Clinical Practice Guideline

for

BICUSPID AORTIC VALVE

Developed for the

Aerospace Medical Association

by their constituent organization

American Society of Aerospace Medicine Specialists

 

Overview: Bicuspid aortic valve (BAV) occurs in 1-2% of the general U.S. population and is the most common congenital cardiac malformation, excluding mitral valve prolapse.  The prevalence of BAV has been about 0.6% in the United States Air Force (USAF) database of Medical Flight Screening echocardiograms (echo) performed on pilot training candidates.  Over 70% of BAV subjects will develop some degree of aortic stenosis (AS) and/or aortic insufficiency (AI) during their lifetime.  Additionally, 30-40% will require surgical placement of a prosthetic aortic valve during their lifetime, predominantly after the age of 45 years.

 

In early 2007, the American Heart Association published new infective endocarditis guidelines that are dramatically different from past recommendations.  Endocarditis prophylaxis was recommended only for specified high risk groups, and only for dental procedures, respiratory tract procedures, and procedures on infected skin, skin structures or musculoskeletal tissue.  The high risk group was limited to prosthetic cardiac valves, previous endocarditis, select congenital heart conditions and cardiac transplant patients with valvulopathy.  Prophylaxis was no longer recommended for gastrointestinal or genitourinary procedures.  Conditions commonly seen by most aerospace medicine practitioners were not included in the list of high risk conditions.  Such common conditions no longer recommended for endocarditis prophylaxis include, but are not limited to, mitral valve prolapse, bicuspid aortic valve, mitral or aortic regurgitation with normal valve (e.g. primary MR) and uncorrected small defects of the atrial and ventricular septum.

 

Aeromedical Concerns: Concerns: Aeromedical concerns include development and progression of AS and/or AI and the risk of infective endocarditis.  Risk of a sudden incapacitating event is very low and aeromedically acceptable in the absence of significant AS or severe AI.  Waiver policies are thus primarily dependent on the presence and severity of associated AS and AI.  AI severity is graded by echo as:  trace, mild, moderate and severe.  AS severity is graded by echo as: mild, mild-to-moderate, moderate and severe.

 

Medications to reduce afterload, such as ACE inhibitors, have documented clinical benefit in chronic AI, including delaying the need for surgery and improvement of surgical outcome.  The use of approved ACE inhibitors is therefore acceptable in aviators with asymptomatic moderate and severe AI (check with approval authority for specifics).

 

Medical Work-up: A complete history and physical examination is mandatory to include detailed description of symptoms, medications, activity level and all CAD risk factors (positive and negative).  A copy of the local echo report and videotape or CD copy of the echo documenting BAV need to be reviewed by approval authority specialists.  Also important are copies of reports and tracings of any other cardiac tests performed locally for clinical assessment (e.g. Holter, treadmill, stress echocardiogram).  Depending on the approval authority and specifics of the case, additional local cardiac testing is may be required.

 

Aeromedical Disposition:

 

Air Force: BAV is disqualifying for all classes of flying duties.  In the US Air Force, review or evaluation is required at the Aeromedical Consultation Service for waiver consideration.  As stated above, waiver recommendations are primarily dependent on the presence and severity of associated AS and AI. 

FC I and IA will only be waived for BAV with ≤ mild AI and no AS; any greater AI or AS is not waiverable.  FC II requires ACS evaluation for waiver consideration.  FC III with trace or no AI and with no AS may receive a waiver recommendation after ACS review; formal ACS evaluation will be requested if there is mild or worse AI or any degree of AS.  Other specific concerns about an individual case may require ACS evaluation.  If the disease process appears mild and stable, waiver for all classes of flying duties will generally be valid for three years with ACS reevaluation/review at that time for waiver renewal.

