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Coronary artery bypass grafting (CABG)
11 Coronary artery bypass grafting (CABG) J. S K O R P I L and T. H A J E K, Pilsen University Hospital,
Cardiac Centre, Czech Republic
Abstract: The developments of coronary artery bypass grafting (CABG), the fundamental surgical procedure of a cardiac surgeon’s daily practice, are outlined and CABG procedures for minimized cardiopulmonary bypass (MCPB), unfortunately a significantly less utilized option, are described. The basic concept of MCPB is a closed-loop or semi closed-loop bypass circuit driven by a centrifugal pump and these systems are at a high risk of exposure to aspiration and air embolization. The progress made in increasing de-airing capabilities and safety features is outlined and the advantages of MCPB in creating less hemodilution and low flow perfusion are explored. Recommendations are made for the meticulous surgical technique that is essential in off-pump coronary artery bypass (OPCAB) procedures, such as setting up a rapid cell saver machine or a conventional pericardial suction line in case of excessive bleeding. Results are presented from previous studies which confirm both the safety and efficacy of MCPB for a large number of cardiac patients. Key words: minimized cardiopulmonary bypass circuit, coronary artery bypass grafting.
11.1
Introduction
Surgical myocardial revascularization, which is also referred to as coronary artery revascularization and coronary artery bypass grafting (CABG), remains the fundamental surgical procedure used by cardiac surgeons for the treatment of coronary artery disease. The technique has been performed repeatedly by a number of surgeons possessing varying degrees of technical skills with predominantly good results. The basic guidelines for surgical treatment of coronary artery disease using revascularization were established by the American College of Cardiology and the American Heart Association (Table 11.1). These guidelines are based on the published results of large trials which compared surgical revascularization with medical treatment and percutaneous transluminal coronary angioplasty (PTCA). CABG has been used in clinical practice since the 1960s whereas percutaneous coronary intervention (PCI) was first introduced in 1977 by Andreas Gruentzig and, by the mid-1980s, it was promoted as an alternative to CABG. The basis of CABG is that conduits are anastomosed to a coronary vessel beyond the ‘culprit’ 176 © Woodhead Publishing Limited, 2012
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lesions, providing extra sources of nutrient blood flow to the myocardium and offering protection against the consequences of further proximal obstructive disease. In contrast, coronary stents aim to restore the normal behaviour of the native coronary vasculature without offering protection against new disease proximal to the stent. Patients and physicians need to balance the short-term convenience of the less invasive PCI procedure against the evidence-based longterm durability of the more invasive surgical revascularization.1,2 There have not been any specific guidelines for surgical myocardial revascularization on minimized cardiopulmonary bypass established until now. There are few surgical techniques for performing myocardial revascularization. Techniques using myocardial revascularization with cardiopulmonary bypass vary in terms of level of invasiveness: conventional cardiopulmonary bypass (CCPB) being more invasive and minimized cardiopulmonary bypass (MCPB) being less so. Both methods of cardiopulmonary bypass use either the old-style intermitent cross-clamp technique or, more often, cardioplegic arrest. In an emergency, they are most likely to use the empty beating heart technique. The use of CCPB, however, continues to be associated with complications that may negate an otherwise successful procedure. These complications are mainly systemic inflammatory response and coagulopathy.3–5 Partial success has been achieved using nonsurgical techniques of revascularization, such as catheter-based techniques, in combination with less invasive surgical approaches such as surgical myocardial revascularization without cardiopulmonary bypass, so called off-pump coronary artery surgery, and off-pump coronary artery bypass (OPCAB).6 Nevertheless, this technique, based on beating heart coronary surgery, plays an important role in the modern conception of CABG. Taking into account the safety and clear trend towards more complex procedures, MCPB, on the other hand, seems to represent an innovative option either for coronary surgery itself or for performing the high technical quality of CABG as well as for combined, valve, multivalve and repeat procedures.7 There have been several minimized cardiopulmonary bypass systems developed for other procedures in addition to CABG procedures.8,9 The basic concept of these devices is a closed-loop or semi closed-loop bypass circuit driven by a centrifugal pump.10 The absence of a hard-shell reservoir and the use of kinetic-assisted venous drainage expose these systems to concerns regarding the risk of aspiration and embolization. The conception of increasing de-airing capabilities and safety features has greatly improved progress in the field of mini-invasive cardiopulmonary bypass systems.10
11.2
History of coronary artery bypass grafting (CABG)
Human coronary atherosclerosis was the main disorder dealt with by cardiac surgeons throughout the 20th century. The first pioneering procedures reported by Beck were of pedicled pectoral muscle flap attached to the myocardium in order to
© Woodhead Publishing Limited, 2012
Table 11.1 American Heart Association/American College of Cardiology guidelines for CABG
Class I
© Woodhead Publishing Limited, 2012
Asymptomatic/ mild
Stable angina Unstable angina
Left main stenosis Left main equivalent (proximal LAD and proximal circumflex) Triple-vessel disease
Left main stenosis Left main equivalent (proximal LAD and proximal circumflex) Triple-vessel disease Two-vessel disease with proximal LAD stenosis and EF <50% or demonstrable ischemia One- or twovessel disease without proximal LAD stenosis but with a large territory at risk and high-risk criteria on noninvasive testing
ST segment Poor LV function elevation (Q-wave) MI
Proximal LAD None stenosis with one-vessel disease One- or twovessel disease without proximal LAD stenosis, but with a moderate territory at risk and demonstrable ischemia Ongoing ischemia despite medical therapy
Left main stenosis Left main equivalent Proximal LAD stenosis and oneto two-vessel disease
Life threatening Failed ventricular PTCA arrhythmias Left main disease Three-vessel disease
Ongoing ischemia with significant territory at risk Shock
Previous CABG
Disabling angina refractory to medical therapy Class IIa Proximal LAD stenosis and one- or twovessel disease © Woodhead Publishing Limited, 2012
Class IIb One- or twovessel disease not involving proximal LAD
Proximal LAD stenosis with one vessel disease One- or twovessel disease without proximal LAD stenosis, but with a moderate territory at risk and demonstrable ischemia
Proximal LAD stenosis and one- or twovessel disease
Ongoing ischemia despite medical therapy
One- or twovessel disease not involving the LAD
Progressive heart failure with remote territory at risk Primary reperfusion within 6–12 h
Significant viable territory and noncontractile myocardium
Bypassable one- or twovessel disease Proximal LAD disease and one- or twovessel disease
Foreign body in critical position Shock with coagulopathy and no previous sternotomy
Large territory at risk
Shock with coagulopathy and previous sternotomy
Ischemic in non-LAD distribution with a functioning LTA graft to LAD without aggressive medical or percutaneous treatment
LAD, left anterior descending branch of left main coronary artery; MI, myocardial infarction; LV, left ventricle; PTCA, percutaneous transluminal coronary angioplasty; EF, ejection fraction; LITA, left internal thoracic artery.
