Clinical Practice Guideline

for

AORTIC STENOSIS

Developed for the

Aerospace Medical Association

by their constituent organization

American Society of Aerospace Medicine Specialists

 

Overview: Aortic stenosis (AS) usually occurs at the level of the aortic valve.  Supravalvular and subvalvular forms of AS exist but are unusual congenital defects unlikely to present as a new diagnosis in an adult military aviator/aircrew.  These would be addressed aeromedically on a case-by-case basis.  Valvular AS has several causes.  In older adults the most common is senile AS, an aging-related calcifying, degenerative process.  In the military aviator/aircrew population the most common cause will be associated bicuspid aortic valve.  AS is still unusual in military aviator/aircrew with bicuspid aortic valve because this complication usually occurs in middle-aged or older patients.

 

While the diagnosis may be suspected by careful auscultation, AS is primarily an echocardiographic (echo) diagnosis.  On echo AS is graded by a combination of mean pressure gradient across the stenotic valve and calculated valve area.  Grading categories are mild, mild-to-moderate, moderate and severe.

 

In early 2007, the American Heart Association published new infective endocarditis guidelines that are dramatically different from past recommendations.  Subsequently 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 mitral regurgitation) and uncorrected small defects of the atrial and ventricular septum.

 

Aeromedical Concerns: Aeromedical concerns for AS include progression to significant stenosis and requirement for aortic valve replacement or repair.  The prognosis of mild AS is good and essentially normal for at least five years after diagnosis.  Once AS has progressed to moderate or severe, aeromedical and clinical concerns also include sudden cardiac death, syncope, angina and dyspnea.  Angina may occur in the absence of significant coronary atherosclerosis while dyspnea may appear as a result of left ventricular dysfunction.  Event rates are 5% and 10% per year for asymptomatic and symptomatic moderate AS, respectively.  Event rates are considerably higher for severe AS.  Mild-to-moderate AS has normal expected event rates for 1-3 years, but represents AS that is likely progressing toward moderate and later severe AS.  At this level of stenosis, maintenance of normal cardiac output under +Gz load is a potential aeromedical concern, prompting restriction from high performance military flying duties.

 

Medical Work-up: Evaluation of an aviator with the diagnosis of aortic stenosis requires a complete history to include a detailed description of all symptoms, medications and activity level, as well as all cardiac risk factors (positive and negative).  Documentation by a cardiologist or internist of physical exam findings is also required.  Also required is a copy of the echo and any other cardiac tests performed.

 

Aeromedical Disposition:

 

Air Force: AFI 48-123 states that any degree of valvular stenosis is disqualifying for all flying classes.  For FC IIU and ATC/GBC personnel, symptomatic valvular heart disease is disqualifying as is asymptomatic valvular disease graded moderate or worse.  Aortic disease (or any valvular disease) is not listed as disqualifying for SMOD personnel.

 

Initially, waiver will typically be valid for one year with ACS re-evaluation required for waiver renewal consideration.  If AS is mild and appears stable after several ACS evaluations, waiver renewal may be extended to two to three years upon recommendation by the ACS.  Waiver for mild-to-moderate AS will be valid for only one year. 

 

Army: Aortic Stenosis (AS) is disqualifying for Army pilots for accession and retention.  The concerns of the Army are similar to those of the Air Force, primarily increased risk for syncope and sudden death in more advanced cases.  Normally applicants are not granted a waiver to enter flight training.  For rated aviators, mild AS, (gradients below 20mm Hg) will generally be granted a waiver. Moderate AS may be considered for waiver provided complete cardiology evaluation is negative. AS with syncope, or other symptom complex are concerning for continued duties and considered less favorable for waiver action. Surgery is also considered disqualifying and generally no waiver is recommended in those cases, though select cases are reviewed individually.  The evaluation for waiver consideration consists of a complete cardiology evaluation to include an aGXT, 24-hour Holter Monitor, and Echocardiogram with Doppler flow study.

 

Navy: Any degree of aortic stenosis is considered disqualifying (CD) for all aviation classes.

