Management of cardiac conduction abnormalities and arrhythmia in aircrew

Management of atrial fibrillation in German military aircrew

INTRODUCTION

Arrhythmias are one of the most common causes of loss of flying privileges for both military and civilian pilots in the Western World, and atrial fibrillation (AF) is one of the most common arrhythmias worldwide. Aircrew, and particularly pilots, are subject to a unique and exacting working environment, especially in high-performance military aircraft. This manuscript analyzes AF cases in German military aircrew from both a clinical and occupational perspective to point out specific characteristics in this comparatively young, highly selected, and closely monitored group, and to discuss AF management with the aim of a return to flying duties.

METHODS

The digital information systems of the German Air Force Centre of Aerospace Medicine (GAFCAM) were searched for aircrew (pilot and non-pilot aircrew from German Air Force, Army, and Navy) with the diagnosis of AF. Evaluation results for underlying disease, AF characteristics, important clinical findings, and occupational decisions were analyzed in the light of current clinical guidelines and aeromedical regulations.

RESULTS

In a 34-year period, between March 1989 and January 2023, 42 aircrew with at least one episode of AF were registered, all of them were male. The median age at initial diagnosis was 47 years (min 22 years, max 62 years). The median follow-up period was 5.35 years. 19 of them (45%) were pilots. The breakdown of events and occurrence was found to be: single (23), paroxysmal (16), persistent (2), permanent (1). In 27 aircrew (64%) AF terminated spontaneously. Long-term recurrence prevention was variable with catheter ablations in 8 cases. 36/42 aircrew were returned to flight status with restrictions, while 6/42 were permanently disqualified from flying.

CONCLUSION

Management of AF in military aircrew requires a comprehensive approach regarding the flight environment as well as clinical guidance. Aeromedical disposition should be case-by-case based on aeromedical regulations, individual clinical findings, and specific occupational requirements in this challenging field of work.

Return to Flying After Catheter Ablation of Arrhythmic Disorders in Military Aircrew

INTRODUCTION: Catheter ablation is a widely used and effective treatment option for many tachyarrhythmic disorders. This study analyzes all ablation cases in German military aircrew over a 17-yr period. Recurrence of different arrhythmias and ablation complications were analyzed with an aim of refining specific recommendations for aircrew employment.METHODS: All cases of catheter ablations in pilots and nonpilot aircrew examined at the German Air Force Centre of Aerospace Medicine from 2004 to 2020 were analyzed for sex, age, concomitant diseases, ablated arrhythmias, complications, recurrences, time elapsed from ablation to reablation, number of ablations, and aeromedical disposition, including restrictions in case of a return to flying duties.RESULTS: There were 36 aircrew who underwent catheter ablation; 7 were ablated for 2 or more different arrhythmias; 10 underwent more than one ablation. Ablated arrhythmias included atrioventricular (AV) nodal re-entrant tachycardias, accessory pathways, focal atrial tachycardias, typical and atypical atrial flutter, atrial fibrillation, and premature atrial and ventricular complexes. Recurrence rates differed between the arrhythmias and were lowest in AV re-entrant tachycardias. Complication rates were low.CONCLUSION: In this aircrew cohort, nearly all aircrew were able to return to flying duties following ablation, albeit some with restrictions. Restrictions depended on the underlying arrhythmia, the ablation procedure, and the symptoms prior to ablation. A basic understanding of different arrhythmias, ablation techniques, and long-term success rates is essential for the AME and for the responsible licensing authority. Close cooperation with an electrophysiologist is necessary prior to and after ablation to ensure optimal management of aircrew with arrythmias.Guettler N, Nicol E, Sammito S. Return to flying after catheter ablation of arrhythmic disorders in military aircrew. Aerosp Med Hum Perform. 2022; 93(10):725–733.

