Off-pump coronary artery bypass graft (OPCAB) constitutes

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1 Off-Pump Coronary Artery Bypass Grafting Bobby Yanagawa *, and John D. Puskas Off-pump coronary artery bypass graft (OPCAB) constitutes a minority of surgical revascularization procedures performed world wide, but it remains an important tool in the surgical armamentarium. If surgeons can achieve a comparable quality of anastomosis and completeness of revascularization as an on-pump procedure, OPCAB has the potential to reduce in-hospital morbidity and mortality in select high-risk patients. In this review, we describe our operative technique for OPCAB including perioperative medical management, the use of intraoperative imaging to reduce the risk of stroke, the optimal use of adjuncts to achieve a near bloodless field to allow for the creation of a precise and reproducible anastomosis and specialized tools to confirm graft flow. Operative Techniques in Thoracic and Cardiovasculary Surgery 21:2-19 r 2016 Published by Elsevier Inc. KEYWORDS off-pump coronary artery bypass graft, cardiopulmonary bypass, total arterial revascularization, complete revascularization Introduction Off-pump coronary artery bypass graft (OPCAB) constitutes a minority of coronary artery bypass grafting procedures performed worldwide, but it remains an important tool for surgical revascularization. 1 The lack of broad adoption is primarily owing to the greater technical difficulty, the lack of clear mortality benefit in large randomized controlled trials and the suggestion of poorer long-term graft patency outcomes in some series. 2-5 For specialized surgeons, if complete revascularization can consistently be accomplished by OPCAB, then the morbidity attributable to aortic cannulation and clamping, cardioplegia, and the use of cardiopulmonary bypass would be avoided and the patient should benefit. For select high-risk patients such as those with a porcelain aorta, OPCAB is absolutely necessary to accomplish surgical revascularization. There are also vulnerable, high-risk patient cohorts such as women, those with dialysis-dependent renal failure, advanced age, and previous stroke or cerebrovascular disease who can benefit from an off-pump procedure. 6-8 Thus, OPCAB remains relevant for surgical revasculatization and every tertiary cardiac surgical program should have at least one surgeon who is facile at off-pump surgery. A few points regarding our OPCAB protocol deserve mention. We give aspirin 325 mg PO on the night before surgery and another 325 mg is given per rectum after *Division of Cardiac Surgery, St Michael's Hospital, Toronto, Canada Department of Cardiothoracic Surgery, Icahn School of Medicine at Mount Sinai, Mount Sinai Beth Israel, New York, NY Address reprint requests to John D. Puskas, MD, Department of Cardiothoracic Surgery, Icahn School of Medicine at Mount Sinai, Mount Sinai Beth Israel, New York, NY. john.puskas@mountsinai.org /$-see front matter r 2016 Published by Elsevier Inc. anesthetic induction in the operating room. Regarding anticoagulation, we use an initial half dose of heparin intravenous (1.5 mg/kg) 3 minutes before the internal thoracic artery is divided and maintain a continuous infusion of heparin 6000 units/h to keep the activated clotting time 4300 seconds. During the procedure, the patient is kept normothermic to avoid platelet dysfunction and ventricular arrhythmias with the use of intravenous fluid warmers, warmed inhalational anesthetic agents, maintenance of warm operating room temperatures, and by the use of a convective forced-air warming Bair Hugger system (Arizant Healthcare, Eden Prairie, MN) underneath the patient. Operative Technique The operative technique is described in detail as shown in Figures There are a few final technical points that deserve mention. Some patient-related factors can make an OPCAB procedure very challenging and they include multiple basal lateral wall targets, cardiomegally, severe left ventricular dysfunction, intramyocardial coronary arteries, especially in high lateral wall targets, small or diffusely diseased coronary arteries, anticipated need for endarterectomy or plasty, aortic or mitral regurgitation, hemodynamic instability, pulmonary hypertension, left main coronary artery disease, or ischemic arrhythmia. Graft sequence in OPCAB should be individualized for each patient. As a general rule (1) the left anterior descending should be bypassed first in high-risk patients, as it can be exposed with minimal manipulation of the heart. (2) Completely occluded vessels can be revascularized with low risk of incremental ischemia. (3) Collateralized vessel (s) should be grafted before collateralizing vessels. (4) A

