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Hypertension (High Blood Pressure)

Blood pressure

What is Hypertension (High Blood Pressure)?

Hypertension

Hypertension is defined as elevated blood pressure and is the leading cause globally of death and disability. It is the major risk factor for heart attack and stroke, and is also a significant risk factor for for chronic kidney disease and chronic heart failure. Because individuals with hypertension usually don’t have any symptoms, it is a disease that is often under-diagnosed. Diagnosis relies upon routine blood pressure screening to monitor and detect affected individuals.

Statistics

 In 2000, it was estimated that nearly one billion individuals worldwide were hypertensive. This figure equates to approximately 26.4% of the total global adult population.

The Australian Diabetes, Obesity and Lifestyle Study (AusDiab) conducted in 1999–2000 reported that 30% of Australians (32% of males and 27% of females) over 25 years of age, or 3.7 million Australians, were hypertensive (blood pressure > 140/90 mmHg).

In general, males are more likely to have hypertension than females, except for between the ages of 45 and 64, when females are at equal risk to males.

The incidence of hypertension is three times higher in Indigenous Australians compared to non-indigenous Australians.

 

Risk Factors

Approximately 95% of hypertension cases are classified as essential or primary hypertension, in which the underlying cause is unknown. The remaining cases are classified as secondary hypertension, in which there is an identifiable cause (e.g. renal artery stenosis).

Major studies have identified the following factors as key predisposing factors for hypertension:

Factors that have been identified in the Australian 2008 National Heart Foundation Hypertension Guidelines include:

  • Sedentary lifestyle;
  • Smoking;
  • Waist measurement > 94 cm in men and 80 cm in women, or BMI > 25;
  • High dietary salt intake; and
  • Alcohol consumption.

Progression

If hypertension remains uncontrolled, it ultimately leads to end organ damage. Hence, uncontrolled hypertension is the major risk factor for coronary artery disease and stroke – two important endpoints in the disease process.

Similarly, chronic renal failure, diabetes, eye disease, erectile dysfunction and chronic heart failure are also significant diseases associated with the progression of uncontrolled or poorly controlled hypertension.

Symptoms

Most people with hypertension are unaware that they have a problem. This is because hypertension has few, if any symptoms. Therefore, primary hypertension is usually detected through routine screening when visiting a GP. Longterm uncontrolled hypertension is associated with an increased risk of heart attack and stroke, amongst other diseases.

Clinical Examination

Hypertension is assessed via the measurement of blood pressure. A diagnosis of hypertension can be made if, after several readings on separate occasions, an elevated value is consistently recorded.

As a guide, a blood pressure reading greater than 140/90 taken on three different occasions is sufficient to diagnose hypertension.  Ambulatory blood pressure monitoring can also be used to assess average blood pressure readings over a 24 hour period.

In addition to blood pressure measurement, a full cardiovascular exam should be performed, noting any signs of an enlarged heart or arterial disease. Additional examinations that should be included if hypertension is suspected include an eye exam, waist circumference and body mass index.

For more information, see blood pressure investigation.

Blood Pressure Calculator
This risk assessment tool is based on data from the National Heart Foundation´s Guide to management of hypertension 2008. It puts your blood pressure measurement into one of the seven diagnostic categories specified in this guide.
Age years
Gender Male / Female
Blood pressure* / mmHg
*Use current blood pressure, regardless of whether the person is on antihypertensive therapy.

Results

Normal
Your blood pressure should be rechecked within 2 years or earlier depending on your risk of developing cardiovascular disease. Your General Practitioner can advise you about this risk and also on lifestyle risk reduction.
High-Normal
Your blood pressure is elevated. It should be rechecked within 12 months or earlier depending on your risk of developing cardiovascular disease. Your General Practitioner can advise you about this risk and also on lifestyle risk reduction.
Grade 1 (mild) Hypertension
Your blood pressure is elevated. It should be confirmed within 2 months. Your General Practitioner should advise you about lifestyle risk reduction and/or medication to lower your blood pressure.
Grade 2 (moderate) Hypertension
Your blood pressure is elevated. It should be confirmed within 1 month and you may also need to see a specialist in this time. Your General Practitioner can advise you about lifestyle risk reduction and/or medication to lower your blood pressure.
Grade 3 (severe) Hypertension
Your blood pressure is elevated. It should be confirmed within 1 week and you may also need to see a specialist in this time. Your General Practitioner can advise you about lifestyle risk reduction and/or medication to lower your blood pressure.
Isolated systolic hypertension
Your systolic blood pressure is elevated. Depending on the level it needs to be confirmed within a certain time (140-159mmHg - 2 months; 160-179mmHg - 1 month; >180mmHg - 1-7 days).You may also need to see a specialist. Your General Practitioner can advise you about lifestyle risk reduction and/or medication to lower your blood pressure.
Isolated systolic hypertension with widened pulse pressure
Your blood pressure is elevated. It should be confirmed within 1 week and you may also need to see a specialist in this time. Your General Practitioner can advise you about lifestyle risk reduction and/or medication to lower your blood pressure.
Hypotension
Your blood pressure is lower than normal. Your General Practitioner will ask you about symptoms that you may be experiencing and determine if you require treatment or further investigation.


