How does cardiovascular disease develop? What are some effects of cardiovascular disease? How is cardiovascular disease treated?
Cardiovascular disease (CVD) is the term used to describe atherosclerosis, or hardening of the arteries, as it affects the heart. It is an expression of progressive damage to (or some think natural aging of) the blood vessels that nourish the heart. These blood vessels, or coronary arteries, start off, as do all arteries, with a smooth inner lining. Over time, material becomes imbedded in plaques, or deposits, under the inner lining. This material is a mixture of cholesterol, fatty acids, and scar tissue; ongoing inflammation is an active part of this process.
Cardiovascular disease develops at widely differing rates in different individuals based on a variety of factors. High blood pressure, abnormal blood cholesterol levels (high LDL "bad" cholesterol and/or low HDL "good" cholesterol), smoking, diabetes, male gender, and hereditary factors all independently increase the risk of CVD developing earlier and earlier in life. Other risk factors include high levels of saturated fat and cholesterol intake (whether the blood cholesterol levels are abnormal or not), being overweight, being sedentary, the use of cocaine, and perhaps high levels of other chemicals in the blood, like homocysteine. Each of these factors cause damage to the arterial lining and/or cause plaques to develop more rapidly.
There are direct and indirect effects of CVD. Direct effects include angina pectoris, unstable angina, and myocardial infarction (MI) - a heart attack. Indirect effects include irregular heart rhythms, cardiac arrest, and congestive heart failure.
Angina pectoris results when plaques narrow the diameter of coronary arteries to the extent - usually by 70 percent or more - that the heart becomes significantly deprived of blood during times of exertion. This typically causes chest pressure or pain, though people may experience any of a variety of symptoms, including a sensation of indigestion; dizziness; breathing difficulty; sweatiness; nausea; or pain, pressure, or numbness in the neck, jaw, or arms. Stopping the exertion and placing nitroglycerine under the tongue helps restore the blood flow balance in this situation and the symptoms usually resolve in 5 to10 minutes. This pattern of symptoms is called stable angina.
If the degree of coronary artery blockage becomes extreme, symptoms may be brought on by lower and lower levels of exertion, or symptoms may be stronger, last longer, or take more time to resolve. When this progression happens rapidly or when a person experiences symptoms at rest, it is called unstable angina.
Those with unstable angina are at very high risk for MI (heart attack) in the very near future. A heart attack results when there is total or nearly total blockage of a coronary artery. Each minute the blood vessel stays blocked, more and more heart muscle will permanently die. Some people experience a gradual progression from stable to unstable angina, but about half the time, unstable angina or a heart attack will occur in someone with no preceding angina. This is caused by plaque rupturing with the sudden development of a blood clot over the plaque.
The indirect effects of cardiovascular disease stem from changes in the heart muscle as a result of sudden decreased blood flow, which leads to cardiac arrest and some irregular heart rhythms, or gradually decreased flow, which can cause congestive heart failure and other irregular heart rhythms.
Treatment for CVD includes lifestyle modification, medications, and procedures aimed at minimizing plaque formation and helping maintain blood flow balance to the heart. For those with unstable angina or heart attack, the treatment goal is rapid restoration of coronary artery blood flow. Quitting smoking and drug use, eating a diet low in cholesterol and saturated fat, exercising regularly, maintaining a lean body weight, and controlling diabetes, high blood pressure, and abnormal blood cholesterol levels with lifestyle changes and medications (there are many) all help reduce the effects of CVD.
Medications used for stable angina itself include nitroglycerine (short- and long-acting), beta blockers, and calcium channel blockers, all of which help to balance the heart's supply and demand for blood. Aspirin is helpful in reducing the chance of clot formation, and it and several other medications may help by reducing inflammation within the plaques.
Unstable angina requires aspirin and beta blockers and stronger blood thinners (heparin) while preparations are being made to look directly at the coronary arteries with an angiogram. Based on the location of any blockage(s) found on the angiogram, angioplasty or bypass surgery may be performed. Angioplasty can be done along with the angiogram and involves passing a small balloon across the blockage and inflating it; most of the time the blockage will then stay open. In addition, a small wire-mesh tube, called a stent, may be left behind within the blockage to minimize the chance of it reclosing. Angioplasty, angioplasty with stenting, or bypass surgery may also be performed electively for people with stable angina.
When a patient is in the throes of a heart attack, time is of the essence. The strongest blood thinners available - thrombolytics like TPA and related medications - those that will rapidly dissolve a blood clot, are utilized. Other helpful medications include aspirin, beta blockers, heparin and ACE inhibitors. Angioplasty and stenting may be used instead of thrombolytics or if thrombolytics fail. Bypass surgery may be performed in certain situations as well.