Health-related Topics : High Blood Pressure (overview)

Dr. James Manos (MD)

October 21, 2015

Overview of high blood pressure

Note: in this text, the writer expresses his point of view. Some advice is empirical, so you should consult your family doctor beforehand.

Overview of high blood pressure (hypertension)

· Hypertension is a tremendous medical problem. It is defined as blood pressure (BP) equal to or more than 140 (systolic)/90(diastolic). 90 – 95% of the cases have an unknown cause, called ‘essential or primary hypertension,’ but alcohol and obesity may contribute. The remaining 5 – 10% have secondary hypertension, which has many causes, such as renal (kidney) disease (e.g., renal artery stenosis and glomerulonephritis (GN)), Cushing syndrome (e.g., from steroids), Conn’s syndrome, acromegaly, pheochromocytoma, hyperparathyroidism, hyperthyroidism, pregnancy, (gestational hypertension or eclampsia), coarctation of the aorta, etc.

· Hypertension is more common in men than premenopausal women and is more common in black people and low socioeconomic status.

· Check your blood pressure (BP) regularly, preferably 1 – 2 hours after waking up in the morning and at 6 p.m. BO is not steady but has a diurnal variation (a variation during the 24 h). I recommend measuring the morning and afternoon BP daily for 1 week and comparing the results. You should check your BP after resting for 10 to 15 minutes. The devices for measuring BP are called sphygmomanometers. The manual is more reliable than the digital (the less reliable form the digital is the wrist). The most reliable manual sphygmomanometer is the clinical mercury sphygmomanometer that most hospitals use. However, the manual aneroid sphygmomanometer with a cuff is preferred by most people to measure BP at home, as it is cheap and easy to use. You should not smoke or drink coffee before taking the BP. If the BP is equal to or above 140/80 mmHg or has a significant diurnal variation, you should consult your family doctor/ general practitioner (GP).

· If you have kidney, eye, or cardiovascular damage, you must consult your doctor if blood pressure is equal to or above 130/80 mmHg.

· In adults, normal blood pressure (BP) is for systolic BP 90 – 119 mmHg and for diastolic BP 60 – 79 mmHg. High normal BP (prehypertension) is for systolic BP 120 – 139 mmHg and for diastolic BP 80 – 89 mmHg. It is ‘borderline’ hypertension. Hypertension is systolic BP equal to or more than 140 mmHg and diastolic BP equal to or more than 90 mmHg.

· A systolic BP equal to or more than 180 mmHg and systolic BP equal to or more than 110 mmHg is a hypertensive emergency (malignant hypertension; hypertensive crisis) and should be treated medically, as it may be life-threatening as it may cause pulmonary edema, cerebrovascular accident (CVA; stroke), myocardial infarction (MI; heart attack), AKI (acute kidney injury; also known as acute renal failure (ARF)), hypertensive encephalopathy (brain disease) and aortic dissection.

· Gestational – hypertension is hypertension in pregnancy. It may lead to pre-eclampsia, a severe obstetric condition that may lead to eclampsia, a life-threatening condition for the mother and the embryo.

· People with diabetes mellitus with kidney disease (especially proteinuria such as nephrotic syndrome), cardiovascular disease or eye disease have a lower target BP for hypertension treatment.

· According to NICE (National Institute for Health & Care Excellence) in the UK, for people with diabetes mellitus, the target blood pressure is less than 130/80 mmHg for patients with kidney, eye, or cardiovascular damage. The target blood pressure is less than 140/80 mmHg for others.

· Three leading groups of heart experts have issued updated guidelines that set blood pressure goals for people with heart disease. The guidelines reinforce a target blood pressure of less than 140/90 mm Hg for those at risk for heart attack and stroke. The guidelines also set a goal of 130/80 mm Hg for those with heart disease who have already had a heart attack, stroke, or a mini-stroke (TIA; transient ischemic attack) or who have had a narrowing of their leg arteries or an abdominal aortic aneurysm (Reference: http://www.newsmax.com/Health/Health-News/blood-pressure-guidelines-heart/2015/03/31/id/635609/ ).

