When one or more of these arteries develop any blockage or narrowing the blood supply to the heart muscle is reduced. We reinstitute blood supply by bypassing block with another artery or vein which is connected before and after the blockage. This is normally done by stopping the heart by connecting it to heart-lung machine. Heart- Lung machine is a sophisticated device which incorporates artificial lung as a part of its circuit. The total blood volume of the patient is circulated through this machine which generates can generate some side effects namely inflammation, anaemia, coaulation defects, bleeding, strokes etc. The bypass surgery that is performed without the aid of the Heart-Lung machine is known is Beating heart bypass surgery.

It has been postulated that beating heart bypass surgery should reduce the incidence of side effects which are caused by heart lung machine. However, this is yet to be proven in randomised controlled trials.

Beating heart bypass surgery is carried out by stabilizing the segment of heart that is bypassed with an aid of special tissue stabilizer. Heart continues to beat as normal during this whole procedure. Temporary shunting device is used during this surgery to minimize blood loss and maintain circulation in the arteries of heart. Additional training and experience is required to carry out bypass surgery on beating heart. Some studies have shown reduced incidence of stroke, bleeding and atrial fibrillation(spelling or irregular heart beat) with this technique.