4TH SEMESTER URDEN Exam Questions completed Correctly

4TH SEMESTER URDEN Exam Questions completed Correctly 4TH SEMESTER URDEN Exam Questions 1. Which of the following structures is the primary pacemaker of the heart? a. Ventricular tissue c. Sinoatrial node b. Atrioventricular node d. Purkinje fibers ANS: C With an intrinsic rate of 60 to 100 beats/min, the sinoatrial node is the primary pacemaker in a healthy heart. The atrioventricular node beats 40 to 60 beats/min. Ventricular tissue must have an electrical impulse to contract. Purkinje fibers beat 15 to 40 beats/min. 2. The atrioventricular (AV) node delays the conduction impulse from the atria (0.8-1.2 seconds) for which of the following reasons? a. To limit the amount of blood that fills the ventricle from the atria b. To provide time for the ventricles to fill during diastole c. To limit the number of signals the ventricles receive in some rhythms d. To allow the atria to rest between signals ANS: B The AV node delays the conduction impulse from the atria (0.8-1.2 seconds) to provide time for the ventricles to fill during diastole. 3. Why do many patients with very high heart rates frequently have chest pain and shortness of breath? a. Patients with heart disease frequently have an anxiety disorder as well. b. The rapid pounding of the heart in the chest wall causes the physical pain. c. The heart muscle gets tired from the increased work. d. The decreased diastolic time decreases oxygen delivery to the myocardium. ANS: D The coronary arteries are perfused during diastole. When the heart rate increases, the diastolic time decreases as each contraction has less time to be completed. This decreases the time the coronary arteries have to deliver oxygenated blood to the myocardium. The symptoms described are caused by a lack of oxygen in the myocardium. 4. A patient reports feeling dizzy after standing quickly. Which of the following could provide a clue regarding the cause? a. Hemoglobin level of 14.0 g/dL and hematocrit level of 42.3% b. Poor skin turgor with extended tenting c. Supine blood pressure of 146/93 mm Hg d. Resting heart rate of 96 beats/min ANS: B Poor skin turgor could suggest dehydration. Dehydration can cause orthostatic hypotension because of low capacitance reserves from hypovolemia. Supine blood pressure of 146/93 mm Hg would be considered hypertensive, and the patient would most likely experience a headache rather than dizziness. A resting heart rate of 96 beats/min is still considered a normal value. 5. A patient presents with atrial fibrillation, a heart rate of 156 beats/min, and a blood pressure of 124/76 mm Hg. The physician orders diltiazem, a calcium channel blocker, to be given slowly by intravenous push. Why did the physician choose this medication to treat this patient's atrial tachyarrhythmia? a. Diltiazem decreases the calcium influx into the AV nodal tissue and decreases the speed of impulse conduction. b. Diltiazem increases the calcium influx into the AV nodal tissue and decreases the speed of impulse conduction. c. Diltiazem decreases the calcium influx into the myocardial tissue and decreases the strength of heart contraction. d. Diltiazem increases the calcium influx into the myocardial tissue and decreases the strength of heart contraction. ANS: A Calcium channel-blocking drugs, such as verapamil and diltiazem, inhibit the inward Ca++ current into pacemaker tissue, especially the AV node. For this reason, they are used therapeutically to slow the rate of atrial tachydysrhythmias and protect the ventricle from excessive atrial impulses. 6. The hemodynamic effects of a pericardial effusion include a. increased ventricular ejection. c. myocardial ischemia. b. decreased ventricular filling. d. increased afterload. ANS: B If the fluid collection in the sac (pericardial effusion) impinges on ventricular filling, ventricular ejection, or coronary artery perfusion, a clinical emergency may exist that necessitates removal of the excess pericardial fluid to restore normal cardiac function. Myocardial ischemia is damage of the myocardium muscle as the result of a heart attack. 7. The contribution of atrial kick to ventricular filling is approximately a. 10%. c. 5%. b. 20%. d. 45%. ANS: B Atrial contraction, also known as "atrial kick," contributes approximately 20% of blood flow to ventricular filling; the other 80% occurs passively during diastole. 8. The function of the AV valves is to a. prevent backflow of blood into the atria during ventricular contraction. b. prevent blood regurgitation back into the ventricles. c. assist with blood flow to the lungs and aorta. d. contribute to ventricular filling by atrial kick. ANS: A The AV valves are open during ventricular diastole (filling) and prevent backflow of blood into the atria during ventricular systole (contraction). Semilunar valves prevent the backflow of pulmonic and aortic blood back into the ventricles. 9. Which step of impulse conduction is most conducive to atrial kick? a. The firing of the sinoatrial node, which results in atrial depolarization b. The conduction delay at the AV node, allowing time for filling c. Conduction through the bundle of His, enhancing ventricular depolarization d. Conduction to the Purkinje fibers, allowing for ventricular contraction ANS: B The conduction delay at the AV node allows adequate time for ventricular filling from atrial contraction. 10. Which of the following is an example of a physiologic shunt? a. A ventricular septal defect b. Blood returning from the inferior vena cava to the right atrium c. A septal infarct d. Thebesian vessels returning deoxygenated blood to the left ventricle ANS: D The thebesian vessels return blood to the left ventricle. The mixing of unoxygenated blood with freshly oxygenated blood is called a physiologic shunt. A ventricular septal defect (VSD) allows mixing of blood from both ventricles. The clinical impact depends on the size of the intracardiac shunt. A VSD is a congenital opening between the ventricles; a ventricular septal rupture can occur as a complication of a large anterior wall myocardial infarction. 11. The outermost layer of the artery that helps strengthen and shape the vessel is the a. tunica. c. adventitia. b. intima. d. media. ANS: C The adventitia is the outermost layer of the artery that helps strengthen and shape the vessel. The media is the middle layer that is made up of smooth muscle and elastic tissue. The intima is the innermost layer consists of a thin lining of endothelium and a small amount of elastic tissue. 12. Which of the following is most descriptive of the capillary? a. Large diameter, low pressure c. Large diameter, high pressure b. Small diameter, high pressure d. Small diameter, low pressure ANS: D The diameter of a capillary is less than that of an arteriole, but the pressure is relatively low as a result of the large cross-sectional area of the branching capillary bed. 13. Depolarization of one myocardial cell will likely result in a. completion of the action potential in that cell before a new cell can accept an impulse. b. quick depolarization and spread to all of the heart. c. depolarization of only cells superior to the initial depolarization. d. depolarization of only cells inferior to the initial depolarization. ANS: B The cardiac muscle is a functional syncytium in which depolarization started in any cardiac cell is quickly spread to all of the heart. 