) a segment of ascending aorta and create an aortic-venous proximal micro-stapled anastomosis without the need for partial aortic occlusion may address concerns of aortic manipulation injury and distal embolization [43-48]. Long-term cost efficacy data are not currently available. Preliminary data are disappointing, with a higher-than-expected rate of proximal restenosis and adverse events [45-48].
Since the operation is performed through a standard median sternotomy incision, the risk of sternal infection, malunion, and the rate of recuperation is similar to that of conventional CABG. (See "Early noncardiac complications of coronary artery bypass graft surgery", section on 'Sternal wound infection and mediastinitis'.)
As with beating heart MID CABG, snaring or instrumentation of the coronary arteries with small intra vascular shunts is required to visualize the artery when anastomosis is fashioned. This may lead to transient ischemia or vessel wall injury. Rotation or distortion of the beating heart and vena cava to allow access to the lateral and inferior coronary vessels may result in transient but significant hemodynamic dysfunction of the right and left ventricle, particularly in patients with limited reserve and extreme anatomy. Novel cardiac apical suction devices may facilitate axial rotation of the heart and expose lateral and inferior vessels with less hemodynamic consequences.
Beating heart (with CPB) — "Beating heart" CABG aims to avoid the complexity of cardiac manipulations associated with rotation of the heart to expose lateral or inferior targets for revascularization. CPB "empties" the heart and conceptually facilitates accurate coronary anastomoses by diminishing cardiac motion and facilitating retraction. Since the heart is not arrested or rendered still by cardioplegia, smaller, closed biocompatible CPB circuits are utilized that aim to limit the inflammatory and pro-thrombotic responses to traditional cardiopulmonary bypass [49,50].
NON-STERNOTOMY MID CABG WITHOUT CPB — Less invasive minimal access CABG techniques (minimally invasive direct [MID] CABG) have emphasized the use of a limited thoracotomy incision as an alternative to median sternotomy, with either direct thoracoscopic or robotic assisted left and right internal mammary artery (IMA) harvesting and direct left IMA (LIMA) to coronary artery anastomotic techniques employing myocardial stabilization (figure 3 and figure 4). Myocardial stabilization platforms improve the accuracy and ease of distal anastomosis on the beating heart [51,52].
The technique of MID CABG, performed through a limited anterior thoracotomy, is best suited to approach anterior coronary vessels, most commonly the left anterior descending artery (LAD) (figure 5). It can approach vessels that cannot be treated with PCI such as those that have excessive length, angulation, tortuosity, complex lesions, total vessel occlusion, or in-stent restenosis in a previously stented LAD, not amenable to further PCI. Concomitant procedures may be necessary to achieve complete revascularization when multi-vessel disease is present.
Depending on the technique of LIMA harvesting, the MID CABG procedures can be categorized into three main groups:
●Direct access MID CAB: In this procedure, the LIMA is harvested through an anterior thoracotomy, usually with a diathermy device. Rib-spreading is required and visualization of the proximal LIMA can be challenging. Thoracotomy and rib spreading may be associated with postoperative thoracotomy pain. Because of these limitations, there has been a general move away from the use of direct access MID CAB and they are largely performed in a few experienced centers [53].
●Thoracoscopic MID CAB: The LIMA in these operations is harvested through 5 mm thoracoscopic ports using a harmonic scalpel. There is minimal risk of thermal injury to the LIMA and the visualization of the LIMA is maintained throughout, resulting in very good flow down the LIMA and high patency of LIMA to LAD grafts. The robotic arm may be used to stabilize and manipulate the camera, followed by the LIMA-to-LAD anastomosis, performed through a small non-rib spreading incision.
This procedure is also known as EndoACAB (Endoscopic atraumatic CAB [54]). As with all minimally invasive procedures, there is a learning curve involved, and these procedures are also limited to highly expert centers.
●Robotic MID CAB: Robotic arms are used to harvest the LIMA, allowing excellent visualization and maneuverability of instruments in the thoracic cavity, resulting in very good quality of the harvested LIMA. The LIMA-to-LAD anastomosis may be performed either robotically or directly through a small non-rib spreading incision. The widespread use of this technique is also not feasible because of lack of access to robotic techniques. However, excellent results are reported by centers that use this technique routinely [55].
