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Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Author's personal copy Review REVIEW On-pump Beating Heart Surgery Ansheng Mo, MD a,∗ and Hui Lin, MD a,b a Department of Cardiothoracic Surgery, The People’s Hospital of Guangxi Zhuang Autonomous Region, Nanning 530021, China b The People’s Hospital of Wuhan University, Wuhan, China On-pump beating heart surgery has been proposed as a superior technique for cardiac surgery, and is receiving renewed interest from cardiac surgeons. Here, we review the technique, focusing on the basic principles of myocardial protection, operative methodology, category, intraoperative concerns, current status, organ protection, advantages, disadvantages, indications, contraindications, unanswered questions, and future research. (Heart, Lung and Circulation 2011;20:295–304) © 2011 Australasian Society of Cardiac and Thoracic Surgeons and the Cardiac Society of Australia and New Zealand. Published by Elsevier Inc. All rights reserved. Keywords. On-pump; Beating heart; Ischaemia–reperfusion Introduction Feasibility of Surgery on the Empty Beating Heart ardiac surgery was performed under beating heart Myocardial Protection C or ventricular fibrillation conditions prior to the During on-pump beating heart surgery, the oxygen advent of cardioplegia, which made surgery easier. How- consumption of the empty beating heart decreases to ever, inadequate preservation of myocardial function was about 50% at normothermia [7]. The application of mild ◦ largely responsible for mortality and morbidity after car- hypothermia (32–35 C) can reduce oxygen consumption diac surgery. Avoidance of the adverse consequences of by an additional 5–20% [8]. Oxygen supply to the empty cardioplegia has been the driving force behind the devel- beating heart is adequate at a perfusion pressure of opment of on-pump beating heart surgery. 40–70 mm Hg and a flow of 0.8–1 mL/g heart muscle per Lillehei and colleagues successfully performed intrac- minute [9]. ardiac surgery on empty beating hearts, using cross- circulation in 1952, and reported a clinical case of aortic Operability valve surgery using the on-pump beating heart tech- After tightening caval snares and maintaining the left nique in 1956 [1,2]. In 1960, Starr et al. performed aortic ventricle vented to the atmosphere, cardiac pre-load and valve replacement for the beating heart under cardiopul- post-load can be considered equal to zero; according to the monary bypass [3]; in 1965, McGoon et al. reported a Frank–Starling mechanism, reduction in heart inotropy series of 100 consecutive aortic valve replacements, using can be achieved. In addition, mild hypothermia fur- the beating heart technique [4]; and in 1976, Eyster et al. ther diminishes contractile function [10] and decreases inserted a mitral valve prosthesis for the correction of the heart rate by 50% [11]. Injection of esmolol further mitral regurgitation in a dog using the on-pump beating decreases heart rate and inotropy [12,13]. An empty beat- heart technique [5]. Although these early procedures were ing heart coupled with the use of esmolol is sufficient to performed on beating hearts, the advent of the favoured decrease heart rate and inotropy safely, and to perform arrested heart surgery changed the way these surgeries cardiac surgery conveniently. were performed. In 1991, Lichtenstein et al. suggested that warm-heart surgery could enhance perioperative myocar- dial metabolic function [6], renewing the interest of cardiac Anaesthesia surgeons in on-pump beating heart surgery. Here, we review this technique. Anaesthetic considerations for cardiac surgery on an empty beating heart are focused on the maintenance of the beating state of the heart, including strict control of elec- trolyte balance and maintenance of adequate perfusion Received 1 September 2010; received in revised form 16 January pressure. 2011; accepted 24 January 2011; available online 16 February 2011 ∗ Corresponding author at: No. 6 Taoyuan Road, Nanning City, Cardiopulmonary Bypass Guangxi Zhuang Autonomous Region, China. Tel.: +86 0771 2186312; fax: +86 0771 2802018. After accomplishing adequate anticoagulation, cardiopul- E-mail address: [email protected] (A. Mo). monary bypass is instituted. During the period of © 2011 Australasian Society of Cardiac and Thoracic Surgeons and the Cardiac Society of 1443-9506/04/$36.00 Australia and New Zealand. