\r\n| Hypertension<\/td>\r\n | 140 or higher<\/td>\r\n | 90 or higher<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\nHigh blood pressure is classified as either primary or secondary high blood pressure. At least 90% of cases are primary high blood pressure, which is caused by some combination of genetic and lifestyle factors. Numerous genes have been identified as having small effects on blood pressure. Lifestyle factors that increase the risk of high blood pressure include excess dietary salt and alcohol consumption, as well as the risk factors for cardiovascular disease listed above. Secondary high blood pressure, which makes up the remaining ten per cent of cases of hypertension, is attributable to a particular identifiable cause, such as chronic kidney disease or an endocrine disorder (such as Cushing\u2019s disease).\r\n\r\nTreating hypertension is important for reducing the risk of all types of cardiovascular disease, especially [pb_glossary id=\"3103\"]stroke[\/pb_glossary]. These and other complications of persistent high blood pressure are shown in Figure 14.6.2. Lifestyle changes, such as reducing salt intake and adopting a healthier diet may be all that's needed to lower blood pressure to the normal range. In many cases, however, medications are also required. The majority of people with high blood pressure have to take more than one medication to fully control their hypertension.\r\n\r\n[caption id=\"attachment_4507\" align=\"aligncenter\" width=\"742\"]![\"14.6.2\"](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Main_complications_of_persistent_high_blood_pressure.svg_-2.png\") Figure 14.6.2 If high blood pressure is not brought under control, it can eventually have many detrimental effects.<\/em>[\/caption]\r\nAtherosclerosis<\/h2>\r\n[pb_glossary id=\"4508\"]Atherosclerosis[\/pb_glossary]<\/strong> is a condition in which artery walls thicken and stiffen as a result of the buildup of plaques inside the arteries, similarly to minerals collecting in plumbing that carries hard water. Plaques consist of leukocytes, cholesterol, and other fats. Typically, there is also a proliferation of smooth muscle cells that make the plaque fibrous, as well as fatty. Over time, the plaques may harden with the addition of calcium crystals. This reduces the elasticity of the artery walls. As plaques increase in size, the artery walls dilate to compensate so blood flow is not affected. Eventually, however, the lumen of the arteries is likely to become so narrowed by plaque buildup that blood flow is reduced, or even blocked entirely. Figure 14.6.3 illustrates the formation of a plaque in a coronary artery.\r\n\r\n[caption id=\"attachment_4509\" align=\"aligncenter\" width=\"599\"]![\"14.6.3](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Coronary_heart_disease-atherosclerosis-2.png\") Figure 14.6.3 A plaque in a coronary artery may reduce blood flow to cardiac muscle cells.<\/em>[\/caption]\r\n\r\nIn most people, plaques start to form in arteries during\u00a0childhood, and progress throughout life. Individuals may develop just a few plaques, or dozens of them. Plaques typically remain asymptomatic for decades. Signs and symptoms appear only after there is severe narrowing ([pb_glossary id=\"4510\"]stenosis[\/pb_glossary]) or complete blockage of arteries. As plaques increase in size and interfere with blood flow, they commonly lead to the formation of blood clots. These clots may plug arteries at the site of the plaque or travel elsewhere in the\u00a0circulation. Sometimes, plaques rupture or become detached from an arterial wall and become lodged in a smaller, downstream artery. Blockage of arteries by plaques or clots may cause a [pb_glossary id=\"4368\"]heart attack[\/pb_glossary], [pb_glossary id=\"3103\"]stroke[\/pb_glossary], or other potentially life-threatening cardiovascular event. If blood flow to the\u00a0kidneys\u00a0is affected, it may lead to [pb_glossary id=\"4511\"]chronic kidney disease[\/pb_glossary].\r\n\r\nThe process in which plaques form is not yet fully understood, but it is thought that it begins when low-density lipoproteins ([pb_glossary id=\"4512\"]LDL[\/pb_glossary]s) accumulate inside endothelial cells in artery walls, causing inflammation. The inflammation attracts leukocytes that start to form a plaque. Continued inflammation and a cascade of other immune responses cause the plaque to keep growing. Risk factors for the development of atherosclerosis include [pb_glossary id=\"4231\"]hypertension[\/pb_glossary], high cholesterol (especially LDL cholesterol), [pb_glossary id=\"2969\"]diabetes[\/pb_glossary], and smoking. The chance of developing atherosclerosis also increases with age, male sex, and a family history of cardiovascular disease.