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provide a new blood supply.11 In 1951, Vineberg described the implantation of the internal mammary artery directly to the myocardium.12 In 1953, Gibbon used cardiopulmonary bypass for cardiac surgery for the first time.13 Surgery for coronary artery disease began in 1959 with Sabiston Jr.14 He reported the first CABG procedure, but this patient unfortunately died in the early postoperative period of a cerebrovascular accident. In 1963, Kolesov attached the left internal mammary artery to the left anterior descending artery for the first time.15 The CABG technique really began to show great potential in the late 1960s and early 1970s and became one of the most commonly performed surgical operations. It is arguably the most intensively studied surgical procedure ever undertaken. The majority of operations have been performed by using CCPB. Only a minor part of all CABG procedures were performed as OPCAB procedures. The risks of CCPB are systemic inflammatory response,1,2 and activation of the coagulation cascade3,4 as well as a significant risk of neurological complications. Systems of MCPB reduce foreign surface area and priming volume and were later developed to reduce CCPB-related side effects.7–9 The MCPB systems showed a sufficient potential to maintain total extracorporeal circulation and lower inflammatory reaction when compared with CCPB.7 The first generation of MCPB systems have not included specific de-airing capabilities which leaves a potential risk for continuous micro air embolism during perfusion.8 Additionally, an air-lock caused by disconnection or venous cannula dislocation or right atrial laceration has been difficult to manage. A new generation of MCPB, however, has been proved to provide the safe handling of large amounts of air.10 Following the first performed CABG trial of thirty patients randomly allocated to an MCPB group and compared with thirty patients randomly selected for a CCPB group, the results, reported by Fromes, demonstrate a lower inflammatory reaction in the MCPB patients.8 A group from Regensburg has also favourably reported their four years of experience with MCPB and its influence on clinical outcome.16 The records from centres favouring MCPB all over Europe in terms of quantification of CABG procedures being performed on MCPB varies from 30 to 70%. The Pilsen University Cardiac Centre has reported 70% of all their patients undergoing CABG procedure performed on MCPB.
11.3
Patient selection (indications) for mini-invasive cardiopulmonary bypass
Myocardial revascularization is appropriate when the expected benefits, in terms of survival or health outcomes (symptoms, functional status, and/or quality of life), exceed the expected negative consequences of the procedure. Therefore, risk assessment is an important aspect of deciding whether to perform this procedure. The greatest beneficiaries of surgical revascularization have been shown to be patients with severe coronary artery disease. Thus patients selected for surgical revascularization are often those with multivessel coronary disease and/or with
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severe stenosis of left main coronary artery and frequently with left ventricle dysfunction. Owing to the severe limitation of graft patency by competitive native coronary flow, only patients with coronary arteries with stenosis greater then 70% (so called significant stenosis) are recommended for bypass as well as those with a sufficient quality of coronary artery with diameter of greater than 1.3–1.5 mm. Surgical strategy is established according to coronary angiogram analysis as well as the patient’s age, medical history, conduit availability and surgeon preference. Cardiopulmonary bypass is used in approximately 75–80% of all CABG procedures, although this number varies between centres. Cardiopulmonary bypass technique is predominantly used for systemic anticoagulation. In all other procedures, the use of CCPB continues to be associated with complications that may negate an otherwise successful procedure. These previously mentioned complications of CCPB are mainly systemic inflammatory response and coagulopathy.3–5 To overcome this problem, minimized perfusion circuits (MPC) were introduced, but unfortunately they have not become a part of daily routine practice. Nevertheless, the concept of MPC shares the same philosophy with minimally invasive surgery of the preservation of physiologic integrity by minimizing the device’s related trauma. Although there have not yet been any specific guidelines postulated for surgical myocardial revascularization on minimized cardiopulmonary bypass, and bearing in mind the fact there is a certain learning curve for each individual surgeon, this technique has been recommended for elective CABG procedures for newly trained surgeons. The range of procedures performed using MPCs is steadily increasing as teams become more skilled and the general trend is slowly shifting towards their use in more urgent procedures. The goals of MPC systems are generally:
• surface and priming reduction of tubing and all components; • contact surface reduction of closed/semiclosed systems; and • heparin reduction of anti-inflammatory and anticoagulation coating systems. The priming volume of minimized circuits varies between 400 and 800 ml compared with an average of about 1500 ml in a conventional perfusion circuit. Organ perfusion depends on blood viscosity and relies on hematocrit and temperature, so perfusion pressure (mean systemic) relies on perfusion flow and blood viscosity. Hemodilution has become a crucial part of the management of extracorporeal perfusion in CCPB. The recommended level of hematocrit for CCPB procedures is maintained at 20–26%. Reports on MCPB procedures show very good results regarding the reduction of hemodilution and the inflammatory response of low flow and high hematocrit perfusion when compared with conventional circuits.17,18 There are some key features which need to be highlighted and underlined as meticulous surgical technique essential to OPCAB procedures, such as setting up a rapid cell saver machine or a conventional pericardial suction line in case of excessive bleeding. A pericardial suction line can be introduced to some types
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Air removal
Venous bubble trap
© Woodhead Publishing Limited, 2012
Remove volume Arterial filter
Electronic venous line occluder
Oxygenator
Filtered reservoir
Roller pump Accessory pack A
11.1 Pilsen University Centre of Cardiac Surgery MCPB ROCSafe RX™ configuration.
Minimized CPB techniques and technologies
Volume buffer
Centrifugal pump
182
Air bubble detector
Add volume
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of MCPB devices. It is powered by a roller pump head as, for example, in Accessory Pack A1 of MPC-ROCSafe™ manufactured by Terumo (Fig. 11.1). This can be a useful option for cell-saving systems. Blood in this case is driven to a coated flexible filtered reservoir with a pressure valve open to the atmosphere. The Accessory Pack A1 (Fig. 11.1) is favoured owing to its unbeatable set-up time and because it converts from a totally closed MPC circuit to semiclosed MPC circuit. There is an immediate blood-saving capacity ready with an optional blood reinfusion back to the venous line of MCPB if necessary, meaning that blood is aspirated by a pericardial suction line into coated Accessory Pack A (Fig. 11.1). Surgery then can be either managed routinely with a suction line on to the flexible coated Accessory Pack A or, in instances such as a closed MPC, by switching the Accessory Pack line off after all aspirated blood has been driven into it and reinfused back into the patient (strictly temporary use of pericardial suction). Nevertheless, cell saving techniques should only be used in emergency situations.