14. In a myocardial cell, the normal resting membrane potential is a. 10 to 20 mV. c. -20 to -30 mV. b. 30 to 40 mV. d. -80 to -90 mV. ANS: D In a myocardial cell, the normal resting membrane potential is -80 to -90 mV. 15. The final repolarization phase of the action potential is a. phase 1. c. phase 3. b. phase 2. d. phase 4. ANS: C The final repolarization phase is phase 3 of the action potential. Phases 1 and 2 (partial repolarization) occur as the AP slope returns toward zero. The plateau that follows is described as phase 2. In phase 4 the AP returns to an RMP of -80 to -90 mV. 16. Which statement regarding the autonomic nervous system's role in the regulation of heart rate is true? a. Parasympathetic influences increase heart rate. b. Sympathetic influences are predominantly present. c. Parasympathetic influences are only compensatory. d. Both sympathetic and parasympathetic influences are normally active. ANS: D The parasympathetic nervous system and the sympathetic nervous system operate to create a balance between relaxation and fight-or-flight readiness. They affect cardiovascular function by slowing the heart rate during periods of calm and increasing it in response to sympathetic stimulation. 17. A patient is admitted to the critical care unit with a diagnosis of acute myocardial infarction. The monitor pattern reveals bradycardia. The patient weight is 70 kg and height is 5 feet, 5 inches tall. Based on the above information; occlusion of which coronary artery most likely resulted in bradycardia from sinoatrial node ischemia? a. Right c. Circumflex b. Left anterior descending d. Dominant ANS: A The right coronary artery provides the blood supply to the sinoatrial and AV nodes in more than half the population. The left coronary artery is a short but important artery that divides into two large arteries, the left anterior descending and the circumflex arteries. These vessels serve the left atrium and most of the left ventricle. The term dominant coronary artery is used to describe the artery that supplies the posterior part of the heart. 18. An echocardiogram reveals an ejection fraction of 55%. On the basis of this information, the patient's cardiac function is a. adequate. c. moderately decreased. b. mildly decreased. d. severely decreased. ANS: A Ejection fraction is expressed as a percent, with normal being at least greater than 50%. An ejection fraction of less than 35% indicates poor ventricular function (as in cardiomyopathy), poor ventricular filling, obstruction to outflow (as in some valve stenosis conditions), or a combination of these. 19. Which of the following values reflects a normal cardiac output at rest? a. 2.5 L/min c. 7.3 L/min b. 5.8 L/min d. 9.6 L/min ANS: B Cardiac output is normally expressed in liters per minute (L/min). The normal cardiac output in the human adult is approximately 4 to 8 L/min. It is approximately 4 to 6 L/min at rest and increases with exercise. 20. A patient is admitted to the critical care unit with right- and left-sided heart failure. The nurse's assessment reveals that the patient has 3+ pitting edema on the sacrum, blood pressure of 176/98 mm Hg, and bilateral crackles in the lungs. The patient is experiencing shortness of breath and chest discomfort. On the basis of this information, how would the nurse evaluate the patient's preload status? a. The patient is hypovolemic and has too little preload. b. The patient is experiencing CHF and has too little preload. c. The patient is experiencing heart failure and has too much preload. d. The patient is hypertensive and the preload is not a factor. ANS: C Whereas a patient with hypovolemia has too little preload, a patient with heart failure has too much preload. 21. A patient is admitted to the critical care unit with right- and left-sided heart failure. The nurse's assessment reveals that the patient has 3+ pitting edema on the sacrum, blood pressure of 176/98 mm Hg, and bilateral crackles in the lungs. The patient is experiencing shortness of breath and chest discomfort. Increased afterload is probably present related to the patient's blood pressure. Which therapeutic measure will most likely decrease afterload in this patient? a. Administration of vasodilators c. Elevation of extremities b. Placement in high Fowler position d. Increasing intravenous fluids ANS: A Therapeutic management to decrease afterload is aimed at decreasing the work of the heart with the use of vasodilators. Placing the patient in high Fowler position will cause an increase in the workload of the heart. Elevation of the extremities will ease the venous return back to the heart. Increasing IV fluids will cause an increased workload on the heart. 1. Which of the following conditions is usually associated with clubbing? a. Central cyanosis c. Carbon monoxide poisoning b. Peripheral cyanosis d. Acute hypoxemia ANS: A Clubbing in the nail bed is a sign associated with longstanding central cyanotic heart disease or pulmonary disease with hypoxemia. Peripheral cyanosis, a bluish discoloration of the nail bed, is seen more commonly. Peripheral cyanosis results from a reduction in the quantity of oxygen in the peripheral extremities from arterial disease or decreased cardiac output. Central cyanosis is a bluish discoloration of the tongue and sublingual area. Multiracial studies indicate that the tongue is the most sensitive site for observation of central cyanosis. 2. The abdominojugular reflux test determines the presence of a. right ventricular failure. c. liver failure. b. hypoxemia. d. pitting edema. ANS: A The abdominojugular reflux sign can assist with the diagnosis of right ventricular failure. A positive abdominojugular reflux sign is an increase in the jugular venous pressure (CVP equivalent) of greater than 3 cm sustained for at least 15 seconds. 3. The purpose of the Allen test is to a. assess adequate blood flow through the ulnar artery. b. occlude the brachial artery and evaluate hypoxemia to the hand. c. test the patency of an internal graft. d. determine the size of needle to be used for puncture. ANS: A The Allen test assesses the adequacy of blood flow to the hand through the ulnar artery. 4. Evaluation of arterial circulation to an extremity is accomplished by assessing which of the following? a. Homans sign c. Peripheral edema b. Skin turgor d. Capillary refill ANS: D Capillary refill assessment is a maneuver that uses the patient's nail beds to evaluate both arterial circulation to the extremity and overall perfusion. The severity of arterial insufficiency is directly proportional to the amount of time necessary to re-establish flow and color. 5. When checking the patient's back, the nurse pushes her thumb into the patient's sacrum. An indentation remains. The nurse charts that the patient has a. sacral compromise. c. pitting edema. b. delayed skin turgor. d. dehydration. ANS: C Pitting edema occurs when an impression is left in the tissue when the thumb is removed. The dependent tissues within the legs and sacrum are particularly susceptible. Edema may be dependent, unilateral, or bilateral and pitting or nonpitting. 6. An assessment finding of pulsus alternans may indicate evidence of a. left-sided heart failure. c. pulmonary embolism. b. jugular venous distention. d. myocardial ischemia. ANS: A Pulsus alternans describes a regular pattern of pulse amplitude changes that alternate between stronger and weaker beats. This finding is suggestive of end-stage left ventricular heart failure. 7. The presence of a carotid or femoral bruit may be evidence of a. left-sided heart failure. b. blood flow through a partially occluded vessel. c. the early onset of pulmonary embolism. d. myocardial rupture. ANS: B A bruit is an extracardiac vascular sound that results from blood flow through a tortuous or partially occluded vessel. 