Chapter 19: Disorders of cardiac function Porth

The ___ is the most frequently used cardiovascular diagnostic procedure.

12-Lead ECG

Pericardial effusion

Accumulation of fluid in the pericardial cavity

ST-elevated myocardial infarction is accompanied by severe, crushing pain. Morphine is the drug of choice used to treat the pain of STEMI when the pain cannot be relieved with oxygen and nitrates. Why is morphine considered the drug of choice in STEMI?

Action decreases metabolic demands of the heart. Although a number of analgesic agents have been used to treat the pain of STEMI, morphine is usually the drug of choice. It usually is indicated if chest pain is unrelieved with oxygen and nitrates. The reduction in anxiety that accompanies the administration of morphine contributes to a decrease in restlessness and autonomic nervous system activity, with a subsequent decrease in the metabolic demands of the heart. Morphine does not cause a feeling of depression to the client.

___ myocardial infarction is characterized by the ischemic death of myocardial tissue associated with atherosclerotic disease of the coronary arteries.

Acute ST-segment

It is known that over 100 distinct myocardial diseases can demonstrate clinical features associated with dilated cardiomyopathy (DCM). What is the most common identifiable cause of DCM in the United States?

Alcoholic cardiomyopathy is the single most common identifiable cause of dilated cardiomyopathy (DCM) in the United States and Europe.

Myocarditis

An inflammation of the heart

___ is a mechanical technique to remove atherosclerotic tissue during angioplasty.

Atherectomy

___ is by far the most common cause of coronary artery disease (CAD).

Atherosclerosis

Mitral valve prolapse occurs frequently in the population at large. Its treatment is aimed at relieving the symptoms and preventing complications of the disorder. Which drug is used in the treatment of mitral valve prolapse to relieve symptoms and aid in preventing complications?

Beta-adrenergic-blocking drugs. Persons with palpitations and mild tachyarrhythmias or increased adrenergic symptoms and those with chest discomfort, anxiety, and fatigue often respond to therapy with Beta-adrenergic-blocking drugs.

Describe the clinical manifestation of patent ductus arteriosus.

Blood typically shunts across the ductus from the higher pressure left side to the lower pressure right side. A murmur is typically detected within days or weeks of birth. The murmur is loudest at the second left intercostal space, continuous through systole and diastole, and has a characteristic machinery sound. A widened pulse pressure is common because of the continuous runoff of aortic blood into the pulmonary artery.

Prinzmetal angina

Chest pain due to a coronary artery spasm

Unstable angina

Chest pain occurring while at rest

Effusive-constrictive pericarditis

Combination of effusion-tamponade and construction

Ion channelopathies

Conduction disorders in the heart resulting from abnormal membrane potentials (long QT/short QT syndromes)

When an acute MI occurs, many physiologic changes occur very rapidly. What causes the loss of contractile function of the heart within seconds of the onset of an MI?

Conversion from aerobic to anaerobic metabolism. The principal biochemical consequence of MI is the conversion form from aerobic to anaerobic metabolism with inadequate production of energy to sustain normal myocardial infarction. As a result, a striking loss of contractile function occurs within 60 seconds of onset.

Ischemia

Decreased blood flow to tissue

Pulsus paradoxus

Exaggeration of the normal variation in the pulse during the inspiratory phase of respiration

Left ventricular noncompaction

Failure of trabecular compaction in the developing myocardium

Cardiomyopathies are classified as either primary or secondary. The primary cardiomyopathies are further classified as genetic, mixed, or acquired. Identify whether the following conditions are classified as genetic, acquired, or mixed. A. Hypertrophic cardiomyopathy; B. Left ventricular noncompaction; C. myocarditis; D. Dilated cardiomyopathy; E. Peripartum cardiomyopathy.

Hypertrophic cardiomyopathy - genetic Left ventricular noncompaction - genetic Myocarditis - acquired Dilated cardiomyopathy - mixed Peripartum cardiomyopathy - acquired

Infective endocarditis

Invasion of the heart valves and the mural endocardium by a microbial agent.

