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 predominant pattern in the elderly is an increased pulse pressure, which is associated with decreased compliance of the arteries.

How is hypertension defined and when does treatment begin? There is not an easy, exact answer here. This green box contains some OPTIONAL material for reference.

JNC 7 Guidelines Released in 2004

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). This was released in 2004 and the recommendations for treatment have been superceded by later recommendations. The table defines hypertension, but does not indicate when treatment should begin. Just use this table for reference to get a general idea about the relative levels considered hypertension.


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

JNC 8 Guidelines Released in 2014

In 2014, the JNC 8 guidelines were released. These did not redefine hypertension so much as they gave extensive new guidelines about when and how to treat hypertension.

One of the major changes with JNC 8 guidelines is the recommendation for patients over 60 without other issues. In this case, pharmacological treatment should be given if systolic pressure is greater than 150 mm Hg and the diastolic pressure greater than 90 mm Hg. For others, treatment would begin if the systolic pressure is greater than 140 mm Hg or the diastolic pressure greater than 90 mm Hg.

But there are further, detailed recommendations for treatment. If you are interested, here is the 2014 article where these guidelines are presented and discussed. (You will need to be logged into UW)


ACC/AHA guidelines Released in 2017

Last November guidelines were released by American College of Cardiology and American Heart Association that very substantially altered the guidelines. It is not yet clear how these recommendations will be used. They substantially lower the definitions of hypertension and the pressures at which treatment should begin. Far more patients would need to be treated. They do indicate that out of office measurements of arterial pressure are recommended.

Systolic (mm Hg) Diastolic (mm Hg)
Normal <120 and <80
Elevated 120-129 and <80
Stage 1 Hypertension 130-139 or 80-89
Stage 2 Hypertension >140 or >90

If a patient has stage 1 hypertension and either known cardiovascular disease or a ten year risk of cardiovascular disease of greater than 10%, then beginning medication is recommended. Virtually all men over 60 would have risk calculated at 10% or higher. A calculator for this purpose can be found at risk calculator.

If a patient has stage 2 hypertension, then medication is recommended even though the patient does not show cardiovascular disease and has a risk calculated at less than 10%.

Here is the reference for these guidelines: 2017 article

Article in JAMA in March 2018

Recently an article appeared that is directed towards diabetics, but also comments on treating hypertension in general. The recommendations of these authors are more relaxed than the official guidelines published last November.

For example, they note that conditions under which the arterial pressures are measured are signficantly more rigorous in recent, high-quality clinical studies than in actual clinical practice. As a result, the pressures in clinical practice tend to be 5 to 10 mm Hg higher than in the clinical studies.

For example, the best measurements of arterial pressure have the subject seated, quiet, with feet flat on floor for at least 5 minutes. The arm would be at the proper height. Also, the best measurements would remove any "white-coat hypertension".

This article reports that the American Diabetic Association recommends a target of less than 140/90 mm Hg for most diabetics and emphasizes the need to individualize the goals for each patient. For some patients this might be less than 130/80 mm Hg.

For patients with or without diabetes, they report that "Overall, available evidence suggests that BP targets lower than less than 140/90 mm Hg yield cardiovascular benefits for some populations but increase adverse events."

Adverse effects to medication include hypotension, syncope, electrolyte abnormalities and acute kidney injury. The risk factors for such adverse effects are not well understood.

They conclude: "With this view, there is no clear rationale to change the BP thresholds used to define hypertension from 140/90 mm Hg or higher (as recommended in ADA guidelines and others) to 130/80 mm Hg or higher (as recommended by the ACC/AHA guidelines)".

Here is the reference for this article: March 2018 article

Treatments

Lifestyle modifications alone are recommended at the "prehypertension" or "elevated" levels 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 (which results in K+ supplementation), reduce intake of saturated fats, and moderate of alcohol consumptions. Restricting sodium in the diet is also usually recommended. Certain individuals, and typically the elderly, are especially sensitive to salt.

When medication is indicated, the first line drugs are thiazide-type diuretics, Ca++ channel blockers, ACE inhibitors or angiotensin II receptor antagonists. The Heart Failure webpage discusses ACE inhibitors, angiotension II receptor antagonists and diuretics. Beta blockers are also sometimes used.




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


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