Disorders of Blood Pressure Regulation

1. Disorders of Blood Pressure Regulation

2. Arterial Blood Pressure (Definitions) • Systolic pressure: pressure at the height of the pressure pulse • Diastolic pressure: the lowest pressure • Pulse pressure: the difference between systolic and diastolic pressure • Mean arterial pressure: the average pressure in the arterial system during ventricular contraction and relaxation

4. Arterial Blood Pressure • Represents the pressure of the blood as it moves through the arterial system • Cardiac output = HR x SV • Peripheral resistance (PR) • Mean arterial pressure = CO x PR

5. Mechanisms of Blood Pressure Regulation • Short-term regulation:corrects temporary imbalances in blood pressure • Neural mechanisms • Humoral mechanisms • Long-term regulation: controls the daily, weekly, and monthly regulation of blood pressure • Renal mechanism

6. Factors Determining Systolic and Diastolic Blood Pressure • Systolic pressure • The characteristics of the stroke volume being ejected from the heart • The ability of the aorta to stretch and accommodate the stroke volume • Diastolic pressure • The energy stored in the aorta as its elastic fibers are stretched during systole • The resistance to the runoff of blood from the peripheral blood vessels

7. Factors Influencing Mean Arterial Blood Pressure • Physical • Blood volume and the elastic properties of the blood vessels • Physiologic factors • Cardiac output • Peripheral vascular resistance

8. Question • Which of the following does not directly affect arterial blood pressure? • Heart rate • Peripheral resistance • Venous constriction • Blood volume

9. Answer • Heart rate • Peripheral resistance • Venous constriction: Venous constriction will not affect arterial pressure, but the other factors will have immediate effects. • Blood volume

10. What is Blood Pressure? • The force of blood against the wall of the arteries. • Systolic- as the heart beats • Diastolic - as the heart relaxes • Written as systolic over diastolic. • Normal Blood pressure is less than 130 mm Hg systolic and less than 85 mm Hg diastolic.

11. A consistent blood pressure of 140/90 mm Hg or higher is considered high blood pressure. • It increases chance for heart disease, kidney disease, and for having a stroke. • 1 out of 4 Americans have High Bp. • Has no warning signs or symptoms.

12. Why is High Blood Pressure Important? • Makes the Heart work too hard. • Makes the walls of arteries hard. • Increases risk for heart disease and stroke. • Can cause heart failure, kidney disease, and blindness.

13. How Does It Effect the Body?The Brain • High blood pressure is the most important risk factor for stroke. • Can cause a break in a weakened blood vessel which then bleeds in the brain.

14. The Heart • High Blood Pressure is a major risk factor for heart attack. • Is the number one risk factor for Congestive Heart Failure.

15. The Kidneys • Kidneys act as filters to rid the body of wastes. • High blood pressure can narrow and thicken the blood vessels. • Waste builds up in the blood, can result in kidney damage.

16. The Eyes • Can eventually cause blood vessels to break and bleed in the eye. • Can result in blurred vision or even blindness.

17. The Arteries • Causes arteries to harden. • This in turn causes the kidneys and heart to work harder. • Contributes to a number of problems.

18. What causes High Blood Pressure? • Causes vary • Narrowing of the arteries • Greater than normal volume of blood • Heart beating faster or more forcefully than it should • Another medical problem • The exact cause is not known.

19. Who can develop High Blood Pressure? • Anyone, but it is more common in: • African Americans- get it earlier and more often then Caucasians. • As we get older. 60% of Americans over 60 have hypertension. • Overweight, family history • High normal bp:135-139/85-89 mm Hg.

20. Detection • Dr.’s will diagnose a person with 2 or more readings of 140/90mm Hg or higher taken on more than one occasion. • White-Coat Hypertension • Measured using a spygmomameter.

22. Categories of High Blood Pressure • Ages 18 Years and Older) • Blood Pressure Level (mm Hg) • Category Systolic Diastolic • Optimal** < 120 < 80 • Normal < 130 < 85 • High Normal 130–139 85–89

23. Categories of High Blood Pressure High Blood Pressure • Stage 1 140–159 /90–99 • Stage 2 160–179 /100–109 • Stage 3 180 /110

24. Categories of Hypertension • Primary hypertension (essential hypertension) • Chronic elevation in blood pressure that occurs without evidence of other disease • Also known as Idiopathic or Essential hypertension • Secondary hypertension • Elevation of blood pressure that results from some other disorder, such as kidney disease

