18 August 2007

Hypertension - What causes it?

What causes Hypertension (High Blood Pressure)

Two main types of hypertension are recognized. By far the most common is Essential Hypertension, sometimes called Primary Hypertension. This is hypertension in which there is no identifiable cause. Ninety five percent of all persons living with hypertension have essential hypertension. Although researchers have been unable to pinpoint its specific causes, several risk factors definitely increase an individual's chance of developing essential hypertension. Some of these risk factors are controllable. They include:

  • Obesity
  • High Salt Intake
  • Smoking
  • Lack of Exercise
  • Emotional and/or Physical Stress

Risk factors that cannot be controlled are:

  • Gender--Males are at a higher risk for hypertension at earlier ages than females.
  • Age--The risk goes up for older women; more than half of women over the age of 60 have high blood pressure.
  • Race--Hypertension and its complications are more common among people of African ancestry than among members of other ethnic groups. Not only does hypertension typically begin earlier among African-Americans; its complications are more frequent, and it leads to death more often.
  • Family History of Hypertension--Risk is higher in people whose parents also have high blood pressure.

The other major type of hypertension, termed Secondary Hypertension, has an identifiable cause. It is due to disease. For example, kidney (renal) hypertension is due to high blood pressure within the arteries that supply blood to the kidneys. The underlying cause is kidney disease or conditions like atherosclerosis, which narrow or block the renal arteries. Secondary hypertension may also result from hormonal imbalances, particularly in the kidney's adrenal glands. Cushing's syndrome and pheochromocytoma (pronounced: “fee–oh–chrome–oh–sigh–toe–ma”), which is a tumor of the adrenal glands, are two of the conditions that can disrupt adrenal hormones and lead to secondary hypertension. Other causes of secondary hypertension include pregnancy, thyroid disease, and the use of some medications such as oral contraceptives and non-steroidal anti-inflammatory medications (NSAIDs).


12 August 2007

Treatments for Heart Failure

How is Heart Failure treated?

The management of heart failure (HF) depends on its cause and clinical course. Since high blood pressure, coronary artery disease, high cholesterol, and valvular heart disease are common causes of HF, aggressive management of these conditions is essential. Treatment goals include:

  • Improve the individual’s quality of life and symptoms
  • Prevent the heart failure from worsening
  • Prolong the individual’s life span
  • Treat the underlying cause of the heart failure.

    When a person is diagnosed with HF, both non-drug (described in "Helping Yourself") and drug therapy is recommended. All patients with chronic HF due to left ventricle systolic dysfunction (means the heart muscle itself is weakened and not able to pump blood out of the heart as effectively as before) should receive an angiotensin-converting enzyme inhibitor (ACE-Inhibitor), unless the person is intolerant to or has a contraindication to the use of this class of drugs. ACE-Inhibitors are "vasodilators," which cause the peripheral blood vessels to dilate, or open up. This reduces the work of the heart by making it easier for blood to flow.

    ACE-Inhibitors should even be used in HF patients who do not yet have symptoms of HF because these drugs have been shown in clinical studies to reduce the risk of disease progression and improve patient survival. In patients with fluid retention, ACE-Inhibitors are typically combined with diuretics.

    Diuretics (aka, “water pills”), available since the 1950s, are used to help the kidneys get rid of excess water and sodium, thereby reducing blood volume and the heart's workload. These drugs can help alleviate HF symptoms like shortness of breath and lower extremity edema (fluid collection in the feet, ankles, & lower legs).

    Patients who cannot tolerate ACE-Inhibitors should be treated with angiotensin II receptor blockers (ARBs). ARBs have been shown to improve survival in persons who have HF.

    There may be special situations when a combination of an ACE-Inhibitor and ARB may be used. However, the role of this combination is not well-defined and is somewhat controversial.

    Other "vasodilators" such as a combination of hydralazine plus nitrate therapy may be used if patients cannot tolerate either ACE-Inhibitors or ARBs. The hydralazine and nitrate combination is considered a second-line therapy and should not be used for the treatment of HF in patients who have not been previously treated with an ACE-Inhibitor. A new drug called BiDil combines hydralazine and isosorbide dinitrate into one tablet. BiDil was shown in one study to improve survival in African American persons who have HF.

    Beta-blockers are also a first-line recommendation for HF patients. These drugs decrease the heart rate as well as the overall work of the heart through vasodilation. Certain beta-blockers have been shown in clinical studies to reduce the risk of death associated with HF. All persons with stable, mild-to-moderate or moderate-to-severe HF due to left ventricular dysfunction (who do not have intolerance or contraindications) should have a beta-blocker (either bisoprolol, carvedilol, or metoprolol succinate) added to a regimen of an ACE-Inhibitor and a diuretic as early as possible.

    Some clinicians recommend using digitalis (digoxin), a drug that has been used since the 18th century, to strengthen the heart's pumping action. Other clinicians contend that digitalis has not been shown to affect the normal course of HF. They recommend that it should be reserved for patients who still have symptoms of HF after being treated with an ACE-Inhibitor, diuretic, and a beta-blocker or for those patients who also have atrial fibrillation. While digoxin has not been adequately shown in clinical studies to reduce death from HF, it has been shown to improve HF symptoms and patient quality of life. Patients taking both diuretics and digitalis may need to supplement their levels of potassium.

    In patients with severe heart failure, another type of diuretic can be added to treatment regimens consisting of an ACE-Inhibitor, diuretic, beta-blocker, and digoxin. Spironolactone (brand name: Aldactone), a potassium-sparing diuretic, has been shown in clinical studies to reduce mortality in patients with severe heart failure and thus, may be considered for use in these patients. Spironolactone blocks the action of aldosterone, a hormone that may exert adverse effects on the heart muscle and peripheral blood vessels. Spironolactone not only may improve fluid balance but may also decrease the risk of progression of HF. For patients with more severe forms of HF, spironolactone has been shown in clinical studies to reduce hospitalizations and death from heart failure. Spironolactone's efficacy and safety in patients with mild to moderate HF remains unknown.

    Most recently, eplerenone (Inspra) received FDA approval for the treatment of heart failure that occurs following a heart attack. Eplerenone is a selective aldosterone receptor blocker, the first drug in this class. Individuals may be candidates for eplerenone therapy if they have documented heart failure proceeding a heart attack. For more information on the use of eplerenone following a heart attack, talk to your doctor or primary health care provider.

    Sometimes, surgery proves effective. When HF is due to disease of the heart valves, surgery to repair the valve or implant an artificial heart valve may be helpful. Surgery is also used to correct congenital heart defects that can lead to HF. When HF is caused by partial or complete blockage of the coronary arteries, coronary bypass surgery or angioplasty may be used.

    Heart transplants are a last resort in treating severe HF caused by diseased heart muscle. Although the success rate of heart transplants has significantly improved, the cost of the operation and shortage of donor organs makes it impractical except as a last resort.

    Drug classes used to treat Heart Failure

    ACE-Inhibitors

    Aldosterone Receptor Blockers

    Angiotensin II Receptor Blockers

    Beta Blockers

    Cardiac Glycosides

    Diuretics

    Selective Aldosterone Receptor Antagonist

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