STEPUP Cardiovascular System: Tachyarrhythmias - Atrial Fibrillation

Question 1

What is atrial fibrillation?

Answer 1

Multiple foci in the atria fire continuously in a chaotic pattern, causing a totally irregular, rapid ventricular rate. Instead of intermittently contracting, the atria quiver continuously

Question 2

How fast does the atrial rate become in atrial fibrillation? What about the ventricular rate and why?

Answer 2

1) Atrial rate is over 400 bpm

2) Most impulses are blocked at the AV node so ventricular rate rangers between 75 and 175

Question 3

What are patients with AFib and underlying heart disease at a markedly increased risk for?

Answer 3

Adverse events, such as thromboembolism and hemodynamic compromise

Question 4

What are causes of atrial fibrillation?

Answer 4

1) Heart disease: CAD, MI, HTN, mitral valve disease
2) Pericarditis and pericardial trauma (e.g., surgery)
3) Pulmonary disease, including PE
4) Hyperthyroidism or hypothyroidism
5) Systemic illness (e.g., sepsis, malignancy, DM)
6) Stress (e.g., postoperative)
7) Excessive alcohol intake (“holiday heart syndrome”)
8) Sick sinus syndrome
9) Pheochromocytoma

Question 5

What are clinical features of AFib?

Answer 5

1) Fatigue and exertional dyspnea
2) Palpitations, dizziness, angina, or syncope may be seen
3) An irregularly irregular pulse
4) Blood stasis (secondary to ineffective contraction) leads to formation of intramural thrombi, which can embolize to the brain

Question 6

What are the three main goals of treating AFib and atrial flutter?

Answer 6

1) Control ventricular rate
2) Restore normal sinus rhythm
3) Assess need for anticoagulation

Question 7

How is AFib diagnosed and what is found on this test?

Answer 7

ECG findings: Irregularly irregular rhythm (irregular RR intervals and excessively rapid series of tiny, erratic spikes on ECG with a wavy baseline and no identifiable P waves)

Question 8

What are the three states of AFib that determine treatment in a patient?

Answer 8

1) Acute AFib in a hemodynamically unstable patient
2) Acute AFib in a hemodynamically stable patient
3) Chronic AFib

Question 9

How do you treat acute AFib in a hemodynamically unstable patient?

Answer 9

Immediate electrical cardioversion to sinus rhythm

Question 10

How do you treat acute AFib in a hemodynamically stable patient?

Answer 10

1) Rate control
2) Cardioversion to sinus rhythm (after rate control is achieved)
3) Anticoagulation to prevent embolic cerebrovascular accident (CVA)

Question 11

What should you do before controlling rate in a patient with acute AFib in a hemodynamically stable patient? What medical treatment may be used for rate control of AFib? What if ventricular systolic dysfunction is present?

Answer 11

1) Determine the pulse in a patient with AFib. If it is too rapid, it must be treated. Target rate is 60 to 100 bpm.
2) Beta-blockers are preferred. Calcium channel blockers are an alternative
3) If ventricular systolic dysfunction is present, consider digoxin or amiodarone (useful for rhythm control)

Question 12

Which patients are candidates for cardioversion in the setting of AFib? Is electrical or pharmacologic cardioversion preferable in patients who have rate control achieved? When should you use pharmacologic cardioversion?

Answer 12

1) Candidates for cardioversion include those who are hemodynamically unstable, those with worsening symptoms, and those who are having their first ever case of AFib
2) Electrical cardioversion is preferred over pharmacologic cardioversion. Attempts should be made to control ventricular rate before attempting DC cardioversion
3) Use pharmacologic cardioversion only if electrical cardioversion fails or is not feasible: Parenteral ibutilide, procainamide, flecainide, sotalol, or amiodarone are choices

Question 13

After 48 hours of having AFib (or unknown period of time), what happens to the risk of embolization during cardioversion? What should you therefore do for these patients?

Answer 13

1) If AFib present >48 hours (or unknown period of time), risk of embolization during cardioversion is significant (2% to 5%)
2) Anticoagulate patients for 3 weeks before and 4 weeks after cardioversion

Question 14

What is a goal anticoagulation range of INR for patients receiving anticoagulation for AFib?

Answer 14

An INR of 2 to 3 is the anticoagulation goal range

Question 15

To avoid waiting 3 weeks for anticoagulation before cardioversion, what can you do for a patient with AFib > 48 hours (or unknown period of time)? What will this test tell you? What do patients still require if they have AFib > 48 hours (or unknown period of time) and do undergo cardioversion?

Answer 15

1) Obtain a transesophageal echocardiogram (TEE) to image the left atrium (LA)
2) If no thrombus is present, start IV heparin and perform cardioversion within 24 hours
3) Patients still require 4 weeks of anticoagulation after cardioversion

Question 16

In patients with chronic AFib, how should you control the rate? When is anticoagulation used in the setting of chronic AFib?

Answer 16

1) Rate control with beta-blocker or calcium channel blocker
2) Patients with “lone” AFib (i.e., AFib in the absence of underlying heart disease or other cardiovascular risk factors) under age 60 do not require anticoagulation because they are at low risk for embolization (aspirin may be appropriate)
3) Treat all other patients with chronic anticoagulation (warfarin)

Question 17

What is cardioversion? What is the purpose of cardioversion? Why do you avoid a shock on the T wave? What are indications for cardioversion?

Answer 17

1) Delivery of a shock that is in synchrony with the QRS complex
2) Purpose is to terminate certain dysrhythmias such as PSVT or VT
3) An electric shock during T wave can cause Vfib, so the shock is timed not to hit the T wave
4) Indications: AFib, atrial flutter, VT with a pulse, SVT

Question 18

What is defibrillation? What is the purpose of defibrillation? What are indications for defibrillation?

Answer 18

1) Delivery of a shock that is not in synchrony with the QRS complex
2) Purpose is to convert a dysrhythmia to normal sinus rhythm
3) Indications: VFib, VT without a pulse

Question 19

What is an automatic implantable defibrillator? What are indications for an automatic implantable defibrillator?

Answer 19

1) Device that is surgically placed: When it detects a lethal dysrhythmia, it delivers an electric shock to defibrillate. It delivers a set number of shocks until the dysrhythmia is terminated
2) Indications: VFib and/or VT that is not controlled by medical therapy

Question 20

What did the AFFIRM trial show?

Answer 20

The AFFIRM trial showed that rate control is superior to rhythm control in treatment of AFib

Question 21

What is the risk of CVA per year in patients with lone AFib? With AFib and heart disease?

Answer 21

1) Patients with “lone AFib”: 1%/year

2) Patients with heart disease: 4%/year