Finite-Frame Transfer Compatibility: Exact Spectral-Mixing Residuals under Known Circular LTI Transfer Finite spectral estimation and known linear transfer do not generally commute. This work shows that the resulting spectral discrepancy is not merely an uncontrolled finite-window artifact: under a known circular LTI transfer and an exact all-origin finite-frame mixing kernel, the compatibility residual is analytically defined and quantitatively computable without fitted calibration. For an input power spectrum S, a nonnegative finite-frame mixing operator K, and power transfer a=∣H∣2, the fitted log-frequency slope of the compatibility defect is exactly the residual between ideal transfer slope and observed spectral-slope migration on a fixed frequency mask. Its pointwise depth curvature is also determined by a variance of log transfer gain under a depth-tilted spectral measure. The frozen benchmark contains 64 synthetic records and 65 nonoverlapping real-data blocks from electrocardiography, Bitcoin minute returns, and solar-wind magnetic-field data. Across 3483 retained cells, pooled R2 for ΔR4=R4−R3 ranges from 0.9891 to 0.9994 across the nine real dataset–estimator groups. After removing fixed-configuration means, R2 remains 0.6608–0.9943; across 81 fixed real configurations, the median R2 is 0.8782. The record includes the manuscript, frozen data, executed publication run, source code, dependency specification, provenance and licensing documentation, and SHA-256 manifests required to reproduce and audit the reported results. Reproducibility DOI: 10.5281/zenodo.22056027Corresponding author: gmtheory@outlook.fr Licensing is file- and source-specific. See DATA_LICENSES_AND_ATTRIBUTION.md for upstream licenses, attribution requirements, and provenance of the redistributed data.
Lloyd W. Klein, James A. Goldstein, David E. Haines, Charles E. Chambers · 8 authors
Renewed attention has focused on the occupational health hazards posed by working in the fluoroscopic laboratory.1-6 Accumulated occupational radiation exposure is associated with health risks to physicians, nurses, and technologists working in this environment. Health care workers are subject to insidious health effects of radiation exposure over many years. Adverse effects include the established predilection to posterior subcapsular cataracts, as well as worrisome signals of lifetime risks of cancer induction, particularly in the unprotected brain.7-12 A further consequence is the extensively documented incidence of orthopedic illnesses reported in physicians as well as nurses and technologists and injuries linked to the cumulative burden of bearing the weight of only partly protective lead aprons mandatory to reduce radiation risk.13-16 The increased volume and complexity of procedures, together with the physical stresses inherent in procedural performance, have exacerbated the prevalence and magnitude of such orthopedic injuries.17 The high prevalence of orthopedic afflictions not only affects individual health but also could be potential career ending, with workforce implications for both the profession as well as for society.15 Advances in interventional imaging techniques and treatments over the last three decades have achieved significant success with clear benefits to our patients18; yet protective measures for workers have unfortunately lagged the pace, magnitude, and impact of this therapeutic progress. The purpose of this position statement is to review the data documenting occupational health injuries, summarize current equipment and processes that can be widely applied to optimize protection, emphasize the importance of investment by hospitals and health systems in protective equipment established to enhance workplace safety, examine barriers that need to be overcome to spur advances to enhance the occupational safety of the fluoroscopic laboratory environment, and propose enhanced advocacy for innovation. Future processes and proposals to improve the fluoroscopic laboratory environment should be based on the following precepts: (a) there is ample clinical data documenting the prevalence of serious occupational health risks engendered by the fluoroscopic laboratory environment; (b) sufficient attention to these occupational health issues has been drawn in annual meetings and published clinical scientific studies; (c) despite these data and advocacy efforts, advances to improve worker safety in the fluoroscopic laboratory remain inadequate; and (d) a concerted effort by all stakeholders (physicians, catheterization laboratory nurses, and technologists, sonographers, hospitals, professional societies, and industry) in the fluoroscopic laboratory is necessary to further advance occupational safety and health. Radiation exposure is inherent to procedural performance in the fluoroscopic laboratory. Exposure to ionizing radiation imposes health risks to both patients and operators, resulting in an increased likelihood of numerous illnesses and diseases.1-8 The association with posterior subcapsular cataracts is well documented.11, 12 There are growing concerns for cancer induction,7, 8 with recent reports of a cluster of predominantly left-sided brain cancers in interventionists,9, 10 as well as a signal for increased breast19-22 and skin cancers.23-26 Radiation exposure generally, not necessarily as part of occupational exposure, is associated with leukemia/lymphoma, myeloma, numerous gastrointestinal and bone cancers, and thyroid and parathyroid adenomas. These disquieting signals fuel the increasing anxiety regarding radiation exposure-related oncogenesis, though no mortality impact has been proven.27 Recent studies have also suggested that occupational radiation exposure is associated with hypertension, hypercholesterolemia, and possibly atherosclerosis.28-30 Evidence of lengthening sarcomere length and early vascular aging in epidemiologic studies suggests that workers who are occupationally exposed to radiation during interventional procedures may be at increased risk to develop these same illnesses.30, 31 There is now overwhelming evidence demonstrating that working in the interventional laboratory is associated with an increased incidence of orthopedic illnesses, particularly those related to the cervical and lumbar spine. These orthopedic injuries have been linked to the cumulative effects of bearing the weight of leaded aprons.5, 15, 16 Additionally, the design of the catheterization laboratory environment promotes awkward orthopedic ergonomic postures (e.g., monitors placed out of the line of natural working sight views). As procedures become increasingly complex and prolonged, and their volume increase in number, it should not be surprising that interventional practice is attended by a high rate (40–50%) of occupational-induced orthopedic injuries.15-17 Over a career's duration, the likelihood of suffering such illnesses