NCLEX: Care of the Client with Cardiovascular Disorders

Focus topic: Care of the Client with Cardiovascular Disorders

The cardiovascular system comprises the heart and blood vessels and is responsible for the transport of oxygen and nutrients to the organ systems of the body. The heart is a cone-shaped organ made up of four chambers. The right atrium receives blood from the venous system by way of the superior and inferior vena cavae. Most of the venous blood flows through the tricuspid valve and into the right ventricle during the filling phase of cardiac contraction.

The blood then moves to the lungs where carbon dioxide is released and oxygen is taken on. The left side of the heart then pumps the oxygenated blood to the body. During systole, the pressure exerted on the ventricle closes the mitral valve to prevent blood from flowing backward into the left atrium and opens the aortic valve to assist the ventricle to pump adequate oxygenated blood out of the heart into the aorta and to the body. Arteries and veins are types of blood vessels. Arteries transport oxygenated blood, and veins transport deoxygenated blood.

On this category, you will discover diseases that affect the cardiovascular system, treatment of these diseases, and their effects on the client’s general health status.
Care of the Client with Cardiovascular Disorders

Anatomy of the human heart

 

Care of the Client with Cardiovascular Disorders: Hypertension

Focus topic: Care of the Client with Cardiovascular Disorders

Blood pressure is the force of blood exerted on the vessel walls. Systolic pressure is the pressure during the contraction phase of the heart and is the top number of a blood pressure reading. Diastolic pressure is the pressure during the relaxation phase or filling phase of the heart and is the bottom number of a blood pressure reading. Factors that alter peripheral resistance, heart rate, and stroke volume affect the blood pressure. Hypertension is defined as a systolic blood pressure greater than or equal to 140 over 90 mm Hg.

If the client has diabetes or kidney disease, a systolic blood pressure greater than 130 mm Hg systolic and a diastolic blood pressure of 80 mm Hg or higher is considered hypertension and should be treated. The autonomic nervous system and circulating blood volume control blood pressure. Blood pressure also directly relates to circulating hormones such as anti-diuretic hormones.

Hypertension is classified as either primary or secondary. Primary or essential hypertension develops without apparent cause; secondary hypertension develops as the result of another illness or condition. Some examples of diseases that result in secondary hypertension are diabetes, peripheral vascular disease, renal disease, preeclampsia, coarctation of the aorta, adrenal tumors such as pheochromocytomas, brain tumors, encephalitis, and primary aldosteronism.

This and other chapters of the book discuss these diseases. Obesity and smoking also affect blood pressure. Appropriate treatment of the contributing illness improves the symptoms associated with secondary hypertension.

Malignant hypertension is an extremely elevated blood pressure that often results in a cerebral vascular accident or a myocardial infarction. Secondary hypertension occurs when another disease process causes the blood pressure to elevate above normal limits. Many medications can lead to secondary hypertension. Some examples of medications that can lead to hypertension are NSAIDs (nonstreroidal anti-inflammatory drugs), cocaine, amphetamines, bronchodilators, and estrogen preparations.

The client might complain of a headache, blurred vision, and dyspnea. If renal function is impaired, the client will exhibit signs of uremia. A systolic blood pressure greater than 200 mm Hg and a diastolic blood pressure greater than 150 mm Hg is life-threatening. To prevent further deterioration of the client’s condition, medical personnel must implement prompt intervention.

Care of the Client with Cardiovascular Disorders: Diagnosing the Client with Hypertension

Focus topic: Care of the Client with Cardiovascular Disorders

The accuracy of a BP reading depends on the correct selection of cuff size. The bladder of the blood pressure cuff size should be sufficient to encircle the arm or thigh. According to the American Heart Association, the bladder width should be approximately 40% of the circumference or 20% wider than the diameter of the midpoint of the extremity.

A too-small blood pressure cuff yields a false high reading, whereas a too- large blood pressure cuff yields a false low reading. For accuracy, the arm being used to check the blood pressure should be held at the level of the heart.

