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What causes heart (cardiovascular) disease?
Heart or cardiovascular disease is the leading cause of death in the United States and often can be attributed to the lifestyle factors that increase the risk of atherosclerosis or narrowing of arteries. Smoking, along with poorly controlled hypertension (high blood pressure), and diabetes, causes inflammation and irritation of the inner lining of the coronary arteries. Over time, cholesterol in the bloodstream can collect in the inflamed areas and begin the formation of a plaque. This plaque can grow and as it does, the diameter of the artery narrows. If the artery narrows by 40% to 50%, blood flow is decreased enough to potentially cause the symptoms of angina.
In some circumstances, the plaque can rupture or break open, leading to the formation of a blood clot in the coronary artery. This clot can completely occlude or block the artery. This prevents oxygen-rich blood from being delivered to the heart muscle beyond that blockage and that part of the heart muscle begins to die. This is a myocardial infarction or heart attack. If the situation is not recognized and treated quickly, the affected part of the muscle cannot be revived. It dies and is replaced by scar tissue. Long term, this scar tissue decreases the heart's ability to pump effectively and efficiently and may lead to ischemic cardiomyopathy (ischemic=decreased blood supply + cardio=heart + myo=muscle + pathy=disease).
Heart muscle that lacks adequate blood supply also becomes irritable and may not conduct electrical impulses normally. This can lead to abnormal electrical heart rhythms including ventricular tachycardia and ventricular fibrillation. These are the heart arrhythmias associated with sudden cardiac death.