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C h a p t e r C o n t e n t s
Introduction Anatomy of the Heart Blood’s Path Through the Heart Cardiac Cycle Heart Sounds Blood Pressure Common Cardiac Diseases and Treatments Diagnostic Studies and Procedures Chapter Summary
O b j e c t i v e s
After completing this chapter, you will be able to:
- Name and describe the anatomic structures of the heart and associated blood vessels.
- Explain cardiac conduction and describe the car- diac cycle.
- Discuss blood pressure measurement and how blood pressure readings are obtained.
- Describe common diseases and disorders related to the heart and their treatments.
- Discuss common laboratory tests and diagnostic studies used to identify heart disease.
CardiologyCardiology
INTRODUCTION
Cardiology is a medical speciality dealing with the diag- nosis and treatment of diseases and disorders of the heart. The term derives from the Latin word cardium , which is borrowed from the Greek word kardia. Cardium is used to describe the heart in other words using the combining forms card/i and cardi/o, such as cardiopul- monary (relating to the heart and lungs) and cardiovas- cular (relating to the heart and blood vessels or circula- tion). The heart is a complex organ that supplies the body with the blood and oxygen it needs to function properly. Relatively simple in function, the heart’s primary pur- pose is to pump blood, 24 hours a day, 70 to 80 times a minute. With each beat, the heart pumps blood that delivers life-sustaining oxygen and nutrients to 300 tril- lion cells. The rhythmic beating of the heart is a cease- less activity, beginning before birth and ceasing only at the end of life. The heart pumps blood through a closed circuit of vessels as it passes through the various areas of the body in a continuous loop. In this journey, blood containing oxygen and nutrients is pumped from the heart to every part of the body. On the way back to the heart, the blood picks up waste products for disposal by the kidneys and
other organs before entering the heart again for another trip. Although major advances have occurred in physi- cians’ understanding of the heart and ways to treat car- diac disorders, the workings of the heart and the dis- eases that affect it still present the medical profession with diagnostic and therapeutic challenges. This chapter reviews the structure and function of the heart, common diseases and disorders affecting heart function, and the clinical tests and procedures used to diagnose and treat heart disease.
ANATOMY OF THE HEART
The human heart is a four-chambered muscular organ that works to pump blood through the body. Although most of the hollow organs of the body do have muscular layers, the heart is composed almost entirely of muscle. Although it is convenient to describe the flow of blood through the right side of the heart and then through the left side, it is important to realize that the heart is actually two different, but anatomically con- nected, pumps that contract at the same time. The right side of the heart receives blood from the body and pumps it into the lungs to gather oxygen, whereas the left side receives the oxygenated blood from the lungs
and pumps it to the rest of the body, where oxygen and nutrients are delivered to tissues and waste products are transferred to the blood for removal by other organs (such as the kidneys). The heart is located in the middle of the chest, behind and slightly to the left of the sternum, and is composed of membranous layers, chambers, valves, and a variety of blood vessels, as shown in Figure 11.
Layers
A double-layered membrane called the pericardium surrounds the heart like a transparent sac. The outer layer of the pericardium is attached by ligaments to the spinal column, diaphragm, and other parts of the body. The inner layer of the pericardium is attached to the heart itself. Three layers of tissue form the heart wall: the outer layer of the heart wall is the epicardium , the mid- dle layer, or heart muscle itself, is the myocardium , and
the inner layer which lines the heart’s chambers and covers its valves is the endocardium.
Chambers Chambers are compartments of the heart through which blood flows. The internal cavity of the heart is divided into four chambers, two on the left and two on the right. Each of the two upper chambers is called the left and right atrium (plural, atria ). The atria serve as reservoirs for blood. Each atrium is connected by its own valve to a chamber below it. The two lower cham- bers are called the left and right ventricles which are responsible for collecting blood from the right and left atria and pumping it out of the heart. The left atrium and ventricle are responsible for receiving oxygen-rich blood from the lungs and pumping it throughout the body. The right atrium and ventricle are responsible for receiving deoxygenated blood from the various areas of
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Aortic arch
Aorta
Superior vena cava
Pulmonary veins
Atrial septum
Left ventricle
Aortic valve
Mitral valve
Left atrium
Ventricular septum
Pericardium
Epicardium
Myocardium
Endocardium
Tricuspid valve
Inferior vena cava
Deoxygenated blood
Oxygenated blood
Right ventricle
Pulmonary artery
Pulmonary semilunar valve
Right atrium
FIGURE 11.1. Anatomy of the heart. The red and blue arrows show the flow of oxygenated and de-oxygenated blood through the heart muscle. Reprinted with permission from Willis MC. Medical Terminology: A Programmed Learning Approach to the Language of Health Care. Baltimore: Lippincott Williams & Wilkins, 2002.
This condition is called a myocardial infarction (MI), or a heart attack.
