Hypertension
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Introduction
Hypertension, or high blood pressure, is a very common chronic condition, affecting 20-25% of adults. It is also very serious, being one of the leading causes of cardiovascular disease. It is estimated to be responsible for over 7 million deaths worldwide annually (Perkovic et al, 2009), or 13% of deaths worldwide (ref).
The lifetime risk for hypertension among middle-aged, normotensive adults is around 90% (Vasan et al, 2002). In Ontario, age- and sex-adjusted prevalence has increased 60% from 1995 to 2005, while incidence increased 26% (Tu et al, 2008).
Hypertension is diagnosed with blood pressure readings over 140 systolic or 90 diastolic on at least three occasions.
Normal blood pressure is less than 120 systolic and 80 diastolic, while prehypertension is between 120-139 systolic and 80-89 diastolic.
The JNC-V (Pogue et al, 1996) criteria ranks hypertension as:
- Stage 1 (mild) 140-159 / 90-99
- Stage 2 (moderate) 160-179 / 100-109
- Stage 3 (severe) 180-209 / 110-119
- Stage 4 (very severe) >=210 / >=120
The Case of...
a simple case introducing clincial presentation and calling for a differential diagnosis to get students thinking.
Causes and Risk Factors
- essential hypertension
- secondary hypertension
- apparent hypertension
Essential Hypertension
A specific cause of hypertension is found in 10-15% of patients. The other 85-90% is termed essential, meaning no other medical reason is present. Contributing factors to essential hypertension are thought to include:
- high dietary intake of salt (>2.5 g/day), but only 40-50% of people are salt sensitive
- stress
- genetics : black people have increased risk
- age
- sex - males are more likely
- smoking
- sedentary lifestyle
- diabetes mellitus
- alcohol consumption
Pathophysiology
Peripheral resistance is increased by the sympathetic nervous system, hormines such as aldosterone, thyroid hormone, and insulin, as well as paracrine signals including prostaglandins, endothelin, and nitric oxide.
A reduced baroreceptor response also occurs. There is increasing evidence that essential hypertension may be a primary defect in sodium excretion by the kidney, leading to increased intravascular volume (ref).
Hypertension induces structural changes to the vasculature through hypertrophy of resistance vessels. Endothelial dysfunction includes reduced nitric oxide and increased endothelin.
It is speculated that excess insulin, as occurs in insulin resistance, may play a role in sodium retention, blood volume expansion, excess norephinephrine production, and smooth muscle proliferation. Hyperglycemia itself also leads to endothelial cell dysfunction, adding to the doubled rates of hypertension in people with diabetes.
Systolic pressure rises with age, though the diastolic does not. The elderly often show isolated systolic hypoertension.
Signs and Symptoms
- history
- physical exam
History
As over 40% of people with hypertension do not know it (Joffres et al, 1997), it is termed 'the silent killer'. However, people may have an occipital headache on awakening, or can complain of vision changes.
Sudden onset would suggest renovascular hypertension.
History should be focused on symptoms of organ damage caused by hypertension:
- cardiovascular disease
- stroke/TIA
- peripheral artery disease
- kidney disease
- diabetes
- snoring, sleep pauses, suggesting sleep apnea
Vascular disease can also point towards renovascular causes for hypertension.
family history
- hypertension
- premature CVD
- stroke
- diabetes
- dyslipidemia
medications
- results and side effects of previous therapy
- commonly prescribed/OTC/illegal medications which can raise bp
social history
- education, work conditions
- finances
- family/friend dynamics
- other sources of stress
- cigarettes, alcohol, other drugs
- diet: sodium and fats
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
Lab investigations for everyone with hypertension include:
- urinalysis
- CBC
- electrolytes
- BUN and creatinine
- fasting lipid profile
- fasting blood glucose
- TSH
Other tests should be done for specific patient subgroups, and include:
- diabetes or renal disease: urinary protein excretion
- plasma aldosterone and renin (endocrine)
- 24 hour urine for catecholamines (phaeochromocytoma)
Differential Diagnosis
Treatment Options
Intensive control of blood pressure, lipid levels, and hyperglycemia can save the health care system money while preventing death and disability GET STATS (CDC, 2002). There has been remarkable improvement in hypertension control in recent years, with rates ranging from 25-82% (Mohan and Campbell, 2008).
- lifestyle
- pharmacological
- patient motivation
- resistant hypertension
Lifestyle
Lifestyle measures are incredibly important in preventing and reducing hypertension. These include:
- reduce foods with added sodium: under 2300 mg/day DASH diet
- teach about reading labels
- increased potassium intake
- physical activity
- weight loss
- alcohol reduction
- smoking cessation
- stress reduction
Consequences and Course
Hypertension is a key contributor to disease in society. Nearly 2/3 of strokes and 1/2 of ischemic heart disease is directly attributable to it (Lawes et al, 2006).
- cardiovascular
- renal
- other
- malignant hypertension
Cardiovascular
Even mild hypertension, slightly above 140/90, if sufficiently prolonged, increases the demands of the heart, which adapts with concentric hypertrophy. This can lead to myocardial dysfunction, ischemic heart disease, atrial fibrillation, heart failure, or sudden death.
Cerebral ischemia or hemorrhagic stroke is most commonly caused by hypertension.
Other vascular conditions can include aneurysm, aortic dissection, or peripheral artery disease.
Even a 2 mmgHg reduction can lead to substantial reductions in mortality (ref).
Additional Resources
- CDC Diabetes Cost-Effectiveness Group. 2002. Cost-effectiveness of intensive glycemic control, intensified hypertension control, and serum cholesterol level reduction for type 2 diabetes. JAMA. 287:2542-51.
- Feldman RD et al. 2009. A simplified approach to the treatment of uncomplicated hypertension: a cluster randomized, controlled trial. Hypertension. 53(4):646-53.
- Lawes et al. 2006. Blood pressure and the global burden of disease 2000. Part II: estimates of attributable burden. Journal of Hypertension. 24:423-30.
- Mohan S and Campbell NRC. 2008. Hypertension management in Canada: good news, but important challenges remain. CMAJ. 178(11):1458-60.
- Perkovic V et al. 2007. The Burden of Blood Pressure-Related Disease - A Neglected Priority for Global Health. Hypertension. 50:991.
- Pogue VA, Ellis C, Michel J, Francis CK. 1996. New Staging System of the Fifth Joint National Committee Report on the Detection, Evaluation, and Treatment of High Blood Pressure (JNC-V) Alters Assessment of the Severity and Treatment of Hypertension. Hypertension. 28:713-718
- Tu et al. 2008. Prevalence and incidence of hypertension from 1995 to 2005: a population-based study. CMAJ. 178:1429-35.
- Vasan RS et al. 2002. Residual Lifetime Risk for Developing Hypertension in Middle-aged Women and Men. JAMA. 287:1003-10.
- http://www.hypertension.ca
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