Why auscultate?

Patient assessment is a process of detective work and questioning, observation and investigation. During one case a paramedic may ask the patient many dozens of tailored questions to acquire information about their medical history, presenting complaints, and to assess response to treatment, whilst simultaneously another line of inquiry will be underway to assess the patient’s condition, this time with the body itself providing the answers. It is the aggregation of these various forms of information which together builds the clinical picture from which the likely diagnosis and best route of treatment may be determined. As when building a jigsaw puzzle, the more pieces one has, the sooner and more clearly the image becomes apparent, and when clinical decisions are based upon what is seen in this clinical picture it is of course necessary that those pieces gathered are as useful and reasonably numerous as possible.

Reflecting the central role the cardiovascular system plays in the body and its intimate relationships with other physiological systems, cardiovascular assessment forms much of the overall picture of the patient’s condition. In the prehospital setting this comprises physiological measurements including blood pressure, pulse rate, oxygen saturation, and all aspects of perfusion status, and evaluation of cardiac electrophysiology with 12-lead ECG. Of these however only the ECG looks directly at the function of the heart itself, and even then it is a one-dimensional view. Both electrical and mechanical components of the heart must function correctly for it pump adequately, yet currently paramedics directly assess the electrical activity only, whilst mechanical function is assessed by proxy via other cardiovascular measurements. (Hoit & Walsh, 2011). Cases of pulseless electrical activity (PEA) provide an extreme demonstration of how disparate electrical and mechanical functioning may be, but cardiac auscultation is of better value for reasons other than confirming the obvious when a patient’s beautiful sinus rhythm is not translating to a palpable pulse!

Cardiac auscultation is therefore the assessment tool which links electrical activity with the physical events of every heartbeat, providing valuable information regarding heart structure and function that may not be revealed through other cardiovascular assessments. Whether it is the chronic murmur of a failing valve or the ominous gallop of left ventricular failure that is heard, these easily-gained observations continue to have real diagnostic value even amidst the technology of the emergency department. Despite advances in modern biotechnology, the time honoured skill of cardiac auscultation has repeatedly been shown to reveal pathology not apparent on echocardiogram, as well as providing a second opinion when the döppler returns a false positive. (Chizner, 2008; Uazman, Asghar, Khan, Hayat, & Malik, 2010). Learning to recognise and interpret normal and abnormal heart sounds can expand upon the patient’s medical history and presenting condition, and assist in determining between two differential diagnoses; for example, variability of the first heart sound may aid in discerning supraventricular tachycardia (SVT) with aberrant conduction from the similar and potentially lethal ventricular tachycardia (VT). (Alzad, 2011; Kobza, Roos, Toggweiler, Zuber, & Erne, 2008). 

The skill is interesting and rewarding to develop, informing on hidden aspects of the heart’s physical function much as the ECG reveals secrets of its electrical activity, connecting another piece to the physiological puzzle and providing added perspective to cardiovascular observations. The direct relationship between heart sounds and the cardiac cycle generates a deep understanding of cardiac structure and function, invaluable knowledge also for ECG interpretation and when considering various respiratory disorders, and the wider effects of myocardial infarction. Finally, the need to evaluate heart sounds in the context of the patient’s overall condition reflects and illustrates the impact of cardiac pathology upon the body, such as how a small degree of narrowing in the aortic valve may eventually precipitate heart failure with global effects upon respiratory, renal, and other systems. (Chizner, 2008). Cardiac auscultation is a skill that is gainful both clinically and professionally, and an effective tool when incorporated within systematic patient assessment.

Next: Auscultation techniques.

References

Alzand, B., & Crijns, H. (2011). Diagnostic criteria of broad QRS complex tachycardia: decades of evolution. Europace, 13(4), 465-472.

Chizner, M. (2008). Cardiac auscultation: rediscovering the lost art. Current Problems in Cardiology, 33(7)326-408. 

Hoit, B., & Walsh, R. (2011). Normal physiology of the cardiovascular system. In V. Fuster, Walsh, R., & Harrington, R. (Eds), Hurst's The Heart. (13th ed.). New York, NY: The McGraw-Hill Companies, Inc.

Kozba, R., Roos, M., Toggweiler, S., Zuber, M., & Erne, P. (2008). Recorded heart sounds for identification of ventricular tachycardia. Resuscitation, 79(2), 265-272.

Uazman, A., Asghar, O., Khan, S., Hayat, S., & Malik, R. (2010). Cardiac auscultation: an essential clinical skill in decline. British Journal of Cardiology, 17(1), 8-10.