BLOOD’S PATH THROUGH
THE HEART
Blood is carried into the heart through the several vessels, all of which empty into two major veins: the superior vena cava and the inferior vena cava. The superior vena
cava carries blood from the upper body to the right atrium (it is called superior because it means near the top ). The inferior vena cava carries blood from the lower body to the right atrium ( inferior means situated below ). Blood in the right atrium empties into the right ventricle. When the ventricle contracts, the blood is ejected into the pulmonary artery , the blood vessel that takes blood from the heart to the lungs. From the lungs, oxygen-rich blood travels to the left atrium through the pulmonary veins , the vessels responsible for carrying blood from the lungs to the heart. The left atrium empties blood into the left ventricle. The left ventricle pumps the blood into the aorta, and from there, it travels throughout the body.
CARDIAC CYCLE
Like all pumps, the heart requires a source of energy in order to function. The heart’s pumping energy comes from an electrical conduction system within the heart muscle. Cardiac conduction is the name given to the electrical conduction system that controls the heart rate. This system generates electrical impulses that cause the heart muscle to contract and relax, enabling it to pump blood throughout the body. This contracting and relax- ing of the heart muscle is a two-part pumping action commonly called a heartbeat. The cardiac cycle is the sequence of events in one heartbeat. Throughout the cardiac cycle, the right and left atria continuously accept blood returning to the heart from the body while the two ventricles push blood out of the heart to be circulated into the body. In its sim- plest form, the cardiac cycle is the simultaneous con- traction of the two atria, followed a fraction of a second later by the simultaneous contraction of the two ventri- cles. The cardiac cycle has two basic components: The contraction phase, called systole , occurs when blood is ejected from the chambers of the heart. The relaxation phase, called diastole , occurs when the heart is at rest and the chambers fill with blood in preparation for the next contraction. Figure 11.3 illustrates the process of the cardiac cycle. The electrical stimulus for the heart to pump begins with the sinoatrial (SA) node , a small mass of special- ized tissue located near the rear wall of the right atrium that causes the heart to beat. The SA node is often called the heart’s natural pacemaker because it sets the rate and rhythm of the heartbeat. The SA node generates an elec- trical impulse, which begins traveling down through the conduction pathways in the heart muscle, similar to the way electricity flows through power lines from a power plant. When this impulse fires, it spreads through the walls of the right and left atria, which are filled with blood. The impulse causes the atria to contract so that blood will flow from the atria into the ventricles.
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Aortic arch
Right coronary artery
Posterior descending coronary artery
Left anterior descending coronary artery
Left main coronary artery
Circumflex coronary artery
FIGURE 11.2. The coronary arteries and veins. Coronary arteries (in red) arise from the aorta and encircle the heart. Coronary veins (above) are shown in blue. Reprinted with permission from Smeltzer SC, Bare BG. Textbook of Medical-Surgical Nursing, 9th ed. Philadelphia: Lippincott Williams & Wilkins, 2000.
Transcription
Tip:
Listen for the abbreviation TIMI (pronounced like timmy ), when transcribing reports that describe the treatment of a patient with myocardial infarction. TIMI stands for t hrombolysis i n m yocardial i nfarction and is a grad- ing system (using grades 0 - 3 ) that refers to the reperfusion of blood flow achieved after the applica- tion of thrombolytic therapy. It is transcribed with lowercase grade , followed by an Arabic numeral. Example: “The patient achieved a TIMI grade 3 flow at 6 0 minutes following thrombolytic therapy.”
The impulse then travels to another section of nodal tissue called the atrioventricular (AV) node , which lies on the right side of the partition that divides the atria. Located near the center of the heart, the AV node is like a bridge between the atria and ventricles and serves as a kind of gatekeeper, delaying the electrical impulse from the atria for about one-tenth of a second before relaying it on to the ventricles. This pause is important because it permits the atria to complete their contraction and empty their blood into the ventricles. This allows the ventricles to fill before they contract, or open, releasing the blood to its destination—from the right ventricle to the lungs, and from the left ventricle to the aorta for dis- tribution to the body. From here, the impulse travels on to the right and left ventricles by way of a system of specialized nerve fibers that carry the electrical signals throughout the ventricles. The impulse travels to the first of these fiber bundles called the bundle of His (pronounced like hiss ). The impulse moves along the bundle of His as it divides into the right and left pathways called bundle branches. At the base of the heart the right and left bundle branches
further divide into microscopic muscle branches called the Purkinje fibers. When the impulses reach these fibers, they trigger the ventricles to contract and push blood out into the lungs and body. As the blood moves from the ventricles into the pul- monary artery and aorta for circulation throughout the body, the atria relax and are filled once again with blood by the veins, and the cycle begins again. This cycle lasts, on the average, six-sevenths of a second. This series of contractions, or heartbeats, is repeated over and over again, increasing in frequency during times of exertion or stress and decreasing in frequency during times of rest.
HEART SOUNDS
The sounds associated with the heartbeat, called heart sounds , are due to vibrations in the tissues and blood caused by closure of the valves. Heart sounds are usually divided into normal and abnormal heart sounds. A healthy heart makes a sound described as a lub-dub,
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SA node
Right bundle
Left bundle
Purkinje fibers
Bundle of His
AV node
SA node
Firing from SA node across atria (contraction of atria) to AV node
Firing from AV node to bundle of His, down right and left bundle branches
Firing of Purkinje fibers showing contraction of ventricles
AV node
Purkinje fibers
Bundle of His
FIGURE 11.3. The cardiac cycle. This SA node fires and follows the impulse to the AV node, the bundle of His, the bundle branches, and finally to the Purkinje fibers. Reprinted with permission from Willis MC. Medical Terminology: A Programmed Learning Approach to the Language of Health Care. Baltimore: Lippincott Williams & Wilkins, 2002.
