CCT - Practice Test
1. Which heart chamber functions to pump deoxygenated blood to the lungs?
a. Right atrium
b. Right ventricle
c. Left atrium
d. Left ventricle - CORRECT ANSWER-1. B: The right ventricle pumps the
deoxygenated blood it has received from the right atrium to the lungs. The
right atrium pumps deoxygenated blood from the body to the right ventricle.
The left atrium pumps oxygenated blood from the lungs to the left ventricle.
The left ventricle pumps oxygenated blood to the body.
2. Which lead is the most affected by respiration?
a. V2
b. V4
c. Lead III
d. Lead I - CORRECT ANSWER-2. C: Lead III is the most affected by
respiration, and therefore the waveforms may look different depending on the
respiratory cycle. Because of this, a Q wave that only appears in lead III and is
not associated with other corresponding changes in other leads is not
significant.
3. Which of the following is the correct sequence by which action potentials
are conducted through the heart?"
a. SA node → AV node → bundle branches → Purkinje fibers
b. Bundle branches → Purkinje fibers → SA node → AV node
c. Purkinje fibers → SA node → bundle branches → AV node
d. AV node → SA node → bundle branches → Purkinje fibers - CORRECT
ANSWER-3. A: The sequence by which an action potential is conducted
through the heart is from the sinoatrial (SA) node to the atrioventricular (AV)
node to the bundle branches and then to the Purkinje fibers.
4. What type of heart block is seen in the following electrocardiogram (ECG)
strip?"
a. First-degree heart block
b. Second-degree heart block, type 1
c. Second-degree heart block, type 2
d. Third-degree heart block - CORRECT ANSWER-4. B: The pictured ECG is
a second-degree heart block, type 1. This rhythm is also called Mobitz I or
,Wenckebach. With this heart block the PR interval gets longer with each beat
until eventually a P wave occurs, but a QRS does not follow (a beat is
skipped). After the skipped beat, the pattern starts over again. A first-degree
heart block occurs when the PR interval is longer than 0.2 seconds, but the
PR interval generally remains constant and the QRS is not dropped. A
second-degree heart block, type 2, also called Mobitz II, is apparent when the
QRS suddenly fails to show up after a P wave. A fairly consistent ratio of P
waves to QRS complexes is common, and this rhythm lacks the increasing PR
interval that is seen in the Mobitz I block. A third-degree heart block is also
called a complete heart block and the atria and ventricles beat independently
of one another.
5. When calibrating an ECG machine, what is the standard size of the
calibration mark representing the sensitivity of the ECG machine?
a. 5 mm in height
b. 10 mm in height
c. 15 mm in height
d. 20 mm in height - CORRECT ANSWER-5. B: The calibration mark
representing the sensitivity of the ECG should be 10 mm in height (two large
squares). This mark is usually found on the left side of the page at the
beginning of each line of the ECG. When this is set correctly it means that for
every millivolt measured from the patient, a deflection of 10 mm will be
recorded on the trace.
6. Which of the following is the mechanism of action of nitrates?
a. Decrease the responsiveness of heart to the sympathetic nervous system
b. Lower the heart rate
c. Decrease cardiac contractility
d. Dilation of coronary arteries - CORRECT ANSWER-6. D: Nitrates are useful
for the prevention and treatment of angina. They work by dilating the coronary
arteries and thus increasing the blood flow to the heart. They dilate peripheral
veins, and, in higher doses, other peripheral arteries, which decreases preload
and afterload. Beta-blockers decrease the responsiveness of the heart to the
sympathetic nervous system. Calcium channel blockers, beta-blockers, and
other medications decrease cardiac contractility and decrease heart rate.
7. Which phase of the action potential in fast response myocardial tissues
consists of rapid depolarization, with the resting cell being brought to
threshold?
, a. Phase 0
b. Phase 1
c. Phase 2
d. Phase 3 - CORRECT ANSWER-7. A: Phase 0 consists of rapid
depolarization of the cell to threshold, which leads to activation of
voltage-dependent sodium channels. Phase 1 consists of a slight "notch" of
repolarization caused mainly by the activation of transient potassium currents
(potassium leaving the cell) and a corresponding rapid decrease in the sodium
current. Phase 2 is a plateau phase during which "late" calcium, and to a
lesser extent sodium, currents offset the effect of potassium currents and
temporarily stabilize the membrane potential. Phase 3 refers to repolarization
and return to resting potential due to increased potassium currents. Phase 4 is
the resting membrane potential.
8. The depolarizing current in pacemaker cells is created primarily by which of
the following ions?
a. Sodium
b. Calcium
c. Potassium
d. Chloride - CORRECT ANSWER-8. B: The depolarizing current in cardiac
pacemaker cells is carried primarily by relatively slow, inward calcium
currents. In most other depolarizing cells, such as muscle cells, the
depolarization is created by fast sodium currents. Potassium plays a role in
repolarization of the cells.
9. Which of the following commonly limits the diagnostic value of Holter
monitoring?
a. Patient noncompliance with keeping track of events
b. Lack of continuous monitoring
c. Small capacity of recording devices
d. Transmission of data depends on patient participation - CORRECT
ANSWER-9. A: Patient noncompliance with keeping a diary of their symptoms
and using event markers significantly limits the diagnostic value of Holter
monitoring. It is important for patients to record and mark their symptoms in
order to correlate events with the data collected. Holter monitoring is a type of
continuous monitoring and benefits include the large capacity of the recording
devices as well as the ability to transmit data without patient participation.
10. Which of the following effects is caused by the actions of the
parasympathetic nervous system on the heart?