The blood pressure should be taken on at least two occasions sitting, standing, and in a supine position. Diagnosis of hypertension involves conducting a comprehensive history of illness and stressors in the client’s life and medications taken by the client. Laboratory studies must be completed to determine any underlying illness that might be present. Some laboratory studies indicate the presence of protein in the urine.

Others studies measure serum creatinine levels, blood urea nitrogen, serum corticoids, and 17-ketosteroids in the urine. The presence of serum corticoids and 17-ketosteroids in the urine is diagnostic of Cushing’s disease or increased function of the adrenal glands.

A radiography study, such as an intravenous pyelography (IVP), can confirm renal disease. X-rays and computer tomography (CT) scans to determine the presence of tumors might also be ordered. An electrocardiogram (ECG) is valuable in determining the extent of cardiovascular involvement. Ultrasounds of the kidneys or the presence of adrenal tumors can also assist the physician with making a diagnosis of secondary hypertension.

Care of the Client with Cardiovascular Disorders: Managing the Client with Hypertension

Focus topic: Care of the Client with Cardiovascular Disorders

Management of hypertension includes a program of stress reduction, diet, smoking cessation, and exercise. A diet low in sodium is suggested. If the client’s cholesterol level is elevated, a low-fat, low-cholesterol diet is ordered The National Cholesterol Education Program recommends screening guidelines based on

  • Total serum cholesterol and high-density lipoprotein (HDL) levels in persons that do not show signs of cardiac or peripheral vascular disease
  • Total serum cholesterol and HDL levels in clients with risk factors for heart disease

A desirable high-density lipoprotein level is above 40 mg/dL, and a desirable low- density lipoprotein (LDL) level is below 100 mg/dL. A triglyceride level of 150 mg/dl is considered normal. A triglyceride level of 200 mg/dL or higher indicates that the client is at risk for cardiovascular disease. Scientists recently found that homocysteine, a sulfur-containing amino acid derived from dietary protein, plays a part in the development of heart disease. A serum homocysteine level greater than 15 μmol/L is considered a risk factor.

Current studies show consumption of folic acid can help to lower homocysteine levels. Monounsaturated fats found in canola oil, olive oil, and nuts are high in polyunsaturated oils. These oils are recommended for individuals at risk for coronary disease. Eggs are saturated fats and should be limited by clients with risk for heart disease. The client is taught to avoid palm oil and coconut oil. If a change in diet does not lower the client’s cholesterol level, the doctor might prescribe hyperlipidemic medications such as simvastatin (Zocor), gemfibrozil (Lopid), or ezetimibe (Zetia).

If diet, weight control, and exercise are unsuccessful in controlling the client’s hypertension, the healthcare provider might need to treat the client with a diuretic and/or an antihypertensive medication. There are three types of diuretics. Thiazide diuretics such as hydrochlorothiazide (HCTZ) and Furosemide (Lasix), a loop diuretic, do not spare potassium.

The nurse should assess the client taking non–potassium-sparing diuretics for signs of hypokalemia. Potassium-sparing diuretics work by inhibiting the creation of antidiuretic hormone, thereby decreasing the amount of sodium ions. Diuretics are usually prescribed to be taken in the morning on a one-time-daily regime. Taking the diuretic in the morning allows the client to sleep comfortably during the night rather than experiencing nocturia (night-time voiding).

If diuretics alone are unsuccessful in lowering the blood pressure, the physician might need to add an antihypertensive medication. Beta-adrenergic blocking agents lower blood pressure by blocking the beta receptors. Bradycardia (a heart rate of less than 60 beats per minute) and congestive heart failure are possible complications of this type of medication.

The client should be taught to check his pulse rate daily and report bradycardia to the physician. Clients with a history of asthma taking beta-adrenergic agents should be watched for complications such as bronchospasms. Side effects include fatigue, weakness, sexual dysfunction, and depression. These drugs might be prescribed in combination with a diuretic.