2 OPCAB 3 short left internal thoracic artery-left anterior descending graft may require that this distal anastomosis be performed after lateral wall grafting to avoid undue tension on the left internal thoracic artery graft during lateral displacement of the heart. We routinely perform intraoperative assessment of the aorta with transesophageal echocardiography, manual palpation, and epiaortic ultrasonography. Once bypasses are constructed, we routinely quantitate flow using an intraoperative transit-time doppler flow meter (Medistim, Oslo, Norway). Acceptable values are flow 415 ml/min, pulsatility index o5, and diastolic fraction 450% for left-sided grafts. Any values outside of this range should prompt careful examination of the anastomoses (including with high-resolution epivascular ultrasound imaging) and graft and consideration of revision. We do not accept suboptimal doppler results and revise or reconstruct either the distal or proximal anastomosis, unless characteristics of the conduit or native coronary artery can readily account for the doppler findings. Compared with on-pump coronary artery bypass grafting with full-dose heparin and pump-associated platelet dysfunction and consumptive coagulopathy, patients undergoing OPCAB are relatively hypercoagulable owing to activation of an intact coagulation cascade and platelet function. For this reason, we use dual antiplatelet therapy with aspirin and plavix for 6 months post-opcab, then aspirin continued for life. We administer aspirin (162 mg) and clopidogrel (150 mg) either PO or per nasogastric tube, 2-6 hours postoperatively. In patients with high-volume chest tube drainage immediately after surgery, dual antiplatelet therapy is delayed until bleeding is minimal. Thereafter, clopidogrel 75 mg PO is administered daily for 6 months and aspirin 162 mg PO daily for life.

3 4 B. Yanagawa and J.D. Puskas A Pleura opened with harmonic scalpel for access to RITA B RITA partially isolated C Back edge of hook harmonic scalpel ligating intercostal branches Figure 1 The ITA(s) are harvested as skeletonized grafts using a Harmonic Scalpel (Harmonic Synergy, Ethicon, Somerville, NJ) to minimize sternal injury. The endothoracic fascia can be cut using the hook blade (A) and the mammary branches can be coagulated by gently oscillating the broad edge of the scalpel against the branch (B and C). RITA=right internal thoracic artery.

4 OPCAB 5 Harvesting right radial artery Figure 2 The radial arteries are harvested as a pedicle by endoscopic technique. If bilateral radial arteries are harvested, then the femoral artery is used for invasive arterial pressure monitoring.

5 6 B. Yanagawa and J.D. Puskas A Aorta SVC Pulmonary arteries Left pulmonary veins Left phrenic n. Right phrenic n. Right pulmonary veins IVC 2/3 1/3 Snare tube placed over pericardial stitch & positioned for exposure of posterior wall of heart Figure 3 OPCAB pericardial retraction. Our initial pericardial maneuvers include wide pericardiotomy, freeing the left and right pericardium from the diaphragm. The left lateral pericardial incision is extended to the apex, which is essential to allow the pericardium to be fully retracted, displacing the heart, and exposing the lateral wall of the left ventricle. The right pericardium is also dissected along the diaphragm to allow the heart to fall into the right chest during lateral displacement and the right pleura may even be opened for very large hearts. It is vital to avoid trauma to either phrenic nerve, by directly visualizing the nerves and avoiding traction or electrocautery injury. (A) We elevate the right sternal edge with rolled towels. We use a single deep pericardial traction suture placed approximately two-thirds of the way between the inferior vena cava and left inferior pulmonary vein at the point where the pericardium reflects over the posterior left atrium. This suture is covered with a soft rubber catheter to prevent abrasion of the epicardium.

