Chapter 32 Hypertension Flashcards
Hypertension
- Direct relationship between hypertension and?
- Affects __ of adults in U.S.
- Additional ___% have prehypertension
- High priority health concern identified in?
- cardiovascular disease
- Affects 33% of adults in U.S.
- Additional 30% have prehypertension
- High priority health concern identified in Healthy People 2020
Blood pressure (BP) is the force exerted by the blood against the walls of the blood vessel. It must be adequate to maintain tissue perfusion during activity and rest. The maintenance of normal BP and tissue perfusion requires the integration of both?
systemic factors and local peripheral vascular effects. BP is primarily a function of cardiac output (CO) and systemic vascular resistance (SVR)
CO is?
total blood flow through the systemic or pulmonary circulation per minute. It is described as the stroke volume (SV) or the amount of blood pumped out of the left ventricle per beat (approximately 70 mL) multiplied by the heart rate (HR).
Factors influencing BP: Sympathetic nervous system (SNS)
- Activation increases HR and cardiac contractility
- Vasoconstriction and renin release
- Increases CO and SVR
Systemic vascular resistance (SVR) is the force opposing the movement of blood within the blood vessels. The radius of the small arteries and arterioles is the principal factor determining SVR. As arteries narrow, resistance to blood flow increases. As arteries dilate, resistance to blood flow decreases. A small change in the radius of the arterioles creates a major change in the SVR. If SVR is increased and CO remains constant or increases, what happens?
arterial BP will increase
The mechanisms that regulate BP can affect either CO or SVR, or both. Regulation of BP is a complex process involving both short-term (seconds to hours) and long-term (days to weeks) mechanisms.
1) Short-term mechanisms, including?
2) Long-term mechanisms include?
1) sympathetic nervous system (SNS) and vascular endothelium, are active within a few seconds.
2) renal and hormonal processes that regulate arteriolar resistance and blood volume.
- In a healthy person these regulatory mechanisms function in response to the body’s demands.
Sympathetic Nervous System:
The nervous system, which reacts within seconds after a drop in BP, increases BP primarily by activating the SNS. Increased SNS activity increases?
HR and cardiac contractility, produces widespread vasoconstriction in the peripheral arterioles, and promotes the release of renin from the kidneys. The net effect of SNS activation is to increase BP by increasing both CO and SVR.
Sympathetic Nervous System: Specialized nerve cells called baroreceptors (pressoreceptors) are located in the carotid arteries and arch of the aorta.
1) These cells sense?
2) SNS efferent nerves innervate cardiac and vascular smooth muscle cells. Under normal conditions, a low level of continuous?
1) changes in BP and transmit this information to the vasomotor centers in the brainstem. The brainstem sends this information through complex networks of neurons that excite or inhibit efferent nerves.
2) SNS activity maintains vascular tone. BP may be reduced by withdrawal of SNS activity or by stimulation of the parasympathetic nervous system (PNS). The PNS decreases the HR (via the vagus nerve) and thereby decreases CO.
Sympathetic nervous system: The neurotransmitter norepinephrine (NE) is released from SNS nerve endings. 1) NE activates receptors located in the?
2) The response to NE depends on the type of receptors present. SNS receptors are classified as α1, α2, β1, and β2. The smooth muscle of the blood vessels has?
3) α-Adrenergic receptors located in the peripheral vasculature cause what when stimulated by NE?
4) β1-Adrenergic receptors in the heart respond to NE and epinephrine with?
5) β2-Adrenergic receptors are activated primarily by?
1) sinoatrial node, myocardium, and vascular smooth muscle.
2) α-adrenergic and β2-adrenergic receptors.
3) vasoconstriction when stimulated by NE.
4) increased HR (chronotropic), increased force of contraction (inotropic), and increased speed of conduction (dromotropic).