- Paroxysmal atrial tachycardia , which is a rapid heart rate that starts and stops suddenly and unpre- dictably.
- Premature atrial contraction , which describes an extra heartbeat that originates from the atria before it should.
Sometimes abnormal heart rhythms can lead to cardiac arrest , which occurs when the heart suddenly stops pumping effectively and begins to flutter wildly, failing to pump blood to the vital organs of the body. If the heart’s normal rhythm is not reestablished immediately, death will follow within minutes.
BLOOD PRESSURE
The beats of the heart create a pulsating force that keeps blood moving to all parts of the body through the arter- ies. Blood pressure is the measurement of this force, or the pressure exerted by the circulating volume of blood on the walls of the arteries, the veins, and the chambers of the heart each time the heart pumps. Blood pressure is at its highest when the heart pumps blood, or the con- traction of the left ventricle, and called the systolic pres- sure and is the top number given in a blood pressure measurement. When the heart is at rest, between beats, the pressure falls to its lowest point; this is called dias- tolic pressure and is the bottom number given in a blood pressure measurement. Blood pressure varies constantly according to time of day, level of physical exertion, and with anxiety, stress, emotional changes, or other factors. Nearly every encounter with a medical provider includes a blood pressure reading that is entered into the medical record. Blood pressure can be measured man- ually with an instrument called a sphygmomanometer , which measures the maximum pressure (systolic) and lowest pressure (diastolic) made by the beating of the heart. An inflatable cuff is wrapped around a patient’s upper arm and kept in place with Velcro. A tube leads
out of the cuff to a rubber bulb. Another tube leads from the cuff to a gauge with an indicator on it that points at a number corresponding to the blood pressure reading. Air is then forced into the cuff, increasing the pressure and tightening the cuff around the patient’s upper arm. The person taking the blood pressures places the stetho- scope to the patient’s arm and listens to the pulse while the air is slowly released from the cuff. Blood pressure is measured in terms of millimeters of mercury (mmHg). Two numbers are involved in making a blood pressure reading, expressed as a frac- tion, for example, 120/80. The systolic blood pressure, or the top number, represents the maximum pressure in the arteries as the heart contracts and pumps blood into the arteries. It is measured when the pulse is first heard through the stethoscope. The diastolic pressure, which is the bottom number, reflects the minimum blood pressure as the heart relaxes following a contrac- tion and is measured from the moment the sound of the pulse is no longer audible. Blood pressure can also be measured at home using an electronic automatic blood pressure gauge with a digital readout.
COMMON CARDIAC
DISEASES AND
TREATMENTS
Heart disease affects the heart and the blood vessels that supply the heart muscle. Some disorders of the blood vessels can also affect the heart directly. Common terms that may be heard when transcribing symptoms of car- diac problems include cyanosis , a bluish discoloration of the skin and mucous membranes resulting from a lack of oxygen in the blood, or pallor , which means paleness or a decrease or absence of color in the skin. Edema refers to an accumulation of abnormal amounts of fluid in the intercellular tissues, pericardial sac, and other tissues of the body. Diaphoresis refers to profuse
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Indicate whether the following sentences are true (T) or false (F).
- The tricuspid valve is located in the right atrium. T F
- Three layers of tissue form the heart wall. T F
- Abnormal heart sounds are called systoles. T F
- Veins carry oxygen-rich blood away from the heart. T F
- The cardiac cycle is the sequence of events in one heartbeat. T F
SKILLS QUICK CHECK 11.1 (^) ✓
sweating associated with elevated body temperature, physical exertion, or stress. Finally, angina , also called angina pectoris , is severe chest pain that lasts for several minutes and results from an inadequate supply of oxy- gen and blood flow to the heart muscle.
Hypertension
Hypertension , or high blood pressure, describes a con- dition in which the pressure of the blood in the arteries is too high, raising the possibility of damage to the heart and to the walls of the blood vessels. This can occur when the heart pumps blood too forcefully around the body, or when arteries narrow, inhibiting blood flow. There are two types of hypertension: primary hyperten- sion , in which there is no identifiable cause; and sec- ondary hypertension , where another disease or med- ication is the cause. Hypertension causes a number of health complications, including heart disease and strokes. In most cases, the cause of hypertension is unknown, but some researchers believe that a family history of hypertension, smoking, and a diet high in salt and fat resulting in obesity are contributing factors. Stress and excessive alcohol consumption are also thought to play a role. Because of the role hypertension plays in stroke and heart attacks, the first line of treatment is to attempt to bring blood pressure under control with diet and lifestyle modification. Drug therapy is the next step. Depending on the circumstances, various classes of drugs are available to treat hypertension:
- Diuretics.^ Diuretics^ decrease^ blood^ pressure^ by eliminating extra sodium and fluid from the body. The blood vessels do not have to hold so much fluid to circulate, and, thus, blood pressure is reduced. Diuretic medications may include triamterene/ hydrochlorothiazide (Dyazide), furosemide (Lasix), or spironolactone (Aldactone).