Calcium channel blockers such as verapamil hydrochloride (Calan) lower the blood pressure by interfering with calcium ions. This reduction in calcium ions results in vasodilation.

 

 Care of the Client with Cardiovascular Disorders

 

Angiotensin-converting enzyme (ACE) inhibitors are also used alone or in combination with a diuretic. ACE inhibitors work by inhibiting angiotensin I to angiotensin II, a very potent vasoconstrictor. An example of an ACE inhibitor is lisinopril (Zestril). When the client starts taking an ACE inhibitor, he should be taught to remain in bed for three to four hours because it can cause initial postural hypotension in some clients. One of the most common side effects of ACE inhibitors is a chronic cough. If the client experiences chronic coughing, he should report it to the healthcare provider. Angioedema, a condition marked by the development of edematous and itching areas of the skin or mucous membranes and visceral edema, are signs of a reaction to the medication. If the client experiences signs of angioedema, the healthcare provider should be notified immediately.

Angiotensin II receptor antagonists block the binding of angiotensin II while allowing angiotensin-converting enzymes to function normally. This allows vasodilation to occur. An example of an angiotensin II receptor antagonist is losartan (Cozaar). They are an excellent choice for clients who experience a hacking cough when taking ACE inhibitors.

Central alpha adrenergic receptor blockers act on the central nervous system and prevent reuptake of norepinephrine. This results in vasodilation. Two examples of central apha agonists are clonidine (Catapres) and methyldopa (Aldomet). Male clients sometimes experience impotence when taking methyldopa (Aldomet). Anemia and liver dysfunction are possible complications of this category of medication.

Vasodilators such as Nitrobid and Nitropress relax and dilate smooth muscles, thereby causing a decrease in peripheral vascular resistance. Alpha-adrenergic receptor agonists dilate arterioles and veins, therefore lowering the blood pressure quickly. An example of this category of drugs is prazosin (Minipress). Most clients with essential hypertension require maintenance with medication and diet for the rest of their lives.

Care of the Client with Cardiovascular Disorders: Coronary Artery Disease

Focus topic: Care of the Client with Cardiovascular Disorders

Coronary artery disease (CAD) affects the arteries. When narrowing of the coronary arteries (the large arteries that supply the myocardium with blood) occurs, the result is ischemia. Narrowing of the coronary arteries is usually due to atherosclerosis.

Care of the Client with Cardiovascular Disorders: Atherosclerosis and Arteriosclerosis

Focus topic: Care of the Client with Cardiovascular Disorders

Though atherosclerosis and arteriosclerosis are related problems, they are not the same. Atherosclerosis is a type of arteriosclerosis involving cholesterol deposits and triglyceride deposits. Atherosclerosis is the overgrowth of smooth muscle cells. Narrowing of the blood vessels is the result of an overgrowth of intimal smooth muscle cells. This narrowing causes decreased blood flow to the heart and major organs. Arteriosclerosis is the thickening and hardening of the arterial walls.

Symptoms of arteriosclerosis and atherosclerosis include intermittent claudication, decreased circulation to the extremities, changes in skin color and coolness of the extremities, headaches, dizziness, and loss of memory. Factors that contribute to arteriosclerosis and atherosclerosis are age, obesity, cigarette smoking, diabetes, and familial predisposition. Treatment of systemic signs of arteriosclerosis involves weight control with a diet low in fats and cholesterol. Stress reduction and smoking cessation also help to decrease the client’s risk factors.

Care of the Client with Cardiovascular Disorders: Conduction System of the Heart

Focus topic: Care of the Client with Cardiovascular Disorders

The normal conduction system of the heart is composed of the sinoatrial (SA) node located at the junction of the right atrium and the superior vena cava. The SA node is the main pacer of the heart rate. This area contains the pacing cells that initiate the contraction of the heart. The atrioventricular (AV) node is located in the interventricular septum. The AV node receives the impulse and transmits it to the bundle of His, which extends down through the ventricular septum and merges with the Purkinje fibers in the lower portion of the ventricles.