are 2–7 times27, 28 higher than other medical occupations. Studies report substantial differences in orthopedic injuries between those wearing lead aprons working in the fluoroscopic laboratory compared to colleagues working in the same department not working in the fluoroscopic laboratory and thus not bearing the burden of wearing lead aprons.27-29 These occupational-related injuries not uncommonly result in missed days of work, surgery, and, in some cases, curtailed careers. This issue has significant implications for the interventional workforce, particularly in view of the aging of the population and anticipated increased procedural demand concomitant with aging of the operators who pioneered these advances.17, 27-29 These occupational health concerns potentially affect several medical specialties, including cardiologists, radiologists, and surgeons working with fluoroscopy, as well as pain management specialists performing nonvascular fluoroscopic procedures. Importantly, all such issues also pertain to the other personnel who are essential members of the “interventional team” (e.g., nurses and technologists, interventional imagers, and cardiac anesthesiologists) who are exposed to the harmful effects of scattered ionizing radiation.30-33 Electrophysiologists and their team are also exposed to radiologic risks and orthopedic injury34 and perhaps even more so, given the duration of their procedures and lack of upper torso shielding during device cases (e.g., implantable defibrillators and cardiac resynchronization therapy). These issues also have particular importance to women; although radiation effects on the fetus have not been demonstrated, women report concerns for adverse effects during reproduction as an obstacle to choice of an interventional career. These radiation exposure concerns have sometimes been considered a reason for disproportionately low representation of women in the field.35 As noninvasive cardiologists specialized in imaging are now required to guide interventions in the catheterization and electrophysiology laboratories, pursuing career in imaging is no longer radiation free and a safer choice for women. This may result in shifts in gender distribution in various cardiology subspecialties, further impacting strategies to improve diversity and inclusion in out profession. The past three decades have witnessed astounding progress in interventional equipment, technique, therapeutics, and the clinical research that catalyzed these advances. Progress in interventional laboratory protection and safety has comparatively lagged, despite the growing mounting data emphasizing occupational health concerns. A paradigm shift to dramatically improve the occupational safety for all stakeholders in the fluoroscopic laboratory (members of the interventional team, professional societies, hospitals, and industry) is required. In particular, there is an opportunity and obligation for industry and hospitals, who clearly benefit from the workers' commitment to their profession, to play a leadership role in correcting these deficiencies. A template exists based on the collaboration established by recent FDA-led efforts aimed to reduce patient exposure.36 Leveraging the concept and practice of the “Image Wisely” and “Image Gently” campaigns codified by Radiological Society of North America37 and Pediatric Cardiology community38 to minimize radiation exposure to patients, in 2010, the FDA Center for Devices and Radiological Health launched an Initiative to Reduce Unnecessary Radiation Exposure from Medical Imaging. As part of this initiative, the FDA held a public meeting on ways to improve devices to reduce unnecessary radiation exposure to help the agency decide on any new, targeted requirements for manufacturers of computed tomographic and fluoroscopic devices. This effort resulted in an industry-driven enhanced awareness, with mandates to recognize both the needs for and market potential of innovations focused on minimizing patient radiation exposure. These initiatives rapidly resulted in dramatic changes to improve the X-ray systems. Examples of these improvements include minimizing radiation exposure through lower emission X-ray systems as well as monitoring, recording of each procedure's patient exposure, and standardization in laboratory reports and patient charts. These efforts have also stimulated industry to develop X-ray systems that provide high-quality imaging at low-radiation exposure dose levels. Hospitals should be encouraged to invest in adopting such platforms that have potential to mitigate occupational risk. Physicians working with our professional societies should strive to establish a culture of safety encompassing both patients and catheterization laboratory personnel (Table 1). The pathway forward should be focused to assure: (1) consistent application and adherence to established and procedural processes; (2) widespread adoption and utilization of novel commercially available protection systems; and (3) encouragement and support to further develop even more effective equipment and processes that facilitate enhanced safety and protection in the workspace. Our professional societies must support individual physicians, teams, and practices, especially those that are hospital owned. It is critical that clinician leaders speak authoritatively to hospital administration and industry partners regarding these concerns without fear of reprisal; societal support could be influential in these situations. The following specific steps should be endorsed by our professional societies to enhance hospital and physician compliance: Whether or not to comply with appropriate shielding and other safety measures should not be at the discretion of the operator. The imaging team (physician, sonographer, radiologic technologist, physicist, and other medical personnel) should be responsible for developing optimized protocols, implementing regular equipment quality control tests, and monitoring radiation doses to patients and members of the team. This group and their products should be recognized as an essential part of the quality assurance program, present in all laboratories, for emphasizing radiation management. Operator dose is directly proportional to patient dose; thus, reducing the dose to the patient will benefit the operator. Knowledge of radiation and methods to reduce risk should be stressed to all operators who perform fluoroscopically guided interventions, practiced routinely, and all staff educated in these measures and assuring they are adhered. These methods and concepts have been well described previously.1-7 Recently, publications from the Society of Cardiovascular Angiography and Interventions, The Heart Rhythm Society, and the American College of Cardiology/multi-society consensus document18 articulate detailed procedural systems and processes, as well as practical