Authors

  1. Brewer, Sharon MSN, RN, CNE
  2. Seth, Shelly DNP, MBA, RN, CCRN-K, ACNP, FNP

Article Content

Ms. G woke up feeling fine and went to work like always. At 11:30 a.m. while talking with friends after a meeting, she suddenly became short of breath. She felt her pulse and noted that it was very rapid and irregular. She began feeling weak and sat down. A friend drove her to the ED where she was placed on a cardiac monitor. Her pulse was noted to be 180 beats/minute and irregular in rhythm. She was diagnosed with sudden-onset atrial fibrillation (AF) with rapid ventricular response and admitted to the hospital.

  
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According to the CDC, an estimated 2.7 million to 6.1 million people in the US have AF. It's the most common type of sustained cardiac arrhythmia and occurs when the electrical activity of the heart's atria becomes disorganized. The incidence of AF increases with age and is more common in women and those of European descent. More than 750,000 people are hospitalized each year with the signs and symptoms of AF, and the condition causes about 130,000 deaths annually.

 

AF is a major health concern that's associated with significant morbidity and mortality. The treatment of AF in the US alone incurs a cost of approximately $6 billion. Medical costs for people with AF are about $8,700 more per year compared with those who don't have AF. Quality of life may be preserved with early recognition and intervention to prevent stroke.

 

Pathophysiology

The natural pacemaker of the heart, called the sinus node or sinoatrial (SA) node, controls the heart's rate and rhythm when everything is functioning normally. For each heartbeat, the SA node creates an electrical impulse that travels across the atria, through the atrioventricular (AV) node, down the right and left bundle branches, and into the ventricular muscle, producing cardiac contraction. AF occurs when there's a disruption in the generation of impulses and the flow of electricity in the atria.

 

Electrical impulses originate from multiple foci in the atria and bombard the AV node (see Cardiac conduction). If the impulses become too rapid, the AV node becomes unable to filter them appropriately, and the ventricular rate may increase significantly. Common underlying conditions that contribute to AF include ischemic heart disease, cardiac valvular disease, hypertension, heart failure, electrolyte disturbances such as low magnesium, and acute infection.

 

AF is common for the first several days following coronary artery bypass graft surgery. Other common risk factors include age older than 65, obesity, diabetes, smoking, sleep apnea, substance abuse, and hyperthyroidism.

 

What to look for

A patient with undiagnosed AF may present to the clinic or ED with a variety of symptoms, such as:

 

* palpitations-commonly felt as a fluttering in the chest

 

* tiredness or fatigue-atrial kick produces up to 30% of the cardiac output and is lost when atrial contractions cease as in AF

 

* shortness of breath-with a decrease in cardiac output, the oxygen-carrying capacity of the blood is also decreased

 

* dizziness-often occurs with a sudden decrease in cardiac output

 

* irregularly irregular pulse

 

* narrow, uniform QRS complexes occurring in an irregularly, irregular pattern; P waves are replaced with fibrillatory waves appearing in a chaotic pattern on the ECG (see A closer look at AF).

 

 

Many patients who present with AF have no symptoms. Patients who have untreated AF for 48 hours or more are at a significantly increased risk for forming blood clots that can result in an embolic stroke. This is due to the congestion of blood in the atria that accumulates as a result of the loss of atrial contraction.

 

It's important for all patients with risk factors to receive an assessment that includes palpating the pulses and auscultating the chest for the irregularity of AF. Automatic vital signs machines, which display the BP and heart rate as a number, don't fulfill this assessment. Due to the irregularity of the AF pulse, nurses may detect this dysrhythmia by palpating the pulse, auscultating heart sounds, and taking a manual BP on at-risk patients. A follow-up ECG will either confirm the diagnosis or rule it out.

 

Treatment options

In the ED, Ms. G's blood was drawn and a 12-lead ECG was completed. Her vital signs were: BP, 160/84; heart rate, 180; respirations, 16; and oxygen saturation, 96%. Her skin was warm and dry, and she was alert and oriented. Enoxaparin was administered subcutaneously. Additional treatment options were aimed at achieving a normal sinus rhythm and included medications or synchronized cardioversion. The physician discussed the risks and benefits of each, and Ms. G agreed to proceed with synchronized cardioversion. The medication regimen was implemented following two unsuccessful attempts at cardioversion. Ms. G was placed on I.V. beta-blockers and admitted to the CCU, where she converted to a normal sinus rhythm. She was discharged 2 days later with oral anticoagulation and antiarrhythmic therapy.

 

The treatment goal for AF is to control the heart's rate and rhythm and prevent blood clot formation, which may result in stroke. If the dysrhythmia begins and ends suddenly, it's considered paroxysmal AF; however, if it lasts more than 7 days, it's considered persistent. Thrombi are more prone to form in the atria after 48 hours, and the risk of embolic stroke increases significantly without appropriate anticoagulation.

 

Treatment options for AF include:

 

* anticoagulation medication to prevent blood clots from forming and reduce stroke risk

 

* medications to control the heart's rhythm and rate

 

* synchronized cardioversion, if indicated, to attempt to return the cardiac rhythm to a normal sinus rhythm

 

* catheter ablation for symptomatic patients with AF who are unable to be converted to sinus rhythm through either medication or cardioversion

 

* healthy lifestyle changes to manage AF risk factors.

 

 

Using the CHA2DS2-VASc criteria, each patient is assessed for eight risk factors, including congestive heart failure, hypertension, age 75 or older, diabetes mellitus, stroke/transient ischemic attack/thromboembolic event, vascular disease, ages 65 to 74, and female sex. Each criterion is scored as 0, 1, or 2 points. If the total score is 0, oral anticoagulation therapy isn't recommended, but aspirin may be considered. If the score is 1, consider oral coagulation therapy or aspirin. For scores of 2 or more, oral anticoagulation therapy is recommended. It's stroke risk rather than the presence or absence of sinus rhythm that determines the need for anticoagulation therapy.

 

Warfarin has long been a mainstay of anticoagulation therapy. It has many drug-drug and food-drug interactions, and the patient's international normalized ratio must be monitored closely. Vitamin K is available as a reversal agent. Warfarin is affordable for most patients.

 

Newer anticoagulation therapies include dabigatran, rivaroxaban, edoxaban, and apixaban. These medications work as direct thrombin inhibitors or as direct factor Xa inhibitors. The newer agents generally have fewer interactions and no required labs but are more expensive.

 

Patients should discuss the risks and benefits of each medication with their healthcare provider to determine the best treatment option. Without anticoagulation therapy, the patient experiencing AF has an approximately fivefold risk of stroke.

 

Beta-blockers provide safe and effective control of the heart rate in patients with AF. These medications slow the sinus rate and decrease AV nodal conduction. Calcium channel blockers are commonly administered and are associated with an improvement in exercise tolerance. Use with caution in the presence of heart failure or chronic obstructive pulmonary disease.

 

Amiodarone may be an alternative for heart rate control when other medications aren't effective. Adverse reactions associated with amiodarone include pulmonary fibrosis, hepatic damage, and proarrhythmia. Baseline studies should be performed before implementing treatment with amiodarone.

 

Digoxin is no longer considered a first-line treatment for AF but may be given in combination with other medications.

 

In addition to medications, synchronized cardioversion and catheter ablation are treatment options for some patients.

 

In synchronized cardioversion, an electrical shock is delivered to the heart to interrupt the abnormal cardiac cycle and reset the electrical activity to normal sinus rhythm. This shock is timed, or synchronized, with the ECG complex and delivered on the R wave. This is accomplished by engaging the "SYNC" button on the defibrillator. Except in emergent situations, informed consent is obtained and the patient is sedated. Maintenance of airway and breathing during this procedure is a priority. If unsuccessful on the first attempt, the shock may be repeated using a higher energy setting.

 

For patients with symptomatic AF unresponsive to treatment, catheter ablation may be considered. Following an electrophysiology study, special catheters are inserted into the heart and used to create small areas of scar tissue (ablation lines) to prevent the flow of abnormal electrical impulses. This is usually accomplished using either radio frequency waves or cryothermy. Patient care and recovery are similar to a cardiac catheterization procedure.

 

Patient teaching

Studies show that patient-centered approaches may help optimize management among AF patients, and a shared decision-making approach may improve anticoagulation therapy adherence. Education may be reinforced by smart technology, such as smartphone apps.

 

Advise the at-risk patient to report symptoms such as irregular heartbeat, heart palpitations, lightheadedness, fatigue, dyspnea, and/or chest pain. Anticoagulation therapy for stroke prevention increases the risk of serious bleeding. Patient teaching should emphasize the rationale for the use of coagulation-modifying drugs. Instruct the patient to take medications exactly as prescribed because too much may cause bleeding and too little may result in clot formation. Encourage the patient to wear a medical-alert bracelet and report any unusual bleeding, severe headache, dizziness, or blurred vision. Advise the patient to use a soft-bristled toothbrush and safety razors, and avoid activities that may result in injury such as contact sports.

 

Teach the patient to avoid triggers associated with AF, such as stimulants, caffeine, alcohol, smoking, certain medications, and high-intensity physical stress. Medications to avoid or use with caution include decongestants, such as pseudoephedrine; adrenergic stimulants, such as atropine; bronchodilators, such as albuterol or aminophylline, thyroid hormone replacement; and stimulants, such as cocaine, methamphetamines, and other street drugs. Patients with AF should discuss all medications and herbal supplements with their healthcare provider before starting use. Lifestyle modifications should address regular exercise; weight reduction; smoking cessation; and management of hypertension, diabetes, and stress.

 

Reducing the risk

AF is a common healthcare concern with substantial risks to patient health. Early recognition and treatment are essential to prevent significant adverse outcomes. Nurses can contribute to early identification of this dysrhythmia by properly assessing the at-risk patient through pulse palpation and heart auscultation. Early intervention may improve patient health and quality of life, as well as prevent the devastating effects of embolic stroke.

 

Cardiac conduction

(A) The heart's electrical circuitry has a profound effect on efficient blood flow to the tissues. An electrical impulse from the SA node travels over the internodal pathways to produce atrial contraction. The impulse slows slightly as it nears the ventricles at the AV node (the AV junction). After passing through the bundle of His, the impulse descends along the left and right bundle branches to the Purkinje fibers, stimulating ventricular contraction and proceeding on to the SA node to continue the cycle. The efficiency of the conduction system has a major influence on cardiac rhythm and output reflected by blood flow. (B) This is the pattern of one cardiac cycle on an ECG. Note the components of the complex, including the waves and intervals: P wave, PR interval, PR segment; Q,R, and S waves, QRS complex; ST segment, QT interval.

 

A closer look at AF

The following rhythm strip shows AF.

  
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* Rhythm: irregular * Rate: atrial-indiscernible; ventricular-130 beats/minute * P wave: absent; replaced by fine fibrillatory waves * PR interval: indiscernible * QRS complex: 0.08 s * T wave: indiscernible * QT interval: unmeasurable * Other: none

 

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