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Nutrition for Nurses

11.1 Assess and Analyze the Impact of Nutrition on the Cardiovascular System

Nutrition for Nurses11.1 Assess and Analyze the Impact of Nutrition on the Cardiovascular System

Learning Outcomes

By the end of this section, you should be able to:

  • 11.1.1 Recognize cues that indicate the impact of nutrition on the cardiovascular system.
  • 11.1.2 Analyze cues to determine the impact of nutrition on the cardiovascular system.

Normal Function of the Cardiovascular System

The cardiovascular system includes the heart, blood, blood vessels, lymph, lymphatic vessels, and glands that move blood and lymph through the body. Assessment of this system involves the mechanical and electrical functions of the heart and blood vessels and their effectiveness at circulating blood throughout the body. Assessment should also include an examination of a client’s nutritional status.

The cardiovascular system’s primary role is to circulate blood throughout the body. The components of this system include the heart, known as the cardiac muscle, and blood vessels. The blood vessels include the arteries, which carry oxygenated blood from the heart to other parts of the body; veins, which carry deoxygenated blood from the body to the heart; and capillaries, tiny blood vessels with thin walls where arteries and veins exchange blood supply.

The heart has two components—the electrical conduction system and the mechanical working component—that work together to effectively pump blood and maintain proper perfusion, or movement of blood, oxygen, and nutrients to tissues in the body. The electrical system sends an impulse to the excitable cardiac tissue cells and triggers them to mechanically contract in a specific pattern to push blood throughout the body.

Nutrition can heavily impact the heart’s ability to complete the task of pumping blood. Like other muscles in the body, the heart requires electrolytes to produce action-potential impulses in muscles. The electrical charge that sends an impulse to the heart to trigger contraction is highly dependent on the involuntary process of potassium and sodium ion exchange (Balchem, 2021). Likewise, muscles, including the heart, are dependent on calcium and magnesium ion exchange for physical contraction or movement (Balchem, 2021). Low levels of these electrolytes can result in dysrhythmias and ineffective cardiac output and perfusion.

For the mechanical working component of the heart to function properly, the cardiac muscle must be supplied with oxygen and nutrients from the coronary arteries. The cardiac muscle must also be in good physical working condition and able to receive impulses from the heart’s electrical conduction system. The mechanical working component is not necessary for the electrical conduction system to function; but, without the mechanical working component, no blood is pumped through the body—and if the electrical conduction system is functioning independently, there will only be pulseless electrical activity (PEA), or electrical conduction throughout the heart without physical movement of the heart muscle.

Another consideration is the vascular portion of the cardiovascular system. While the heart requires electrolytes to create electrical impulses to trigger contractions strong enough to circulate blood throughout the body, it may still be unable to adequately perfuse the body if the vessels are blocked or become hardened, as in arteriosclerosis. The primary cause of this disease is a nutritional intake high in unhealthy fats and cholesterol. When low-density lipid (LDL) cholesterol levels are chronically high, fatty deposits known as plaques form in artery walls and reduce blood flow through that vessel (Icahn School of Medicine at Mount Sinai, 2023). When the heart is forced to push against the increased pressure from the less-elastic and smaller diameter of the diseased vessels, it causes the heart muscle to continually be overworked. The heart muscle can become damaged, and the eventual result can be heart failure.

The other consideration in normal function of the heart is the pressure it exerts against the vessel walls when contracting and relaxing, known as blood pressure. When blood pressure is chronically high, the client has an increased risk of heart failure. Blood pressure is largely regulated in the body by the renin-angiotensin-aldosterone system (RAAS) that utilizes fluid and electrolytes, especially sodium (Martyniak and Tomasik, 2022). This system works to change the sodium concentration in the blood to raise or lower blood pressure as needed by the body (Martyniak and Tomasik, 2022). When the concentration of sodium is chronically high due to excessive intake and is not able to be excreted by the kidneys, the RAAS system is unable to adequately control blood pressure.