____ disease, also known as mucocutaneous lymph node syndrome, is an acute febrile disease of young children.

Kawasaki

Stress cardiomyopathy

Left ventricular dysfunction in response to profound psychological or emotional stress

Cardiac tamponade

Mechanical compression of the heart

Antibodies directed against the M protein of certain strains of streptococcal bacteria seem to cross-react with glycoprotein antigens in the heart, joint, and other tissues to produce an autoimmune response resulting in rheumatic fever and rheumatic heart disease. This occurs through what phenomenon?

Molecular mimicry. It is thought that antibodies directed against the M protein of certain strains of streptococci cross-react with glycoprotein antigens in the heart, joint, and other tissue to produce an autoimmune response through a phenomenon called molecular mimicry.

Peripartum cardiomyopathy

Occurs during the last trimester of pregnancy or the first 6 months after delivery

Silent myocardial ischemia

Occurs in the absence of anginal pain

___ is the most common, and frequently the first, manifestation of rheumatic fever.

Polyarthritis

Cardiac tamponade is a serious life-threatening condition that can arise from a number of other conditions. What is a key diagnostic finding in cardiac tamponade?

Pulsus paradoxus. A key diagnostic finding is pulsus paradoxus or an exaggeration of the normal variation in the systemic arterial pulse volume with respiration.

Heart attack

ST elevation myocardial infarction

Unstable angina (UA)/non-ST-segment elevation myocardial infarction (NSTEMI) is a clinical syndrome that ranges in severity between stable angina to MI. It is classified according to its risk of causing an acute MI and is diagnosed based on what?

Serum biomarkers and ECG pattern. UA/NSTEMI is classified as either low or intermediate risk of acute MI, the diagnosis of which is based on the clinical history, ECG pattern, and serum biomarkers.

Describe the pathologic process that is seen in unstable angina/non-ST-segment elevation myocardial infarction.

The pathophysiology is divided into three phases: development of the unstable plaque that ruptures, the acute ischemic event, and the long-term risk of recurrent events that remain after the acute event. Inflammation plays a prominent role in plaque instability, with inflammatory cells releasing cytokines that cause the fibrous cap to become thinner and more vulnerable to rupture. The acute ischemic event can be caused by an increase in myocardial oxygen demand precipitated by tachycardia or hypertension or, more commonly, by a decrease in oxygen supply related to a reduction in coronary lumen diameter due to platelet-rich thrombi or vessel spasm.

Dilated cardiomyopathy

Ventricular enlargement, a reduction in ventricular wall thickness, and impaired systolic function

Restrictive cardiomyopathy

Ventricular filling is restricted because of excessive rigidity of the ventricular walls

Hypertrophic cardiomyopathy

With disproportionate thickening of the ventricular septum and left ventricle

Congenital heart defects that result in a left-to-right shunt are usually characterized as ____ disorders because they do not compromise oxygenation of blood in the pulmonary circulation.

acyanotic

In most cases, coronary artery disease (CAD) is caused by ____.

atherosclerosis

Coronary artery disease is commonly divided into two types of disorders: ___ and ___.

chronic ischemic heart disease, acute coronary syndrome

In ___ pericarditis, fibrous, calcified scar tissue develops between the visceral and parietal layers of the serous pericardium.

constrictive

There is little oxygen reserve in the blood; therefore, coronary arteries must increase their flow to meet the metabolic needs of the myocardium during periods of ___.

increased activity

Myocardial blood flow, in turn, is largely regulated by the ____ of the myocardium and ___ mechanisms that control vessel dilation.

metabolic activity, autoregulatory

Mitral valve ____ is characterized by incomplete closures of the mitral valve, with the left ventricular stroke volume being divided between the forward stroke volume that moves into the aorta and the regurgitant stroke volume that moves back into the left atrium during systole.

regurgitation

Acute severe ischemia reduces the ____ and shortens the duration of the action potential in the ischemic area.

resting membrane potential

Increased resistance to ejection of blood from the left ventricle into the aorta characterizes aortic valve ____.

stenosis

The ____ cardiomyopathies include hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, left ventricular noncompaction cardiomyopathy, inherited conduction system disorders, and ion channelopathies.

genetic

Irreversible myocardial cell death occurs after ____ minutes of severe ischemia.

20 to 40

During an acute MI there is ischemic damage to the heart muscle. The location and extent of the ischemic damage is the major predictor of complications, ranging from cardiac insufficiency to death, following an MI. What is the "window of opportunity" in restoring blood flow to the affected area so as to diminish the ischemic damage to the heart and maintain the viability of the cells?