8. A 68-year-old patient is admitted to the critical care unit with reports of midchest pressure radiating into the jaw and shortness of breath when walking up stairs. The patient is admitted with a diagnosis of "rule out myocardial infarction." The history portion of the assessment should be guided by a. medical history. c. presenting symptoms. b. history of prior surgeries. d. a review of systems. ANS: C For a patient in acute distress, the history taking is shortened to just a few questions about the patient's chief complaint, precipitating events, and current medications. For a patient who is not in obvious distress, the history focuses on the following four areas: review of the patient's present illness; overview of the patient's general cardiovascular status; review of the patient's general health status, including family history of coronary artery disease (CAD), hypertension, diabetes, peripheral arterial disease, or stroke; and survey of the patient's lifestyle, including risk factors for CAD. 9. A 68-year-old patient is admitted to the critical care unit with reports of midchest pressure radiating into the jaw and shortness of breath when walking up stairs. The patient is admitted with a diagnosis of "rule out myocardial infarction." When inspecting the patient, the nurse notes that the patient needs to sit in a high Fowler position to breathe. This may indicate a. pericarditis. c. heart failure. b. anxiety. d. angina. ANS: C Sitting upright to breathe may be necessary for the patient with acute heart failure, and leaning forward may be the least painful position for a patient with pericarditis. 10. An 82-year-old patient is admitted into the critical care unit with a diagnosis of left-sided heart failure related to mitral stenosis. Physical assessment findings reveal tachycardia with an S3 and a 3/6 systolic murmur. The nurse knows that the presence of an S3 heart sound is a. normal for a person this age. b. a ventricular gallop. c. a systolic sound. d. heard best with the diaphragm of the stethoscope. ANS: B The abnormal heart sounds are labeled the third heart sound (S3) and the fourth heart sound (S4) and are referred to as gallops when auscultated during an episode of tachycardia. Not unexpectedly, the development of an S3 heart sound is strongly associated with elevated levels of brain natriuretic peptide. 11. An 82-year-old patient is admitted into the critical care unit with a diagnosis of left-sided heart failure related to mitral stenosis. Physical assessment findings reveal tachycardia with an S3 and a 3/6 systolic murmur. The grading of a murmur as a 3/6 refers to which of the following characteristics of murmurs? a. Intensity c. Timing b. Quality d. Pitch ANS: A Intensity, or the "loudness," is graded on a scale of 1 to 6; the higher the number, the louder the murmur. 2. An 82-year-old patient is admitted into the critical care unit with a diagnosis of left-sided heart failure related to mitral stenosis. Physical assessment findings reveal tachycardia with an S3 and a 3/6 systolic murmur. Which of the following descriptions best describes the murmur heard with mitral stenosis? a. High-pitched systolic sound c. High-pitched diastolic sound b. Medium-pitched systolic sound d. Low-pitched diastolic sound ANS: D Mitral stenosis describes a narrowing of the mitral valve orifice. This produces a low-pitched murmur, which varies in intensity and harshness depending on the degree of valvular stenosis. It occurs during diastole, is auscultated at the mitral area (fifth ICS, midclavicular line), and does not radiate. 13. _____ are created by the turbulence of blood flow through a vessel caused by constriction of the blood pressure cuff. a. Korotkoff sounds c. Murmurs b. Pulse pressures d. Gallops ANS: A Korotkoff sounds are the sounds created by turbulence of blood flow within a vessel caused by constriction of the blood pressure cuff. Pulse pressure describes the difference between systolic and diastolic values. The normal pulse pressure is 40 mm Hg. Abnormal heart sounds are known as the third heart sound (S3) and the fourth heart sound (S4); they are referred to as gallops when auscultated during an episode of tachycardia. Murmurs are produced by turbulent blood flow through the chambers of the heart, from forward flow through narrowed or irregular valve openings, or backward regurgitate flow through an incompetent valve. 14. Abnormal heart sounds are labeled S3 and S4 and are referred to as __________ when auscultated during a tachycardic episode. a. Korotkoff sounds c. murmurs b. pulse pressure d. gallops ANS: D Abnormal heart sounds are known as the third heart sound (S3) and the fourth heart sound (S4); they are referred to as gallops when auscultated during an episode of tachycardia. Murmurs are produced by turbulent flood flow through the chambers of the heart, from forward flow through narrowed or irregular valve openings, or backward regurgitate flow through an incompetent valve. Korotkoff sounds are the sounds created by turbulence of blood flow within a vessel caused by constriction of the blood pressure cuff. Pulse pressure describes the difference between systolic and diastolic values. A normal pulse pressure is 40 mm Hg. 15. A heart murmur is described as blowing, grating, or harsh. This description would fall under which criteria? a. Intensity c. Timing b. Quality d. Pitch ANS: B Quality is whether the murmur is blowing, grating, or harsh. Intensity is the loudness graded on a scale of 1 through 6; the higher the number, the louder is the murmur. Timing is the place in the cardiac cycle (systole/diastole). Pitch is whether the tone is high or low. 16. The nurse assesses the dorsalis pedis and posterior tibial pulses as weak and thready. Indicate the correct documentation for the pulse volume that the nurse would use. a. 0 c. 2+ b. 1+ d. 3+ ANS: B Pulse volumes are 0, not palpable; 1+, faintly palpable (weak and thready); 2+, palpable (normal pulse); and 3+, bounding (hyperdynamic pulse). 17. A nurse palpates the descending aorta and feels a strong, bounding pulse. The nurse reports the findings to the physician because the results suggest a. decreased cardiac output. c. an aneurysm. b. increased cardiac output. d. aortic insufficiency. ANS: C When the patient is in the supine position, the abdominal aortic pulsation is located in the epigastric area and can be felt as a forward movement when firm fingertip pressure is applied above the umbilicus. An abnormally strong or bounding pulse suggests the presence of an aneurysm or an occlusion distal to the examination site. If it is prominent or diffuse, the pulsation may indicate an abdominal aneurysm. A diminished or absent pulse may indicate low CO, arterial stenosis, or occlusion proximal to the site of the examination. 18. A nurse from the ICU receives a report from the ED nurse on a patient that includes a diagnosis of syncope unknown etiology. Orthostatic VS lying: 110/80 mm/Hg; sitting: 100/74 mm/Hg; standing: 92/40 mm/Hg. Based on this information, the nurse should monitor the patient's a. breathing. c. peripheral pulses. b. dietary intake. d. activity. ANS: D Postural (orthostatic) hypotension occurs when the systolic blood pressure drops by 10 to 20 mm Hg or the diastolic blood pressure drops by 5 mm Hg after a change from the supine posture to the upright posture. This is usually accompanied by dizziness, lightheadedness, or syncope. If a patient experiences these symptoms, it is important to complete a full set of postural vital signs before increasing the patient's activity level. 19. A patient's blood pressure is 90/72 mm Hg. What is the patient's pulse pressure? a. 40 mm Hg c. 18 mm Hg b. 25 mm Hg d. 12 mm Hg ANS: C Pulse pressure describes the difference between systolic and diastolic values. The normal pulse pressure is 40 mm Hg (i.e., the difference between an SBP of 120 mm Hg and a DBP of 80 mm Hg). A patient with a blood pressure of 90/72 mm Hg has a pulse pressure of 18 mm Hg. 20. A sudden increase in left atrial pressure, acute pulmonary edema, and low cardiac output, caused by the ventricle contracting during systole, are all characteristics of a. acute mitral regurgitation. c. chronic mitral regurgitation. b. aortic insufficiency. d. pericardial friction rub. ANS: A Acute mitral regurgitation occurs when the ventricle contracts during systole and a jet of blood is sent in a retrograde manner to the left atrium, causing a sudden increase in left atrial pressure, acute pulmonary edema, and low CO and leading to cardiogenic shock. Chronic mitral regurgitation is auscultated in the mitral area and occurs during systole. It is high pitched and blowing, although the pitch and intensity vary, depending on the degree of regurgitation. As mitral regurgitation progresses, the murmur