There are two main circulatory systems of interconnected blood vessels that flow through the body: the systemic circulatory system and the pulmonary circulatory system. The systemic system provides blood to the body’s tissues, organs, and cells, and the pulmonary system transports blood between the heart and lungs allowing for oxygen and carbon dioxide exchange to occur (Sherrell, 2021).

Through the circulation of blood, the cardiovascular system performs several other functions. Blood is considered a “fluid connective tissue” (Visible Body, 2023), and it supports, protects, and gives structure to the blood vessels. Blood provides numerous other functions, including:

  • Clotting for tissue repair
  • Protection from infection
  • Transportation of body wastes to the kidneys for excretion
  • Exchange of oxygen and carbon dioxide between body tissues
  • Regulating body temperature
  • Transporting nutrients and hormones throughout the body for use and functional regulation (American Society of Hematology, 2023)

Assessment of Nutrition and the Function of the Cardiovascular System

A thorough assessment of the nutritional status of a client’s cardiovascular system involves examining each component. Many diseases are associated with poor nutrition or malnutrition. The most effective method of determining whether nutrition is a contributing factor is to evaluate each component individually. Note that the electrical conduction system and the mechanical working component should be assessed separately.

Assessing Electrical Conduction System of the Heart

The normal electrical pattern of the heart (Figure 11.2) starts with the initiation of an impulse at the sinoatrial node (SA node), the pacemaker of the heart. The impulse then travels through the atria, the top two heart chambers, causing atrial contraction, down to the atrioventricular node (AV node), an electrical gatekeeper that controls a delay between the atrial and ventricular impulse, allowing blood to fill the ventricle. From the AV node, the impulse travels to the bundle of His, a bundle of conducting fibers that branch to each ventricle, then down both bundle branches to the Purkinje fibers, or terminal-conducting fibers in the ventricles. This action causes the ventricles, or bottom chambers of the heart, to contract (Johns Hopkins Medicine, 2023b).

The path of electrical impulses through the heart is shown.
Figure 11.2 The heart muscle and systemic circulation are vital components that work together to deliver oxygen and nutrients to the body’s tissues and organs while removing waste products. (credit: modification of work from Anatomy and Physiology 2e. attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

An Electrocardiogram (ECG/EKG) or telemetry can be used to evaluate the electrical conduction of the heart. An ECG is a recording of a heart’s electrical activity through electrodes placed on the chest to capture signals. Telemetry is the continual measurement of a heart’s ECG through a portable device that automatically transmits the reading to a monitor.

A nurse should know several important measurement facts of a telemetry wave (Figure 11.3):

  • Each small square on the telemetry strip represents 0.04 seconds.
  • Each portion of the wave indicates a different part of the cardiac polarization (relaxation) and depolarization (contraction) cycle.
  • Each wave is expected to have a certain appearance or shape and specific deflection: positive being upward and negative being downward.
An example of an EKG recording shows the telemetry wave measurements. The reading is divided into the PQ and QT intervals. Points along the EKG are labeled O, P wave, Q, R, S, T wave, and U.
Figure 11.3 Nurses are expected to be able to measure and interpret the points of a telemetry wave. (credit: modification of work from Anatomy and Physiology 2e. attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

For the heart to be in optimal health, the electrical conductivity should be a normal sinus rhythm (NSR). An NSR is a rhythm that originates from the sinus node and is characteristic of a healthy heart’s cardiac rhythm. With an NSR, the wave tracing should be within normal measurements, and the deflections and appearances or shapes of all wave components should have a pulse that is calculated between 60 and 100 beats per minute. In addition, the waves should be consistent and resemble each other. Table 11.1 outlines the telemetry wave components, normal measurement, existence in the cardiac cycle, and the expected shape and deflection.