approaches, to assist cardiac catheterization laboratories in establishing optimal radiation safety program. The components of a radiation safety program include essential personnel, radiation monitoring, protective shielding (at minimum strict adherence to protective aprons and leaded glasses), imaging equipment, and training/education.39-41 Fundamental principles of radiation safety teach the tenet that radiation exposure should be “as low as reasonably achievable (ALARA)”, with monitoring to assure individuals do not exceed annual or lifetime “safe limits.” Unfortunately, the term “reasonably achievable” is ambiguous and not actionable, and may unintentionally inhibit innovative strides to improve safety both for patients who require medically necessary procedures and for workers in radiation-exposed environments. The phrase might incorrectly imply that as long as one's exposure is “minimized,” then that is all that need to be accomplished. Rather, the ultimate goal of innovation efforts should strive to achieve a completely safe environment wherein the ultimate definition of ALARA translates to as close to a zero radiation exposure work environment as possible. Meticulous application of established prudent radiation techniques is obvious and essential. Standard shielding combines laboratory based (e.g., movable ceiling suspended and fixed table-side shielding). Personal protective aprons and eyewear should be properly fitted and maintained, and hospitals should finance these protective devices for all of their employees, including trainees. Newer personal protective choices, including two-piece aprons that are much lighter, may be beneficial; accessory sleeves for arm protection are also available. Despite these advances, the orthopedic burden of only partially protective leaded apparel continues. Institutions and operators must partner to develop a program specific for their laboratory that will result in the adoption of appropriate recent innovations to reduce radiation exposure. Strategies should also include usage of adjunctive devices for which there is substantial data documenting their capability to reduce exposure. Specifically, there is now compelling data demonstrating reductions in exposure with accessory drapes42 (Supplementary Tables); such disposable radiation shielding pads should NOT be refused by hospitals due to their expense. The use of leaded caps has been proposed with mixed results regarding reduction in exposure.43, 44 Simple accessory mobile shields afford significant protection to both nurses and technologists45 as well as to the interventional imaging team.30 More expansive and encompassing lead shielding systems are commercially available,46 and there is a need for more clinical research data supporting their capabilities to reduce exposure. Robotic systems developed to enhance procedural performance also provide protection from radiation exposure to the physician and reduce leaded apron orthopedic burden.47 Thus far, robotics has had limited adoption, due mostly to cost considerations but also fear from the loss of a “hands-on” sensibility. In electrophysiology, intracardiac navigation systems48 have shown efficacy to navigate catheters for ablation procedures with lesser exposure. Simultaneously, industry and physicians must partner to expedite development of a fluoroless catheterization laboratory, using echocardiography, magnetic resonance imaging, 3D mapping, or other technologies. Removing the necessity of lead aprons should be the ultimate goal. Although the proximate cause of many orthopedic complications may be wearing lead, there are other important factors, such as screen height and position, and other ergonometric considerations, which may account for much cervical spine pathology.49 This growing portfolio of enhanced/innovative protective technology will continue to yield a growing pipeline of solutions providing optimism for a healthier work environment. Table 1 summarizes the responsibilities of professional societies going forward. A direct role is a necessity to coordinate the policy matters raised in this document. Table 2 lists the specific future directions recommended for all stakeholders to achieve. It is essential to emphasize that the operator has the responsibility to understand how to use protective equipment optimally to minimize exposure to both patients and personnel.50 Education in this area is already part of cardiology trainee education and is tested in certification exams. Nevertheless, formal training for those who are planning to be interventional operators and imagers should be considered, and compliance monitored on site. Real-time radiation dose monitoring should become standard. Further, physicians must accept the challenge to adopt new technologies for the reduction of occupational hazards. Expense is one reason that new innovations are often not adopted, as it is difficult to advocate for expensive nonrevenue-enhancing equipment in the current fiscal environment. Other obstacles to overcome include potential discomfort with the design modifications and the resistance to making changes in familiar techniques even if there are improvements. The question always arises as to “proof” as to whether the changes are really beneficial, which sometimes become a justification to maintain an unsatisfactory status quo. Therefore, it is incumbent on our profession to continue to produce high-quality clinical research that documents the capabilities of novel imaging equipment, protective devices, and processes designed to improve workplace safety and health. As previously discussed, structural heart interventions depend on procedural image guidance/interventional echocardiography using transthoracic (TTE) or transesophageal echocardiography (TEE) in addition to fluoroscopy. Interventional imagers who operate the TTE or TEE probe and echo console are highly exposed to the harmful effects of scattered ionizing radiation. Protection for these workers also needs to be incorporated and mandated.30, 45, 46 Professional societies should develop programs to assist hospitals and health systems to address occupational safety. It is in everyone's interest to assure the health of medical caregivers.17 The establishment of new, and coordination with existing, comprehensive programs for clinician health in the catheterization and electrophysiology laboratories consistent with recommended wellness programs are an opportunity to highlight this problem. This may include an on-site physical or massage therapist, programs for core strengthening and stretching, and improved posture techniques to prevent orthopedic injury.34 Moreover, this issue can be an opportunity for societies to share and collaborate with international colleagues, who face similar problems. Since the inception of radiologic imaging, the biomedical industry has taken primary responsibility for