radiates more widely. Aortic insufficiency is an incompetent aortic valve. If the valve cusps do not maintain this seal, the sound of blood flowing back into the left ventricle during diastole is heard as a decrescendo, high-pitched, blowing murmur. A pericardial friction rub is a sound that can occur within 2 to 7 days after a myocardial infarction. The friction rub results from pericardial inflammation (pericarditis). Classically, a pericardial friction rub is a grating or scratching sound that is both systolic and diastolic, corresponding to cardiac motion within the pericardial sac. 21. A patient was admitted to the ICU 3 days ago with a diagnosis of myocardial infarction. The patient is complaining of increased chest pain when coughing, swallowing, and changing positions. The nurse hears a systolic scratching sound upon auscultation of the apical pulse. The nurse notifies the physician. Based on the symptoms, the physician suspects a(n) a. acute mitral regurgitation. c. chronic mitral regurgitation. b. aortic insufficiency. d. pericardial friction rub. ANS: D A pericardial friction rub is a sound that can occur within 2 to 7 days after a myocardial infarction. The friction rub results from pericardial inflammation (pericarditis). Classically, a pericardial friction rub is a grating or scratching sound that is both systolic and diastolic, corresponding to cardiac motion within the pericardial sac. Acute mitral regurgitation occurs when the ventricle contracts during systole and a jet of blood is sent in a retrograde manner to the left atrium, causing a sudden increase in left atrial pressure, acute pulmonary edema, and low CO and leading to cardiogenic shock. Chronic mitral regurgitation is auscultated in the mitral area and occurs during systole. It is high pitched and blowing, although the pitch and intensity vary, depending on the degree of regurgitation. As mitral regurgitation progresses, the murmur radiates more widely. Aortic insufficiency is an incompetent aortic valve. If the valve cusps do not maintain this seal, the sound of blood flowing back into the left ventricle during diastole is heard as a decrescendo, high-pitched, blowing murmur. 22. During a history examination, a patient tells the nurse, "The cardiologist says I have a leaking valve." The nurse documents that the patient has a history of a. acute mitral regurgitation. c. chronic mitral regurgitation. b. aortic insufficiency. d. pericardial friction rub. ANS: B Aortic insufficiency is an incompetent aortic valve. If the valve cusps do not maintain this seal, the sound of blood flowing back into the left ventricle during diastole is heard as a decrescendo, high-pitched, blowing murmur. A pericardial friction rub is a sound that can occur within 2 to 7 days after a myocardial infarction. The friction rub results from pericardial inflammation (pericarditis). Classically, a pericardial friction rub is a grating or scratching sound that is both systolic and diastolic, corresponding to cardiac motion within the pericardial sac. Acute mitral regurgitation occurs when the ventricle contracts during systole and a jet of blood is sent in a retrograde manner to the left atrium, causing a sudden increase in left atrial pressure, acute pulmonary edema, and low CO and leading to cardiogenic shock. Chronic mitral regurgitation is auscultated in the mitral area and occurs during systole. It is high pitched and blowing, although the pitch and intensity vary, depending on the degree of regurgitation. As mitral regurgitation progresses, the murmur radiates more widely. 23. A patient was admitted on the night shift with a diagnosis of acute myocardial infarction. Upon auscultation, the nurse hears a harsh, holosystolic murmur along the left sternal border. The nurse notifies the physician immediately because the symptoms indicate the patient has developed a. papillary muscle rupture. c. ventricular septal rupture. b. tricuspid stenosis. d. pericardial friction rub. ANS: C Ventricular septal rupture is a new opening in the septum between the two ventricles. It creates a harsh, holosystolic murmur that is loudest (by auscultation) along the left sternal border. Papillary muscle rupture is auscultation of a new, high-pitched, holosystolic, blowing murmur at the cardiac apex. Tricuspid stenosis is a quiet murmur that becomes louder with inspiration and is located in the epigastrium area. A pericardial friction rub is a sound that can occur within 2 to 7 days after a myocardial infarction. The friction rub results from pericardial inflammation (pericarditis). Classically, a pericardial friction rub is a grating or scratching sound that is both systolic and diastolic, corresponding to cardiac motion within the pericardial sac. 1. Which of the following describe(s) S1, the first heart sound? (Select all that apply.) a. It is associated with closure of the mitral and tricuspid valves. b. It is a high-pitched sound. c. It can be heard most clearly with the diaphragm of the stethoscope. d. The best listening point is in the aortic area. e. The "split" sound can best be detected in the tricuspid area. ANS: A, B, C, E S1 is the sound associated with mitral and tricuspid valve closure and is heard most clearly in the mitral and tricuspid areas. S1 sounds are high pitched and heard best with the diaphragm of the stethoscope. 2. Heart murmurs are characterized by which of the following criteria? (Select all that apply.) a. Intensity b. Location c. Quality d. Pitch e. Pathologic cause ANS: A, B, C, D Murmurs are characterized by specific criteria: Timing is the place in the cardiac cycle (systole/diastole). Location is where it is auscultated on the chest wall (mitral or aortic area). Radiation is how far the sound spreads across chest wall. Quality is whether the murmur is blowing, grating, or harsh. Pitch is whether the tone is high or low. Intensity is the loudness is graded on a scale of 1 through 6; the higher the number, the louder the murmur. 1. A patient with a serum potassium level of 6.8 mEq/L may exhibit electrocardiographic changes of a. a prominent U wave. c. a narrowed QRS. b. tall, peaked T waves. d. sudden ventricular dysrhythmias. ANS: B Normal serum potassium levels are 3.5 to 4.5 mEq/L. Tall, narrow peaked T waves are usually, although not uniquely, associated with early hyperkalemia and are followed by prolongation of the PR interval, loss of the P wave, widening of the QRS complex, heart block, and asystole. Severely elevated serum potassium (greater than 8 mEq/L) causes a wide QRS tachycardia. 2. A patient with heart failure may be at risk for hypomagnesemia as a result of a. pump failure. c. fluid overload. b. diuretic use. d. hemodilution. ANS: B Hypomagnesemia can be caused by diuresis. Diuretic use with heart failure often contributes to low serum magnesium levels. 3. Which of the following diagnostic tests is most effective for measuring overall heart size? a. Twelve-lead electrocardiography c. Chest radiography b. Echocardiography d. Vectorcardiography ANS: C Chest radiography is the oldest noninvasive method for visualizing images of the heart, and it remains a frequently used and valuable diagnostic tool. Information about cardiac anatomy and physiology can be obtained with ease and safety at a relatively low cost. Radiographs of the chest are used to estimate the cardiothoracic ratio and measure overall heart size. 4. ST segment monitoring for ischemia has gained increasing importance with the advent of thrombolytic therapy. The most accurate method for monitoring the existence of true ischemic changes is a. T-wave inversion in leads overlying the ischemia. b. ST segment depression in leads overlying the ischemia. c. adjusting the gain control on bedside monitoring for best visualization. d. 12-lead ECG for confirmation. ANS: D Cardiac biomarkers are proteins that are released from damaged myocardial cells. The initial elevation of cTnI, cTnT, and CK-MB occurs 3 to 6 hours after the acute myocardial damage. This means that if an individual comes to the emergency department as soon as chest pain is experienced, the biomarkers will not have risen. For this reason, it is clinical practice to diagnose an acute myocardial infarction by 12-lead electrocardiography and clinical symptoms without waiting for elevation of cardiac biomarkers. 