Negative impact of high-performance flights on aviators with mitral valve prolapse.

BACKGROUND: While it appears not to affect healthy aviators' hearts, there are scarce data regarding the impact of high-performance flights on aviators with mitral valve prolapse (MVP). METHODS: A retrospective, comparative cohort study of military aviators with MVP. Subjects were categorized to either high-performance (jet fighter) or low-performance (transport and helicopter) aviators. The primary outcomes were the rates of mitral interventions and of adverse cardiovascular events since being an aircrew candidate and up to the end of flying career. Additional outcomes were echocardiographic measurements and the cumulative proportion of mitral valve interventions over time. RESULTS: Of 33 male aviators with MVP, 18 were high-performance aviators. On average, follow-up started at age 18.5 years and lasted 27.8 ±â€¯10.1 years. Baseline characteristics were similar between the study groups. Aviators of high-performance aircraft had increased rates of mitral valve surgery (33 % vs. 0, p = 0.021), MVP-related complications (39 % vs. 6.7 %, p = 0.046), and a higher incidence of mitral valve repair over time (p = 0.02). High-performance flight was associated with increased intraventricular septum thickness (IVS, 9.7 mm vs 8.9 mm, p = 0.015) and IVS index (p = 0.026) at the last echocardiographic assessment. High-performance aviators tended to develop worsening severity of mitral regurgitation. CONCLUSIONS: High-performance flight may be associated with an increased risk for valvular deterioration and need for mitral surgery in aviators with MVP.

Interventricular Septum and Posterior Wall Thickness Are Associated With Higher Systolic Blood Pressure.

Elevated blood pressure (BP) is a known factor that affects the structure of the left ventricle. The association between left ventricular hypertrophy (LVH) and BP in normotensive individuals is poorly understood. All individuals who underwent routine echocardiography and BP measurements as aircrew candidates for the Israeli Air Force in the years 2006 to 2012 were identified. Participants with normal values were included. Associations between echocardiographic characteristics and BP were studied. A total of 2386 participants were included. Mean systolic BP was 125.31±11.18 mm Hg and mean diastolic BP was 68.69±9.02 mm Hg. Interventricular septal (IVS) thickness was positively correlated with systolic BP (P<.001, correlation coefficient 0.121) and significantly inversely correlated with heart rate and hematocrit level (P<.001 for both). Men with evidence of IVS or posterior wall thickening on echocardiography, even within the normal range, may require a closer follow-up of BP.

M-mode echocardiographic values in a cohort of young healthy individuals.

OBJECTIVES: To determine normal M-mode values in healthy young adults and to evaluate whether these values differ among those in whom echocardiography was performed routinely and those in whom echocardiography was performed based on clinical grounds. METHODS: A cross-sectional study evaluating a large cohort of young academy applicants of the Israeli air force in the years 1994-2010. Studies were divided into those performed routinely and those performed because of abnormal ECG or physical examination findings. Echocardiographic variables were compared between the two groups and values are expressed as mean ±â€ŠSD. RESULTS: Echocardiography was performed routinely in 3525 applicants (age 18.5 ±â€Š1.0 years) and following a clinical referral in 3517 applicants (age 18.2 ±â€Š0.9 years). Those in whom echocardiography was performed routinely had slightly higher left ventricular end-systolic diameter (31.2 ±â€Š3.3  vs. 30.7 ±â€Š3.4 mm; P < 0.0001) and aortic root diameter (28.5 ±â€Š2.1 vs. 27.9 ±â€Š2.2 mm; P < 0.0001), and slightly lower left ventricular mass index (108.8 ±â€Š15.8  vs. 109.9 ±â€Š16.5 g/m; P = 0.005). No differences were noted between the two groups in left atrial diameter, left ventricular end-diastolic volume, posterior wall thickness and interventricular septum thickness. CONCLUSION: Certain M-mode characteristics may differ (although to a slight degree) in young healthy individuals with electrocardiographic and physical findings compared with those with normal physical examination and electrocardiography.

Cardiac indexes in young subjects with and without bicuspid aortic valve.

