Chapter 36

Medical Nutrition Therapy in Hypertension

Hypertension

 Persistently high arterial blood pressure, defined as systolic blood pressure above 140 mm Hg and/or diastolic blood pressure above 90 mm Hg © 2004, 2002 Elsevier Inc. All rights reserved.

Circulatory Diseases/Problems

1. Hypertension (HTN) 2. Hyperlipidemias 3. Atherosclerosis 4. Coronary heart disease 5. Congestive heart failure 6. Cerebrovascular disease 7. Peripheral vascular atherosclerotic occlusive disease © 2004, 2002 Elsevier Inc. All rights reserved.

Circulatory Systems in the Body

1. Coronary—supplies blood to heart muscle (can form collateral circulation) 2. Cerebral—supplies blood to head 3. Splanchnic—supplies blood to abdomen (exercise removes blood and food attracts blood to this area) 4. Pulmonary—supplies blood to lungs (O 2 and CO 2 exchange) © 2004, 2002 Elsevier Inc. All rights reserved.

Measures of Heart Function

1. Beats or pulse 2. BP systolic and diastolic 3. ECG © 2004, 2002 Elsevier Inc. All rights reserved.

Determinants of Blood Pressure

1. Blood volume 2. Vascular resistance to pressure 3. Heart stroke volume © 2004, 2002 Elsevier Inc. All rights reserved.

Cardiac Output

■ Amount of blood pumped by heart (vol/min) ■ Stroke volume times heart rate © 2004, 2002 Elsevier Inc. All rights reserved.

Vascular Resistance

■ Viscosity of blood ■ Width of vessels—(constriction or dilation)—controlled by muscle tone in vessel walls © 2004, 2002 Elsevier Inc. All rights reserved.

Regulation of Blood Pressure

1. Sympathetic nervous system (SNS)—responds immediately; baroreceptors monitor BP Vasomotor center in brain SNS innervated tissues contract or dilate vascular bed 2. Renin-angiotensin system—retains Na and H 2 O to increase blood volume; constricts blood vessels; increases aldosterone 3. Kidneys—respond to renin-angiotensin system; aldosterone and antidiuretic hormone (ADH) are sent out as needed © 2004, 2002 Elsevier Inc. All rights reserved.

Homeostatic Control of Blood Pressure

 Short term —Sympathetic nervous system —Vasoconstriction —Vasodilation  Long term —Fluid volume —Renin-angiotensin system © 2004, 2002 Elsevier Inc. All rights reserved.

Hypertension

1. 90% HTN is essential HTN (cause unknown; perhaps prenatal impacts?) 2. 10% HTN is secondary to other diseases 3. HTN is a risk factor for MI, CVA, renal failure © 2004, 2002 Elsevier Inc. All rights reserved.

Renin-Angiotensin Cascade

Redrawn from Guyton AC:

Textbook of medical physiology,

ed 8, Philadelphia, 1991, WB Saunders.

© 2004, 2002 Elsevier Inc. All rights reserved.

Classification of Blood Pressure for Adults Ages 18 Years and Older

From the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: Sixth Report (JNC VI),

Arch Intern Med

157:2413, 1997.

*Not taking antihypertensive drugs and not acutely ill. When systolic and diastolic blood pressures fall into different categories, the higher category should be selected to classify the individual’s blood pressure status. For example, 160/92 mm Hg should be classified as stage 2 hypertension, and 174/120 mm Hg should be classified as stage 3 hypertension. Isolated systolic hypertension is defined as systolic blood pressure 140 mm Hg or greater and diastolic blood pressure less than 90 mm Hg and staged appropriately (e.g., 170/82 mm Hg is defined as stage 2 isolated systolic hypertension). In addition to classifying stages of hypertension on the basis of average blood pressure levels, clinicians should specify presence or absence of target organ disease and additional risk factors. This specificity is important for risk classification and treatment.

†Optimal blood pressure with respect to cardiovascular risk is less than 120/80 mm Hg. However, unusually low readings should be evaluated for clinical significance.

‡Based on the average of two orr more readings taken at each of two or more visits after an initial screening.

© 2004, 2002 Elsevier Inc. All rights reserved.

Treatment of Hypertension—Cause

Algorithm content developed by John Anderson, PhD, and Sanford C. Garner, PhD, 2000.

© 2004, 2002 Elsevier Inc. All rights reserved.

Treatment of Hypertension— Pathophysiology

Algorithm content developed by John Anderson, PhD, and Sanford C. Garner, PhD, 2000.

© 2004, 2002 Elsevier Inc. All rights reserved.

Treatment of Hypertension— Medical and Nutritional Therapy

Algorithm content developed by John Anderson, PhD, and Sanford C. Garner, PhD, 2000.

© 2004, 2002 Elsevier Inc. All rights reserved.

Risk Factors for Developing Hypertension

(Adapted from National High Blood Pressure Education Program Working Group report on primary prevention of hypertension. Arch Intern Med 153:186, 1993. Copyright 1993, American Medical Association. Reprinted with permission.) © 2004, 2002 Elsevier Inc. All rights reserved.

