Chap. 33: Disorders of Cardiac Conduction and Rhythm

A patient who will be undergoing a Holter monitor examination would be given which of the following instructions?

"Keep a diary of your activities and symptoms throughout the examination." During the period of a patient wearing a Holter monitor (usually 48 hours), the patient will be instructed to maintain a diary of activities and symptoms so that the recorded electrocardiographic reading can be correlated with the diary events. The other options are not instructions appropriate for a Holter monitor examination.

A nurse is caring for a patient with an average heart rate of 56 beats/min. The patient has no adverse symptoms associated with this heart rate and is receiving no treatment. Which of the following activity modifications should the nurse suggest to avoid further slowing of the heart rate?

"Avoid bearing down while having a bowel movement." 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 client is admitted to the hospital with severe bradycardia, heart rate in low to upper 40s, after contracting Lyme disease. She asks the nurse why the heart rate is so slow. The most accurate response would be a possible disassociation between the atria and ventricles due which of the following?

AV nodal block Disassociation between the atria and ventricles interrupts the communication between them and they each beat with their own different regular rates. Therefore an AV nodal block would cut off communication between the atria and ventricles causing the area below the AV node to pace the ventricles. When this disassociation occurs and the heart rate is 40 to 60 per minute the block is typically proximal to the bundle of his.

A client has been diagnosed with atrial flutter. What assessment finding does the nurse expect?

An atrial heart rate above 240 beats per minute Atrial flutter is a rapid atrial ectopic tachycardia and has an atrial rate from 240 to 450 beats per minute. The ventricular rate would not be expected to be as high as 240 beats per minute, and the blood pressure would not be expected to increase.

The nurse is caring for a patient who has been admitted to the hospital with a diagnosis of unstable angina and the client wants to know why daily ECGs are necessary. The nurse explains that the ECGs can pick up early indications of cardiac ischemia and the nurse knows that according to the American Heart Association practice standards, the client falls into which of the following ECG monitoring categories?

Class I The AHA in collaboration with the North American Society for Pacing and Electrophysiology developed guidelines for practitioners to use with clients who have known cardiac disease to detect untoward indications of imminent or progressing cardiac ischemia, infarction and/or arrhythmias. Cardiac monitoring is necessary for most clients in Class I.

A client has been admitted after being resuscitated from a cardiac arrest. The client is stated to be in Class I for electrocardiogram monitoring. What type of monitoring will the nurse perform for this client?

Continuous cardiac monitoring The American Heart Association has published practice standards for electrocardiogram monitoring in hospital settings. The rating system has three categories. Class I clients require cardiac monitoring consistently. Class II clients may need monitoring but it is not essential. Class III clients do not have monitoring indicated.

A patient's electrocardiogram monitor begins to sound an alarm and shows sustained ventricular fibrillation. The patient is unconscious and without a pulse. Which of the following priority interventions should the nurse take?

Defibrillate the patient 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 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.

Which of the following is the greatest diagnostic limitation of an electrocardiogram (ECG)?

It documents only current cardiac function. The resting ECG is the first approach to the clinical diagnosis of disorders of cardiac rhythm and conduction, but it is limited to events that occur during the period the ECG is being monitored. The other options are not accurate statements regarding an ECG.

ECG monitoring has been found to be more sensitive than a client's report of symptoms when identifying transient ongoing myocardial ischemia. Why is this?

Most ECG-detected ischemic events are clinically silent. Persons with acute coronary syndrome are at risk for developing extension of an infarcted area, ongoing myocardial ischemia, and life-threatening arrhythmias. Research has revealed that 80% to 90% of ECG-detected ischemic events are clinically silent. Thus, ECG monitoring is more sensitive than a client's report of symptoms for identifying transient ongoing myocardial ischemia. Other answers are incorrect.

A client arrives at the doctor's office complaining of severe indigestion that has been intermittent; however, the pain is now constant and feels like a vise. The nurse does an ECG and recognizes that the situation is possibly emergent due to ST-segment elevation, which could indicate which of the following?

Myocardial infarction The ST-segment elevation with myocardial infarction could be caused by a decrease in blood supply to that area of cardiac muscle. However, the mechanism of ST-segment elevation is not clearly understood. The other options with this question are the opposite of other causes of ST-segment elevation.

A monitored hospitalized patient 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 of the following forms of AF is this?