Once the LIMA is harvested, the pericardium is opened and cardiac motion is limited using a surface stabilizing platform that facilitates creation of accurate technical anastomoses and is designed to minimize disruption of the adjacent beating heart, thereby preserving global cardiac function (figure 6). Cardiac motion can further be limited by pharmacologic interventions that temporarily decrease the heart rate or cause transient cardiac asystole lasting several seconds. These include adenosine boluses, short-acting beta blocker therapy, or vagal stimulation. The more current generation of surface stabilizers have limited the need of adjunctive pharmacological manipulations.
Blood flow to the segment of the coronary artery chosen for anastomosis is temporarily interrupted, using specialized vessel loops that occlude the vessel. Alternatively, intracoronary shunts are placed through the opening in the coronary vessel (arteriotomy) to reestablish distal flow and prevent distal ischemia and to improve visualization while the vascular anastomosis is surgically fashioned. A direct anastomosis of the end of the arterial conduit to the side of LAD is performed using conventional techniques.
Other coronary arteries can be bypassed via different incision sites:
●The mid and distal right coronary artery can be approached through appropriately placed right anterior thoracotomy incisions, performing a distal anastomosis using the right IMA (RIMA).
●The circumflex artery and its branches can be approached through a left thoracotomy utilizing either the LIMA or the radial artery as a conduit, creating an end-to-side anastomosis (T-graft) from the LIMA to the distal coronary artery beyond the blockage [11]. Alternatively, the bypass conduit can be anastomosed directly to the descending thoracic aorta to create inflow.
●The gastroepiploic artery can be used to bypass the right coronary artery or posterior descending artery through a limited midline laparotomy incision [56,57].
Multi vessel small thoracotomy (MVST) CABG — Some expert centers, aiming to eliminate the morbidity of sternotomy, have developed techniques to perform multi-vessel revascularization through a small thoracotomy, known as MVST CABG [58,59]. This approach to more complete revascularization through a limited incision uses a free segment of the right internal thoracic artery, radial artery, saphenous vein, or inferior epigastric artery, one end of which is attached to the LIMA (which is anastomosed to the LAD) and the other end to other accessible coronary arteries (diagonal or circumflex branches) in a sequential fashion, forming "T" or "Y" grafts [60].
Possible advantages — With MID CABG, the small thoracic incisions, particularly the non-rib spreading ones, eliminate morbidity related to median sternotomy, resulting in the potential for a more rapid and complete recuperation. However, superficial wound complications still occur in up to 9 percent of patients [17].
MID CABG without CPB has primarily been used in three different groups of patients.
●A low-risk group with anterior lesions, primarily of the LAD
●High-risk patients with contraindications to conventional bypass, such as the presence of extensive ascending aortic atheromatous or calcific changes precluding safe aortic instrumentation, in whom incomplete or partial surgical revascularization is being considered (with planned hybrid PCI therapy to other coronary targets).
●MID CABG also may be useful for patients who require reoperation, but in whom a sternotomy or CPB is contraindicated or higher risk because of bypass grafts at risk, cardiac structure adherent to the sternum, previous sternal wound infection, mediastinal radiation therapy, or calcified or diffusely atherosclerotic aorta [18,61].
●Future sternotomy for other cardiac procedures in these patients may be performed with relative ease and at low risk, as there are no adhesions between the sternum and the heart/major vessels and the LIMA is away from the midline.
Possible disadvantages — The small individual incisions with MID CABG permit only limited access to specific regions of the heart, such as the anterior, lateral, and inferior walls rendering complete revascularization more technically challenging. In addition, LIMA and RIMA harvest is technically more demanding and the distal right coronary artery and the posterior descending artery, which are frequently diseased, are not easily accessed through an anterior thoracotomy incision.
