Question 1

Afterload is influenced by arterial blood pressure, arterial distensibility, and arterial resistance.

Accepted Answer

Afterload is the pressure or resistance against which the ventricles must pump to eject blood. Afterload is influenced by arterial blood pressure, arterial distensibility (ability to become stretched), and arterial resistance. The less the resistance (lower afterload), the more easily blood can be ejected. Increased afterload (increased resistance) results in increased cardiac workload.

Question 2

Each ventricle holds about 300 mL of blood when it is full. They normally eject about three fourths of this volume with each contraction.

Accepted Answer

Each ventricle holds about 150 mL of blood when it is full. They normally eject about half this volume (70 to 80 mL) with each contraction. The percentage of blood pumped out of a heart chamber with each contraction is called the ejection fraction. Ejection fraction is used as a measure of ventricular function. A normal ejection fraction is between 50% and 65%.

Question 3

The two most common sites of atrioventricular (AV) block are the:

Accepted Answer

AV block can occur at the level of the AV node, at the level of the bundle branches, or at some site in between, such as the bundle of His. The two most common sites of AV block are the AV node (nodal block) and the bundle branches (infranodal block).

Question 4

The difference between second-degree type I and type II AV block is that with:

Accepted Answer

In second-degree AV block type I, the PR interval becomes progressively longer until a P wave appears without a QRS complex. In second-degree AV block type II, the PR interval is constant before each conducted QRS complex.

Question 5

A heart rate that is too fast may be associated with:

Accepted Answer

A heart rate that is too fast may be associated with sinus tachycardia, atrial flutter or atrial fibrillation with a rapid ventricular response, supraventricular tachycardias, or ventricular tachycardia.

Question 6

In a third-degree AV block:

Accepted Answer

In third-degree AV block, impulses generated by the SA node are blocked before reaching the ventricles so no P waves are conducted and consequently there is no PR interval. The atria and ventricles beat independently of each other. Thus, third-degree AV block is also called complete AV block.

Question 7

Which of the following types of second-degree AV block is most likely to rapidly progress rapidly to a third-degree AV block without warning?

Accepted Answer

Second-degree AV block type II occurs below the AV node, either at the bundle of His or, more commonly, at the level of the bundle branches. This type of block is more serious than second-degree AV block type I and may rapidly progress to third-degree AV block without warning. Preparations should be made for pacing when this rhythm is recognized. The use of atropine should be avoided. In this situation, atropine will usually not improve the block but will increase the rate of discharge of the SA node. This may trigger a situation in which even fewer impulses are conducted through to the ventricles and the ventricular rate is further slowed.

Question 8

Preload is:

Accepted Answer

Preload is the force exerted on the walls of the ventricles at the end of diastole. The volume of blood returning to the heart influences preload. More blood returning to the right atrium increases preload; less blood returning decreases preload.

Question 9

Absolute hypovolemia is a term used to describe:

Accepted Answer

Hypotension may be caused by volume deficit or a vascular resistance problem. Absolute hypovolemia is a term used to describe an actual fluid deficit. In contrast, relative hypovolemia is a term used to describe a change in tank size due to vasodilation from any cause or redistribution of body fluid to third spaces.

Question 10

A third-degree AV block associated with an anterior MI is usually preceded by:

Accepted Answer

Third-degree AV block associated with an inferior MI is thought to be the result of a block above the bundle of His. It often occurs after progression from first-degree AV block or second-degree AV block type I. The resulting rhythm is usually stable because the escape pacemaker is usually junctional (narrow QRS complexes) with a ventricular rate of more than 40 beats/min.Third-degree AV block associated with an anterior MI is usually preceded by second-degree AV block type II or an intraventricular conduction delay (right or left bundle branch block). The resulting rhythm is usually unstable because the escape pacemaker is usually ventricular (wide QRS complexes) with a ventricular rate of less than 40 beats/min.

Question 11

As the left ventricle fails,

Accepted Answer

As the left ventricle fails, blood builds up in the lungs because the left ventricle is unable to eject all the blood within its walls. Right ventricular failure is often a result of left ventricular failure. Blood backs up behind the right ventricle, increasing the pressure in the right atrium. If the right atrium is unable to eject the blood within its walls, blood backs up into the superior and inferior venae cavae. Veins become congested with blood because the superior and inferior venae cavae cannot drain into an already full right atrium. Because venous return is delayed, organs become congested with blood. As venous congestion worsens, increased pressure within the veins forces serous fluid through capillary walls and into body tissues, producing edema.

Question 12

When AV block is associated with an inferior wall infarction and produces a narrow QRS complex, the block is probably located in the:

Accepted Answer

When AV block is associated with an inferior wall infarction and produces a narrow QRS complex, it is probably located in the AV node. However, when anterior wall infarction produces AV block it usually occurs in the bundle branches (infranodal) and displays a wide QRS complex.

Question 13

Cardiac output is determined by:

Accepted Answer

Cardiac output is the amount of blood pumped into the aorta each minute by the heart. It is defined as the stroke volume (amount of blood ejected from a ventricle with each heartbeat) multiplied by the heart rate. Cardiac output may be affected by an increase or decrease in heart rate or stroke volume.

Question 14

Possible causes of relative hypovolemia include:

Accepted Answer

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Question 15

When AV block is associated with an anterior wall infarction and produces a wide QRS complex, the block is probably located in the:

Accepted Answer

When anterior wall infarction produces AV block it usually occurs in the bundle branches (infranodal) and displays a wide QRS complex.

Question 16

Which of the following statements is INCORRECT regarding a first-degree AV block?

Accepted Answer

First-degree AV block may be a normal finding in individuals with no history of cardiac disease, especially in athletes. First-degree AV block may also occur because of ischemia or injury to the AV node or junction, medication therapy (such as quinidine, procainamide, beta-blockers, calcium channel blockers, digitalis, and amiodarone), rheumatic heart disease, hyperkalemia, acute MI (often an inferior wall MI), or increased vagal tone. The patient with a first-degree AV block is often asymptomatic; however, marked first-degree AV block can lead to symptoms even in the absence of higher degrees of AV block. First-degree AV block that occurs with acute MI should be monitored closely.

Question 17

List four complications associated with MI.

Accepted Answer

The answer of List four complications associated with MI....

Question 18

List the cardiovascular system components necessary to ensure normal body tissue perfusion.

Accepted Answer

The answer of List the cardiovascular system components necessary to...

Question 19

Define cardiogenic shock.

Accepted Answer

The answer of Define cardiogenic shock....

Quiz 6: Evidence-Based Practice