Auscultation: A Review of Teaching Methods
Andrew S. Mackie, M.D., S.M.
University of Alberta
Heart murmurs are a common reason for referral to cardiologists, particularly among children, and may be the first clue to the presence of heart disease. However, murmur evaluation is a challenging skill that requires substantial practice and clinical experience in order to do well. Auscultation skills among medical students and residents are poor but can be improved with a variety of teaching methods. Auscultation learning can occur at the bedside, in classrooms, in small group seminars, or as an independent exercise using CDs, the Internet, or other sources of heart sounds. No single method has been shown to be superior to others. Challenges with the existing literature include small sample sizes, lack of standardization of learner assessment tools, short durations of follow-up, and evaluations using recorded or synthetic sounds rather than human subjects. Regardless of the teaching method(s) adopted, structured learner evaluation is recommended, as is an emphasis on distinguishing innocent from pathologic heart sounds rather than the subtle characteristics of one pathologic sound over another.
Heart murmurs are the most common clinical problem confronting general pediatricians and family physicians1, and can be heard in at least 50% of children at some point in childhood2. Murmur evaluation is important, as the presence of a murmur may be the first clue to the presence of congenital heart disease (CHD). However, many physicians are uncomfortable with the task of differentiating innocent from pathologic murmurs in children. As a consequence, the presence of a heart murmur is the most common reason for referral to pediatric cardiology clinics. Among adults, murmur evaluation is also an important clinical problem; even in the absence of symptoms, the presence of a murmur may be the first clue to the presence of valvular or congenital heart disease.
Cardiac auscultation is an invaluable skill that requires practice and repeated clinical exposure in order to master. Unlike many concepts taught to medical students and postgraduate trainees, auscultation cannot simply be learned through rote memorization or understanding of physiologic concepts. As a consequence, the task of teaching auscultation is also challenging. No single teaching method has been widely adopted in the medical education community, and there is a paucity of literature comparing different auscultation teaching methods. Further, there is substantial evidence that auscultation skills of medical students3, residents 4-8, and practicing physicians9 are poor, supporting the notion that increasing availability and reliance on medical technology is having a negative impact on clinical skills, despite the perception of physicians that auscultation remains an important skill9. As a consequence, auscultation teaching is becoming an increasingly relevant field and merits ongoing development and investigation.
The objectives of this chapter are to 1) discuss the evidence regarding the effectiveness of “traditional” auscultation teaching methods, 2) describe the evolving role of “novel” teaching tools, and 3) discuss the considerations required in developing an auscultation teaching program.
Part I: Auscultation Teaching: Traditional Methods
Bedside teaching. The opportunity to manage and care for patients remains the raison d’être of most medical trainees and practicing physicians. Experiences gained at the bedside remain an invaluable opportunity to both teach and learn. Advantages of bedside learning include the opportunity to hear “real” as opposed to recorded or computer-generated heart sounds, to immediately compare murmurs and other heart sounds as heard in different auscultatory areas, during different maneuvers (e.g., Valsalva) or in different positions (e.g., left lateral decubitus position), and to place heart sounds in context with other physical findings (e.g., jugular venous distention). Most importantly, bedside teaching most closely approximates the circumstances under which learners will be applying their auscultation skills when confronted with their own patients in the future. However, there are challenges to bedside auscultation learning. These include the difficulty of examining uncooperative patients (e.g., young children), high ambient noise levels, the impracticality of teacher and learner listening simultaneously (unlike recorded heart sounds), infrequent exposure to rare physical findings, and in many settings a high ratio of learners to patients. Ewy and colleagues described their experience with bedside teaching. They reported that less than 50% of time scheduled for bedside teaching was actually spent at the bedside, that faculty members often demonstrated cardiac examination skills without student participation, and that individual assistance with clinical skills was lacking in the experience of 80% of students. Patients who were either unavailable or too frail served as an additional challenge10. For a further discussion on the subject of faculty-observed clinical skills, the reader is referred to a thorough review11.
There is a paucity of literature on the effectiveness of bedside auscultation teaching, independent of the potential learning impact of simply seeing and examining multiple patients during a cardiology, general internal medicine, or general pediatric rotation. Despite this lack of literature, and the barriers to bedside teaching as noted above, this teaching method offers an invaluable opportunity to model communication skills and “bedside manner”. Furthermore, trainees retain information relatively well when it relates to real cases as compared to when they are provided information that is not in the context of actual patients12. As such, bedside teaching and learning should remain a practice that is valued and pursued when the opportunity presents itself.
