Chapter 21 - Cardiovascular Function Flashcards
A nurse is describing the process by which blood is ejected into circulation as the chambers of the heart become smaller. The instructor categorizes this as what action? A. Systole B. Diastole C. Repolarization D. Ejection fraction
A. Systole
Rationale: Systole is the action of the chambers of the heart becoming smaller and ejecting blood. This action of the heart is not diastole (relaxation), ejection fraction (the amount of blood expelled), or repolarization (electrical charging).
During a shift assessment, the nurse is identifying the client’s point of maximum impulse (PMI). Where should the nurse BEST palpate the PMI?
A. Left midclavicular line of the chest at the level of the nipple
B. Left midclavicular line of the chest at the fifth intercostal space
C. Midline between the xiphoid process and the left nipple
D. Two to three centimeters to the left of the sternum
B. Left midclavicular line of the chest at the fifth intercostal space
Rationale: The left ventricle is responsible for the apical beat or the point of maximum impulse, which is normally palpated in the left midclavicular line of the chest wall at the fifth intercostal space.
The nurse is calculating a cardiac client's pulse pressure. If the client's blood pressure is 122/76 mm Hg, what is the client's pulse pressure? A. 46 mm Hg B. 99 mm Hg C. 198 mm Hg D. 76 mm Hg
A. 46 mm Hg
Rationale: Pulse pressure is the difference between the systolic and diastolic pressure. In this case, this value is 46 mm Hg
A client has been admitted to the intensive care unit (ICU) after an ischemic stroke, and a central venous pressure (CVP) monitoring line was placed. The nurse notes a low CVP. Which condition is the MOST likely reason for a low CVP? A. Hypovolemia B. Myocardial infarction (MI) C. Left-sided heart failure D. Aortic valve regurgitation
A. Hypovolemia
Rationale: CVP is a measurement of the pressure in the vena cava or right atrium. A low CVP indicates a reduced right ventricular preload, most often from hypovolemia. An MI is an unlikely cause of low CVP. CVP measures the right side of the heart, so left-sided failure is unlikely to affect CVP. Aortic valve regurgitation is a less likely cause of low CVP.
While auscultating a client’s heart sounds, the nurse hears an extra heart sound immediately after the second heart sound (S2). An audible S3 would be considered an expected finding in which client?
A. A 47-year-old client
B. A 20-year-old client
C. A client who has undergone valve replacement
D. A client who takes a beta-adrenergic blocker
B. A 20-year-old client
Rationale: S3 represents a normal finding in children and adults up to 35 or 40 years of age. In these cases, it is called a physiologic S3. It is an abnormal finding in a client with an artificial valve, an adult older than 40 years of age, or a client who takes a beta blocker.
The physical therapist notifies the nurse that a client with coronary artery disease (CAD) experienced a significant increase in heart rate during physical therapy. The nurse recognizes that an increase in heart rate in a client with CAD may result in which outcome?
A. Development of an atrial–septal defect
B. Myocardial ischemia
C. Formation of a pulmonary embolism
D. Release of potassium ions from cardiac cells
B. Myocardial ischemia
Rationale: Unlike other arteries, the coronary arteries are perfused during diastole. An increase in heart rate shortens diastole and can decrease myocardial perfusion. Clients, particularly those with CAD, can develop myocardial ischemia. An increase in heart rate will not usually result in a pulmonary embolism or create electrolyte imbalances. Atrial-septal defects are congenital.
The nurse is caring for a client who has a history of heart disease. What factor should the nurse identify as possibly contributing to a decrease in cardiac output?
A. A change in position from standing to sitting
B. A heart rate of 54 bpm
C. A pulse oximetry reading of 94%
D. An increase in preload related to ambulation
B. A heart rate of 54 bpm
Rationale: Cardiac output is computed by multiplying the stroke volume by the heart rate. Cardiac output can be affected by changes in either stroke volume or heart rate, such as a rate of 54 bpm. An increase in preload will lead to an increase in stroke volume. A pulse oximetry reading of 94% does not indicate hypoxemia, as hypoxia can decrease contractility. Transitioning from standing to sitting would more likely increase rather than decrease cardiac output.
A client is admitted to a cardiac unit with the diagnosis of syncope. Orthostatic blood pressures are ordered every 8 hours. Which blood pressure readings would BEST indicate that the nurse should notify the health care provider of a positive finding?
A. Supine 146/70 mm Hg, sitting 132/68 mm Hg, standing 130/66 mm Hg
B. Supine 110/62 mm Hg, sitting 108/58 mm Hg, standing 106/56 mm Hg
C. Supine 128/72 mm Hg, sitting 118/70 mm Hg, standing 110/66 mm Hg
D. Supine 138/76 mm Hg, sitting 132/66 mm Hg, standing 122/52 mm Hg
D. Supine 138/76 mm Hg, sitting 132/66 mm Hg, standing 122/52 mm Hg
Rationale: Postural (orthostatic) hypotension is a significant drop in blood pressure (20 mm Hg systolic or more or 10 mm Hg diastolic or more) within 3 minutes of moving from a lying or sitting to a standing position to indicate a positive result.