References
  1. National Heart Foundation of Australia. Your blood pressure 2008. http://www.heartfoundation.org.au/document/NHF/A_Hypert_Guidelines2008_
    ISC_YourBloodPressure_FINAL.pdf
    (accessed November 15, 2008).
  2. Chesnut RM, Marshall LF, Klauber MR, Blunt BA, Baldwin N, Eisenberg HM, Jane JA, Marmarou A, Foulkes MA. The role of secondary brain injury in determining outcome from severe head injury. J Trauma; 34: 216-222

This information will be collected for educational purposes, however it will remain anonymous.

How is it Diagnosed

Some investigations that may be ordered to assist with diagnosis include:

  • Dipstick urinalysis for blood and protein;
  • Urinalysis: Spot urine albumin/creatinine ratio
  • Blood tests: Urea and electrolytes, lipid profile and fasting blood sugar.
  • ECG: To assess for heart enlargement.

More specific investigations may also be required, including:

  • Renal artery duplex ultrasoundto exlude renal disease if suspected;
  • Renal CT angiography to look for renal artery stenosis;
  • Echocardiogarphy to assess for an enlarged heart;
  • Carotid Doppler; and
  • Plasma aldosterone/renin ratio.

Prognosis

Hypertension at 50 years of age is associated with a 5 year reduction in life expectancy. If hypertension is properly controlled, the risk of stroke reduces by more than the risk of heart attack.

Treatment

HypertensionThe decision about how and when to intervene with hypertension is dependent upon the severity of the diagnosis, the absolute cardiovascular risk profile and the evidence of end organ damage.


Immediate medical intervention

Immediate treatment is required with any of the following:3,15,16,19

  • Severe hypertension;
  • Evidence end organ damage (regardless of blood pressure);
  • Diabetes where BP > 140/90 mmHg;
  • High absolute cardiovascular risk measurement; and
  • Indigeneity.


Lifestyle modification

In all circumstances, the first management step is lifestyle modification, focusing on:

  • Regular physical activity (minimum 30 minutes a day moderate intensity);
  • Smoking cessation;
  • Dietary modification (salt intake < 4 g/day, plenty of fruit and vegetables, low fat);
  • Weight and waist reduction (aim for BMI < 25, waist < 94 cm (men), 80 cm (women)); and
  • Limit or avoid alcohol (one standard drink per day).


Medications

Four major classes of drug are routinely used:

  • Diuretics (especially thiazide diuretics);
  • Angiotensin converting enzyme inhibitors and the related angiotension II receptor blockers;
  • Calcium channel blockers; and
  • Beta-blockers.

All of the drug classes appear to have similar short and medium term protective effects, however, issues of tolerability may lead to beta-blockers being considered a second line medication.

Most drugs take 4–8 weeks for maximum effect. Thus, it is recommended that a minimum period of 6 weeks is trialled before changes to medications are made.Generally treatment starts with a single drug. Recent large studies have shown that cheaper, older drugs, are just as effective as newer drugs. If a single drug fails to achieve blood pressure goals, other agents can be added in.

More information

Hypertension
For more information on high blood pressure, including investigations and treatments, as well as some useful animations, videos and tools, see Hypertensions (High Blood Pressure)
.

