IN the United States, intraoperative echocardiography (IOE) has become integral to the care of many cardiac surgical patients. Morewood et al. 1surveyed all active members of the Society of Cardiovascular Anesthesiologists (SCA) residing in the United States or Puerto Rico and reported that 94% of respondents practice at institutions that use IOE. Furthermore, 72% of anesthesiologists working at such institutions responded that they personally used transesophageal echocardiography during anesthetic care. Additional findings from this interesting study included that most anesthesiologists did not benefit from formalized training in echocardiography during residency but acquired the skills and knowledge necessary to apply IOE through a variety of personal initiatives. For nearly 50% of respondents, direct economic benefit was not the primary motivator because they never or seldom billed for the procedure. These are remarkable observations. The assimilation of such a complex technology into the practice of cardiac anesthesiology is a noteworthy success for the subspecialty and a testimonial to the hard work of many of its practitioners.
The following paragraphs explore why IOE is applied so widely and why anesthesiologists have become its dominant practitioners. Current issues in the practice of IOE and the response of national organizations will also be discussed. Finally, the potential impact of developments in echocardiographic technology on the practice of anesthesiology in general will be considered.
Intraoperative echocardiography is widely used because it is perceived to provide information that significantly influences clinical management and improves patient outcome. Although there is limited scientific evidence to substantiate such perception, several recent case series have documented the usefulness of IOE in adult and pediatric cardiac surgery. 2–10While none of these reports would withstand rigorous scientific scrutiny, they confirm the clinical opinion that IOE provides new information about cardiac pathology in a significant number of patients (12.8–38.6%) and that the new information results in frequent management changes (4.4–14.6%). Most physicians who care for cardiac surgical patients believe these benefits to be real and have adopted the technique in their clinical practice. An additional factor in favor of IOE is that its risks are low. Kallmeyer et al. 11reported no mortality and a morbidity of only 0.2% in a case series of 7,200 cardiac surgical patients.
Why anesthesiologists? The most obvious explanation is that anesthesiologists are readily available in the operating room, whereas it is a significant inconvenience for many cardiologists to be called, at a moment’s notice, into an unfamiliar environment. This may be particularly true in the United States, where recent changes in healthcare reimbursements have dramatically increased production pressures for all physicians. However, physical presence alone does not explain the dominant role of anesthesiologists. Intraoperative echocardiography requires immediate and definitive interpretation, with little room for error. It is certain that repeated misinterpretations by anesthesiologists would be challenged. Therefore, most cardiac anesthesiologists must have either acquired sufficient skills to consistently provide correct interpretations independently, have developed support systems that are adequate to assist them when in doubt, or both. The survey of Morewood et al. 1suggests that both approaches are being followed. Anesthesiologists are the primary providers of IOE because they are physically present and are competent to do so.
Although the survey highlights the successes of anesthesiology in IOE, it also points to a number of areas that require further attention. 1It is alarming that 50% of anesthesiologists almost never write a formal report of the IOE findings in the patient’s chart. In the American Society of Anesthesiologists/SCA Practice Guidelines for Perioperative Transesophageal Echocardiography, the ability to communicate the results of a transesophageal echocardiographic examination to the patient and to other healthcare professionals and to summarize these results in the medical record was listed as an essential basic skill. 12The reasons for considering such a skill essential are obvious. Because the IOE information is used to influence patient management, it belongs in the patient’s permanent medical record. The patient and other healthcare professionals should be able to access it readily for future reference. The failure to report IOE results consistently significantly diminishes the credibility of anesthesiologists as echocardiographers. To facilitate and encourage reporting, a task force of the SCA and the American Society of Echocardiography (ASE) has designed a sample report. It is currently available on the Web. *
The survey also documents that training and credentialing continue to be difficult issues. 1Fortunately, professional organizations are attempting to provide direction. An SCA/ASE task force is currently developing training guidelines for IOE. The guidelines will recommend specific training components and duration of training for two levels of training: basic and advanced. 12The task force’s guiding principles are that residents in anesthesiology should be able to meet the training requirements for basic perioperative transesophageal echocardiography before completion of the Clinical Anesthesia-three (CA-3) year, whereas the requirements for advanced training should be achievable during a year of fellowship in cardiothoracic anesthesiology. Physicians already in practice would be advised to acquire equivalent, supervised experience in their own practice environment.
It is surprising that only 214 respondents indicated successful completion of the certification examination in perioperative transesophageal echocardiography of the National Board of Echocardiography (NBE). 1The test has been administered annually since 1998, and currently, 955 physicians have passed the examination. The discrepancy between the actual certification rate and the survey’s findings is mostly due to the timing of the survey; the results of the 2000 and 2001 examinations could not be included. To a much smaller degree, it is due to the certification of non-US residents, non-SCA members, or nonanesthesiologists. Although few institutions currently consider the NBE examination when credentialing in IOE, this may change when the NBE proceeds with a formal board certification process. When training guidelines have been published, the NBE intends to recognize physicians who have met both training and examination requirements as Diplomates of the NBE.
Advances in technology have promoted the widespread application of echocardiography. Today, echocardiographic images have become crystal clear, and intracardiac flows can be measured with great accuracy. Real-time automated border detection and tissue Doppler imaging impart new insight into systolic and diastolic function and the temporal components of myocardial ischemia. Even more astonishing technical developments are just around the corner. Real-time, four-dimensional echocardiography is almost ready for clinical trials. In this amazing technique, high-resolution three-dimensional images of cardiac structures can be viewed from any angle or through any cross-section over time (fourth dimension). For example, three-dimensional images of a mitral valve can be rotated to visualize either its atrial or ventricular surface, and details of interest can be examined in any cross-section, all in real time. This is truly revolutionary. The list of other exciting new developments is long and beyond the scope of this discussion.
However, one technical novelty is especially noteworthy because it may markedly influence the practice of anesthesiology and perioperative medicine. During the past year, handheld echocardiography devices have become available. They usually weigh less than 3 kg and cost less than $20,000. Their capabilities are still somewhat limited but have been found adequate in preliminary reports. 13–15These handheld devices will extend the role of echocardiography well beyond the echocardiography laboratory or cardiac operating room into many areas of perioperative care, such as preoperative evaluation, noncardiac surgery, and postoperative management. Their introduction into perioperative care will require huge efforts in training and assimilation, but the practice of perioperative medicine will be inconceivable without their use. In the near future, anesthesiologists will need to become as comfortable with the handheld echoscanner as they are with the stethoscope. This is a significant challenge, but if history is a guide, it is a challenge that anesthesiology can face with confidence.