Definition
High Blood Pressure (HBP) or hypertension is a persistent abnormal elevation of the pressure within the arteries which deliver blood to the entire body.
An adult’s blood pressure is calculated by using two numbers. The heart’s rhythmic pumping action creates the upper systolic pressure (normal is 120 mm. Hg. or lower) and its resting pressure between heart beats is the lower diastolic pressure (normal is 80 mm. Hg. or lower).
There are four stages of high blood pressure or hypertension:
STAGE 1 or Prehypertension is: 120/80 to 139/89 STAGE 2 or Mild Hypertension is: 140/90 to 159/99 STAGE 3 or Moderate Hypertension is: 160/100 to 179/109 STAGE 4 or Severe Hypertension is: 180/110 or higher
If your blood pressure is in the prehypertension range, it is likely that you will end up with high blood pressure unless you take action to prevent it. High blood pressure needs to be treated because it can lead to kidney failure, heart attacks, heart failure, stroke, and blindness.
Causes
In most cases, it’s impossible to pinpoint an exact cause of high blood pressure. There are, however, a number of factors that have been linked to high blood pressure including:
- A family history of high blood pressure
- Age - The incidence of high blood pressure rises in men after age 35 and in women after age 45.
- Gender - Men are more likely to have high blood pressure than women.
- Smoking – If you smoke cigarettes, you may have increased high blood pressure.
- Race - Approximately 33 percent of African-Americans have high blood pressure, compared to 25 percent of Caucasians.
Figure 1. Renal Artery Stenosis
Unfortunately, the cause of high blood pressure (hypertension) in 90% to 95% of the cases is unknown. The medical term for this kind of high blood pressure is primary or essential hypertension. Secondary hypertension has an identifiable cause.
One of the most important causes of secondary hypertension is the narrowing (stenosis) of arteries to the kidneys (renal arteries). Renal artery stenosis causes about 5% of all cases of hypertension and can reduce kidney size.
The kidneys are extremely sensitive to any decrease in blood flow. When renal artery stenosis restricts blood flow to even one kidney, it can lead to high blood pressure. When the stenosis involves both kidneys, it can also lead to impaired kidney function (renal failure). Stenosis of both renal arteries is a major cause of renal failure in the elderly.
There are two main causes of renal artery stenosis. In younger patients, thickening of the muscular wall of the artery, called fibromuscular dysplasia (FMD), is the usual cause. In older patients, narrowing from cholesterol-rich plaques in the artery (arteriosclerosis) is the most common cause.
Primary hypertension can not only damage the renal arteries, but also the kidneys. There is a direct relationship between uncontrolled high blood pressure and increased risk for stroke, heart attack, heart failure, renal failure and vision problems. The medical terms for this kind of renal failure, which can be caused by either primary or secondary hypertension, are chronic renal failure or end state renal disease (ESRD).
Warning Signs
High Blood Pressure (HBP) or hypertension is often referred to as the “silent killer” because there are no symptoms. Many people do not find out that they have high blood pressure until they have problems with their heart, kidney, or brain.
Secondary hypertension, which has an identifiable cause, is usually suspected in children, adolescents and young adults when there is an abrupt onset of high blood pressure. It also frequently occurs in patients whose high blood pressure is poorly controlled despite usual therapy, including medications. In these cases, renal artery stenosis can be detected by physical examination or special tests:
- A physician’s examination of the upper abdomen with a stethoscope may detect the abnormal sounds of turbulent blood flow through narrowed renal arteries.
- An Abdominal Ultrasound examination can detect abnormal blood flow to and within the kidneys.
- Magnetic Resonance Imaging (MRI) can display narrowed regions in the renal arteries.
- X-Ray Arteriography involves injection of a dye into the arterial system. It shows the location and extent of narrowing, which is necessary to determine whether the stenosis is severe enough to warrant treatment.
Treatment & Prevention
Treatments that can improve blood flow to the kidneys and reduce blood pressure include:
- Surgical removal or by-pass of the narrowing in the renal artery.
- Procedures such as angioplasty and stenting to open the blockage in the renal arteries. Angioplasty is a surgical procedure in which a tube with an attached balloon is inserted through an artery in the leg, and advanced to the renal artery. The balloon is inflated to enlarge the narrowed renal artery. A stent is a tubular device that is placed within the dilated segment of the renal artery to prevent re-narrowing or blockage of the artery.
Kidneys that are failing, or have failed, can no longer efficiently remove waste products from the body. When the waste products reach a toxic level, they can be removed artificially through dialysis, or a kidney transplant can be performed.
A person with renal failure can be treated with an artificial kidney machine (dialysis) which removes toxins from the blood. Patients requiring ongoing dialysis use the artificial kidney machine up to three times a week to manage their kidney failure.
A vascular surgeon performs a vascular access procedure to create a connection, usually an artificial graft that connects an artery and vein in the patient’s arm. This allows the dialysis machine to be connected directly to the patient’s bloodstream.
More than 88,000 patients a year receive primary vascular access procedures. An additional 130,000 undergo revision of a vascular access procedure to continue their dialysis treatments.
You can lower your risk of high blood pressure and kidney disease with a healthy lifestyle, including:
- Maintaining a healthy weight
- Increasing physical activity
- Eliminating tobacco use
- Limiting alcohol consumption to no more than 3 ounces per day for men and 1.5 ounces for women
- Building relaxation into your workday
- Developing healthy eating habits, which include selecting a variety of foods, partially whole grains, fruits and green vegetables and limiting the intake of salt and saturated fats
You can also work with your doctor to achieve good blood pressure control by:
- Knowing your blood pressure. If either the upper level systolic pressure) or lower level (diastolic pressure) goes persistently beyond the normal limit of 140/90, consult with your physician.
- Monitor your blood pressure regularly, and keep a written record to share with your doctor.
- Take medications as instructed.
- If blood pressure readings remain high, ask your doctor if tests to detect secondary hypertension should be conducted. Depending on the findings, treatment may be modified to achieve blood pressure control.
What is FAVR doing about it?
FAVR supports the research the following vascular surgeon scientists:
Eric T. Choi, MD is studying vein and artery complications in patients undergoing blood dialysis due to renal (kidney) failure. Find out more...
Alan Dardik, MD, PhD researches more effective and durable angioplasty, coronary and peripheral bypass grafts and dialysis access. Find out more...
Rajabrata Sarkar, MD, PhD is unraveling the genetic mechanism that helps in the growth of new arteries. Find out more...
