Patho Ch.17
As part of their orientation to a cardiac care unit, a group of recent nursing graduates is receiving a refresher in cardiac physiology from the unit educator. Which of the following teaching points best captures a component of cardiac function?
"The diastolic phase is characterized by relaxation of ventricles and their filling with blood."
A heart failure client has an echocardiogram performed revealing an ejection fraction (EF) of 40%. The nurse knows this EF is below normal and explains to the client:
"This means your heart is not pumping as much blood out of the heart with each beat." Ejection fraction is the percentage of diastolic volume ejected from the heart [left ventricle] during systole. Stroke volume is determined by the difference between end-diastolic and end-systolic volumes. Cardiac output is determined by stroke volume and heart rate. Cardiac reserve refers to the maximum percentage of increase in cardiac output that can be achieved above the normal resting level.
A client asks why he has not had major heart damage since his cardiac catheterization revealed he has 98% blockage of the right coronary artery. The nurse's best response is:
"You have small channels between some of your arteries, so you can get blood from a patent artery to one severely blocked."
A local athlete is getting prepared for the upcoming national track and field championships. Since this athlete is performing extreme exercise, what would be the most probable cardiac output?
16 to 36 L/minute The average cardiac output in resting normal adults ranges from 4 to 6 L/minute. Less than this indicates cardiac disease. If a highly trained athlete is performing at an extreme exercise level, the heart may be required to pump four to six times this amount, or 16 to 36 L/minute.
A number of patients on an acute cardiac care unit of a hospital have diagnoses of impaired cardiac conduction. Which of the following patients is most deserving of immediate medical attention?
A 69-year-old woman who has entered ventricular fibrillation. Ventricular fibrillation, or ventricular flutter, is a life-threatening emergency that would necessitate immediate intervention. Ventricular tachycardia is also a serious condition, but less so than ventricular fibrillation. PVCs and a first-degree AV block would not normally require emergency intervention.
In which situation is blood most likely to be rapidly relocated from central circulation to the lower extremities?
A client is helped out of bed and stands up
A client is admitted to the cardiac unit with a diagnosis of pericarditis. The nurse is teaching the patient about the anatomical location of the infection. The nurse evaluates the effectiveness of the teaching when the client correctly identifies which of the following as the location of the pericardium?
A membranous sac that encloses the heart
Which factor represents the contractile force used by the muscle to move blood into the aorta?
Afterload The afterload is the pressure in which the muscle exerts its contractile force in order to move blood into the aorta. It is called the afterload because it is the work presented to the heart after contraction.
A client's echocardiogram identified a narrowed valve that has resulted in a decreased blood flow between the left atria and left ventricle. The nurse would interpret this as the:
Bicuspid valve
Cardiac output (CO) is used to measure the efficiency of the heart as a pump. What is the equation used to express CO?
CO = SV × HR
Select the correct sequence of blood return to the heart.
Capillaries, venules, veins, right atrium
A client is admitted to the emergency department after experiencing a motor vehicle accident and sustaining multiple injuries with significant blood loss. The nurse predicts that the client will display which of the following?
Decreased urinary output Stimulation of the sympathetic nervous system during stress or exercise causes local constriction of veins and arterioles due to the release of norepinephrine from sympathetic nerve endings. Increasing sympathetic activity causes constriction of some vessels, such as those of the skin, the gastrointestinal tract, and the kidneys. Vasoconstriction results in decreased blood flow to the kidneys and a compensatory decrease in urinary output and an increase in heart rate. Collateral circulation is a mechanism for long-term regulation of blood flow.
In the days following a tooth cleaning and root canal, a client has developed an infection of the thin, three-layered membrane that lines the heart and covers the valves. What is this client's most likely diagnosis?
Endocarditis
The school nurse is doing a health class on the functional organization of the circulatory system. What is the function of the capillaries in the circulatory system?
Exchange gases, nutrients and wastes
The nurse is assisting a patient who had a myocardial infarction 2 days ago during a bath. The patient suddenly lost consciousness and the nurse was unable to feel a pulse. Cardiopulmonary resuscitation was begun and the patient was connected to the monitor with a gross disorganization without identifiable waveforms or intervals observed. Which of the following is a priority intervention at this time?
Immediate defibrillation The classic electrocardiographic pattern of ventricular fibrillation is that of gross distortion without identifiable waveforms or or intervals. When the ventricles do not contract, there is no cardiac output, and there are no palpable or audible pulses. Immediate defibrillation using a nonsynchronized, direct-current electrical shock is mandatory for ventricular fibrillation and for ventricular flutter that has caused loss of consciousness.
A client has experienced sympathetic nervous stimulation of the heart. The nurse is aware that the client may manifest which of the following?
Increased heart rate and increased contractility
Which of the following is true regarding pulmonary circulation?
It is a low-pressure system that allows for improved gas exchange.
Which of the following blood flow patterns reduces friction, allowing the blood layers to slide smoothly over one another?
Laminar
When the semilunar valves open it signals the onset of the ejection period. The aortic pressure reflects changes in the ejection of blood from which part of the heart?