· The American Heart Association (AHA), American College of Cardiology (ACC), and American Society of Hypertension (ASH) issued new recommendations for treating hypertension in patients with coronary artery disease (CAD). The AHA/ACC/ASH guidelines recommend a target BP <130/80 mm Hg in some patients with CAD. However, lowering diastolic blood pressure (DBP) <60 mm Hg is not recommended in patients with CAD, especially those aged older than 60 years, due to the potential for increasing cardiovascular (CV) risk. The lower target may be appropriate for patients with a history of myocardial infarction, stroke, or transient ischemic attack and patients with specific risk equivalents for CAD, such as carotid artery disease, peripheral artery disease, and abdominal aortic aneurysm. There is a J-curve debate regarding the optimal BP level to achieve in diverse groups of patients. Over the past several years, considerable debate has been about using a target BP <130/80 mmHg in patients with higher cardiovascular (CV) risk. One of the critical factors in the debate is controversy over the J-curve phenomenon, in which CV risk can increase if BP levels are lowered excessively. If diastolic BP (DBP) levels are too low, the heart has less available oxygen during the rest phase of the heartbeat to initiate the next pulse, increasing cardiac workload, leading to cardiac ischemia, and increasing the risk of cardiac events. In other words, at some point, DBP is so low that the heart stops having to do less work and starts doing more work. The danger of lowering DBP below a certain level is thought to be the physiologic process behind the J-curve phenomenon. However, finding the inflection point of the J-curve—the optimal BP target—is a challenge because it varies among populations, and clinical trials have not yet discovered this ideal level in all populations.

· Systolic BP should not be lowered below 100, as cardiac output decreases, which may cause lightheadedness and fainting. This may be life-threatening for people with heart problems, including heart failure, and may cause heart ischemia in people with coronary heart disease (SHD).

· There is evidence that some younger people with prehypertension or ‘borderline hypertension’ have high cardiac output, an elevated heart rate, and normal peripheral resistance, termed borderline hyperkinetic hypertension. These individuals develop the typical features of established essential hypertension in later life as their cardiac output falls and peripheral resistance rises with age.

· Resistant hypertension is hypertension that remains above goal blood pressure despite using, at once, three antihypertensive medications belonging to different drug classes. Low adherence to treatment is an essential cause of resistant hypertension. Resistant hypertension may also represent the result of the chronic high activity of the autonomic nervous system. This is known as ‘neurogenic hypertension.’

· The peripheral resistance of the arteries rises with age. Thus, older people tend to have higher BP than younger people. The elderly, because of arteriosclerosis (hardening of the arteries), tend to have higher BP than younger people. They have increased arterial stiffness, reduced arterial compliance, and decreased elasticity.

· Arterial compliance, an index of the elasticity of large arteries such as the thoracic aorta. Arterial compliance is an important cardiovascular risk factor. Compliance diminishes with age and menopause. Arterial compliance is measured by ultrasound as a pressure (carotid artery) and volume (outflow into the aorta) relationship. Arterial Compliance is an action in which an artery yields to pressure or force without disruption. A measure of arterial compliance is used as an indication of arterial stiffening. An increase in age and systolic pressure is accompanied by decreased arterial compliance.

· Reference:

· http://www.ncbi.nlm.nih.gov/pubmed/10084567

· Arterial compliance mostly depends on arterial intrinsic elastic properties and is a determinant of the propagation speed of the pulse pressure wave. Decreased arterial compliance is responsible for increased incident pressure waves and the higher effect of reflected pressure waves. This increases systolic pressure and ventricular afterload and generates left ventricular hypertrophy (heart muscle enlargement associated with heart failure). Arterial structural changes that accompany the aging process result in a loss of distensibility and compliance. In primary (essential) and secondary hypertension, arterial compliance is reduced, and age-related structural changes of the arterial wall are accelerated. Calcium antagonists, as antihypertensive drugs, improve the distensibility and compliance of large and small arteries, contributing significantly to the improvement in managing essential and secondary hypertension (Reference: http://www.ncbi.nlm.nih.gov/pubmed/7512488 ).