Classroom teaching. Classrooms offer the setting to teach a large number of learners simultaneously, to provide multiple audio examples of auscultatory findings including rarely heard sounds, and for teacher and learner to hear and discuss sounds at the same time. Classrooms also offer the opportunity to discuss concepts such as the physiologic basis of murmurs, which may provide relevant background prior to patient encounters. However, inherent limitations of the classroom exist. These include the need for specialized equipment such as stethophones to reproduce sounds with satisfactory fidelity, and the lack of “real-life” context such as co-existing physical findings that bedside teaching provides.
Learners at all levels, including practicing physicians participating in continuing professional development (CPD), have been exposed to classroom teaching of auscultation. Ostfeld and colleagues demonstrated an improvement in auscultation skills of 3rd year medical students listening to pediatric heart sounds after a single cardiologist-led teaching session that used a commercially-available CD-ROM13. However it is not known if that intervention led to a sustained improvement in skill level, as students were assessed only two weeks following the teaching session. Classroom teaching using multiple stethophones attached to a single computer has been well received by students and showed similar effectiveness to CD-ROM- based teaching14. Classroom teaching allows for other innovations; Vukanovic-Criley and colleagues successfully incorporated interactive multimedia into the classroom, demonstrating both visual and audible cardiovascular findings with significant pre-post improvement in auscultation skills among medical students (See Multimedia teaching programs, below)15.
Cardiology rotation. Medical students and residents in family medicine, pediatrics, and internal medicine may have the opportunity to participate in a cardiology rotation. This potentially provides concentrated exposure to multiple patients with cardiac physical findings over a short period of time, and the potential to receive bedside teaching from expert examiners. Cardiology rotations should incorporate bedside teaching, but it is worth noting that these learning opportunities are not synonymous; bedside teaching may occur within settings other than cardiology rotations, such as a clinical skills course for medical students; conversely, although cardiology rotations typically offer the learner plenty of auscultation opportunities as part of patient care, they may offer no actual teaching if in a setting where teaching is not a priority.
Cardiology rotations that include a substantial ambulatory (outpatient) component will provide exposure to a greater number of patients and potentially to a greater variety of physical findings than rotations that are inpatient-focused. Unfortunately there is a lack of literature regarding the impact of a pediatric cardiology rotation on auscultation skills, with some data in fact suggesting no substantial benefit6. Internal medicine rotations have also not been associated with a measurable improvement in cardiac examination skills15-17. However, Dhuper and colleagues compared 11 pediatric residents who had completed a cardiology rotation with 10 residents who had not. Using pediatric patients, they found a higher diagnostic accuracy for a pulmonary stenosis murmur and an innocent heart murmur among those in the former group7. Six of seven (86%) third-year residents, all of whom had completed a cardiology rotation, accurately diagnosed an innocent murmur compared to only 1/7 (14%) of 1st year residents, none of whom had completed a cardiology rotation. However, the authors were unable to separate the potential effect of number of years of training from the completion of a cardiology rotation. It may be that simply having greater experience with patient encounters outside of the cardiology rotation resulted in the improved skills among the 3rd year residents.
Mattioli and colleagues evaluated 26 second and third year pediatric residents attending a 4-week cardiology rotation18. Each resident attended cardiology clinic and performed auscultation on at least 50 patients, some with and others without heart disease. Evaluation at the beginning and end of the rotation was performed using recorded human heart sounds. Accurate recognition of the presence of a murmur improved from 66% ± 17% at the beginning of the rotation to only 76% ± 16% at the end of rotation, though this difference was statistically significant. Recognition of an innocent murmur was poor at the pretest (37% ± 33%) but improved modestly to 54% ± 27% at the post-test, also a statistically significant change. Recognition of a pathologic murmur was 75% ± 24% pre- and 84% ± 16% post-rotation (not statistically significant). Residents were considerably better at recognizing the presence of heart disease than the absence of heart disease at the post-test (86% ± 13% versus 59% ± 25%, respectively). This study supports the notion that auscultation skills can be taught in the clinical setting with improvements apparent over a relatively short period of time, but underscores the need to improve the confident recognition of innocent murmurs to ensure appropriate referrals. However, the emphasis on auscultation teaching and learning that existed in this centre at the time of the study may mean that the post-rotation results are better than would be expected of residents undergoing cardiology rotations in other programs. Unfortunately there is often a lack of emphasis on acquiring auscultation skills during cardiology rotations, and an absence of formal auscultation evaluation pre and post, and this reduces the motivation to teach and learn bedside skills.