20 to 40 minutes. If blood flow can be restored within the 20- to 40- minute time frame, loss of cell viability does not occur or is minimal.

Pericardial fluid acts as a lubricant that prevents ___ forces from developing as the heart contracts and relaxes.

frictional

What is the definition of cardiomyopathy, according to the American Heart Association?

A cardiomyopathy is a heterogeneous group of diseases of the myocardium associated with mechanical and/or electrical dysfunction that usually exhibit inappropriate ventricular hypertrophy or dilation and are due to a variety of causes that frequently are genetic. Cardiomyopathies either are confined to the heart or are part of generalized systemic disorders, often leading to cardiovascular death or progressive heart failure-related disability.

Tetralogy of Fallot is a congenital condition of the heart that manifests in four distinct anomalies of the infant heart. It is considered a cyanotic heart defect because of the right-to-left shunting of the blood through the ventricular septal defect. A hallmark of this condition is the "tet spells" that occur in these children. What is a tet spell?

A hypercyanotic attack brought on by periods of stress. The degree of obstruction may be dynamic and can increase during periods of stress causing hypercyanotic attacks ("tet spells").

What changes are seen in the blood (serum) during acute coronary syndrome (ACS)?

Biomarkers for acute coronary syndrome (ACS) include cardiac-specific troponin I (cTnI) and troponin T (cTnT), myoglobin, and creatine kinase MB (CK-MB). As the myocardial cells become necrotic, their intracellular enzymes begin to diffuse into the surrounding interstitium and then into the blood.

____ cardiomyopathies are characterized by atrophic and hypertrophic myocardial fibers and interstitial fibrosis.

Dilated

Heart failure in an infant usually manifests itself as tachypnea or dyspnea, both at rest and on exertion. When does this most commonly occur with an infant?

During feeding. Heart failure manifests itself as tachypnea or dyspnea at rest or on exertion. For the infant, this most commonly occurs during feeding.

___ uses ultrasound signals that are inaudible to the human ear.

Echocardiography

Angina pectoris is a chronic ischemic CAD that is characterized by a symptomatic paroxysmal chest pain or pressure sensation associated with transient myocardial ischemia. What precipitates an attack of angina pectoris?

Emotional stress. Angina pectoris usually is precipitated by situations that increase the work demands of the heart, such as physical exertion, exposure to cold, and emotional stress. The pain typically is describes as a constricting, squeezing, or suffocating sensation. It usually is steady, increasing in intensity only at the onset and end of the attack. Changing positions abruptly does not cause an attack of angina pectoris.

Nearly everyone with pericarditis has chest pain. With acute pericarditis the pain is abrupt in onset, sharp, and radiates to the neck, back, abdomen, or sides. What can be done to ease the pain of acute pericarditis?

Have the patient sit up and lean forward. The pain typically is worse with deep breathing, coughing, swallowing, and positional changes because of changes in venous return and cardiac filling.

Arrhythmogenic right ventricular cardiomyopathy

Hear muscle disease that affects primarily the right ventricle

Secondary cardiomyopathy

Heart muscle disease in the presence of a multisystem disorder

The scar tissue that occurs between the layers of the pericardium becomes rigid and constrictive from scar tissue in constrictive pericarditis. What is a physiologic sign of constrictive pericarditis?

Kussumaul sign is an inspiratory distention of the jugular veins caused by the inability of the right atrium, encased in its rigid pericardium, to accommodate the increase in venous return that occurs with inspiration.

What factors determine myocardial oxygen supply and demand?

Myocardial oxygen supply is determined by the coronary arties, capillary inflow, and the ability of hemoglobin to transport and deliver oxygen to the heart muscle. Important factors in the transport and delivery of oxygen include the fraction of inspired oxygen in the blood and the number of red blood cells with normal functioning hemoglobin. There are three major determinants of myocardial oxygen demand (Mvo2); the heart rate, myocardial contractility, and the myocardial wall stress or tension. The heart rate is the most important factor in the myocardial oxygen demand for two reasons: (1) as the heart rate increases, myocardial oxygen consumption or demand also increases; and (2) subendocardial coronary blood flow is reduced because of the decreased diastolic filling time with increased heart rates.

