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CCRN Practice Questions with verified answers- Cardiovascular
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CCRN Practice Questions with verified answers- Cardiovascular
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CCRN Practice Questions with verifiedanswers- Cardiovascular
A patient is in cardiac and respiratory arrest. The selection of medications to reestablish cardiac
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function would stimulate the sympathetic nervous system beta1 receptors. This stimulation
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would result in increased automaticity and which of the
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following?
a. Increased myocardial contractility
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b. Decreased left ventricular stroke work
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c. Decreased myocardial oxygen consumption
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d. Increased left ventricular afterload - ➡ Correct answer: a
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Rationale: The sympathetic nervous system contains alpha, beta, and dopaminergic receptors
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that produce various responses when stimulated. Stimulation of beta1 receptors increases
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heart rate, conductivity, and myocardial contractility. Stimulation of beta2 receptors produces
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vasodilation and bronchodilation. Alpha receptors, when stimulated,
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produce vasoconstriction. Stimulation of dopaminergic receptors produces a vasodilating
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effect on renal, mesenteric, coronary, and cerebral vessels.
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Test-Taking Strategy: Note the helpful clue in the stem: stimulate the sympathetic system and
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recall that this results in a fight-or-flight response—the body is responding to survive. Stroke
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volume would increase, so eliminate option b. Afterload would increase, but this is due to alpha
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stimulation, not beta1 stimulation, so eliminate option d. Because the heart is working faster
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and harder, the myocardial oxygen consumption does increase, so eliminate option c.
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Remember that the primary effects of beta1 receptors are to increase heart rate, contractility,
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and rate of conduction. Choose option a. A memory aid that also may help is this: beta 1 beta 2, 1
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heart 2 lungs: beta1 affects the heart, and beta2 affects the lungs.
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A patient arrived in the emergency department with complaints of chest pain. The 12-lead
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electrocardiogram shows ST segment elevation in leads V3 and V4. Occlusion of the affected
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coronary artery most likely would affect perfusion to which portion of the
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conduction system? t
a. Sinoatrial (SA) node
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,b. Bachmann's bundle
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c. Atrioventricular (AV) node
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d. Bundle of His - ➡ Correct answer: d
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Rationale: ST segment elevation in leads V3 and V4 indicates injury to the anterior wall, which
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would occur with occlusion of the left anterior descending (LAD) artery. In most persons, the SA
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node, Bachmann's bundle, and AV node are supplied by the right coronary artery. The bundle of
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His is supplied by the left anterior descending artery. This is why an
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anterior myocardial infarction may cause type II second-degree AV block or third-degree AV
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heart block at the level of the bundle of His.
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Test-Taking Strategy: Note that options a, b, and c are part of the supraventricular conduction
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system. They usually are supplied by the right coronary artery. The LAD artery supplies most of
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the interventricular conduction system, including the bundle of His and
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the bundle branches.
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Oxygen delivery (DO2) is the product of which of the following?
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a. PaO2, hemoglobin, mean arterial pressure
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b. SaO2, hemoglobin, cardiac output
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c. SvO2, cardiac index, SaO2
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d. PaO2, mean arterial pressure, SvO2 - ➡ Correct answer: b
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Rationale: Ninety-seven percent of oxygen is attached to the hemoglobin molecule, so the SaO2
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(arterial oxygen saturation) is a more accurate reflection of the amount of oxygen in blood. The
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PaO2 represents only the 3% that is dissolved in the plasma. The lungs must put the oxygen in
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the blood, the hemoglobin must carry the oxygen, and the cardiac output is a reflection of how
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well the heart is moving the blood with its hemoglobin with attached
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oxygen. SvO2 (venous oxygen saturation) is a reflection of the oxygen reserve. SvO2 is what is
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left over after the tissues have extracted what they need. The mean arterial pressure is a
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reflection of organ tissue perfusion pressure but does not indicate anything about the amount
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of oxygen in that blood.
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Test-Taking Strategy: Oxygen is delivered from the arterial end, so choose an option that has
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SaO2 instead of SvO2. Also remember that most oxygen is carried on hemoglobin. Look for SaO2
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(not PaO2) and hemoglobin. The only option with both of these is option b.
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, Which of the following types of block are most likely after an anterior wall myocardial infarction
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(MI)?
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a. Sinus block
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b. Second-degree atrioventricular (AV) block, type I
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c. Second-degree AV block, type II
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d. Third-degree AV block with junctional escape rhythm - ➡ Correct answer: c
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Rationale: Anterior MI is caused by a left anterior descending (LAD) artery lesion. The LAD
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artery supplies the bundle of His and bundle branches, so anterior MIs may cause blocks of the
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bundle of His or bundle branches. Second-degree AV block type II is a block at the level of the
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bundle of His. If this patient does develop a third-degree AV block, it would be at the level of the
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bundle of His, and the only escape rhythm available below the bundle of His is a ventricular
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escape rhythm.
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Test-Taking Strategy: The sinus node is supplied by right coronary artery (in 55% of people) or t t t t t t t t t t t t t t t
left coronary artery (in 45% of people), so eliminate option a. Type I AV block, also called
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Wenckebach, is a block at the AV node, and the AV node is supplied by right coronary artery (in
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90% of people) or left coronary artery (10%), so eliminate option b. The
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LAD artery supplies the bundle of His, and blocks in this area would eliminate the possibility of
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junctional escape rhythms, so eliminate option d. Choose option c.
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A patient develops atrial fibrillation after abdominal surgery. Her blood pressure falls from
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110/70 mm Hg to 92/68 mm Hg. The hypotension is related to which of the following?
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a. Decrease in ventricular contractility
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b. Hypovolemia
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c. Mural thrombi
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d. Decrease in ventricular filling - ➡ Correct answer: d
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Rationale: The contribution that atrial contraction makes to ventricular filling volume is
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approximately 15% to 30%. Atrial fibrillation results in quivering but not contracting atria. The
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loss of 15% to 30% of diastolic filling volume reduces cardiac output and can have significant
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hemodynamic consequences. Although mural thrombi also are a problem, they
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result in an embolic phenomenon rather than a direct decrease in cardiac output. The
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relationship between the development of atrial fibrillation and the decrease in cardiac output
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make hypovolemia and decrease in contractility less likely.
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