18.1 Hypertension and Angina

Hypertension

The cardiovascular system transports blood and oxygen throughout the body. Blood flows from a system of higher resistance to one of lower resistance—from arteries to capillaries to veins. Blood pressure (see Figure 18.2) represents the force that blood flow exerts on arterial walls.

Figure 18.2 The walls of the arteries are much thicker than those of the veins because of the higher pressure of the blood that flows through them. (credit: modification of work from Anatomy and Physiology 2e. attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

The two elements that determine blood pressure are cardiac output and peripheral vascular resistance. Cardiac output (CO) is the volume of blood pumped by the heart per unit of time, usually measured in liters per minute. The CO is determined by the heart rate (HR), the number of times the heart beats per minute, and stroke volume (SV)—the amount of blood ejected with each heartbeat—and is represented by the following equation: $\mathrm{CO}=\mathrm{HR}\times \mathrm{SV}$.

Blood pressure is determined by examining both systolic and diastolic blood pressure readings. The systolic blood pressure reading represents the amount of pressure within the arteries when the heart contracts, whereas the diastolic blood pressure reading reflects the amount of pressure when the heart is at rest between beats. The diastolic blood pressure reading, which is the lower pressure within the arteries and vessels, determines the peripheral vascular resistance (also known as systemic vascular resistance) by measuring blood flow and the level of constriction or dilatation within the arteries and vessels. Blood pressure (BP) is measured in millimeters of mercury (mm Hg) and is expressed as the systolic pressure over the diastolic pressure (for instance, 125/90 mm Hg).

Hypertension occurs when an individual’s blood pressure is above normal limits for a sustained period of time. Hypertension can be either primary (essential) hypertension or secondary hypertension. Primary hypertension is caused by unknown elements; however, some studies have implicated genetics and behavioral and environmental factors, including age, high salt intake, insulin resistance, obesity, high alcohol intake, sedentary lifestyle, smoking, and stress (Aggarwal et al., 2023; Iqbal & Jamal, 2022). According to the Centers for Disease Control and Prevention (n.d.), approximately 116 million adults in the United States have hypertension.

Importantly, hypertension is not limited to adults; it can also affect children and adolescents. In the United States and other countries, primary hypertension affects up to 5% of individuals in this younger age group. Developing high blood pressure during childhood can have long-term consequences, potentially leading to hypertension in adulthood and increasing the risk of heart disease, stroke, and kidney damage. Certain modifiable risk factors can be addressed for this population to improve blood pressure levels, including obesity, physical activity, and nutrition. Health care providers should always assess blood pressure in the pediatric population to promote preventive measures within families and foster healthy lifestyle habits (American Heart Association, 2023).

Secondary hypertension results from other conditions involving the central nervous system, endocrine system, and renal system and is treated along with the underlying condition. Secondary hypertension may be cured if the treatment for the underlying condition is successful.

Hormones also impact blood pressure regulation. The Renin-angiotensin-aldosterone system (RAAS) and vasopressin are the main physiologic regulatory systems or pathways affecting blood pressure homeostasis. RAAS, as illustrated in Figure 18.3, is a compensatory mechanism the body activates during hypotension (when blood pressure is low). Renin is released from the kidneys in response to low blood pressure. Renin interacts with angiotensinogen and converts it to angiotensin I. The angiotensin-converting enzyme in the pulmonary blood vessel endothelium is then triggered to produce angiotensin II, which constricts arterioles, increasing peripheral resistance and increasing blood pressure. Angiotensin II also stimulates the adrenal medulla to produce catecholamine, which yields aldosterone. Aldosterone causes the kidneys to retain water and sodium, which leads to water retention and results in an increased blood volume, cardiac output, and blood pressure. Vasopressin is an antidiuretic hormone that regulates reabsorption of water by the kidneys; it is released by the pituitary gland in response to low blood volume. Vasopressin causes retention of body fluids, vasoconstriction, and increased blood pressure.

Figure 18.3 The renin-angiotensin-aldosterone system (RAAS) is a compensatory mechanism the body activates when blood pressure is low. (credit: modification of work “Overview of the renin-angiotensin system” by Mikael Häggström/Wikimedia Commons, Public Domain)

Nonpharmacologic Treatment for Hypertension

Nonpharmacologic measures used to treat hypertension center around lifestyle changes. Lifestyle changes focus on the client’s personal, social, and cultural influences. These changes may include diet modification, increased physical activity and exercise, smoking cessation, alcohol consumption reduction, relaxation techniques, and self-monitoring.