5. Which of the following criteria are representative of the patient in normal sinus rhythm? a. Heart rate, 64 beats/min; rhythm regular; PR interval, 0.10 second; QRS, 0.04 second b. Heart rate, 88 beats/min; rhythm regular; PR interval, 0.18 second; QRS, 0.06 second c. Heart rate, 54 beats/min; rhythm regular; PR interval, 0.16 second; QRS, 0.08 second d. Heart rate, 92 beats/min; rhythm irregular; PR interval, 0.16 second; QRS, 0.04 second ANS: B The parameters for normal sinus rhythm are heart rate, 60 to 100 beats/min; rhythm, regular; PR interval, 0.12 to 0.20 second; and QRS, 0.06 to 0.10 second. 6. The major key to the clinical significance of atrial flutter is the a. atrial rate. c. PR interval. b. ventricular response rate. d. QRS duration. ANS: B The major factor underlying atrial flutter symptoms is the ventricular response rate. If the atrial rate is 300 and the atrioventricular (AV) conduction ratio is 4:1, the ventricular response rate is 75 beats/min and should be well tolerated. If, on the other hand, the atrial rate is 300 beats/min but the AV conduction ratio is 2:1, the corresponding ventricular rate of 150 beats/min may cause angina, acute heart failure, or other signs of cardiac decompensation. 7. A characteristic event in junctional dysrhythmias is a. irregular rhythm. b. rapid depolarization to the ventricles. c. the spread of the impulse in two directions at once. d. a widened QRS. ANS: C After an ectopic impulse arises in the junction, it spreads in two directions at once. One wave of depolarization spreads upward into the atria and depolarizes them, causing the recording of a P wave on the electrocardiogram. At the same time, another wave of depolarization spreads downward into the ventricles through the normal conduction pathway, producing a normal QRS complex. 8. When assessing a patient with PVCs, the nurse knows that the ectopic beat is multifocal because it appears a. in various shapes in the same lead. c. to widen the QRS width. b. with increasing frequency. d. in a specific pattern in the same lead. ANS: A If the ventricular ectopic beats are of various shapes in the same lead, they are multifocal. Multifocal ventricular ectopics are more serious than unifocal ventricular ectopics because they indicate a greater area of irritable myocardial tissue and are more likely to deteriorate into ventricular tachycardia or fibrillation. 9. A patient with ventricular fibrillation (VF) is a. hypertensive. c. diaphoretic. b. bradypneic. d. pulseless. ANS: D In VF, the patient does not have a pulse, no blood is being pumped forward, and defibrillation is the only definitive therapy. No forward flow of blood or palpable pulse is present in VF. 10. Which portion of the ECG is most valuable in diagnosing atrioventricular (AV) conduction disturbances? a. P wave c. QRS complex b. PR interval d. QT interval ANS: B The PR interval is an indicator of atrioventricular nodal function. The P wave represents atrial depolarization. The QRS complex represents ventricular depolarization, corresponding to phase 0 of the ventricular action potential. The QT interval is measured from the beginning of the QRS complex to the end of the T wave and indicates the total time interval from the onset of depolarization to the completion of repolarization. 11. Which of the following findings would be indicative reasons to abort an exercise stress test? a. Ventricular axis of +90 c. Inverted U wave b. Increase in blood pressure d. ST segment depression or elevation ANS: D Signs that can alert the nurse to stop the test include ST segment elevation equal to or greater than 1.0 mm (one small box) or ST depression equal to or greater than 2.0 mm (2 small boxes). Blood pressure is expected to rise during exercise, but a systolic blood pressure greater than 250 mm Hg or a diastolic blood pressure greater than 115 mm Hg is considered high enough to stop the test. Parameters for ventricular axis in degrees are ?2-30° to +90°. Left-axis deviation is present if the axis falls between ?2-30° and ?2-90°. 12. The rationale for giving the patient additional fluids after a cardiac catheterization is that a. fluids help keep the femoral vein from clotting at the puncture site. b. the patient had a nothing-by-mouth order before the procedure. c. the radiopaque contrast acts as an osmotic diuretic. d. fluids increase cardiac output. ANS: C Fluid is given for rehydration because the radiopaque contrast acts as an osmotic diuretic. Fluid is also used to prevent contrast-induced nephropathy or damage to the kidney from the contrast dye used to visualize the heart structures. 13. Pulsus paradoxus may be seen on intra-arterial blood pressure monitoring when a. there is a decrease of more than 10 mm Hg in the arterial waveform before inhalation. b. there is a single, nonperfused beat. c. the waveform demonstrates tall, tented T waves. d. the pulse pressure is greater than 20 mm Hg on exhalation. ANS: A Pulsus paradoxus is a decrease of more than 10 mm Hg in the arterial waveform that occurs during inhalation. It is caused by a fall in CO as a result of increased negative intrathoracic pressure during inhalation. 14. When assessing the pulmonary arterial waveform, the nurse notices dampening. After tightening the stopcocks and flushing the line, the nurse decides to calibrate the transducer. What are two essential components included in calibration? a. Obtaining a baseline blood pressure and closing the transducer to air b. Leveling the air-fluid interface to the phlebostatic axis and opening the transducer to air c. Having the patient lay flat and closing the transducer to air d. Obtaining blood return on line and closing all stopcocks ANS: B Ensuring accuracy of waveform calibration of the system includes opening the transducer to air and leveling the air-fluid interface of the transducer to the phlebostatic axis. 15. The mean arterial pressure (MAP) is calculated by a. averaging three of the patient's blood pressure readings over a 6-hour period. b. dividing the systolic pressure by the diastolic pressure. c. adding the systolic pressure and two diastolic pressures and then dividing by 3. d. dividing the diastolic pressure by the pulse pressure. ANS: C The mean arterial pressure is one-third systole and two-thirds diastole. 16. The physiologic effect of left ventricular afterload reduction is a. decreased left atrial tension. c. increased filling pressures. b. decreased systemic vascular resistance. d. decreased cardiac output. ANS: B Afterload is defined as the pressure the ventricle generates to overcome the resistance to ejection created by the arteries and arterioles. After a decrease in afterload, wall tension is lowered. The technical name for afterload is systemic vascular resistance (SVR). Resistance to ejection from the right side of the heart is estimated by calculating the pulmonary vascular resistance (PVR). The PVR value is normally one-sixth of the SVR. 17. Contractility of the left side of the heart is measured by a. pulmonary artery wedge pressure. c. systemic vascular resistance. b. left atrial pressure. d. left ventricular stroke work index. ANS: D Contractility of the left side of the heart is measured by the left ventricular stroke work index. 