11.4
Conduits
Surgical strategy and preference of conduits is based on an intimate analysis of patient angiogram, age, medical history, target vessels, surgeon preference and conduit availability. Conduit selection consists of venous grafts, arterial grafts and a combination of both. The polytetrafluoroethylene (PTFE) conduit used as a PermaFlow system has not proven to be a promising option so far. A pedicled arterial graft has been shown to significantly improve early and late postoperative survival.19,20
11.4.1 Arterial conduits The left internal thoracic artery (LITA) is used more frequently during surgery and the right ITA (RITA) less frequently. Both are branches of subclavian arteries. The course of the ITA is approximately 3–5 cm from the mid-sternotomy line under the endothoracic fascia at the inner part of the chest wall. The ITA is an elastic type of artery giving it a high resistence to atherosclerosis. It can be used as a pedicled graft, free graft or as part of composite graft after being harvested. The LITA is the gold standard scenario of grafting the left anterior descending artery (LAD) at the anterior cardiac wall. It is also used to bypass the diagonal branch or obtuse marginal (OM) branch of the left circumflex artery, but less frequently. It can also be used as part of composite arterial graft or combined arterial/venous graft while anastomosed as a Y or T graft centrally. The 10 years’ worth of documented patency shows results which vary between 85 and 90% depending on the use of pedicled or free graft. RITA can be used as pedicled graft to the central part of the right coronary artery (RCA), or as passing RITA also as pedicled graft through a transverse sinus to reach the high marginal (HM) branch of the left circumflex artery (LCA) or as a free graft (fRITA) to any other coronary artery. Central anastomosis of fRITA is accepted to either LIMA (Y or T graft) or to the ascending aorta or any other suitable graft in cases of
© Woodhead Publishing Limited, 2012
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graft length insufficiency. Bilateral ITA is usually used in cases of polyarterial grafting or graft length insufficiency. The length of the radial artery (RA) as well as its usual diameter favours this graft despite its muscular quality which is more prone to atherosclerosis than the ITA. The preferred harvesting technique in some centres involves the use of an arteriovenous island of tissue and an ultrasound knife as well as the application of a calcium channel blockade to enhance its short-, mid- and long-term patency. A less frequently used graft is the right gastroepiploic artery (RGEA). From a biological point of view, this graft is nearly equivalent to an ITA. It is harvested in the extension of mid-sternotomy from along two thirds of the stomach greater curvature. The harvesting technique may also be facilitated by using an ultrasound knife. It is used in cases of polyarterial grafting or graft length insufficiency either pedicled (more frequently) or free graft (less frequently) as part of a composite arterial graft (Y, T graft). An infrequently used free arterial conduit is the inferior epigastric artery (IEA). It is a variable conduit in terms of diameter, length and location and is harvested from a paramedian incision beginning below the umbilicus. The rectus abdominal muscle is carefully dissected and retracted medially. The artery with accompanying veins and a small amount of tissue are dissected anteriorly, whilst the peritoneum is left posteriorly.
11.4.2 Venous conduits All vein grafts have the advantages of accessibility, availability and resistance to spasm. There are some limitations owing to length, varicosity and mismatched sizing. Additionally, the patency rate is inferior to arterial conduits. Nevertheless, the greater saphenous vein together with pedicled LITA remains the first choice for a conduit. The harvesting technique varies depending upon individual preference of each centre. Continual skin incision above the course of the vein is often replaced by a technique of multiple skin bridges or by total endoscopic vein harvesting. The quality and long term patency of the conduit is concordant with conduit deterioration when harvested. An alternative venous conduit is the lesser saphenous vein, which is usually harvested in the supine position owing to its course, which runs posterior to the lateral maleolus and follows cephalad to the popliteal fossa.
11.5
Anastomoses techniques
Variation exists in the technique of performing proximal and distal anastomoses in terms of timing with respect to distal anastomoses and aortic cross-clamp release (single cross-clamp or intermitent cross-clamp techniques). Most cardiac surgeons prefer to construct peripheral anastomoses before central anastomoses. The technique of construction performed on MCPB basically does not differ from that on CCPB; either aortotomy at the appropriate site or a running 7/0 or 8/0 suture starting,
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usually outside–in, on the conduit. Differences may be found in myocardial protection because warm blood cardioplegia (i.e. Calafiore formula) is better than cold crystaloid cardioplegia in terms of less hemodilution when performed during MCPC. However, repeating it every 20 min can be less convenient for the surgeon.21
11.6
Surgical management on mini-invasive cardiopulmonary bypass
Without any specific guidelines for surgical myocardial revascularization for minimized cardiopulmonary bypass, surgical management of CABG procedures during MCPB may differ from those for CCPB in a few modalities. MCPB creates less hemodilution and low-flow perfusion concept. The fluid management before going to MCPB may be in respect to the greater volume of crystalloid solution given by the anesthesiologist. Usually 500 or 1500 ml are given before MCPB. Both retrograde and antegrade autologous priming reduces hemodilution during MCPB. Warm-blood Calafiore formula of myocardial protection also reduces hemodilution. An infusion of 500 to 1000 ml of colloids (colloid solutions) is usually given after cross-clamp release. Owing to different de-airing and strong kinetic aspirating capability of MCPB, the author suggests applying two snare sutures around the venous cannula placed inside of the right atrium. The necessary meticulous surgical technique means that a cell-saver machine is unnecessary. Some centres, on the other hand, prefer cell saver obligatory use. Cardiotomy suction is not a constant part of MCPB but it may be applied if necessary as part of the MCPB (Accessory Pack A1 of ROCSafe by Terumo, Fig. 11.1). This converts the total closed MCPB circuit to a semiclosed MCPB circuit. Blood is then aspirated into the flexible coated reservoir of Accessory Pack A1 which has a oneway valve open to the air. Blood can be stored there during surgery or re-infused back to the patient when needed (in case of increased flow rate). Additionally, for the previously mentioned retrograde autologous blood priming, the author advises the aspiration of the blood from the aortic root using a Cooley venting line into the coated buffer volume bag (Fig. 11.1) immediately after the aorta has been cross clamped and before cardioplegia is given. This technique of left ventricle and aortic root decompression enhances the following myocardial protection and allows a reduction in the volume of cardioplegia introduced in case of cool crystalloid cardioplegia. Communication between the surgeon perfusionist and the anaesthesiologist during surgery is absolutely necessary. The surgeon may also require blood aspiration from the aortic root via the Cooley venting line intraoperatively if the left ventricle suddenly becomes overfilled or overloaded. This may happen when the venous cannula gets occluded by the inferior vena cava wall aspiration owing to negative venous pressure. This situation should be managed by stopping the pump head or reducing the perfusion flow for a short time and by decompression of the left ventricle via a Cooley venting line into a volume buffer bag (Fig. 11.1). Blood stored in the volume buffer bag (as used routinely) as
© Woodhead Publishing Limited, 2012
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Minimized CPB techniques and technologies
well as in the flexible reservoir of Accessory Pack A1 can be (author advises) reinfused back into the circulation of the patient at any time during surgery or when weaned from MCPB. Communication among the team is always required before the Cooley vent release due to possible air aspiration to the centrifugal pump head as well as in the case of any emergency situation.
