Coronary angiography is the gold standard test for direct visualization of the coronary arteries. It is an important diagnostic tool in the assessment of the blood supply to the heart and helps in deciding the treatment strategy for an individual patient which may include angioplasty and stent insertion or coronary artery bypass grafting (CABG).
What can this test show?
The heart lies within the chest wall cavity and is surrounded by the lungs, ribs, muscle, fat and skin. Therefore, the assessment of the coronary tree is not easy. Coronary angiography, utilizes X-rays emitted from a special camera to look inside the arteries of the heart. In addition, it can be utilized to quantify the pumping function of the heart and also measure pressures from the right and left sides of the heart.
What happens during the test?
The test is performed in the catheter lab. It usually takes 30 minutes but may take less or more than this. You will be starved for up to four hours before the procedure. Certain blood thinners such as warfarin are likely to be omitted a few days prior to the procedure. In the catheter lab, you will be asked to lie flat on a special table and a ‘C arm’ will move close to you. The X-rays emitter is below the table and you will not be able to see it while the receiver will be positioned above your chest.
You will be surrounded by a team of doctors, nurses, physiologists and radiographers who are working together as a team. During the test your heart rhythm and oxygen saturations will be continuously monitored.
Will I feel any pain?
You will be awake during the test. The initial aim is to gain access into a major artery for the catheter to be advanced to your heart. For your comfort, a local anaesthetic will be infiltrated into the skin to numb the access site. Following that, a needle is inserted into the artery and subsequently, the catheter is introduced. The procedure can be performed from your groin or wrist or less commonly, from your arm depending on the preference of the operating doctor (Figure 1). The catheter is a long plastic hollow tube which is less thick than a pencil. You will not feel the catheter as it advances towards the heart.
A special dye is injected to visualize the coronary arteries (Figures 2 and 3). This dye produces an excellent contour of the coronary tree and any blockage or narrowing within the arteries can be seen instantaneously. You may transiently feel a warm sensation, chest pain or flushing when the dye is injected but this is quite normal.
When the test is finished the catheter is taken out and a doctor or nurse will either put pressure on your groin or a special occlude device may be used to seal the tiny hole. Alternatively, if the procedure was performed through your wrist then a tight dressing may be applied there for some a few hours to prevent any bleeding.
Are there any risks involved?
Every procedure has a small risk attached to it. The important question is whether the benefits outweigh the risks or not. There is a 1-2% risk of bleeding, bruising, infection at the access site. Serious complications are rare but nonetheless there is a one in several hundred risk of an allergic reaction to the contrast, chest pain, stroke or damage to the artery at the access site. Finally, there is a 1 in 1000 risk of death but this is true for high-risk patients (previous heart attacks, stent insertion, heart failure, kidney failure or stroke) with poor health. You can ask for the complication rate of the operating cardiologist.
Dr Omar Rana performs this procedure at Omar Hospital & Cardiac Centre Lahore which is a heart attack centre and state-of-the-art hospital with advanced cardiac facilities.
Figure 1 Illustration of Coronary Angiography.
1=Catheter in the brachial artery in the arm, 2=Catheter in the femoral artery , 3=Heart.
Figure 2 The Left Coronary Artery as Seen During Coronary Angiography.
Figure 3 The Right Coronary Artery as Seen During Coronary Angiography.