History of off-pump coronary artery bypass surgery

The history of off-pump coronary artery bypass surgery (OPCAB) goes back to the early 1900s, when surgical procedures to treat angina and myocardial ischemia were limited to cardiac denervation and total or subtotal thyroidectomy. During the 1930s, pioneers such as Beck , Robertson , Gross , and Roberts developed initial techniques of indirect myocardial revascularization, which included procedures that promoted myocardial neo-vascularization by direct contact with other vascularized tissues , and improvement in myocardial retrograde oxygenation by arterialization of the coronary sinus . In 1946 Dr. Vineberg from McGill University published the findings of the first procedure in which the internal mammary artery (IMA) was directly embedded into the cardiac muscle; a technique that, as demonstrated by Sones’s coronary arteriography in 1962, induced the formation of myocardial collateral circulation between the implanted systemic artery and the coronary vessels. This technique became known as the Vineberg Operation and was adopted until the early 1970s to treat angina.

It was in the 1950s when the first reports of direct coronary artery bypass grafting (CABG) attempts emerged and became an important matter of research . The bases of OPCAB were established by the experimental studies reported by Murray and Demikhov ; the first documented human right mammary artery to right coronary artery (RCA) bypass done by Goetz in 1960; and the first successful human left internal mammary artery (LIMA) to left anterior descending (LAD) artery sutured anastomosis was performed by Dr. Kolesov in 1964. However, after the first CABG using cardiopulmonary bypass (CPB) was performed by Dubost and colleagues , the development and popularization of techniques of extracorporeal circulation and electromechanical cardioplegic arrest led to the abandonment of beating heart surgery during the 1960s and 1970s .

The pioneering efforts of Dr. Buffolo from Brazil and Dr. Benetti from Argentina demonstrated the feasibility of performing coronary artery revascularization without the use of CPB and stimulated the resurgence of OPCAB in the early 1980s. From then on, continued technical variations and implementation of different surgical techniques and approaches improved the safety of OPCAB procedures. Benetti demonstrated that temporary occlusion of a coronary artery does not harm significantly the cardiac muscle and used silicon snares to interrupt blood flow to facilitate graft anastomoses. Simultaneously, Rivetti and Gandra began studying in 1983 the use of intraluminal shunts in beating heart surgery. A technique to expose the lateral and inferior walls by means of four slings without stabilizing device was described by Calafiore et al. Video 16.1 .

A novel maneuvers such as the “Lima suture,” described by Ricardo Lima from Brazil, permitted exposure of coronary arteries in the circumflex territory, thereby allowing for complete revascularizations with less hemodynamic instability .

Video-assisted techniques in the 1990s endorsed the foundation of mini invasive cardiac surgery, also known as minimally invasive direct coronary artery bypass (MIDCAB), and left anterior small thoracotomy (LAST) operation. In 1994 Benetti performed the first CABG off-pump through a small left anterior thoracotomy using video-thoracoscopy to dissect the LIMA without opening the pleural cavity. With this successful experience, Benetti was the first to have found the principles of minimally invasive cardiac surgery: small incision, LIMA as the ideal conduit, no CPB use, no aortic manipulation, and no invasion of the pleural cavity . A series of 155 patients with isolated LAD lesions that underwent the LAST operation was reported by Calafiore , and the MIDCAB technique was later standardized and published by Subramanian . Following the development of MIDCAB, Benetti further developed, in 1997, the MINIOPCAB approach, in which off-pump CABG was performed through a subxiphoid incision, using 3D video endoscopy to assist in the operation .

In addition to the innovative surgical approaches proposed, Dr. Benetti collaborated with industry to develop technologies for off-pump CABG surgery. The first MIDCAB and median sternotomy retractors, mechanical stabilizers, suction devices, and suction positioners were developed by the industry for large-scale use . The blower–mister, a humidified air blower device developed by Dr. Tomas, enabled a bloodless field . These technological developments allowed surgeons to perform OPCAB procedures under conditions similar to those of conventional CABG surgery. OPCAB gained popularity at the time and expanded worldwide across 45 countries , making possible that 46% of Asian, 20% of American, and 15% of European CABG surgeries were performed without CPB by the year 2000 .

The 1990s technological advancements and their applications in cardiac surgery boosted the introduction of the robotic approach for minimally invasive CABG surgery. In 1998 the first totally endoscopic coronary artery bypass (TECAB) grafting was performed by Loulmet and colleagues in France. Thereafter, during the last 20 years, robotic techniques have evolved from single graft placement to multivessel endoscopic bypass surgery, and from single LIMA harvesting to bilateral IMAs harvesting . Several authors have reported their outcomes in robotic-assisted CABG procedures, such as off-pump TECAB (graft harvesting and anastomosis with a closed chest), on-pump TECAB and robotic off-pump MIDCAB (robotic-assisted left IMA harvesting and manual anastomosis through a mini-thoracotomy), showing relatively safe perioperative outcomes and comparable results with conventional CABG . Furthermore, historical operating systems such as the automated endoscopic system for optical positioning and the Zeus robotic surgical system have evolved to the current da Vinci surgical system (Intuitive Surgical, Inc., Sunnyvale, California, United States), and specific robotic instruments have been developed for coronary bypass surgery .

