Heart and blood vessel disease, or cardiovascular disease, is a significant cause of organ damage and fatalities. There are a number of associated risk factors, including elevated levels of LDL cholesterol and high blood pressure. As such, some cardiovascular therapies are aimed at decreasing these risk factors to stave off disease. Diagnosis, therapy and proper care should be under the consultation of a healthcare professional.
Definition
LDL stands for low density lipoprotein and consists of cholesterol and protein. It is structured this way because cholesterol alone is not soluble in blood, in other words it does not dissolve. The body combines it with protein so it can dissolve in blood, according to "Harrison's Principles of Internal Medicine," by Anthony S. Fauci, M.D.
Blood pressure refers to the force applied to the blood vessel walls from the pumping of blood. It is measured as two numbers, systolic pressure over diastolic pressure. Normal blood pressure, for example is considered to be less than 120/80 according to the National Institutes of Health. Systolic pressure is measured as the heart is contracting and diastolic as the heart is relaxing.
Function
According to "Robbins & Cotran Pathologic Basis of Disease," by Dr. Vinay Kumar, LDL functions to deliver cholesterol from the liver to the tissues. While high cholesterol is associated with abnormal health conditions, a small amount of cholesterol is needed by the body. It functions in cellular communication, the synthesis of steroid hormones, such as testosterone and estrogen, and the stress hormone cortisol; and stabilizes cell membranes, which cover and protect the cell.
Blood pressure is similar in that too high or too low of a BP level is dangerous to the body as noted by "Harrison's Principles of Internal Medicine." Blood pressure is a surrogate measure of the amount of blood delivered to the organs, along with several other indicators.
Mechanism of Disease
According to "Pathologic Basis of Disease," LDL cholesterol tends to deposit cholesterol derived from the liver into the tissues, particularly the blood vessel walls. This causes them to narrow and harden. If narrow enough, vessels restrict can blood flow to the organs. In addition, LDL makes plaques that can rupture, causing a sudden clot to form in the vessel and block blood flow completely. In the heart this causes a heart attack, in the brain a stroke, and can cause damage to other organs as well.
In addition, "Pathologic Basis of Disease" notes that low blood pressure indicates that the organs may not be receiving enough blood and can cause them to shut down, as if in shock. High blood pressure over time causes the muscular layer in the vessel walls to thicken, to withstand the higher force. This narrows the vessels; it also causes the heart to grow larger, interfering with its function. Acutely, high blood pressure can rupture blood vessels, or cause the organs to become dysfunctional, a condition called malignant hypertension.
Diagnosis
LDL cholesterol is measured by means of a blood test, usually after a period of fasting from food, typically overnight, according to "Harrison's Principles of Internal Medicine."
Blood pressure is measured on consecutive occasions. High blood pressure is considered to be a systolic pressure of over 139 or diastolic of over 89, as noted by the NIH.
Non-Medical Treatment
Conservative measures to treat high blood pressure and high cholesterol are similar. They involve abstaining from tobacco, increasing exercise levels and following a proper diet, such as one that's high fiber, low fat, low cholesterol and low sodium according to "Harrison's Principles of Internal Medicine."
Medical Treatment
"Harrison's Principles of Internal Medicine" notes that for high LDL cholesterol, medical treatment involves the use of one or more of several possible classes of drugs. One of the most common are statins. These are drugs that interfere with an enzyme in the liver called HMG-CoA reductase, responsible for making cholesterol. As another example, bile-acid-binding resins bind to bile acids in the digestive tract. The liver then takes up more cholesterol from the body to make more bile acids.
Several classes of drugs are also available to treat high blood pressure. Diuretics cause the kidneys to dispose of more fluid, derived from the blood, through the urine. The lower blood volume decreases the pressure. ACE inhibitors stop the formation of a hormone that narrows the blood vessels. Beta blockers stop stress hormones such as adrenaline from increasing the rate and force of contraction of the heart.
References
- "Harrison's Principles of Internal Medicine"; Anthony S. Fauci et al; 17th Ed 2008
- "Robbins & Cotran Pathologic Basis of Disease"; Vinay Kumar et al; 8th Ed 2009
- National Institutes of Health; National Heart, Blood and Lung Institute; The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure
