Atrial Dysrhythmias (Premature Atrial Contraction & Atrial Fibrillation) Flashcards
What is a premature atrial complex/contraction?
A premature atrial complex (contraction) (PAC) occurs when atrial tissue becomes irritable. This ectopic focus fires an impulse before the next sinus impulse is due. The premature P wave may not always be clearly visible because it can be hidden in the preceding T wave. Examine the T wave closely for any change in shape and compare with other T waves. A PAC is usually followed by a pause.
What are some causes of atrial irritability that end up causing premature atrial complexes/contractions?
The causes of atrial irritability include:
- Stress
- Fatigue
- Anxiety
- Inflammation
- Infection
- Caffeine, nicotine, or alcohol
- Drugs such as epinephrine, sympathomimetics, amphetamines, digoxin, or anesthetic agents
What conditions may result in premature atrial contractions?
PACs may also result from myocardial ischemia, hypermetabolic states, electrolyte imbalance, or atrial stretch. Atrial stretch can result from congestive heart failure, valvular disease, and pulmonary hypertension with cor pulmonale.
How are premature atrial contractions treated?
- Monitor for more serious dysrhythmias
- Withhold sources of stimulation such as caffeine and alcohol.
- Administer beta blockers.
What are two types of premature atrial contractions?
- Atrial bigeminy: It is a premature atrial contraction on every second beat (every other beat) of the heart rhythm.
- Atrial trigeminy: It is a premature atrial contraction on every third beat of the heart.
What is the pathophysiology of atrial fibrillation (A-fib)?
In patients with AF, multiple rapid impulses from many atrial foci depolarize the atria in a totally disorganized manner at a rate of 350 to 600 times per minute; ventricular response is usually 120 to 200 beats/min. The result is a chaotic rhythm with no clear P waves, no atrial contractions, loss of atrial kick, and an irregular ventricular response. The atria merely quiver in fibrillation (commonly called A fib). Often the ventricles beat with a rapid rate in response to the numerous atrial impulses. The rapid and irregular ventricular rate decreases ventricular filling and reduces cardiac output. This alteration in cardiac function allows for blood to pool, placing the patient at risk for clotting concerns such as DVT or PE. AF is frequently associated with underlying cardiovascular disease
What conditions can put a person at risk for atrial fibrillation?
Heart diseases such as hypertension, heart failure, and coronary artery disease. For those without an underlying disorder leading to the development of AF, as many as 30 genetic mutations have been identified as the potential cause.
How is atrial fibrillation classified?
Atrial fibrillation is classified into five categories based on length of time in the rhythm: paroxysmal, persistent, long-standing persistent, permanent, and nonvalvular.
What are some descriptors that can help health care personnel identify a strip as being atrial fibrillation?
- Chaotic rhythm
- No P waves or no clear P waves can be seen
What should be assessed when obtaining a history from a patient with A-fib?
When obtaining a history, assess for prior history of AF or other dysrhythmias. Recurrence of AF is common, and assessment of previous conduction issues can be helpful in developing the plan of care. Assess for history of cardiovascular disease. The risk of AF is much higher in patients with a history of hypertension, heart failure, obesity, or acute coronary syndrome.
What are some physical assessment signs and symptoms for a patient with A-fib?
On physical examination, the apical pulse may be irregular. Symptoms depend on the ventricular rate. Because of the loss of atrial kick, the patient in uncontrolled AF is at greater risk for inadequate cardiac output. Signs of poor perfusion may be observed. Assess the patient for fatigue, weakness, shortness of breath, dizziness, anxiety, syncope, palpitations, chest discomfort or pain, and hypotension. Some patients may be asymptomatic.
What is included in the psychosocial assessment with a patient with A-fib?
Patients with AF, especially those with a high ventricular rate, can feel very anxious. With increased heart rate, cardiac output decreases, which can create dyspnea, contributing to feelings of anxiety. Assess patients who have chronic atrial fibrillation for methods of coping with a long-term conduction issue. Patients with chronic AF may have anxiety related to anticoagulation medications and the potential for emboli development.
What diagnostics can be performed for a patient with atrial fibrillation?
Definitive diagnosis occurs by obtaining a 12-lead ECG. AF is classified into five categories based on length of time in the rhythm: paroxysmal, persistent, long-standing persistent, permanent, and nonvalvular. AF is termed paroxysmal when the patient experiences an episode within 7 days that converts back to sinus rhythm. Episode lengths vary but do not continue beyond a week. Persistent AF is experienced as episodes that occur for longer than 7 days. AF sustained for more than 12 months is categorized as long-standing persistent. Permanent AF is defined as patients who remain in AF, and a decision is made not to restore or maintain sinus rhythm by either medical or surgical intervention. Nonvalvular AF occurs in the absence of mitral valve disease or repair.
What interventions are done for patients with A-fib to prevent embolus formation?
- Traditional interventions for AF include antidysrhythmic drugs to slow the ventricular conduction or to convert the AF to normal sinus rhythm (NSR). Examples of drugs to slow conduction are calcium channel blockers such as diltiazem or, for more difficult-to-control AF, amiodarone. Dronedarone is a medication similar to amiodarone, yet better tolerated by patients, for maintenance of sinus rhythm after cardioversion. However, dronedarone should not be used in patients with heart failure because it can cause an exacerbation of cardiac symptoms or with permanent AF because it increases the risk of stroke, myocardial infarction, or cardiovascular death.
- Beta blockers, such as metoprolol and esmolol, may also be used to slow ventricular response. Digoxin is given for patients with heart failure and AF. It is useful in controlling the rate of ventricular response. However, it does not convert AF to sinus rhythm. Carefully monitor the pulse rate of patients taking these drugs.
- Medications used for rhythm control of AF include flecainide, dofetilide, propafenone, and ibutilide. These medications are usually started within the acute care setting because of the risk of developing prolonged QT intervals and bradycardia. Continuous cardiac monitoring and frequent 12-lead ECGs are needed. Amiodarone is also used but does not require an acute care stay. If permanent AF is present, rhythm control antiarrhythmic medications should not be used.
- Although the goal is to convert the patient from AF to SR, that may not be possible for many older adults As such, these patients require long-term anticoagulation to prevent stroke and thrombus formation.
- Because of the unpredictable drug response and many food-drug interactions, laboratory test monitoring (e.g., international normalized ratio [INR]) is required when a patient is taking warfarin. Teach patients the importance of avoiding foods high in vitamin K and to avoid herbs such as ginger, ginseng, goldenseal, Ginkgo biloba, and St. John’s wort, which could interfere with the drug’s action.
- Because of the problems associated with warfarin, direct oral anticoagulants (DOACs) such as dabigatran, rivaroxaban, apixaban, or edoxaban may be given on a long-term basis to prevent strokes associated with nonvalvular AF. Because these drugs achieve a steady state, there is no need for laboratory test monitoring. Prothrombin time (PT) and INR are not accurate predictors of bleeding time when DOACs are used.
- Although the risk of bleeding is lower with DOACs, it is important to be aware of the reversal agents for these medications. Initially, dabigatran was the only DOAC with a reversal agent. Idarucizumab, an intravenous monoclonal antibody, binds to dabigatran, thereby preventing dabigatran from inhibiting thrombin. Side effects of idarucizumab include hypokalemia, confusion, constipation, fever, and pneumonia. Recently, the FDA has approved andexanet alfa as the reversal agent for rivaroxaban and apixaban. However, use of these reversal agents significantly increases the risk of clotting and stroke and should only be used in the event of life-threatening bleeding.
What can embolus formation lead to?
Embolus formation places the patient at high risk for the clot traveling to the brain and causing a stroke.