CCRN - CARDIOVASCULAR PRACTICE
QUESTIONS WITH 100% CORRECTLY
SOLVED ANSWERS AND DETAILED
RATIONALES
A patient is in cardiac and respiratory arrest. The selection of
medications to reestablish cardiac function would stimulate the
sympathetic nervous system beta1 receptors. This stimulation would
result in increased automaticity and which of the
following?
a. Increased myocardial contractility
b. Decreased left ventricular stroke work
c. Decreased myocardial oxygen consumption
d. Increased left ventricular afterload -- Correct Answer ✔✔ Correct
answer: a
Rationale: The sympathetic nervous system contains alpha, beta, and
dopaminergic receptors that produce various responses when
stimulated. Stimulation of beta1 receptors increases heart rate,
conductivity, and myocardial contractility. Stimulation of beta2
receptors produces vasodilation and bronchodilation. Alpha receptors,
when stimulated,
produce vasoconstriction. Stimulation of dopaminergic receptors
produces a vasodilating
effect on renal, mesenteric, coronary, and cerebral vessels.
Test-Taking Strategy: Note the helpful clue in the stem: stimulate the
sympathetic system and recall that this results in a fight-or-flight
response—the body is responding to survive. Stroke volume would
increase, so eliminate option b. Afterload would increase, but this is
due to alpha stimulation, not beta1 stimulation, so eliminate option d.
Because the heart is working faster and harder, the myocardial oxygen
,consumption does increase, so eliminate option c. Remember that the
primary effects of beta1 receptors are to increase heart rate,
contractility, and rate of conduction. Choose option a. A memory aid
that also may help is this: beta 1 beta 2, 1 heart 2 lungs: beta1 affects
the heart, and beta2 affects the lungs.
A patient arrived in the emergency department with complaints of
chest pain. The 12-lead electrocardiogram shows ST segment elevation
in leads V3 and V4. Occlusion of the affected coronary artery most
likely would affect perfusion to which portion of the
conduction system?
a. Sinoatrial (SA) node
b. Bachmann's bundle
c. Atrioventricular (AV) node
d. Bundle of His -- Correct Answer ✔✔ Correct answer: d
Rationale: ST segment elevation in leads V3 and V4 indicates injury to
the anterior wall, which would occur with occlusion of the left anterior
descending (LAD) artery. In most persons, the SA node, Bachmann's
bundle, and AV node are supplied by the right coronary artery. The
bundle of His is supplied by the left anterior descending artery. This is
why an
anterior myocardial infarction may cause type II second-degree AV
block or third-degree AV heart block at the level of the bundle of His.
Test-Taking Strategy: Note that options a, b, and c are part of the
supraventricular conduction system. They usually are supplied by the
right coronary artery. The LAD artery supplies most of the
interventricular conduction system, including the bundle of His and
the bundle branches.
Oxygen delivery (DO2) is the product of which of the following?
a. PaO2, hemoglobin, mean arterial pressure
b. SaO2, hemoglobin, cardiac output
c. SvO2, cardiac index, SaO2
d. PaO2, mean arterial pressure, SvO2 -- Correct Answer ✔✔ Correct
answer: b
Rationale: Ninety-seven percent of oxygen is attached to the
hemoglobin molecule, so the SaO2 (arterial oxygen saturation) is a
, more accurate reflection of the amount of oxygen in blood. The PaO2
represents only the 3% that is dissolved in the plasma. The lungs must
put the oxygen in the blood, the hemoglobin must carry the oxygen,
and the cardiac output is a reflection of how well the heart is moving
the blood with its hemoglobin with attached
oxygen. SvO2 (venous oxygen saturation) is a reflection of the oxygen
reserve. SvO2 is what is left over after the tissues have extracted what
they need. The mean arterial pressure is a reflection of organ tissue
perfusion pressure but does not indicate anything about the amount of
oxygen in that blood.
Test-Taking Strategy: Oxygen is delivered from the arterial end, so
choose an option that has SaO2 instead of SvO2. Also remember that
most oxygen is carried on hemoglobin. Look for SaO2 (not PaO2) and
hemoglobin. The only option with both of these is option b.
Which of the following types of block are most likely after an anterior
wall myocardial infarction (MI)?
a. Sinus block
b. Second-degree atrioventricular (AV) block, type I
c. Second-degree AV block, type II
d. Third-degree AV block with junctional escape rhythm -- Correct
Answer ✔✔ Correct answer: c
Rationale: Anterior MI is caused by a left anterior descending (LAD)
artery lesion. The LAD artery supplies the bundle of His and bundle
branches, so anterior MIs may cause blocks of the bundle of His or
bundle branches. Second-degree AV block type II is a block at the level
of the bundle of His. If this patient does develop a third-degree AV
block, it would be at the level of the bundle of His, and the only escape
rhythm available below the bundle of His is a ventricular escape
rhythm.
Test-Taking Strategy: The sinus node is supplied by right coronary
artery (in 55% of people) or left coronary artery (in 45% of people), so
eliminate option a. Type I AV block, also called Wenckebach, is a block
at the AV node, and the AV node is supplied by right coronary artery
(in 90% of people) or left coronary artery (10%), so eliminate option b.