The critical care nurse is caring for a client with a central venous pressure (CVP) monitoring system. The nurse notes that the client’s CVP is increasing. This may indicate:
A. psychosocial stress.
B. hypervolemia.
C. dislodgment of the catheter.
D. hypomagnesemia.
B. hypervolemia.
Rationale: CVP is a useful hemodynamic parameter to observe when managing an unstable client’s fluid volume status. An increasing pressure may be caused by hypervolemia or by a condition, such as heart failure, that results in decreased myocardial contractility. Stress, dislodgment of the catheter, and low magnesium levels would not typically result in increased CVP.
The critical care nurse is caring for a client with a pulmonary artery pressure monitoring system. In addition to assessing left ventricular function, what is an additional function of a pulmonary artery pressure monitoring system?
A. To assess the client’s response to fluid and drug administration
B. To obtain specimens for arterial blood gas measurements
C. To dislodge pulmonary emboli
D. To diagnose the etiology of chronic obstructive pulmonary disease
A. To assess the client’s response to fluid and drug administration
Rationale: Pulmonary artery pressure monitoring is an important tool used in critical care for assessing left ventricular function (cardiac output), diagnosing the etiology of shock, and evaluating the client’s response to medical interventions, such as fluid administration and vasoactive medications. Pulmonary artery monitoring is preferred over central venous pressure monitoring for the client with heart failure. Arterial catheters are useful when arterial blood gas measurements and blood samples need to be obtained frequently. Neither intervention is used to clear pulmonary emboli.
The cardiac care nurse is reviewing the conduction system of the heart. The nurse is aware that electrical conduction of the heart usually originates in the sinoatrial (SA) node and then proceeds in which sequence?
A. Bundle of His to atrioventricular (AV) node to Purkinje fibers
B. AV node to Purkinje fibers to bundle of His
C. Bundle of His to Purkinje fibers to AV node
D. AV node to bundle of His to Purkinje fibers
D. AV node to bundle of His to Purkinje fibers
Rationale: The normal electrophysiological conduction route is SA node to AV node to bundle of His to Purkinje fibers.
A client has had a myocardial infarction and has been diagnosed as having damage to the layer of the heart responsible for the pumping action. This client experienced damage to which area of the heart? A. Endocardium B. Pericardium C. Myocardium D. Visceral pericardium
C. Myocardium
Rationale: The middle layer of the heart, or myocardium, is made up of muscle fibers and is responsible for the pumping action. The inner layer, or endocardium, consists of endothelial tissue and lines the inside of the heart and valves. The heart is encased in a thin, fibrous sac called the pericardium, which is composed of two layers. Adhering to the epicardium is the visceral pericardium. Enveloping the visceral pericardium is the parietal pericardium, a tough fibrous tissue that attaches to the great vessels, diaphragm, sternum, and vertebral column and supports the heart in the mediastinum
The nurse working on a cardiac care unit is caring for a client whose stroke volume has increased. The nurse is aware that afterload influences a client's stroke volume. The nurse recognizes that which factor increases afterload? A. Arterial vasoconstriction B. Venous vasoconstriction C. Arterial vasodilation D. Venous vasodilation
A. Arterial vasoconstriction
Rationale: Afterload, or resistance to ejection of blood from the ventricle, is one determinant of stroke volume. There is an inverse relationship between afterload and stroke volume. Arterial vasoconstriction increases afterload, which leads to decreased stroke volume. Conversely, arterial vasodilation decreases afterload because there is less resistance to ejection, and stroke volume increases. Preload, or the degree of stretch of the ventricular cardiac muscle fibers at the end of diastole, is another determinant of stroke volume. There is a direct relationship between preload and stroke volume. Venous vasoconstriction increases preload, which leads to increased stroke volume. Conversely, venous vasodilation decreases preload, which leads to decreased stroke volume. Because the ventricles only eject blood into arteries, not veins, afterload is only affected by arterial, not venous, vasoconstriction and vasodilation. Because the ventricles only receive blood from veins, not arteries, preload is only affected by venous, not arterial, vasoconstriction and vasodilation.
A nurse is preparing a client for scheduled transesophageal echocardiography. Which action should the nurse perform?
A. Instruct the client to drink 1 L of water before the test.
B. Administer intravenous (IV) benzodiazepines and opioids.
C. Inform the client that the client will remain on bed rest following the procedure.
D. Inform the client that an access line will be initiated in the femoral artery
C. Inform the client that the client will remain on bed rest following the procedure.
Rationale: During the recovery period, the client must maintain bed rest with the head of the bed elevated to 45 degrees. The client must be NPO 6 hours pre-procedure. The client is sedated to make the client comfortable, but the client will not be heavily sedated and opioids are not necessary. Also, the client will have a peripheral IV line initiated pre-procedure.
The nurse is caring for a client admitted with angina who is scheduled for cardiac catheterization. The client is anxious and asks the reason for this test. The nurse should explain that cardiac catheterization is most commonly done for which purpose?
A. To assess how blocked or open a client’s coronary arteries are
B. To detect how efficiently a client’s heart muscle contracts
C. To evaluate cardiovascular response to stress
D. To evaluate cardiac electrical activity
A. To assess how blocked or open a client’s coronary arteries are
Rationale: Cardiac catheterization is usually used to assess coronary artery patency to determine whether revascularization procedures are necessary. A thallium stress test shows myocardial ischemia after stress. An ECG shows the electrical activity of the heart.