OBJECTIVES: Bicuspid aortic valve (BAV) is a common congenital anomaly. The aeromedical implications of this condition are unclear. This study attempts to evaluate a possible association between BAV with or without aortic regurgitation (AR) and cardiac and aortic morphology in young healthy subjects. METHODS: Air force academy applicants undergo routine echocardiography as part of the screening process. All echocardiographic examinations performed in the years 2004-2011 were evaluated. Applicants in whom BAV was identified were divided into those with and without aortic regurgitation. Both groups were compared with an age-matched group of applicants in whom echocardiography was interpreted as normal. All M-mode parameters were compared between the three groups. RESULTS: There were 7042 echocardiographic examinations performed in the years 2004-2010 and 95 applicants (1.35%) were diagnosed with BAV. Of these, 34 applicants had AR (36%) and 61 had no AR. When compared with normal subjects, systolic blood pressure was higher in applicants with BAV (127 mmHg vs. 123 mmHg, P = 0.01). Aortic root diameter, left atrial diameter, left ventricular end systolic volume, interventricular septum thickness and posterior wall thickness were all increased in applicants with BAV compared with applicants without BAV. In those with BAV, no statistically significant differences in M-mode characteristics were noted between applicants with and without aortic regurgitation. CONCLUSIONS: BAV in young healthy subjects may influence cardiac morphology irrespective of the presence of aortic regurgitation. Aeromedical disposition for patients with BAV should be based on the presence of the condition and not on the presence of AR, considering the AR is of a mild or minimal degree.

Correlation between spirometry values and pulmonary artery pressure in young healthy subjects.

BACKGROUND: Pulmonary hypertension is frequently associated with parenchymal lung disease. We evaluated the association between spirometry values and pulmonary artery systolic pressure (PASP) in young subjects without lung disease METHODS: : We studied applicants to the Israeli Air Force, who undergo routine evaluation that includes resting spirometry and echocardiography. Applicants with overt lung disease were excluded. All echocardiographic studies performed in the years 1994 through 2010 (n = 6,598) were screened, and files that included PASP and spirometry values were analyzed for the association between PASP and FVC, FEV1, FEV1/FVC, peak expiratory flow, and forced expiratory flow during the middle half of the FVC maneuver. RESULTS: Of the 647 air force applicants who underwent echocardiography in which PASP was measurable and had spirometry data, 607 (94%) were male, and their average age was 18.16 ± 0.73 years. Mean PASP was 26.4 ± 5.2 mm Hg (range 10-41 mm Hg). None of the spirometry values significantly correlated with PASP. CONCLUSIONS: PASP in young healthy subjects is not significantly associated with spirometry values. Lung mechanics probably do not contribute significantly to PASP in this population.

Inter-arm blood pressure differences in young, healthy patients.

The prevalence and magnitude of inter-arm BP difference (IAD) in young healthy patients is not well characterized. Flight academy applicants and designated aviators undergo annual evaluation that includes blood pressure (BP) measurement on both arms. All BP measurements performed from January 1, 2012, to April 30, 2012, were recorded and IAD was calculated. Results were compared between patients in whom BP was initially measured in the right arm (group 1), those in whom BP was initially measured in the left arm (group 2), and those in whom the arm in which BP was initially measured was not recorded (group 3). A total of 877 healthy patients had BP measured during the study period. In the entire group, mean systolic BP was the same in both arms. Absolute IAD was 5.6±5.5 mm Hg for systolic and 4.7±4.5 mm Hg for diastolic BP. IAD >10 mm Hg was recorded in 111 (12.6%) and 77 (8.8%) patients for systolic and diastolic BP, respectively. IAD was the same in the 3 groups and was unrelated to age, body mass index, and heart rate, but was related to systolic BP. IAD is common in young healthy patients, is not dependent on which arm was measured first, and unrelated to age, body mass index, and heart rate.

Pre-participation ECG screening in military recruits.

BACKGROUND: The findings and additional investigations required based on pre-participation electrocardiography (ECG) among military recruits are poorly defined in the literature. OBJECTIVES: This study was designed to evaluate the rate of abnormal findings on pre-participation ECG in young adults and the additional evaluations required based on these findings. METHODS: A retrospective cohort study was performed in the Israeli Air Force (IAF) aero medical screening center for flight academy and elite units' candidates. Flight academy and elite units' candidates undergo pre-participation ECG prior to enlistment to the Israeli Defense Forces (IDF). Since 2010, all ECGS have been performed at the IAF aero medical center. All ECGs performed since January 2010 were analyzed by one of three cardiologists and all those in which significant findings were identified were referred to further evaluation upon the cardiologist's request. Causes of referral for further evaluation, the evaluations performed and the results of these evaluations are reported for the study population. RESULTS: 1455 ECGS were performed in the years 2010-2011. Of these, 1388 (95.39%) were interpreted as normal. 67 subjects were referred to further evaluation based on ECG findings. The most common findings leading to further evaluation were T wave changes (16 cases, 23.88%), pre-excitation pattern (14, 20.89%) and voltage criteria for left ventricular hypertrophy (11, 16.41%). Only 7 subjects (10.44%) had abnormal findings which were considered clinically significant at the end of the medical evaluation. CONCLUSIONS: The rate of significant findings leading to disqualification from military activity is extremely low and referral to continued investigations based on 12-lead ECG findings should be judicious.

