Relationship between accurate auscultation of the fourth heart sound and the level of physician experience

Beat-to-beat alterations of acoustic intensity and frequency at the maximum power of heart sounds are associated with NT-proBNP levels

Background

Auscultatory features of heart sounds (HS) in patients with heart failure (HF) have been studied intensively. Recent developments in digital and electrical devices for auscultation provided easy listening chances to recognize peculiar sounds related to diastolic HS such as S3 or S4. This study aimed to quantitatively assess HS by acoustic measures of intensity (dB) and audio frequency (Hz).

Methods

Forty consecutive patients aged between 46 and 87 years (mean age, 74 years) with chronic cardiovascular disease (CVD) were enrolled in the present study after providing written informed consent during their visits to the Kitasato University Outpatient Clinic. HS were recorded at the fourth intercostal space along the left sternal border using a highly sensitive digital device. Two consecutive heartbeats were quantified on sound intensity (dB) and audio frequency (Hz) at the peak power of each spectrogram of S1-S4 using audio editing and recording application software. The participants were classified into three groups, namely, the absence of HF (n = 27), HF (n = 8), and high-risk HF (n = 5), based on the levels of NT-proBNP < 300, ≥300, and ≥900 pg/ml, respectively, and also the levels of ejection fraction (EF), such as preserved EF (n = 22), mildly reduced EF (n = 12), and reduced EF (n = 6).

Results

The intensities of four components of HS (S1-S4) decreased linearly (p < 0.02-0.001) with levels of body mass index (BMI) (range, 16.2-33.0 kg/m2). Differences in S1 intensity (ΔS1) and its frequency (ΔfS1) between two consecutive beats were non-audible level and were larger in patients with HF than those in patients without HF (ΔS1, r = 0.356, p = 0.024; ΔfS1, r = 0.356, p = 0.024). The cutoff values of ΔS1 and ΔfS1 for discriminating the presence of high-risk HF were 4.0 dB and 5.0 Hz, respectively.

Conclusions

Despite significant attenuations of all four components of HS by BMI, beat-to-beat alterations of both intensity and frequency of S1 were associated with the severity of HF. Acoustic quantification of HS enabled analyses of sounds below the audible level, suggesting that sound analysis might provide an early sign of HF.

Cardiac Auscultation for Noncardiologists: Application in Cardiac Rehabilitation Programs: PART I: PATIENTS AFTER ACUTE CORONARY SYNDROMES AND HEART FAILURE

During outpatient cardiac rehabilitation after an acute coronary syndrome or after an episode of congestive heart failure, a careful, periodic evaluation of patients' clinical and hemodynamic status is essential. Simple and traditional cardiac auscultation could play a role in providing useful prognostic information.Reduced intensity of the first heart sound (S1), especially when associated with prolonged apical impulse and the appearance of added sounds, may help identify left ventricular (LV) dysfunction or conduction disturbances, sometimes associated with transient myocardial ischemia. If both S1 and second heart sound (S2) are reduced in intensity, a pericardial effusion may be suspected, whereas an increased intensity of S2 may indicate increased pulmonary artery pressure. The persistence of a protodiastolic sound (S3) after an acute coronary syndrome is an indicator of severe LV dysfunction and a poor prognosis. In patients with congestive heart failure, the association of an S3 and elevated heart rate may indicate impending decompensation. A presystolic sound (S4) is often associated with S3 in patients with LV failure, although it could also be present in hypertensive patients and in patients with an LV aneurysm. Careful evaluation of apical systolic murmurs could help identifying possible LV dysfunction or mitral valve pathology, and differentiate them from a ruptured papillary muscle or ventricular septal rupture. Friction rubs after an acute myocardial infarction, due to reactive pericarditis or Dressler syndrome, are often associated with a complicated clinical course.During cardiac rehabilitation, periodic cardiac auscultation may provide useful information about the clinical-hemodynamic status of patients and allow timely detection of signs, heralding possible complications in an efficient and low-cost manner.

Implementation and assessment of a curriculum for bedside ultrasound training

OBJECTIVES

This study assessed a curriculum for bedside ultrasound (US) and compared outcomes from 2 common training pathways.