- Beta-blockers.^ Beta-blockers^ decrease^ heart^ rate and the amount of blood the heart pumps out with each beat, and relax the blood vessels, which reduces blood pressure. Examples of these drugs include atenolol (Tenormin), metoprolol (Lopressor), or propranolol (Inderal).
- Angiotensin-converting enzyme (ACE) inhibitors. These drugs are used to inhibit the formation of a naturally occurring substance, angiotensin II, which is a very potent chemical that causes the muscles surrounding blood vessels to contract and thereby narrows the blood vessels. The narrowing of the ves- sels increases the pressure within them, causing blood pressure to rise. Angiotensin II is formed from angiotensin I in the blood by the angiotensin converting enzyme. ACE inhibitors prevent produc-
tion of angiotensin II and as a result, blood vessels dilate and blood pressure drops. These drugs may include lisinopril (Prinivil), benazepril (Lotensin), enalapril (Vasotec), quinapril (Accupril) or ramipril (Altace).
- Calcium-channel blockers. Calcium channel block- ers inhibit the movement of calcium into the mus- cle cells of the heart and arteries. Calcium is needed for these muscles to contract. Calcium channel blockers work to decrease the force of the heart’s pumping action (cardiac contraction) and relaxing the muscle cells in the walls of the arteries, which helps them to open and reduce blood pressure. Commonly prescribed calcium-channel blockers include verapamil (Calan), diltiazem (Cardizem), and nifedipine (Procardia XL).
- Angiotensin^ II^ receptor^ blockers^ (ARBs). Like ACE inhibitors, ARBs block the action of the enzyme that causes blood vessels to narrow. As a result, blood vessels may relax and open up. This makes it easier for blood to flow through the ves- sels, which reduces blood pressure. Additionally, these drugs increase the release of sodium and water into the urine, which also lowers blood pres- sure. ARBs reduce blood pressure as effectively as ACE inhibitors but without some of the side effects (such as a cough) associated with ACE inhibitors. Medications commonly prescribed in this category include losartan (Cozaar), olmesartan (Benicar), telmisartan (Micardis), and valsartan (Diovan).
Coronary Artery Disease Coronary artery disease (CAD) refers to the narrowing of the coronary arteries to the extent that the heart mus- cle no longer receives an adequate supply of blood.
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Transcription
Tip:
The cardiac medication digoxin (Lanoxin) is dispensed in 125- mcg (0.125-mg) or 250-mcg (0.25-mg) tablets for oral administration. Do not confuse the dosing of mg (milligrams) and mcg (micrograms). A milligram is larger than a microgram. Therefore, if the physician dictates a zero before the dosage number, the mea- surement is always mg , not mcg ; conversely, if the larger number is dictated, you would use the mea- surement of mcg , not mg.
artery wall, other devices are used. Plaque can be cut out, ablated with a laser, or bored out using a surgical drill bit (a procedure called atherectomy ). Coronary artery bypass graft surgery (CABG, pro- nounced like cabbage ), is a more extensive surgical pro- cedure which restores circulation when occluded, or blocked, coronary arteries prevent normal blood flow to the heart muscle. In this procedure, occluded arteries are replaced with segments (called grafts ) from vessels in other parts of the body which are used to bypass the blocked coronary artery and improving blood flow. Conventional CABG surgery is done by opening the patient’s chest with an incision over the sternum (breast bone) and dividing it to expose the heart. Bypasses may be performed using different blood vessels: Vessels in the chest wall called the left internal mammary artery (LIMA) or right internal mammary artery (RIMA) may be used as grafts; but more often, the greater saphenous vein , which is a large vein located in the leg and thigh, is removed (surgeons refer to this as harvesting the vein) to be used for the bypass procedure. This harvested vein is referred to as a saphenous vein graft (SVG). During the operation, the patient is connected to a heart-lung machine , which is used to provide circula- tion and oxygenate the blood while the heart is stopped by the surgical team in order to perform the bypass. Depending on the number and location of the
blockages, the surgeon might perform between one and seven bypasses. When complete, the new healthy artery or vein graft then carries the oxygenated blood around the blockage in the coronary artery. When the bypass procedure is completed and the graft is in place, the heart is restarted. Once the heart beats normally, the patient is removed from the heart-lung machine, the sternum is closed with stainless steel wire sutures, and the chest and leg wounds are closed with sutures or clips.