Exercise ECG for Screening in Military Aircrew

INTRODUCTION: The exercise electrocardiogram (ExECG), or stress test, is a widely used screening tool in occupational medicine designed to detect occult coronary artery disease, and assess performance capacity and cardiovascular fitness. In some guidelines, it is recommended for high-risk occupations in which occult disease could possibly endanger public safety. In aviation medicine, however, there is an ongoing debate on the use and periodicity of ExECG for screening of aircrew.METHOD: In the German Armed Forces, aircrew applicants and active-duty aircrew undergo screening ExECG. We analyzed 7646 applicant ExECGs (5871 from pilot and 1775 from nonpilot applicants) and 17,131 ExECGs from 3817 active-duty pilots. All were performed at the German Air Force Centre of Aerospace Medicine (GAFCAM) and analyzed for ECG abnormalities, performance capacity, blood pressure, and heart rate response.RESULTS: Only 15/5871 (0.2%) of pilot applicants required further investigation and none were ultimately disqualified for aircrew duties due to their ExECG results. Of the nonpilot applicants, 22/1775 (1.2%) required further diagnostic work-up due to their ExECG findings, with only 1 ultimately disqualified. From active-duty pilots, 84/17,131 (0.5%) ExECGs revealed findings requiring further investigation, with only 2 pilots ultimately disqualified from flying duties.DISCUSSION: The extremely low yield of ExECG findings requiring further evaluation and/or disqualification for aircrew duties suggest its use is questionable and not cost-effective as a screening tool in this cohort. It may be enough to perform ExECG on clinical indication alone.Guettler N, Nicol ED, Sammito S. Exercise ECG for screening in military aircrew. Aerosp Med Hum Perform. 2022; 93(9):666–672.

Characteristics of United States military pilots with atrial fibrillation and deployment and retention rates

Introduction

Atrial fibrillation (AF) is an arrhythmia that impacts deployment and retention rates for United States military pilots. This study aims to characterize United States active duty (AD) pilots with AF and review deployment and retention rates associated with medical and ablative therapies.

Methods

An observational analysis was performed to assess AD pilots diagnosed with AF in the largest military regional healthcare system from 2004 to 2019. Baseline characteristics and AF management were reviewed.

Results

27 AD pilots (mean age, 37.3 ± 7.9 years; mean BMI, 27.3 ± 3.1 kg/m²; 100% male sex) were diagnosed with AF during the study dates. 17 (63%) were Air Force branch pilots with hypertension as the most common risk factor (26%). There were overall low CHA₂DS₂-VASc scores (mean 0.29 ± 0.47). 22 (82%) pilots were equally treated with medical rate and rhythm strategies (41% and 41%, respectively). 16 (59%) underwent pulmonary vein isolation (PVI) with zero complications. 11 (41%) pilots received warfarin and 5 (19%) received a direct oral anticoagulant for stroke prevention. After diagnosis, 12 (44%) pilots deployed and 25 (93%) were retained in military. PVI was not associated with a change in subsequent deployments rates (PVI, 38% vs no PVI, 55%; p = 0.3809) or retention rates (PVI, 94% vs no PVI, 91%; p = 0.7835).

Conclusions

United States military pilots diagnosed with AF are younger patients with few traditional AF risk factors and  they receive medical rate and rhythm strategies equally. Many pilots maintain deployment eligibility and most remain on AD status after diagnosis. PVI is not associated with differences in retention or deployment rates. Further prospective study is needed to further evaluate these findings. 

Driver Cardiovascular Disease Detection Using Seismocardiogram

This article deals with the treatment and application of cardiac biosignals, an excited accelerometer, and a gyroscope in the prevention of accidents on the road. Previously conducted studies say that the seismocardiogram is a measure of cardiac microvibration signals that allows for detecting rhythms, heart valve opening and closing disorders, and monitoring of patients' breathing. This article refers to the seismocardiogram hypothesis that the measurements of a seismocardiogram could be used to identify drivers' heart problems before they reach a critical condition and safely stop the vehicle by informing the relevant departments in a nonclinical manner. The proposed system works without an electrocardiogram, which helps to detect heart rhythms more easily. The estimation of the heart rate (HR) is calculated through automatically detected aortic valve opening (AO) peaks. The system is composed of two micro-electromechanical systems (MEMSs) to evaluate physiological parameters and eliminate the effects of external interference on the entire system. The few digital filtering methods are discussed and benchmarked to increase seismocardiogram efficiency. As a result, the fourth adaptive filter obtains the estimated HR = 65 beats per min (bmp) in a still noisy signal (SNR = −11.32 dB). In contrast with the low processing benefit (3.39 dB), 27 AO peaks were detected with a 917.56-ms peak interval mean over 1.11 s, and the calculated root mean square error (RMSE) was 0.1942 m/s2 when the adaptive filter order is 50 and the adaptation step is equal to 0.933.