Paroxysmal 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 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 arrhythmia.

Which of the following occurs during repolarization?

Positively charged K+ moves outward across the cell membrane During rapid repolarization period, the slow Ca++ channels close and the influx of Ca++ and Na+ ceases. There is a sharp rise in K+ permeability, contributing to the rapid outward movement of K+ and reestablishing the resting membrane potential.

A patient experiencing a sinus arrest would demonstrate which of the following symptoms or findings?

Prolonged periods of asystole demonstrated on an electrocardiogram The patient with sinus arrest refers to failure of the sinoatrial node to discharge and results in an irregular pulse, prolonged periods of asystole, and predisposition to other arrthythmias. The other options do not demonstrate the symptoms demonstrated during a sinus arrest.

The nurse is interpreting an electrocardiogram of a 65-year-old woman. Which should the nurse recognize as representing ventricular depolarization?

QRS complex The QRS complex is representative of ventricular depolarization. The P wave is atrial depolarization, the T wave is ventricular repolarization, and the ST segment is the time to ventricular repolarization.

A patient is seen in the emergency department complaining of chest discomfort, productive cough, and a fever of over 101°F for 3 days. The nurse performs an electrocardiogram and observes a rate of 110 beats per minute (bpm) with a normal P wave and a PR interval of 0.12 sec preceding each QRS complex. Which of the following does the nurse determine the rhythm to be?

Sinus tachycardia Sinus tachycardia is a heart rate >100 bpm that has its origin in the sinoatrial node. A normal P wave and PR interval should precede each QRS complex. The mechanism of sinus tachycardia is enhanced automaticity, related to sympathetic stimulation or withdrawal of vagal tone. Sinus tachycardia is a normal response during any increase in metabolic activity such as fever, stress, anxiety, and the like.

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 premature ventricular complexes can occur in healthy hearts in response to stimulation of the sympathetic nervous system. This client states nighttime studying (possibly with coffee intake) and stress over upcoming exams, both of which can stimulate the sympathetic nervous system.

Which client will the nurse prioritize to assess first?

The client with sinus arrest The client with sinus arrest refers to failure of the SA node to discharge and results in an irregular pulse. An escape rhythm develops as other pacemakers take over, but it may result in prolonged periods of asystole and other abnormal rhythms. The client may need further interventions such as a pacemaker. The other clients need monitoring; however, their rhythm is not placing them in need of immediate assistance.

Which type of pacing involves the placement of large patch electrodes on the anterior and posterior chest wall that can be connected by a cable to an external pulse generator?

Transcutaneous The type of pacing described is transcutaneous because it is only form that is accessible externally.

Which of the following arrhythmias is considered to be the most fatal and requires immediate treatment?

Ventricular fibrillation Ventricular fibrillation represents severe derangements of cardiac rhythms that terminate fatally within minutes unless corrective measures are taken promptly. All of the other arrhythmias need to have further investigation into etiology, but are not immediately fatal.

A new intensive care unit nurse is taking a cardiac arrhythmia course in preparation for working in the unit. The instructor is discussing sinus arrest and states that there are pathological and non-pathological causes for this rhythm. Which of the following could cause this rhythm? Select all that apply.

• Acute bacterial myocarditis • K+ greater than 6 • K+ less than 3 There are a number of diseases, conditions and medications that can contribute to sinus arrest, including acute myocarditis caused by bacteria or other pathogens, hyperkalemia (K+ above 5.3), and hypokalemia (K+ less than 3.5). Thyroid disorders do not affect the SA node.

A 70-year-old client with a past medical history of diabetes type II and myocardial infarction (MI) is admitted to the hospital with sudden shortness of breath and palpitations. As the nurse is doing the admission assessment she notices that the apical pulse is very irregular with no pattern, vital signs include a heart rate of 130 and blood pressure of 100/60. The nurse suspects atrial fibrillation (AF) for which of the following reasons? Select all that apply.

• Palpitations • Irregular-irregular rhythm • Tachycardia The typical signs and symptoms with atrial fibrillation are palpitations, tachycardia and an extremely irregular rhythm, along with fatigue. The incidence of atrial fibrillation increases with increased age and can be seen with clients who have no disease or those with hypertension, congestive heart failure, myocardial infarction, hyperthyroidism, along with many other disorders.