hypertension
Table of Contents
hypertension
Introduction
- it is important that BP be measured correctly:
- cuff should be at the level of the heart
- cuff should be the correct size for the patient
- arm should be resting on a desk - arm resting on the lap or unsupported gives BP readings 4-9mmHg higher 1)
- consider measuring BOTH arms in case there is a difference due to anatomy (or rarely a type B aortic dissection)
- when assessing for Rx of hypertension, it should be done when the patient is relaxed and not anxious and repeated over days or weeks to confirm
risk factors for hypertension
- older age
- obesity
- genetics:
- 2x risk if parent has HT, higher incidence in those of African descent
- rare familial causes:
- hypertension and brachydactyly (HTNB) syndrome (Bilginturan syndrome) due to a faulty, over-active form of phosphodiesterase 3A (PDE3A) 2)
- high sodium diet
- high tellurium levels from food contamination 5)
- high alcohol intake
- sedentary lifestyle
- diabetes
- personality traits
- depression
- ? role of TEM cells activated by CD70 on Antigen Presenting Cells:6)
- these memory cells can be long lived, lasting decades, and reside in the bone marrow and can potentially sensitize the host to repeated mild hypertensive stimuli and may play a critical role in salt-sensitive and angiotensin II–induced hypertension
- these cells are major sources of IL-17A and IFN-γ, which are thought to be prime mediators of hypertension
- recurrent hypertensive stimuli which appear to activate CD70 and TEM cells include:
- emotional stress
- catecholamine surges in sleep apnea
- repeated bouts of excess sodium intake
secondary causes of hypertension
- medications such as:
- sympathomimetics such as pseudoephedrine, amphetamines, cocaine
- renal disease
- renovascular disease
-
- eg. daily transient adrenal adenoma hyper-aldosteronism
- discovered in 2023 7)
- generally requires 24hr urine aldosterone to detect as serum levels may miss the transient rises
- caused by a somatic mutation in aldosterone-producing adenomas of the gene which produces a protein called CADM1
- seems to the the cause of 5-10% of cases of hypertension
- Rx is unilateral adrenalectomy
- obstructive sleep apnoea
- Cushing's syndrome
- coarctation aorta
- possibly, but unproven:
- cervical spondylosis / cervical disc prolapse (often also causes vertigo, headaches which are not due to vertebrobasilar insufficiency from cervical disease, but perhaps due to stimulation of sympathetic nerve fibres around the proximal vertebral artery or perhaps due to pain)
- chronic pain syndromes
initial Dx of hypertension
- if no end organ damage evident, Dx is usually best made on at least 3 BP checks over a period of weeks and taking into consideration white coat false positive BP values
- BP should be similar in both arms and if more than 15mmHg, one should suspect subclavian stenosis and peripheral vascular disease (PVD or PAD), or in the context of chest pain, the life threatening emergency of aortic dissection
- in the adult:
- Stage 1 hypertension = systolic 140 to 159 mmHg or diastolic 90 to 99 mmHg
- Stage 2 hypertension = systolic ≥160 mmHg or diastolic ≥100 mmHg
initial Ix of newly diagnosed hypertension
assess end organ damage:
- CXR, ECG, U&E, urinalysis
- fundus exam for retinopathy
- if evidence of cardiac failure, LV dysfunction, then consider echocardiogram
- consider a random timed urine albumin-to-creatinine ratio
assess potential life style modifications:
- cease smoking
- weight control
- reduce dietary sodium to 4g (65mmol) per day - see salt / sodium in food products
- increase fruit and vegetables in diet
- seems to improve eGFR in patients with HT 10)
- start aerobic exercise 3 x 10min per week initially then increase
- avoid heavy weight-lifting / Valsalva until BP under control
- medications known to increase BP