11.7
Conclusions
Human coronary atherosclerosis is the main disorder dealt with by cardiac surgeons at the beginning of 21st century and coronary artery bypass grafting (CABG) still remains the fundamental surgical procedure of a cardiac surgeon’s daily practice. The main advantage of CABG is that conduits are anastomosed to coronary vessels beyond the ‘culprit’ lesions, providing extra sources of nutrient blood flow to the myocardium and offering protection against the consequences of further proximal obstructive diseases. Although specific guidelines for surgical myocardial revascularization on minimized cardiopulmonary bypass have not yet been established, procedures for MCPB may differ from those for CCPB in a few modalities. The use of CCPB continues to be associated with complications such as systemic inflammatory response and coagulopathy that may negate an otherwise successful procedure. Procedures using MCPB, on the other hand, seem to represent an innovative option either for coronary surgery itself or for performing high technical quality CABG as well as for combined, valve, multivalve and repeat procedures. There have been several mini-invasive cardiopulmonary bypass systems developed for cardiac surgery procedures. The basic concept of all these devices is a closed-loop or semiclosed-loop bypass circuit driven by a centrifugal pump. These systems are exposed to high risk of aspiration and air embolization. The conception of increasing de-airing capabilities and safety features has greatly improved progress in the field of mini-invasive cardiopulmonary bypass systems. The goals of MPC systems are generally:
• surface and priming reduction of tubing and all other components; • contact surface reduction of closed/semiclosed systems; and • heparin reduction of anti-inflammatory and anticoagulation coating systems. MCPB generally, creates less hemodilution and low-flow perfusion concept. With regard to the surgical technique of procedures performed using MCPB, there are some key features which need to be remembered and underlined as meticulous surgical technique essential to OPCAB procedures such as setting up a rapid cell saver machine or a conventional pericardial suction line in case of excessive bleeding. Usually 500 or 1500 ml of crystalloid solution are given before MCPB and about 500 to 1000 ml of colloids is given after cross-clamp release. Cardiotomy suction is not a constant part of MCPB. It can, however, be introduced if necessary as a part of a majority of MCPB (i.e. Accessory Pack A1 of ROCSafe by
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Terumo, Fig. 11.1) powered by a roller pump head. Some centres on the other hand prefer the obligatory use of a cell saver. Surgical strategy and preference of conduits is based on intimate analysis of patient angiogram, age, medical history, target vessels, surgeon preference and conduit availability. Conduit selection consists of venous grafts, arterial grafts and a combination of both. Neither conduits nor technique of construction performed using MCPB differ from those using CCPB. Communication between the surgeon, perfusionist and anaesthesiologist during surgery using MCPB is absolutely necessary. Blood stored in the volume buffer bag as well as in the flexible reservoir of Accessory Pack A1 can be reinfused back to the patient when needed or while being weaned from MCPB. Results of published trials confirm both the safety and efficacy of MCPB for a large number of cardiac patients.20,21 Minimized cardiopulmonary bypass circuits should therefore play a greater role in daily practice so that as many patients as possible can benefit from their advantages.
11.8
References
1 Pocock SJ, Henderson RA, Rickards AF, Hampton JR, King SB III, Hamm CW, Puel J, Hueb W, Goy JJ, Rodriguez A. Meta-analysis of randomised trials comparing coronary angioplasty with bypass surgery. Lancet 1995; 346: 1184–1189. 2 Three-year follow-up of the Syntax trial: Optimal revascularization strategy in patients with three-vessel disease J Am Coll Cardiol 2010; 56: B8. 3 Paparella, D, Yau, TM, Zouny, E. Cardiopulmonary bypass induced inflammation: pathophysiology and treatment. An update. Eur J Cardiothorac Surg 2002; 21: 232–244. 4 Koster, A, Fischer, T, Praus, M, et al. Hemostatic activation and inflammatory response during cardiopulmonary bypass: impact of heparin management. Anesthesiology 2002; 97: 837–841. 5 Matata, BM, Sosnowski, AW, Galinanes, M. Off-pump bypass graft operation significantly reduces oxidative stress and inflammation. Ann Thorac Surg 2000; 69: 785–791. 6 Selke, FW, DiMaio, JM, Caplan, RL et al. Comparing on-pump and off-pump coronary artery bypass grafting: numerous studies but few conclusions: a scientific statement from American Heart Association council on cardiovascular surgery and anesthesia in collaboration with the interdisciplinary working group on quality of care and outcomes research. Circulation 2005; 31: 2858–2864. 7 Kutschka, I, Skorpil, J, El Essawi, A, Hajek, T, Harringer, W. Beneficial effects of modern perfusion concepts in aortic valve and aortic root surgery. Perfusion 2009; 24: 37–44. 8 Fromes, Y, Gaillard, D, Ponzio, O, et al. Reduction of the inflammatory response following coronary bypass grafting with total minimal extracorporal circulation. Eur J Cardiothorac Surg 2002; 22: 527–533. 9 Mueller, XM, Jegger, D, Augtsburger, M, Horisberger, J, Godar, G, von Segesser, LK. A new concept of integrated cardiopulmonary bypass circuit. Eur J Cardiothorac Surg 2002; 21: 840–846. 10 Kutschka, I, Schoenrock, U, El Essawi, A, Pahari, D, Anssar, M, Harringer, W. A new minimized perfusion circuit provides highly effective ultrasound controlled de-airing. Artif Organs 2007; 31: 215–220.
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11 Beck, C. The development of a new blood supply to the heart by operation. Ann Surg 1935; 102: 801. 12 Vineberg, AM, Miller G. Internal mammary coronary anastomosis in the surgical treatment of coronary artery insufficiency. Can Med Assoc J 1951; 64: 204. 13 Gibbon, JH. Application of a mechanical heart and lung apparatus to cardiac surgery. Minn Med 1954; 37: 171. 14 Sabiston, DC Jr. Direct surgical management of congenital and acquired lesions of the coronary artery. Prog Cardiovasc Dis 1963; 6: 229. 15 Kolesov, VI. Mammary artery–coronary artery anastomosis as a method of treatment for angina pectoris. J Thorac Cardiovasc Surg 1967; 54: 535. 16 Wiesenack, C, Liebold, A, Philipp, et al. Four years’ experience with a miniaturized extracorporeal circulation system and its influence on clinical outcome. Artif. Organs 2004; 28: 1082–1088. 17 Alevizou, A, Dunning, J, Park, JD. Can a mini-bypass improve perfusion in cardiac surgery compared to conventional cardiopulmonary bypass? Interact Cardiovasc Thorac Surg 2009; 8: 457–66. 18 El Essawi, A, Hajek, T, Skorpil, J, Böning, A, Sabol, F, Hausmann, H, Ostrovsky, Y, Harringer, W. A prospective randomized multicentre clinical comparison of a minimized perfusion circuit versus conventional cardiopulmonary bypass. Eur J Cardiothorac Surg 2010; 38: 91–97. 19 Loop, FD, Lytle, BW, Cosgrove DM, et al. Influence of the internal-mammary–artery graft on 10-year survival and other cardiac events. N Engl J Med 1986; 314: 1. 20 Cameron, A, Davis, KB, Green, G, Schaff, HV. Coronary bypass surgery with internalthoracic-artery grafts – effects on survival over a 15-year period. N Engl J Med 1996; 334: 216. 21 Calafiore, AM, Teodori, G, Rondelez, L. Intermittent antegrade warm blood cardioplegia. Ann Thorac Surg 1995; 59: 398–402.
