Clinical Practice Guideline

for

AORTIC INSUFFICIENCY

Developed for the

Aerospace Medical Association

by their constituent organization

American Society of Aerospace Medicine Specialists

 

Overview: This practice guideline primarily addresses aortic insufficiency (AI) (aortic regurgitation) with a normal, three-leaflet aortic valve.  Bicuspid aortic valve is included in the waiver considerations section for completeness; bicuspid aortic valve is discussed in more detail in its own separate practice guideline.  AI, particularly in its milder forms, is usually asymptomatic for decades due to the compensation of the left ventricle to the volume overload produced by this condition.  Symptoms generally do not become clinically apparent until some degree of left ventricular (LV) failure has occurred, usually after the fourth decade of life.  AI is therefore most commonly associated with symptoms related to left ventricular failure, (e.g., exertional dyspnea, orthopnea, fatigue, and paroxysmal nocturnal dyspnea).  Symptoms of angina are rare in the absence of coronary artery disease.  The severity of AI is graded on a 1-4 scale of trace, mild, moderate and severe.  Trace AI is considered to be a physiologically normal variant in the absence of an accompanying AI murmur and with a structurally normal three-leaflet valve.  The natural progression of AI varies based on symptoms and LV dysfunction as listed below.  There is very little published data on the natural history of the progression of AI, particularly the mild to moderate types.  This table reflects outcomes based on preexisting severe AI.

 

Table 1: Natural History of Severe Aortic Insufficiency (Bonow)

Asymptomatic patients with normal LV systolic function

 

  • Progression to symptoms and /or LV dysfunction

<6%/year

  • Progression to asymptomatic LV dysfunction

<3.5%/year

  • Sudden death

<0.2%/year

Asymptomatic patients with LV systolic dysfunction

 

  • Progression to cardiac symptoms

>25%/year

Symptomatic patients

 

  • Mortality rate

>10%/year

 

Although there is a low likelihood of patients developing asymptomatic LV dysfunction, more than one fourth of the patients who die or develop systolic dysfunction will do so prior to the onset of any warning symptoms.

 

In a clinical population, AI is caused by aortic root or leaflet pathology.  Root pathology is most commonly caused by dilatation associated with hypertension and aging.  Other root pathologies include Marfan’s syndrome, aortic dissection, ankylosing spondylitis and syphilis.  Leaflet pathologies include infective endocarditis, bicuspid aortic valve and rheumatic heart disease.  In the aviator population, the most common etiologies will be idiopathic AI with normal aortic valve and root, AI with idiopathic aortic root dilation and bicuspid aortic valve.

 

Theoretical concerns exist that extreme athletic activity or isometric exercise, or activities which include a significant component of such exercise, may promote progression of this condition and should therefore be discouraged.  Examples of such activities would include the anti-G straining maneuver, weight lifting, and sprint running.  Published guidelines for athletes with AI restrict activities for those with the moderate and severe types.  Therefore, moderate AI and asymptomatic severe AI that does not meet guidelines criteria for surgery are restricted to FC IIA.  Symptomatic severe AI and severe AI meeting guidelines criteria for surgery are disqualifying and waiver is not recommended.  Moderate to severe AI should be followed closely, preferably by a cardiologist, for development of criteria for surgical intervention and to address the need for vasodilator therapy.  Medications to reduce afterload, such as ACE inhibitors and nifedipine, have documented clinical benefit in chronic AI, including delaying the need for surgery and improvement of surgical outcome.  The use of approved ACE inhibitors and nifedipine is therefore acceptable in aviators with asymptomatic moderate and severe AI.7 Treatment for AI should always include adequate therapy for hypertension, to decrease afterload.

 

An echocardiogram with Doppler flow study easily diagnoses AI and is the mainstay of severity assessment.  In addition, left ventricular function and chamber size impact the assessment of the severity of disease.

 

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 include: related symptoms such as exertional dyspnea, orthopnea and paroxysmal nocturnal dyspnea.  Also the progression of AI to severe grade and the impact of the anti-G straining maneuver or isometric/dynamic exercise on the degree of AI which could result in reduced cardiac output and hypoperfusion of the brain, and any requirement for medical therapy, such as vasodilators are important concerns for aircrew with AI.

 

Medical Work-up: Work-up for an aviator with aortic insufficiency (or any valvular disease) begins with a detailed description of symptoms, medication usage, activity level along with risk factors for coronary artery disease.  A good cardiac exam is also necessary as well as a recent echocardiogram with its report.  Any other tests results such as Holter monitor tracings, treadmill tests and stress echocardiogram needs to be included in the summary.  Finally a report from the treating cardiologist is required for evaluation.

 

Aeromedical Disposition:

 

Air Force: AFI 48-123 states that any AI greater than trace 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 disqualifying for SMOD personnel (per Chapter 5, retention standards).  The ACS considers trace AI, without the murmur of AI and in the presence of a structurally normal three-leaflet valve, to be a normal variant and therefore qualifying for all classes of flying duties.  ACS review of the echocardiogram is required to confirm that AI is trace and that aortic valve pathology (e.g. bicuspid valve) is not present.  Mild or greater AI is disqualifying for all classes of flying duties and ACS review/evaluation is required for waiver consideration.  ACS evaluation may be required, depending on the flying class or for specific concerns in an individual case.  FC I and IA will only be waiver eligible for mild or less AI; any greater AI is not waiver eligible.  All FC II and FC III personnel require ACS review/evaluation for waiver consideration.  ACS re-evaluations will be performed at 1-3 year intervals, depending on the degree of AI and other related conditions such as chamber dilation, left ventricular function and left ventricular hypertrophy.  As discussed above, the use of approved ACE inhibitors or nifedipine for afterload reduction is acceptable in aviators with asymptomatic moderate or severe AI.  Waiver may be considered after surgery.