18. Which of the following interventions should be strictly followed to ensure accurate cardiac output readings? a. Use 5 mL of iced injectate only. b. Inject the fluid into the pulmonary artery port only. c. Ensure a difference of at least 5° C between injectate temperature and the patient's body temperature. d. Administer the injectate within 4 seconds. ANS: D To ensure accurate readings, the difference between injectate temperature and body temperature must be at least 10° C, and the injectate must be delivered within 4 seconds, with minimal handling of the syringe to prevent warming of the solution. This is particularly important when iced injectate is used. 19. The value of SVO2 monitoring is to determine a. oxygen saturation at the capillary level. b. an imbalance between oxygen supply and metabolic tissue demand. c. the diffusion of gases at the alveolar capillary membrane. d. the predicted cardiac output for acute pulmonary edema. ANS: B Three of these factors (CO, Hgb, and Sao2) contribute to the supply of oxygen to the tissues. Tissue metabolism (Vo2) determines oxygen consumption or the quantity of oxygen extracted at tissue level that creates the demand for oxygen. 20. A 52-year-old patient presents to the emergency department with reports of substernal chest pain. A history is taken; serum creatine kinase (CK) and lactate dehydrogenase (LDH) isoenzymes and serum lipid studies are ordered, as is a 12-lead ECG. Which of the following results is most significant in diagnosing an MI during the first 12 hours of chest pain? a. ECG—inverted T waves c. Serum enzymes—elevated CK-MB b. Serum enzymes—elevated LDH4 d. Patient history—substernal chest pain ANS: C The creatine kinase (CK) muscle/brain (MB) biomarker (CK-MB) is released as a result of myocardial damage, and serum levels rise 4 to 8 hours after myocardial infarction (MI), peak at 15 to 24 hours, and remain elevated for 2 to 3 days. Serial samples are drawn routinely at 6- or 8-hour intervals, and three samples are usually sufficient to support or rule out the diagnosis of MI. 21. Which serum lipid value is a significant predictor of future acute MI in persons with established coronary artery atherosclerosis? a. High-density lipoprotein (HDL) c. Triglycerides b. Low-density lipoprotein (LDL) d. Very-low-density lipoprotein ANS: B Both the LDL-C and total serum cholesterol levels are directly correlated with risk for coronary artery disease, and high levels of each are significant predictors of future acute myocardial infarction in persons with established coronary artery atherosclerosis. LDL-C is the major atherogenic lipoprotein and thus is the primary target for cholesterol-lowering efforts. 22. Which of the ECG findings would be positive for an inferior wall MI? a. ST segment depression in leads I, aVL, and V2 to V4 b. Q waves in leads V1 to V2 c. Q waves in leads II, III, and aVF d. T-wave inversion in leads V4 to V6, I, and aVL ANS: C Abnormal Q waves develop in leads overlying the affected area. An inferior wall infarction is seen with changes in leads II, III, and aVF. Leads I and aVF are selected to detect a sudden change in ventricular axis. If ST segment monitoring is required, the lead is selected according to the area of ischemia. If the ischemic area is not known, leads V3 and III are recommended to detect ST segment ischemia. 23. A patient's bedside ECG strips show the following changes: increased PR interval; increased QRS width; and tall, peaked T waves. Vital signs are T 98.2° F; HR 118 beats/min; BP 146/90 mm Hg; and RR 18 breaths/min. The patient is receiving the following medications: digoxin 0.125 mg PO every day; D51/2 normal saline with 40 mEq potassium chloride at 125 mL/hr; Cardizem at 30 mg PO q8h; and aldosterone at 300 mg PO q12h. The physician is notified of the ECG changes. What orders should the nurse expect to receive? a. Change IV fluid to D51/2 normal saline and draw blood chemistry. b. Give normal saline with 40 mEq of potassium chloride over a 6-hour period. c. Hold digoxin and draw serum digoxin level. d. Hold Cardizem and give 500 mL normal saline fluid challenge over a 2-hour period. ANS: A The electrocardiographic (ECG) changes are most consistent with hyperkalemia. Removing the potassium from the intravenous line and drawing laboratory values to check the potassium level is the best choice with the least chance of further harm. Digoxin toxicity can be suspected related to the prolonged PR interval, but hyperkalemia explains all the ECG changes. The patient is not hypotensive or bradycardic, so holding the Cardizem is not indicated. 24. A patient with a potassium level of 2.8 mEq/L is given 60 mEq over a 12-hour period, and a repeat potassium level is obtained after the bolus. The current potassium level is 2.9 mEq/L. Which of the following should now be considered? a. Stopping the patient's Aldactone c. Rechecking the potassium level b. Drawing a serum magnesium level d. Monitoring the patient's urinary output ANS: B A total serum magnesium concentration below 1.5 mEq/L defines hypomagnesemia. It is commonly associated with other electrolyte imbalances, most notably alterations in potassium, calcium, and phosphorus. Low serum magnesium levels can result from many causes. 25. Which of the following cardiac enzymes is a highly specific biomarker for myocardial damage? a. CK-MB c. Troponin T b. Troponin I d. LDH ANS: B Because cTnI is found only in cardiac muscle, it is a highly specific biomarker for myocardial damage, considerably more specific than CK-MB. As a consequence, patients with a positive cTnI result and a negative CK-MB result usually rule in an acute myocardial infarction (MI). A negative cTnI result that remains negative many hours after an episode of chest pain is a strong indicator that the patient is not experiencing an acute MI. Even with a negative cTnI result, symptoms of chest pain still indicate that the patient should have a comprehensive cardiac evaluation to determine if there is underlying CAD present that may later lead to complications. 26. The physician anticipates the CVC dwelling time to be 10 to 20 days. The nurse anticipates that the CVC will be placed in the a. SC vein. c. EJ vein. b. IJ vein. d. femoral vein. ANS: A If the anticipated central venous catheter (CVC) dwelling time is prolonged more than 5 days, the subcutaneous (SC) site is preferred. The SC position has the lowest infection rate and produces the least patient discomfort from the catheter. The internal jugular (IJ) vein is the most frequently used access site for CVC insertion. Compared with the other thoracic veins, it is the easiest to canalize. If the IJ vein is not available, the external jugular (EJ) vein may be accessed, although blood flow is significantly higher in the IJ vein, making it the preferred site. This may be the reason why catheter-related infections are higher in the IJ than the SC position for indwelling catheters left in place for more than 4 days. The femoral vein is considered the easiest cannulation site because there are no curves in the insertion route. Because there is a higher rate of nosocomial infection with femoral catheters, this site is not recommended. 27. When comparing a portable chest radiograph taken in an intensive care unit bed with one taken with the patient upright in the radiology department, one significant difference is that the a. portable chest radiograph is usually clearer. b. one in the intensive care unit is considered a posterior view. c. portable chest radiograph magnifies some thoracic structures and decreases the sharpness of the structures. d. departmental chest radiograph enlarges some thoracic structures. ANS: C In the supine radiograph with the patient lying flat on the bed, the x-ray tube can be only approximately 36 inches from the patient's chest because of ceiling height and x-ray equipment construction. This results in a lower quality film from a diagnostic standpoint because the images of the heart and great vessels are magnified and are not as sharply defined. 28. A patient asks why he had to take a deep breath when the radiology technician took his chest radiograph. Which of the following would be the best response? a. It gets the chest wall closer to the machine. b. Lungs filled with air give a clearer picture. c. It decreases the error caused by motion. d. It makes the heart appear larger. ANS: B A radiograph is taken when the patient has taken a deep breath (inspiration). During exhalation, the lungs are less full of air, which can make the lung tissue appear "cloudy" as if there is additional lung water. The heart also appears larger during exhalation. This could lead to an erroneous diagnosis of heart failure. 