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.hlc.2011.01.021 Author's personal copy 296 Mo and Lin Heart, Lung and Circulation On-pump Beating Heart Surgery 2011;20:295–304 REVIEW cardiopulmonary bypass, the mean arterial blood pres- Simultaneous Aortic and Coronary Sinus Perfusion sure is maintained within the range of 50–80 mm Hg at a With Aortic Cross-clamping (Fig. 3A) flow rate of 2.2–3.4 L/m2/min [14,15]; the perfusate temper- ◦ Systemic perfusion and heart perfusion employ different ature is adjusted to maintain temperature at 32–37 C; the perfusion systems. In heart perfusion, a cannula is placed haematocrit is maintained at 18–24% in mild hypothermia into the aorta and another cannula is inserted into the [14] and >20% in normothermia [16]. coronary sinus. Both cannulas are connected to a Y-tube attached to the cardiopulmonary bypass circuit [23,24]. Heart Perfusion Simultaneous Aortic and Coronary Sinus Perfusion Antegrade Perfusion via Aortic Root Without Aortic Without Aortic Cross-clamping (Fig. 3B) Cross-clamping (Fig. 1A) Continuous coronary perfusion is provided via retrograde This method of antegrade delivery [14,17–19] is suitable coronary sinus perfusion in an unclamped aorta. There- for any type of intracardiac or extracardiac repair except fore, the coronary ostia are perfused with blood from aortic root and/or aortic valve procedures, or cases of an ascending aortic cannula, and the coronary sinus is aortic insufficiency. In order to reduce the incidence of aor- perfused from a pump connected to the oxygenator. The tic insufficiency caused by mitral retraction, a transseptal advantage of this perfusion technique is that it allows for approach is recommended when performing mitral valve safer myocardial protection, should one system fail [25]. procedures. Simultaneous Coronary Ostia and Coronary Sinus Antegrade Perfusion via Aortic Root With Aortic Perfusion (Fig. 3C) Cross-clamping (Fig. 1B) Antegrade flow is maintained at approximately A cross-clamp is used between the two perfusion cannu- 100 mL/min with a line pressure of 200 mm Hg, but las, and the pressure of the proximal segment of the aortic the pressure in the coronary ostia system is the same root is maintained at 40–70 mm Hg [9,13]. This heart per- as the systemic blood pressure (usually 70 mm Hg mean fusion pattern may be an optimal method to reduce the pressure); simultaneous retrograde flow is 75–100 mL/min risk of air embolism, providing better myocardial protec- with a coronary sinus pressure of 50 mm Hg [26]. tion and facilitating surgery [9,12,13]. This method has a similar application as antegrade perfusion via the aortic Simultaneous Left Coronary Ostium and Coronary root without aortic cross-clamping. Sinus Perfusion (Fig. 3D) A cannula is introduced into the left coronary ostium after Antegrade Perfusion via Selective Cannulation of the aortotomy, and the coronary ostium is infused at a rate of Coronary Ostia (Fig. 1C) 300 mL/min. Meanwhile, the coronary sinus is perfused at Direct cannulation of the coronary ostia using a Jehler a rate of 200 mL/min to maintain the mean distal catheter coronary perfusion cannula allows continuous perfusion pressure at 55 mm Hg once the aorta is cross-clamped [27]. with oxygenated blood at a rate of 200–300 mL/min [20]. The disadvantages of direct antegrade perfusion include risk of ostial injury, postcannulation ostial stenosis, and Intraoperative Concerns interruption of surgical procedures. However, the devel- Maintaining Adequate Coronary Perfusion opment of coronary perfusion cannula may reduce the Maintaining adequate coronary perfusion is very impor- incidence of postcannulation ostial stenosis with direct tant for maintaining the heart beat. Consequently, cannulation of the coronary ostia using a soft and appro- the perfusion catheter must be in place throughout priately sized cannula. the procedure. In antegrade perfusion, a rate flow of 0.8–1.0 mL/g heart muscle/min assures heart perfusion Antegrade Perfusion via Coronary Bypass Grafts adequacy [9]. In retrograde perfusion, a perfusion pres- (Fig. 1D) sure of 45–60 mm Hg with a flow rate of 200–500 mL/min When coronary artery bypass grafts allow the heart to is enough to supply myocardial oxygen in an empty beat- be perfused adequately, the aorta is cross-clamped below ing state [28–31]. One study reported on the recovery of the level of proximal graft anastomoses. This technique sinus rhythm with a maximum flow rate of 650 mL/min, greatly depends on the quality of the aorta at the site of the and maintenance of sinus rhythm with a flow rate of proposed cross-clamping and the disposition of previous 650 mL/min and a coronary sinus mean pressure of less vein grafts on the ascending aorta [21]. than 120 mm Hg [32]. The optimal flow rate of retrograde perfusion of the beating heart under normal tempera- Retrograde Perfusion via the Coronary Sinus (Fig. 2) ture has been suggested to be 7.0 mL/kg/min [33]. For In retrograde perfusion, the heart is perfused via the coro- simultaneous perfusion, the antegrade perfusion pressure nary sinus, and the blood drains via the coronary ostia.