development and refinement of catheterization laboratory equipment with associated financial benefits. As this equipment engenders intrinsic radiation exposure hazards, industry should assume a level of fiduciary responsibility to optimize the safety of the equipment they design and sell. It is our role to communicate the cardiology community's widespread support for innovations and catheterization laboratory design reformation. Though definite progress has occurred in the past two decades, particularly the advent of high-quality X-ray systems that produce high-quality imaging at lower radiation dose, further innovations are needed to achieve maximal operator radiation protection. The goal is a laboratory design that achieves a completely environment that the need for personal protective apparel and the orthopedic progress has been by the FDA to industry and medical to improve equipment and processes designed to achieve radiation exposure to are that efforts can be to enhance operator safety by providing a template by which this may be innovation will be that market are to such of worker health to increase worker is both the to and a workforce (physicians, nurses, and Hospitals and health care systems should recognize that protective equipment and wellness processes to at the of the health of their workers is more it increased more and increased training Hospitals have the responsibility to and assure worker safety and optimal occupational radiation exposure. radiation provide training and monitoring of personnel and It that hospitals have a responsibility for those working in their and an responsibility not only to maintain and present imaging systems but also to catheterization laboratories with the equipment and established to benefits to the safety and of their of the X-ray with of imaging and equipment are the responsibilities of the will if (e.g., Health and might in on these occupational safety issues and issue that require a for of imaging and protective In this of and commitment on the part of hospitals is critical to industry to invest in research and development of in the that there is an and In our professional societies play a role to help establish is considered and necessary for practice in radiation safety and clinician The is not responsible for the or of any supporting by the than should be to the for the
Giulio Conte, Jędrzej Kosiuk, Ștefan Bogdan, Paweł Balsam · 7 authors
Interventional cardiac electrophysiology (EP) includes conventional and complex catheter ablations of cardiac arrhythmias and management of cardiac implantable electronic devices. The Accreditation Committee of the European Heart Rhythm Association (EHRA) has previously provided cardiologists interested in becoming clinical electrophysiologists with specific curricula, defining requirements both for training centres and trainees.1 Indeed, the presence of a structured EP training programme is of utmost importance in order to ensure high-quality training and comply with the requirements. Nevertheless, so far, very little information is available on EP training status across European Society of Cardiology (ESC) member countries.2,3 Therefore, the purpose of this survey was to obtain detailed information on educational EP training in ESC member countries and to assess the need of certification after completing the EP training. The present survey was conducted by the EHRA Young EP Committee from November 2017 to May 2018. Thirty-seven EHRA Young EP National Ambassadors were contacted to complete the survey. They were contacted by e-mail and/or phone and asked to answer a questionnaire containing information on the status of EP training in their specific country. The following parameters were queried: age at the beginning of medical studies, duration of medical studies, age at the beginning of cardiology training, duration of internal medicine training (if any), duration of cardiology training, features of training (duration/type/level/location), research activities performed during training, proportion of subjects performing a training abroad, need for EP and/or cardiac pacing (CP) certification after completing the training, mean number of centres per country accredited for EP/CP training, institution responsible of the certification (EHRA/National Societies/others). A total of 31 EHRA Young EP National Ambassadors completed the survey (84% response rate). Of the respondents, seven were female (23%). They represented the following ESC member countries: Algeria, Austria, Belarus, Belgium, Bosnia and Herzegovina, Bulgaria, Croatia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Israel, Italy, Latvia, Lebanon, Lithuania, Malta, Norway, Poland, Portugal, Republic of Ireland, Romania, Serbia, Slovenia, Spain, Sweden, Switzerland, and United Kingdom. The information provided was based on the National Ambassador’s personal experience or on the mean value of data provided by additional young electrophysiologists who recently completed their training in the country or abroad. Descriptive statistics were analysed using SPSS V.24.0 (SPSS Chicago, IL, USA). Specific features of Cardiology and EP training are listed in Table 1. Mean age at the time of the beginning of medical studies was 19 years, ranging from 17 to 21 years. Mean duration of medical studies was 6 years, typical for ESC member countries. Internal medicine training was required in 27 countries (87%), with a mean duration of 2.5 years (range 6 months to 6 years). The mean age at the end of the cardiology training was 31.6 years, ranging from 27 to 40 years. The mean duration of EP training was 2.5 ± 1.1 years. Structured EP and CP training programmes were offered only in half of countries (49%). The mean number of centres accredited for EP/CP training per country was 10 ± 31 (range 0–149) (Figure 1). A formal EP/CP subspecialization was required in nine countries (29%) and had a mean duration of 2 years. Research activities were requested in about half (48%) of the countries as part of the training. Finally, there was a considerable variability regarding trainees attending an EP training abroad: 55% of the EHRA Young EP Ambassadors declared a rate of less than 20, and 42% of them reported a rate of greater than 50%. Cardiology and EP training features CP, cardiac pacing; EP, electrophysiology. Cardiology and EP training features CP, cardiac pacing; EP, electrophysiology. Number of EP training accredited centres per country. Reported data refer to the number of centres per 10 000 000 inhabitants in each country. Blue colour refers to centres accredited by their national society; red colour refers to EHRA Recognized Training Centres. *Centres with unavailable information. Six ESC member countries (Bulgaria, Estonia, France, Israel, Portugal, Serbia) (19%) require trainees to obtain certification by the respective National Society after their EP/CP training. None