5) epinephrine released from the adrenal medulla and cause vasodilation
Sympathetic Nervous System Receptors Affecting BP
α1 Receptor:
-Location
-Response when activated
1)
- Location: Vascular smooth muscle
- Response when activated: Vasoconstriction
2)
- Location: Heart
- Response when activated: Increased contractility (positive inotropic effect)
Sympathetic Nervous System Receptors Affecting BP
α2 Receptor:
-Location
-Response when activated
1)
- Location: Presynaptic nerve terminals
- Response when activated: Inhibition of norepinephrine release
2)
- Location: Vascular smooth muscle
- Response when activated: Vasoconstriction
Sympathetic Nervous System Receptors Affecting BP
β1 Receptor:
-Location
-Response when activated
1)
- Location: Heart
- Response when activated:
* Increased contractility (positive inotropic effect)
* Increased heart rate (positive chronotropic effect)
* Increased conduction (positive dromotropic effect)
2)
- Location: Juxtaglomerular cells of the kidney
- Response when activated: Increased renin secretion
Sympathetic Nervous System Receptors Affecting BP
β2 Receptor:
-Location
-Response when activated
- Location: Smooth muscle of blood vessels in heart (e.g., coronary arteries), lungs (e.g., bronchi), and skeletal muscle
- Response when activated: Vasodilation
Sympathetic Nervous System Receptors Affecting BP
Dopamine Receptors:
-Location
-Response when activated
- Location: Primarily renal blood vessels
- Response when activated: Vasodilation
The sympathetic vasomotor center interacts with many areas of the brain to maintain normal BP under various conditions. It is activated during times of pain, stress, and exercise. The SNS response causes an appropriate increase in CO and BP to adjust to the body’s increased O2 demands.
- During postural change from lying to standing, there is a transient?
decrease in BP. The vasomotor center is stimulated, and the SNS response causes peripheral vasoconstriction and increased venous return to the heart. If this response did not occur, blood flow to the brain would be inadequate, resulting in dizziness or syncope.
Baroreceptors have an important role in the maintenance of BP stability during normal activities.
1) They are sensitive to stretching and, when stimulated by an increase in BP, they?
2) When a fall in BP is sensed by the baroreceptors, the?
1) send inhibitory impulses to the sympathetic vasomotor center. Inhibition of the SNS results in decreased HR, decreased force of contraction, and vasodilation in peripheral arterioles.
2) SNS is activated. The result is constriction of the peripheral arterioles, increased HR, and increased contractility of the heart. In long-standing hypertension, the baroreceptors become adjusted to elevated BP levels and recognize this level as their new “normal.”
- Sensitive to stretching
- Send impulses to sympathetic vasomotor center
Baroreceptors
The vascular endothelium is a single-cell layer that lines the blood vessels.
- Functions:
- Functions: platelet adhesion, coagulation regulation, immune function, and regulation of fluid control within the vessel and extravascular space. The endothelium can also cause adhesion and aggregation of neutrophils and stimulate smooth muscle growth.
- essential to the regulation and maintenance of the vasodilating and vasoconstricting substances.9 Endothelium-derived vasoactive substances include nitric oxide (NO) and prostacyclin, which are both vasodilators. Another product of the endothelium is endothelin (ET), which is a potent vasoconstrictor (Fig. 32-1). A disruption or dysfunction of arterial tone (either through excessive constriction or dilation) is an early warning signal of CVD.
Produces vasoactive substances to maintain low arterial tone
Vascular endothelium
- Control sodium excretion and ECF volume
- RAAS system
- Prostaglandins
Renal system
Renal System
- Control sodium excretion and ECF volume
The kidneys contribute to BP regulation by controlling sodium excretion and extracellular fluid (ECF) volume. Sodium retention results in water retention, which causes an increase in ECF volume. This increases the venous return to the heart and stroke volume. Together these increase CO and BP.
Renal System
- RAAS system
plays an important role in BP regulation.
- juxtaglomerular apparatus in the kidney secretes renin in response to SNS stimulation, decreased blood flow through the kidneys, or decreased serum sodium concentration.
- Renin (enzyme that converts angiotensinogen to angiotensin I) Angiotensin I is converted to angiotensin II (A-II) by angiotensin-converting enzyme (ACE).