assess other risk factors:
- fasting lipids, glucose
consider targeted approach to excluding secondary causes in subgroup of:
- prepubertal onset
- age < 30 with no overt risk factors
- presentation in Stage 2
- severe HT (> 180/120 mmHg) at age > 55yrs or with small kidney (<9cm or > 1.5cm smaller than other kidney)
- acute rise in BP or malignant HT
- renal impairment with sustained rise of > 50% in serum CRN after starting ACE inhibitors
- resistant hypertension
- flash acute pulmonary oedema (APO) ⇒ ?renovascular
- paroxysmal high BP ⇒ phaeochromocytoma
- hypokalaemia ⇒ ? aldosteronism
- abdominal bruit ⇒ ? renovascular
- Cushingoid
- sleep apnoea risk
- brachio-femoral delay ⇒ ? coarctation
- renal impairment or abnormal urinalysis
initial Rx of hypertension without end organ damage
- life style modications
- sodium restriction to 100mEq/d may reduce BP by up to 5mmHg and reduce age-related increases
- weight loss gives 0.5-2mmHg reduction per kg lost
- cut down on caffeine intake
- avoid sympathomimetic agents such as pseudoephedrine
- DASH diet gives additive benefits to modest sodium restriction
- limit alcohol intake to 2 glasses a day (1 glass/day for women) and have at least 2 alcohol free days per week
- increase aerobic exercise may reduce BP by ~4mmHg
- ensure at least 6hrs sleep each night as long term sleep deprivation increases risk of hypertension
- cease smoking to avoid the compounding effects on atherosclerosis
- initial pharmacologic Rx:
- if diabetic or proteinuria then ACE inhibitors
- if ischaemic heart disease or other compelling reason, then beta adrenergic blockers
- if black or African American, then diuretic or long acting calcium blocker
- ACE inhibitors are less potent and less effective in lowering blood pressure in black adults compared to white patients due to lower renin levels and higher salt sensitivity, genetic polymorphisms in the angiotensinogen gene, and differences in how the intrarenal renin-angiotensin system responds to salt intake
- if BP > 20/10mmHg above goal then consider ACE inhibitors + long acting calcium blocker
US targets 2014
| patient category | BP target (mmHg) |
|---|---|
| most adult patients under 60yrs | < 140/90 |
| most adult patients 60yrs and over | < 150/90 |
targets as of 2007
Mx of asymptomatic high BP in the ED
- this group of patients are those who:
- are not pregnant (see pre-eclampsia and eclampsia),
- not on dialysis,
- do not have overt evidence of end-organ complications:
- hypertensive encephalopathy
- they thus do NOT need Ix in ED
- ECG, CXR, blood tests are NOT needed in the ED - they can be arranged as OP by LMO
- they also do NOT need urgent Rx in ED
- see ACEP guidelines
- rest is generally as good as acute Rx, however, oral antihypertensive such as amlodipine 5mg may be considered
urgent reduction of blood pressure in the ED in hypertensive "emergency"
- usually indicated if severe HT with diastolic > 120mmHg with end organ affects
- may be indicated with other conditions where high BP is not desirable
- see pre-eclampsia and eclampsia for Mx in pregnancy
parenteral Rx in resus setting with close haemodynamic monitoring
- if there is encephalopathy, see posterior reversible encephalopathy syndrome (PRES) as iv labetalol may be the preferred Rx
- otherwise, consider:
- sodium nitroprusside 0.3 microgram/kg/minute IV for 10 minutes, then increasing or decreasing by 0.3 microgram/kg/minute every 5 to 10 minutes (up to a maximum of 10 micrograms/kg/minute), or,
- hydralazine 5 to 10 mg slowly IV, repeating at 20 minute intervals if necessary, or,
- GTN infusion
oral Rx when Rx is less urgent
- amlodipine 5-10mg o
- patients with myocardial ischaemia, consider using a beta blocker with or without amlodipine
podcasts and other references
hypertension.txt · Last modified: 2024/10/09 22:56 by gary1