Wave/Segment Normal Measurement of Segment Part of Cardiac Cycle Wave/Segment Appearance/Shape and Deflection
P Atrial depolarization Positive deflection/smooth hill shape
Q Start of ventricular depolarization Negative deflection/sharp downstroke if shown (Some normal telemetry readings do not have a true Q wave.)
R Ventricular depolarization Positive deflection/sharp mountain peak upward
S Ventricular depolarization Negative deflection/sharp downward end of the mountain
T Ventricular repolarization Positive deflection/ smooth hill shape
U Atrial repolarization: not an expected finding on every client Positive deflection/smooth hill shape (Most normal telemetry readings do not have a U wave.)
QRS complex 0.06–0.12 seconds Ventricular depolarization Cluster of QRS waves together
PR interval 0.12–0.20 seconds Beginning of atrial depolarization to beginning of ventricular depolarization P wave and segment between P wave and Q wave
QT interval 0.40–0.44 seconds Beginning of ventricular depolarization through ventricular repolarization QRS complex, ST segment, and to end of T wave
ST segment Isoelectric line, not measured separately Time in-between ventricular depolarization and repolarization End of ST segment to beginning of T wave—must be on isoelectric line, no deflection
Table 11.1 Normal Telemetry Parameters (source: UNC Eshelman School of Pharmacy, 2023)

There are certain telemetry changes in which nutritional issues and electrolyte abnormalities are often the primary cause. Common examples include:

  • Long QT syndrome—when the QT interval is greater than 0.47 seconds in males and 0.48 seconds in females. This can lead to life-threatening dysrhythmias and can be caused by low levels of potassium, magnesium, or calcium.
  • Torsades de pointes—a life-threatening dysrhythmia known as a multifocal ventricular tachycardia, caused by low levels of magnesium (Cohagan & Brandis, 2022).
  • A peaked or mountain T wave illustrates hyperkalemia (high levels of potassium in the blood) (Bord, 2022).

Assessing the Mechanical Working Component of the Heart and the Blood Vessels

A healthy heart represents the flow of an adequate blood supply, proper stimulation through the electrical system, and effectiveness at physically pumping blood through the body. Normal blood flow through the heart starts when deoxygenated blood is returned to the heart from the body via the superior vena cava. It travels through the right atrium, through the tricuspid valve, and into the right ventricle. The blood is then pumped through the pulmonary valve and into the pulmonary artery to be re-oxygenated in the lungs (Figure 11.4). Once the blood has gone through the exchanges needed and is oxygenated, it returns to the heart through the pulmonary veins into the left atrium. It will then travel through the mitral valve into the left ventricle, through the aortic valve into the aorta, and out to the body for use (Pediatric Heart Specialists, 2023).

A diagram of the heart shows how deoxygenated blood flows into the heart, is re-oxygenated in the lungs, and then out to the body for use.
Figure 11.4 Normal blood flow starts when deoxygenated blood is returned to the heart via the superior vena cava. It travels through the right atrium, through the tricuspid valve, into the right ventricle, and is pumped through the pulmonary valve and into the pulmonary artery to be re-oxygenated in the lungs. (credit: modification of work from Anatomy and Physiology 2e. attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

The oxygenated blood is returned to the body through two types of arteries. Elastic arteries are located closer to the heart and are more flexible than muscular arteries. Muscular arteries contain smoother muscle and are farther away from the heart. Both types of arteries must have strong walls, because arteries handle higher pressures from the blood being pumped out of the heart (Cleveland Clinic, 2023b). The main function of arteries is to distribute the oxygenated blood to all body organs and tissues, including the heart itself, through the coronary arteries. Refer to Figure 11.5 for a visual of the artery wall.

The artery wall consists of the tunica externa, tunica media, tunica intima, smooth muscle, internal elastic membrane, vasa vasorum, external elastic membrane, nervi vasorum, endothelium, and elastic fiber.
Figure 11.5 The walls of elastic and muscular arteries must be both strong and flexible to properly handle high-pressure blood flow. (credit: modification of work from Anatomy and Physiology 2e. attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

As blood travels through the body via the arteries, the arteries get smaller in diameter until they terminate into arterioles, the smallest arteries. These arterioles link with capillaries and then connect to venules, the smallest veins (Gupta and Shea, 2022). Capillaries are thin-walled vessels that connect arterioles and venules. As shown in Figure 11.6, they are the vehicle for the final exchange of oxygen and nutrients into tissues and wastes into the blood (Gupta & Shea, 2022).