\r\n\r\nTreatment of atherosclerosis often includes both lifestyle changes and medications to lower cholesterol, control blood pressure, and reduce the risk of blood clot formation. In extreme cases, or when other treatments are inadequate, surgery may be recommended. Surgery may involve the placement of stents in arteries to keep them open and improve blood flow, or the use of grafts to divert blood flow around blocked arteries.\r\n\r\n Coronary Artery Disease<\/h1>\r\n<\/div>\r\n[pb_glossary id=\"4513\"]Coronary artery disease[\/pb_glossary]<\/strong>\u00a0is a group of diseases that result from atherosclerosis of coronary arteries. Treatment of the diseases mainly involves treating the underlying atherosclerosis. Two of the most common coronary artery diseases are angina and myocardial infarction.\r\nAngina<\/h2>\r\n[caption id=\"attachment_4516\" align=\"alignright\" width=\"554\"]![\"14.6.4](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Blausen_0022_Angina-1-2.png\") Figure 14.6.4 Angina is pain in the chest due to reduced blood flow in coronary arteries, so the heart muscle does not receive adequate oxygen.<\/em>[\/caption]\r\n\r\n[pb_glossary id=\"4514\"]Angina[\/pb_glossary]<\/strong> is chest pain or pressure that occurs when heart muscle cells do not receive adequate blood flow and become starved of oxygen (a condition called [pb_glossary id=\"4515\"]ischemia[\/pb_glossary]). This is illustrated in Figure 14.6.4. There may also be pain in the back, neck, shoulders, or jaw \u2014 and in some cases, the pain may be accompanied by shortness of breath, sweating, or nausea. The main goals of angina treatment are to relieve the symptoms and slow the progression of the underlying atherosclerosis.\r\n\r\nAngina may be classified as either stable angina or unstable angina:\r\n\r\n \t- [pb_glossary id=\"4517\"]Stable angina[\/pb_glossary]<\/strong>\u00a0is angina in which pain is precipitated by exertion (from brisk walking or running, for example) and improves quickly with rest or the administration of nitroglycerin, which dilates coronary arteries and improves blood flow. Stable angina may develop into unstable angina.<\/li>\r\n \t
- [pb_glossary id=\"4518\"]Unstable angina[\/pb_glossary]<\/strong>\u00a0is angina in which pain occurs during rest, lasts more than 15 minutes, and is of new onset. This type of angina is more dangerous, and may be a sign of an imminent heart attack. It requires urgent medical attention.<\/li>\r\n<\/ul>\r\n
Myocardial Infarction<\/h2>\r\nA\u00a0[pb_glossary id=\"4519\"]myocardial infarction[\/pb_glossary] (MI)<\/strong>, commonly known as a heart attack, occurs when blood flow stops to part of the heart, causing damage to the heart muscle and death of myocardial cells. As shown in Figure 14.6.5, an MI usually occurs because of complete blockage of a coronary artery, often due to a blood clot or the rupture of a plaque. An MI typically causes chest pain and pressure, among other possible symptoms, but at least one quarter of MIs do not cause any symptoms.\r\n\r\n[caption id=\"attachment_4520\" align=\"aligncenter\" width=\"400\"]![\"14.6.5](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Heart_attack-NIH-2.gif\") Figure 14.6.5 A myocardial infarction occurs when cardiac muscle cells die due to blockage of a coronary artery.<\/em>[\/caption]\r\n\r\nIn the worst case, an MI may cause sudden death. Even if the patient survives, an MI often causes permanent damage to the heart. This puts the heart at risk of heart [pb_glossary id=\"4521\"]arrhythmias[\/pb_glossary], [pb_glossary id=\"4219\"]heart failure[\/pb_glossary], and [pb_glossary id=\"4522\"]cardiac arrest[\/pb_glossary].\r\n\r\n \t- Heart [pb_glossary id=\"4521\"]arrhythmias[\/pb_glossary]<\/strong>\u00a0are abnormal heart rhythms, which are potentially life threatening. Heart arrhythmias often can be interrupted with a cardiac defibrillator, which delivers an electrical shock to the heart, in effect \u201crebooting\u201d it.<\/li>\r\n \t
- [pb_glossary id=\"4219\"]Heart failure[\/pb_glossary]<\/strong>\u00a0occurs when the pumping action of the heart is impaired, causing tissues\u00a0to get inadequate oxygen. This is a chronic condition that tends to get worse over time, although it can be managed with medications.<\/li>\r\n \t