of the National Ambassadors reported obligation for the EHRA certification. Nevertheless, most of the EP trainees (72%) voluntarily take the certification exam after finishing their training. The responsible institution covering the costs of the certification was EHRA in 15 countries (68%) and the respective national society in seven countries (32%). This report highlights several features of the status of EP training in the ESC member countries: (i) a relatively high age of trainees initiating an EP training, (ii) high heterogeneity in the type and duration of training offered by each country, (iii) lack of centres offering a structured EP training programme in many countries, and (iv) request of EP/CP certification after completing training only in a minority of centres. All these aspects are of particular relevance when considering the development of structured EP training programmes and the subsequent individual EP career building. In this survey, the mean age of a cardiologist starting an educational EP training programme was 32 years; therefore, the age cut-off for definition of a young electrophysiologist should be defined accordingly. EHRA can play an active and important role in ensuring the achievement of a proper and homogenous EP training level across all ESC countries. Indeed, recently, EHRA supported good educational practices provided by centres by offering training fellowships programmes in EHRA Recognised Training Centres (ERTC). EHRA strives to maintain the highest standards in education and career development. So far, a list of 21 ERTCs using advanced and uniform teaching techniques has been provided. Moreover, EHRA EP training fellowships and proctor programmes have played a crucial role especially in countries with EP under development with a limited access to structured EP training programmes. In addition, EHRA Young EP Committee and the National Ambassadors can have an important role by highlighting potential training obstacles and issues experienced by trainees in each ESC member country, as they are the most involved stake holders in this training process. Finally, obtaining an EHRA certification after completing the training is demanded being a proof of achievement of practical experience and knowledge in cardiac devices and cardiac electrophysiology, and could guarantee high-level competence, knowledge, and skills of the trainees, supporting improved quality arrhythmia healthcare throughout the European countries. Nevertheless, further efforts are needed to continuously improve and develop activities related to EP training and networking within the EHRA Young EP community that will likely contribute to the improvement of the quality of EP training and early career building of young electrophysiologists. Considerable heterogeneity is present across ESC member countries with respect to access and specific characteristics of EP training. EP/CP certification after completing EP training is requested only in a small proportion of countries. However, most of the trainees voluntarily take the certification exam by EHRA or their national societies. Nevertheless, further efforts to harmonize EP training, and certification requirements across ESC member countries are warranted to improve and homogenize EP quality of care. Conflict of interest: none declared.
EXERCISE, SUDDEN DEATH The sudden death of a competitive athlete is a personal tragedy with great impact on the lay and medical communities(26). Sudden deaths in athletes are usually caused by previously unsuspected cardiovascular disease(1,3,6,11,17,23,31,37,41,42,45,57,59,60,61,62,63,65,67). Such an event often assumes a high public profile because of the generally held perception that trained athletes constitute the healthiest segment of our society. The death of a well-known elite athlete often emphasizes this visibility (26,33). Athletic field catastrophes strike to the core of our sensibilities and often galvanize us. They also inevitably raise a number of practical and ethical issues. This statement is a response to these considerations and represents the consensus of a panel appointed by the American Heart Association Science Advisory and Co-ordinating Committee. The panel comprised cardiovascular specialists, other physicians with extensive clinical experience with athletes of all ages, and a legal expert. The panel 1) assessed the benefits and limitations of preparticipation screening for early detection of cardiovascular abnormalities in competitive athletes; 2) addressed cost-efficiency and feasibility issues as well as the medical and legal implications of screening; and 3) developed consensus recommendations and guidelines for the most prudent, practical, and effective screening procedures and strategies (the recommendations are listed at the end of this statement). This endeavor seems particularly relevant and timely, given the large number of competitive athletes in this country, recent public health initiatives on physical activity and exercise, and the staging of the 1996 Olympic Games in the United States. Definitions and Background The competitive athlete has been described as one who participates in an organized team or individual sport requiring systematic training and regular competition against others while placing a high premium on athletic excellence and achievement (37). The purpose of screening, as described here, is to provide medical clearance for participation in competitive sports through routine and systematic evaluations intended to identify clinically relevant and preexisting cardiovascular abnormalities and thereby reduce the risks associated with organized sports. However, detection of a possible cardiovascular abnormality on a standard screening examination is only the first tier of recognition; referral to a specialist for further diagnostic investigation will probably be required. When a definitive cardiovascular diagnosis is made, the consensus panel guidelines of the 26th Bethesda Conference (34) should be used to formulate recommendations for continued participation or disqualification from competitive sports. The current guidelines focus primarily on the potential for population-based screening of high school and collegiate athletes rather than individual clinical assessments of athletes and apply to competitors of all ages and both genders. These recommendations may also be extrapolated to athletes in youth, middle school, and masters or professional sports, and in some instances to participants in intense recreational sports or those engaged in careers concerned with public safety (e.g., firefighters, police officers, and airline pilots). It is also recognized that overall preparticipation screening goes well beyond the considerations described here, which are limited to the cardiovascular system. These recommendations are predicated on the probability that intense athletic training