© Woodhead Publishing Limited, 2012
Cardiac Centre, Czech Republic
Abstract: The developments of coronary artery bypass grafting (CABG), the fundamental surgical procedure of a cardiac surgeon’s daily practice, are outlined and CABG procedures for minimized cardiopulmonary bypass (MCPB), unfortunately a significantly less utilized option, are described. The basic concept of MCPB is a closed-loop or semi closed-loop bypass circuit driven by a centrifugal pump and these systems are at a high risk of exposure to aspiration and air embolization. The progress made in increasing de-airing capabilities and safety features is outlined and the advantages of MCPB in creating less hemodilution and low flow perfusion are explored. Recommendations are made for the meticulous surgical technique that is essential in off-pump coronary artery bypass (OPCAB) procedures, such as setting up a rapid cell saver machine or a conventional pericardial suction line in case of excessive bleeding. Results are presented from previous studies which confirm both the safety and efficacy of MCPB for a large number of cardiac patients. Key words: minimized cardiopulmonary bypass circuit, coronary artery bypass grafting.
11.1
Introduction
Surgical myocardial revascularization, which is also referred to as coronary artery revascularization and coronary artery bypass grafting (CABG), remains the fundamental surgical procedure used by cardiac surgeons for the treatment of coronary artery disease. The technique has been performed repeatedly by a number of surgeons possessing varying degrees of technical skills with predominantly good results. The basic guidelines for surgical treatment of coronary artery disease using revascularization were established by the American College of Cardiology and the American Heart Association (Table 11.1). These guidelines are based on the published results of large trials which compared surgical revascularization with medical treatment and percutaneous transluminal coronary angioplasty (PTCA). CABG has been used in clinical practice since the 1960s whereas percutaneous coronary intervention (PCI) was first introduced in 1977 by Andreas Gruentzig and, by the mid-1980s, it was promoted as an alternative to CABG. The basis of CABG is that conduits are anastomosed to a coronary vessel beyond the ‘culprit’ 176 © Woodhead Publishing Limited, 2012
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lesions, providing extra sources of nutrient blood flow to the myocardium and offering protection against the consequences of further proximal obstructive disease. In contrast, coronary stents aim to restore the normal behaviour of the native coronary vasculature without offering protection against new disease proximal to the stent. Patients and physicians need to balance the short-term convenience of the less invasive PCI procedure against the evidence-based longterm durability of the more invasive surgical revascularization.1,2 There have not been any specific guidelines for surgical myocardial revascularization on minimized cardiopulmonary bypass established until now. There are few surgical techniques for performing myocardial revascularization. Techniques using myocardial revascularization with cardiopulmonary bypass vary in terms of level of invasiveness: conventional cardiopulmonary bypass (CCPB) being more invasive and minimized cardiopulmonary bypass (MCPB) being less so. Both methods of cardiopulmonary bypass use either the old-style intermitent cross-clamp technique or, more often, cardioplegic arrest. In an emergency, they are most likely to use the empty beating heart technique. The use of CCPB, however, continues to be associated with complications that may negate an otherwise successful procedure. These complications are mainly systemic inflammatory response and coagulopathy.3–5 Partial success has been achieved using nonsurgical techniques of revascularization, such as catheter-based techniques, in combination with less invasive surgical approaches such as surgical myocardial revascularization without cardiopulmonary bypass, so called off-pump coronary artery surgery, and off-pump coronary artery bypass (OPCAB).6 Nevertheless, this technique, based on beating heart coronary surgery, plays an important role in the modern conception of CABG. Taking into account the safety and clear trend towards more complex procedures, MCPB, on the other hand, seems to represent an innovative option either for coronary surgery itself or for performing the high technical quality of CABG as well as for combined, valve, multivalve and repeat procedures.7 There have been several minimized cardiopulmonary bypass systems developed for other procedures in addition to CABG procedures.8,9 The basic concept of these devices is a closed-loop or semi closed-loop bypass circuit driven by a centrifugal pump.10 The absence of a hard-shell reservoir and the use of kinetic-assisted venous drainage expose these systems to concerns regarding the risk of aspiration and embolization. The conception of increasing de-airing capabilities and safety features has greatly improved progress in the field of mini-invasive cardiopulmonary bypass systems.10
11.2
History of coronary artery bypass grafting (CABG)
Human coronary atherosclerosis was the main disorder dealt with by cardiac surgeons throughout the 20th century. The first pioneering procedures reported by Beck were of pedicled pectoral muscle flap attached to the myocardium in order to
© Woodhead Publishing Limited, 2012
Table 11.1 American Heart Association/American College of Cardiology guidelines for CABG
Class I
© Woodhead Publishing Limited, 2012
Asymptomatic/ mild
Stable angina Unstable angina
Left main stenosis Left main equivalent (proximal LAD and proximal circumflex) Triple-vessel disease
Left main stenosis Left main equivalent (proximal LAD and proximal circumflex) Triple-vessel disease Two-vessel disease with proximal LAD stenosis and EF <50% or demonstrable ischemia One- or twovessel disease without proximal LAD stenosis but with a large territory at risk and high-risk criteria on noninvasive testing
ST segment Poor LV function elevation (Q-wave) MI
Proximal LAD None stenosis with one-vessel disease One- or twovessel disease without proximal LAD stenosis, but with a moderate territory at risk and demonstrable ischemia Ongoing ischemia despite medical therapy
Left main stenosis Left main equivalent Proximal LAD stenosis and oneto two-vessel disease
Life threatening Failed ventricular PTCA arrhythmias Left main disease Three-vessel disease
Ongoing ischemia with significant territory at risk Shock
Previous CABG
Disabling angina refractory to medical therapy Class IIa Proximal LAD stenosis and one- or twovessel disease © Woodhead Publishing Limited, 2012
Class IIb One- or twovessel disease not involving proximal LAD
Proximal LAD stenosis with one vessel disease One- or twovessel disease without proximal LAD stenosis, but with a moderate territory at risk and demonstrable ischemia
Proximal LAD stenosis and one- or twovessel disease
Ongoing ischemia despite medical therapy
One- or twovessel disease not involving the LAD
Progressive heart failure with remote territory at risk Primary reperfusion within 6–12 h
Significant viable territory and noncontractile myocardium
Bypassable one- or twovessel disease Proximal LAD disease and one- or twovessel disease
Foreign body in critical position Shock with coagulopathy and no previous sternotomy
Large territory at risk
Shock with coagulopathy and previous sternotomy
Ischemic in non-LAD distribution with a functioning LTA graft to LAD without aggressive medical or percutaneous treatment
LAD, left anterior descending branch of left main coronary artery; MI, myocardial infarction; LV, left ventricle; PTCA, percutaneous transluminal coronary angioplasty; EF, ejection fraction; LITA, left internal thoracic artery.
