According to the American Heart Association, more than 1 million Americans suffer a heart attack each year. For over 400,000 of them, death is the first symptom. There are four primary risk factors for heart disease: diabetes, cigarette smoking, high cholesterol and high blood pressure. All of them can be managed and most are preventable. Blood pressure is one of the leading causes of heart attacks because it is a "silent disease." You can have it for years before it's detected and by that time it may have already contributed to your first heart attack.
Anatomy of the Heart
Most people, even those with no medical training, are familiar with the function of the heart: it acts as a pump to supply blood to the body. It takes blood that has recently been "oxygenated" by the lungs and pumps it to muscles, the brain and other active tissues that depend on a constant supply of blood. What surprises many, however, is that the heart is dependent on its own, separate supply of blood that flows through the "coronary arteries." There are two major coronary arteries that supply blood to the heart: the right coronary artery (RCA) and the left main coronary artery, which branches into the circumflex artery and the left anterior descending artery. If any of the coronary arteries become obstructed, the body can create emergency, "collateral" arteries as a defensive mechanism to ward off a shortage of blood supply to the heart.
Atherosclerosis and the Narrowing of Arteries
Cholesterol begins to adhere to the inside walls of the arteries at a very early age through a disease process call "atherosclerosis." Even young adults in their 20s likely have the beginnings of atherosclerosis. As cholesterol continues to adhere to the inside walls of the arteries, the vessels narrow, allowing less room for blood to circulate. If this occurs in the lower extremities, it is called peripheral artery disease (PAD). If it occurs in the arteries that supply blood to the brain, it can lead to a stroke. If it occurs inside the coronary arteries, it can cause angina. Completely occluded coronary arteries often lead to a heart attack.
The Heart Attack
The first symptoms of a heart attack are chest pain, nausea, sweating, vomiting and severe pain down the left arm and side of the chest. While the heart can exist for years with a limited supply to the coronary arteries, eventually the demand may overshadow the supply and a heart attack will occur. In some cases, the coronary arteries can make "new" coronary arteries called "collateral arteries." Collateral arteries essentially bypass an obstruction and create new avenues for blood supply to the heart.
How High Blood Pressure Causes Heart Attacks
High blood pressure is one of four primary risk factors that contribute to heart disease. Over time, the high pressure of blood exerted against the inside of the coronary arteries damages the delicate lining. In response to the damage, the body attempts to heal the area by sending platelets to facilitate blood clotting. The more clotting that occurs, the narrower the internal diameter of the arteries, reducing blood flow to the heart. If there is sufficiently poor blood supply to the heart, a heart attack may occur.
High Blood Pressure and Atherosclerosis
If the atherosclerosis inside the coronary arteries has advanced, then high blood pressure can make a bad situation worse. Cholesterol that has lined the coronary arteries can become hard, brittle and may form cracks in the arterial lining. If this occurs, platelets will complicate the disease and may completely occlude the artery. Occasionally, the high pressure can result in pieces of plaque breaking off and travel "downstream" with the blood flow. If the piece of plaque is large enough or lodges in the coronary arteries in a critical area, it may result in a very rapid and complete occlusion of blood to the heart.