Blood from the heart flows into the arteriole and then the capillary. There, it exchanges oxygen and nutrients into the tissues and wastes into the blood. Once this occurs, blood flows into the veins where it travels back to the heart.
Figure 11.6 Capillaries connect arterioles and venules, and are the vehicle for the final exchange of oxygen and nutrients into tissues and waste into the blood. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

After passing through the capillaries and venules, blood continues into the veins on the way back to the heart. Veins have thinner walls than arteries, because pressures are lower in this portion of the cardiovascular system. Veins also dilate in response to fluid. Some veins, like the large veins in the legs, have valves in them to prevent backflow of blood (Gupta & Shea, 2022). Once blood has traveled through the veins, it ends up in the heart to start the cycle all over again.

Assessment

The nurse should complete a client’s assessment by recording manual blood pressure and apical pulse (a pulse point on the chest at the apex of the heart). In addition, the nurse should look for other signs and symptoms of adequate perfusion, including:

  • Quality and rate of peripheral pulses (carotid auscultation and palpation, brachial, radial, ulnar, femoral, popliteal, and pedal)
  • Skin color check for pallor or cyanosis
  • Skin temperature for degree of warmth and presence of moisture (Malik & Goyal, 2022)
  • Skin turgor (elasticity) to check for edema and venous stasis sores or discoloration
  • Capillary refill, which should be less than 2 seconds

Abnormal findings and their relationship to specific nutritional deficiencies are discussed in the next section.

Unfolding Case Study

Part A

Read the following clinical scenario and then answer the questions that follow. This case study will evolve throughout the chapter.

Mr. Thompson reports to the provider and nurse that he has had difficulty achieving and maintaining an erection and has noticed worrisome leg swelling. He also states that he was told by a nurse at a health fair a month ago that he should have his blood pressure checked, because it was 139/93 mm Hg. Today his blood pressure is 126/88 mm Hg. The swelling in his legs appears to be dependent edema that is only present when his legs are downward for periods of time and appears to be due to insufficiency of blood return in the lower extremities.

1.
Based on these findings, what would the nurse expect the provider to conclude?
  1. The client has an elevated blood pressure, peripheral arterial disease, and erectile dysfunction.
  2. The client has hypertension, peripheral arterial disease, and erectile dysfunction.
  3. The client has hypertension, peripheral vascular disease, and erectile dysfunction.
  4. The client has elevated blood pressure, peripheral vascular disease, and erectile dysfunction.
2.
Which of the following tests would the nurse expect the provider to order initially to evaluate heart function?
  1. Electrocardiogram
  2. Echocardiogram
  3. Troponin
  4. Chest X-ray

The provider orders an ECG that is done at bedside and shows no abnormalities. The provider also orders a fasting lipid panel (serum cholesterol levels) to help determine the client’s risk for heart disease. Because Mr. Thompson is not fasting, the provider instructs him to return in the morning for a blood draw and to return in one week for follow-up. The provider also explains to Mr. Thompson that erectile dysfunction can be directly related to the decreased blood flow caused by hypertension. The client’s hypertension will have to be managed before the erectile dysfunction can be fully evaluated for cause.

(source: Antipolis, S. (2020). How to Treat High Blood Pressure Without Ruining Your Sex Life. European Society of Cardiology. Retrieved from https://www.escardio.org/The-ESC/Press-Office/Press-releases/how-to-treat-high-blood-pressure-without-ruining-your-sex-life)

Analysis of Nutrition and the Cardiovascular System

A client’s nutritional status and needs can be identified with a physical assessment and lab results. Potassium, cholesterol, and sodium levels can be monitored to best track nutritional needs for cardiovascular health.

Nutritional Analysis and the Impact on the Cardiovascular System

Nutritional issues can lead to changes in the electrical conduction of the heart. As a result, the client’s telemetry rhythm can become abnormal. Rhythm changes include atrial fibrillation, atrial flutter, T-wave abnormalities, ST segment changes related to AMI, U-wave presence or prominence, torsades de pointes, prolonged QT interval, and supraventricular tachycardia. Rhythm changes can relate to one or more deficiencies. See Table 11.2 for a list of telemetry changes, the nutritional relation, and client symptoms.