Compact disks. A variety of compact disks (CDs) have been developed with high-quality recordings of a variety of heart sounds as outlined in chapter 12 on auscultation resources. Like the classroom, these CDs provide the opportunity to listen to a wide variety of heart sounds. However, CDs also afford more flexibility, allowing the learner to listen with multiple repetitions and at a time that is convenient to him or her (for a discussion of the value of repetition, please see “Repetition” below, and chapters 4 and 5). CDs also offer other potential advantages; they allow the learner to interact with text and graphic material in addition to audio material, and to progress at his/her own pace. CDs also reduce the teaching burden for medical school faculty and offer the opportunity for assessment using imbedded quizzes.
Roy and colleagues evaluated the role of Ears OnTM in a group of family physicians9. Ears OnTM (unfortunately unavailable from 2015) includes approximately 250 heart sound recordings, almost all from patients. Following a baseline assessment of auscultation skills, 42 physicians agreed to participate in 9 months of self-study with at least 15 hours of time spent using the CD. Post-intervention evaluation of the 21 participants who returned for repeat testing revealed that 19 had a significant improvement in their ability to correctly identify heart sounds, with an average of 4.3 ± 1.9 correct answers for 12 heart sounds at baseline, compared to 8.0 ± 2.3 correct answers on the post-test. Eleven participants noted that they had used the CD to help resolve clinical problems seen in practice. Of those who did not complete the post-intervention assessment, the most common cited reason was inability to find 15 hours to use the program, reflecting a reality of busy clinicians.
Finley and colleagues conducted a controlled trial of classroom versus Ears OnTM CD-ROM teaching of 2nd year medical students14. Twenty-one students spent approximately 3 hours over 3 days using the CD, followed by a quiz on the 4th day. A similar number of students participated in a 2-hour lecture reviewing 20 cases chosen to reflect the same sounds heard on the CD. The classroom setting involved multiple stethophones attached to a single computer, and was followed immediately by the same evaluation as the CD group. While the classroom group scored higher on unstructured, open-answer questions, equivalent scores were obtained between groups on multiple-choice questions. Both teaching methods were rated highly by students, and while no student had exposure to both teaching interventions, most felt that exposure to a combination of teaching methods would be ideal.
Ears OnTM has also been compared to a cardiology rotation. Mahnke and colleagues6 evaluated residents using Ears OnTM with residents who had no access to the CD but exposure to an outpatient clinic during a 1 month cardiology rotation. Both groups of residents were evaluated before and after these interventions using recorded heart sounds of 5 common clinical scenarios: atrial septal defect, restrictive ventricular septal defect, moderate valvar pulmonary stenosis, bicuspid aortic valve with aortic regurgitation, and an innocent (Still’s) murmur. The authors demonstrated a modest improvement among the Ears OnTM group (21% improvement in accuracy, primarily due to improved recognition of an innocent murmur). There was no pre-post improvement in skills in the resident group that was exposed to the outpatient cardiology clinic. In summary, CDs are a valuable tool for auscultation teaching with demonstrated effectiveness at least equal to that of other traditional teaching methods but with advantages including flexibility of use and imbedded text, graphics, and assessment tools.
Part II: Auscultation Teaching: Novel Methods
Patient simulator. The use of patient simulation devices for learning clinical skills has become commonplace in medical schools. The first mannequin made for teaching cardiac auscultation was introduced in 1968 and named “Harvey.”19 Another such device, HeartLabTM, developed by Dr. Bryan P. Bergeron (Harvard Medical School) in the 1980s, generates synthetic heart sounds that can reproduce an assortment of heart murmurs and other sounds, either singly or in combination20. Like CDs, this technology allows the learner to be exposed to multiple different heart sounds and to hear the same sound repeatedly.
