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Hypertension
 

Hypertension

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Hypertension. Blood pressure levels are a function of cardiac output multiplied by peripheral resistance

Hypertension. Blood pressure levels are a function of cardiac output multiplied by peripheral resistance

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  • Primary hypertension accounts for approximately 90-95% of patients diagnosed with hypertension. Unlike secondary hypertension , there is no known cause of primary hypertension. Despite many years of active research, there is no unifying hypothesis to account for the pathogenesis of primary hypertension. There is a natural progression of this disease that suggests early elevations in blood volume and cardiac output might initiate subsequent changes in the systemic vasculature (increased resistance ). This has suggested to some researchers that a basic underlying defect in many hypertensive patients is an inability of the kidneys to adequately handle sodium. Increased sodium retention could then account for the increase in blood volume.  In chronic, long-standing hypertension, blood volume and cardiac output are often normal, therefore the hypertension is sustained by an elevation in systemic vascular resistance rather than by an increase in cardiac output. This increased resistance is caused by a thickening of the walls of resistance vessels and by a reduction in lumen diameters. There is also evidence for increased vascular tone . This could be mediated by enhanced sympathetic activity or by increased circulating levels of angiotensin II . In recent years, considerable evidence has suggested that changes in vascular endothelial function may cause the increase in vascular tone
  • Hypertension means high blood pressure. High blood pressure is an increased pressure in your blood vessels, and therefore there is less space for your blood to travel through It can be caused by many factors such as stress, high cholesterol, and inactivity. It is classified into mild, moderate, and severe hypertension. If you have mild, moderate, or severe hypertension, you have an increased risk of having a heart attack or a stroke .
  • The diameter of the blood vessel affects blood flow. When the diameter is decreased, as in CHD, resistance and blood pressure increases. Two classes of of hypertension.   In 90-95% of patients presenting with hypertension, the cause is unknown.  This condition is called primary (or essential) hypertension .  The remaining 5-10% of hypertensive patients have hypertension that results secondarily from renal disease, endocrine disorders, or other identifiable causes. This form of hypertension is called secondary hypertension . Hemodynamic basis of hypertension.   Regardless of the origin of hypertension, the actual increase in arterial blood pressure is caused by either an increase in systemic vascular resistance (SVR) or an increase in cardiac output (CO). The former is determined by the vascular tone (i.e., state of constriction) of systemic resistance vessels, whereas the latter is determined by heart rate and stroke volume .  Therefore, in order to understand how arterial blood pressure can become elevated, it is necessary to understand the mechanisms that regulate both SVR and CO. 
  • In most forms of hypertension, the hypertensive state is maintained by an elevation in blood volume , which in turn increases cardiac output by the Frank-Starling relationship .  Diuretic drugs , which enhance the removal of sodium and water by the kidneys and thereby decrease blood volume, are very effective in the treatment of hypertension. Hypertension is also commonly treated with drugs that decrease cardiac output. These cardioinhibitory drugs either block beta-adrenoceptors on the heart (i.e., beta-blockers) or L-type calcium channels (i.e., calcium-channel blockers ), which decreases cardiac output by decreasing heart rate and contractility (inotropy) . Vasodilator drugs , which decrease systemic vascular resistance, are also used to treat hypertension. Included in these drugs are alpha-adrenoceptor antagonists ( alpha-blockers ), direct-acting vasodilators , angiotensin-converting enzyme inhibitors and angiotensin receptor blockers . A complete list of drugs used to treat hypertension can be found by clicking here . Primary hypertension accounts for approximately 90-95% of patients diagnosed with hypertension. Unlike secondary hypertension, there is no known cause of primary hypertension. Despite many years of active research, there is no unifying hypothesis to account for the pathogenesis of primary hypertension. There is a natural progression of this disease that suggests early elevations in blood volume and cardiac output might initiate subsequent changes in the systemic vasculature (increased resistance). This has suggested to some researchers that a basic underlying defect in many hypertensive patients is an inability of the kidneys to adequately handle sodium. Increased sodium retention could then account for the increase in blood volume.  In chronic, long-standing hypertension, blood volume and cardiac output are often normal, therefore the hypertension is sustained by an elevation in systemic vascular resistance rather than by an increase in cardiac output. This increased resistance is caused by a thickening of the walls of resistance vessels and by a reduction in lumen diameters. There is also evidence for increased vascular tone. This could be mediated by enhanced sympathetic activity or by increased circulating levels of angiotensin II. In recent years, considerable evidence has suggested that changes in vascular endothelial function may cause the increase in vascular tone
  • Can you see that age is a risk factor?
  • African-Americans have a greater prevalence of hypertension (38% men; 39% of women) than non-Hispanic whites (33% of men; 25% women). The risk of developing elevated BP is 2-6 times higher in overweight than in normal-weight individuals. Weight management is a treatment for HBP. Prevalence of of Hispanic population is similar to the non-Hispanic whites.
  • Epidemiological studies of populations support the role of salt in the develop of HBP. Approximately 30-50% of Hypertensive individuals and ~ 25% normotensive individuals are salt sensitive. Hypertension and stroke is the leading cause of death in countries with very high salt consumption (9-12 g/day).
  • 5-7% of the hypertension in the population is due to alcohol consumption. Three drinks a day is the threshold for raising BP.
  • In the Framingham Study, medium to high levels of activity were protective against developing stroke.
  • Other Dietary Factors Potassium: In population studies, dietary potassium and blood pressure are inversely related. High potassium intakes are associated with lower BP. Calcium: In the Nurse’s Health Study, consuming the RDA for calcium resulted in lower risk of developing hypertension than consuming lower levels (400 mg/day). Magnesium is a potent inhibitor of vascular smooth muscle contraction and may play a role in blood pressure regulation as a vasodilator.
  • The relationship between obesity and BP appears to be linear and exists throughout the non-obese range. But the strength of the association of obesity with hypertension varies among different racial and ethnic groups. Generally, risk estimates suggest that approximately 75 and 65 percent of the cases of hypertension in men and women, respectively, are directly attributable to an overweight condition and obesity. Most Americans consume about 4,000 - 6,000 mg sodium/day.
  • Convenience food must be >360 mg/serving individual food or >480 mg/serving meal