is likely to increase the risk for sudden cardiac death (or disease progression) in trained athletes with clinically important underlying structural heart disease, although at present it is not possible to quantify that risk. Certainly the vast majority of young athletes who die suddenly do so during athletic training or competition(1,41,42,63). Finally, early detection of clinically significant cardiovascular disease through preparticipation screening will in many instances permit timely therapeutic interventions that may prolong life. Causes of Sudden Death A variety of cardiovascular abnormalities represent the most common causes of sudden death in competitive athletes(1,3,6,11,17,23,31,33,37,41,42,45,57,59,60,61,62,63,65,67). The precise lesions responsible for athletic field catastrophes differ considerably with regard to age. For example, in youthful athletes (younger than 35 yr) the vast majority of sudden deaths are due to several congenital cardiac malformations (Fig. 1). Hypertrophic cardiomyopathy is the predominant abnormality occurring in about one third of cases (41,42,63). The next most frequent cause is congenital coronary anomalies, particularly anomalous origin of the left main coronary artery from the right sinus of Valsalva(2,55). These deaths occur most commonly in team sports such as basketball and football, which have the highest levels of participation. Older athletes (35 yr and older) represent a different athletic population because they do not primarily participate in organized team sports but instead focus on individual endeavors such as long-distance running. The vast majority of deaths in middle-aged athletes are caused by atherosclerotic coronary artery disease (59,60,65,67). Because this statement focuses on the cardiovascular evaluation of athletes, other related medical problems that may cause sudden death, such as cerebral aneurysm, sickle cell trait (19), nonpenetrating blunt chest impact (39), and bronchial asthma are not considered here. Issues related to drug screening also are not considered here, although it is known that ingestion of agents such as cocaine may have severe adverse cardiovascular consequences (16,66). Screening for systemic hypertension, although not regarded as an important cause of sudden unexpected death in young athletes (18), has been addressed. Prevalence and Scope of the Problem The design of a screening strategy must take into account the fact that sudden cardiac death in athletes is an infrequent event and that only a small proportion of participants in organized sports in the United States is at risk(5,63). Indeed, each of the lesions known to be responsible for sudden death in young athletes occurs infrequently in the general population, ranging from the relatively common, such as hypertrophic cardiomyopathy (1:500)(32), to the very rare, such as coronary artery anomalies, arrhythmogenic right ventricular dysplasia, long QT syndrome, or Marfan syndrome, for which reliable estimates of frequency are lacking. Therefore, it is reasonable to estimate that congenital malformations relevant to athletic screening probably account for a combined prevalence of approximately 0.2% in athletic populations. The large reservoir of competitive athletes in the United States constitutes a major obstacle to screening strategies. There are approximately 4 million competitive high school-age athletes (grades 9-12) in addition to smaller numbers of collegiate (500,000) and professional (5000) athletes. This does not include an unspecified number of youth, middle school, and masters level competitors, for which reliable numbers are not available. Although the prevalence of athletic field deaths nationally is not known with certainty, it appears to be in the range of 1:100,000 to 1:300,000 high school-age athletes and is disproportionately higher in males(42,63). Among older athletes, available estimates(40,59) suggest that the frequency of sudden cardiac death due principally to coronary artery disease may exceed that of younger athletes (1:15,000 joggers and 1:50,000 marathon runners). Considering such a relatively low prevalence, the heightened awareness and intense interest in sudden death in athletes, often fueled by the news media, are perhaps disproportionate to its actual numerical impact as a public health problem. Ethical Considerations There is general consensus that within a benevolent society there is a responsibility on the part of physicians to initiate prudent efforts to identify life-threatening diseases in athletes to minimize cardiovascular risk associated with sport. Specifically, there also appears to be an implicit ethical (and possibly legal) obligation on the part of educational institutions (e.g., high schools and colleges) to implement cost-efficient strategies to ensure that their athletes are not subject to unacceptable medical risks. Despite sufficient resources, it is recognized that there may not be a high motivation among professional teams or athletes to implement cardiovascular screening. This may be due to the economic pressures inherent in such a sports environment, for which athletic participation is a vocation and financial remuneration is often substantial. The extent to which preparticipation screening efforts can be supported at any level of competitive athletics is mitigated by cost-efficiency considerations, practical limitations, and the awareness that it is not possible to achieve a zero-risk circumstance in competitive sports(30). Indeed, there is often an implied acceptance of risk on the part of athletes. As a society we permit or condone many athletic activities known to have intrinsic risks that cannot be controlled absolutely-e.g., automobile racing or mountain climbing, as well as more traditional competitive sports such as football, in which the possibility of serious traumatic injury exists. It is important to clearly acknowledge those limitations associated with preparticipation screening in order to 1) inform the public, which might otherwise harbor important misconceptions about the principles and efficacy of athletic screening, and 2) offer appropriate guidance to physicians and healthcare workers responsible for screening. Legal Considerations Although educational institutions and professional sports organizations must use reasonable care in conducting their athletic programs, currently there is no clear legal precedent regarding their duty to require or conduct preparticipation screening of athletes to detect medically significant abnormalities. In the absence of binding requirements established by law or by athletic governing bodies, most institutions and teams rely on their team physician or other medical personnel to determine appropriate medical screening procedures. A physician who has medically cleared an athlete to participate in competitive sports is not necessarily legally liable