Cardiomyopathy Cardiomyopathy is a general term for the progressive impairment of the structure and function of the myocardium, or muscle tissue of the heart. The term derives from the components cardi/o (heart), my/o (mus- cle), and - pathy (disease). Damage prevents the heart from functioning normally, or the walls of the tissue thicken or harden, causing the heart to resist filling to capacity. Cardiomyopathy progresses in most cases, and it is one of the main diseases requiring heart trans- plantation. Dilated cardiomyopathy refers to overall enlarge- ment ( dilation ) of the heart chambers, especially the ventricles. Although this enlargement is a key part of dilated cardiomyopathy, it is not the initial problem but rather the heart’s own response to a weakness of heart muscle and poor pumping ability, resulting in heart fail- ure. Hypertrophic cardiomyopathy is an overgrowth of heart muscle that can impair blood flow both into and out of the heart. The walls of the ventricles thicken (a condition called hypertrophy ) and become stiff, even though the workload of the heart is not increased. Restrictive cardiomyopathy is a disorder in which the
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Transcription
Tip:
The classification of cardiac failure widely used by physicians was developed by the New York Heart Association. This system ascribes the severity of a patient’s cardiac failure using Roman numerals I through IV, with I being asymptomatic and IV denoting severe cardiac failure, symptomatic at rest. Transcribe this value using lowercase class , followed by a roman numeral (I through IV). Examples: New York Heart Association class II. NYHA class I. IMPRESSION: Cardiac failure, class III.
FIGURE 11.5. Vascular stent used in coronary angioplasty. When the stent expands, each rectangle stretches to a diamond shape. The expanded stent supports the artery and helps prevent restenosis. Reprinted with permission from Nursing Procedures, 4th ed. Ambler: Lippincott Williams & Wilkins, 2004.
ventricles become stiff, but not necessarily thickened, and do not fill normally with blood between heartbeats. Cardiomyopathy may be caused by chronic cardiac dis- ease, excessive alcohol intake, infection due to viruses, or vitamin deficiency disorders. The most common cause, however, is scarring and dilation of the heart mus- cle as a result of a previous heart attack or other forms of atherosclerosis. Usually cardiomyopathy cannot be completely reversed or cured. However, depending on the type of cardiomyopathy, certain drugs may be prescribed, at least initially, to decrease the heart’s workload, regulate the heartbeat, and help prevent blood clot formation and fluid accumulation in the body. These drugs include ACE inhibitors, anticoagulants (commonly called blood thinners ), and diuretics to remove excess fluid from the body.
Valvular Heart Disease
Heart valves regulate the flow of blood through the heart’s four chambers. If these valves malfunction, the heart’s ability to pump blood can be impeded. If heart valves do not close completely, blood can leak back through the valve when it should be closed. This leakage of blood back through the valve is called regurgitation. Valves may not open completely, resulting in blood pumping through a blocked or narrowed opening, called stenosis, as discussed above. Regurgitation and stenosis can affect any of the heart valves and are named according to the site of the defect, such as mitral valve regurgitation, tricuspid regurgitation, and aortic regurgi- tation; or mitral valve stenosis, aortic stenosis, and tri- cuspid stenosis. Mitral valve prolapse is a disorder in which the heart’s mitral valve, which separates the left atrium and left ventricle, bulges slightly back into the left atrium when it closes, causing regurgitation of blood back through the valve and into the atrium. Physicians diag- nose mitral valve prolapse after hearing the characteris- tic clicking sound of the disorder through a stethoscope; hence this disorder is also referred to as click-murmur syndrome. Although prolapse may involve any valve or combination of valves, the mitral valve is the most com- mon site of prolapse. In most cases, mitral valve prolapse is harmless, does not cause symptoms, and does not need to be treated. In a small number of cases where it causes severe mitral regurgitation, it would need to be treated with surgery. Patients with mitral valve prolapse may be prescribed antibiotics before surgical, dental, or medical proce- dures to prevent the risk of bacterial endocarditis. Bacterial endocarditis is an invasion of bacteria from the bloodstream which can lead to deformity and destruc- tion of the valve leaflets.
Pericarditis
Pericarditis is an inflammation of the pericardium that surrounds the heart. There is a small amount of fluid between the inner and outer layers of the pericardium. When the pericardium becomes inflamed, the amount of fluid between its two layers increases, compressing the heart and interfering with its ability to function properly. Pericarditis may be acute or chronic. The sharp chest pain associated with acute pericarditis occurs when the pericardium rubs against the heart’s outer layer. In some cases, the inflammation causes fluid to accumu- late in the pericardial sac, a condition known as peri- cardial effusion. This collection of excess fluid in the pericardium can place pressure on the heart, squeezing it and interfering with its ability to fill adequately and pump blood efficiently. This disorder, known as cardiac tamponade , results in less blood leaving the heart, causing a dramatic drop in blood pressure and literally smothering the life out of it. If left untreated, even for a few minutes, cardiac tamponade can be fatal. Pericarditis may be caused by a bacterial or fungal infection, invasion by cancer cells, or by certain dis- eases such as AIDS, cancer, or tuberculosis. It may also be precipitated by a heart attack or serious chest injury. Pericarditis also can develop shortly after a major heart attack due to the irritation of the underlying damaged heart muscle. In addition, a delayed form of pericarditis may occur weeks after a heart attack or heart surgery because of antibody formation. This delayed pericarditis is known as Dressler syndrome. Many experts believe Dressler’s is due to an autoim- mune response, a mistaken inflammatory response by the body to its own tissues—in this case, the heart and pericardium. Treating pericarditis often involves consideration of the underlying cause as well as the severity of the peri- cardial inflammation. Mild cases of pericarditis may get better on their own without treatment. People with more severe cases may need to be hospitalized for treatment, which typically includes anti-inflammatory medications or corticosteroids to reduce inflamma- tion, and analgesics or narcotics to ease pain. Fluid may be drained from the pericardium using a tech- nique called pericardiocentesis , also referred to as a pericardial window. In this procedure, a surgeon uses a sterile needle or a catheter to remove and drain the excess fluid from the pericardial cavity. In cases of long-term inflammation and chronic recurrences that permanently thicken and scar the pericardium, a surgi- cal procedure called a pericardiectomy is performed, in which the portion of the pericardium that has become rigid, compromising the functioning of the heart, is removed.
