Contributed By Assoc Prof Naik Madhava Janardhan, Senior Consultant, Cardiothoracic Surgery and Dr Marco Lizwan, Medical Officer, Cardiothoracic Surgery

Coronary Artery Bypass Graft (CABG) emerged in the mid-20th century and has since become one of the most rigorously studied surgical procedures.

Its technical complexity and delicate tissue handling required have driven continuous refinement. This scrutiny has also made CABG one of the safest surgical procedures available. Off-pump coronary artery bypass (OPCAB) is a specialised technique that evolved from traditional CABG. It was designed to reduce complications associated with the use of the heart-lung machine, also known as cardiopulmonary bypass or "the pump".

The Traditional CABG

Fig 1. When the heart is stopped during conventional CABG, the bypass machine performs the heart's function by circulating blood throughout the body.

Whilst CABG ironically began as an off-pump operation, the invention and widespread adoption of the heart-lung machine revolutionised cardiac surgery, making operations technically easier and more accessible through its safe use in all heart procedures. This approach involves connecting the heart to a machine using multiple cannulae or tubes, which allows the pump to take over the heart's function. The use of the pump makes it possible for the heart to be stopped during the procedure, allowing surgeons to operate on a motionless and relatively bloodless field. As part of the relentless quest to improve outcomes, the adverse effects of this artificial circulation were studied and certain drawbacks were found such as increased risk of stroke, cognitive impairment, injuries to organs like the kidneys and increased blood transfusion requirements. These findings led to refining off-pump techniques as an alternative for patients who might be at higher risk for these pump-related complications.

Beating Heart Surgery

OPCAB, also called "beating heart surgery", re-emerged as a technique in the late 1990s. Early experience was challenging as surgery on a continuously moving heart presented inherent difficulties. This was compounded by disruptions to the heart's rhythm (arrhythmias), which resulted in sudden drop of blood pressure and other complications. Multiple stabilisation devices were designed and tested until the field reached the present suction-based stabilisation through devices imaginatively called the OCTOPUS (resembling an arm of the octopus) and positioners called the STARFISH or URCHIN (Fig. 2). The availability of these devices, along with certain ancillary devices such as the Blower-Mister (which provides a bloodless field) and the intra-arterial shunts (used to prevent the deleterious effects of stopping blood flow to parts being operated upon), has made OPCAB a viable option for people who require it.

Figure 2. Examples of stabilisation devices and positioners used in beating heart surgery, OCTOPUS, STARFISH and URCHIN (from left to right).

Is Off-Pump Safe?

Most of the complications historically associated with OPCAB occurred during its early adoption phase. With increasing surgical experience and improved instruments, outcomes have improved significantly. The introduction of intraoperative assessment tools such as MEDISTIM (ultrasound-based transit flow measurement) and indocyanine green near-infrared fluorescence (NIRF) angiography further enhanced graft quality and patency assurance.

Globally, OPCAB now accounts for approximately 15-20% of all CABG procedures, with much higher adoption rates in Asia. In India and China, OPCAB constitutes more than 60% of CABG operations due to surgeon expertise and patient profile suitability (Fig 3). Current evidence shows that in appropriately selected patients, OPCAB achieves comparable graft patency, mortality and morbidity rates to traditional on-pump CABG.

Patient selection and surgical expertise are paramount – OPCAB is not inferior to on-pump CABG when performed by experienced surgeons. The choice of technique is guided by patient factors, including comorbidities, coronary anatomy and overall operative risk, rather than by rigid adherence to one approach.

Who benefits from Off-Pump?

The gold standard of coronary artery bypass grafting remains to be traditional on-pump CABG, one of the most studied and perfected surgeries worldwide. However, OPCAB offers distinct advantages in selected patients who would benefit from avoiding cardiopulmonary bypass.

This selective, patient-centred approach ensures that each individual receives the most appropriate surgical technique.

OPCAB is typically offered to:

• Patients with a heavily calcified ascending aorta ("porcelain aorta"), where aortic manipulation poses stroke risk
• Patients with renal dysfunction or high risk of renal injury
• Elderly or frail individuals and those with pre-existing cerebrovascular disease
• Patients with impaired ventricular function or anaemia, where minimising transfusion is desirable
• Patients requiring limited grafts with accessible target vessels

Future Directions and Innovations

Great inroads have been made in making surgical revascularisation of coronary arteries safer and more reliable. Cosmesis, which is more popular in excisional surgeries than in reconstructive surgeries, is now considered the next frontier in its evolution. The Minimally Invasive Direct Coronary Artery Bypass (MIDCAB) procedure is an exciting development in this journey. The not-so-popular "zipper" or the median sternotomy is replaced by a smaller lateral thoracotomy (going between the rib spaces without stretching or breaking them) which is becoming increasingly popular. The experience and expertise gained from OPCAB form the foundation for these procedures. Further advances are occurring independently, with Total Endoscopic Coronary Artery Bypass (TECAB) or even Robot Assisted CABG being performed in select centres.

Continuous refinement of surgical technique, intraoperative imaging and perioperative management ensures that patients can expect excellent long-term outcomes regardless of the chosen approach. The final decision between OPCAB and on-pump CABG is made through multidisciplinary team discussion, ensuring that each patient receives tailored, evidence-based care.

OPCAB is a mature and proven surgical technique that complements conventional CABG. With careful patient selection, adherence to surgical precision, and ongoing innovation, both techniques remain essential to the comprehensive management of coronary artery disease.

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