- [pb_glossary id=\"4522\"]Cardiac arrest[\/pb_glossary]<\/strong>\u00a0occurs when the heart no longer pumps blood or pumps blood so poorly that vital organs can no longer function. This is a medical emergency\u00a0that requires\u00a0immediate intervention.<\/li>\r\n<\/ul>\r\n
\r\n Other Cardiovascular Diseases<\/h1>\r\n<\/div>\r\nHypertension and atherosclerosis often cause other cardiovascular diseases, including stroke and peripheral artery disease.\r\nStroke<\/h2>\r\nA\u00a0[pb_glossary id=\"3103\"]stroke[\/pb_glossary],<\/strong> also known as a cerebrovascular accident or brain attack, occurs when blocked or broken arteries cause brain cells to die. There are two main types of stroke, both of which are illustrated below: ischemic stroke and hemorrhagic stroke (Figures 14.6.6 and 14.6.7).\r\n\r\n \t- An\u00a0[pb_glossary id=\"4523\"]ischemic stroke[\/pb_glossary]<\/strong> occurs when an blood clot breaks off from a plaque, or forms in the heart because of arrhythmia and travels to the brain, where it becomes lodged in an artery. This blocks blood flow to the part of the brain that is served by arteries downstream from the blockage. Lack of oxygen causes the death of brain cells. Treatment with a clot-busting drug within a few hours of the stroke may prevent permanent damage. Almost 90% of strokes are ischemic strokes.<\/li>\r\n \t
- A\u00a0[pb_glossary id=\"4524\"]hemorrhagic stroke[\/pb_glossary]<\/strong> occurs when an artery in the brain ruptures and causes bleeding in the brain. This deprives downstream tissues of adequate blood flow, and also puts pressure on brain tissue. Both factors can lead to the death of brain cells. Surgery to temporarily open the cranium may be required to relieve the pressure. Only about ten per cent of strokes are hemorrhagic strokes, but they are more likely to be fatal than ischemic strokes.<\/li>\r\n<\/ol>\r\n[caption id=\"attachment_4525\" align=\"aligncenter\" width=\"475\"]
![\"14.6.6](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Stroke_ischemic-2.jpg\") Figure 14.6.6 In an ischemic stroke, brain cells die due to a blocked artery in the brain.<\/em>[\/caption]\r\n\r\n[caption id=\"attachment_4526\" align=\"aligncenter\" width=\"475\"]![\"14.6.7](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Stroke_hemorrhagic-2.jpg\") Figure 14.6.7 In a hemorrhagic stroke, brain cells die due to bleeding in the brain. In the example shown here, bleeding occurs when a cerebral artery aneurysm (localized bulge in the wall of a blood vessel) breaks open.<\/em>[\/caption]\r\n\r\nIn both types of stroke, the part of the brain that is damaged loses is ability to function normally. Signs and symptoms of stroke may include an inability to move, feel, or see on one side of the body; problems understanding speech or difficulty speaking; memory problems; confusion; and dizziness. Hemorrhagic strokes may also cause a severe headache. The symptoms of stroke usually occur within seconds or minutes of the brain injury. Depending on the severity of the stroke and how quickly treatment is provided, the symptoms may be temporary or permanent. If the symptoms of a stroke go away on their own in less than an hour or two, the stroke is called a transient ischemic attack. Stroke is the leading cause of disability in the United States, but rehabilitation with physical, occupational, speech, or other types of therapy may significantly improve functioning.\r\n\r\nThe main risk factor for stroke is high blood pressure.\u00a0Keeping blood pressure within the normal range, whether with lifestyle changes or medications, is the best way to reduce the risk of stroke. Another possible cause of stroke is the use of illicit drugs, such as amphetamines or cocaine. Having had a stroke in the past also greatly increases one\u2019s risk of future strokes. Men are more likely than women to have strokes.\r\nPeripheral Artery Disease<\/h2>\r\n[caption id=\"attachment_4528\" align=\"alignright\" width=\"400\"]![\"14.6.8](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Peripheral_Arterial_Disease-2.gif\") Figure 14.6.8 Peripheral artery disease typically causes pain and other symptoms, because of decreased blood flow in the leg or other areas of the body served by peripheral arteries.