Left ventricle
A nurse is assessing a female client and notes that her left arm is swollen from the shoulder down to the fingers, with non-pitting edema. The right arm is normal. The client had a left-sided mastectomy one year ago. Which of the following does the nurse suspect is the problem?
Lymphedema The lymphatic system filters fluid at the lymph nodes and removes foreign particles such as bacteria. When lymph flow is obstructed, a condition called lymphedema occurs. Involvement of lymphatic structures by malignant tumors and removal of lymph nodes at the time of cancer surgery are common causes of lymphedema.
Nitroglycerin is the drug of choice in treating angina. What does nitroglycerin release into the vascular smooth muscle of the target tissues?
Nitric oxide The fact that nitric oxide is released into the vessel lumen (to inactivate platelets) and away from the lumen (to relax smooth muscle) suggests that it protects against both thrombosis and vasoconstriction. Nitroglycerin, which is used in treatment of angina, produces its effects by releasing nitric oxide in vascular smooth muscle of the target tissues. None of the other options are released by nitroglycerin.
Considering the PQRST complex of an electrocardiogram (ECG), which of the following letter designations represents atrial depolarization?
P wave
The nurse assesses the electrocardiogram for depolarization of the atria. What does the nurse expect to assess?
P wave above the baseline
A nurse is caring for a client with right heart failure caused by pulmonary hypertension. Which hemodynamic parameter is most appropriate for the nurse to monitor?
Pulmonary arterial pressure (PAP) The pulmonary arterial pressure is the main source of afterload work on the right heart.
The electrical activity of the heart is recorded on the ECG. What does the T wave on the ECG represent?
Repolarization of the ventricles The P wave represents the depolarization of the sinoatrial node. The QRS complex represents the depolarization of the ventricles. The T wave represents repolarization of the ventricles, not the atrium.
When trying to explain to a new dialysis patient the movement of substances through the capillary pores, the nurse will explain that in the kidneys, the glomerular capillaries have:
Small openings that allow large amounts of smaller molecular substances to filter through the glomeruli.
The cardiologist just informed a patient that they have a reentry circuit in the electrical conduction system in their heart. This arrhythmia is called Wolff-Parkinson-White (WPW) syndrome. After the physician has left the room, the patient asks the nurse to explain this to them. Which of the following statements most accurately describes what is happening?
There is an extra, abnormal electrical pathway in the heart that leads to impulses traveling around the heart very quickly, in a circular pattern, causing the heart to beat too fast."
The cardiac cycle describes the pumping action of the heart. Which statement is correct about systole?
Ventricles contract and blood is ejected from the heart.
A male patient with a history of angina has presented to the emergency department with uncharacteristic chest pain. His subsequent electrocardiogram (ECG) reveals T-wave elevation. This finding suggests an abnormality with which of the following aspects of the cardiac cycle?
Ventricular repolarization
An 80-year-old male client arrives for his yearly physical without any complaints and following the checkup the physician explains that he has noted atrial fibrillation (AF) on the client's ECG. Before the physician can explain the disorder the client becomes very upset and states he thinks he is going to die. The physician explains that atrial fibrillation involves the top chambers of the heart and that:
many people live with atrial fibrillation without even knowing they have it. Atrial arrhythmias are typically less serious because they do not impact the ability of the ventricles to pump. This client is at high risk to develop atrial fibrillation due to his advanced age; the rates of atrial fibrillation begin to increase over the age of 60 and males have a greater prevalence. It is true that atrial fibrillation is a disorganized rhythm; however it is not ventricular. The client may or may not need anticoagulation; there are other considerations to be made before these medications would be considered.
A 20-year-old college student, with no past medical history, arrives at the emergency room complaining of severe palpitations and dizziness that started this morning following a night of studying. The student is very upset that this is happening because the final exams are the following day. The cardiac monitor shows a heart rate of 110, regular rhythm with occasional premature ventricular complexes. The nurse explains to the student that this can happen in healthy hearts and is usually caused by stimulation of which of the following?
sympathetic nervous system
Which of the following vessel layers is made primarily of muscle?
tunica media
The heart valves control the direction of blood flow. What is the function of the pulmonic valve?
Controls the direction of blood flow from the right side of the heart to the lungs
The physician states that a client has adequate collateral circulation. The nurse interprets this as:
Long-term compensatory regulation of blood flow
The nurse has completed an automated blood pressure and pulse reading on a client with persistent atrial fibrillation. The client's baseline values are blood pressure 130/85 mm Hg and heart rate of 80 bpm and irregular. The current result is blood pressure is 98/47 mm Hg, the heart rate is 77 bpm, and the client denies feeling differently. What is the nurse's priority action?
Perform a manual blood pressure and apical heart rate reading. The ventricular response in atrial fibrillation is completely irregular. Because of changes in stroke volumes resulting from varying periods of diastolic filling, not all ventricular beats produce a palpable pulse. Using an automated machine means some of the pulses required to assess blood pressure may be inaudible and result in an inaccurate reading. The nurse should verify the results using a manual reading of both blood pressure and apical heart rate. The nurse would also use the client's current symptoms as a guide to decision making but should not change the position, or notify the health care provider until the reading is verified. Analyzing a past electrocardiogram would also be unnecessary until the reading is confirmed.