|The optical coherence tomography machine at Apollo hospital
A machine that can give a clearer and more detailed image of a coronary artery was installed at a city hospital on Saturday.
“The OCT (optical coherence tomography) image can clearly define the exact character of a blockage inside an artery. Based on the imaging, the decision on the kind of angioplasty required for a patient can be taken,” said cardiologist Rabin Chakraborty, the director of Apollo Gleneagles Heart Institutes.
The machine, which costs more than Rs 1 crore, was installed at Apollo Gleneagles Hospitals off EM Bypass.
The OCT, an imaging technology based on infrared light, enhances accuracy during an angioplasty. During a coronary angiogram, a fibre-optic catheter of 1.2mm diameter is inserted through the groin. Through the catheter, a .3mm wire fitted with infrared light goes inside the artery and creates a three-dimensional image that defines the character of an arterial block.
Doctors said there could be several reasons for the formation of a coronary blockage such as excess calcium deposit in the artery.
In case of a fibrotic blockage, the tissues harden and block the artery.
A thrombotic blockage occurs when abnormal layers of fat and muscle cells or plaques deposit on the artery walls. “The surface of the plaques are rough compared to a normal arterial wall and so blood tends to clot and it can cause an artery to get blocked completely,” said a cardiologist.
The image produced by the OCT helps cardiologists take the decision on what type of angioplasty would help.
“In case of a calcium blockage, the balloon used for angioplasty must have sharp blades to cut through the hard deposits. Also, after the angioplasty is done, pictures can be taken again to find out the result of the procedure… whether the blockage has been completely removed or not. At the same time, the extent of the diseased artery can be gauged,” said Chakraborty.
To clear a thrombotic blockage, the thrombus has to be sucked out by using a suction catheter and inject anti-thrombotic drug.
For a coronary angiogram until now, the diameter of the catheter is normally 3mm and so it can only reach the mouth of the artery and not go inside, Chakraborty said.
“It injects a dye inside the artery and produce an image but doesn’t give the precision image of the artery wall and character of the blockage,” Chakraborty said. “If an imaging technique like OCT helps precise diagnosis of the problem, it’s easier to select patients who actually need intervention,” said cardio-thoracic surgeon Kunal Sarkar.