Electrocardiographic abnormalities in medically screened German military aircrew

BACKGROUND

A resting electrocardiogram (ECG) is a well-tolerated, non-invasive, and inexpensive test for overt electrical signs of cardiac pathology and is widely used in the screening of aircrew and other high-hazard occupations. Given the low number of pathological results leading to disqualification or restriction however, there is an ongoing debate as to how often screening ECGs should be performed in different age groups.

METHODS

We restrospectively analyzed 8275 resting 12-lead ECGs registered between 2007 and 2020 in the German Air Force Centre of Aerospace Medicine. Findings were categorized according to consensus recommendations published by the NATO Working Group on Occupational Cardiology in Military Aircrew, based on ECG screening criteria published for athletes which were used at the time of registration. Age, sex, height, weight, and body mass index of the probands were also captured. Additionally, 4839 pilot and non-pilot aircrew members were analyzed longitudinally over a maximum period of 13.4 years.

RESULTS

Out of all the ECGs only 18 revealed findings requiring further investigation, and only one individual was temporarily disqualified because of a ventricular pre-excitation (delta wave) as a sign of an antegrade conducting accessory pathway. The longitudinal analysis of 25,829 ECGs revealed 28 abnormalities requiring further investigation, and only two ECG findings (in probands aged 48.8 and 59.1 years) led to temporary, or permanent disqualification. In a third case, the ECG showed signs of a myocardial infarction, which was already known from the proband's history.

CONCLUSIONS

Initial ECG screening for asymptomatic aircrew revealed extremely low numbers of individuals requiring further investigation in our cohort. This would appear to justify an initial screening ECG and follow-up ECGs at certain intervals starting at a certain age, but routine ECG screening of applicants in professions with a higher risk tolerance or frequent, e.g. annual, follow-up ECGs in younger aircrew is not supported by our data because of the minimal yield of ECG findings requiring further investigation.

Gravitational Influence on Human Living Systems and the Evolution of Species on Earth

Gravity constituted the only constant environmental parameter, during the evolutionary period of living matter on Earth. However, whether gravity has affected the evolution of species, and its impact is still ongoing. The topic has not been investigated in depth, as this would require frequent and long-term experimentations in space or an environment of altered gravity. In addition, each organism should be studied throughout numerous generations to determine the profound biological changes in evolution. Here, we review the significant abnormalities presented in the cardiovascular, immune, vestibular and musculoskeletal systems, due to altered gravity conditions. We also review the impact that gravity played in the anatomy of snakes and amphibians, during their evolution. Overall, it appears that gravity does not only curve the space–time continuum but the biological continuum, as well.

Characteristics of US military personnel with atrial fibrillation and associated deployment and retention rates

INTRODUCTION

Atrial fibrillation (AF) is an arrhythmia impacting military occupational performances. Despite being a recognised disqualifying condition, there is no literature describing US military service members with AF. This study aims to describe members with AF diagnoses, the distribution of treatment strategies and associated deployment and retention rates.

METHODS

Active duty service members identified with AF from 2004 to 2019 were investigated. Cardiovascular profiles, AF management strategies and military dispositions were assessed by electronic medical record review.

RESULTS

386 service members (mean age 35.0±9.4 years; 94% paroxysmal AF) with AF diagnoses were identified. 91 (24%) had hypertension followed by 75 (19%) with sleep apnoea. Mean CHA₂DS₂-VASc scores were low (0.39±0.65). Rhythm treatments were used in 173 (45%) followed by rate control strategies in 155 (40%). 161 (42%) underwent pulmonary vein isolation (PVI). In subgroup analysis of 365 personnel, 147 (40%) deployed and 248 (68%) remained active duty after AF diagnosis. Deployment and retention rates did not differ between those who received no medical therapy, rate control or rhythm strategies (p=0.9039 and p=0.6192, respectively). PVI did not significantly impact deployment or retention rates (p=0.3903 and p=0.0929, respectively).

