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Diagnosis, assessment, and treatment of essential hypertension 

Diagnosis, assessment, and treatment of essential hypertension

Chapter:
Diagnosis, assessment, and treatment of essential hypertension
Author(s):

Bryan Williams

and John D. Firth

DOI:
10.1093/med/9780199204854.003.161702_update_001

Update:

This chapter has been substantially re-written to accommodate changes in European, American (Joint National Committee [JNC] 8), and British (British Hypertension Society/NICE) guidelines for the diagnosis and management of hypertension. New sections have been added on non-pharmacological treatments for hypertension: renal denervation and baroreflex activation therapy.

Updated on 29 Oct 2015. The previous version of this content can be found here.
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date: 25 March 2017

Essential hypertension is almost invariably symptomless, and usually detected by routine screening or opportunistic measurement of blood pressure. Key questions to answer in the assessment of a person presenting with an elevated blood pressure are: (1) Do they have hypertension, i.e. is the blood pressure persistently elevated? (2) Are there any associated clinical features that might warrant further evaluation to exclude secondary causes of hypertension? (3) Are there factors that might be contributing to an elevated blood pressure, including lifestyle or dietary factors or concomitant medication? (4) Is there any associated target organ damage or comorbidity that influences the overall cardiovascular disease risk and subsequent treatment of the patient?

Diagnosis

It is normal to find large variations in blood pressure measured in a single individual, hence it should be measured as accurately as possible using the British Hypertension Society protocol. All adults should have their blood pressure measured routinely at least every 5 years. Automated home blood pressure measurements (HBPM) and ambulatory blood pressure measurement (ABPM) recordings provide much more information than standard office blood pressure measurements with regard to diagnosis and efficacy of treatment of hypertension and some recent guidelines recommend that they should be used routinely for diagnosis.

The appropriate thresholds for diagnosis of hypertension depending on the method of blood pressure measurement are (1) office or clinic—systolic blood pressure (SBP) 140 mmHg, diastolic blood pressure (DBP) 90 mmHg; (2) ABPM 24 h—SBP 130 mmHg, DBP 80 mmHg; daytime—SBP 135 mmHg, DBP 85 mmHg; night-time—SBP 120 mmHg, DBP 70 mmHg; and (3) home measurements—SBP 135 mmHg, DBP 85 mmHg. The European Society of Hypertension classification of hypertension is described in Chapter 16.17.1.

Isolated office hypertension (‘white coat’ hypertension) should be diagnosed whenever office blood pressure is greater than or equal to 140/90 mmHg on at least three occasions, while 24-h mean and daytime blood pressures are within their normal range.

Clinical examination and investigation

Fundoscopy is the most convenient method of directly visualizing vascular pathology and provides important prognostic information. Three grades are recognized: (1) mild—generalized and focal arteriolar narrowing, arteriolar wall opacification, and arteriovenous nipping; (2) moderate—as (1) plus flame-shaped blot haemorrhages and/or cotton wool spots and/or hard exudates and/or microaneurysms; and (3) severe—as (2) plus swelling of the optic disc.

Aside from measurement of blood pressure and fundal examination as detailed above, particular features to look for on examination are evidence of secondary effects of sustained hypertension on the heart, and features that might suggest the presence of a secondary cause of hypertension (coarctation—absent/delayed femoral pulses, cardiac murmur; and renovascular disease—renal bruit).

Patients with essential hypertension need only a limited number of routine investigations, namely (1) urine strip test for blood and urinary albumin:creatinine ratio (ACR) for proteinuria; (2) serum creatinine and electrolytes; (3) blood glucose—ideally fasted; (4) cholesterol and HDL-cholesterol—ideally fasted; and (5) electrocardiogram (ECG).

Management

The treatment of hypertension is directed towards reducing risk rather than treating symptoms and best advice and treatment is informed by formal estimation of a patient’s overall cardiovascular risk.

There is international consensus that, for office blood pressure, an optimal treatment target should be less than 140/90 mmHg, in patients under the age of 60 years. Recommendations differ for older patients: current American guidelines suggest treating to a goal of less than 150/90 mmHg for patients aged over 60 years, whereas the British Hypertension Society/NICE guideline recommends the same higher target for those over 80 years. Most international guidelines no longer recommend lower blood pressure targets for populations at higher cardiovascular rise, e.g. patients with diabetes although the most recent European guideline suggests a target for DBP of below 85 mmHg in this group. Although early studies focused primarily on DBP as the treatment target, SBP is invariably more difficult to control and should be the main focus of treatment.

The most effective lifestyle interventions for reducing blood pressure are (1) modifications to diet to induce weight loss, (2) regular aerobic exercise, and (3) reduction of excessive in alcohol and/or sodium intake all smokers should be offered advice and help to quit to reduce cardiovascular (and other) risks. Many patients will require more than one drug to control blood pressure: monotherapy is rarely sufficient. The blood pressure response to an individual class of blood pressure-lowering medication is heterogeneous, hence there is no ‘perfect drug’ for every patient, but some trials have indicated that certain comorbidities or target organ damage provide compelling indications for inclusion of specific classes of drug therapy in the treatment regimen.

There is wide variation in the international guidelines with regard to the preferred initial therapy for essential hypertension: (1) the (American) Joint National Committee (JNC) guideline recommends initial drug treatment with an angiotensin converting enzyme inhibitor (ACE inhibitor), angiotensin receptor blocker (ARB), calcium channel blocker (CCB), or thiazide-type diuretic (TTD) in nonblack hypertensive patients with a CCB or TTD preferred in black patients; (2) the recent European guideline suggests that all five main classes of blood pressure-lowering drugs ACE inhibitor, ARB, β‎-blockers, CCB, and TTD) are all suitable as initial therapy; (3) the British Hypertension Society/NICE guideline suggests that the most appropriate initial blood pressure lowering agent for (a) people aged 55 years or over, and for black people of African or Caribbean family origin of any age, is a CCB, with a TTD preferred if a CCB is not suitable, and (b) for people under 55 years of age an ACE inhibitor or a low-cost ARB is preferred initial therapy.

All guidelines recognize that combinations of blood pressure lowering drugs are often required to achieve recommended blood pressure goals, European guidelines suggest various suitable combinations of treatments. American guidelines recommend selecting any two of the medications recommended as suitable for the particular patient as initial therapy. The British guideline provides explicit guidance on preferred combinations of treatment at if one agent fails to achieve adequate control: step 2, CCB combined with either an ACE inhibitor or ARB; step 3, add a TTD; step 4—add higher-dose TTD, spironolactone, an α‎-blocker or a β‎-blocker.

Patients with hypertension and deemed to be at high cardiovascular risk (>20% over 10 years) should receive advice to adjust their lifestyles and be considered for treatment with statin therapy and low-dose aspirin to optimize their risk reduction.

Indications for specialist referral include uncertainty about the decision to treat, investigations to exclude secondary hypertension, severe and complicated hypertension, and resistant hypertension.

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