Identifying and bypassing small (less than 1.5 mm) intramyocardial or diffusely diseased calcified vessels, including those with pre-existing stents, may require complex dissection and extensive endarterectomies. These procedures are best avoided with MID CABG. Patients with diffuse CAD can be identified prior to intervention by coronary angiographic data and by high resolution gated computed tomography angiography assessing endoluminal diameter and characteristics. In addition, temporary snaring of the target vessel may be poorly tolerated, particularly in patients with active ischemia, poor collaterals, and depressed ventricular function. Those patients will require intra-coronary shunts to minimize distal ischemia. Limited thoracotomy incisions are also best avoided in patients with prior left thoracotomy incisions (adhesions) or in urgent and emergency operations (unstable hemodynamics).
Proximal anastomosis to the ascending aorta is more challenging through these limited incisions. Constructing inflow to secondary graft requires a T or Y anastomosis to the IMA. These "anaortic" techniques have the advantage of eliminating aortic manipulation. Newer stapling devices have also been introduced, that facilitate creation of proximal anastomoses and may address this issue [62].
NON-STERNOTOMY MID CABG WITH CPB — MID CABG through a limited anterior thoracotomy with CPB can be performed either with a beating heart or with a still heart (cardioplegic arrest). Antegrade and retrograde cardioplegia are delivered to produce optimal myocardial protection. The surgeons can work on an empty, decompressed heart in a still and bloodless field, leading to enhanced myocardial protection and better access and freedom to manipulate and expose the entire heart, which is necessary for multi-vessel CABG.
CPB is established peripherally via cannulation of the common femoral artery and vein. Using specialized systems, an endoaortic (endovascular) balloon cross clamp is placed through the femoral arterial cannula into the ascending aorta under fluoroscopic and transesophageal echocardiographic guidance (figure 7). The LIMA is harvested under direct visualization through an appropriate small anterior thoracotomy incision. The pericardium is opened, the vessels identified, and antegrade and retrograde cardioplegic arrest is accomplished. A direct arterial anastomosis is performed using conventional techniques on the flaccid, vented, and cardioplegic heart.
Although all the regions of the heart can be approached through a limited anterior thoracotomy when the heart is arrested and decompressed, the ascending aorta is not readily accessible through this limited approach. The additional inflow required to perfuse distal targets in patients undergoing multi-vessel grafting is provided by anastomosing these conduits to the ascending aorta or T/Y grafts.
Possible advantages — As with MID CABG without CPB, this technique can approach multiple vessels that cannot be treated with PCI. Small thoracic incisions eliminate morbidity related to median sternotomy, resulting in more rapid and complete recuperation. Antegrade and retrograde cardioplegia delivery produce maximal myocardial protection. The surgeons can work on an empty, decompressed heart in a still and bloodless field, leading to enhanced technical accuracy and better access when multi-vessel CABG is necessary.
Possible disadvantages — LIMA and RIMA harvest are more technically demanding with MID CABG compared to conventional CABG with median sternotomy approach and require different instrumentation. In addition, the technique requires both aortic manipulation and conventional CPB. Since these aspects of CABG are most responsible for the inherent risk of the procedure, the thromboembolic and "inflammatory" complications are not attenuated.
Ascending aortic atherosclerosis precludes safe positioning, manipulation, and inflation of the endoaortic cross clamp, while peripheral vascular disease precludes use of femoral cannulation and safe positioning of the endoaortic balloon clamp. As a result, careful patient selection and preoperative evaluation of the aorto-ilio-femoral tree is recommended, adding cost to the procedure.
Retrograde perfusion carries a 1 to 2 percent risk of vascular complications, including distal embolization, thrombosis, or arterial dissection. Alternatively, in patients with known peripheral vascular disease, aortic cannulation or subclavian cannulation directly or through a constructed graft allows safer antegrade flow.
Because of limited access to the ascending aorta, creating proximal anastomoses is more complex and may lead to morbidity. To avoid this problem, distal grafts can be connected to the LIMA in a T- or Y-fashion, thereby creating a single and perhaps limited inflow to multiple distal targets. Alternatively, proximal grafting is performed to the subclavian artery through a second incision or ascending aorta using a partial occlusion clamp on CPB, through a second limited incision. Another approach is the use of a specialized stapling device to construct proximal anastomoses; the long-term efficacy of this approach is not yet known.
