Question 1

An echocardiogram reveals an ejection fraction of 55%.On the basis of this information,how would the patient's cardiac function be described?

Accepted Answer

Ejection fraction is expressed as a percent,with normal being at least greater than 50%.An ejection fraction of less than 35% indicates poor ventricular function (as in cardiomyopathy),poor ventricular filling,obstruction to outflow (as in some valve stenosis conditions),or a combination of these.

Question 2

A patient reports feeling dizzy after standing quickly.Which finding could provide a clue regarding the cause?

Accepted Answer

Poor skin turgor could suggest dehydration.Dehydration can cause orthostatic hypotension because of low capacitance reserves from hypovolemia.Supine blood pressure of 146/93 mm Hg would be considered hypertensive,and the patient would most likely experience a headache rather than dizziness.A resting heart rate of 96 beats/min is still considered a normal value.

Question 3

What is the name of outermost layer of an artery?

Accepted Answer

The adventitia is the outermost layer of the artery that helps strengthen and shape the vessel.The media is the middle layer that is made up of smooth muscle and elastic tissue.The intima is the innermost layer consists of a thin lining of endothelium and a small amount of elastic tissue.

Question 4

Which step of impulse conduction is most conducive to atrial kick?

Accepted Answer

The conduction delay at the atrioventricular (AV)node allows adequate time for ventricular filling from atrial contraction.

Question 5

A patient is admitted with right- and left-sided heart failure.The nurse's assessment reveals that the patient has 3+ pitting edema on the sacrum,blood pressure of 176/98 mm Hg,and bilateral crackles in the lungs.The patient is experiencing shortness of breath and chest discomfort.On the basis of this information,how would the nurse evaluate the patient's preload status?

Accepted Answer

Whereas a patient with hypovolemia has too little preload,a patient with heart failure has too much preload.

Question 6

What percentage of volume does atrial kick contribute to ventricular filling?

Accepted Answer

Atrial contraction,also known as "atrial kick," contributes approximately 20% of blood flow to ventricular filling; the other 80% occurs passively during diastole.

Question 7

Which statement regarding the autonomic nervous system's role in the regulation of heart rate is true?

Accepted Answer

The parasympathetic nervous system and the sympathetic nervous system operate to create a balance between relaxation and fight-or-flight readiness.They affect cardiovascular function by slowing the heart rate during periods of calm and increasing it in response to sympathetic stimulation.

Question 8

Why do many patients with very high heart rates frequently have chest pain and shortness of breath?

Accepted Answer

The coronary arteries are perfused during diastole.When the heart rate increases,the diastolic time decreases as each contraction has less time to be completed.This decreases the time the coronary arteries have to deliver oxygenated blood to the myocardium.The symptoms described are caused by a lack of oxygen in the myocardium.

Question 9

Which of the following values reflects a normal cardiac output at rest?

Accepted Answer

Cardiac output is normally expressed in liters per minute (L/min).The normal cardiac output in the human adult is approximately 4 to 8 L/min.It is approximately 4 to 6 L/min at rest and increases with exercise.

Question 10

Which phase is the final repolarization phase of the action potential?

Accepted Answer

The final repolarization phase is phase 3 of the action potential.Phases 1 and 2 (partial repolarization)occur as the AP slope returns toward zero.The plateau that follows is described as phase 2.In phase 4 the AP returns to an RMP of -80 to -90 mV.

Question 11

What is the normal resting membrane potential of a myocardial cell?

Accepted Answer

In a myocardial cell,the normal resting membrane potential is -80 to -90 mV.

Question 12

A patient presents with atrial fibrillation,a heart rate of 156 beats/min,and a blood pressure of 124/76 mm Hg.The practitioner orders diltiazem,a calcium channel blocker,to be given slowly by intravenous push.Why did the practitioner choose this medication to treat this patient's atrial tachyarrhythmia?

Accepted Answer

Calcium channel-blocking drugs,such as verapamil and diltiazem,inhibit the inward Ca++ current into pacemaker tissue,especially the atrioventricular (AV)node.For this reason,they are used therapeutically to slow the rate of atrial tachydysrhythmias and protect the ventricle from excessive atrial impulses.

Question 13

What is one hemodynamic effect of a pericardial effusion?

Accepted Answer

If the fluid collection in the sac (pericardial effusion)impinges on ventricular filling,ventricular ejection,or coronary artery perfusion,a clinical emergency may exist that necessitates removal of the excess pericardial fluid to restore normal cardiac function.Myocardial ischemia is damage of the myocardium muscle as the result of a heart attack.

Question 14

What is the function of the atrioventricular (AV)valves?

Accepted Answer

The atrioventricular (AV)valves are open during ventricular diastole (filling)and prevent backflow of blood into the atria during ventricular systole (contraction).Semilunar valves prevent the backflow of pulmonic and aortic blood back into the ventricles.

Question 15

A patient is admitted with a diagnosis of acute myocardial infarction.The monitor pattern reveals bradycardia.Occlusion of which coronary artery most likely resulted in bradycardia from sinoatrial node ischemia?

Accepted Answer

The right coronary artery provides the blood supply to the sinoatrial and atrioventricular (AV)nodes in more than half the population.The left coronary artery is a short but important artery that divides into two large arteries,the left anterior descending and the circumflex arteries.These vessels serve the left atrium and most of the left ventricle.The term dominant coronary artery is used to describe the artery that supplies the posterior part of the heart.

Question 16

Depolarization of one myocardial cell will likely result in what physiologic response?

Accepted Answer

The cardiac muscle is a functional syncytium in which depolarization started in any cardiac cell is quickly spread to all of the heart.

Question 17

Which of the following is most descriptive of the capillary?

Accepted Answer

The diameter of a capillary is less than that of an arteriole,but the pressure is relatively low as a result of the large cross-sectional area of the branching capillary bed.

Question 18

Which structure is the primary or natural pacemaker of the heart?

Accepted Answer

With an intrinsic rate of 60 to 100 beats/min,the sinoatrial node is the primary pacemaker in a healthy heart.The atrioventricular node beats 40 to 60 beats/min.Ventricular tissue must have an electrical impulse to contract.Purkinje fibers beat 15 to 40 beats/min.

Question 19

The atrioventricular (AV)node delays the conduction impulse from the atria (0.8-1.2 seconds)for what reasons?

Accepted Answer

The atrioventricular (AV)node delays the conduction impulse from the atria (0.8-1.2 seconds)to provide time for the ventricles to fill during diastole.

Question 20

Which is an example of a physiologic shunt?

Accepted Answer

The thebesian vessels return blood to the left ventricle.The mixing of unoxygenated blood with freshly oxygenated blood is called a physiologic shunt.A ventricular septal defect (VSD)allows mixing of blood from both ventricles.The clinical impact depends on the size of the intracardiac shunt.A VSD is a congenital opening between the ventricles; a ventricular septal rupture can occur as a complication of a large anterior wall myocardial infarction.

Quiz 11: Cardiovascular Anatomy and Physiology