Brian McCrindle MD, MPH
University of Toronto
Treatises on auscultation, even those within textbooks, have failed to keep pace with advances in technology and contemporary teaching methods. This excellent and timely book sheds new light on how this valuable skill can be taught more effectively. The auscultation of cardiac sounds is deeply rooted in the practice of medicine, representing one of the first amplifications of observation. The critical linkage of observation and pathology was fundamental in elevating medicine from an art to a science. While being seminal in the development of medicine, the long history and many technological advances have left the acquisition and practice of skill in auscultation largely unchanged. This has resulted in a diminishing accuracy of current providers in performing auscultation and interpreting the findings, as expertly outlined in the introductory chapter of this book. The consequence of this lapse in expertise leads not only to missed disease, but to increased costs associated with further diagnostic evalutions for those misidentified as having disease.
How is it that such an ancient and simple practice has survived in the face of escalating technology? The answer is that it remains a relatively simple manoeuvre, which makes it a handy screening and diagnostic tool. Auscultation is often the entry point into more specific diagnostic testing, the results from which then provide the listener with ongoing feedback and skill development. It also allows us as healing practitioners to have direct physical contact with the patient and to peer within. The stethoscope has acquired some of the properties of a talisman, and is often seen as a token of legitimacy of our claim to be health care practitioners, certainly by eager students and novices.
Despite universal use, the utility of auscultation for screening and diagnosis has recently diminished primarily due to failure of educators and mentors to successfully bring the skills of providers to an expert level. There is a wealth of observation by which what we hear has been linked to specific pathology and pathophysiology. Yet diagnostic properties, such as sensitivity, specificity, positive and negative predictive values, likelihood ratios and pre- and post-test probabilities, have not been optimally assessed regarding aspects of auscultation. If auscultation were to be introduced de novo into clinical practice today, we might very well be interested in these properties, particularly regarding the expense in terms of time for skill development and practice versus its utility in the detection and specification of pathology. A few studies have been performed looking at diagnostic testing properties for the differentiation of innocent murmurs from those associated with cardiac pathology, with varying results depending on the type and experience of the specific health care provider group being studied. The results have been a bit discouraging. Some specific auscultatory signs are associated with specific pathologies (eg. pansystolic murmurs associated with ventricular septal defects or atrioventricular valve regurgitation), and thus would be associated with a high sensitivity and specificity when noted. However, individual auscultatory components are rarely considered in isolation. One usually considers the heart sounds, murmurs and extra sounds together, and often in association with other aspects of clinical assessment, such as precordial palpation and medical history. This makes the assessment of diagnostic metrics complex, which lies in contrast to the simple utility of auscultation. Nonetheless, this type of information and a firm evidence base would be very important in informing teaching about auscultation.
The contemporary methods by which auscultation skills might be more effectively taught represent the primary focus of this book. The authors have made careful and expert consideration of novel technology and resources, and state of the art science of education principles specific to auditory learning. Auscultation involves hearing, perception and processing of cardiac sounds, each step of which needs to be specifically addressed and optimized. The conditions, equipment and technique of auscultation can have a great influence on what sounds reach our tympanic membranes. Newer methods have been developed to filter and amplify sounds, as well as to share sounds with multiple listeners and across novel media platforms. This has the potential to provide uniformity in the hearing of sounds. Specific sections of this book address this previously unexplored topic.
However, little has changed regarding how to teach listeners to selectively listen and to focus their perception on individual sounds and components, and then to synthesize that perception into a unified whole. This is the unique and important contribution of this book. The importance of perception is not unique to cardiac auscultation, but has parallels with other endeavours involving complex sound perception, such as speech and music. Evidence and methods from other fields certainly have relevance for auscultation of cardiac sounds, which are as yet an unexplored resource but expertly addressed within this book. The addition of imaging or visual cues may be an important method to augment and focus sound perception. Once perceived, cardiac sounds must be given meaning in terms of their relationship to pathology and pathophysiology. These processing and interpretation steps clearly lie within the realm of clinical teaching, both in didactic formats and in case-based settings. Well-designed and innovative curriculae and a compendium of available resources are needed and provided.
The improvement of teaching methods will lead to the improvement of auscultation skills, which will lead to better detection and differentiation of cardiovascular pathology by a broad range of health care providers, which will further lead to better outcomes for our patients. At each step, evaluation is necessary, and the development of a strong evidence base is critical for ensuring that auscultation continues to have enduring relevance and utility in clinical practice. A comprehensive and informed discourse on this topic is long overdue, and will facilitate innovation in this most fundamental of clinical skills. This book stands alone in the degree to which it comprehensively addresses new technology and new approaches to learning. However, it is not strictly an academic discourse, as much practical material is provided regarding curriculum and available resources. Teaching Heart Auscultation to Health Professionals will ensure that the teaching of auscultation is no longer a skill taken for granted, but an endeavour that is pursued with a high level of expertise and effectiveness.