1. Which heart chamber functions to pump deoxygenated blood to the lungs?
a. Right atrium
b. Right ventricle
c. Left atrium
d. Left ventricle - CORRECT ANSWER-1. B: The right ventricle pumps the
deoxygenated blood it has received from the right atrium to the lungs. The
right atrium pumps deoxygenated blood from the body to the right ventricle.
The left atrium pumps oxygenated blood from the lungs to the left ventricle.
The left ventricle pumps oxygenated blood to the body.
2. Which lead is the most affected by respiration?
a. V2
b. V4
c. Lead III
d. Lead I - CORRECT ANSWER-2. C: Lead III is the most affected by
respiration, and therefore the waveforms may look different depending on the
respiratory cycle. Because of this, a Q wave that only appears in lead III and is
not associated with other corresponding changes in other leads is not
significant.
3. Which of the following is the correct sequence by which action potentials
are conducted through the heart?"
a. SA node → AV node → bundle branches → Purkinje fibers
b. Bundle branches → Purkinje fibers → SA node → AV node
c. Purkinje fibers → SA node → bundle branches → AV node
d. AV node → SA node → bundle branches → Purkinje fibers - CORRECT
ANSWER-3. A: The sequence by which an action potential is conducted
through the heart is from the sinoatrial (SA) node to the atrioventricular (AV)
node to the bundle branches and then to the Purkinje fibers.
4. What type of heart block is seen in the following electrocardiogram (ECG)
strip?"
a. First-degree heart block
b. Second-degree heart block, type 1
c. Second-degree heart block, type 2
d. Third-degree heart block - CORRECT ANSWER-4. B: The pictured ECG is
a second-degree heart block, type 1. This rhythm is also called Mobitz I or
,Wenckebach. With this heart block the PR interval gets longer with each beat
until eventually a P wave occurs, but a QRS does not follow (a beat is
skipped). After the skipped beat, the pattern starts over again. A first-degree
heart block occurs when the PR interval is longer than 0.2 seconds, but the
PR interval generally remains constant and the QRS is not dropped. A
second-degree heart block, type 2, also called Mobitz II, is apparent when the
QRS suddenly fails to show up after a P wave. A fairly consistent ratio of P
waves to QRS complexes is common, and this rhythm lacks the increasing PR
interval that is seen in the Mobitz I block. A third-degree heart block is also
called a complete heart block and the atria and ventricles beat independently
of one another.
5. When calibrating an ECG machine, what is the standard size of the
calibration mark representing the sensitivity of the ECG machine?
a. 5 mm in height
b. 10 mm in height
c. 15 mm in height
d. 20 mm in height - CORRECT ANSWER-5. B: The calibration mark
representing the sensitivity of the ECG should be 10 mm in height (two large
squares). This mark is usually found on the left side of the page at the
beginning of each line of the ECG. When this is set correctly it means that for
every millivolt measured from the patient, a deflection of 10 mm will be
recorded on the trace.
6. Which of the following is the mechanism of action of nitrates?
a. Decrease the responsiveness of heart to the sympathetic nervous system
b. Lower the heart rate
c. Decrease cardiac contractility
d. Dilation of coronary arteries - CORRECT ANSWER-6. D: Nitrates are useful
for the prevention and treatment of angina. They work by dilating the coronary
arteries and thus increasing the blood flow to the heart. They dilate peripheral
veins, and, in higher doses, other peripheral arteries, which decreases preload
and afterload. Beta-blockers decrease the responsiveness of the heart to the
sympathetic nervous system. Calcium channel blockers, beta-blockers, and
other medications decrease cardiac contractility and decrease heart rate.
7. Which phase of the action potential in fast response myocardial tissues
consists of rapid depolarization, with the resting cell being brought to
threshold?
, a. Phase 0
b. Phase 1
c. Phase 2
d. Phase 3 - CORRECT ANSWER-7. A: Phase 0 consists of rapid
depolarization of the cell to threshold, which leads to activation of
voltage-dependent sodium channels. Phase 1 consists of a slight "notch" of
repolarization caused mainly by the activation of transient potassium currents
(potassium leaving the cell) and a corresponding rapid decrease in the sodium
current. Phase 2 is a plateau phase during which "late" calcium, and to a
lesser extent sodium, currents offset the effect of potassium currents and
temporarily stabilize the membrane potential. Phase 3 refers to repolarization
and return to resting potential due to increased potassium currents. Phase 4 is
the resting membrane potential.
8. The depolarizing current in pacemaker cells is created primarily by which of
the following ions?
a. Sodium
b. Calcium
c. Potassium
d. Chloride - CORRECT ANSWER-8. B: The depolarizing current in cardiac
pacemaker cells is carried primarily by relatively slow, inward calcium
currents. In most other depolarizing cells, such as muscle cells, the
depolarization is created by fast sodium currents. Potassium plays a role in
repolarization of the cells.
9. Which of the following commonly limits the diagnostic value of Holter
monitoring?
a. Patient noncompliance with keeping track of events
b. Lack of continuous monitoring
c. Small capacity of recording devices
d. Transmission of data depends on patient participation - CORRECT
ANSWER-9. A: Patient noncompliance with keeping a diary of their symptoms
and using event markers significantly limits the diagnostic value of Holter
monitoring. It is important for patients to record and mark their symptoms in
order to correlate events with the data collected. Holter monitoring is a type of
continuous monitoring and benefits include the large capacity of the recording
devices as well as the ability to transmit data without patient participation.
10. Which of the following effects is caused by the actions of the
parasympathetic nervous system on the heart?