The
QUESTIONS WITH 100% CORRECTLY
SOLVED ANSWERS AND DETAILED
RATIONALES
A patient is in cardiac and respiratory arrest. The selection of
medications to reestablish cardiac function would stimulate the
sympathetic nervous system beta1 receptors. This stimulation would
result in increased automaticity and which of the
following?
a. Increased myocardial contractility
b. Decreased left ventricular stroke work
c. Decreased myocardial oxygen consumption
d. Increased left ventricular afterload -- Correct Answer ✔✔ Correct
answer: a
Rationale: The sympathetic nervous system contains alpha, beta, and
dopaminergic receptors that produce various responses when
stimulated. Stimulation of beta1 receptors increases heart rate,
conductivity, and myocardial contractility. Stimulation of beta2
receptors produces vasodilation and bronchodilation. Alpha receptors,
when stimulated,
produce vasoconstriction. Stimulation of dopaminergic receptors
produces a vasodilating
effect on renal, mesenteric, coronary, and cerebral vessels.
Test-Taking Strategy: Note the helpful clue in the stem: stimulate the
sympathetic system and recall that this results in a fight-or-flight
response—the body is responding to survive. Stroke volume would
increase, so eliminate option b. Afterload would increase, but this is
due to alpha stimulation, not beta1 stimulation, so eliminate option d.
Because the heart is working faster and harder, the myocardial oxygen
,consumption does increase, so eliminate option c. Remember that the
primary effects of beta1 receptors are to increase heart rate,
contractility, and rate of conduction. Choose option a. A memory aid
that also may help is this: beta 1 beta 2, 1 heart 2 lungs: beta1 affects
the heart, and beta2 affects the lungs.
A patient arrived in the emergency department with complaints of
chest pain. The 12-lead electrocardiogram shows ST segment elevation
in leads V3 and V4. Occlusion of the affected coronary artery most
likely would affect perfusion to which portion of the
conduction system?
a. Sinoatrial (SA) node
b. Bachmann's bundle
c. Atrioventricular (AV) node
d. Bundle of His -- Correct Answer ✔✔ Correct answer: d
Rationale: ST segment elevation in leads V3 and V4 indicates injury to
the anterior wall, which would occur with occlusion of the left anterior
descending (LAD) artery. In most persons, the SA node, Bachmann's
bundle, and AV node are supplied by the right coronary artery. The
bundle of His is supplied by the left anterior descending artery. This is
why an
anterior myocardial infarction may cause type II second-degree AV
block or third-degree AV heart block at the level of the bundle of His.
Test-Taking Strategy: Note that options a, b, and c are part of the
supraventricular conduction system. They usually are supplied by the
right coronary artery. The LAD artery supplies most of the
interventricular conduction system, including the bundle of His and
the bundle branches.
Oxygen delivery (DO2) is the product of which of the following?
a. PaO2, hemoglobin, mean arterial pressure
b. SaO2, hemoglobin, cardiac output
c. SvO2, cardiac index, SaO2
d. PaO2, mean arterial pressure, SvO2 -- Correct Answer ✔✔ Correct
answer: b
Rationale: Ninety-seven percent of oxygen is attached to the
hemoglobin molecule, so the SaO2 (arterial oxygen saturation) is a
, more accurate reflection of the amount of oxygen in blood. The PaO2
represents only the 3% that is dissolved in the plasma. The lungs must
put the oxygen in the blood, the hemoglobin must carry the oxygen,
and the cardiac output is a reflection of how well the heart is moving
the blood with its hemoglobin with attached
oxygen. SvO2 (venous oxygen saturation) is a reflection of the oxygen
reserve. SvO2 is what is left over after the tissues have extracted what
they need. The mean arterial pressure is a reflection of organ tissue
perfusion pressure but does not indicate anything about the amount of
oxygen in that blood.
Test-Taking Strategy: Oxygen is delivered from the arterial end, so
choose an option that has SaO2 instead of SvO2. Also remember that
most oxygen is carried on hemoglobin. Look for SaO2 (not PaO2) and
hemoglobin. The only option with both of these is option b.
Which of the following types of block are most likely after an anterior
wall myocardial infarction (MI)?
a. Sinus block
b. Second-degree atrioventricular (AV) block, type I
c. Second-degree AV block, type II
d. Third-degree AV block with junctional escape rhythm -- Correct
Answer ✔✔ Correct answer: c
Rationale: Anterior MI is caused by a left anterior descending (LAD)
artery lesion. The LAD artery supplies the bundle of His and bundle
branches, so anterior MIs may cause blocks of the bundle of His or
bundle branches. Second-degree AV block type II is a block at the level
of the bundle of His. If this patient does develop a third-degree AV
block, it would be at the level of the bundle of His, and the only escape
rhythm available below the bundle of His is a ventricular escape
rhythm.
Test-Taking Strategy: The sinus node is supplied by right coronary
artery (in 55% of people) or left coronary artery (in 45% of people), so
eliminate option a. Type I AV block, also called Wenckebach, is a block
at the AV node, and the AV node is supplied by right coronary artery
(in 90% of people) or left coronary artery (10%), so eliminate option b.
The
