Indications for Coronary angiography
A coronary angiogram is a special form of x-ray that allows the diagnosis of blockages or narrowing of the vessels that feed oxygenated blood to the heart. Sometimes severe narrowing of these vessels with plaque (cholesterol and other particles) can cause chest pain or angina. Angina that comes when one is not exerting oneself is often more concerning then angina that is felt when one is involved in strenuous activity. Often times, angina at rest may be an indication of vessel that is blocked. When the heart muscles don’t receive the oxygenated blood they needed to function, they start to die. This is called a heart attack or myocardial infarction (MI). On the other hand, exertional angina that is stable over time and does not increase, may be an indication of artery narrowing, that causes ischemia, a condition where the heart muscles don’t get enough oxygenated blood.
What is Angiography
During a angiography, a tube, or catheter, is inserted into an artery in the groin (the Femoral artery). A special radio-opaque dye is injected down the tube and x-ray pictures are taken as the solution passes through the blood vessels. If there is narrowing or blockage of these vessels, it will often be clearly shown as the dye will suddenly appear narrowed or not appear at all in certain segments of the coronary arteries.
Indications for Angiography
- persistent angina pectoris:
* Character: More often described as a discomfort, pressure, or squeezing sensation. Less commonly as burning, sticking, or sharp.
* Location: Most often in the substernal area, precardium, or epigastrium with radiation to the left arm, jaw, or neck. Less commonly felt only in radiation areas and not in the chest.
*Precipitation: Often provoked by exertion, emotion, exposure to cold, eating (4 “E”s), or smoking, and relieved by rest, removal of provoking factors, or sublingual nitrates.
* Duration: Usually lasts a few minutes, rarely over 20-30 minutes.
* The frequency and severity of the symptoms change little with daily activities, and pain does not usually occur at rest.
- angina pectoris with markedly positive stress test
* definition of positive stress test
* positive stress test on stage 1 on treadmill
* more than 2mmST depression on exercise electrocardiography
* persistent ST depression throughout 5 minutes of recovery
* exercise induced hypotension
* inappropriate heart rate response to exercise (chronotropic incompetence)
- unstable angina pectoris: usually presents in one of three patterns:
- angina pectoris of recent onset (less than 1 month) that is provoked by minimal exertion.
- chronic stable angina showing a crescendo pattern, with chest pain occurring more frequently, with greater severity and duration, with less provocation, and requiring larger doses of nitroglycerine to abort attacks.
- prolonged chest pain at rest, clinically indistinguishable from acute MI at the time of presentation.
- positive stress test following myocardial infarction
- Young patients: if there is a strong family history of coronary artery disease or early death with or without risk factors
- Variants of Angina Pectoris: such a Prinzmental variant, and those that have small vessel disease
- Preoperative evaluation of valvular heart disease
- Left ventricular aneurysm: indicated by abnormal chest x-ray, persistent ST elevation on ECG
- postoperative coronary bypass surgery: indicated if patients have recurrent angina pectoris; in general, if angina pectoris occurs one year after bypass surgery, occlusion of the grafts should be suspected
- Resuscitation from sudden cardiac death: Advanced coronary disease is found in people who are resuscitated from cardiac arrest because these survivors of ventricular fibrillation usually have acute transmural infarction
Angioplasty is a procedure when a balloon is passed into a coronary artery at the end of a catheter (tube) and is then inflated to open a narrow or blocked artery. There are two techniques for performing angioplasty: transmural and subintimal. In the transmural technique the balloon is placed within the layers of the center of the artery (the lumen), where blood would normally flow. In subintimal angioplasty, the balloon is placed within the layers of the arterial wall. The artery opening is enlarged as the plaque is compressed and redistributed against the arterial wall.
A stent is a steel-like metal wire mesh scaffold that is used to prop open a clogged blood vessel. Stents are often used in conjunction with balloons to prevent closure or restenosis of the coronary arteries on a more permanent basis. There two different types of stents used currently: bare metal and drug eluting stent. Bare metal or non medicated stents are cheaper, but carry the risk of restenosis and plaque buildup after a period of time. Medicated stents have the same base as non-medicated stent, plus a uniform coat of a drug that is released over 30-120 days to prevent restenosis.
Indications for stent placement:
- minimum diameter of stenosis of <10%
- there should be final TIMI low grade 3, without occlusion of a significant side branch, flow-limiting dissection, distal embolization, or angiographic thrombus
- Settings in which direct stenting might be considered include:
- Vessel ≥2.5 mm in diameter
- Proximal lesion location
- Absence of severe coronary calcification
- Absence of significant angulation (bend >45º)
- Absence of very severe lesions and bifurcation lesions