Finally, there are significant additional expenses, complexity, and added operating room costs associated with the use of these specialized systems and instruments. In addition, routine fluoroscopy, transesophageal echocardiography, specialized training, and technical experience are required.
TOTALLY ENDOSCOPIC CABG — There is limited experience with totally endoscopic coronary artery bypass graft surgery (TECAB) with using robotically-enhanced tele manipulation systems in patients with multi-vessel coronary disease [26,27]. In a literature review of robotic-assisted and TECAB procedures, early graft patency of 98.8 percent was reported after TECAB in 1604 patients. Mid-term (<5 years) and long-term (>5 years) patency rates were 95.8 and 93.6 percent, respectively [63]. The need for conversion to an open procedure fell from an initial rate of 22 percent to 5 percent in the last 20 patients; other complications also became less common. With wider availability of robotic technology, selected high volume centers are increasingly performing TECAB, both on the beating and arrested heart [64,65]. Arrested heart TECAB with robotic technology has developed sufficiently to allow complex multi-vessel CABG [66] with good early outcomes. Beating heart TECAB, which is technically more challenging, has been enabled by the use of anastomotic connectors. Studies reports graft patency of 94 percent using these connectors as well as multi-arterial grafting using the RIMA [67,68].
HYBRID CABG-PCI PROCEDURES — An emerging approach is a hybrid procedure consisting of MID CABG with a LIMA (robotic or minimally invasive harvest) to the LAD performed in conjunction with PCI using drug-eluting stents of the right coronary or left circumflex artery [69,70]. This hybrid procedure may be as effective as conventional CABG, and is associated with less perioperative morbidity [71,72]. PCI with drug-eluting stents (DES) can be performed immediately or staged shortly after CABG, with post-procedure imaging to ensure graft patency. This approach highlights the durability and survival advantage of arterial grafting, especially to the LAD, with less invasive drug-eluting stent PCI to other coronary targets, avoiding concerns over long-term patency of SVG. This view is supported by the five-year follow-up of a randomized study comparing hybrid revascularization with conventional CABG, which showed similar risks of death, MI, stroke, coronary reintervention, and MACCE in the two groups [73]. Hybrid CABG-PCI procedures should be considered, particularly in patients with risk for CPB (eg, atherosclerotic aorta, chronic obstructive pulmonary disease, renal dysfunction) in whom non-sternotomy OP CABG would be beneficial and complete revascularization (with PCI) is of benefit [19-21].
SUMMARY AND RECOMMENDATIONS
●Several alternatives to traditional cardiac surgical methods have been evaluated in an attempt to limit the morbidity associated with median sternotomy, cardiopulmonary bypass (CPB), and cardioplegic arrest. These varied approaches are referred to collectively as "minimally invasive" techniques. (See 'Standard CABG' above.)
●These techniques aim to enhance more rapid and complete post CABG procedure recuperation.
●Three alternative techniques have emerged for MID CABG, which differ in the use of CPB.
•With MID CABG through a limited anterior thoracotomy with CPB, antegrade and retrograde cardioplegia are delivered to produce optimal myocardial protection. The surgeons can work on an empty, decompressed heart in a still and bloodless field, leading to enhanced myocardial protection and better access and freedom to manipulate and expose the entire heart, which is necessary for multi-vessel CABG. This technique is now very rarely used.
•MID CAB without CPB is performed through a limited anterior thoracotomy and is best suited to approach anterior coronary vessels, most commonly the left anterior descending artery (LAD) as well as lateral (obtuse marginal) coronary targets. In this procedure, the left internal mammary artery (LIMA) is anastomosed to the LAD and lateral grafts are typically fashioned as Y or T grafts off the LIMA with either saphenous vein or additional arterial grafts. These procedures may be performed through direct access, endoscopically, or robotic-assisted.
•Multi-vessel minimally invasive CABG can be performed either through a small thoracotomy or totally endoscopic either on the beating or arrested heart with comparable outcomes to conventional CABG and advantages of minimally invasive access.
•Hybrid MID CABG (no CPB) with LIMA to LAD and percutaneous coronary intervention with drug-eluting stents to treat residual significant CAD. This emerging therapy is particularly attractive in patients with significant co-morbidities.
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