In a relatively large multicentre study of instruction with “Harvey”, comparing fourth-year students completing a four-week cardiology elective with Harvey instruction (n=116) to fourth-year students completing a four-week cardiology elective alone (n=92), Ewy et al. demonstrated that instruction with the patient simulator translated into a slightly higher performance on skills testing with actual patients10. Although the device was viewed very favourably by students and faculty, identified weaknesses included the lack of respiratory sounds and thrills, and the inability to assess the effect of interventions such as the Valsalva maneuver.
Sverdrup and colleagues conducted a randomized controlled trial of patient simulator training using the CardioSim Auscultation System (Cardionics Inc., Webster, TX) versus bedside teaching21. Forty-nine 3rd year medical students, all of whom had already received core cardiology teaching, received either four hours of simulator training or four hours of additional bedside exposure. Students were then evaluated through examination of four patients, approximately 5-6 weeks following these interventions. No difference was found between students who had simulator training versus additional bedside exposure. Unfortunately the study was limited by the lack of a pre-intervention assessment, the small number of patients available for the post-intervention evaluation, and the absence of innocent murmurs in this group.
de Giovanni and colleagues evaluated the Harvey (“high-fidelity”) simulator versus CD-ROM (“low-fidelity”) simulator in a group of thirty-seven 3rd year medical students22. Students received one hour of introductory teaching and then were randomized to 3 hours of either Harvey or CD instruction, both groups receiving identical subject content. Approximately 6 weeks later students were evaluated in an OSCE format using human subjects, rather than recorded sounds. No difference was found in diagnostic accuracy between these two student groups. Assessment of performance with patients is an important strength of this work, as the authors assessed the transferability of auscultation teaching to real-life circumstances. OSCE evaluation also included an assessment of clinical skills by an observer blinded to the type of instruction the student received; again, no difference between clinical skills of Harvey and CD students was observed. These results support the use of lower-cost CDs over high-cost simulators, the former also offering easier access to students. These findings were also consistent with Kneebone, who has argued that “…lower levels of fidelity may reduce technological limitations and cost without compromising outcomes.”23
Multimedia teaching programs. Vukanovic-Criley et al. reported their experience with multimedia teaching programs, which allowed for what they termed virtual patient examinations (VPEs)15. These consisted of actual patients filmed at bedside with integration of recorded heart sounds and visual signals in order to develop eye/ear integration and to more closely reflect the actual process of examining a patient24,25. This teaching intervention was provided in a classroom in which students listened through their stethoscopes, attached to individual speaker pads, while watching a video of a patient being examined or dynamic graphics of cardiac or valvar action. Eight teaching sessions were held over a total of 12 hours. Twenty-four 3rd year medical students assigned to an 8-week internal medicine rotation and receiving this intervention were compared to 58 students experiencing the internal medicine rotation alone, without supplemental teaching. Videos used for testing differed from those used during the teaching intervention. The authors found that the intervention group improved significantly in mean scores pre- versus post-intervention (58.7 vs.73.5, respectively; p=0.0001) whereas the control group did not improve (60.1 pre vs. 59.5 post, p=NS). When retested over a year later, a subset of 8 intervention group students had higher mean scores (83.6) compared to 9 control students (65.0). Sub-scores in inspection, auscultation, and cardiac exam knowledge also improved in the intervention group. This study demonstrated that an innovative curriculum that emphasized not only auscultation but also the visual and timing aspects of cardiac examination resulted in a sustained improvement in cardiac examination competency scores. Further, clinical rotation alone resulted in no measurable improvement in cardiac examination skills. A multimedia computer system by the name of UMedic has also been shown to improve auscultation skills in pre-post testing of senior medical students after two weeks of instruction17. In summary, multimedia programs are an innovative and effective teaching tool.
Electronic stethoscopes. Electronic stethoscopes offer the potential to generate phonocardiograms and spectrograms when used with appropriate software26; these in turn can be viewed simultaneously during auscultation by learners, potentially offering a learning advantage over auscultation alone. Germanakis and Kalmanti reported a small study of 12 final-year medical students who listened to 125 human recordings including phonocardiograms27. Pre-post evaluation demonstrated an improvement in accuracy from 43.6% to 73.7%. However, this study did not compare learning by auscultation alone to learning by auscultation and simultaneous phonocardiogram viewing. Michaels and colleagues demonstrated that detection of S3 and S4 in digitally recorded heart sounds was improved when listeners had the opportunity to both listen to and visually inspect the heart sounds using acoustic cardiographic tracings, compared to auscultation alone28. This was particularly true among more experienced observers. However, this study did not evaluate the potential role of cardiographic tracings as a teaching tool.