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provide a new blood supply.11 In 1951, Vineberg described the implantation of the internal mammary artery directly to the myocardium.12 In 1953, Gibbon used cardiopulmonary bypass for cardiac surgery for the first time.13 Surgery for coronary artery disease began in 1959 with Sabiston Jr.14 He reported the first CABG procedure, but this patient unfortunately died in the early postoperative period of a cerebrovascular accident. In 1963, Kolesov attached the left internal mammary artery to the left anterior descending artery for the first time.15 The CABG technique really began to show great potential in the late 1960s and early 1970s and became one of the most commonly performed surgical operations. It is arguably the most intensively studied surgical procedure ever undertaken. The majority of operations have been performed by using CCPB. Only a minor part of all CABG procedures were performed as OPCAB procedures. The risks of CCPB are systemic inflammatory response,1,2 and activation of the coagulation cascade3,4 as well as a significant risk of neurological complications. Systems of MCPB reduce foreign surface area and priming volume and were later developed to reduce CCPB-related side effects.7–9 The MCPB systems showed a sufficient potential to maintain total extracorporeal circulation and lower inflammatory reaction when compared with CCPB.7 The first generation of MCPB systems have not included specific de-airing capabilities which leaves a potential risk for continuous micro air embolism during perfusion.8 Additionally, an air-lock caused by disconnection or venous cannula dislocation or right atrial laceration has been difficult to manage. A new generation of MCPB, however, has been proved to provide the safe handling of large amounts of air.10 Following the first performed CABG trial of thirty patients randomly allocated to an MCPB group and compared with thirty patients randomly selected for a CCPB group, the results, reported by Fromes, demonstrate a lower inflammatory reaction in the MCPB patients.8 A group from Regensburg has also favourably reported their four years of experience with MCPB and its influence on clinical outcome.16 The records from centres favouring MCPB all over Europe in terms of quantification of CABG procedures being performed on MCPB varies from 30 to 70%. The Pilsen University Cardiac Centre has reported 70% of all their patients undergoing CABG procedure performed on MCPB.
11.3
Patient selection (indications) for mini-invasive cardiopulmonary bypass
Myocardial revascularization is appropriate when the expected benefits, in terms of survival or health outcomes (symptoms, functional status, and/or quality of life), exceed the expected negative consequences of the procedure. Therefore, risk assessment is an important aspect of deciding whether to perform this procedure. The greatest beneficiaries of surgical revascularization have been shown to be patients with severe coronary artery disease. Thus patients selected for surgical revascularization are often those with multivessel coronary disease and/or with
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severe stenosis of left main coronary artery and frequently with left ventricle dysfunction. Owing to the severe limitation of graft patency by competitive native coronary flow, only patients with coronary arteries with stenosis greater then 70% (so called significant stenosis) are recommended for bypass as well as those with a sufficient quality of coronary artery with diameter of greater than 1.3–1.5 mm. Surgical strategy is established according to coronary angiogram analysis as well as the patient’s age, medical history, conduit availability and surgeon preference. Cardiopulmonary bypass is used in approximately 75–80% of all CABG procedures, although this number varies between centres. Cardiopulmonary bypass technique is predominantly used for systemic anticoagulation. In all other procedures, the use of CCPB continues to be associated with complications that may negate an otherwise successful procedure. These previously mentioned complications of CCPB are mainly systemic inflammatory response and coagulopathy.3–5 To overcome this problem, minimized perfusion circuits (MPC) were introduced, but unfortunately they have not become a part of daily routine practice. Nevertheless, the concept of MPC shares the same philosophy with minimally invasive surgery of the preservation of physiologic integrity by minimizing the device’s related trauma. Although there have not yet been any specific guidelines postulated for surgical myocardial revascularization on minimized cardiopulmonary bypass, and bearing in mind the fact there is a certain learning curve for each individual surgeon, this technique has been recommended for elective CABG procedures for newly trained surgeons. The range of procedures performed using MPCs is steadily increasing as teams become more skilled and the general trend is slowly shifting towards their use in more urgent procedures. The goals of MPC systems are generally:
• surface and priming reduction of tubing and all components; • contact surface reduction of closed/semiclosed systems; and • heparin reduction of anti-inflammatory and anticoagulation coating systems. The priming volume of minimized circuits varies between 400 and 800 ml compared with an average of about 1500 ml in a conventional perfusion circuit. Organ perfusion depends on blood viscosity and relies on hematocrit and temperature, so perfusion pressure (mean systemic) relies on perfusion flow and blood viscosity. Hemodilution has become a crucial part of the management of extracorporeal perfusion in CCPB. The recommended level of hematocrit for CCPB procedures is maintained at 20–26%. Reports on MCPB procedures show very good results regarding the reduction of hemodilution and the inflammatory response of low flow and high hematocrit perfusion when compared with conventional circuits.17,18 There are some key features which need to be highlighted and underlined as meticulous surgical technique essential to OPCAB procedures, such as setting up a rapid cell saver machine or a conventional pericardial suction line in case of excessive bleeding. A pericardial suction line can be introduced to some types
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Air removal
Venous bubble trap
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Remove volume Arterial filter
Electronic venous line occluder
Oxygenator
Filtered reservoir
Roller pump Accessory pack A
11.1 Pilsen University Centre of Cardiac Surgery MCPB ROCSafe RX™ configuration.
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Volume buffer
Centrifugal pump
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Air bubble detector
Add volume
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of MCPB devices. It is powered by a roller pump head as, for example, in Accessory Pack A1 of MPC-ROCSafe™ manufactured by Terumo (Fig. 11.1). This can be a useful option for cell-saving systems. Blood in this case is driven to a coated flexible filtered reservoir with a pressure valve open to the atmosphere. The Accessory Pack A1 (Fig. 11.1) is favoured owing to its unbeatable set-up time and because it converts from a totally closed MPC circuit to semiclosed MPC circuit. There is an immediate blood-saving capacity ready with an optional blood reinfusion back to the venous line of MCPB if necessary, meaning that blood is aspirated by a pericardial suction line into coated Accessory Pack A (Fig. 11.1). Surgery then can be either managed routinely with a suction line on to the flexible coated Accessory Pack A or, in instances such as a closed MPC, by switching the Accessory Pack line off after all aspirated blood has been driven into it and reinfused back into the patient (strictly temporary use of pericardial suction). Nevertheless, cell saving techniques should only be used in emergency situations.