Triagem pré-participação com ECG em recrutas militares / Pre-participation ECG screening in military recruits

FUNDAMENTO: Os achados e investigações adicionais necessários com base na triagem pré-participação com eletrocardiograma (ECG) entre os recrutas militares estão mal definidos na literatura. OBJETIVOS: Este estudo foi elaborado para avaliar a taxa de achados anormais na triagem pré-participação com ECG em adultos jovens e as avaliações adicionais necessárias com base nestes resultados. MÉTODOS: Um estudo de coorte retrospectivo foi realizado no centro aero-médico da Força Aérea de Israel (IAF), para candidatos das unidades das academias de voo e de tropa s de elite. Os candidatos das unidades das Academias de voo e de elite passam por uma triagem pré-participação com ECG antes do alistamento nas Forças de Defesa de Israel (IDF). Desde 2010, todos os ECGs são realizados no centro aero-médico da IAF. Todos os ECGs realizados desde janeiro de 2010 foram analisados por um de três cardiologistas e todos aqueles nos quais resultados significativos foram identificados foram encaminhados para uma avaliação mais detalhada, a pedido do cardiologista. As causas de encaminhamento para avaliação posterior, as avaliações realizadas e os resultados dessas avaliações são notificados para a população de estudo. RESULTADOS: 1.455 ECGs foram realizados nos anos 2010-2011. Desses, 1.388 (95,39%) foram interpretadas como normais. 67 indivíduos foram encaminhados para uma avaliação mais detalhada com base nos achados do ECG. Os achados mais comuns levando a uma avaliação mais detalhada foram alterações da onda T (16 casos, 23,88%), padrão de pré-excitação (14, 20,89%) e critérios de voltagem para hipertrofia ventricular esquerda (11; 16,41%). Apenas 7 indivíduos (10,44%) tinham resultados anormais que foram considerados clinicamente significativos no final da avaliação médica. CONCLUSÕES: A taxa de achados significantes levando à desqualificação para a atividade militar é extremamente baixa e o encaminhamento para investigações adicionais baseado nos achados do ECG de 12 derivações deve ser criterioso.

BACKGROUND:The findings and additional investigations required based on pre-participation electrocardiography (ECG) among military recruits are poorly defined in the literature. OBJECTIVES: This study was designed to evaluate the rate of abnormal findings on pre-participation ECG in young adults and the additional evaluations required based on these findings. METHODS: A retrospective cohort study was performed in the Israeli Air Force (IAF) aero medical screening center for flight academy and elite units' candidates. Flight academy and elite units' candidates undergo pre-participation ECG prior to enlistment to the Israeli Defense Forces (IDF). Since 2010, all ECGS have been performed at the IAF aero medical center. All ECGs performed since January 2010 were analyzed by one of three cardiologists and all those in which significant findings were identified were referred to further evaluation upon the cardiologist's request. Causes of referral for further evaluation, the evaluations performed and the results of these evaluations are reported for the study population. RESULTS: 1455 ECGS were performed in the years 2010-2011. Of these, 1388 (95.39%) were interpreted as normal. 67 subjects were referred to further evaluation based on ECG findings. The most common findings leading to further evaluation were T wave changes (16 cases, 23.88%), pre-excitation pattern (14, 20.89%) and voltage criteria for left ventricular hypertrophy (11, 16.41%). Only 7 subjects (10.44%) had abnormal findings which were considered clinically significant at the end of the medical evaluation. CONCLUSIONS: The rate of significant findings leading to disqualification from military activity is extremely low and referral to continued investigations based on 12-lead ECG findings should be judicious.

Comparison of usefulness of Sokolow and Cornell criteria for left ventricular hypertrophy in subjects aged <20 years versus >30 years.

