Coronary artery bypass surgery or coronary artery bypass grafting (CABG) or commonly known as the "bypass surgery" is one of the principle therapies to prolong survival and improve the quality of life of patients suffering from coronary artery disease (CAD). Coronary artery disease (CAD) is narrowing or blockage of one or more of the coronary arteries that supply oxygen-rich blood to the heart causing chest pain or heaviness due to myocardial ischemia or infarction.
Coronary artery bypass surgery restores normal blood flow to the heart by creating a “detour” (bypass) around the blocked artery/arteries. This is done by using a healthy blood vessel, called a graft. Grafts are usually obtained from other arteries and veins located in the chest, leg or arm. Creation of this additional passage of blood flow from the graft provides a new pathway to carry oxygen-rich blood to the heart, restoring the blood supply to the ischemic myocardium, thereby causing relief of symptoms.
The surgery usually begins with induction of general anesthesia following which the surgeons harvest blood vessels for grafting from the leg, chest or the arm. Access is gained to the heart either using midline incision and median sternotomy for multiple grafts or via chest incision and thoracotomy for isolated left side grafts.
In on-pump CABG the pumping action of the heart is taken over by the heart lung machine and the beating of the heart is stopped by the use of cardioplegia. Circulation of blood in the body and oxygenation of blood during the period of grafting is then taken over by the heart lung machine. While the heart is stopped the surgeon performs the graft procedure by sewing one end of a section of a blood vessel over a tiny opening made in the aorta and the other end over a tiny opening made in the blocked coronary vessel, distal to its blockage. Once the grafting complete, the heart is restarted and once satisfactory contractile function of heart is returned, the cardiopulmonary bypass is weaned off.
Off Pump CABG grafting or Beating-heart bypass is usually done without stopping the pumping function of the heart and without using a heart-lung bypass (CPB) machine. During the process of grafting, the heart is steadied with a mechanical device called octopus/starfish. Off Pump CABG is technically more difficult for surgeons because the heart is beating, and surgeons do not have easy access to blood vessels and requires the surgeon to have extremely high level of skill, training and understanding. This form of CABG mayhowere be safer and preferably performed for subset of patients, with high anticipated risk of complications from use a heart-lung bypass machine. These include older adults and people who have severe ventricular dysfunction, poorly controlled diabetes, long standing kidney disease, and chronic lung disease.
Minimally invasive direct coronary artery bypass or MIDCAB) is a modified version of CABG where the chest bone is not cut open. Instead, the surgeon makes a smaller cut on the left side of the chest over the artery that needs to be bypassed and enters in between the ribs. This procedure is also usually an off-pump beating heart procedure and is used where isolated left sided vessels are involved.
Once the revascularization is complete, the patient is shifted to ICU for further optimization of the heart and lung function, control of blood pressure and monitoring for post operative complications like bleeding, low cardiac output, renal dysfunction, stroke, gastrointestinal dysfunction. All measures are taken to ensure complete asepsis and prevent infection in the post operative period. After ensuring complete recovery and stability in the ICU over 24-48 hours, patient is usually shifted to room for further rehabilitation, strength building, physiotherapy, nutritional build up and return to normal physiological state.
