HYPERTENSION

SALIENT FEATURES

History

· Chest pain or shortness of breath.

· Interminent claudication.

· Headaches or visual disturbances (in accelerated or severe hypertension).

· Family history of hypertension.

· Ask about hypertension during pregnancy.

· Medications.

Examination

Look for aetiology:

· Comment on Cushingoid facies if present.

· Look for radiofemoral delay of coarctation of aorta.

· Examine blood pressure in both upper arms.

· Listen for renal artery bruit of renal artery stenosis and feel for polycystic kidneys.

Look for target organ damage:

· Palpate the apex for left ventricular hypertrophy.

· Look for signs of cardiac failure.

· Examine the fundus for changes of hypertensive retinopathy.

· Tell the examiner that you would like to check urine for protein (renal failure) and sugar (associated

diabetes).

DIAGNOSIS

This patient has retinopathy (lesion) caused by hypertension, which is probably renovascular (aetiology)

as evidenced by the renal artery bruit. She probably has damage to other target organs (functional

status).

QUESTIONS

How would you record the blood pressure?

· Using a device whose accuracy has been validated and one that has been recently calibrated.

· The patient should be seated with the arm at the level of the heart. The blood pressure cuff should

be appropriate for the size of the arm and the cuff should be deflated at 2 mm/s and the diastolic

blood pressure is measured to the nearest 2 mmHg. Diastolic blood pressure is recorded as

disappearance of the sounds (phase V).

· At least two recordings of blood pressure should be made at each of the several visits to determine

blood pressure thresholds (BMJ 1999; 319: 630-5).

What are the causes of blood pressure discrepancy between the arms or between the arms and

legs?

· Coarctation of aorta

· Patent ductus arteriosus.

· Dissecting aortic aneurysm.

· Arterial occlusion or stenosis of any cause.

· Supravalvular aortic stenosis .

· Thoracic outlet syndrome.

How would you investigate a patient with hypertension in outpatients?

· Full blood count (FBC).

· Urine for sugar, albumin and specific gravity.

· Urea, electrolytes and serum creatinine.

· Fasting lipids, fasting blood sugar, serum uric acid.

· Serum total:HDL cholesterol ratio.

· ECG.

· Chest radiograph.

· 24-hour urine collection to measure vanillylmandelic acid.

What are the indications for ambulatory blood pressure recording?

· When clinic blood pressure shows unusual variability.

· When hypertension is resistant to drug treatment with three or more agents.

· When symptoms suggest that the patient may have hypotension.

· To exclude 'white-coat hypertension'.

What are causes of hypertension?

· Unknown or idiopathic (in 90% of cases).

· Renal: glomemlonephritis, diabetic nephropathy, renal artery stenosis, pyelonephritis. · Endocrine:

Cushing's syndrome, steroid therapy, phaeochromocytoma.

· Others: coarctation of aorta, contraceptives, toxaemia of pregnancy.

What special investigations would you perform to screen for an underlying cause?

· Renal digital subtraction angiography.

· 24-hour urinary catecholamines - at least three samples (phaeochromocytoma). · Overnight

dexamethasone suppression test.

What are the British Hypertension Society Guidelines for initiating hypertensive agents?

· Sustained systolic blood pressure > 160 mmHg or sustained diastolic blood pressure ?> 100 mmHg.

· To determine the need for treatment in those with mild hypertension (systolic blood pressure

between 140 and 159 mmHg or sustained diastolic blood pressure between 90 and 99 mmHg)

according to the presence of target organ damage, cardiovascular disease, diabetes or a 10-year

coronary heart disease risk of > 15%, according to the Joint British Societies Coronary Heart Disease

Risk Assessment Program (BMJ1999; 319: 630-5).

What are the optimal treatment targets?

The optimal treatment targets are systolic blood pressure < 140 mmHg and diastolic blood pressure < 85

mmHg. The minimum acceptable level of control is 150/90 mmHg (BMJ 1999; 319: 630-5).

What is the purpose of treatment in hypertension?

The purpose is to reduce the risk of devastating hypertensive complications such as myocardial

infarction, stroke and heart failure.

How would you manage a patient with mild hypertension?

General measures

· Diet: weight reduction in obese patients, low-cholesterol diets for associated hyperlipidaemia, salt

restriction. Increased consumption of fruit and vegetables.