 

Army: Though the Army does not fly high G aircraft, it shares the aeromedical concerns of the Air Force regarding aortic insufficiency . It is disqualifying for all aircrew and is discussed in the Army Aeromedical Policy Letter Aortic Regurgitation / Insufficiency.  Normally no exception to policy is recommended for applicants, though this is not an absolute rule.  Rated personnel and other than Class 1 applicants with physiologically insignificant insufficiency will usually be favorably considered for a waiver provided the aircrew member is symptom free and a full cardiac work-up is otherwise negative or demonstrates only minimal cardiac enlargement or structural abnormality.  The minimum cardiovascular work-up must include an aGXT, 24-hr Holter monitor and echocardiogram with Doppler flow study.

 

Navy: Aortic insufficiency associated with a structural abnormality of the valve is considered disqualifying (CD), with no waiver for candidates. Designated individuals can receive waiver recommendations limited to non-high performance aircraft. Traditionally, AI has been felt not to occur in normal subjects, but the Naval Aerospace Medical Institute (NAMI) has detected a limited degree of AI in a number of patients without detectable valvular pathology. On echocardiogram, these "physiologic" AI cases typically have a very small AI jet that does not extend out of the left ventricular outflow tract (LVOT). In these cases, the condition is not considered disqualifying (NCD), and as such does not require a waiver.  All cases of AI must have a full cardiology evaluation including echocardiography. The report must contain quantification of the degree of insufficiency (trivial, mild, moderate, or severe) or alternative criteria measuring the height ratio of the jet to the height of the LVOT in the parasternal long axis view.  The actual echocardiography tape will often be requested by NAMI.

 

Civilian: Airmen who are diagnosed with aortic regurgitation (or insufficiency) are generally followed with yearly echocardiograms for first- and second-class and every other year for third.  Should symptoms begin or cardiac chamber enlargement progress then their cases may be reviewed by a FAA cardiology consultant.  This could lead to a denial of their medical certification. 

 

Waiver Experience:

 

Air Force: AIMWITS search revealed a total of 241 individuals with a submitted aeromedical summary with a diagnosis of aortic insufficiency.  Of that total, there were 33 FC I/IA cases (8 disqualifications), 156 FC II cases (16 disqualifications), 44 FC II cases (5 disqualifications), 1 FC IIU case which was disqualified, 2 ATC cases (with 1 disqualification), and 5 SMOD cases (with 0 disqualifications).  Further breakdown revealed a total of 82 cases without the concurrent diagnosis of BAV.  There were 7 FC I/IA cases (4 disqualifications), 58 FC II cases (6 disqualifications), 13 FC III cases without any disqualifications, and 4 SMOD cases without any disqualifications.  There were no FC IIU or ATC/GBC cases in the non-BAV category.

 

Army: The Aviation Epidemiological Data Repository was sampled from fiscal years 2004-2008 looking at the unique number of pilots per year.  There were 14,800 rated personnel processed during this period.   With regard to Aortic Regurgitation / Insufficiency, there were three waiver granted cases, one waiver continued case and one disqualified case.

 

Navy: Not available at this time.

 

Civilian: The following numbers of airmen are currently issued and being followed with waivers with Aortic Regurgitation: First-class: 415, second-class: 348, and third-class: 1,260.

 

References:

 

AGARD Aerospace Medical Panel Working Group 18. Echocardiographic Findings in NATO pilots: Do Acceleration (+Gz) stresses damage the Heart?  Aviat Space Environ Med, 1997; 68: 596-600.

 

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.

 

Carabello BA.  Progress in Mitral and Aortic Regurgitation.  Current Problems in Cardiology, 2003; 28(10): 549-584.

 

Chung KY, Hardy JC.  Aortic Insufficiency and High Performance Flight in USAF Aircrew, Aerospace Medical Association Program, 67th Annual Scientific meeting, May 1996: A23. 

 

Gray GW, Salisbury DA, Gulino AM.  Echocardiographic and Color Flow Doppler Findings in Military Pilot Applicants.  Aviat Space Environ Med, 1995; 66(1): 32-34.

 

Hardy JC, Pickard JS.  Policy Letter for military Aviators with Aortic Insufficiency, Department of the Air Force, 21 Mar 1996.

 

Kruyer WB.  Cardiology.  In:  Rayman RB, ed. Clinical Aviation Medicine, 4th ed.  New York:  Graduate Medical Publishing, LLC.  2006:  193-196.

 

Willerson JT, Cohn JN, eds.  Cardiovascular Medicine.  Churchill Livingstone Inc., New York, New York.  1995:  191-6.

 

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

 

Zoghbi WA, Enriquez-Sarano M, Foster E, et al.  Recommendations for Evaluation of the Severity of Native Valvular Regurgitation with Two-dimensional and Doppler Echocardiography.  J Amer Society of Echocardiography, 2003; 16: 777-802.

 

Maron BJ and Zipes DP, Co-Chairs.  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.

 

 

 

Prepared by Drs. Bill Kruyer and Dan Van Syoc

 

November 14, 2011