· In the elderly, lowering the BP too much may decrease cardiac output and be dangerous if they have heart disease.

· Some home blood pressure monitors are not accurate. You may read the article at http://www.health.harvard.edu/blog/home-blood-pressure-monitors-arent-accurate-201410297494

· Unregulated hypertension is a silent killer, as it usually has no symptoms!

· Hypertension is the most important preventable risk factor for premature death!

· Hypertension may have serious complications such as increasing the risk for ischemic heart disease [IHD; atherosclerosis (hardening of the arteries) may cause myocardial Infraction (MI; heart attack)], cerebrovascular accident (CVA; stroke), peripheral vascular (arterial) disease (PAD), congestive heart failure (CHF), aortic aneurysm, hypertensive nephropathy [it may lead to ARF (acute renal failure) or chronic kidney disease (CKD)], pulmonary embolism, pulmonary edema from acute heart failure; and hypertensive retinopathy (retinal disease of the eye; it may lead to blinding). It may also predispose to (vascular) dementia.

· Treatment of hypertension includes life modification with diet (people with hypertension should avoid fat and salt), regular (aerobic) exercise, and antihypertensive drugs. Relaxation techniques (including Yoga) also help.

· Patients with hypertension should stop smoking, lose weight if overweight or obese, regularly exercise, decrease alcohol, caffeine, and salt intake, and increase fruit and vegetable intake.

· Hypertensive people should have a low-sodium diet and avoid salt. They should remember that almost all processed & restaurant food has salt (and sugar) added! This accounts for 75% of our sodium intake!

· Restricted salt intake applies to everyone, not only the hypertensive, as excessive salt increases blood pressure.

· A low-sodium diet is especially crucial for salt-sensitive hypertension.

· Although the pathogenesis of salt-sensitive hypertension is heterogeneous, it is attributable to an impaired renal capacity to excrete sodium (Reference: http://www.ncbi.nlm.nih.gov/pubmed/22713140 ).

· People should eat less than half a teaspoon of salt daily. However, they should keep in mind that salt (and sugar) is added to all processed & restaurant food.

· Primary hypertension (formerly called "essential" hypertension) is seen primarily in societies with average sodium intakes above 100 meq/day (2.3 g sodium); however, it is rare in societies with average sodium intakes of less than 50 meq/day (1.2 g sodium). Reducing salt intake from 170 to 100 meq/day lowers the mean blood pressure (BP) in normotensive (with normal blood pressure) adults by approximately 2/1 mmHg and in hypertensive adults by 5/3 mmHg. However, over the course of 30 years, the fall in BP may be more significant, in part because salt restriction minimizes the expected rise in BP associated with aging (because of arteriosclerosis (hardening of the arteries)) (Reference (Retrieved: October 11, 2015): http://www.uptodate.com/contents/salt-intake-salt-restriction-and-primary-essential-hypertension ).

· The American Heart Association recommends consuming less than 1,500 mg of sodium daily. 1/4 teaspoon of salt has 575 mg sodium; 1/2 teaspoon salt contains 1,150 mg sodium; 3/4 teaspoon salt contains 1,725 mg sodium, and one teaspoon has 2,300 mg sodium.

· Table salt combines two minerals: sodium (Na⁺) and chloride (Cl^-). Table salt is approximately 40% sodium and 60% chloride by weight. About 90% of Americans’ sodium intake comes from sodium chloride.

· You can find the amount of sodium in packaged food sold in stores by looking at the Nutrition Facts label. The amount of sodium per serving is listed in milligrams (mg). The sodium content of packaged and prepared foods can vary widely. Check the labels to help you achieve the American Heart Association’s recommendation of 1,500 mg a day.