The use of electrocardiography in sports or military screening is considered an effective tool for diagnosing potentially fatal conditions. The present study was designed to compare the yield of electrocardiographic criteria for left ventricular hypertrophy (LVH) criteria for the diagnosis of LVH and hypertrophic obstructive cardiomyopathy in subjects aged <20 years and >30 years. The association between the electrocardiographic (ECG) criteria for LVH (ECG-LVH) and echocardiographic findings was compared in 4 groups of air force academy candidates: (1) young candidates undergoing echocardiography because of ECG-LVH findings (n = 666); (2) young candidates without ECG-LVH findings undergoing routine echocardiography (n = 4,043); (3) older designated aviators undergoing echocardiography because of ECG-LVH findings (n = 196); and (4) older designated aviators undergoing routine echocardiography without ECG-LVH findings (n = 1,098). The predictive value of ECG-LVH findings for echocardiographic LVH, left ventricular mass, posterior wall thickness, and interventricular septal thickness were compared among the 4 groups. The ECG criteria in young subjects correlated with the left ventricular mass and posterior wall thickness but not with the interventricular septal thickness. In older subjects, these criteria correlated with left ventricular mass, interventricular septal, and posterior wall thickness. The positive and negative predictive value of ECG-LVH findings for the echocardiographic diagnosis of LVH in young subjects was 6.0% and 99.0%, respectively. In older subjects the positive and negative predictive value of ECG-LVH findings was 34% and 93%, respectively. In conclusion, ECG criteria are probably a useful tool for exclusion of LVH in young and older subjects; however, their low positive predictive value would probably lead to unnecessary echocardiographic tests, particularly in young subjects.

Pulmonary artery pressure in young healthy subjects.

BACKGROUND: Pulmonary artery systolic pressure (PASP) is frequently measured noninvasively using transthoracic echocardiography. Normal values of PASP are based on studies performed in heterogeneous populations. The normal values of PASP in young healthy subjects are poorly defined. The aim of this study was to describe the distribution and clinical and morphologic correlates of PASP values in young healthy subjects. METHODS: Echocardiography is routinely performed for aircrew candidates for the Israeli Air Force. All echocardiographic examinations performed between 1994 and 2010 in which tricuspid regurgitation was present, a prerequisite for echocardiographic PASP measurement, were collected. Subjects with morphologic abnormalities were excluded. PASP was calculated using the simplified Bernoulli equation, with right atrial pressure assumed to be 5 mm Hg. The associations between PASP and clinical and echocardiographic characteristics were studied. RESULTS: Subjects were healthy young adults aged 17 to 29 years. Evidence of tricuspid regurgitation was found in 1,900 of 6,598 subjects. The estimated mean PASP value was 31.2 ± 4.5 mm Hg, and the upper 95th percentile was 34 mm Hg. In univariate analysis, PASP was correlated with left ventricular end-diastolic and end-systolic diameters. A multivariate linear regression model including age; diastolic blood pressure; echocardiographic measurements of aortic root, left atrial, and left ventricular end-diastolic diameters; and left ventricular mass explained only 7% of the variability in PASP. CONCLUSIONS: PASP in young, physically fit subjects may be higher than previously reported in the general population and is poorly explained by age, blood pressure, and other echocardiographic parameters.

Acceleration forces and cardiac and aortic indexes in jet fighter pilots.

BACKGROUND: Military jet fighter pilots are exposed to acceleration (+G(z)) forces which possibly influence various cardiac parameters. Several previous studies have evaluated the impact of exposure to acceleration forces on cardiac morphology and function, but these studies were not prospective and were either based on small samples or compared jet fighter pilots with pilots of low-performance aircraft. The purpose of this study was to evaluate the effect of acceleration forces on cardiac morphologic changes in jet fighter pilots. METHODS: Routine echocardiography has been performed for jet fighter pilots since 2003. Medical records of all military jet fighter pilots who underwent echocardiography following 2003 were retrospectively evaluated. Of those, all jet fighter pilots who underwent an additional echocardiography prior to 2003 were identified. Echocardiographic parameters were recorded using M-mode and included left ventricular diameter at end systole and end diastole, interventricular septum thickness, thickness of the posterior wall, aortic root diameter and aortic valve opening, diameter of the left atrium, and left ventricular mass. Medical records of the subjects were evaluated for development of adverse events. RESULTS: There were 72 subjects who underwent 2 echocardiographic examinations with a mean follow-up period of 8.92 yr. Subjects were 18-50 yr old at the time of the initial echocardiographic examination. All parameters evaluated by M-mode were not significantly changed from the baseline examination. No adverse events occurred during the follow-up period. DISCUSSION: Findings of this study suggest that exposure to acceleration forces is not associated with cardiac and aortic morphologic changes.

Echocardiographic evaluation and follow-up of cardiac and aortic indexes in aviators exposed to acceleration forces.