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Dietary Modification

Clients with hypertension should eat a low-sodium diet consisting of whole grains, vegetables, and fruits. Other recommendations include low-fat dairy products and limiting meat intake to about two servings daily of lean meat, such as fish and poultry (Challa & Ameer, 2023). Reducing sweets and red meat is also important. The AHA (n.d.-b) recommends 1500 mg to no more than 2300 mg of sodium intake daily. Dietary patterns and nutritional therapy should focus on food preferences, social and cultural influences, and appropriate caloric intake.

Physical Activity and Exercise

The AHA (n.d.-d) recommends 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous aerobic activity weekly. Average time for exercise should be at least 30–40 minutes per session to assist in decreasing blood pressure. If the client cannot do 30–40 minutes of moderate exercise four times a week, the nurse should suggest an alternate exercise plan, emphasizing that some physical activity is better than no physical activity. Physical activity and exercise enhance weight reduction and promote a healthy lifestyle.

Smoking Cessation and Reducing Alcohol Consumption

Tobacco use is the leading preventable cause of coronary artery disease. Smoking increases sympathetic nervous system activity, which causes vasoconstriction and, therefore, increases blood pressure, heart rate, and myocardial contractility. Although smoking has been established as a known risk factor for cardiovascular disease, its relationship to high blood pressure is still being investigated. Nevertheless, smoking and exposure to secondhand smoke contribute to increased accumulation of fatty deposits within the arteries, which high blood pressure is known to accelerate (AHA, n.d.-c).

Alcohol consumption increases blood pressure by increasing the level of the hormone renin in the blood. Renin decreases fluid elimination, causing higher fluid volume in the body and arterial vasoconstriction that results in an increase in blood pressure. Reducing alcohol consumption has been shown to decrease systolic and/or diastolic blood pressure by 5–12 mm Hg (Wake, 2021).

Relaxation Techniques

According to Harvard Health Publishing (2022), meditation has been associated with reducing blood pressure. Herawati et al. (2023) adds that slow breathing can be used as a nonpharmacological treatment to lower blood pressure. The National Center for Complementary and Integrative Health (2021) reviewed research on relaxation and blood pressure control that showed relaxation techniques resulted in small reductions in blood pressure and demonstrated yoga may be used as an adjunct intervention for the management of hypertension.

Clinical Tip

Assessing Client Lifestyle Modifications

The nurse should work closely with the client to promote lifestyle changes—such as diet modifications and weight loss, increase in exercise, smoking cessation, and use of relaxation techniques—that will improve baseline blood pressure readings.

Self-Monitoring of Hypertension

Home blood pressure monitoring (Figure 18.4) contributes to the comprehension of hypertension and facilitates the awareness of the importance of blood pressure management. Clients are now able to monitor their blood pressure with electronic blood pressure devices. Home blood pressure monitoring leads to awareness of one’s blood pressure, better blood pressure control, and adherence to lifestyle changes and drug therapies (Verma et al., 2021).

Figure 18.4 Daily blood pressure monitoring at home allows clients to better manage their blood pressure. (credit: “Arm Band Blood Pressure Monitor” by Alabama Extension/Flickr, Public Domain)

Angina

Angina (also called angina pectoris) is characterized by discomfort in the front of the chest, neck, shoulders, jaw, or arms that is precipitated by physical exertions and relieved by rest within 5 minutes or sublingual nitrates (Ueng et al., 2023). Angina is caused by reduced blood flow to the heart. The four types of angina (AHA, 2022a) are:

• Stable angina is the most common form. It often occurs during activity and may sometimes occur at rest. Stable angina is predictable and follows a pattern of similar episodes of chest pain.
• Unstable angina is unpredictable and considered a medical emergency. Unlike stable angina, unstable angina usually occurs during rest and does not follow a pattern of similar episodes of chest pain; episodes may last longer than stable angina episodes. If blood flow to the heart does not improve, a myocardial infarction (heart attack) may occur.
• Variant (Prinzmetal) angina, unlike the other forms of angina, is not caused by coronary artery disease but rather by a spasm in the heart’s arteries that temporarily decreases blood flow and almost always occurs at rest.
• Microvascular angina is frequent episodes of angina that occur due to coronary microvascular disease.

Risk factors for stable, unstable, and microvascular angina include age, family history, tobacco use, diabetes, hypertension, high cholesterol, obesity, and metabolic syndrome. Risk factors for Prinzmetal angina may be caused by anything that leads to spasms of the coronary arteries including certain medications such as decongestants, use of substances such as cannabis and cocaine, smoking tobacco, and stress (AHA, 2022a).