· 90% of American adults are expected to develop high blood pressure in their lifetimes, and overeating sodium is strongly linked to the development of high blood pressure. If the U.S. population moved to an average intake of 1,500 mg/day sodium from its current level, it could result in a 25.6% overall decrease in blood pressure and an estimated $26.2 billion in health care savings. Achieving this goal would reduce deaths from CVD by anywhere from 500,000 to nearly 1.2 million over the next 10 years (Reference: http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyEating/About-Sodium-Salt_UCM_463416_Article.jsp and http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyEating/Frequently-Asked-Questions-FAQs-About-Sodium_UCM_306840_Article.jsp ).

· For tracking the sodium in food, you may check the articles of the American Heart Association (AHA): http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyEating/How-to-Track-Your-Sodium_UCM_449547_Article.jsp and http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyEating/About-Sodium-Salt_UCM_463416_Article.jsp

· The recommendation for less than 1,500 mg of sodium daily does not apply to people who lose significant amounts of sodium in sweat, such as competitive athletes and workers exposed to extreme heat stress (for example, foundry workers and firefighters), or to those directed otherwise by their healthcare provider (Reference: http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyEating/Frequently-Asked-Questions-FAQs-About-Sodium_UCM_306840_Article.jsp ).

· During a hot day in summer or strenuous physical exercise, we need extra salt, water, and carbohydrates (sugar) to avoid dehydration and electrolyte imbalance that may be life-threatening. In 2003, 14,802 people – most of them elderly – died in a heatwave in France, as they avoided replacing salt and other electrolytes and water during the heat, and died from heatstroke and dehydration, as well as thrombosis that was predisposed by dehydration.

· Salt also has iodine as an additive necessary for the thyroid gland. Its deficiency in children may cause cretinism, a severe mental disease. We can’t live with zero salt. However, as mentioned above, salt is added to almost all processed food.

· High potassium diet as a method for treating hypertension is contraindicated in patients with kidney failure and those who take potassium-sparing diuretics, as it may cause hyperkalemia (high blood potassium) that may lead to a severe heart arrhythmia. Thus, a high-potassium diet has contraindications & adverse effects.

· A meta-analysis concluded that high–quality evidence shows that increased potassium intake reduces blood pressure in people with hypertension and has no adverse effect on blood lipid concentrations, catecholamine concentrations, or renal function in adults. Higher potassium intake was associated with a 24% lower risk of stroke (moderate-quality evidence). These results suggest that increased potassium intake potentially benefits most people without impaired renal handling of potassium to prevent and control elevated blood pressure and stroke (Reference: http://www.bmj.com/content/346/bmj.f1378 ).

· The DASH diet (dietary approaches to stop hypertension) is recommended by the USA Department of Agriculture (USDA) and is rich in fruits, vegetables, whole grains, and low-fat dairy foods; it includes meat, fish, poultry, nuts, and beans; and is limited in sugar-sweetened foods and beverages, red meat, and added fats. You may check the article on https://en.wikipedia.org/wiki/DASH_diet

· Biofeedback, meditation, yoga, and other relaxation techniques may help.

· If indicated, statins and aspirin are used to prevent the risk of cardiovascular and cerebrovascular disease and prevent heart attack and stroke.

Antihypertensive medications

· First-Line medications for hypertension include thiazide diuretics, calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors, and angiotensin receptor blockers (ARBs). These drugs may be used alone or in combination. Most people with hypertension require more than one medication to control their hypertension.

· Patients taking drugs for heart problems (including blood pressure-lowering drugs and drugs for heart arrhythmia) should never stop their medication abruptly, as it may cause a rebound increase in the BP that may lead to stroke or pulmonary edema from acute heart failure. Generally, people taking medications, including antibiotics, corticosteroids, circulation, and psychiatric drugs, should not stop taking them abruptly without consulting their doctor, as life-threatening medical issues may occur.

The antihypertensive drugs ACE inhibitors & ARBs

Angiotensin-converting enzyme (ACE) Inhibitors

· Angiotensin-converting enzyme inhibitors (ACE inhibitors, e.g., perindopril, captopril, enalapril, ramipril & lisinopril).

