Cardiac conduction and rhythm prepU
A nurse is caring for a client with an average heart rate of 56 beats/min. The client has no adverse symptoms associated with this heart rate and is receiving no treatment. Which activity modification should the nurse suggest to avoid further slowing of the heart rate? "Avoid stress or overexcitement." "Avoid bearing down while having a bowel movement." "Avoid strenuous aerobic exercise." "Limit your intake of caffeinated drinks."
Correct response: "Avoid bearing down while having a bowel movement." Explanation: Bearing down during a bowel movement stimulates the vagus nerve and results in a slowing of the heart rate. Vagal stimulation as well as some medications decreases the firing rate of the sinoatrial node and conduction through the atrioventricular node to cause a decrease in heart rate.
A nurse educator is teaching a group of nurses at a long-term care facility about atrial fibrillation in light of its prevalence in older adults. Which statement by the nurses would the educator most want to correct? "The electrical impulses go in chaotic directions and so the atria can't contract properly." "An ECG of someone in atrial fibrillation would be almost random in appearance." "The contraction of the ventricles and the atria can range from 400-600 beats per minute." "It can be hard to measure at the bedside because not all ventricular beats make a palpable pulse."
Correct response: "The contraction of the ventricles and the atria can range from 400-600 beats per minute." Explanation: While atrial contraction can range from 400-600 beats per minute, ventricular contraction is normally in the range of 80-180 beats per minute during atrial fibrillation. The electrical impulses do go in chaotic, inappropriate directions and the ECG can appear random. Measurement can be challenging because of the lack of pulses corresponding to all ventricular contractions.
Which client should the nurse be assessing for long QT syndrome? 95-year-old Alzheimer client who is having periods of apnea. 32-year-old male admitted for cocaine overdose with long history of illicit drug abuse 56-year-old female admitted for total hysterectomy due to excessive bleeding and clotting 68-year-old male who was in a car accident with sterna bruising and fractured femur
Correct response: 32-year-old male admitted for cocaine overdose with long history of illicit drug abuse Explanation: Acquired LQTS has been linked to a variety of conditions, including cocaine use, exposure to organophosphorus compounds, electrolyte imbalances, marked bradycardia, MI, SAH, HIV, and protein-sparing fasting
A client with a past medical history of congestive heart failure is admitted to the hospital with severe palpitations and a heart rate of 170, blood pressure 88/60. Home medications include digoxin, a loop diuretic, and a baby aspirin. The physician has diagnosed the client with focal atrial tachycardia and is discussing the treatment options with the client. Which action would most likely be ordered first? Insertion of a permanent pacemaker Correction of the underlying cause Radiofrequency catheter ablation Echo-guided cardioversion
Correct response: Correction of the underlying cause Explanation: The most effective way to treat focal atrial tachycardia is to treat the underlying cause. In this case the most likely cause is digoxin toxicity. This client is on digoxin and a loop diuretic, which could lower potassium levels making the risk of digoxin toxicity much more likely. Antiarrhythmic medications and radiofrequency catheter ablation would be considered if the underlying cause cannot be determined or treatment fails.
A client's electrocardiogram monitor begins to sound an alarm and shows sustained ventricular fibrillation. The client is unconscious and without a pulse. Which priority intervention should the nurse take? Defibrillate the client Administer IV push atropine Perform synchronized cardioversion Notify the client's attending physician
Correct response: Defibrillate the client Explanation: Immediate defibrillation using a nonsynchronized, direct-current electrical shock is mandatory for ventricular fibrillation and for ventricular flutter that has caused loss of consciousness.
The nurse is assisting a client who had a myocardial infarction 2 days ago during a bath. The client suddenly lost consciousness and the nurse was unable to feel a pulse. Cardiopulmonary resuscitation was begun and the client was connected to the monitor with a gross disorganization without identifiable waveforms or intervals observed. What is a priority intervention at this time? Immediate defibrillation Synchronized cardioversion Applying a transcutaneous pacemaker Administration of atropine
Correct response: Immediate defibrillation Explanation: The classic electrocardiographic pattern of ventricular fibrillation is that of gross distortion without identifiable waveforms 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.
Nursing students who are studying for their upcoming cardiac exam are discussing how the heart could possibly continue to beat once removed from the body. One of the students explains that this phenomenon is directly related to automaticity. What is automaticity? Inherent spontaneous action-potential Inherent discharge rate of 60-80 Inherent low-impulse conductivity Inherent discharge rate of 40-60
Correct response: Inherent spontaneous action-potential Explanation: The heart has four inherent properties essential in the development and conduction of cardiac rhythms. The property of automaticity is the ability of certain cells in the myocardium to automatically or spontaneously initiate an electrical impulse called an action potential. In a normally functioning heart the rate is controlled by the sinoatrial (SA) node.
A monitored hospitalized client with a pulmonary embolism has been in atrial fibrillation (AF) for 4 days. The nurse observes the rhythm spontaneously convert to a normal sinus rhythm. Which form of AF is this? Chronic Permanent Paroxysmal Persistent
Correct response: Paroxysmal Explanation: AF is characterized as rapid disorganized atrial activation and uncoordinated contraction by the atria. It is classified into three categories: paroxysmal, persistent, and permanent. Paroxysmal AF self-terminates and lasts no longer than 7 days, whereas persistent lasts greater than 7 days and usually requires intervention such as a cardioversion. AF is classified as permanent when attempts to terminate are failed and the person remains in AF. The symptoms of chronic AF vary. Some people have minimal symptoms, and others have severe symptoms, particularly at the onset of the dysrhythmias.
A client with supraventricular tachycardia has received a dose of verapamil to slow the heart rate. Which explanation describes the effect of this drug on the heart? Slows the sinoatrial (SA) node pacemaker and inhibits conduction in the atrioventricular (AV) node Blocks the fast sodium channels Blunts the effect of the sympathetic nervous system stimulation on the heart Reduces periods of cardiac refraction
Correct response: Slows the sinoatrial (SA) node pacemaker and inhibits conduction in the atrioventricular (AV) node Explanation: Class IV drugs (e.g., verapamil, diltiazem, mibefradil) act by blocking the slow calcium channels, thereby depressing phase 4 and lengthening phases 1 and 2 of the action potential. By blocking the release of intracellular calcium ions, these agents reduce the force of myocardial contractility, thereby decreasing myocardial oxygen demand. These drugs are used to slow the SA node pacemaker and inhibit conduction in the AV node, slowing the ventricular response in atrial tachycardias, and to terminate reentrant paroxysmal supraventricular tachycardias when the AV node functions as a reentrant pathway.
