Efficacy of echocardiographic screening of pilot applicants.

BACKGROUND: The efficacy of cardiac screening programs for individuals in competitive athletics and high-risk occupations such as commercial and military aviation continues to be highly debated. For the past 12 yr, all United States Air Force (USAF) pilot applicants have undergone screening echocardiography. METHODS: All available studies were reviewed for disqualifying (DQ) diagnoses. Findings were analyzed and compared to current USAF waiver policy. RESULTS: Between inception in March 1994 and 01 September 2006, there were 20,208 screening echocardiograms performed. Of these, 294 (1.45%) were initially read as disqualifying. The most common diagnoses were bicuspid aortic valves with mild or less aortic insufficiency (N = 154, 0.76%), mitral valve prolapse with mild or less mitral regurgitation (N = 51, 0.25%), and trileaflet aortic valve with mild aortic insufficiency (N = 58, 0.29%). Evolution of USAF waiver policy has now rendered these diagnoses waiverable for entry into pilot training. Under current policy, 285/294 would be eligible for an unrestricted waiver, leaving only 9 individuals "DQ/no-waiver" (0.0445%). There were no cases of hypertrophic cardiomyopathy. Although the number of USAF pilot applicants has increased in recent years, the DQ/no-waiver rate has actually decreased, with only a single DQ/no-waiver finding since 2004 (N = 5802 studies; 0.0172%). DISCUSSION: The infrequency of positive findings in this large cohort of screening echocardiography raises questions about the appropriateness of such programs. Under current USAF policy, it is not efficacious to perform screening echocardiography on all pilot applicants.

Cardiac ischemia model for +Gz using miniature swine and baboons.

BACKGROUND: Military aircrew with minimal coronary artery disease (MCAD) may be restricted from flying high-performance aircraft due to possible ischemia during high +Gz. An animal model is presented to provide ischemia data for a more informed decision. METHODS: There were 18 swine that were placed on a high cholesterol/high fat diet for up to 57 wk. Five control swine were maintained on a standard swine diet. Also, nine male baboons had a constrictor placed around the left anterior descending coronary artery. Two baboons were sham-operated controls. The unanesthetized swine and baboons were infused with Tc-99m at the end of +Gz exposure and scanned for myocardial perfusion. RESULTS: Five swine died unexpectedly before +Gz exposure with moderate-to-severe CAD. Dysrhythmias during +Gz were seen equally in both the control and experimental swine and in the baboons before and after stenosis, with or without propranolol. During +Gz, ECG ST-T wave changes suggesting ischemia were observed in the cholesterol swine but not the control swine, and in the baboons before and after stenosis, with or without propranolol. There was a positive relationship between a normal/abnormal ECG and a normal/abnormal myocardial perfusion scan in the swine and a weak relationship in the baboon before stenosis, but somewhat better after stenosis. Coronary histopathology showed normal vessels from the control swine and stenoses ranging from 0-95% from the cholesterol swine. Baboon stenosis averaged 37.6 +/- 15.0%. CONCLUSIONS: In the swine and the baboon extended high levels of +Gz, were associated with evidence of myocardial ischemia.

Military aviators with mitral valve prolapse: long-term follow-up and aeromedical endpoints.

INTRODUCTION: Mitral valve prolapse (MVP) is a disqualifying condition for USAF aviators. Trained USAF aviators, and in recent years flying training applicants, may be granted waiver for initial or continued flying duties following extensive, periodic evaluation. This study examines the usefulness of the various tests performed in that evaluation process and provides long-term follow-up from 404 USAF flyers with MVP. METHODS: We retrospectively reviewed 2-dimensional echocardiography, Holter monitoring, treadmill exercise, thallium imaging, coronary fluoroscopy, cardiac catheterization, and centrifuge testing results from 404 military aviators evaluated at the Aeromedical Consultation Service between 1 January 1972 and 31 October 1993. Follow-up was achieved through questionnaires (91%) and death certificates, etc. RESULTS: Mean follow-up was 8.6 yr (range 1-21 yr). Age at study entry was 21 to 64 yr (mean = 36 yr). The occurrence rate for suddenly incapacitating events (sudden cardiac death, syncope, pre-syncope, and cerebral ischemic episodes) was 0.32%/yr. CONCLUSIONS: Echocardiographic MVP in military aviators is associated with a low but statistically increased prevalence of "incapacitating" aeromedical events. Univariate predictors of adverse outcome included study entry with an enlarged left ventricle or left atrium, cardiovascular symptoms or findings, or MVP with thickened leaflets. Evaluation of coronary artery disease (CAD) in this population, absent specific indicators of CAD risk, is not indicated.

Transcatheter PFO closure in an aircrew member with cryptogenic stroke: aeromedical disposition.

Stroke is an uncommon event among military aircrew, partly because that population tends to be younger and healthier than typical stroke victims. Aircrew members suffering stroke rarely have identifiable risk factors or etiology that can be treated or modified such that return to flying duties is a consideration. In this case, an aircrew member was found to have a patent foramen ovale (PFO) during his stroke evaluation. Several studies support the association between PFO and cryptogenic stroke, but literature clearly defining the need for PFO repair in the context of cryptogenic stroke is still incomplete. On clinical recommendation from his providers, this aircrew member underwent elective closure of his PFO with a transcatheter device. After complete recovery from his stroke and an apparently successful PFO closure, he requested return to flying duties. History of stroke and PFO closure with transcatheter device were both disqualifying conditions according to United States Air Force Instructions. This case is presented as an example of an aeromedical decision-making process when confronted with an unusual case such as this.

Cases from the aerospace medicine residents' teaching file. Case report of an aviator with focal myocarditis mimicking myocardial infarction with normal coronaries.

A military aviator was initially diagnosed with myocardial infarction following a viral syndrome. Confusion about recurrence of chest pain versus gastritis led to his continued cardiac patient status until this was clarified diagnostically. He was presumed to have had coronary vasospasm, and was treated with a calcium channel blocker. Absent his strong desire to return to flying duties, he may have continued in that diagnostic pathway indefinitely. After thorough aeromedical evaluation, resolved focal viral myocarditis was felt to be the most likely diagnosis and he was returned to military flying duties.

Sudden incapacitation: occupational aviation medicine perspectives.

Within the aviation environment, occupational medicine tends to focus on pilots, because of the very great effects pilot injury or illness can have on public safety. However, medical conditions of other aviation workers can also endanger public and personal safety. Sudden incapacitation an abrupt loss or impairment of consciousness, control, or performance is the most important occupational concern in aviation medicine. The authors discuss the neurologic causes of sudden incapacitation and syncope, and evaluate the risks of returning affected pilots to duty. Also offered is a Controversy (Single Seizure: To Treat or Not To Treat).