Review Question - QID 106829

Atrial fibrillation (Figure E) will cause hemodynamic compromise in patients with aortic stenosis (AS) due to reduced left ventricular preload.

Aortic stenosis (AS) is the most common valvular disease in the world and occurs when the aortic valve becomes narrowed. It is commonly caused by age-related calcification of the valve leaflets and presents when patients are in their 60's or 70's. It produces a characteristic crescendo-decrescendo systolic murmur preceded by an ejection click. Patients with AS are highly preload dependent. Thus, a loss in atrial contraction, as occurs in atrial fibrillation (Figure E), will cause a drop in cardiac output that results in hemodynamic compromise due to reduced LV preload. Aortic valve replacement is the treatment of choice for symptomatic patients.

Grimard & Larson review the diagnosis and management of AS. They state that as the disease worsens, compensatory mechanisms of the heart become inadequate, leading to symptoms of heart failure, angina, or syncope. Aortic valve replacement should be recommended in most patients with any of these symptoms accompanied by evidence of significant AS on echocardiography. Watchful waiting is recommended for most asymptomatic patients, including those with hemodynamically significant AS.

Gutierrez & Blanchard review the diagnosis and management of atrial fibrillation. They state that treatment issues include deciding when to restore normal sinus rhythm, when to control rate only, and how to prevent thromboembolism. Rate control is the preferred management option in most patients. Rhythm control is an option for patients in whom rate control cannot be achieved or who have persistent symptoms despite rate control. The current recommendation for strict rate control is a resting heart rate of less than 80 beats per minute.

Figures are described in the incorrect answer key below.

Incorrect Answers:
Answer 1: Figure A is an EKG demonstrating normal sinus rhythm. This would not decrease preload nor cause hemodynamic compromise in AS.
Answer 2: Figure B is an EKG demonstrating 2nd degree AV block - Mobitz type 1. Note the progressive lengthening of the PR interval until a beat is dropped. This rhythm is usually asymptomatic and would not commonly cause hemodynamic compromise in AS.
Answer 3: Figure C is an EKG demonstrating Wolf-Parkinson-White (WPW) syndrome. Note the delta wave at the beginning of each QRS complex caused by an abnormal accessory electrical conduction pathway. WPW on its own would not cause hemodynamic compromise in a patient with AS.
Answer 4: Figure D is an EKG demonstrating normal sinus rhythm with occasional monomorphic premature ventricular contractions (PVCs). PVCs would not cause hemodynamic compromise in a patient with AS.