 

 Care of the Client with Cardiovascular Disorders

Electrical system of the heart.

 

Care of the Client with Cardiovascular Disorders: Heart Block

Focus topic: Care of the Client with Cardiovascular Disorders

Heart block can occur as the result of structural changes in the conduction system (such as myocardial infarctions, coronary artery disease, tumors, and infections of the heart) or toxic effects of drugs (such as digitalis).

First-degree AV block occurs when the SA node continues to function normally but transmission of the impulse is slowed. Because of the conduction dysfunction and ventricular depolarization, the heart beats regularly but the P-R interval is slowed. These clients are usually asymptomatic, and all impulses eventually reach the ventricles.

Second-degree heart block is a block in which some impulses reach the ventricles but others do not.

In third-degree heart block or complete heart block, none of the sinus impulses reach the ventricle. This results in erratic heart rates in which the sinus node and the atrioventric- ular nodes beat independently. The result of this type of heart block can be hypotension, seizures, cerebral ischemia, or cardiac arrest. A heart block is detected by assessing an electrocardiogram.

Care of the Client with Cardiovascular Disorders: Toxicity to Medications

Focus topic: Care of the Client with Cardiovascular Disorders

Toxicity to medications such calcium chanel blockers, betablockers, or digitalis can be associated with heart block. Clients taking betablockers or digoxin (Digitalis) should be taught to check their pulse rate and to return to their physician for regular evaluations of their digitalis levels. Judicious monitoring of the digoxin (Digitalis) blood levels is an important factor in the care of the client. The therapeutic level for digoxin (Digitalis) is 0.9–1.2 ng/mL. If the client’s blood level of digoxin (Digitalis) exceeds 2.0 ng/mL, the client is considered toxic. Clients with digoxin toxicity often complain of nausea, vomiting, and seeing halos around lights.

A resting pulse rate of less than 60 bpm in an adult client, less than 80 bpm in a child, and less than 100 bpm in a neonatal client should alert the nurse to the possibility of toxicity. Treatment for digitalis toxicity includes checking the potassium level because hypokalemia can contribute to digitalis toxicity. The physician often will order potassium be given IV or orally and that the digitalis be held until serum levels return to normal. Another medication, such as Isuprel or atropine, is frequently ordered to increase the heart rate. A high-fiber diet will also be ordered because constipation contributes to digitalis toxicity.

Care of the Client with Cardiovascular Disorders: Malfunction of the Conduction System

Focus topic: Care of the Client with Cardiovascular Disorders

Because a malfunction of the conduction system of the heart is the most common cause of heart block, a pacing mechanism is frequently implanted to facilitate conduction. Pacemakers can be permanent or temporary and categorized as demand or set. A demand pacemaker initiates an impulse if the client’s heart rate falls below the prescribed beats per minute. A set pacemaker overrides the heart’s own conduction system and delivers an impulse at the rate set by the physician. Pacemakers can be combined with an internal defibrillation device.

 

 Care of the Client with Cardiovascular Disorders

Indicates the pacemaker spike with a normal ECG.

 

Care of the Client with Cardiovascular Disorders: Cardiac Monitoring

Focus topic: Care of the Client with Cardiovascular Disorders

An ECG provides a tracing of the heart’s electrical currents. Electrodes attach to the client’s chest with adhesive pads and then attach to cables (leads) connected to the electrocardiograph machine. Leads are made up of positive and negative electrodes. The relationship between the positive and negative electrodes is responsible for the deflections seen on the ECG machine.

The most commonly used ECG consists of 12 leads. Six leads are placed on the chest wall (V1–V6). These 6 leads provide a picture of the heart’s electrical activity from a variety of positions on the chest wall. The chest leads are placed on the horizontal axis of the chest. The limb leads are attached to the arms and legs. The client should be taught to remain as still as possible during ECG assessment and should be positioned in a semireclined position. For continuous ECG monitoring, the use of limb leads is not recommended because limb movement causes an inaccurate reading.