The most challenging maneuver reported by surgeons during off-pump TECAB operation is suturing of the distal anastomoses. However, recent technological advances now permit this procedure to be done with robotic endoscopic sutures or with the help of U-clips (Medtronic, Minneapolis, Minnesota, United States) or anastomotic devices such as the automated C-Port xA Distal Anastomosis System (Cardica, Inc., California, United States) . Current limitations of robotic approaches include high cost, limited training opportunities and complex learning curve, evolving instrumentation and techniques accounting for differences between studies, lack of studies that can be extrapolated to the general population, and lack of routine angiographic follow-ups to demonstrate technical efficacy. Robotic techniques are described in details elsewhere in this book.

The evolution of the last operation (minimally invasive direct coronary artery bypass grafting, MIDCABG)

The LAST operation was successfully introduced during a period of strong weakness of percutaneous coronary intervention . Stenting had a mediocre outcome and balloon angioplasty was more or less abandoned. The introduction and early success of the LAST operation initiated a widespread interest in myocardial revascularization on a beating heart. This strategy found enthusiastic approval from the scientific world, even in the absence of a strong and demonstrable scientific background.

The improvement in stent technology with the introduction of the drug eluting stents at the starting of the new millennium brought any isolated LAD coronary artery lesion again into the domain of the interventional cardiologists. The LAST operation became less and less appealing, being a technically difficult procedure. Furthermore, the case load was not enough to guarantee a reasonable learning curve except in experienced hands.

The LAST operation adapted to the new environment and evolved in three new directions:

• 1.
  

  Complete myocardial revascularization via LAST. An incision more or less like the LAST is used to harvest both internal thoracic arteries ( Fig. 16.1 ), which are used in a Y configuration for revascularization of the anterior and lateral wall of the heart. The results are outstanding in expert hands. Nambiar et al. reported 819 patients with 3.1 graft/patient, 79% of whom extubated in the operating theatre. Early mortality was 0.7% and 12-month patency rate 99.5%.

  
  

  
  

  
  

  

  
  

  
  

  The right pleura is opened and the right lung gently retracted by means of sponges or dedicated retractors. The right internal thoracic artery is dissected as a skeletonized conduit under direct vision.

  
  

  Source: From Kikuchi K, Chen X, Mori M, Kurata A, Tao L. Perioperative outcomes of off-pump minimally invasive coronary artery bypass grafting with bilateral internal thoracic arteries under direct vision. Interact. Cardiov. Th. 2017;24(5):696–701. https://doi.org/10.1093/icvts/ivw431 .

  
  
  
  
• 2.
  

  Complete myocardial revascularization via a larger left thoracotomy. This approach allows to harvest both internal thoracic arteries (ITAs) and to use additional graft conduits, like radial artery or saphenous vein grafts. Srivastava et al. pioneered this strategy, but Guida et al. reported the widest series so far published with 2528 patients, an operative mortality of 1%, 97.3% of the patients extubated in the operating theatre and a 10-year survival of 69.1%.

  
  
• 3.
  

  Hybrid revascularization. The aim of hybrid coronary revascularization (HCR) is to mix the best revascularization possible for the LAD artery (left ITA) with stenting of the other coronary vessels. Proposed in 1996 by Angelini et al. , HCR found a renewed interest during the last decade. In a recent metaanalysis Harskamp et al. , comparing patients who underwent HCR or CABG, found similar 3-year outcome, but higher revascularization rate in the HCR group. A randomized study by Tajstra et al. reported similar 5-year outcome in patients undergoing HCR or CABG. However, randomized trials are needed to confirm the safety and effectiveness of this novel approach .

There is no doubt that the most appealing direction of the LAST operation is complete revascularization using a small as possible left thoracotomy.

This requires a considerable learning curve particularly to achieve complete arterial revascularization. If this goal is not obtained, the LAST procedure cannot be considered a valid alternative to conventional median sternotomy surgical revascularization .

Off-pump coronary artery bypass via sternotomy: Stabilization techniques

OPCAB procedures can now be accomplished with the help of the newly manufactured stabilization devices from diverse companies. There are several tissue stabilizers in the market offering increased workspace by low profile arms ( Fig. 16.2 ) with enhanced stability, flexibility, and range of motion, as well as malleable and movable pods ( Fig. 16.3 ) to allow better visualization . Furthermore, heart positioners ( Fig. 16.4 ) have evolved and provide cardiac tissue capture through gentle vacuum compression on the apex, enabling elevation of the heart for inferior face exposure with conserved hemodynamics ( Fig. 16.5 ).

Current tissue stabilizer.

Source: Used with permission from Medtronic.

Types of pods.

Source: Used with permission from Medtronic.

Heart positioners, Medtronic Starfish.

Source: Used with permission from Medtronic.

Exposure of inferior wall of left ventricle.

In OPCAB surgery, depending of the characteristics of the heart, the exposure of the anterior vessels can be done with traction of the pericardial deep stitch ( Fig. 16.6 ) ( Video 16.2 , Courtesy of Glineur, Etienne, Papadatos, Cliniques St Luc Bouge, Belgium) toward the patient’s feet and to the left, and with the right pericardial sutures relaxed or the use of the LIMA stiches ( Video 16.3 Courtesy of Glineur, Etienne, Papadatos, Cliniques St Luc Bouge, Belgium) . For anterolateral targets (diagonal branches) the cardiac positioner can be placed in the apex and directed toward the surgeon’s right shoulder or patients right leg; it is important that heart displacement is gradual and followed each time by a period of stabilization and monitoring of the hemodynamics ( Video 16.4 , Courtesy of Glineur, Etienne, Papadatos, Cliniques St Luc Bouge, Belgium). Abrupt changes in positioning often results in need to emergently convert to on-pump procedure.

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