How does an atherosclerotic plaque stimulate thrombosis?

On rupture, lipid core provides a stimulus for platelet aggregation and thrombus formation. Both smooth muscle and foam cells in the lipid core contribute to the expression of tissue factor in unstable plaques. Once exposed to blood, tissue factor initiates the extrinsic coagulation pathway, resulting in the local generation of thrombin and deposition of fibrin.

The diagnosis of chronic stable angina is based on a detailed pain history, the presence of risk factors, invasive and noninvasive studies, and laboratory studies. What test is not used in the diagnosis of angina?

Serum biochemical markers for MI are normal in patients with chronic stable angina.

What is the relationship between strep throat and heart valve disorders?

Rheumatic heart disease is a complication of immune-mediated response to group A streptococcal throat infection. The acute stage of rheumatic fever includes a history of an initiating streptococcal infection and subsequent involvement of the connective tissue elements of the heart, blood vessels, joints, and subcutaneous tissues. The recurrent phase usually involves extension of the cardiac effects of the disease. The chronic phase of rheumatic fever is characterized by permanent deformity of the heart valves.

Unstable plaque, a condition of atherosclerotic heart disease, occurs in unstable angina and myocardial infarction. Unstable plaque can rupture, causing platelet aggregation and thrombus formation. What are the major determinants of the vulnerability of plaque to rupture?

Size of lipid-rich core, presence of inflammation, and thickness of fibrous cap. The major determinants of plaque vulnerability to disruption include the size of the lipid-rich core, the stability and thickness of its fibrous cap, the presence of inflammation, and lack of smooth muscle cells. A decrease in blood pressure and coronary blood flow are not determinants of plaque vulnerability to rupture.

___ is the initial manifestation of ischemic heart disease in approximately half of the persons with coronary artery disease (CAD).

Stable angina

The classic ECG changes that occurs with acute coronary syndrome (ACS) involve ____, ____, and ____.

T-wave inversion, ST-segment elevation, development of an abnormal Q wave

Describe the tetralogy of Fallot.

Tetralogy of Fallot consist of four associated defects: (1) a ventricular septal defect involving the membranous septum and the anterior portion of the muscular septum (2) dextroposition or shifting to the right of the aorta; (3) obstruction or narrowing of the pulmonary outflow channel, including pulmonic valve stenosis, a decrease in the size of the pulmonary trunk, or both; and (4) hypertrophy of the right ventricle because of the increased work required to pump blood through the obstructed pulmonary channels.

What are the classic symptoms of a STEMI?

The classic symptoms of a STEMI include: Onset of event that is abrupt and having pain as the significant symptom; pain is typically severe and crushing and usually substernal; the pain can radiate to the left arm, neck, or jaw; pain is not relieved by rest or nitroglycerin; gastrointestinal distress, including nausea and vomiting; fatigue and weakness, especially of the arms and legs; tachycardia, anxiety, restlessness, and feelings of impending doom; pale, cool, moist skin.

What is the damage that results from an acute myocardial infarction and what are the factors that determine severity?

The extent of the infarct depends on the location and extent of occlusion, amount of heart tissue supplied by the vessel, duration of the occlusion, metabolic needs of the affected tissue, extent of collateral circulation, and other factors such as heart rate, blood pressure, and cardiac rhythm. An infarct may involve the endocardium, myocardium, epicardium, or a combination of these.

Why does pericardial effusion demonstrate signs of right-sided heart failure?

The pericardial cavity has little reserve volume, so small additions of fluid increase the pericardial pressure. Right heart filling pressures are lower than the let, and increases in pericardial fluid pressure will result in decreased right-side filling.

What is meant by "reperfusion therapy" and what is its goal?

The term reperfusion refers to re-establishment of blood flow through use of fibrinolytic therapy, percutaneous coronary intervention, or coronary artery bypass grafting. Early reperfusion (within 15 to 20 minutes) after onset of ischemia can prevent necrosis and improve myocardial perfusion in the infarct zone. Reperfusion after a longer interval can salvage some of the myocardial cells that would have died owing to longer periods of ischemia. It may also prevent microvascular injury that occurs over a longer period.

