Hypertension





Arterial hypertension is a risk factor for stroke, myocardial infarction, congestive heart failure, and atherosclerosis. Yet despite the fact that treatment of hypertension reduces the risk for all of the above, only 54 percent of patients with hypertension receive treatment and only 28 percent have their high pressure adequately controlled.

As we discuss in lab, accurate measurement of the arterial pressure and confirmation of hypertension on two or more occasions is important. Also, some individuals are susceptible to "white-coat hypertension" and thus require ambulatory monitoring or at least measurement of the arterial pressure outside a clinical situation.

Sometimes arterial hypertension occurs secondarily as result of a specific disorder such as renal disease or excess mineralocorticoid secretion by the adrenal glands.

But over 90 percent of hypertension cannot clearly be identified as secondary to other causes and hence is classified as essential hypertension (primary hypertension)

Often in a younger person with essential hypertension the cardiac output is elevated. But in an older patient with established hypertension, typically it is the total peripheral resistance instead that is high.

At the same time, in younger people with hypertension, the mean arterial pressure is elevated, while the predominate pattern in the elderly is an increased pulse pressure, which is associated with decreased compliance of the arteries.

The following table is based on the recommendations of the 7th Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7).

Systolic (mm Hg) Diastolic (mm Hg)
Normal <120 and <80
Prehypertension 120-139 or 80-89
Stage 1 Hypertension 140-159 or 90-99
Stage 2 Hypertension 160 and above or 100 and above

(The JNC 8 recommendations came out fairly recently, but I have not yet updated this page, since there appears to be various ideas about the new recommendations, so I am letting things settle a bit. These recommendations are found at JNC 8 guidelines" (need to be logged in to UW). The biggest difference is that for patients over 60 without other issues, the goal is to treat to keep the systolic pressure 150 mm Hg or lower. Previous this was 140 mm Hg or lower. This is now the level for others. On the other hand, if you encountered guidelines earlier than JNC 7, you found that the levels listed for "normal" are somewhat higher. With the JNC 7 guidelines, the big difference is that diastolic pressures between 80 and 85 and systolic pressures between 120 and 129 are now considered "pre-hypertension" rather than normal.)

Additional Recommendations

Treatments

As noted above, lifestyle modifications alone are recommended at the "prehypertension" level and there are no other risk factors such as diabetes. Weight loss, although difficult, is helpful in overweight patients. A further recommendation is to engage in aerobic exercise for at least 30 to 45 minutes on most days. Another standard recommendation is to eat abundant fruits and vegetables and reduce intake of saturated fats. Restricting sodium in the diet is also usually indicated. Certain individuals, and typically the elderly, are especially sensitive to salt. But the recommendation for the population as a whole is a more complex and not an entirely resolved issue.

If lifestyle modifications prove ineffective or the hypertension is at a higher stage, drugs are used. A thiazide-type diuretic is the first choice in uncomplicated situations. The point here is to reduce the extracellular fluid volume. But sometimes a beta adrenergic blocker is used if the problem seems to arise via the heart.

More recent and more expensive drugs are ACE inhibitors and angiotensin II receptor antagonists. These act both on the extracellular fluid volume and the total peripheral resistance. A recent, large trial concluded that ACE inhibitors are no more effective than the cheaper diuretics as a first drug. However, they are often useful as a second drug if the first drug is not adequate. Also, they may be appropriate as the first drug in cases where there is a coexisting disorder such as congestive heart failure, diabetes or renal disease.

Calcium channel blockers are sometimes used to in combination with the above drugs, especially in an elderly patient at risk of stroke.

(Finally, alpha blockers are used in certain special circumstances.)




Quick Quiz: Hypertension

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Correct Answer

What is the most common type of hypertension?

What factor tends to be elevated in an elderly patient with essential hypertension?

What is the substrate of ACE?

Would an increase in the total peripheral resistance increase or decrease the mean arterial pressure?

Would an ACE inhibitor increase or decrease the total peripheral resistance?

What systolic pressure lies at the borderline for hypertension?

What organ is the primary target for the action of beta blockers when used to treat hypertension?

What type of drug is most frequently used as the first drug in hypertension uncomplicated by other disorders?

What diastolic pressure lies at the borderline for hypertension?


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