Sound analysis software using advanced signal processing technologies has been developed in recent years29. Used with electronic stethoscopes, this technology interprets heart sounds and determines whether or not the auscultation findings warrant further evaluation (i.e., are likely to be pathologic), with the potential to replace or at least serve as an adjunct to the clinician’s ears. However, to date there is limited data to support this capability30. A study of primary-care physicians listening to 100 pre-recorded heart sounds with and without a computer-based decision support system revealed that referral decisions were improved with use of the computer-assisted auscultation31. However, higher heart rates among young children and difficulty sitting still to obtain high quality recordings will likely to continue to pose challenges for this evolving technology, emphasizing the ongoing importance of strong clinical skills.
Repetition. The value of repetition is also covered in Chapters 4 and 5. Briefly, Barrett and colleagues have demonstrated remarkable improvement in the accuracy of heart murmur assessment among 2nd year medical students after listening to 500 repetitions of four heart murmurs (aortic regurgitation, aortic stenosis, mitral regurgitation, mitral stenosis)31. This was true whether these heart sounds were listened to in a monitored setting (i.e., classroom) or in an unmonitored setting (i.e., on their own time) using a CD. Barrett and colleagues subsequently conducted a study of 3rd year medical students undergoing a 1-month ambulatory medicine rotation16. Sixty-five students in the intervention group listened to simulated heart sound recordings on a CD an average of 2.5 times by self-report, resulting in an average of 500 repetitions of each heart sound. Fifteen controls who had the same ambulatory medicine rotation but no CD scored significantly lower on the posttest. In both studies, Barrett demonstrated that accurate recognition of recorded human heart sounds also improved as a consequence of repeated exposure to simulated sounds. However, the transferability of CD repetition to accurate diagnosis when examining human subjects was not assessed.
Personal digital assistants. Investigators at the Medical College of Wisconsin have published their experience with the use of personal digital assistants (PDAs)32,33. Torre used PDAs to capture students’ clinical experience with clinical auscultation during a two-month medicine rotation32 The PDAs also provided educational content regarding the clinical characteristics of common systolic and diastolic murmurs as well as third and fourth heart sounds. Students reported a high frequency of use and satisfaction with the tool; 70% felt that the PDA-based software helped them improve their auscultation knowledge and skills but there was no actual assessment of students either pre or post use of the PDA.
Internet-based methods. A number of auscultation applications have become available to users of “smart phones” that are available via the Internet. At the time of writing, these include “iMurmur 2”, “Stethoscope Expert”, “iStethoscope Pro”, “iAuscultate”, and “Auscultation”. Undoubtedly the number of available applications will increase rapidly in the next few years. In general these applications feature synthetic sounds that, like CDs, can be listened to repeatedly and at the convenience of the learner. To date the learning impact of these applications has not been published.
CD-type programs can also reside on the Internet, further improving availability and flexibility in learning and testing. Other Internet-based tools include podcasts with sounds and commentary34 and an online curriculum that has been developed by Dr. Michael Barrett in conjunction with the American College of Cardiology. The latter is described in further detail in Chapter 4.
Part III: Considerations in establishing an auscultation teaching program
A thorough discussion on the subject of curriculum development is beyond the scope of this chapter. Multiple resources are available, including publications by Prideaux35and Kern36. However, a few considerations are noted below.