References

  1. Hypertension. Stedman’s Medical Dictionary [27th edition]. Baltimore: Lippincott Williams and Wilkins; 2000. 855.
  2. Lopez AD, Mathers CD, Ezzati M, Jamison DT, Murray CJ. Global and regional burden of disease and risk factors, 2001: Systematic analysis of population health data. Lancet. 2006; 367(9524): 1747-57.
  3. National Blood Pressure and Vascular Disease Advisory Committee. Guide to management of hypertension 2008 [online]. National Heart Foundation of Australia. 1 August 2008 [cited 20 March 2009]. Available from URL http://www.heartfoundation.org.au/ SiteCollectionDocuments/ A%20Hypert%20Guidelines2008%20Guideline.pdf  
  4. Kearney PM, Whelton M, Reynolds K, Muntner P, Whelton PK, He J. Global burden of hypertension: Analysis of worldwide data. Lancet. 2005; 365(9455): 217-23.
  5. Dunstan D, Zimmet P, Welborn T, Sicree R, Armstrong T, Atkins R, et al.  Diabetes & Associated Disorders in Australia 2000: The Australian Diabetes, Obesity and Lifestyle Study (AusDiab). Melbourne: International Diabetes Institute; 2000.
  6. Barr ELM, Magliano J, Zimmet P, Polkinghorne K, Atkins A, Dunstan D, et al. AusDiab 2005: The Australian Diabetes, Obesity and Lifestyle Study. Melbourne: International Diabetes Institute; 2005.
  7. Parikh NI, Pencina MJ, Wang TJ, Benjamin EJ, Lanier KJ, Levy D, et al. A risk score for predicting near-term incidence of hypertension: The Framingham Heart Study. Ann Intern Med. 2008; 148(2): 102-10.
  8. Chiong J, Aronow W, Khan I, Nair C, Vijayaraghavan K, Dart R, et al. Secondary hypertension: Current diagnosis and treatment. Int J Cardiol. 2008; 124(1): 6-21
  9. Kumar P, Clark M. Clinical Medicine [6th edition]. New York: W.B. Saunders; 2005. 787.
  10. Kumar V, Abbas A, Fausto N. Robbins and Cotran Pathologic Basis of Disease [7th edition]. Philadelphia: Elsevier Saunders; 2005. 529-30.
  11. Grosso A, Veglio F, Porta M, Grignolo FM, Wong TY. Hypertensive retinopathy revisited: Some answers, more questions. Br J Ophthalmol. 2005; 89(12): 1646-54.
  12. Manolis A, Doumas M. Sexual dysfunction: The ‘prima ballerina’ of hypertension-related quality-of-life complications. J Hypertens. 2008; 26(11): 2074-84.
  13. Franco OH, Peeters A, Bonneux L, de Laet C. Blood pressure in adulthood and life expectancy with cardiovascular disease in men and women: Life course analysis. Hypertension.  2005; 46(2): 280-6.
  14. Lawes CM, Bennett DA, Feigin VL, Rodgers A. Blood pressure and stroke: An overview of published reviews. Stroke. 2004; 35(4): 1024.
  15. New Zealand Guidelines Group. The assessment and management of cardiovascular risk. Best practice evidence based guideline. Wellington: New Zealand Guidelines Group; 2003.
  16. Chobanian A, Bakris GL, Black HR, Cushman WC, Green LA, Izzo JL Jr, et al. The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: The JNC 7 report. JAMA. 2003; 289(19): 2560-71.
  17. Mulatero P, Stowasser M, Loh KC, Fardella CE, Gordon RD, Mosso L, et al. Increased diagnosis of primary aldosteronism, including surgically correctable forms, in centers from five continents. J Clin Endocrinol Metab. 2004; 89:1045-50.
  18. Staessen JA, Wang JG, Thijs L. Cardiovascular protection and blood pressure reduction: A meta-analysis. Lancet. 2001; 358(9290): 1305-15.
  19. Turnbull F, Neal B, Algert C, Chalmers J, Chapman N, Cutler J, et al. Effects of different blood pressure-lowering regimens on major cardiovascular events in individuals with and without diabetes mellitus: Results of prospectively designed overviews of randomized trials.  Arch Intern Med. 2005; 165(12): 1410-9.
  20. Hill SR, Smith AJ.  First line medicines in the treatment of hypertension. Aust Prescr. 2005; 28: 34-7.
  21. Therapeutic Guidelines: Cardiovascular. Therapeutic Goods Administration; 2008.
  22. Guide to good prescribing. A practical manual [online]. Geneva: World Health Organization; 1994. Available from URL http://www.who.int/ medicines/ library/ par/ ggprescribing/ who-dap-94-11en.pdf
  23. Zillich AJ, Garg J, Basu S, Bakris GL, Carter BL. Thiazide diuretics, potassium and the development of diabetes: A quantitative review. Hypertension. 2006; 48(2): 219-24.
  24. Bangalore S, Parkar S, Grossman E, Messerli FH. A meta-analysis of 94,492 patients with hypertension treated with beta blockers to determine the risk of new-onset diabetes mellitus. Am J Cardiol. 2007; 100(8): 1254-62.
  25. Yusuf S, Teo KK, Pogue J, Dyal L, Copland I, Schumacher H, et al. Telmisartan, ramipril, or both in patients at high risk for vascular events. N Engl J Med. 2008: 358: 1547-59.
  26. Gupta AK, Dahlof B, Dobson J, Sever PS, Wedel H, Poulter NR. Determinants of new-onset diabetes among 19,257 hypertensive patients randomized in the Anglo-Scandinavian Cardiac Outcomes Trial – Blood Pressure Lowering Arm and the relative influence of antihypertensive medication. Diabetes Care. 2008: 31(5): 982-8.
  27. Australian Government: Department of Health and Ageing.  Pharmaceutical Benefits Schedule. [online] Department of Health and Ageing: PBS online, available: http://www.pbs.gov.au/html/healthpro/home
  28. The ALLHAT Collaborative Research Group. Major outcomes in high-risk hypertensive patients randomized to angiotensin-converting enzyme inhibitor or calcium channel blocker vs diuretic: The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). JAMA 2002; 288:2981.

Dates

Posted On: 21 February, 2006
Modified On: 18 September, 2014
Reviewed On: 2 September, 2009

 


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