CONCLUSION

Service members with AF are young with few AF risk factors. Rate and rhythm medical therapies were used evenly. Over two-thirds met retention standards and 40% deployed after diagnosis. There were no differences in deployment or retention between groups who receive rate therapy, rhythm medical therapy or PVI. Prospective evaluation of the efficacy of specific AF therapies on AF burden and symptomatology in service members is needed.

Heart muscle disease management in aircrew

This manuscript focuses on the broad aviation medicine considerations that are required to optimally manage aircrew with suspected or confirmed heart muscle disease (both pilots and non-pilot aviation professionals). ECG abnormalities on aircrew periodic medical examination or presentation of a family member with a confirmed cardiomyopathy are the most common reason for investigation of heart muscle disease in aircrew. Holter monitoring and imaging, including cardiac MRI is recommended to confirm or exclude the presence of heart muscle disease and, if confirmed, management should be led by a subspecialist. Confirmed heart muscle disease often requires restriction toflying duties due to concerns regarding arrhythmia. Pericarditis and myocarditis usually require temporary restriction and return to flying duties is usually dependent on a lack of recurrent symptoms and acceptable imaging and electrophysiological investigations.

An introduction to aviation cardiology

The management of cardiovascular disease (CVD) has evolved significantly in the last 20 years; however, the last major publication to address a consensus on the management of CVD in aircrew was published in 1999, following the second European Society of Cardiology conference of aviation cardiology experts. This article outlines an introduction to aviation cardiology and focuses on the broad aviation medicine considerations that are required to manage aircrew appropriately and optimally (both pilots and non-pilot aviation professionals). This and the other articles in this series are born out of a 3 year collaborative working group between international military aviation cardiologists and aviation medicine specialists, many of whom also work with and advise civil aviation authorities, as part of a North Atlantic Treaty Organization (NATO) led initiative to address the occupational ramifications of CVD in aircrew (HFM-251). This article describes the types of aircrew employed in the civil and military aviation profession in the 21st century; the types of aircraft and aviation environment that must be understood when managing aircrew with CVD; the regulatory bodies involved in aircrew licensing and the risk assessment processes that are used in aviation medicine to determine the suitability of aircrew to fly with medical (and specifically cardiovascular) disease; and the ethical, occupational and clinical tensions that exist when managing patients with CVD who are also professional aircrew.

Congenital heart disease in aircrew

This article focuses i on the broad aviation medicine considerations that are required to optimally manage aircrew ii with suspected or confirmed congenital heart disease (both pilots and non-pilot aviation professionals). It presents expert consensus opinion and associated recommendations and is part of a series of expert consensus documents covering all aspects of aviation cardiology. This expert opinion was born out of a 3 year collaborative working group between international military aviation cardiologists and aviation medicine specialists, as part of a North Atlantic Treaty Organization (NATO) led initiative to address the occupational ramifications of cardiovascular disease in aircrew (HFM-251) many of whom also work with and advise civil aviation authorities.

Contemporaneous management of valvular heart disease and aortopathy in aircrew

Valvular heart disease (VHD) is highly relevant in the aircrew population as it may limit appropriate augmentation of cardiac output in high-performance flying and predispose to arrhythmia. Aircrew with VHD require careful long-term follow-up to ensure that they can fly if it is safe and appropriate for them to do so. Anything greater than mild stenotic valve disease and/or moderate or greater regurgitation is usually associated with flight restrictions. Associated features of arrhythmia, systolic dysfunction, thromboembolism and chamber dilatation indicate additional risk and will usually require more stringent restrictions. The use of appropriate cardiac imaging, along with routine ambulatory cardiac monitoring, is mandatory in aircrew with VHD.Aortopathy in aircrew may be found in isolation or, more commonly, associated with bicuspid aortic valve disease. Progression rates are unpredictable, but as the diameter of the vessel increases, the associated risk of dissection also increases. Restrictions on aircrew duties, particularly in the context of high-performance or solo flying, are usually required in those with progressive dilation of the aorta.