questions 8

Atrial Fibrillation

Topic updated on 10/15/17 9:50pm

  • A 68-year-old male presents with palpitations, lightheadedness, and weakness. These symptoms appear to worsen with increased alcohol intake. Medical history is significant for hypertension being treated with hydrochlorothiazide. On physical exam, the patient appears uncomfortable. There is an irregularly irregular pulse when palpating the radial artery. On cardiac auscultation, the first heart sound (S1) is of variable intensity. There is mild bibasilar crackles on pulmonary auscultation and an absence of peripheral edema.  An electrocardiagram is obtained.
  • A supraventricular tachyarrhythmia secondary to uncoordinated atrial contractions
    • results in an irregularly irregular rhythm
      • non-repetitive pattern in the RR interval
    • may reduce cardiac output
    • may result in thrombus formation in the atrium
    • most common site of origin for ectopic foci is pulmonary veins
  • Pathogenesis
    • usually due to an underlying cause 
      • e.g., atrial enlargement and inflammation or infiltrative disease affecting the atrium
  • Causes include
    • structural abnormalities
      • e.g., left atrial enlargement, mitral and aortic stenosis, mitral and aortic regurgitation, and malignancy
    • conduction abnormalities
      • e.g., Wolff-Parkinson-White (WPW) syndrome
    • medications
      • theophylline and digoxin
    • cardiac functional abnormalities
      • e.g., myocardial infacrtion, pulmonary embolism, and coronary artery disease
    • hyperthyroidism
    • electrolyte disturbances
      • e.g., hypomagnesemia and hypokalemia
    • cardiomyopathies
      • e.g., dilated and hypertrophic cardiomyopathy
    • alcohol abuse ("holiday heart syndrome")
    • post-operatively after heart surgery
      • especially after coronary artery bypass grafting (CABG)
  • Epidemiology
    • most common arrhythmia
  • Symptoms
    • asymptomatic
    • in symptomatic cases
      • palpitations
      • shortness of breath (suggesting heart failure)
      • lightheadedness
  • Physical exam
    • irregularly irregular pulse
    • focal neurological deficit if this results in an embolic stroke
    • in cases of atrial fibrillation leading to heart failure
      • elevated jugular venous pulse (JVP)
      • bibasilar rales on pulmonary auscultation
      • peripheral edema
  • Electrocardiogram (EKG or ECG) 
    • irregularly irregular rhythm
    • absent P waves
    • if arrhythmia is not captured on ECG then
      • Holter monitoring in the outpatient setting
        • these patients are hemodynamically stable
      • telemitry in the inpatient setting
  • Transthoracic echocardiogram (TTE)
    • can assess atrial size and ventricular function, thickness, and size
    • can also assess for valvular and pericardial disease, and peak right ventricular pressure
    • transesophageal echocardiogram (TEE) is more sensitive in detecting thrombi in the left atrium
  • Laboratory testing
    • thyroid stimulating hormone (TSH) and free T4 level
    • electrolyte level
  • Multifocal atrial tachycardia (MAT)
    • commonly seen in patients with pulmonary disease
      • e.g., chronic obstructive pulmonary disease (COPD)
  • Premature atrial contractions (PACs)
  • Atrial flutter
  • Wolff-Parkinson-White syndrome
  • Hemodynamically unstable patients
    • synchronized cardioversion
  • Hemodynamically stable patients
    • slowing of the ventricular rate
      • patients with new onset atrial fibrillation become symptomatic due to rapid ventricular response (except in cases of stroke)
      • intravenous β-blockers or nondihydropyridine calcium channel blocker
    • long-term management
      • rate control (preferred)
        • β-blocker or nondihydropyridine calcium channel blocker
        • digoxin if the patient is hypotensive 
      • rhythm control
        • antiarrhythmics
          • depends on patient's comorbidities
      • anticoagulation
        • in order to decrease the risk of thromboembolism
        • stroke risk stratification CHA2DS2-VASc score
          • Congestive heart failure = 1 point
          • Hypertension = 1 point
          • Age (75 years or older) = 2 points
          • Diabetes = 1 point
          • Stroke/transient ischemic attack/thromboembolism = 2 point
          • Vascular disease = 1 point
            • e.g., previous myocardial infarction and peripheral artery disease
          • Age (65 - 74 years) = 1 point
          • Sex category (female) = 1 point
        • score of 0 or 1 use
          • aspirin
          • conservative monitoring
        • score of 2 or more use oral anticoagulation
          • dabigatran
          • rivaroxaban
          • apixaban
            • novel anticoagulants contraindicated in renal failure
          • warfarin  
            • international normalized ratio (INR) target of 2-3
            • only warfarin should be used with vascular lesions (eg. mechanical valves)
Prognosis, Prevention, and Complications
  • Prognosis
    • increased risk of stroke
  • Complications
    • atrial mural thrombi emboli to cerebral vessels
      • can cause ischemic stroke and transient ischemic attack
    • atrial thrombus to common iliac artery
      • requires immediate embolectomy to remove occlusion and preserve limb 


Qbank (3 Questions)

(M3.CV.20) A 78-year-old man presents to the emergency room with a three day history of palpitations. He denies dizziness, dyspnea, and chest pain, and says he sleeps comfortably on one pillow each night. His history is significant for diabetes mellitus type 2, hyperlipidemia, and hypertension. Medications include glyburide, lisinopril, and hydrochlorothiazide. The patient has a ten pack-year history of smoking but quit 15 years ago. He does not drink alcohol or use drugs. His heart rate is 115/min and his blood pressure is 145/95 mmHg. Physical examination demonstrates no evidence of heart failure. Electrocardiogram shows atrial fibrillation with rapid ventricular response. Which of the following is an appropriate therapy for this patient: Topic Review Topic

1. Metoprolol and aspirin
2. Metoprolol and warfarin
3. Digoxin and aspirin
4. Digoxin and warfarin
5. Diltiazem and aspirin

(M3.CV.205) A 59-year-old woman presents to the ED with palpitations, which she has never experienced before now. Her past medical history is notable for chronic obstructive pulmonary disease (COPD) for which she has been hospitalized once in the last year. On exam her T 98.4F, HR 86, BP 105/70, RR 18, SpO2 94% on room air consistent with her baseline. Her EKG is shown in Figure A. What is the most common site of origin for ectopic foci causing the arrhythmia in this patient? Topic Review Topic
FIGURES: A          

1. Tricuspid valve
2. Bicuspid valve
3. Pulmonary veins
4. Right ventricle
5. Left ventricle

(M2.CV.59) A 76-year-old male with a 5 year history of atrial fibrillation presents to the Emergency Department with an inability to move his left leg. The patient notes that he first noted that his leg "felt funny" about two hours ago, and that it appeared to be more pale than normal. Since the leg started feeling funny, his ability to move it has decreased, to the point where he can no longer move it. He recently ran out of his warfarin, and hasn't taken any in two weeks. On physical exam his vital signs are within normal limits. His neurological exam reveals a pale, painful left leg with absent femoral and dorsalis pedis pulses. He has no other strength deficits and pulses in his right leg and right arm are intact. Which of the following would be the appropriate first action for this patient's condition? Topic Review Topic

1. Thrombolysis
2. Embolectomy
3. Fasciotomy
4. Amputation
5. No intervention necessary

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