 

Army: Bicuspid aortic valve is not disqualifying in Army Regulation 40-501 Standards of Medical Fitness, unless there is associated tachyarrhythmia, mitral regurgitation, aortic stenosis, insufficiency, or cardiomegaly.  Army aeromedical policy letter, (APL) discussion of bicuspid aortic valve articulates the concern that bicuspid aortic valves become stenotic two-thirds to three-fourths of the time; with increasing age being the major risk factor.  Pilot applicants are considered for waiver on a case by case basis, but are usually granted waivers with normal cardiac function.  Rated and non-rated Army aviators with bicuspid aortic valves and no other associated findings are considered qualified and the condition recorded for information only.  Waiver continuation requires submission of a cardiology evaluation to include echocardiogram with Doppler flow study every 5 years.

 

Navy: Because congenital bicuspid aortic valves can degenerate and progress to aortic stenosis or insufficiency, a bicuspid aortic valve is CD. Waivers will not be considered for applicants. If an incidental finding in designated aircrew, condition may be waiverable with possible restriction on aircraft or flight profile.

 

Civilian: There is no requirement in the U.S. Civil sector to perform echocardiography on each airman so unless the airman has a murmur that is detected on examination or ends up having an echocardiogram performed the FAA would not know.  If an airman is discovered to have a bicuspid aortic valve, they are generally followed using the special issuance process with status reports and echocardiograms.  For aortic stenosis an airman is disqualified should they develop a gradient across the valve of 40 mm or the valve area becomes less than 1 cm2. Aortic insufficiency is also followed with similar requirements and should the airman develop other problems such as significant chamber enlargement or atrial fibrillation.

 

Waiver Experience:

 

Air Force: Review of AIMWTS showed 144 cases of BAV; 44 FC I/IA, 76 FC II and 24 FC III.  The aeromedical summaries (60) for all disqualified (16) and 44 randomly selected cases were reviewed.  Of the 16 BAV cases disqualified, three were FC I/IA, nine FC II and four FC III.  Of the 16 BAV cases disqualified, eight were disqualified for BAV and associated cardiac conditions (e.g. moderate to severe AI, dilated aortic root, status post aortic valve replacement due to AI), three for additional cardiac conditions (e.g. coronary artery disease, exercise-induced syncope) and the remaining five for other medical conditions.

 

Army: The Aeromedical Epidemiological Data Repository (AEDR) catalogs all Army flight physicals since 1960.  There have been approximately 160,000 individual aircrew entered in this database.  During this period of time, there have been 76 cases of bicuspid aortic valve discovered, primarily in applicants.  Of those, 51 were retained in aviation.

 

Navy: Not available at this time

 

Civilian: Statistical data on numbers of bicuspid aortic valve are not kept. 

 

 

References:

 

Kruyer WB. Cardiology. In: Rayman RB, ed. Clinical Aviation Medicine, 3rd ed. New York: Graduate Medical Publishing, LLC, 2000; 180-88.

 

Kruyer WB, Gray GW, Leding CJ. Clinical aerospace cardiovascular medicine. In: DeHart RL, Davis JR eds. Fundamentals of Aerospace Medicine, 3rd ed. Philadelphia: Lippincott Williams & Wilkins, 2002; 348-49 and 352.

 

Bonow RO, chair. ACC/AHA guidelines for the management of patients with valvular heart disease. A report of the American College of Cardiology/American Heart Association task force on practice guidelines (committee on management of patients with valvular heart disease).  J Am Coll Cardiol.  32(5):  1486-588, Nov 1998.

 

Cheitlin MD, Douglas PS, Parmley WW. 26th Bethesda conference: Recommendations for determining eligibility for competition in athletes with cardiovascular abnormalities. Task force 2: Acquired valvular heart disease.  J Am Coll Cardiol.  24(4):  874-80, Oct 1994.

 

Wilson W, chair.  Prevention of infective endocarditis: Guidelines from the American Heart Association.  Circulation.  2007; 115:  1-19.

 

 

Prepared by Drs. Bill Kruyer and Dan Van Syoc

11/10/10