- A-II increases BP by two different mechanisms. First, A-II is a potent vasoconstrictor and increases SVR. This results in an immediate increase in BP. Second, over a period of hours or days, A-II increases BP indirectly by stimulating the adrenal cortex to secrete aldosterone
- A-II also acts at a local level within the heart and blood vessels. These effects include vasoconstriction and tissue growth that result in remodeling of the vessel walls, which can be due to or caused by endothelial dysfunction. These changes are linked to the development of primary hypertension and also the long-term effects of hypertension (e.g., atherosclerosis, renal disease, cardiac hypertrophy)
Renal system
- Prostaglandins
Prostaglandins (PGE2 and PGI2) secreted by the renal medulla have a vasodilator effect on the systemic circulation. This results in decreased SVR and lowering of BP. The natriuretic peptides (atrial natriuretic peptide [ANP] and b-type natriuretic peptide [BNP]) are secreted by heart cells. They antagonize the effects of antidiuretic hormone (ADH) and aldosterone. This results in natriuresis (excretion of sodium in urine) and diuresis, resulting in reduced blood volume and BP.
Factors influencing BP: Endocrine system main points
- Epinephrine and norepinephrine from adrenal medulla
- Aldosterone from adrenal cortex
- ADH from posterior pituitary
Endocrine System
1) Stimulation of the SNS results in release of epinephrine along with a small fraction of NE by the adrenal medulla. Epinephrine increases the?
2) Epinephrine activates β2-adrenergic receptors in?
3) In peripheral arterioles with only α1-adrenergic receptors (skin and kidneys), epinephrine causes?
1) CO by increasing the HR and myocardial contractility.
2) peripheral arterioles of skeletal muscle, causing vasodilation.
3) vasoconstriction.
Endocrine System
- A-II stimulates the adrenal cortex to release aldosterone. Aldosterone stimulates the?
kidneys to retain sodium and water. This increases blood volume and CO
Endocrine System
- An increased blood sodium and osmolarity level stimulates the release of?
ADH from the posterior pituitary gland. ADH increases the ECF volume by promoting the reabsorption of water in the distal and collecting tubules of the kidneys. The resulting increase in blood volume causes an increase in CO and BP.
Hypertension is defined as a persistent?
systolic BP (SBP) of 140 mm Hg or more, diastolic BP (DBP) of 90 mm Hg or more, or current use of antihypertensive medication
Prehypertension is defined as?
SBP of 120 to 139 mm Hg or DBP of 80 to 89 mm Hg
Isolated systolic hypertension (ISH) is defined as an average
SBP of 140 mm Hg or more, coupled with an average DBP of less than 90 mm Hg.
- SBP increases with aging.
- DBP rises until approximately age 55 and then declines. - Control of ISH decreases the incidence of stroke, heart failure, and death.
Blood pressure classification:
Isolated systolic hypertension
Hypertension Stage 1
Hypertension Stage 2
- Isolated systolic hypertension SBP >140 mm Hg with DBP <90 mm Hg - Hypertension Stage 1 SBP 140–149 or DBP 90–99 - Hypertension Stage 2 SBP >160 or DBP >100
The nurse determines that the patient has stage 2 hypertension when the patient’s average blood pressure is
a. 155/88 mm Hg.
b. 172/92 mm Hg.
c. 160/110 mm Hg.
d. 182/106 mm Hg.
c. 160/110 mm Hg.
Primary hypertension main points
- Also called essential or idiopathic hypertension
- Elevated BP without an identified cause
- 90% to 95% of all cases
- Exact cause unknown but several contributing factors
Primary Hypertension (essential or idiopathic)
- elevated BP without an identified cause, and it accounts for 90% to 95% of all cases of HTN
- several contributing factors include changes in endothelial function related to either vasoconstricting or vasodilating agents, increased SNS activity, overproduction of sodium-retaining hormones, increased sodium intake, greater-than-ideal body weight, diabetes, tobacco use, and excessive alcohol intake.
Secondary hypertension is elevated BP with a specific cause that often can be identified and corrected. This type of hypertension accounts for 5% to 10% of hypertension in adults.
1) Secondary hypertension should be suspected in people who suddenly develop?
2) Clinical findings that suggest secondary hypertension relate to the?
1) high BP, especially if it is severe.