6 OPCAB 7 B Tubed traction stitches positioned for exposure of left wall Pulmonary arteries Right superior pulmonary vein Figure 3 Continued (B) The pericardial traction suture is directed leftward to further aid rightward displacement of the heart during left lateral wall exposure or (C) inferiorly for exposure of the inferior wall.

7 8 B. Yanagawa and J.D. Puskas C Apex Middle cardiac v & posterior interventricular artery Circumflex br of left coronary a. Right coronary a. Coronary sinus IVC Figure 3 Continued.

8 OPCAB 9 Stabilizer on anterior heart Figure 4 Anterior wall positioning: place the patient in gentle Trendelenburg position to maintain adequate cardiac filling during cardiac displacement. The single deep pericardial traction suture is pulled toward the patient s left hip to elevate the heart up and out of the pericardial well with little change in hemodynamics. The coronary stabilization device (Octopus Tissue Stabilizer, Medtronic) should be placed on the caudal aspect of the retractor. The stabilizer should be centered around the target vessel with minimal tension on the epicardium and the malleable pods may be curved, bent together or apart, and rotated to optimize epicardial tissue capture and subsequent coronary stabilization.

9 10 B. Yanagawa and J.D. Puskas Starfish traction on apex for exposure of inferior wall Pericardial snare for increased elevation for heart from pericardial bed Figure 5 Inferior wall positioning: place the patient in steep Trendelenburg position to expose the inferior wall and to augment preload. The cardiac positioning device (Starfish Heart Positioner, Medtronic, Minneapolis, MN) attaches to the retractor (OctoBase, Medtronic or Acrobat, Maquet or other available devices) and is placed on the apex to elevate the heart vertically to expose the posterior descending artery and on the acute margin to expose the mid-rca or distal-rca. The coronary stabilizer is placed on the right or left side of the retractor. Avoid unnecessary compression with these coronary stabilizers, as paradoxically, this would lead to both more motion of the coronary target and worse hemodynamic stability. When encircling the posterior descending artery, the silastic vessel loop is pulled down using a pulley created with a silk stitch on the pericardial diaphragmatic surface to aid in target vessel exposure. RCA=right coronary artery.

10 OPCAB 11 Apex rotated into right chest for exposure of left lateral wall Figure 6 Lateral wall positioning: place the patient in steep Trendelenburg position to optimize preload by autotransfusion and turn the table sharply toward the right to expose the lateral wall. Apply the cardiac positioning device to the anterolateral wall of the heart ( off-apex ) and roll the apex of the heart under the right sternal border without much vertical lift to expose the lateral wall targets. (This requires that the right pleural cavity be widely opened, the right-sided pericardial traction sutures be released, and the right limb of the sternal retractor be elevated on rolled towels). Place the device on the lateral wall for ramus intermedius and high obtuse marginal targets. Patience is needed to achieve the optimal exposure while ensuring hemodynamic stability. Displace the heart slowly and incrementally with the use of suction devices, traction sutures, table rotation and tilt, and gravity. As a rule, the heart tolerates rotation but not compression. The coronary stabilizer is placed on the right side of the retractor for lateral wall exposure and coronary stabilization.

11 12 B. Yanagawa and J.D. Puskas Distal end-to-side anastomosis of LITA to LAD LITA graft Silastic loop on proximal LAD Mister/blower Figure 7 Distal anastomosis: we suggest that a stable systolic blood pressure of greater than 90 mm Hg be obtained before starting an anastomosis. A silastic tape with blunted needle (Quest Medical, Inc, Allen, TX) is used to encircle the target vessel proximally, taking a generous amount of tissue within the arc of the silastic tape needle to avoid injury to the coronary artery. Only rarely do we apply a second silastic vessel loop around the coronary artery target vessel distal to the planned anastomotic site to avoid any risk of injury to the distal vessel. An arteriotomy is made and the coronary anastomosis is performed using an 8-0 polypropylene suture. The immediate field is kept free of blood with a warm, humidified, ph-balanced fluid, and CO 2 blower. The assistant should direct the blower jet into or onto the coronary artery only while sutures are being placed to avoid complications that may occur with excessive use of the blower such as endothelial injury or vessel wall dissection. The 8-0 needles are always passed from inside to outside on the native coronary artery to avoid disrupting or lifting coronary atherosclerotic plaque.