11 • Cardiology 281
used depends on a number of factors, especially the severity of the symptoms and the type of disease those symptoms represent. A physician may perform some tests to rule out other etiologies for a patient’s symp- toms, or others to check the severity of symptoms before making a diagnosis.
Blood Tests
Blood tests that measure different components in the blood to determine the overall health of the blood and the heart include the following:
- C-reactive protein test (CRP).^ C-reactive protein^ is a substance found in the blood when inflamma- tion occurs, such as fatty buildup in artery walls. CRP levels help predict cardiac risk. - Homocysteine. Homocysteine is an amino acid that is normally found in small amounts in the blood. Higher levels of homocysteine are associ- ated with increased risk of heart attack and other vascular diseases. The levels may be high due to a deficiency of folic acid or vitamin B12, resulting from heredity, older age, kidney disease, or certain medications. - Lipoprotein (a)^ or Lp(a). Lipoprotein (a), dictated as L P little A , is a biochemical in the body; high concentrations of Lp(a) are associated with prema- ture coronary disease. - Cholesterol particle test. The cholesterol particle test measures the size of the low-density lipoprotein (LDL) cholesterol, called bad cholesterol , particles in the blood. “Pattern A” particles are larger and lighter, whereas “Pattern B” particles are smaller
11 • Cardiology 283
Circle the letter corresponding to the best answer to the following questions.
- Coronary artery disease is also known as A. CABG. B. cardiac angiography. C. cardiac ischemia. D. hypertension.
- A buildup of plaque in the coronary arteries is known as A. atherosclerosis. B. arteriomyosis. C. angina pectoris. D. MI.
- Blood pressure is measured with an instrument called a(an) A. syringometer. B. stethoscope. C. EKG monitor. D. sphygmomanometer.
- A heart defect or problem present at birth is known as a A. ventriculomegaly. B. atrial heart defect. C. myocardial heart defect. D. congenital heart defect.
- Progressive impairment and function of the myocardium is known as A. cardiomyopathy. B. ventricular septal defect. C. patent ductus ateriosis. D. pericarditis.
SKILLS QUICK CHECK 11.2 (^) ✓
and more dense. People with Pattern B LDL cho- lesterol are more likely to have atherosclerosis and heart disease. This test is dictated as “ Pattern A” (or “Pattern B”) particle size, where the word pattern and the A or B are enclosed in quotation marks.
- Lipid profile. This test evaluates the risk of coronary heart disease in a patient. It measures total choles- terol; LDL; high-density lipoprotein (HDL), called good cholesterol; and triglycerides.
- Blood sugar (glucose). This test detects the pres- ence of diabetes and glucose intolerance, both of which indicate a significant cardiac risk.
- B-type natriuretic peptide^ (BNP). This test mea- sures the amount of the BNP hormone in the blood. BNP is made by the heart, and if the heart is working harder over an extended period (such as from heart failure), the heart releases more BNP and the value will be elevated.
- Cardiac^ enzyme^ studies.^ These^ blood^ values measure the levels of the cardiac enzymes tro- ponin , creatine kinase (CK), myocardial band enzymes of creatine kinase (CK-MB), creatine phosphokinase (CPK), and myocardial band enzymes of creatine phosphokinase (CPK-MB) in the blood. Elevated levels of cardiac enzymes indicate heart muscle damage. These enzymes, normally found in high numbers inside the cells of the heart, are needed for those cells to func- tion. When these cells are injured, such as during a heart attack or other cardiac trauma, these enzymes are released into the bloodstream. By measuring the levels of these enzymes, physi- cians can determine if cardiac tissue has been damaged, the size of an adverse heart event (such as a heart attack), and approximately when the event occurred.