Waivers to flight status may be considered only for designated individuals with mild AS (pressure

gradient < 25 mm Hg). They are restricted to non-ejection seat aircraft, maritime/helo/ transport

only.  Applicants with AS are not typically encountered, but will not be considered for waiver. 

Information required for waiver includes:   

1. A full cardiology evaluation with echocardiogram. 

2. The echo report must include quantization of the degree of stenosis.  Severe AS is generally

defined as a valve area less than or equal to (0.7-0.8) cm2/M2 BSA and/or left

ventricular outflow tract (LVOT):aorta pressure gradient of greater than or equal to 50 mm Hg).

3. Maximal pressure gradients are a function of both valve area and myocardial performance.

Therefore, determination of the degree of AS based solely on gradients may be misleading, and

must factor in the state of the myocardium.

 

Civilian: Airmen with aortic stenosis and bicuspid aortic valve are followed yearly with echocardiograms.  When the mean gradient across the valve reaches 40 mm mercury, or the valve area is less than or equal to 1.0 cm2 the airman will be denied. Granting of certification will likely require review by a FAA cardiology consultant.  Symptoms of aortic valve stenosis will result in denial.  The FAA allows medical certification for valve replacement.  It requires an authorization for special issuance.  There is a mandatory 6 month observation period prior to consideration for waiver.  The airman will  need to provide the initial echocardiogram report prior to the surgery, the hospital admission and discharge summaries, cardiac catheterization report if performed, operative report, and pathology report of valve. Also required will be a current cardiovascular status, current echocardiogram, lipid panel and fasting blood sugar.  If a mechanical valve is inserted, the airman will need to provide the International Normalized Ratio (INR) levels.  The FAA requires 80% of these values to be between 2.5 and 3.5.  The Ross Procedure is acceptable. This is when the aortic valve is replaced with the individual's own pulmonary valve and a prosthetic valve is inserted in the pulmonary valve position. The airman will not require anticoagulation if this is done.  All first- and second-class airmen must have their cases reviewed by a FAA Cardiology consultant.  For the initial certification of these airmen they are also required to provide the results of a maximal nuclear stress test for first- and second-class and a plain Bruce protocol for third-class.  24 hour Holter monitoring may be also required. 

 

Waiver Experience:

 

Air Force: AIMWITS search revealed a total of 17 individuals with a submitted aeromedical summary for the diagnosis of AS.  There were 9 FC II cases, six FC III cases and 1 FC IIU case.  A total of 7 received a disqualification disposition: 4 were FC II, 2 were FC III and the one FC IIU case was also disqualified.  All disqualified cases had either advanced AS or AI or a combination of both.

 

Army: Aortic stenosis has been an uncommon diagnosis among rated Army aviators.  Between 2009 and 2011 there was an average aviator population of 14919 as identified by having an annual flight physical.  During this time, there were no cases of aortic stenosis in the population. However, during the 17 year period between 1988 and 2015 there were 30 cases identified, of which 15 had been granted waiver.

 

Navy: Not available at this time

 

Civilian: All the aortic valve conditions are combined in one group. As of December 2011 there were 340 first-class, 245 second-class and 1,220 third-class airmen issued. 

 

ICD 9 codes for Aortic Stenosis

424.10

Aortic valve disorders

395.0

Rheumatic aortic stenosis

396.0

Mitral valve stenosis & aortic valve stenosis

 

References:

 

Bonow RO, Cheitlin MD, Crawford MH, Douglas PS.  36th Bethesda conference: Eligibility recommendations for competitive athletes with cardiovascular abnormalities.  Task force 3: Valvular heart disease.  J Am Coll Cardiol, 2005; 45(8): 1334-40.

 

Bonow RO, chair.  ACC/AHA 2006 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.  J Am Coll Cardiol.  2006; 48(3): e1-e148.

 

Kruyer WB.  Cardiology.  In: Rayman RB, ed. Clinical Aviation Medicine, 4th ed.  New York: Graduate Medical Publishing, LLC.  2006; 189-92

 

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.

 

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

 

 

 

 

Prepared by Drs. Dan Van Syoc and William Kruyer

May 21, 2012