An important early step when establishing an educational program of auscultation is to decide what the objectives of the program will be. The objectives may differ depending on the level of the learner (e.g. 1st year medical student versus pediatric resident). Regardless of the trainee experience, a consistent learner objective should be the distinction between innocent and pathologic murmurs rather than the accurate identification of individual pathologic lesions (e.g. aortic stenosis versus hypertrophic cardiomyopathy). The reason for this is that children with suspected pathologic murmurs require referral to a pediatric cardiologist who will make the specific diagnosis. Studies have shown that referral directly to echocardiography with subsequent referral to a cardiologist when the echocardiogram is abnormal is both cost-ineffective37,38 and creates the potential of false negative (or false positive) diagnoses when children are referred to adult echocardiography laboratories39,40. Adults with suspected pathologic murmurs also require further evaluation, either referral to a cardiologist or for echocardiography and to a cardiologist only when the echocardiogram is abnormal. Therefore, as emphasized in the preceding chapter by Dr. Roy, educational programs for non-cardiologists should focus on general aspects of murmur evaluation (present versus absent, innocent versus pathologic) rather than correct diagnosis of a variety of different pathologic murmurs, to avoid unnecessary referral to specialist care18. The subtle aspects of cardiac auscultation are probably relevant in clinical practice only to those undergoing cardiology training.
Once learner objectives have been determined, the issue of when to teach in the curriculum will need to be considered. However, the ideal time to address auscultation teaching has not been addressed to date; likely more than once is needed. An introduction to cardiac auscultation should occur in conjunction with other topics related to the cardiovascular system in the first or second medical year. This provides the student with the necessary background to begin cardiovascular examination and provides relevance to learning cardiac anatomy and physiology. Classroom settings lend themselves well to this initial step of auscultation teaching. Basic heart sounds including normal first and second heart sounds, including physiologic splitting of S2, can be readily covered in this manner. Features that help distinguish innocent from pathologic murmurs can also be covered at this stage. However, the results of classroom auscultation teaching as discussed above, in concert with the poor skills of postgraduate trainees, indicate clearly that classroom teaching alone is insufficient. A structured approach to auscultation teaching should ideally recur in the third or fourth clinical years, when the subject relevance will be reinforced by regular patient contact and examinations. This is probably done best in conjunction with rotations in internal medicine and/or pediatrics. Auscultation teaching at this stage should be accompanied by structured assessment; as discussed in Chapter 3.
The clinical background of teachers is an additional consideration in developing an auscultation teaching program. Although many publications report teaching interventions lead by cardiologists rather than generalists9,14,16,31 sound knowledge and experience with cardiac examination, coupled with a commitment to the subject material and to teaching in general, is more important than the title of “cardiologist” versus “internist” or “pediatrician”. Self-teaching is also important, as the value of repetition demonstrated by Barrett16,31 requires that commitment come from the student him- or herself. Senior residents should also be encouraged to contribute to bedside teaching of more junior learners.
The burden on human and material resources must also be addressed in planning a teaching program. Classroom teaching and internet or CD-based methods allow for a low ratio of teachers to learners and relatively little time commitment from faculty. Bedside teaching, on the other hand, places a significant time burden on clinicians. Simulators are expensive but may be justifiable when used to teach about multiple organ systems and when program coordination allows for use by multiple learners at various levels of training. CDs and other internet-based sounds may have initial costs but these are typically modest relative to sophisticated simulators, and have the advantage of relatively low maintenance costs.
The existing literature of heart sound teaching, as summarized in this chapter, has a number of limitations. These include small sample sizes, lack of standardization of learner assessment tools, short follow-up, and in many studies the use of recorded heart sounds rather than real patients for the post-teaching intervention assessment. Few studies compare one teaching intervention to another, further limiting the ability to make conclusions about one technique versus another. It is therefore unclear whether many teaching methods that use technical devices result in post-intervention improvement because the methods are truly effective, or because the learner is inspired to spend more time mastering the subject (e.g. applying greater effort when listening to patients). CDs, simulators, internet-based devices, and other sources of recorded heart sounds may not include simultaneous lung sounds or allow for effect of change in position or Valsalva maneuver on murmur quality, thereby not reflecting real life. Simulators, though sophisticated and capable of providing some associated ‘physical findings’ often lack thrills and certainly do not provide for training in bedside manner. Finally, a variety of innocent murmurs often heard in children, such as the Still’s murmur and physiologic peripheral pulmonary stenosis, are underrepresented in simulators and other recorded heart sounds.
In summary, auscultation skills in trainees remain poor but can be improved. The most effective teaching method has not been defined; further investigations, ideally assessing transferability to human subjects, are required. The emphasis with any method, particularly with junior learners, should be on normal versus abnormal heart sounds rather than on the subtle characteristics of one pathologic sound versus other pathologic sounds. Repetition is valuable and should be incorporated into all teaching methods
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