29. The most common complication of a central venous catheter (CVC) is a. air embolus. c. thrombus formation. b. infection. d. pneumothorax. ANS: B Infection related to the use of CVCs is a major problem. The incidence of infection strongly correlates with the length of time the CVC has been inserted, with longer insertion times leading to a higher infection rate. The risk of air embolus, although uncommon, is always present for a patient with a central venous line in place. Air can enter during insertion through a disconnected or broken catheter by means of an open stopcock, or air can enter along the path of a removed CVC. Unfortunately, clot formation (thrombus) at the CVC site is common. Thrombus formation is not uniform; it may involve development of a fibrin sleeve around the catheter, or the thrombus may be attached directly to the vessel wall. Pneumothorax has a higher occurrence during placement of a CVC than during removal. 30. A physician orders removal of the central venous catheter (CVC) line. The patient has a diagnosis of heart failure with chronic obstructive pulmonary disease. The nurse would place the patient in what position for this procedure? a. Supine in bed c. Flat in bed b. Supine in a chair d. Reverse Trendelenburg position ANS: A Recommended techniques to avoid air embolus during CVC removal include removing the catheter when the patient is supine in bed (not in a chair) and placing the patient flat or in the reverse Trendelenburg position if the patient's clinical condition permits this maneuver. Patients with heart failure, pulmonary disease, and neurologic conditions with raised intracranial pressure should not be placed flat. 31. Mechanical contraction of the heart occurs during which of the following phases of the cardiac cycle? a. Phase 0 c. Phase 3 b. Phase 2 d. Phase 4 ANS: B During phases 1 and 2, an electrical plateau is created, and during this plateau, mechanical contraction occurs. Because there is no significant electrical change, no waveform appears on the electrocardiogram (ECG). During phase 0 (depolarization), the electrical potential changes rapidly from a baseline of ?2-90 mV to +20 mV and stabilizes at about 0 mV. Because this is a significant electrical change, it appears as a wave on the ECG as the QRS. During phase 3 (repolarization), the electrical potential again changes, this time a little more slowly, from 0 mV back to ?2-90 mV. This is another major electrical event and is reflected on the ECG as a T wave. During phase 4 (resting period), the chemical balance is restored by the sodium pump, but because positively charged ions are exchanged on a one-for-one basis, no electrical activity is generated, and no visible change occurs on the ECG tracing. 32. The P wave represents which of the following? a. Atrial contraction c. Sinus node discharge b. Atrial depolarization d. Ventricular contraction ANS: B The P wave is an electrical event and represents atrial depolarization. Atrial contraction should accompany the P wave but does not always. The sinus node discharge is too faint to be recorded on the surface electrocardiogram. Ventricular contraction usually accompanies the QRS complex. 33. Why is the measurement of the QT interval important? a. It represents ventricular depolarization. b. It represents ventricular contraction. c. An increasing QT interval increases the risk of torsades de pointes. d. A decreasing QT interval increases the risk of torsades de pointes. ANS: C A prolonged QT interval is significant because it can predispose the patient to the development of polymorphic ventricular tachycardia, known also as torsades de pointes. A long QT interval can be congenital, as a result of genetic inheritance, or it can be acquired from an electrolyte imbalance or medications. 34. Which lead is best to monitor a patient? a. Varies based on the patient's clinical condition and recent clinical history b. Lead MCL1 c. Lead V1 d. Lead II ANS: A The selection of an electrocardiographic monitoring lead is not a decision to be made casually or according to habit. The monitoring lead should be chosen with consideration of the patient's clinical condition and recent clinical history. If the monitored heart has a normal electrical axis, lead II displays a waveform that is predominantly upright, with a positive P wave and positive QRS waveform. P waves are usually easy to identify in lead II, and it is recommended for monitoring of atrial dysrhythmias. However, it is difficult to identify right bundle branch block (RBBB) and left bundle branch block (LBBB). Lead V1 is the optimal lead to select if the critical care nurse needs to analyze ventricular ectopy. V1 provides information to facilitate differentiation between RBBB versus LBBB pattern or distinguish between ventricular tachycardia and supraventricular tachycardia with aberrant conduction, determine whether premature ventricular contractions originate in the right or left ventricle, and clarify when ST segment changes are caused by the RBBB and when they are the result of ischemia. Lead V1 is excellent for this purpose. MCL1 is an uncommon lead choice today. It is used only if monitoring with a three-lead system such as on a transport monitor. 35. When performing a 12-lead ECG, how many wires are connected to the patient? a. 3 c. 10 b. 5 d. 12 ANS: C The standard 12-lead electrocardiogram provides a picture of electrical activity in the heart using 10 different electrode positions to create 12 unique views of electrical activity occurring within the heart. Fours wires are applied to the extremities to produce leads I, II, III, aVR, aVL, and aVF. Six wires are attached to the V1 to V6 chest lead positions. 36. A patient returns from the cardiac catheterization laboratory after angioplasty and stent placement (ECG changes had indicated an inferior wall myocardial infarction in progress). Which lead would best monitor this patient? a. Varies based on the patient's clinical condition and recent clinical history b. Lead MCL1 c. Lead V1 d. Lead II ANS: B If the monitored heart has a normal electrical axis, lead II displays a waveform that is predominantly upright, with a positive P wave and positive QRS waveform. P waves are usually easy to identify in lead II, and it is recommended for monitoring of atrial dysrhythmias. However, it is difficult to identify right bundle branch block (RBBB) and left bundle branch block (LBBB). The selection of an electrocardiographic monitoring lead is not a decision to be made casually or according to habit. The monitoring lead should be chosen with consideration of the patient's clinical condition and recent clinical history. Lead V1 is the optimal lead to select if the critical care nurse needs to analyze ventricular ectopy. V1 provides information to facilitate differentiation between RBBB versus LBBB pattern or distinguish between ventricular tachycardia and supraventricular tachycardia with aberrant conduction; determine whether premature ventricular contractions originate in the right or left ventricle, and clarify when ST segment changes are caused by the RBBB and when they are the result of ischemia. Lead V1 is excellent for this purpose. MCL1 is an uncommon lead choice today. It is used only if monitoring with a three-lead system such as on a transport monitor. 