Coronary artery bypass grafting (CABG) is a treatment for coronary heart disease. Until recently, veins have been harvested through a long incision. However, a radical new technique has changed that, leading to improved patient outcomes.
Coronary artery bypass grafting (CABG) is one of the most effective and frequently performed operations in the world today. An estimated 23,000 cases are performed each year in the UK and 800,000 per year worldwide, including over 1,100 per year at Royal Brompton and Harefield Hospitals.
This operation involves creating a ‘new’ pathway for blood to flow through called a ‘graft’; it lets blood flow around the narrowed part of an artery. A bypass graft will allow more blood to reach the part of your heart muscle where there was a reduced supply before.
Some patients may only need a single graft although, more commonly, two, three or four grafts are needed. These grafts require an autologous conduit; the most frequently used and arguably the best are the internal mammary artery from the chest, and the saphenous vein retrieved from the leg at the time of the heart surgery. All these veins and arteries can be removed without any damaging effect on blood circulation.
Often in order to harvest veins from the legs, long incisions of up to one metre would be made in the leg. This method is associated with leg and sternal wound infection and delayed walking, which usually leads to longer hospital stays. These more traditional methods of vein harvest, in which this wound is opened along the length of the long saphenous vein, can often contribute significantly towards higher patient morbidity.
Minimally invasive vein harvesting
It was proposed that smaller incisions would minimise these problems, driving the development of endoscopic vein harvesting (EVH), which is now a frequently used technique at Royal Brompton & Harefield Hospitals.
The advent of the EVH method has allowed our surgeons to minimise infection. Many studies have demonstrated significantly reduced pain, lower infection rates and shorter hospital stays.
One Harefield Hospital patient (who was treated in 2010) had EVH on one leg, and the open technique with a previous CABG on the other, and testified to this saying:
“[There is] no comparison. On the left leg where they took the vein from thigh to foot it took 10 weeks to heal. It was always sore and inflamed. With the scope (EVH) it’s already healed [by day four]. Never even noticed it. No pain, no discomfort. It’s as if it never happened.”
While saphenous veins harvested endoscopically have been shown to have histologically similar appearances compared to those harvested by the open method, preliminary studies looking at endothelial changes at the cellular level have given a mixed opinion.
Early studies showed statistically non-significant differences in graft patency at 6-months and similar rates of event-free survival at 5 years. The technique has not, however, been put through a rigorous prospective randomised trial to demonstrate its efficacy on long-term graft patency or patient outcomes. This reflects the ethical and logistic dilemmas of repeat angiography for large cohorts of asymptomatic patients. Also currently absent from the literature is a large multi-centre trial focussing on patient reported outcomes.
However, the data compiled over the 7 years of this procedure performed at Harefield Hospital confirms the short- and mid-term safety and efficacy of EVH.
How is the procedure carried out?
The endoscopic vein harvesting (EVH) procedure is carried out with the patient under general anaesthesia, at the same time they are undergoing the coronary artery bypass graft (CABG). An endoscope is introduced via a small 1cm incision near the knee, to visualise the subcutaneous plane in which the long saphenous vein lies.
The vein is mobilised using a transparent dissector and the vein branches cut and separated away from the vein. The subcutaneous tunnel is drained with a small drain to avoid haematoma. The vein extracted is then used as a graft in the CABG surgery.
Truly a minimally invasive technique, the one metre incision is reduced to a one to two centimetre incision. This has resulted in reduced pain, lower chance of leg and sternal wound infection, earlier mobilisation and a shorter length of stay on average compared to the open method.
Expert treatment at Harefield Hospital
Mr Toufan Bahrami, consultant in cardiac surgery, was the first surgeon using this technique on a regular basis in the UK, having introduced this technique in 2007 following a 30-case trial.
He has trained surgical assistants and consultants from across the world over the last seven years and from this work many units in the UK have been able to launch their own EVH programmes.
Harefield Hospital has performed the largest number of cases in Europe and has over 7 years of follow up data available. This data supports that the EVH technique provides the same mid and long term outcomes as the larger incision open method.
The Harefield Hospital results have been published and presented in national and international meetings, including at the European Society of Cardiothoracic Surgery. An internal audit at the hospital indicated that the rate of infection using the EVH method was significantly reduced to only 2 per cent compared to up to 20 per cent.
This technique is now supported by the National Institute for Health and Clinical Excellence (NICE).