11.4
Conduits
Surgical strategy and preference of conduits is based on an intimate analysis of patient angiogram, age, medical history, target vessels, surgeon preference and conduit availability. Conduit selection consists of venous grafts, arterial grafts and a combination of both. The polytetrafluoroethylene (PTFE) conduit used as a PermaFlow system has not proven to be a promising option so far. A pedicled arterial graft has been shown to significantly improve early and late postoperative survival.19,20
11.4.1 Arterial conduits The left internal thoracic artery (LITA) is used more frequently during surgery and the right ITA (RITA) less frequently. Both are branches of subclavian arteries. The course of the ITA is approximately 3–5 cm from the mid-sternotomy line under the endothoracic fascia at the inner part of the chest wall. The ITA is an elastic type of artery giving it a high resistence to atherosclerosis. It can be used as a pedicled graft, free graft or as part of composite graft after being harvested. The LITA is the gold standard scenario of grafting the left anterior descending artery (LAD) at the anterior cardiac wall. It is also used to bypass the diagonal branch or obtuse marginal (OM) branch of the left circumflex artery, but less frequently. It can also be used as part of composite arterial graft or combined arterial/venous graft while anastomosed as a Y or T graft centrally. The 10 years’ worth of documented patency shows results which vary between 85 and 90% depending on the use of pedicled or free graft. RITA can be used as pedicled graft to the central part of the right coronary artery (RCA), or as passing RITA also as pedicled graft through a transverse sinus to reach the high marginal (HM) branch of the left circumflex artery (LCA) or as a free graft (fRITA) to any other coronary artery. Central anastomosis of fRITA is accepted to either LIMA (Y or T graft) or to the ascending aorta or any other suitable graft in cases of
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graft length insufficiency. Bilateral ITA is usually used in cases of polyarterial grafting or graft length insufficiency. The length of the radial artery (RA) as well as its usual diameter favours this graft despite its muscular quality which is more prone to atherosclerosis than the ITA. The preferred harvesting technique in some centres involves the use of an arteriovenous island of tissue and an ultrasound knife as well as the application of a calcium channel blockade to enhance its short-, mid- and long-term patency. A less frequently used graft is the right gastroepiploic artery (RGEA). From a biological point of view, this graft is nearly equivalent to an ITA. It is harvested in the extension of mid-sternotomy from along two thirds of the stomach greater curvature. The harvesting technique may also be facilitated by using an ultrasound knife. It is used in cases of polyarterial grafting or graft length insufficiency either pedicled (more frequently) or free graft (less frequently) as part of a composite arterial graft (Y, T graft). An infrequently used free arterial conduit is the inferior epigastric artery (IEA). It is a variable conduit in terms of diameter, length and location and is harvested from a paramedian incision beginning below the umbilicus. The rectus abdominal muscle is carefully dissected and retracted medially. The artery with accompanying veins and a small amount of tissue are dissected anteriorly, whilst the peritoneum is left posteriorly.
11.4.2 Venous conduits All vein grafts have the advantages of accessibility, availability and resistance to spasm. There are some limitations owing to length, varicosity and mismatched sizing. Additionally, the patency rate is inferior to arterial conduits. Nevertheless, the greater saphenous vein together with pedicled LITA remains the first choice for a conduit. The harvesting technique varies depending upon individual preference of each centre. Continual skin incision above the course of the vein is often replaced by a technique of multiple skin bridges or by total endoscopic vein harvesting. The quality and long term patency of the conduit is concordant with conduit deterioration when harvested. An alternative venous conduit is the lesser saphenous vein, which is usually harvested in the supine position owing to its course, which runs posterior to the lateral maleolus and follows cephalad to the popliteal fossa.
11.5
Anastomoses techniques
Variation exists in the technique of performing proximal and distal anastomoses in terms of timing with respect to distal anastomoses and aortic cross-clamp release (single cross-clamp or intermitent cross-clamp techniques). Most cardiac surgeons prefer to construct peripheral anastomoses before central anastomoses. The technique of construction performed on MCPB basically does not differ from that on CCPB; either aortotomy at the appropriate site or a running 7/0 or 8/0 suture starting,
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usually outside–in, on the conduit. Differences may be found in myocardial protection because warm blood cardioplegia (i.e. Calafiore formula) is better than cold crystaloid cardioplegia in terms of less hemodilution when performed during MCPC. However, repeating it every 20 min can be less convenient for the surgeon.21
11.6
Surgical management on mini-invasive cardiopulmonary bypass
Without any specific guidelines for surgical myocardial revascularization for minimized cardiopulmonary bypass, surgical management of CABG procedures during MCPB may differ from those for CCPB in a few modalities. MCPB creates less hemodilution and low-flow perfusion concept. The fluid management before going to MCPB may be in respect to the greater volume of crystalloid solution given by the anesthesiologist. Usually 500 or 1500 ml are given before MCPB. Both retrograde and antegrade autologous priming reduces hemodilution during MCPB. Warm-blood Calafiore formula of myocardial protection also reduces hemodilution. An infusion of 500 to 1000 ml of colloids (colloid solutions) is usually given after cross-clamp release. Owing to different de-airing and strong kinetic aspirating capability of MCPB, the author suggests applying two snare sutures around the venous cannula placed inside of the right atrium. The necessary meticulous surgical technique means that a cell-saver machine is unnecessary. Some centres, on the other hand, prefer cell saver obligatory use. Cardiotomy suction is not a constant part of MCPB but it may be applied if necessary as part of the MCPB (Accessory Pack A1 of ROCSafe by Terumo, Fig. 11.1). This converts the total closed MCPB circuit to a semiclosed MCPB circuit. Blood is then aspirated into the flexible coated reservoir of Accessory Pack A1 which has a oneway valve open to the air. Blood can be stored there during surgery or re-infused back to the patient when needed (in case of increased flow rate). Additionally, for the previously mentioned retrograde autologous blood priming, the author advises the aspiration of the blood from the aortic root using a Cooley venting line into the coated buffer volume bag (Fig. 11.1) immediately after the aorta has been cross clamped and before cardioplegia is given. This technique of left ventricle and aortic root decompression enhances the following myocardial protection and allows a reduction in the volume of cardioplegia introduced in case of cool crystalloid cardioplegia. Communication between the surgeon perfusionist and the anaesthesiologist during surgery is absolutely necessary. The surgeon may also require blood aspiration from the aortic root via the Cooley venting line intraoperatively if the left ventricle suddenly becomes overfilled or overloaded. This may happen when the venous cannula gets occluded by the inferior vena cava wall aspiration owing to negative venous pressure. This situation should be managed by stopping the pump head or reducing the perfusion flow for a short time and by decompression of the left ventricle via a Cooley venting line into a volume buffer bag (Fig. 11.1). Blood stored in the volume buffer bag (as used routinely) as
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well as in the flexible reservoir of Accessory Pack A1 can be (author advises) reinfused back into the circulation of the patient at any time during surgery or when weaned from MCPB. Communication among the team is always required before the Cooley vent release due to possible air aspiration to the centrifugal pump head as well as in the case of any emergency situation.