37. The patient's admitting 12-lead ECG shows peaked P waves. Which of the following admitting diagnoses could be responsible for this finding? a. Mitral stenosis c. Ischemia b. Pulmonary edema d. Pericarditis ANS: B Tall, peaked P waves occur in right atrial hypertrophy and are referred to as P pulmonale because this condition is often the result of chronic pulmonary disease. Ischemia occurs when the delivery of oxygen to the tissues is insufficient to meet metabolic demand. Cardiac ischemia in an unstable form occurs because of a sudden decrease in supply, such as when the artery is blocked by a thrombus or when coronary artery spasm occurs. If the pulmonary edema is caused by heart failure, sometimes described as hydrostatic pulmonary edema, the fluid may be in a "bat-wing" distribution, with the white areas concentrated in the hilar region (origin of the major pulmonary vessels). However, as the heart failure progresses, the quantity of fluid in the alveolar spaces increases, and the white, fluffy appearance is seen throughout the lung. Pericarditis is inflammation of the sac around the heart. 38. A nurse is obtaining the history of a patient who reveals that he had an MI 5 years ago. When the admission 12-lead ECG is reviewed, Q waves are noted in leads V3 and V4 only. Which of the following conclusions is most consistent with this situation? a. The patient may have had a posterior wall MI. b. The patient must have had a right ventricular MI. c. The admission 12-lead ECG was done incorrectly. d. The patient may have had an anterior MI. ANS: D Not every acute myocardial infarction (MI) results in a pathologic Q wave on the 12-lead electrocardiogram (ECG). When the typical ECG changes are not present, the diagnosis depends on symptomatic clinical presentation, specific cardiac biomarkers (e.g., cTnI, cTnT, CK-MB), and non-ECG diagnostic tests such as cardiac catheterization. Anterior and posterior wall MIs have ST changes, not Q wave changes. 39. A new-onset MI can be recognized by which of the following ECG changes? a. Q waves c. Widened QRS b. Smaller R waves d. ST segment elevation ANS: D Any change from baseline is expressed in millimeters and may indicate myocardial ischemia (one small box equals 1 mm). ST segment elevation of 1 to 2 mm is associated with acute myocardial injury, preinfarction, and pericarditis. ST segment depression (decrease from baseline more of 1 to 2 mm) is associated with myocardial ischemia. Widened QRS complexes are indicative of ventricular depolarization abnormalities such as bundle branch blocks and ventricular dysrhythmias. Q waves and smaller R waves are indications usually present 24 hours to 1 week after the myocardial infarction is completely evolved; they represent necrosis. 40. To accurately measure the heart rate of a patient in normal sinus rhythm, which technique would be the most accurate? a. The number of R waves in a 6-second strip b. The number of large boxes in a 6-second strip c. The number of small boxes between QRS complexes divided into 1500 d. The number of large boxes between consecutive R waves divided into 300 ANS: C Calculation of heart rate if the rhythm is regular may be done using the following methods. Method 1: number of RR intervals in 6 seconds multiplied by 10 (e.g., 8 × 10 = 80/min). Method 2: number of large boxes between QRS complexes divided into 300 (e.g., 300 ÷ 4 = 75/min). Method 3: number of small boxes between QRS complexes divided into 1500 (e.g., 1500 ÷ 18 = 84/min). 41. What is the initial intervention in a patient with sinus tachycardia with the following vital signs: HR, 136 beats/min; BP, 102/60 mm Hg; RR, 24 breaths/min; T, 99.2° F; SpO2, 94% on oxygen 2 L/min by nasal cannula? a. Stat adenosine to decrease heart rate b. Identification and correction of the cause of the increased heart rate c. Sublingual nitroglycerine 0.4 mg d. Lidocaine 75 mg IV push ANS: B Sinus tachycardia can be caused by a wide variety of factors, such as exercise, emotion, pain, fever, hemorrhage, shock, heart failure, and thyrotoxicosis. Illegal stimulant drugs such as cocaine, "ecstasy," and amphetamines can raise the resting heart rate significantly. Many medications used in critical care can also cause sinus tachycardia; common culprits are aminophylline, dopamine, hydralazine, atropine, and catecholamines such as epinephrine. This patient has a stable heart rate and SpO2; therefore, there is time to identify the cause of the sinus tachycardia. Lidocaine is indicated for ventricular dysrhythmias. Nitroglycerine is not indicated because the patient is not having chest pain at this time. Adenosine is usually not indicated unless the heart rate is greater than 150 beats/min. 42. A patient presents with atrial flutter with an atrial rate of 280 beats/min and a ventricular rate of 70 beats/min. Which of the following best explains this discrepancy in rates? a. The ventricles are too tired to respond to all the atrial signals. b. The AV node does not conduct all the atrial signals to the ventricles. c. Some of the atrial beats are blocked before reaching the AV node. d. The ventricles are responding to a ventricular ectopic pacemaker. ANS: B The atrioventricular (AV) node does not allow conduction of all these impulses to the ventricles. In this case, the rhythm would be described as atrial flutter with a 4:1 AV block, indicating that only one of every four atrial signals is conducted to the ventricles. 43. New-onset atrial fibrillation can be serious for which of the following reasons? a. It increases the risk of stroke and pulmonary embolism from atrial clots. b. It increases the patient's risk of deep venous thrombosis. c. It may increase cardiac output to dangerous levels. d. It indicates that the patient is about to have an MI. ANS: A In atrial fibrillation the atria do not contract normally; they quiver. This increases the chance of the blood clotting in the atria because of a lack of complete emptying of the atria. These clots can break free and cause embolic strokes and pulmonary emboli. Atrial fibrillation does not indicate impending myocardial infarction or an increased risk of deep venous thrombosis. Atrial fibrillation decreases cardiac output from the loss of atrial kick. 44. Which of the following is most often found in ventricular dysrhythmias? a. Retrograde P waves c. No P waves b. Wide QRS complexes d. An inverted T wave ANS: B Ventricular dysrhythmias result from an ectopic focus in any portion of the ventricular myocardium. The usual conduction pathway through the ventricles is not used, and the wave of depolarization must spread from cell to cell. As a result, the QRS complex is prolonged and is always greater than 0.12 second. It is the width of the QRS, not the height, that is important in the diagnosis of ventricular ectopy. 45. The patient has an HR of 84 beats/min and an SV of 65 mL. Calculate the CO. a. 149 mL c. 4650 mL b. 500 mL d. 5460 mL ANS: D Cardiac output (CO) is the product of heart rate (HR) multiplied by stroke volume (SV). SV is the volume of blood ejected by the heart during each beat (reported in milliliters). 84 x 65 = 5460 mL 46. After an MI, a patient presents with an increasing frequency of PVCs. The patient's heart rate is 110 beats/min, and ECG indicates a sinus rhythm with up to five unifocal PVCs per minute. Which of the following should be done? The patient is alert and responsive and denies any chest pain or dyspnea. a. Administer lidocaine 100 mg bolus IV push stat. b. Administer Cardizem 20 mg IV push stat. c. Notify the physician and monitor the patient closely. d. Nothing; PVCs are expected in this patient. ANS: C Although premature ventricular contractions (PVCs) are frequently present after myocardial infarction, they are not always benign. In individuals with underlying heart disease, PVCs or episodes of self-terminating ventricular tachycardia (VT) are potentially malignant. Nonsustained VT is defined as three or more consecutive premature ventricular beats at a rate faster than 110 beats/min lasting less than 30 seconds. The patient does not appear symptomatic from the PVCs at this time; therefore, lidocaine is not indicated. Cardizem is not prescribed for ventricular ectopy. 47. A patient becomes unresponsive. The patient's heart rate is 32 beats/min, idioventricular rhythm; blood pressure is 60/32 mm Hg; SpO2 is 90%; and respiratory rate is 14 breaths/min. Which of the following interventions would the nurse do first? a. Notify the physician and hang no