Electrocardiogram
An electrocardiogram (EKG, also called ECG) is a diag- nostic test that analyzes the electrical activity of the heart. Recorded from electrodes attached to the surface of the body, the EKG produces a graphic representation or tracing of the electrical activity of the heart as it con- tracts and relaxes. The EKG can detect abnormal heart- beats, some areas of damage, inadequate blood flow, and heart enlargement. During the test, electrodes used to measure electrical impulses, called leads , are placed on the patient’s arms and legs and across the chest wall. The leads are then connected to the EKG machine. These leads, 12 in all, are transcribed as a combination of letters and numbers according to their location on the body as leads I, II, and
III, aVR, aVL, and aVF, and, finally, leads V1 through V6. Each electrical impulse detected by the leads is recorded onto a strip of paper as a waveform. Any deviation from the shape of the waveform, or the interval between waveforms on the strip is indicative of a possible heart disorder. Figure 11.6 illustrates a waveform tracing showing normal sinus rhythm compared to the wave- form appearance of abnormal rhythms. Below are same common terms used to transcribe EKG terminology. EKG leads (including augmented limb and precor- dial leads):
- lead I, lead II, lead III
- aVR, aVL, aVF
- V1, V2, V3, V4, V5, V6, V7, V8, V or V 1 , V 2 , V 3 , V 4 , V 5 , V 6 , V 7 , V 8 , V (^9) or sometimes dictated as sequential leads: V1 through V9 (V 1 through V 9 ) not V1 through 5 or V 1 through 5 (even if dictated) not V1-5 or V1- Tracing terms (in general, use all capital letters but larger and smaller letters may be used when denoting electro- cardiographic deflections):
- Q wave, q wave
- R wave, r wave
- S wave, s wave
- T wave
- T-wave inversion
- QRS complex
- QT interval
- ST segment
- ST-T elevation
Echocardiogram An echocardiogram , often dictated as echo for short, is a test in which ultrasound is used to examine the anatomy of the heart. This procedure can display a cross-sectional “slice” of the beating heart, including the chambers, valves, and the major blood vessels that exit from the left
284 PART II. MEDICAL SPECIALTIES
Transcription
Tip:
For terms such as T wave , in which there is no hyphen, insert a hyphen when the term is used as an adjective, such as T-wave abnormality.
from a slow walk on the treadmill to a faster pace and walking on an incline; certain changes in the rate and rhythm may suggest the heart itself is not receiving enough blood. A nuclear scan , or thallium stress test , is sometimes used along with a treadmill or bicycle stress test. The scan can show areas of the heart that lack blood flow and are damaged, as well as revealing problems with the heart’s pumping action. When the patient reaches his or her maximum level of exercise, a small amount of radioactive material called thallium is injected into a vein where it travels through the bloodstream. Then the patient lies down on a special table under a gamma camera, a special camera that can see the thallium and take pictures as the thallium mixes with the blood in the bloodstream and heart’s arteries and enters heart muscle cells. A less-than-normal amount of thallium detected in the heart muscle cells is an indicator that this part of the heart muscle does not receive a normal blood sup- ply and might be damaged.
Cardiac Catheterization and
Coronary Angiography
Cardiac catheterization , along with a simultaneous pro- cedure, coronary angiography , allows the visualization of the heart and the coronary arteries that supply blood to the heart muscle. This procedure can evaluate block- ages in coronary arteries, the function of the valves and other heart structures, and coronary circulation and structural disorders. A thin catheter is inserted into an artery or vein and threaded through major blood vessels into the heart chambers. At the tip of the catheter, vari- ous instruments may be attached that measure the pres- sure of blood in each chamber, view the interior of blood vessels, or remove a tissue sample from inside the heart
for examination later. During the coronary angiography portion of the examination, a radiopaque dye is inserted through the catheter into the coronary arteries to view clear images of the blood vessels as the heart pumps.
Multiple Gated Acquisition Scan A multiple gated acquisition (MUGA) scan is a nonin- vasive test that uses a radioactive isotope called tech- netium to evaluate the functioning of the heart’s ventri- cles. The MUGA scan is performed to determine if the heart’s left and right ventricles are functioning properly and to diagnose abnormalities in the heart wall. During the MUGA scan, leads are placed on the patient’s body so that an EKG can be conducted simultaneously. Then a small amount of technetium is injected into an arm vein, and a special camera is used to follow the move- ment of the technetium through the blood circulating in the heart. The camera displays multiple images of the heart in motion and records them on a computer for later analysis.
CHAPTER SUMMARY
The heart, which pumps blood through the circulatory system, is vital to survival. Body tissues need a continu- ous supply of oxygen and nutrients, and metabolic waste products have to be removed. Without these essential processes, cells soon undergo irreversible changes that lead to death. A critical understanding of the anatomy and function of the heart and familiarity with the ongoing diagnostic and therapeutic advances in managing heart disease are key factors in success at transcribing medical reports in the field of cardiology.
286 PART II. MEDICAL SPECIALTIES
Fill in the blank with the correct meaning of the following abbreviations.
- EKG
- CABG
- CK
- HDL
- BNP
SKILLS QUICK CHECK 11.3 (^) ✓
11 • Cardiology 287
- I • N • S • I • G • H • T •
The Heart Brain
Western science has long believed that the brain’s responses to external stimuli were the sole source of human emotion, whereas the hollow muscle of the heart possessed no emotion or intellect of its own. However, neuro- physiologists have discovered that the heart is, in fact, is a sensory organ with its own functional intrinsic “brain” that communicates with and influences the brain via the nervous system and other pathways.
