CCT - Practice Test Questions with Verified Solutions

CCT - Practice Test Questions with Verified Solutions 1. Which heart chamber functions to pump deoxygenated blood to the lungs? a. Right atrium b. Right ventricle c. Left atrium d. Left ventricle 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 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 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 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 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 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 7. A: Phase 0