What is Coronary Artery Disease?
Coronary Artery Disease (CAD) refers to the accumulation of cholesterol plaques in the arteries of the heart. The arteries serve as ‘pipes’ to supply blood to the heart muscles. These plaques would gradually result in the obstruction of blood flow in the arteries. When the narrowing is significant, symptoms such as chest pain or chest pressure could be experienced particularly during physical exertion or emotional distress, or when there is a mismatch of demand and supply.
When the plaques rupture or tear, blood clots would form around the plaque and result in sudden complete occlusion of the blood flow. This event is commonly known as a heart attack.
The approach to identifying CAD is multi-faceted. Some doctors rely on symptoms whilst others prefer to screen patients for the condition so that early treatment can be initiated. When a person experiences a heart attack, there is already a degree of damage to the heart muscles. The old adage of ‘prevention is better than cure’ holds true for the evaluation and treatment of CAD.
As an initial non-invasive test, most people will undergo a non-invasive test to detect CAD. These tests include the treadmill electrocardiography study, stress echocardiography and coronary CT angiography. The degree of accuracy to diagnose CAD is also in the same order. Although the mainstay of treatment is medication, those with significant CAD will be considered for invasive evaluation and therapy. The test known as cardiac catheterisation or coronary angiography is then offered.
What is the diagnostic process like?
In many cardiac centres in the world, including Singapore, the angiogram is carried out via an artery in the groin known as the femoral artery. A dye will then be injected through the catheter. The coronary arteries are identified under X-ray guidance. Areas of significant stenosis or ‘tight’ areas are then treated with balloon and stents. In some cases, after an angiogram, patients will be referred for coronary artery bypass.
Access through the femoral artery is usually simple, unless the patient is obese or has significant occlusion of the arteries supplying the lower limbs. This is the usual access route used for training doctors to perform this procedure.
In recent years, angiograms have also been carried out via the radial artery, an artery that lies just under the surface of our skin on our hand. Compared to the femoral artery, conducting angiograms via the radial artery is much safer with lower risks of bleeding. It also does not carry the risk of retroperitoneal (accumulation of blood) bleeding present in a high femoral artery puncture.
How has the advancement of diagnostic tests helped?
The technological advancement of medical equipment and techniques have allowed diagnostic cardiac catheterisation to become minimally invasive. The radial artery at the wrist has been identified and used frequently by experts familiar with this technique. Patients can regain mobility immediately after the diagnostic procedure and can be discharged three hours later. This is a major advantage over femoral access.
If intervention is required such as balloon or stenting, the same access at the wrist can immediately provide this treatment. Interventional cardiologists in Asia have led the way in the transradial approach for coronary intervention. Hopefully, patients who require cardiac evaluation will now be able to experience a less invasive approach to coronary cardiac care and seek treatment more comfortably.