METHODS

The program consisted of e-learning paired with expert-led hands-on training administered to pulmonary/critical care and cardiology fellows with no prior formal training in bedside US. This "simulation-based learner" group completed a survey of attitudes and confidence before and after training, and knowledge and skills were assessed after training. The surveys and scores of the simulation-based learners were compared to the scores of "experts," who were US-trained emergency physicians, and "apprentice learners," who were intensivist physicians informally trained in bedside US on the job during fellowships.

RESULTS

There was a significant difference in the self-reported level of prior training between the groups (simulation-based learners, 2.8; apprentice learners, 3.7; experts, 4.1, on a scale of 1-5 [P= .02]) but no difference in the interest level or perceived importance of bedside US. The study curriculum was successful, as shown by scores that exceeded the comparison groups in the cardiac and pulmonary courses (cardiac: simulation-based learners, 80%; apprentice learners, 73%; experts, 62% [P= .001]; pulmonary: 84%, 75%, and 72%, respectively [P =.02]). The simulation-based learners gained confidence in skills, whereas the comparison groups lost confidence after testing (P < .005); however, the simulation-based learners gained confidence in US subject areas that were not taught (abdomen [P <.002] and miscellaneous [P =.005]).

CONCLUSIONS

The simulation-based learner curriculum resulted in comparable or greater knowledge and confidence in each area of US versus the comparison groups. Findings of overgeneralization of confidence highlight the importance of quality assurance and supervision in bedside US training programs.

Comparing the auscultatory accuracy of health care professionals using three different brands of stethoscopes on a simulator

Background

It is considered standard practice to use disposable or patient-dedicated stethoscopes to prevent cross-contamination between patients in contact precautions and others in their vicinity. The literature offers very little information regarding the quality of currently used stethoscopes. This study assessed the fidelity with which acoustics were perceived by a broad range of health care professionals using three brands of stethoscopes.

Methods

This prospective study used a simulation center and volunteer health care professionals to test the sound quality offered by three brands of commonly used stethoscopes. The volunteer’s proficiency in identifying five basic ausculatory sounds (wheezing, stridor, crackles, holosystolic murmur, and hyperdynamic bowel sounds) was tested, as well.

Results

A total of 84 health care professionals (ten attending physicians, 35 resident physicians, and 39 intensive care unit [ICU] nurses) participated in the study. The higher-end stethoscope was more reliable than lower-end stethoscopes in facilitating the diagnosis of the auscultatory sounds, especially stridor and crackles. Our volunteers detected all tested sounds correctly in about 69% of cases. As expected, attending physicians performed the best, followed by resident physicians and subsequently ICU nurses. Neither years of experience nor background noise seemed to affect performance. Postgraduate training continues to offer very little to improve our trainees’ auscultation skills.

Conclusion

The results of this study indicate that using low-end stethoscopes to care for patients in contact precautions could compromise identifying important auscultatory findings. Furthermore, there continues to be an opportunity to improve our physicians and ICU nurses’ auscultation skills.

Comparison of auscultatory and echocardiographic findings in healthy adult cats

OBJECTIVES

This pilot study was performed to investigate murmur prevalence and to explore the association between auscultatory and echocardiographic findings in apparently healthy cats in order to design a larger study.

ANIMALS, MATERIALS AND METHODS

Adult cats in 4 rehoming centres were screened by auscultation and echocardiography (echo) over 2 periods of 2 weeks each. In the first period, echo was attempted only in cats with murmurs. In the second period, all cats underwent auscultation by 2 observers and echo. LVH was defined in 5 ways: maximal diastolic left ventricular (LV) wall thickness ≥ 6 mm or ≥ 5.5 mm with 2D (LVH(6 2D), LVH(5.5 2D), respectively) or M-Mode echo (LVH(6 MM) or LVH(5.5 MM) respectively), or LV wall thickness ≥ 6 mm (2D) for >50% of a wall segment (LVH(50%)).

RESULTS

67/199 (34%) cats had a murmur. Interobserver agreement on murmur presence was moderate (κ 0.47). 61 cats with a murmur and 31 cats without underwent both auscultation and echo. Depending on the criteria, LVH was present in 31 (LVH(6 2D)), 21 (LVH(50%)) and 11 (LVH(6 MM)) scanned cats. 18-62% of cats with murmurs had LVH, depending on the echo criteria used. Agreement was best between observers in identifying LVH using LVH(6 2D) and LVH(50%) (κ = 1.0).

CONCLUSIONS

Heart murmurs are common in apparently healthy cats. The prevalence of LVH varies depending on the criteria used.