12 OPCAB 13 Pulley stitch Figure 8 Inferior silastic pulley. For inferior wall coronary targets, the silastic suture can be displaced posteriorly and caudally by tying a more posterior pericardial suture loosely around the retractor tape to act as a pulley to further improve target vessel exposure.

13 14 B. Yanagawa and J.D. Puskas A Heartstring aortic punch MAOUET 3.8mm Figure 9 We routinely perform our proximal anastomoses with a proximal anastomosis device (Heartstring III Proximal Seal System; Maquet, Rastatt, Germany). Epiaortic ultrasound is performed for assessment of atherosclerotic disease of the ascending aorta that is not manually palpable. (A) An aortotomy can be made with a 3.8 or 4.3-mm aortic punch, (B) the device is deployed, and (C) the proximal anastomosis is performed using 6-0 polypropylene suture. After completion of the anastomosis, the device is removed by unwinding the sealing cup from the aorta before tying down the suture. After the suture is tied down, vein grafts can be deaired with a 25-gauge needle. Arterial grafts are allowed to bleed backward before Heartstring removal (D).

14 OPCAB 15 B Insertion of Heartstring Figure 9 Continued.

15 16 B. Yanagawa and J.D. Puskas C Proximal anastomosis with Heartstring clampless facilitating device Figure 9 Continued.

16 OPCAB 17 D CABG complete Figure 9 Continued.

17 18 B. Yanagawa and J.D. Puskas Radial artery graft from aorta to right coronary artery Composite RITA gaft to posteriolateral obtuse marginal coronary artery LITA graft to LAD Figure 10 A common total arterial graft configuration for 3-vessel disease.

18 OPCAB 19 Conclusions OPCAB is a highly specialized technique with the potential for reduction of in-hospital morbidity and mortality, particularly in high-risk patient population groups. These benefits are likely owing to avoiding cardiopulmonary bypass and minimizing aortic manipulation. We strive to optimize the use of stabilizers and positioning devices to achieve vessel exposure that is comparable with an on-pump case. By doing so, we believe that we can achieve equivalent quality of anastomosis, completeness of revascularization, and graft patency. References 1. Bakaeen FG, Shroyer AL, Gammie JS, et al: Trends in use of off-pump coronary artery bypass grafting: Results from the Society of Thoracic Surgeons Adult Cardiac Surgery Database. J Thorac Cardiovasc Surg 148:856-3, Shroyer AL, Grover FL, Hattler B, et al: Veterans Affairs Randomized On/ Off Bypass (ROOBY) Study Group. On-pump versus off-pump coronaryartery bypass surgery. N Engl J Med 361: , Lamy A, Devereaux PJ, Prabhakaran D, et al: Effects of off-pump and onpump coronary-artery bypass grafting at 1 year. N Engl J Med 368: , Diegeler A, Börgermann J, Kappert U, et al: Off-pump versus on-pump coronary-artery bypass grafting in elderly patients. N Engl J Med 368: , Puskas JD, Martin J, Cheng DC, et al: ISMICS consensus conference and statements of randomized controlled trials of off-pump versus conventional coronary artery bypass surgery. Innovations (Phila) 10: , Puskas JD, Edwards FH, Pappas PA, et al: Off-pump techniques benefit men and women and narrow the disparity in mortality after coronary bypass grafting. Ann Thorac Surg 84: , Puskas JD, Thourani VH, Kilgo P, et al: Off-pump coronary artery bypass disproportionately benefits high-risk patients. Ann Thorac Surg 88: , Polomsky M, He X, O Brien SM, et al: Outcomes of off-pump versus on-pump coronary artery bypass grafting: Impact of preoperative risk. J Thorac Cardiovasc Surg 145: , 2013