2) underlying cause. For example, an abdominal bruit heard over the renal arteries may indicate renal disease. Treatment of secondary hypertension is aimed at removing or treating the underlying cause. Secondary hypertension is a contributing factor to hypertensive crisis
Secondary hypertension main points
- Elevated BP with a specific cause
- 5% to 10% of adult cases
- Clinical findings relate to underlying cause
- Treatment aimed at removing or treating cause
Pathophysiology Primary Hypertension main points
- Persistently increased SVR
- Abnormalities in any mechanisms involved in
- maintenance of normal BP
Causes of Secondary Hypertension
- Cirrhosis
- Coarctation or congenital narrowing of the aorta
- Drug-related: estrogen replacement therapy, oral contraceptives, corticosteroids, nonsteroidal antiinflammatory drugs (e.g., cyclooxygenase-2 inhibitors), sympathetic stimulants (e.g., cocaine, monoamine oxidase)
- Endocrine disorders (e.g., pheochromocytoma, Cushing syndrome, thyroid disease)
- Neurologic disorders (e.g., brain tumors, quadriplegia, traumatic brain injury)
- Pregnancy-induced hypertension
- Renal disease (e.g., renal artery stenosis, glomerulonephritis)
- Sleep apnea
Pathophysiology of Primary Hypertension
- BP rises with any increase in?
- Increased CO is sometimes found in the person with?
- The hemodynamic hallmark of hypertension is?
- CO or SVR
- prehypertension. Later in the course of hypertension, the SVR rises and CO returns to normal.
- persistently increased SVR. This persistent elevation in SVR may occur in various ways.
Risk factor for primary hypertension: Alcohol
• Excessive alcohol intake is strongly associated with hypertension.
• Moderate intake of alcohol has cardioprotective properties; males with hypertension should limit their daily intake of alcohol? For females?
males with hypertension should limit their daily intake of alcohol to 2 drinks per day, and 1 drink per day for females with hypertension.
Risk factor for primary hypertension: Elevated serum lipids
- ↑ Levels of cholesterol and triglycerides are primary risk factors in atherosclerosis.
- Hyperlipidemia is more common in people with hypertension.
Risk factor for primary hypertension: Gender
- Hypertension is more prevalent in men in young adulthood and early middle age.
- After age 64, hypertension is more prevalent in women.
Risk factor for primary hypertension: Obesity
- Weight gain is associated with increased frequency of hypertension.
- Risk increases with central abdominal obesity.
Risk factor for primary hypertension: Ethnicity
• Incidence of hypertension is 2 times higher in African Americans than in whites.
Risk Factors for Primary Hypertension
- Age
- Alcohol
- Tobacco use
- Diabetes mellitus
- Elevated serum lipids
- Excess dietary sodium
- Gender
- Family history
- Obesity
- Ethnicity
- Sedentary lifestyle
- Socioeconomic status
- Stress
While performing blood pressure screening at a health fair, the nurse counsels which person as having the greatest risk for developing hypertension?
a. A 56-year-old man whose father died at age 62 from a stroke
b. A 30-year-old female advertising agent who is unmarried and lives alone
c. A 68-year-old man who uses herbal remedies to treat his enlarged prostate gland
d. A 43-year-old man who travels extensively with his job and exercises only on weekends
A 56-year-old man whose father died at age 62 from a stroke
HypertensionClinical Manifestations
- “Silent killer”
- Symptoms of severe hypertension
- Fatigue
- Dizziness
- Palpitations
- Angina
- Dyspnea
Clinical Manifestations
1) Hypertension is often called the “silent killer” because it is?
2) A patient with severe hypertension may experience a variety of symptoms secondary to the effects on blood vessels in the various organs and tissues or to the increased workload of the heart. These secondary symptoms include?
3) In the past, symptoms of hypertension were thought to include headache and nosebleeds. Unless BP is very high, these symptoms are no more frequent in people with hypertension than in the general population. However, patients with?
1) frequently asymptomatic until it becomes severe and target organ disease occurs.
2) fatigue, dizziness, palpitations, angina, and dyspnea.
3) hypertensive crisis may experience severe headaches, dyspnea, anxiety, and nosebleeds
Hypertension Complications: Target organ diseases occur most frequently in the?
- Heart
- Brain
- Peripheral vascular disease
- Kidney
- Eyes
Hypertension Complications:
The most common complications of hypertension are target organ diseases occurring in the?