for an injury or death caused by an undiscovered cardiovascular condition. Malpractice liability for failure to discover a latent asymptomatic cardiovascular condition requires proof that a physician deviated from customary or accepted medical practice in his or her specialty in performing preparticipation screening of athletes and that use of established diagnostic criteria and methods would have disclosed the medical abnormality. The law permits the medical profession to establish the appropriate nature and scope of preparticipation screening of athletes based on its collective medical judgment. This necessarily involves the development of reliable diagnostic procedures in light of cost-benefit and feasibility factors. The current guidelines for cardiovascular preparticipation screening of athletes constitute some evidence of the proper medical standard of care; they will establish the legal standard of care if generally accepted or customarily followed by physicians (47) or relied upon by courts in determining the nature and scope of the legal responsibility borne by sponsors of competitive athletes in determining medical fitness. Current Customary Practice Currently there are no universally accepted standards for the screening of high school and college athletes, nor are there approved certification procedures for healthcare professionals who perform screening examinations. Some form of medical clearance by a physician or other trained healthcare worker, usually consisting of a history and physical examination, appears to be customary for high school athletes. Standards may be mandated by state legislatures or left to the individual state high school athletic associations or school districts. However, there is no uniform agreement among the states as to the precise format of preparticipation medical clearances; in fact, 11 states do not have a standard medical form, and five do not even require an examination. Some forms are specific, whereas others require only the signature of a physician to clear an athlete to compete in organized sports. In a substantial minority of states, nonphysician healthcare workers are allowed to perform preparticipation screening: chiropractors (10 states) and advanced nurse practitioners or physician assistants (with or without physician supervision, 15 states). Appropriate models of the preparticipation examination have been developed by a number of medical organizations and investigators (7,8,14,56). Expectations of Standard Screening Preparticipation screening by history and physical examination alone(without noninvasive testing) is not sufficient to guarantee detection of many critical cardiovascular abnormalities in large populations of young trained athletes. Indeed, hemodynamically significant congenital aortic valve stenosis is probably the lesion most likely to be reliably detected during routine screening because of its characteristically loud heart murmur. Detection of hypertrophic cardiomyopathy by standard screening is unreliable because most patients have the nonobstructive form of this disease, characteristically expressed by only a soft heart murmur or none at all(28,29,34,70). Furthermore, most athletes with hypertrophic cardiomyopathy do not experience syncope or have a family history of premature sudden death due to the disease(35,42). The standard personal history conveys a generally low specificity for detection of many cardiovascular abnormalities that lead to sudden cardiac death in young athletes, particularly those associated with symptoms such as chest pain or impaired consciousness. In older athletes, however, a personal history of coronary risk factors and a family history of premature ischemic heart disease can be useful for identifying those individuals at risk. Effectiveness and Limitations of Noninvasive Screening Tests The addition of noninvasive diagnostic tests to the screening process in young athletes clearly has the potential to enhance detection of certain cardiovascular defects. For example, the two-dimensional echocardiogram is the principal diagnostic tool for clinical recognition of hypertrophic cardiomyopathy, demonstrating otherwise unexplained asymmetric left ventricular wall thickening, the sine qua non of this disease(20,28,29,34,70). Screening for hypertrophic cardiomyopathy with DNA testing for a variety of known mutations in genes encoding proteins of the sarcomere is not yet practical or feasible for large populations, given the substantial genetic heterogeneity of the disease (13,58,68). Echocardiography can also be expected to detect other relevant abnormalities associated with sudden death in young athletes, such as valvular heart disease, aortic root dilatation, and left ventricular dysfunction (with myocarditis and dilated cardiomyopathy). However, even such diagnostic testing cannot itself guarantee identification of all important lesions, and some diseases may not be with any screening For example, identification of many congenital coronary artery usually requires a examination that coronary although in young athletes it is possible with to raise a (or even such as the left main coronary artery from the right sinus of right ventricular usually cannot be reliably with and the available noninvasive for this disease is which is both and not universally available issues are important the feasibility of screening large athletic however, in the vast majority of instances financial and personnel are for such In in which the of testing is the responsibility of such as or professional the are probably ranging from to For example, if the of hypertrophic cardiomyopathy in a young athletic population is to be even at it would to detect even one previously Screening that noninvasive testing at have been described however, these efforts have been in and professional for all but Some investigators have an echocardiogram for population screening, limited to and about such public based on efforts usually cannot be because of for the use of available and are to be on a to provide effective screening of all high school and collegiate athletes. important of screening with two-dimensional is the potential for or may from of for left ventricular wall (or particularly large for that require of a diagnosis the of an and such as hypertrophic cardiomyopathy or other Indeed, such clinical cannot be in some and medical for the and by of the and the for may occur because the of hypertrophic cardiomyopathy may not be or in young athletes (younger than 15 yr) with hypertrophic cardiomyopathy, left ventricular may be or and not diagnostic of that disease The has been as a more practical and cost-efficient to routine for population-based screening Indeed, the is in about of patients with hypertrophic is in other lesions such as coronary and will usually identify the important but long QT However, recent that a certain proportion of in with