Components of Cardiovascular Risk Stratification in Patients with Hypertension

(From The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. sixth report (JNC VI). Arch Intern Med 157:2413, 1997.) © 2004, 2002 Elsevier Inc. All rights reserved.

Untreated or Uncontrolled Hypertension

 Leads to increased Workload on heart Damage to arteries Atherosclerosis Coronary heart disease esp. CHF Strokes Transient ischemic attacks (TIAs) Kidney damage Microvascular hemorrhages in brain and eye © 2004, 2002 Elsevier Inc. All rights reserved.

Medical Management of Hypertension Based on Risk

 High-normal BP and Stage 1 hypertension in low- or medium-risk group —Begin with trial of lifestyle modification for 6 to 12 months  High-normal BP and Stage 1 hypertension in high-risk group —Begin with drug therapy in addition to lifestyle modification  Stages 2 and 3 all risk groups —Begin with drug therapy in addition to lifestyle modification © 2004, 2002 Elsevier Inc. All rights reserved.

Steps to Manage High Blood Pressure

 Weight management —If over 115% of ideal body weight, exercise and hypocaloric diet estimate 25 kcal/kg minus 500 to 1000kcal/day  Salt restriction —6 g NaCl or 2400 mg Na/day © 2004, 2002 Elsevier Inc. All rights reserved.

Levels of Na Restriction

g Na

4 2-3 1 0.5

mEq Na

174 87-130 43 22

Description

No added salt Mild to moderate restriction Strict sodium restriction Severe sodium restriction © 2004, 2002 Elsevier Inc. All rights reserved.

Response to Dietary Rx

 Salt sensitive respond well to sodium restriction  Most respond to increased potassium in diet.

– 1.1 to 3.3 g Na is safe – 1.9 to 5.6 g K is recommended to achieve ratio Na:K of 1, which is goal  If taking a potassium-wasting diuretic drug, increased potassium in diet is essential.

 Most respond to increased calcium (at least the RDA)—use the DASH diet protocol © 2004, 2002 Elsevier Inc. All rights reserved.

DASH Diet

 Works within 14 days  Lowers BP quite well  Includes more potassium, calcium, other nutrients © 2004, 2002 Elsevier Inc. All rights reserved.

DASH Diet —cont’d

 Pattern —7-8 whole grains —4-5 vegetables —4-5 fruits —2-3 low-fat or fat-free dairy products —6 oz or less meat/poultry/fish —4-5 servings nuts, beans, or legumes/week —2-3 servings fat (total kcal = 27% fat) © 2004, 2002 Elsevier Inc. All rights reserved.

DASH Diet Website

 www.nhlbi.nih.gov/health/public/heart/hb p/dash/new_dash.pdf

© 2004, 2002 Elsevier Inc. All rights reserved.

Food Label Terms

 Sodium free, no sodium = <5 mg/serving  Very low sodium = <35 mg/serving and per 100 g food  Low sodium = <140 mg/serving and per 100 g food  Reduced sodium = 50% less than comparison food © 2004, 2002 Elsevier Inc. All rights reserved.

Salt Substitutes

 Composition: KCl, CaCl, Al-Cl  KCl can provide extra potassium for those taking diuretics  KCl can be harmful if patient has renal insufficiency  “Lite” salt contains sodium  Some spices and herbs are low in sodium  Others are high in sodium © 2004, 2002 Elsevier Inc. All rights reserved.

Classification of Antihypertensive Drugs

 Diuretics —Thiazides —Loop diuretics —Potassium-sparing diuretics  Beta blockers  Alpha-beta blockers  Alpha1 receptor blockers  ACE inhibitors  Calcium antagonists  Direct vasodilators © 2004, 2002 Elsevier Inc. All rights reserved.

Antihypertensive Drugs

Volume Depletors Diuretics Thiazides Chlorthalidone Metolazone Loop diuretics Furosemide K+ sparing Spironolactone Triamterene Amiloride Sympathetic Blockers Peripheral Reserpine Guanethidine Central: methyldopa Clonidine ß-receptor: propranolol Atenolol Metoprolol Nadolol Timolol α-receptor: phentolamine Phenoxybenzamine Prazosin

© 2004, 2002 Elsevier Inc. All rights reserved.

Lifestyle Modifications for Prevention of Hypertension

 Lose weight if overweight  Limit alcohol  Increase physical activity  Decrease sodium intake  Keep potassium intake at adequate levels  Take in adequate amounts of calcium and magnesium  Decrease intake of saturated fat and cholesterol  Stop smoking © 2004, 2002 Elsevier Inc. All rights reserved.

Summary

 Lifestyle modifications for prevention of hypertension—quite effective!

 Management of hypertension—very important to reduce risk of heart attack or stroke!

© 2004, 2002 Elsevier Inc. All rights reserved.