<\/em>[\/caption]\r\n\r\n[pb_glossary id=\"4527\"]Peripheral artery disease[\/pb_glossary] (PAD)<\/strong>\u00a0is a narrowing of the arteries other than those that supply the heart or brain, due to [pb_glossary id=\"4508\"]atherosclerosis[\/pb_glossary]. Figure 14.6.8 shows how PAD occurs. PAD most commonly affects the legs, but other arteries may also be involved. The classic symptom is leg pain when walking, which usually resolves with rest. This symptom is known as intermittent claudication. Other symptoms may include skin ulcers, bluish skin, cold skin, or poor nail and hair growth in the affected leg(s). Up to half of all cases of PAD, however, do not have any symptoms.\r\n\r\nThe main risk factor for PAD is smoking. Other risk factors include diabetes, high blood pressure, and high blood cholesterol. The underlying mechanism is usually atherosclerosis. PAD is typically diagnosed when blood pressure readings taken at the ankle are lower than blood pressure readings taken at the upper arm. It is important to diagnose PAD and treat the underlying atherosclerosis, because people with this disorder have a four to five times higher risk of myocardial infarction or stroke. Surgery to expand the affected arteries or to graft vessels in order to bypass blockages may be recommended in some cases.\r\n\r\n Feature: My\u00a0Human Body<\/h1>\r\n<\/div>\r\nYou read in this section about the many dangers of [pb_glossary id=\"4231\"]hypertension[\/pb_glossary]. Do you know if you have hypertension? The only way to know for sure is to have your blood pressure measured. Measuring blood pressure is quick and painless, but several measurements are needed to accurately diagnose hypertension. Some people have what is called \u201cwhite coat disease.\u201d Their blood pressure rises just because they are being examined by a physician (in a white coat). Blood pressure also fluctuates from time to time due to factors such as hydration, stress, and time of day. Repeatedly measuring and recording your own blood pressure at home can provide your doctor with valuable diagnostic data. Digital blood pressure monitors for home use, like the one in Figure 14.6.9, are relatively inexpensive, easy to use, and available at most pharmacies.\r\n\r\n[caption id=\"attachment_4529\" align=\"alignleft\" width=\"291\"]![\"14.6.9](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Wrist-style-blood-pressure-monitor-2.png\") Figure 14.6.9 This personal blood pressure monitor is worn on the wrist.<\/em>[\/caption]\r\n\r\nIf you\u00a0do<\/em>\u00a0have high blood pressure, lifestyle changes with or without medications can usually bring it under control. A commonly recommended lifestyle change is the adoption of a healthier eating plan, such as the DASH (\u201cDietary Approaches to Stop Hypertension<\/a>\u201d) diet. This diet was developed specifically to lower blood pressure without medication. Numerous studies have found the DASH diet to be effective at reducing not only high blood pressure, but also the risk of coronary artery disease, heart failure, stoke, some kinds of cancer, and diabetes. This diet has also been found effective for weight loss. The DASH diet includes whole grains, fruits and vegetables, low-fat or nonfat dairy, lean meats, fish and poultry, beans, nuts, and seeds.\r\n |
![\"14.6.1](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2019\/06\/Burger-by-chad-montano-GFCYhoRe48-unsplash-scaled-3.jpg\")
Figure 14.6.1 Why does fat taste so good?<\/em>[\/caption]\r\n\r\n![Main_complications_of_persistent_high_blood_pressure.svg<\/a> by](\"https:\/\/commons.wikimedia.org\/wiki\/File:Main_complications_of_persistent_high_blood_pressure.svg\"){kind=link}
![Coronary_heart_disease-atherosclerosis<\/a> by](\"https:\/\/commons.wikimedia.org\/wiki\/File:Coronary_heart_disease-atherosclerosis.PNG\"){kind=link}
![Blausen_0022_Angina (1)<\/a> by BruceBlaus on Wikimedia Commons is used under a](\"https:\/\/commons.wikimedia.org\/wiki\/File:Blausen_0022_Angina.png\"){kind=link}
![Heart_attack-NIH<\/a> by](\"https:\/\/commons.wikimedia.org\/wiki\/File:Heart_attack-NIH.gif\"){kind=link}
![Stroke_ischemic<\/a> by](\"https:\/\/commons.wikimedia.org\/wiki\/File:Stroke_ischemic.jpg\"){kind=link}
![Stroke_hemorrhagic<\/a> by](\"https:\/\/commons.wikimedia.org\/wiki\/File:Stroke_hemorrhagic.jpg\"){kind=link}
![Peripheral_Arterial_Disease<\/a> by](\"https:\/\/commons.wikimedia.org\/wiki\/File:Peripheral_Arterial_Disease.gif\"){kind=link}
![Wrist-style-blood-pressure-monitor<\/a> by](\"https:\/\/commons.wikimedia.org\/wiki\/File:Wrist-style-blood-pressure-monitor.png\"){kind=link}