· Regular physical exercise that should be predominantly dynamic (for example brisk walking) rather

than isometric (weight lifting).

· Limit alcohol consumption (<14 units per week for women and <21 units/week for men).

· Stop smoking.

Antihypertensives

Beta-blockers or low-dose thiazides.

Other drugs

Aspirin, statins.

Why are diuretics and beta-blockers recommended as first-line agents in the management of

hypertension?

Until recently, evidence about the effects of blood pressure lowering agents on the risks of cardiovascular

complications came exclusively from trials of diuretic-based or beta-blocker based regimens in the

hypertensive population. Those trials collectively showed reductions in risk of stroke and coronary heart

disease of about 38% and 16% respectively (Br Med Bull 1994; 50: 272-98) and reductions in the risk of

heart failure of about 40% (Hypertension 1989; 13 (5 suppl): 174-9: JAMA 1997; 278: 212-16).

What is the role of alpha-blocker based regimens in the control of blood pressure ?

The Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack (ALLHAT) trial showed that

an alpha-blocker based regimen is less efi'ective than a diuretic-based regimen in preventing heart failure

(JAMA 2000: 283: 1967-75). Additionally, there was a marginally significant excess of stroke in the

alpha-blocker group. Although poorer blood pressure control might account for the higher risk of stroke, it

does not entirely explain the two-fold greater risk of heart failure.

What is the role of calcium channel blockers in the treatment of hypertension ?

· In the SYST-EUR study nitrendipine showed a reduction in the risk of stroke

inisolated systolic hypertension when compared to diuretics (Lancet 1997; 350: 757-64).

· In the Swedish Trial in Old Patients with Hypertension-2 (STOP-2) study, there was some evidence

that the risks of myocardial infarction and of heart failure were greater with calcium antagonist based

therapy than with ACE-inhibitor based therapy, but there were no clear differences between either of

these regimens and a third based on diuretics and beta-blockers (Lancet 1999; 354: 1751-6). In this

study 34-39% of patients withdrew from the three treatment regimens.

· The International Nifedipine GITS Study: Intervention as a Goal in Hypertension Treatment

(INSIGHT) trial compared long-acting nifedipine with a diuretic (hydrochlorothiazide and amiloride

combination) and found that the calcium channel antagonist was as effective as diuretics in

preventing overall cardiovascular or cerebrovascular complications (Lancet 2000; 356: 366-72).

There was a marginally significant excess of heart failure with nifedipine-based treatment. Fatal

myocardial infarctions were more common in the nifedipine group. There was an 8% excess

withdrawal of drug in the nifedipine group because of peripheral oedema whereas serious adverse

events were more frequent in the diuretic group.

· In the Nordic Diltiazem Study (NORDIL) from Sweden diltiazem was compared with diuretics,

beta-blockers or both (Lancet 2000; 356: 359-65). This study found that diltiazem was as effective as

treatment based on diuretics, beta-blockers or both in preventing the primary end point of all stroke,

myocardial infarction and other cardiovascular deaths. There was a marginally significant lower risk of

stroke in the diltiazem group despite a lesser reduction in blood pressure. In this study, 23% of the

patients withdrew from the diltiazem-based group and 7% withdrew from diuretic-based and

beta-blocker based therapy.

What is the role of ACE inhibitors in hypertension?

· In the HOPE (Heart Outcomes Prevention Evaluation) study the use of ramipril was associated with

reductions of stroke, coronary artery disease and heart failure in both hypertensive and

non-hypertensive groups as compared to placebo (N Engl J Med 2000; 342: 145-53).

· In the Captopril Prevention Project (CAPPP) the risk of stroke was slightly greater with ACE inhibitor

based therapy than with diuretic-based or beta-blocker based therapy but the higher baseline and

follow-up blood pressure among patients assigned the ACE inhibitor regimen may largely or entirely

account for the excess risk of stroke (Lancet 1998; 353:611-16).

What are the indications for specialist referral?

· Hypertensive emergency: malignant hypertension, impending complications.

· To investigate possible aetiology when evaluation suggests this possibility.

· To evaluate therapeutic problems or failures

Special circumstances: unusually variable blood pressure, possible white-coat hypertension, pregnancy

(BMJ)