· They are a group of pharmaceuticals that modulate the renin-angiotensin-aldosterone system. These substances inhibit the Angiotensin-converting enzyme (ACE) and thus block the conversion of angiotensin I (AT-I) to angiotensin II (AT-II), causing vasodilation, reducing the secretion of antidiuretic hormone (ADH, vasopressin), and reduces production and secretion of aldosterone, among other actions. The combined effect reduces blood pressure.

· They mainly treat hypertension, diabetic nephropathy, and congestive heart failure.

· Adverse effects include hyperkalemia (high blood potassium), angioedema, and persistent dry cough.

Angiotensin receptor blockers (ARBs)

· Angiotensin receptor blockers (ARBs, e.g., valsartan & losartan) are a group of pharmaceuticals that modulate the renin-angiotensin-aldosterone system.

· These substances are AT₁-receptor antagonists, i.e., they block the activation of angiotensin II AT1 receptors, causing vasodilation, reducing the secretion of antidiuretic hormone (ADH, vasopressin) and reducing production and secretion of aldosterone, among other actions. The combined effect reduces blood pressure.

· Their primary uses are in treating hypertension, diabetic nephropathy, and congestive heart failure.

· ARBs are used primarily for treating hypertension, where the patient is intolerant of ACE inhibitor therapy due to a dry cough.

· Adverse effects include hyperkalemia (high blood potassium; it may cause a severe heart arrhythmia).

· They may also increase longevity!

Methods of attenuation of the reduction of arterial compliance

Natural ways

· Exercise (aerobic training) such as swimming

· Tai Chi (an internal Chinese martial art)

· Medications

· Rosiglitazone (a drug for diabetes mellitus type 2)

· Combination of amlodipine (a drug for hypertension) & atorvastatin (a statin; a cholesterol-lowering agent)

· Combination of Angiotensin-Converting Enzyme inhibitor (ACEI) and the diuretics hydrochlorothiazide & amiloride (ACEI & the diuretics are used for hypertension and heart failure)

· Pravastatin (a statin; a cholesterol-lowering agent)

· ALT-711 (a novel non-enzymatic breaker of advanced glycation end-product crosslinks)

· The vitamins folic acid (folate), vitamin B6 (pyridoxine) & vitamin B12 decrease homocysteine levels that harm the heart.

· Calcium antagonists, as antihypertensive drugs, improve the distensibility and compliance of large and small arteries, contributing significantly to the improvement in managing essential and secondary hypertension (Reference: http://www.ncbi.nlm.nih.gov/pubmed/7512488 ).

Thanks for reading!

Reference – Bibliography

· Longo D.L., Fauci A.S., Kasper D.L., Hauser S.L., Jameson J.L., Loscalzo J.L., Harrison’s Manual of Medicine, 18^th edition, McGraw–Hill, 2013.

· Longmore M., Wilkinson I.B., Davidson E.H., Foulkes A., Mafi A.R., Oxford Handbook of Clinical Medicine, 8^th edition, Oxford University Press, 2010.

· Ahmed N., Clinical Biochemistry, Oxford University Press, 2010.

· Kasper D.L., Braunwald E., Fauci A.S., Hauser S.L., Longo D.L., Jameson J.L., Harrison’s Manual of Medicine, McGraw–Hill, 16th edition, 2005.

· Simon C., Everitt H., Kendrick T., Oxford Handbook of General Practice, Oxford Medical Publications, 2nd edition, 2005.

· Longmore M., Wilkinson I., Turmezei T., Kay Cheung C., Oxford Handbook of Clinical Medicine, Oxford Medical Publications, 7th edition, 2008.

· Collier J., Longmore M., Brinsden M., Oxford Handbook of Clinical Specialties, Oxford Medical Publications, 7th edition, 2006.

· Stone C.K., Humphries R.L., Current Diagnosis and Treatment in Emergency Medicine, McGraw–Hill LANGE, 6th edition, 2008.

Reference - Links (Retrieved October 11, 2015)