11.7
Conclusions
Human coronary atherosclerosis is the main disorder dealt with by cardiac surgeons at the beginning of 21st century and coronary artery bypass grafting (CABG) still remains the fundamental surgical procedure of a cardiac surgeon’s daily practice. The main advantage of CABG is that conduits are anastomosed to coronary vessels beyond the ‘culprit’ lesions, providing extra sources of nutrient blood flow to the myocardium and offering protection against the consequences of further proximal obstructive diseases. Although specific guidelines for surgical myocardial revascularization on minimized cardiopulmonary bypass have not yet been established, procedures for MCPB may differ from those for CCPB in a few modalities. The use of CCPB continues to be associated with complications such as systemic inflammatory response and coagulopathy that may negate an otherwise successful procedure. Procedures using MCPB, on the other hand, seem to represent an innovative option either for coronary surgery itself or for performing high technical quality CABG as well as for combined, valve, multivalve and repeat procedures. There have been several mini-invasive cardiopulmonary bypass systems developed for cardiac surgery procedures. The basic concept of all these devices is a closed-loop or semiclosed-loop bypass circuit driven by a centrifugal pump. These systems are exposed to high risk of aspiration and air embolization. The conception of increasing de-airing capabilities and safety features has greatly improved progress in the field of mini-invasive cardiopulmonary bypass systems. The goals of MPC systems are generally:
• surface and priming reduction of tubing and all other components; • contact surface reduction of closed/semiclosed systems; and • heparin reduction of anti-inflammatory and anticoagulation coating systems. MCPB generally, creates less hemodilution and low-flow perfusion concept. With regard to the surgical technique of procedures performed using MCPB, there are some key features which need to be remembered and underlined as meticulous surgical technique essential to OPCAB procedures such as setting up a rapid cell saver machine or a conventional pericardial suction line in case of excessive bleeding. Usually 500 or 1500 ml of crystalloid solution are given before MCPB and about 500 to 1000 ml of colloids is given after cross-clamp release. Cardiotomy suction is not a constant part of MCPB. It can, however, be introduced if necessary as a part of a majority of MCPB (i.e. Accessory Pack A1 of ROCSafe by
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Terumo, Fig. 11.1) powered by a roller pump head. Some centres on the other hand prefer the obligatory use of a cell saver. Surgical strategy and preference of conduits is based on intimate analysis of patient angiogram, age, medical history, target vessels, surgeon preference and conduit availability. Conduit selection consists of venous grafts, arterial grafts and a combination of both. Neither conduits nor technique of construction performed using MCPB differ from those using CCPB. Communication between the surgeon, perfusionist and anaesthesiologist during surgery using MCPB is absolutely necessary. Blood stored in the volume buffer bag as well as in the flexible reservoir of Accessory Pack A1 can be reinfused back to the patient when needed or while being weaned from MCPB. Results of published trials confirm both the safety and efficacy of MCPB for a large number of cardiac patients.20,21 Minimized cardiopulmonary bypass circuits should therefore play a greater role in daily practice so that as many patients as possible can benefit from their advantages.
11.8
References
1 Pocock SJ, Henderson RA, Rickards AF, Hampton JR, King SB III, Hamm CW, Puel J, Hueb W, Goy JJ, Rodriguez A. Meta-analysis of randomised trials comparing coronary angioplasty with bypass surgery. Lancet 1995; 346: 1184–1189. 2 Three-year follow-up of the Syntax trial: Optimal revascularization strategy in patients with three-vessel disease J Am Coll Cardiol 2010; 56: B8. 3 Paparella, D, Yau, TM, Zouny, E. Cardiopulmonary bypass induced inflammation: pathophysiology and treatment. An update. Eur J Cardiothorac Surg 2002; 21: 232–244. 4 Koster, A, Fischer, T, Praus, M, et al. Hemostatic activation and inflammatory response during cardiopulmonary bypass: impact of heparin management. Anesthesiology 2002; 97: 837–841. 5 Matata, BM, Sosnowski, AW, Galinanes, M. Off-pump bypass graft operation significantly reduces oxidative stress and inflammation. Ann Thorac Surg 2000; 69: 785–791. 6 Selke, FW, DiMaio, JM, Caplan, RL et al. Comparing on-pump and off-pump coronary artery bypass grafting: numerous studies but few conclusions: a scientific statement from American Heart Association council on cardiovascular surgery and anesthesia in collaboration with the interdisciplinary working group on quality of care and outcomes research. Circulation 2005; 31: 2858–2864. 7 Kutschka, I, Skorpil, J, El Essawi, A, Hajek, T, Harringer, W. Beneficial effects of modern perfusion concepts in aortic valve and aortic root surgery. Perfusion 2009; 24: 37–44. 8 Fromes, Y, Gaillard, D, Ponzio, O, et al. Reduction of the inflammatory response following coronary bypass grafting with total minimal extracorporal circulation. Eur J Cardiothorac Surg 2002; 22: 527–533. 9 Mueller, XM, Jegger, D, Augtsburger, M, Horisberger, J, Godar, G, von Segesser, LK. A new concept of integrated cardiopulmonary bypass circuit. Eur J Cardiothorac Surg 2002; 21: 840–846. 10 Kutschka, I, Schoenrock, U, El Essawi, A, Pahari, D, Anssar, M, Harringer, W. A new minimized perfusion circuit provides highly effective ultrasound controlled de-airing. Artif Organs 2007; 31: 215–220.
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11 Beck, C. The development of a new blood supply to the heart by operation. Ann Surg 1935; 102: 801. 12 Vineberg, AM, Miller G. Internal mammary coronary anastomosis in the surgical treatment of coronary artery insufficiency. Can Med Assoc J 1951; 64: 204. 13 Gibbon, JH. Application of a mechanical heart and lung apparatus to cardiac surgery. Minn Med 1954; 37: 171. 14 Sabiston, DC Jr. Direct surgical management of congenital and acquired lesions of the coronary artery. Prog Cardiovasc Dis 1963; 6: 229. 15 Kolesov, VI. Mammary artery–coronary artery anastomosis as a method of treatment for angina pectoris. J Thorac Cardiovasc Surg 1967; 54: 535. 16 Wiesenack, C, Liebold, A, Philipp, et al. Four years’ experience with a miniaturized extracorporeal circulation system and its influence on clinical outcome. Artif. Organs 2004; 28: 1082–1088. 17 Alevizou, A, Dunning, J, Park, JD. Can a mini-bypass improve perfusion in cardiac surgery compared to conventional cardiopulmonary bypass? Interact Cardiovasc Thorac Surg 2009; 8: 457–66. 18 El Essawi, A, Hajek, T, Skorpil, J, Böning, A, Sabol, F, Hausmann, H, Ostrovsky, Y, Harringer, W. A prospective randomized multicentre clinical comparison of a minimized perfusion circuit versus conventional cardiopulmonary bypass. Eur J Cardiothorac Surg 2010; 38: 91–97. 19 Loop, FD, Lytle, BW, Cosgrove DM, et al. Influence of the internal-mammary–artery graft on 10-year survival and other cardiac events. N Engl J Med 1986; 314: 1. 20 Cameron, A, Davis, KB, Green, G, Schaff, HV. Coronary bypass surgery with internalthoracic-artery grafts – effects on survival over a 15-year period. N Engl J Med 1996; 334: 216. 21 Calafiore, AM, Teodori, G, Rondelez, L. Intermittent antegrade warm blood cardioplegia. Ann Thorac Surg 1995; 59: 398–402.
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