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hypertension

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hypertension

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) 1)
  • high sodium diet
  • high alcohol intake
  • sedentary lifestyle
  • diabetes
  • personality traits
  • depression
  • ? role of TEM cells activated by CD70 on Antigen Presenting Cells:2)
    • 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

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
  • caffeine intake in the 0.5-4hrs prior to measurement may increase systolic BP 3-15mmHg, and diastolic BP 4-13mmHg and this needs to be taken into account, and the hypertensive effect seems greatest in males with stage 1 hypertension 3) 4)
  • 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
  • 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:

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

patient category BP target (mmHg)
adults with proteinuria > 1g/day < 125/755)
adults < 65yrs or diabetic or renal impairment or proteinuria 0.25-1g/day < 130/85 or 130/80 if diabetic6)
adults 60yrs and older without above factors < 140/90

Mx of asymptomatic high BP in the ED

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

1)
https://www.news-medical.net/news/20200611/Overactive-enzyme-causes-an-inherited-form-of-high-blood-pressure.aspx
2)
http://circres.ahajournals.org/content/circresaha/118/8/1233.full.pdf
3)
2008: Timing of blood pressure measurement related to caffeine consumption
4)
2000: Hypertension risk status and effect of caffeine on blood pressure.
5) , 6)
Aust. NHMRC 2005 - EBM guidelines for Mx of diabetes
hypertension.txt · Last modified: 2020/06/13 23:38 by gary1

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