- heart (hypertensive heart disease)
- brain (cerebrovascular disease)
- peripheral vessels (peripheral vascular disease)
- kidneys (nephrosclerosis)
- eyes (retinal damage)
Manifestations of Target Organ Disease:
- Organ: Cardiac
- Manifestations:
- Manifestations:
• Clinical, electrocardiographic, or radiologic evidence of coronary artery disease (e.g., previous MI, coronary revascularization)
• Left ventricular hypertrophy by ECG or echocardiography
• Left ventricular dysfunction or heart failure
Manifestations of Target Organ Disease:
- Organ: Cerebrovascular
- Manifestations:
- Manifestations:
• Transient ischemic attack
• Stroke
Manifestations of Target Organ Disease:
- Organ: Peripheral vascular
- Manifestations:
- Manifestations: • One or more major pulses in the extremities (except for dorsalis pedis) faint or absent • Intermittent claudication • Abdominal or carotid bruits or thrills • Aneurysm
Manifestations of Target Organ Disease:
- Organ: Renal
- Manifestations:
- Serum creatinine ≥1.5 mg/dL (130 µmol/L)
- Proteinuria (≥1+)
- Microalbuminuria
Manifestations of Target Organ Disease:
- Organ: Retinopathy
- Manifestations:
- Generalized or focal narrowing of retinal arterioles
- Arteriovenous nicking
- Hemorrhages or exudates with or without papilledema
Hypertension Diagnostic Studies
- Urinalysis
- BUN and serum creatinine
- Creatinine clearance
- Serum electrolytes, glucose
- Serum lipid profile
- Uric acid levels
- ECG
- Echocardiogram
Hypertensive heart disease: Coronary Artery Disease.
Hypertension is a major risk factor for coronary artery disease (CAD). The mechanisms by which hypertension contributes to the development of atherosclerosis are not fully known. The “response-to-injury” theory of atherogenesis suggests that hypertension?
disrupts the coronary artery endothelium. This results in a stiff arterial wall with a narrowed lumen, and accounts for a high rate of CAD, angina, and MI.
Hypertensive heart disease: Left Ventricular Hypertrophy.
Sustained high BP increases the cardiac workload and produces left ventricular hypertrophy (LVH). Initially, LVH is a compensatory mechanism that strengthens cardiac contraction and increases CO. However, increased contractility increases?
myocardial work and O2 demand. Progressive LVH, especially in the presence of CAD, is associated with the development of heart failure.
Hypertensive heart disease: Heart Failure.
Heart failure occurs when the heart’s compensatory mechanisms are overwhelmed and the heart can no longer pump enough blood to meet the body’s demands. Contractility is?
depressed, and stroke volume and CO are decreased. The patient may complain of shortness of breath on exertion, paroxysmal nocturnal dyspnea, and fatigue.
Cerebrovascular Disease.
Atherosclerosis is the most common cause of cerebrovascular disease. Hypertension is a major risk factor for cerebral atherosclerosis and stroke. Even in mildly hypertensive people, the risk of stroke is four times higher than in normotensive people. Adequate control of BP diminishes the risk of stroke.
1) Atherosclerotic plaques are commonly found at the?
2) Portions of the atherosclerotic plaque or the blood clot that forms with disruption of the plaque may break off and travel to cerebral vessels, producing a?
3) Hypertensive encephalopathy may occur after a marked rise in BP if the cerebral blood flow is not decreased by autoregulation. Autoregulation is a physiologic process that maintains?
1) bifurcation of the common carotid artery and in the internal and external carotid arteries.
2) thromboembolism. The patient may experience transient ischemic attacks or a stroke.
3) constant cerebral blood flow despite fluctuations in BP. Normally, as pressure in the cerebral blood vessels rises, the vessels constrict to maintain constant flow. When BP exceeds the body’s ability to autoregulate, the cerebral vessels suddenly dilate, capillary permeability increases, and cerebral edema develops. This produces a rise in intracranial pressure. If left untreated, patients can die quickly from brain damage.
Peripheral Vascular Disease.
Hypertension speeds up the process of atherosclerosis in the peripheral blood vessels. This leads to the development of?
-Symptom of peripheral vascular disease
peripheral vascular disease, aortic aneurysm, and aortic dissection. Intermittent claudication (ischemic leg pain precipitated by activity and relieved with rest) is a classic symptom of peripheral vascular disease.