long QT may have or no on the In preparticipation screening the with the echocardiogram because of its of for recognition of structural cardiovascular The also has a relatively low specificity as a screening in athletic populations because of the high frequency of that are associated with the of an heart to In screening large populations of older trained athletes, routine use of testing to detect coronary artery disease is limited by its low specificity and there have been relatively of cardiovascular screening efforts in large athletic of these have noninvasive testing or limited echocardiogram or in high school or collegiate athletes. The populations have in from to athletes, who usually at In definitive of cardiovascular abnormalities These are with the experience in a systematic for preparticipation evaluation of athletes has been in for more than yr on and Sudden cardiac death in young athletes is a of in the suggest that hypertrophic cardiomyopathy is an important cause of sudden death in young competitive athletes from referral populations with hypertrophic cardiomyopathy have It is possible that this circumstance the limited of certain individuals the and to health care and to athletic screening. Indeed, the that a disease such as hypertrophic cardiomyopathy will be clinically detected may be different and athletes. Sudden death on the athletic field is in young of all such The death may be by participation of different training or cardiac Hypertrophic cardiomyopathy is also commonly recognized clinically in These also suggest the possibility that a of from sudden death is in some to available do not provide a to screening based on or The American Heart Association that some form of preparticipation cardiovascular screening for high school and collegiate athletes is and based on and medical Noninvasive testing can enhance the diagnostic of the standard history and physical however, it is not prudent to routine use of such tests as or testing for detection of cardiovascular disease in large populations of young or older athletes. This is based on both practical and cost-efficiency considerations, given the large number of competitive athletes in the United the relatively low frequency with which the cardiovascular lesions responsible for these deaths and the low of sudden cardiac death in the athletic This however, is not intended to all efforts at population screening that may be by individual there is that the use of noninvasive testing in athletic populations in many among substantial numbers of athletes and their as well as from and athletic Indeed, in such a circumstance with a low of disease in the a great that the number of would exceed that of we that a and personal and family history and physical examination to identify (or raise those cardiovascular lesions known to cause sudden death or disease in young athletes is the available and most practical to screening populations of competitive sports of age. Such cardiovascular screening is an and should be for all athletes. that both a history and a physical examination be participation in organized high school (grades through and collegiate sports. Screening should be In an history should be Indeed, this is with procedures that are customary for most high school and collegiate athletes in the United States. However, it is important to that recommendations or requirements by athletic governing regarding the nature and scope of preparticipation medical evaluations of athletes are not among the states, nor can they necessarily be as medically sufficient in many Therefore, because of this heterogeneity in the design and of preparticipation we also a standard for preparticipation medical to guidelines would have a substantial and impact on the health of athletes by the safety of athletic Despite the limitations of the history and physical examination in coronary artery disease in older athletes 35 a personal history of coronary risk factors or a family history of premature ischemic heart disease may be useful for identifying that disease with screening and should be competitive In it is prudent to perform medically testing in older than (and older than who to in regular physical training and competitive sports if the physician coronary artery disease on the of risk or other than and or but Older athletes should also be about cardiovascular symptoms such as chest These guidelines should not a of on the part of medical practitioners or the general public because the standard history and physical examination the to reliably identify many cardiovascular abnormalities. Indeed, it is an that standard athletic screening can reliably most important cardiac Preparticipation sports are at present by or physicians or healthcare workers with different training and may be associated with or of an school, or we that athletic screening be by a healthcare with the medical and to reliably a cardiovascular perform a physical examination, and heart it is that such an individual be a this may not be and certain it may be for an trained nurse or physician to perform the screening examination. In states in which nonphysician healthcare are to perform preparticipation screening, it will be to establish a certification process to in performing cardiovascular examinations. Specifically, athletic screening evaluations should include a medical history and physical examination, artery This examination should be in an to cardiac in a or as part of a school The evaluation should also certain critical to the detection of cardiovascular diseases known to be associated with or sudden cardiac death in athletes. The cardiovascular history should include to determine 1) of chest or as well as and unexplained of or associated with 2) detection of a heart murmur or systemic and 3) family history of premature death or or significant from cardiovascular disease in younger than yr or of the of certain (e.g., hypertrophic cardiomyopathy, dilated cardiomyopathy, long QT syndrome, Marfan syndrome, or clinically important These recommendations are with the awareness that the of some from young athletes may on their level of and Indeed, should be responsible for the history forms for high school athletes. The cardiovascular physical examination should not necessarily be limited 1) in both the and to in heart with left ventricular 2) of the artery to of the 3) recognition of the physical of Marfan and in the As cardiovascular abnormalities are or the athlete should be to a cardiovascular specialist for further evaluation cardiovascular abnormalities should be with to the 26th Bethesda Conference consensus panel guidelines for the of for athletic competition of sudden cardiac death in young competitive athletes based on systematic of athletes in the United primarily from to left coronary aortic arrhythmogenic right ventricular valve coronary artery hypertrophic from with of the American