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.
What are nonsurgical management interventions that can be done for a patient with A-fib?
Nonsurgical interventions most commonly include electrical cardioversion, left atrial appendage closure, radiofrequency catheter ablation, and pacing.
Electrical cardioversion as an intervention for A-fib… What is it?
- Electrical cardioversion is a synchronized countershock that may be performed to restore normal conduction in a hospitalized patient with new-onset AF. A cardioversion can also be scheduled electively for stable AF that is resistant to medical therapy. When the onset of AF is greater than 48 hours, the patient must take anticoagulants for at least 3 weeks (or until the INR is 2 to 3) before the procedure to prevent clots from moving from the heart to the brain or lungs. If the onset of AF is uncertain, a transesophageal echocardiogram (TEE) may be performed to assess for clot formation in the left atrium.
- The shock depolarizes a large amount of myocardium during the cardiac depolarization. It is intended to stop the re-entry circuit and allow the sinus node to regain control of the heart. Emergency equipment must be available during the procedure. The physician, advanced practice nurse, or other qualified nurse explains the procedure to the patient and family. Help the patient sign a consent form unless the procedure is an emergency for a life-threatening dysrhythmia. Because he or she is usually conscious, a short-acting anesthetic agent is administered for sedation.
- One electrode is placed to the left of the precordium, and the other is placed on the right next to the sternum and below the clavicle. The defibrillator should be set in the synchronized mode. A dot or line will be indicated over each QRS complex, confirming the synchronized mode. This avoids discharging the shock during the T wave, which may increase ventricular irritability, causing ventricular fibrillation (VF). Charge the defibrillator to the energy level requested, usually starting at a low rate of 120 to 200 joules for biphasic machines.
- After cardioversion, assess the patient’s response and heart rhythm. Therapy is repeated, if necessary, until the desired result is obtained or alternative therapies are considered. If the patient’s condition deteriorates into VF after cardioversion, check to see that the synchronizer is turned off so immediate defibrillation can be administered.
What is included in nursing care after cardioversion?
- Maintaining a patent airway
- Administering oxygen
- Assessing vital signs and the level of consciousness
- Administering antidysrhythmic drug therapy, as prescribed
- Monitoring for dysrhythmias
- Assessing for chest burns from electrodes
- Providing emotional support
- Documenting the results of cardioversion
Left atrial appendage closure as an intervention for A-fib… What is it?
Left atrial appendage closure. For patients who are at high risk for stroke and who are not candidates for long-term anticoagulation, the left atrial appendage (LAA) occlusion device may be an option. The LAA is a small sac in the wall of the left atrium. For those with nonvalvular AF, the LAA is the most common site of blood clot development leading to the risk of stroke. Inserted percutaneously via the femoral vein, a device to occlude the LAA is delivered via a transseptal puncture. In the United States, the Watchman (nitinol frame with fenestrated fabric) is the only device approved for use in atrial fibrillation patients. After insertion, anticoagulation with aspirin and warfarin is required. A repeat TEE is performed approximately 45 days after insertion to assess for leaks around the device. If no leak is detected, the warfarin is stopped and antiplatelet therapy is continued. Complications are similar to those for undergoing cardiac ablation procedure.
Radiofrequency catheter ablation as an A-fib intervention… What is it?
Radiofrequency catheter ablation (RCA) is an invasive procedure that may be used to destroy an irritable focus in atrial or ventricular conduction. The patient must first undergo electrophysiologic studies and mapping procedures to locate the focus. Then radiofrequency waves are delivered to abolish the irritable focus. When ablation is performed in the AV nodal or His bundle area, damage may also occur to the normal conduction system, causing heart blocks and requiring implantation of a permanent pacemaker.
In AF, pulmonary vein isolation and ablation create scar tissue that blocks impulses and disconnects the pathway of the abnormal rhythm. Patients with AF with a rapid ventricular rate not responsive to drug therapy may have AV nodal ablation performed to totally disconnect the conduction from the atria to the ventricles, which requires implantation of a permanent pacemaker. AF ablation should not be performed if long-term anticoagulation is contraindicated.
Biventricular pacing as an A-fib intervention… What is it?
Biventricular pacing. This type of pacing may be another alternative for patients with heart failure and conduction disorders. Biatrial pacing, antitachycardia pacing, and implantable atrial defibrillators are other methods used to suppress or resolve AF.
What is a surgical intervention for a patient with A-fib?
The MAZE procedure
What is the MAZE procedure?
- Patients in AF with heart failure may benefit from the surgicalmaze procedure, an open-chest surgical technique often performed with coronary artery bypass grafting (CABG). Before this procedure, electrophysiologic mapping studies are done to confirm the diagnosis of AF. The surgeon places a maze of sutures in strategic places in the atrial myocardium, pulmonary artery, and possibly the superior vena cava to prevent electrical circuits from developing and continuing AF. Sinus impulses can then depolarize the atria before reaching the AV node and preserve the atrial kick. Postoperative care is similar to that after other open-heart surgical procedures.
- The surgical MAZE procedure is being replaced by catheter procedures using a minimally invasive form. The catheter maze procedure is done by inserting a catheter through a leg vein into the atria and dragging a heated ablating catheter along the atria to create lines (scars) of conduction block. Patients having this minimally invasive form of the procedure have fewer complications, less pain, and a quicker recovery than those with the open, surgical maze procedure.
What are some home care points the patient with A-fib be made aware of?
- Patients discharged from the hospital may have considerable needs, often more related to their underlying chronic diseases than to their dysrhythmia. A case manager or care coordinator can assess the need for health care resources and coordinate access to services.
- The focus of home care is often nursing assessment and health teaching. The community-based nurse provides the patient and family members with an opportunity to verbalize their concerns and fears. Provide emotional support and referrals for ongoing care in the community. Assess the patient for possible side effects of antidysrhythmic agents or anticoagulation therapy.