BACKGROUND: Military jet fighter pilots are routinely exposed to acceleration (+Gz) forces. This recurrent exposure may influence various cardiac parameters. A few previous studies have evaluated the impact of exposure to acceleration forces on cardiac morphology and function, but these studies were mostly based on small cohorts, and subjects did not undergo baseline echocardiographic examinations before +Gz exposure. METHODS: Ninety-six jet fighter pilots with high +Gz exposure underwent echocardiographic evaluation before and 7 to 12 years after repeated +Gz exposure. Echocardiographic parameters were recorded using M-mode echocardiography and included left ventricular diameter at end-systole and end-diastole, interventricular septal thickness, thickness of the posterior wall, aortic root diameter and aortic valve opening, diameter of the left atrium, and left ventricular mass. Medical records of the subjects identified were evaluated for the development of adverse events. RESULTS: The average age at the time of the initial echocardiographic examination was 19.2 years. All subjects were healthy, without cardiovascular risk factors, and had no prior exposure to acceleration forces. The average flying period on jet planes at the time of follow-up examination was 1,812 hours. The mean follow-up period was 9.13 years. All parameters evaluated by M-mode echocardiography were not significantly changed from the baseline examination. No adverse events occurred during the follow-up period. CONCLUSIONS: Exposure to acceleration forces has no significant impact on cardiac and aortic morphology.

Natural history of mitral valve prolapse in military aircrew.

OBJECTIVE: Mitral valve prolapse (MVP) is a common cardiac abnormality whose natural history differs among various patient populations. High-performance flight is associated with exposure to varying acceleration forces and strenuous isometric physical activity. The effect of the military flying environment on the natural history and progression of MVP is poorly defined. METHODS: We evaluated a cohort which included all military aviators in the Israeli Air Force diagnosed with MVP. Medical records and echocardiographic studies of participants were reviewed for the development of clinical or echocardiographic complications. RESULTS: The study population was comprised of 24 aviators, 14 of whom were high-performance aviators. Average follow-up was 23.5 years (total 563 person-years). Four aviators suffered from MVP-related complications including 2 cases of flail valve due to chordae rupture and 1 case each of newly diagnosed atrial fibrillation and infective endocarditis. Progression of asymptomatic mitral regurgitation was identified in 11 aviators. CONCLUSIONS: Military aviators with MVP may be prone to serious medical complications. A detrimental effect of high-performance flight on patients with MVP is suggested.

Effects of repeated exposure to acceleration forces (+Gz) and anti-G manoeuvres on cardiac dimensions and performance.

Exposure to acceleration forces (+Gz) and anti-G protective manoeuvres causes changes in cardiac preload and afterload. These changes can result in cardiac hypertrophy or enlargement. Previous studies regarding the effect of acceleration in high-G aviators (HGAs) are few and inconclusive. An echocardiographic study was initiated to determine whether there are structural or functional cardiac differences between HGAs and low-G aviators (LGAs).The present study was a cross-sectional study in which echocardiographic parameters in HGAs were compared with those in LGAs. Both retrospective and prospective data were collected. Fifty aviators were included in each group. The aviators who participated in the present study were randomly chosen from a cohort with similar demographic characteristics and flying hours. No major differences were found in cardiac dimensions and function between HGAs and LGAs. The authors speculate that the reason why no major differences were found was due to the short period of total exposure to very high +Gz forces and anti-G measures.

Screening echocardiography of military aircrew candidates: aeromedical implications.

OBJECTIVES: Cardiovascular evaluation has a significant aspect in the medical screening process of aircrew candidates. Echocardiography may identify asymptomatic cardiac abnormalities which can jeopardize the aviator and flight safety, as well as conditions which may progress and disqualify a trained aviator. We assessed the value of adding routine echocardiography to the aeromedical screening process. METHODS: The study population consisted of 17- to 21-year-old healthy aircrew candidates. We retrospectively reviewed all routine echocardiographic studies performed during 1997-2008 at our clinic. Studies performed for a clinical indication were excluded. RESULTS: A total of 2,657 echocardiographic studies were analyzed. 2,506 were considered 'normal' (94.3%). 151 studies (5.7%) demonstrated findings which required further consideration and were considered 'abnormal'. Additional consideration included limitation to low-performance aircrafts (n = 22, 14.7%), prompt disqualification (n = 23, 15.3%), or further cardiovascular assessment (n = 106, 70% of 'abnormal' studies), which resulted in disqualification of 2 more candidates. Echocardiography resulted in disqualification of 0.94% of candidates, limitation to low-performance aircrafts in 0.83%, and need for follow-up in additional 1.54%. CONCLUSIONS: Echocardiographic screening affected aeromedical designation and follow-up decisions in 3.31% of candidates. Contribution of routine echocardiography is dependent on aeromedical policies. The Israeli Air Force policies regarding common findings are presented.