Telemetry Change Nutritional Relation(s) Client Symptom(s)
Atrial fibrillation/atrial flutter
  • Excessive caffeine or alcohol intake
  • High cholesterol levels
  • High blood pressure
  • Palpitations
  • Lightheadedness
  • Chest pain
  • Extreme fatigue
  • Shortness of breath
Torsade de pointes
  • Primarily magnesium deficiency
  • Can be related to calcium deficiency
  • Can be related to magnesium deficiency
  • Can be related to potassium deficiency
  • Can start with syncope (fainting), palpations, and dizziness
  • Cardiac arrest
Supraventricular tachycardia
  • Excessive caffeine or alcohol intake
  • Heart disease (high cholesterol, obesity, or blood pressure)
  • Palpitations
  • Pounding sensation in the neck
  • Weakness
  • fatigue
  • Chest pain
  • Lightheadedness
  • Shortness of breath
  • Sweating
  • Dizziness
  • Fainting
T-wave changes
  • Inverted T waves can relate to cardiac ischemia from heart disease and/or past acute myocardial infarction (AMI) (triggered by high cholesterol and high blood pressure)
  • Peaked T waves can indicate hyperkalemia
  • Symptomology related to cause and type of change
U-wave presence/prominence
  • Hypokalemia (low potassium levels) can cause tachycardia and U-wave prominence
  • No symptomology unless it interferes with perfusion
ST segment changes/AMI
  • AMI can result from high cholesterol, obesity, and old ischemia damage to the heart
  • Chest pain
  • Cardiac arrest
  • Diaphoresis
  • Shock
  • Radiating pain to left jaw and shoulder
  • Shortness of breath
  • Weakness
  • Lightheadedness
  • Syncope
  • Pain in one or both arms and/or shoulders
QT interval
  • Shortened QT intervals can indicate hyperkalemia
  • Can trigger a lethal heart rhythm
Many other rhythm disturbances
  • Hyperkalemia can cause wide QRS complexes and hidden P waves, prolonged PR interval, decreased P wave amplitude, ventricular fibrillation, asystole, junctional rhythm, bradycardia, ST depression, atrial fibrillation, in addition to other issues listed
  • Hypoalbuminemia can cause low-voltage wave measurements and abnormal QT interval measurements and has been identified as a factor to increase mortality in AMI, atrial fibrillation events, and heart failure
  • Symptomology related to cause and type of change
Table 11.2 Nutritional Relationship to Rhythm Changes (sources: Akbar et al., 2022; Centers for Disease Control and Prevention, 2022; Cleveland Clinic, 2022a; Cleveland Clinic, 2022c; Cohagan & Brandis, 2022; Kenny & Brown, 2022; Lee, et al., 2022; Mayo Clinic, 2023a–b; Morales-Brown, 2020; Teymouri, et. al., 2022)

Numerous nutritional factors create or impact cardiovascular diseases such as coronary heart disease, cardiomyopathy (a disease of the heart muscle), and hypertension. Table 11.3 outlines a handful of cardiovascular diseases, the impact of nutrition, and the effect on the body.

Disease Nutrition Impact Effects on the Body
Coronary artery disease (CAD) Dietary intake that is high in cholesterol,
sodium, trans fats, added sugars, and low potassium and high
fluid intake (for CHF and cardiomyopathy
and especially with increased sodium specifically)
Can lead to hypertension, cardiomyopathy, and AMI
Peripheral vascular disease (PVD) Slows return of blood to the heart, leading to pooling of deoxygenated blood in the lower extremities
Peripheral arterial disease (PAD) Slows flow of blood to the body causing ischemia
Chronic heart failure (CHF) Causes weakening of the heart muscle
Cardiomyopathy Causes enlargement and weakening of the heart muscle
Hypertension Increases workload on the heart leading to cardiomyopathy and CHF
Table 11.3 Cardiovascular Diseases (sources: Albakri, 2019; Centers for Disease Control and Prevention, 2022; Harvard University, 2023; Medline Plus, 2022)
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