Continuous ECG readings are most commonly done using the modified chest lead (MCL) system, which incorporates only three leads. If only three leads are used the white electrode is placed just below the mid-clavicle area on the client’s right side, the black lead is placed below the mid-clavicle area on the client’s left side and the positive (red) is placed at the mid-clavicular region on the client’s left side.

If the six lead system is used the client is monitored using the V1 position located at the fourth intercostals position at the right sternal border. V2 is placed at the fourth intercostals space at the left sternal border. V3 is located midway between V2 and V4. V5 is located at the fifth intercostals space at the anterior axillary line. V6 is located at the fifth intercostals space at the midaxillary line. The ground electrode can be placed anywhere but is usually placed under the right clavicle. For accuracy of chest lead placement, the client’s chest hair should be clipped with scissors rather than shaved because shaving can abrade the skin.

 

 Care of the Client with Cardiovascular Disorders

Twelve-lead ECG electrode placement.

Care of the Client with Cardiovascular Disorders: Reading an Electrocardiogram

Focus topic: Care of the Client with Cardiovascular Disorders

The P wave represents atrial depolarization. P-R interval is the time required for the atria to depolarize and the impulse to travel through the conduction system to the Purkinje fibers. It is measured from the beginning of the P wave to the end of the P-R segment. The QRS complex represents the contrac- tion phase of the heart and is measured from the beginning of the Q wave or R wave to the end of the S wave. The T wave represents repolarization of the heart.

After you look at the ECG reading for the presence of the P wave, QRS complex, and T wave, you will want to start your evaluation of the heart rate. Measure the rate by counting the number of P-P intervals or R-R intervals on a 6-second ECG strip. Timing should begin with the P wave or the QRS complex and end 30 large blocks later. The heart rate can be determined by looking at a 6-second strip, counting the cardiac cycles and the number of QRS complexes, and multiplying by 10. This method provides an accurate rate analysis of whether the rate is regular or irregular.

 

 Care of the Client with Cardiovascular Disorders

A normal ECG.

 

A normal rhythm is one that originates in the SA node, is regular, has a rate of 60–100 beats per minute (bpm), has a P wave that is consistent, and is followed by a QRS complex. ECG tracing paper measures electrical impulses in duration of time. Each large block on the paper is 5 mm or 0.20 seconds and contains 25 small blocks. Each small block on the paper is 1 mm or 0.04 seconds. The normal ECG rhythm has a P-R interval of 0.12–0.20 seconds and has a QRS complex with a duration of 0.04–0.12 seconds.

Care of the Client with Cardiovascular Disorders: Cardiac Dysrhythmias

Focus topic: Care of the Client with Cardiovascular Disorders

Cardiac dysrhythmias occur when the heart loses its regular pacing capability. They are classified according to their origins. These abnormal rhythms can be lethal or of no danger to the client’s well-being. Tachydysrhythmias are characterized by a heart rate greater than 100 bpm. If the client has coronary artery disease, blood flow to the heart might be decreased. Bradydysrhythmias are characterized by a heart rate less than 60 beats per minute. Dizziness and syncopy are often the only symptoms the client notices.

The client might tolerate this slow rate, or bradydysrhythmias might cause the blood pressure to be subnormal, leading to shock or ischemia. Another alteration in the normal beat the client might experience is bigeminy, a condition in which arrhythmias occur in pairs. The pairs can be junctional, atrial, or ventricular beats. A junctional beat is one originating at the AV and bundle of HIS. An atrial dysrhythmia originates in the atria of the heart, while a ventricular dysrhythmia originates in the ventricle of the heart.

 

Supraventricular Rhythm Characteristics

 Care of the Client with Cardiovascular Disorders

 Care of the Client with Cardiovascular Disorders

Unlike tachydysrhythmias and bradydysrhythmias, which usually originate in the atria, ventricular dysrhythmias are life-threatening and their impulses originate in the ventricles.

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