Dr. J. Andrew Armour, Associate Professor of Pharmacology, University of Montreal, pioneered the concept that the “heart brain” is a network of neurons, neurotransmitters and proteins that send messages to the body. Through his research, he found that, like the brain, the heart contains support cells and a complex electrical cir- cuitry that enable it to act independently, learn, remember, and transmit information from one cell to another. According to these studies, the type of information sent from the heart to the brain can influencing human per- ceptions, emotions, and thought processes. Some evidence to support this theory includes the documented tes- taments of heart-transplant patients who have taken on the habits, tastes, and memories of their dead donors. This led many researchers to conclude that the same type of memory-encoding neurons found in the brain are also found in the heart.
With new discoveries supporting the existence of a connection between the heart and the brain, neurocardiol- ogy is becoming increasingly relevant in the management of heart disease. Researchers hope that an under- standing of how the neurons of the heart can exert dynamic control over emotions will help patients to focus on the power of the heart to facilitate beneficial changes in all parts of the body.
11 • Cardiology 289
Combining Forms
Combining Form Meaning
ablat/o take away anastom/o establish an opening angi/o, vas/o, vascul/o vessel aort/o aorta arter/o, arteri/o artery ather/o fatty plaque atri/o atrium cardi/o, coron/o heart cholesterol/o cholesterol congest/o accumulation of fluid cyan/o blue ectop/o outside of a place fibrillo/o muscle fiber/nerve fiber infarct/o area of dead tissue isch/o keep back, block jugul/o jugular (throat) lipid/o lipid (fat) lumin/o lumen (opening) my/o muscle ox/o oxygen palpit/o to throb percardi/o pericardium perone/o fibular (lower leg bone) phleb/o, ven/o vein regurgitat/o flow backward rhythm/o rhythm sphygm/o pulse sten/o narrowness; constriction steth/o chest thromb/o clot valv/o, valvul/o valve ventricul/o ventricle
Add Your Own Combining Forms Here:
Abbreviation Meaning ACE angiotensin-converting enzyme ARB angiotensin II receptor blocker ASD atrial septal defect BNP B-type natriuretic peptide CABG coronary bypass artery graft CAD coronary artery disease CHF congestive heart failure CK creatine kinase CPK creatine phosphokinase CRP C-reactive protein EKG (also electrocardiogram called ECG) HDL high-density lipoprotein, or good cholesterol LAD left anterior descending artery LCA left coronary artery LCA left circumflex artery LDL low-density lipoprotein, or bad cholesterol LP(a) lipoprotein (a) METS metabolic equivalents MI myocardial infarction mmHg the measurement of blood pressure values MUGA multiple gated acquisition scan PDA posterior descending artery OR patent ductus arteriosus PND paroxysmal nocturnal dyspnea PTCA percutaneous transluminal coro- nary angioplasty RCA right coronary artery SA sinoatrial (node) TIMI thrombolysis in myocardial infarction VSD ventricular septal defect
Add Your Own Abbreviations Here:
ABBREVIATIONSABBREVIATIONS
290 PART II. MEDICAL SPECIALTIES
Term Meaning angina Severe chest pain that lasts for several minutes and results from an inadequate supply of oxygen and blood flow to the heart muscle. angina pectoris Another term for angina. angioplasty A procedure that opens narrowed arteries by using a catheter with a balloon on its tip; also referred to as percutaneous transluminal coronary angioplasty (PTCA). angiotensin-converting Drugs that prevent the formation of angiotensin II in the blood vessels, enzyme (ACE) inhibitors enabling blood vessels to dilate and decrease blood pressure. anticoagulant A substance that hinders the clotting of blood; commonly called blood thinner. aorta The main trunk of the arterial system that begins in the left ventricle. aortic valve The outgoing valve of the left ventricle. angiotensin II receptor Drugs that block the action of the enzyme that causes blood vessels to blockers (ARBs) narrow; similar to ACE inhibitors but without some of the side effects associ- ated with ACE inhibitors. arrhythmia An irregular heartbeat. arteries Larger vessels that carry oxygen-rich blood away from the heart. arterioles Smaller branches of the arteries that distribute blood to body tissues. atherectomy A procedure in which a high-speed drill on the tip of a catheter is used to shave plaque from blocked arterial walls. atherosclerosis A buildup of plaques in the coronary arteries, causing the arteries to become hardened and narrowed. atria (singular, atrium) An upper chamber of the heart. atrial fibrillation An uncoordinated, irregular contraction of the heart muscle which may orig- inate in the atria. atrial flutter An arrhythmia in which the atrial rhythm is regular, but the rate is abnormally fast. atrial septal defect (ASD) A hole in the atrium septum that separates the atria of the heart. atrioventricular (AV) node The electrical connection between the atria and ventricles where electrical impulses are delayed for a fraction of a second to allow the ventricles to fill completely with blood. bacterial endocarditis An infection leading to deformity and/or destruction of the inner layer of the heart. beta-blockers Drugs that slow the heart rate and reduce the force of the heartbeat. blood pressure The force of blood exerted on the inside walls of blood vessels. blood vessels A network of interconnecting arterial, arterioles, capillaries, venules, and veins which provide the pathway in which blood is transported between the heart and body cells. bradycardia A slow heartbeat, usually less than 60 beats per minute. Bruce protocol The standardized treadmill stress test used for diagnosing and evaluating heart and lung diseases.
TERMINOLOGYTERMINOLOGY