Hypertension Hypertension Presentation Transcript

  • Hypertension
  • Hypertension Blood pressure levels are a function of cardiac output multiplied by peripheral resistance (the resistance in the blood vessels to the flow of blood)
  • Hypertension The major factors which help maintain blood pressure (BP) include the sympathetic nervous system and the kidneys. Optimal healthy blood pressure is a systolic blood pressure of <120 mmHg and a diastolic blood pressure of <80 <120/80.
  • HypertensionCategory Systolic Blood Diastolic Blood Pressure PressureNormal < 120 <80Pre-hypertension 120-139 80-89Hypertension – 140-159 90-99Stage 1Hypertension – >160 >100Stage 2
  • Hypertension Approximately one in four American adults has hypertension. As many as 2.8 million children also have high blood pressure. The prevalence of hypertension increases with age.
  • Prevalence of Hypertension byAge Age  % Hypertensive  18-29  4  30-39  11  40-49  21  50-59  44  60-69  54  70-79  64  80+  65
  • Hypertension When the normal regulatory mechanisms fail, hypertension develops. Hypertension is so dangerous because it gives off no warning signs or symptoms.
  • Untreated hypertension can result in: Arteriosclerosis --Kidney damage Heart Attack --Stroke Enlarged heart --Blindness
  • Factors Influencing the Development ofHypertension High-normal blood pressure Family history of hypertension African-American ancestry Overweight
  • Factors Influencing the Development of Hypertension Excess Consumption of Sodium Chloride Certain segments of the population are ‘salt sensitive’ because their blood pressure is affected by salt consumption
  • Factors Influencing the Development ofHypertension Alcohol consumption
  • Factors Influencing the Development ofHypertension  Exercise  Less active individuals are 30-50% more likely to develop hypertension.
  • Factors Influencing the Development of Hypertension Other Dietary Factors Potassium: Calcium: Magnesium:
  • Treatment for Hypertension Maintain a healthy weight, lose weight if overweight. Be more physically active. Drink alcoholic beverages in moderation. Reduce the intake of salt and sodium in the diet to approximately 2400 mg/day.
  • The DASH Diet The Dietary Approaches to Stop Hypertension clinical trial (DASH) Diet rich in fruits, vegetables, and low fat dairy foods, can substantially lower blood pressure in individuals with hypertension and high normal blood pressure.
  • Dash Study Control:  Ca, Mg, & K ~ 25% of US diet  Macronutrients and fiber ~ US average Fruits and Vegetables  Fruits and vegetables increased to 8.5 servings  K and Mg to 75% Combination:  Add 2-3 servings low-fat dairy to fruit & vegetable diet.  Ca, K and Mg increased to 75%
  • Dash Study Outcomes Fruit and Vegetable Diet:  Decrease in systolic and diastolic blood pressure in entire study group and in the hypertensive subgroup. Combination Diet:  Significant decrease in both systolic and diastolic blood pressure in both groups.  Greatest drop was in systolic BP in hypertensive group (11.4 mmHg)
  • Dash Diet Implications Combination diet affects comparable to pharmacological trails in mild hypertension. Population wide reductions in blood pressure similar to DASH results would reduce CHD by ~ 15% and stroke by ~27% Great potential in susceptible groups: African Americans and elderly.
  • The DASH Diet The DASH Diet includes: 7-8 servings of grains and grain products 4-5 servings of vegetables 4-5 servings of fruits 2-3 servings of low fat dairy products 2 or less servings of meat, poultry and fish 2-3 servings of fats and oils Nuts, seeds and dry beans 4-5 times /week Limited ‘sweets’ low in fat.
  • Effects of increasing Calcium-Rich DairyFood in Black Hypertensives Increases urinary sodium excretion Decreases volume Decreases peripheral vascular resistance Decrease blood pressure Reduces left ventricular mass and risk of left ventricular hypertrophy Effects sustained for one-year period of study
  • Sodium in Foods Conversion of milligrams to milliequivalents (mEq):  mg/atomic weight x valence = mEq. Atomic weight sodium = 23, valence = 1 2400 mg/23 x 1 = 104.3 mEq sodium
  • Reducing Sodium in the Diet Use fresh poultry, fish and lean meat, rather than canned or processed. Buy fresh, plain frozen or canned with “no salt added” vegetables. Use herbs, spices and salt-free seasoning blends in cooking and at the table; decrease or eliminate use of table salt. Choose ‘convenience’ foods that are lower in sodium.
  • Reducing Sodium in the Diet When available, buy low- or reduced- sodium or ‘no-salt-added’ versions of foods like:  Canned soup, canned vegetables, vegetable juices  cheeses, lower in fat  condiments like soy sauce  crackers and snack foods like nuts  processed lean meats
  • Food LabelsClaim AmountLow Sodium >140 mg/servingVery Low Sodium >35 mg/servingSodium Free >5 mg/servingReduced Sodium 25% less than original