25. Primary Hypertension

26. Primary Hypertension • Results from a complicated interaction between genetics and the environment • Increases peripheral resistance • Increased blood volume • Sympathetic Nervous System • RAAS

27. Increased Sympathetic Nervous System Activity Leading to Hypertension • Increase Heart Rate and Peripheral Resistance • Vascular Remodeling • Causes narrowing of vessels and vasospasms

29. RAAS out of control • Maintains adequate blood pressure • If not functioning can lead to • Persistent increases in peripheral resistance and • Renal salt retention • Contributes to insulin resistance • Causes endothelial dysfunction and narrowing of blood vessels

30. Angiotensin II • Structural changes to blood vessels • Remodeling • Permanent increases in PR • Hypertrophy of the myocardium

31. Naturiuretic peptide • Atrial natriuretic hormone (ANH) • Powerful vasodilator secreted by the atria of the heart • Decreases sodium reabsorption • Reduces Aldosterone secretion

32. Atrial Natriuretic Peptides • Atrial natriuretic peptide • Brain natriuretic peptide • C-type natriuretic peptide • urodilantin • Regulates sodium excretion • Affected by • Stretch of the myocardium • Excessive sodium intake • Inadequate intake of potassium, magnesium, calcium • Obesity

35. Inflammation and Hypertension • Endothelial injury causes release of • Vasoactive inflammatory cytokines • Histamine • Prostaglandins • In the Kidneys • Vasoconstriction and decreased perfusion leads to ischemia and tissue necrosis • Increased Salt Retention!!!!!

37. Obesity and Hypertension • Adipocytes secrete Leptin and Adiponectin • Leptin - interacts with the hypothalamus to control body weight and fat deposition • Inhibits the appetite • Chronically high levels of Leptin lead to SNS • Adiponectin - reduced during Obesity leading to • Activation of the RAAS • Activation of the SNS

38. Insulin Resistance and Hypertension • Associated with Endothelial Dysfunction • Insulin protects endothelial cell lining and production of NO • Diabetes and insulin resistance causes changes in • SNS • RAAS • Leads to hypertension

39. Question • Renal failure results in Na+ and water retention. This results in hypertension. How would you classify this type of hypertension? • Primary hypertension • Secondary hypertension • Malignant hypertension • Systolic hypertension

40. Answer • Primary hypertension • Secondary hypertension: Secondary hypertension accompanies an underlying disease. • Malignant hypertension • Systolic hypertension

41. Secondary Hypertension

42. Most Common Causes of Secondary Hypertension • Kidney disease (renovascular hypertension) • Adrenal cortical disorders • Pheochromocytoma • Sleep apnea

43. Adrenal Disorders and Secondary Hypertension • Cushing Syndrome • Facilitates sodium and water retension • Primary Aldosteronism • Excess Aldosterone • Promotes sodium retention • Pheochromocytoma • Excess catecholamines • Increases vascular tone and increases peripheral resistance • Eating too much Licorice raises blood pressure too!

44. Sleep Apnea • Intermittent inability to breath while sleeping • Causes ischemia • Endothelial injury • Myocardial damage • Kidney damage

45. Chronic Hypertension • Damages vessel walls • Vascular remodeling • Secretion of • Angiotension II, Catecholamines, Inflammatory cytokines • Myocardial damage due to increase work load • Ischemia to the brain and retina of the eye • RAAS secretion stimulated due to reduced blood flow

46. Types of Hypertension in Pregnancy • Gestational hypertension • Chronic hypertension • Preeclampsia/eclampsia • Preeclampsia superimposed on chronic hypertension

47. Pre-Eclampsia/Eclampsia • Unknown Etiology • Possible causes may include: • Insufficient blood flow to the uterus • Damage to the blood vessels • A problem with the immune system • Poor diet

48. Diagnosis and Treatment of Hypertension in Pregnancy • Early prenatal care • Refraining from alcohol and tobacco use • Salt restriction • Bed rest • Carefully chosen antihypertensive medications

49. High Blood Pressure in Children and Adolescents • Blood pressure norms for children are based on age, height, and gender-specific percentiles. • Secondary hypertension is the most common form of high blood pressure in infants and children. • Kidney abnormalities • Pheochromocytomaand adrenal cortical disorders • In infants, hypertension is associated most commonly with high umbilical catheterization and renal artery obstruction caused by thrombosis.

50. Factors Affecting Treatment Strategies for Hypertension • Lifestyle • Demographics • Motivation for adhering to the drug regimen • Other disease conditions and therapies • Potential for side effects