Nephrosclerosis.
Hypertension is one of the leading causes of chronic kidney disease, especially among African Americans. Some degree of renal disease is usually present in the hypertensive patient, even those with minimally elevated BP.
1) Renal disease results from ischemia caused by the narrowing of the renal blood vessels. This leads to?
2) Laboratory indications of renal disease are?
3) Manifestation of renal disease is?
1) atrophy of the tubules, destruction of the glomeruli, and eventual death of nephrons. Initially intact nephrons can compensate, but these changes may eventually lead to renal failure.
2) albuminuria, proteinuria, microscopic hematuria, and elevated serum creatinine and blood urea nitrogen (BUN) levels.
3) An early manifestation of renal disease is usually nocturia
Retinal Damage.
The appearance of the retina provides important information about the severity and duration of hypertension. The blood vessels of the retina can be directly visualized with an ophthalmoscope.
1) Damage to the retinal vessels provides an indication of?
2) Manifestations of severe retinal damage include?
1) related vessel damage in the heart, brain, and kidneys. 2) blurring of vision, retinal hemorrhage, and loss of vision.
Most hypertension is classified as primary hypertension and testing for secondary causes is not routinely done. Basic laboratory studies are performed to?
(1) identify or rule out causes of secondary hypertension (2) evaluate target organ disease
(3) determine overall cardiovascular risk
(4) establish baseline levels before initiating therapy
Diagnostics: Routine urinalysis, BUN, and serum creatinine levels are used to screen for?
- Creatinine clearance reflects the?
- used to screen for renal involvement and provide baseline information about kidney function.
- Creatinine clearance reflects the glomerular filtration rate. Decreases in creatinine clearance indicate renal insufficiency.
Diagnostic studies:
1) Measurement of serum electrolytes, especially potassium, is important to detect?
2) Blood glucose levels assist in the diagnosis of diabetes.
3) A lipid profile provides information about additional risk factors related to?
4) Uric acid levels establish a?
5) An electrocardiogram (ECG) provides baseline information about heart status. It can identify the presence of?
6) If the patient’s age, history, physical examination, or severity of hypertension points to a secondary cause, further?
1) hyperaldosteronism, a cause of secondary hypertension.
2) Blood glucose levels assist in the diagnosis of?
3) atherosclerosis and CVD.
4) baseline, since the levels often rise with diuretic therapy.
5) LVH, cardiac ischemia, or previous MI. If LVH is suspected, echocardiography is often performed.
6) diagnostic testing is indicated.
best method for diagnosing hypertension
Ambulatory BP monitoring (ABPM)
- It is a noninvasive, fully automated system that measures BP at preset intervals over a 12-24-hour period. The equipment includes a BP cuff and a microprocessing unit that fits into a pouch worn on a shoulder strap or belt. Tell patients to hold their arm still by their side when the device is taking a reading.
BP demonstrates diurnal variability expressed as sleep-wakefulness difference. For day-active people, BP is?
- The presence of diurnal variability is confirmed with?
- highest in the early morning, decreases during the day, and is lowest at night. BP at night (during sleep) usually drops by 10% or more from daytime (awake) BP.
- ABPM.
Lifestyle Modifications.
Lifestyle modifications are directed toward reducing the patient’s BP and overall cardiovascular risk. Modifications include?
(1) weight reduction
(2) Dietary Approaches to Stop Hypertension (DASH) eating plan
(3) dietary sodium reduction
(4) moderation of alcohol intake
(5) regular physical activity
(6) avoidance of tobacco use (smoking and chewing)
(7) management of psychosocial risk factors
DASH Eating Plan.
1) The DASH eating plan emphasizes?
2) Compared with the typical American diet, the plan contains?
3) The DASH eating plan significantly lowers BP, and these decreases compare with those achieved with BP-lowering medication. Additional benefits also include lowering of?
1) fruits, vegetables, fat-free or low-fat milk and milk products, whole grains, fish, poultry, beans, seeds, and nuts.
2) less red meat, salt, sweets, added sugars, and sugar-containing beverages.
3) low-density lipoprotein (LDL) cholesterol
Hypertension Collaborative Care
Overall goals
- Control blood pressure
- Reduce CVD risk factors and target organ disease