Coronary artery disease occurs when the arteries that supply blood to your heart become narrowed or blocked by fatty, cholesterol-containing deposits called plaques in a condition called athersclerosis. The blockage reduces the amount of blood and oxygen reaching your heart which can damage your heart muscles.
Coronary artery disease often develops slowly over the course of many years, so it may go unnoticed until it triggers a major episode. Eventually, reduced blood flow can cause chest pain (angina), shortness of breath, or other symptoms. A complete blockage can cause a heart attack.
Studies suggest that coronary artery disease begins with damage or injury to the inner layer of a coronary artery, sometimes as early as childhood. The damage may be caused or made worse over time by various factors, including:
- High blood pressure
- High blood cholesterol
- Lack of exercise
- High, unrelieved stress
- Some forms of radiation therapy to the chest
If your coronary arteries narrow too much, they can't supply enough oxygenated blood to your heart, especially during times of high stress or physical exertion. As plaque continues to accumulate, you may develop some or all of the following heart disease symptoms:
Shortness of breath. When your heart cannot pump enough oxygenated blood to meet your body's needs, any exertion may trigger a sudden shortness of breath or extreme fatigue.
Chest pain (angina). Emotional or physical stress can trigger this symptom, experienced as pressure or tightness in your chest. In some people, especially women, this pain may be fleeting or sharp and noticed in the abdomen, back or arm. Typically, the sensation goes away soon after stopping the stressful activity.
Heart attack. Complete obstruction of a coronary artery generally triggers a heart attack. The classic signs of a heart attack include a crushing pressure in the chest and pain in your shoulder or arm, usually accompanied by sweating and shortness of breath. Women are more likely than men to experience less typical signs of heart attack, such as back or jaw pain and nausea. Keep in mind that a heart attack can also occur without any apparent symptoms.
Treatment for coronary artery disease usually starts with lifestyle changes including increasing exercise, losing weight, stopping smoking, eating a healthy diet, and reducing stress. In some cases, drugs or surgical procedures may be necessary.
Various drugs can be used to treat coronary artery disease, including:
Aspirin: A daily dose of aspirin (or another blood thinner) can reduce the tendency of your blood to clot, helping to prevent obstruction of your coronary arteries. Check with your doctor before starting to take aspirin, particularly if are taking another blood thinner or have a bleeding disorder.
Cholesterol-modifying medications: Certain drugs can lower the low-density lipoproteins (LDL) or “bad” cholesterol in your blood, thus reducing your body’s supply of the main substance that clogs coronary arteries. Your doctor can choose from a range of medications, including statins, fibrates, niacin and bile acid sequestrants.
Beta blockers: If you've had a heart attack, beta blockers can reduce the risk of future episodes. These drugs decrease your heart's demand for oxygen by slowing down your heart rate and lowering blood pressure.
Calcium channel blockers: These medications relax the muscles that surround your coronary arteries and cause the vessels to open, increasing blood flow to your heart. They also control high blood pressure.
Nitroglycerin: Nitroglycerin tablets, patches or sprays can control angina symptoms (chest pain) by temporarily expanding your coronary arteries and reducing your heart's demand for blood.
ACE inhibitors and ARBs: If you've had a heart attack, ACE (angiotensin-converting enzyme) inhibitors and ARBs (angiotensin receptor blockers) can reduce the risk of future attacks. These drugs lower blood pressure and help stem the progression of coronary artery disease.
Percutaneous Coronary Intervention (PCI)
PCI procedures, including angioplasty and stent placement, restore and improve blood flow to the heart muscle by opening blocked or narrowed arteries.
Your cardiologist uses a technique, called cardiac catheterization, where a long, thin tube (catheter)is inserted into an artery of your groin, wrist, or arm and snaked to the site of the arterial blockage or narrowing near your heart. A wire tipped with a deflated balloon is passed through the catheter to the site and then inflated and deflated to compress the plaque deposits against your artery walls and restore proper blood flow. At this point your doctor may choose to place a stent in the artery.
A tiny stainless steel mesh tube called a stent is mounted on a balloon and guided through the catheter to the plaque-filled site after angioplasty has reopened the artery. The balloon is inflated which expands the stent into the inner layer of the artery. A stent acts as a scaffold to hold the artery open, improving blood flow and relieving symptoms caused by a blockage. Some stents slowly release medication to help keep the artery open.
In most cases, a PCI procedure greatly increases blood flow through the previously narrowed or blocked coronary artery. Your angina symptoms (chest pain) should decrease, and you may have a better ability to exercise. Successful angioplasty can also eliminate the need for an invasive surgical procedure called a coronary artery bypass graft. However, angioplasty and stenting do not cure heart disease. You'll need to continue healthy lifestyle habits and may need medications to ensure that your artery doesn't re-narrow.
Angioplasty with stent placement is a less invasive way to open clogged arteries than open-heart bypass surgery, but the procedure still carries some risks. The most common include:
Bleeding: You may bleed at the site in your leg or arm where a catheter was inserted. This usually results in a simple bruise, but sometimes serious bleeding occurs that may require additional surgical procedures.
Re-narrowing of your artery (restenosis): With angioplasty alone — i.e., without stent placement — restenosis can happen in about a third of cases. Stents were developed to reduce restenosis. Bare-metal stents reduce the chance of restenosis to less than 20 percent, and drug-releasing stents reduce the risk to less than 10 percent.
Blood clots: Clots can form in stents after angioplasty; these clots can cause a heart attack. Certain medications can decrease the chance of clots.
The following complications of angioplasty are considerably less common:
Heart Bypass Surgery
When an artery supplying blood to the heart is severely blocked, a surgical procedure called a coronary artery bypass graft (CABG or “cabbage”) can reroute your blood around the blockage to restore the flow to your heart muscle. Your cardiac surgeon will use a healthy vessel from another part of your body to bypass the blocked or narrowed artery. The CABG procedure requires open heart surgery, so it is generally reserved for patients with more than one narrowed coronary artery.
After heart bypass surgery, most people feel better and often remain symptom-free for as long as 10-15 years. But although CABG improves blood supply to the heart, it is important to note that the procedure doesn't cure the underlying heart disease. Over time, other arteries, or even the new graft vessel used in the bypass, may become clogged. Your long-term outcome will depend on taking medications as directed and following healthy lifestyle recommendations. Your doctor may direct you to participate in a cardiac rehabilitation program of exercise and education.
Because CABG is major open heart surgery, you may have complications during or following your procedure. The most common are:
Less common complications include:
Infections of the chest wound
Memory loss or trouble thinking clearly (usually subsides within six to 12 months)
Heart attack, if a blood clot breaks loose soon after surgery
Your risk of developing these complications depends on your health before the surgery. Talk to your doctor to get a better idea of the likelihood of these risks.