In infective endocarditis vegetative lesions grow on the valve of the heart. These vegetative lesions consist of a collection of infectious organisms and cellular debris enmeshed in the fibrin strands of clotted blood. What are the possible systemic effects of these vegetative lesions?

They can fragment and cause cerebral emboli. The intracardiac vegetative lesions also have local and distant systemic effects. The loose organization of these lesions permits the organisms and fragments of the lesion to form emboli and travel in the bloodstream, causing cerebral, systemic, or pulmonary emboli. Preventing the valves of the heart from either opening or closing completely is not a systemic effect of the lesions. Fragmentation of the lesions does not make them larger.

A patient with a suspected MI is brought to the emergency department by ambulance. As the nurse caring for this patient, what laboratory work would you expect to receive an order for, to confirm a diagnosis of MI?

Troponin level. The troponin assays have high specificity for myocardial tissue and have become the primary biomarker for the diagnosis of myocardial infarction (MI). The troponin complex, which is part of the actin filament, consists of three subunits (i.e. TnC, TnT, and TnI) that regulate calcium-mediated actin-myosin contractile process in striated muscle. TnI and TnT, which are present in cardiac muscle, begin to rise within 3 hours after the onset of MI and may remain elevated for 7 to 10 days after the event. This is especially adventitious in the late diagnosis of MI. The other blood work may be ordered, but not to confirm the diagnosis of MI.

Congenital heart defects produce their effects mainly through abnormal shunting of ____, production of ____ and disruption of ____ blood flow.

blood, cyanosis, pulmonary

Pericardial ___ refers to the accumulation of fluid in the pericardial cavity, usually because of an inflammatory and or infectious process.

effusion

Typically, chronic stable angina is provoked by ____ or ___ stress and relieved within minutes by rest or the use of nitroglycerin.

exertion, emotional

The major development of the ____ occurs between the fourth and seventh week of gestation, and most congenital heart defects arise during this time.

fetal heart

The physiologic abnormality in ___ is reduced left ventricular chamber size, poor compliance with reduced stroke volume that results from impaired diastolic filling, and dynamic obstruction of left ventricular outflow.

hypertrophic cardiomyopathy

The ____ cardiomyopathies, which include dilated cardiomyopathy, are of both genetic and nongenetic origin.

mixed

The ____ manifestation of rheumatic fever is Sydenham chorea, in which the child often is fidgety, cries easily, begins to walk clumsily, and drops things.

neurologic

The medication used to alleviate angina, ___ is given because of its vasodilating effect.

nitroglycerin

Partial or complete rupture of a ___ is rare but often fatal complication of transmural myocardial infarction.

papillary muscle

The manifestations of acute ___ include a triad of chest pain, pericardial friction rub, and ECG changes.

pericarditis

The __ is a double-layered serous membrane that isolates the heart from other thoracic structures, maintains its position in the thorax, prevents it from overfilling, and serves as a barrier to infection.

pericardium

Most persons with mitral valve ___ are asymptomatic and the disorder is discovered during a routine physical examination.

prolapse

Aortic ___ is the result of an incompetent aortic valve that allows blood to flow back to the left ventricle during diastole.

regurgitation

There are two types of atherosclerotic lesions: the ____ plaque, which obstructs blood flow, and the ___ plaque, which can rupture and cause platelet adhesion and thrombus formation.

stable, unstable

Mitral valve ____ represents the incomplete opening of the mitral valve during diastole with left atrial distention and impaired filling of the left ventricle.

stenosis

Pericardial effusion can lead to cardiac ____, in which there is compression of the heart due to the accumulation of fluid, pus, or blood in the pericardial sac.

tamponade

The ____ have high specificity for myocardial tissue and have become the primary biomarker for the diagnosis of myocardial infarction (MI).

troponin assays

The gastrointestinal symptoms of STEMI are thought to be related to the severity of the pain and ___ stimulation.

vagal

The function of the heart _____is to promote directional flow of blood through the chambers of the heart.

valves

Infarcted and noninfarcted areas of the heart muscle in patients with ST-segment elevation myocardial infarction (STEMI) can change size, shape, and thickness, a term referred to as _____.

ventricular remodeling

A ____ defect is an opening in the ventricular septum that results from an incomplete separation of the ventricles during early fetal development.

ventricular septal