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CAP101 - p7 - Murmurs and miscellaneous

Page history last edited by Hypocaffeinic 10 years, 8 months ago

Murmurs & miscellaneous

 

 

Murmurs

 

Smoothly flowing liquids create no noise, and generally the flow of blood through the normal, healthy heart is near silent. When this flow is disrupted the resultant turbulence produces heart murmurs that may signify structural pathology. These structural causes of murmurs may be congenital, such as ventricular septal defects; chronic, such as aortic stenosis; or an acute change resulting from myocardial infarction, such as mitral regurgitation. (Walsh, O'Rourke, & Shaver, 2011). As the variety of murmurs and their underlying pathology is enormous, and much of it is outside the scope of this course and paramedic practice in general, this page will outline the main categories of murmurs before discussing mainly the murmur most relevant to prehospital cardiac emergencies.

 

Murmurs in general produce prolonged sounds which may be present during either the systolic or diastolic phases, or across both to varying degrees. They are usually consistent in quality and timing from beat to beat, and are categorised and described according to their timing, quality, pitch, and auscultation location. Many murmurs are caused by valvular dysfunction, and as with heart sounds the timing and quality of the murmur gives clues as to its origin; for example, a strong whoosh heard at the aortic and apex sites during early systole may indicate aortic stenosis, where the narrowed valve ejects a jet of blood under high pressure during ventricular contraction. (Lilly & Jung, 2011; Walsh, O'Rourke, & Shaver, 2011). 

 

 

Common heart murmurs and location

 

(Lilly & Jung, 2011a).

 

 

Mitral regurgitation

 

Perhaps the most important murmur to recognise in the prehospital setting is acute mitral regurgitation, associated with left ventricular myocardial ischaemia and inferior infarction. In such cases the mitral valve does not close fully during ventricular systole, allowing regurgitation of blood under high pressure back into the left atrium. Mitral regurgitation is heard as a pansystolic sound, spanning the entire systolic phase of the cardiac cycle, and is seen with rapid onset of acute pulmonary oedema and signs of congestive heart failure. (Chizner, 2008).


The cause of valve failure is ischaemic injury to the papillary muscles which anchor the mitral valve flaps to prevent prolapse during the extreme pressures of ventricular systole. This may cause partial or complete rupture of the papillary muscle or chordae tendinae, often linked to obstruction to the posterior descending coronary artery in inferior myocardial infarction. Papillary muscle rupture with acute mitral regurgitation accounts for 5% of deaths in acute coronary syndrome, and requires urgent surgical repair. (Hass, Yang, Gersh, & O'Rourke, 2011).

 

The following are sound files of mitral regurgitation: note where the murmur is heard in the cardiac cycle, exactly between S1 and S2 during the systolic phase only. Particularly interesting is the recording of mitral regurgitation with S3, indicating the advanced congestive heart failure in this patient that near inevitably results from mitral valve failure. 

 

Mitral Regurgitation by Hypocaffeinic 

 

 

More on murmurs

 

Murmurs are described according to similar measures as for heart sounds - timing, intensity, pitch and quality, location and radiation, and their response to physiological adjustments such as postural changes or the respiratory cycle. The intensity of murmurs is further graded, from barely audible to a volume so loud that they may be auscultated with the stethoscope held off the patient's chest, and palpated upon the skin. (Lilly & Jung, 2011b). The following videos present information on the various attributes of murmurs, and demonstration cardiac auscultation of murmurs. 

 

        

(ProfHeaslip, 2001a, 2001b)

 

 

This is an audio set comprising many different murmurs for your interest, including an unidentified murmur.

 

Miscellaneous Murmurs by Hypocaffeinic

 

 

Pericardial pathologies

 

Should the pericardial sac that supports and protects the heart become inflamed, either due to infective or idiopathic processes, it may become thickened and less compliant than normal. The pericardium may rub against the heart as it beats, creating an audible sound that may still remain if pericardial effusion develops which increases the fluid within the sac. These rubs are audible at certain stages of the cardiac cycle, and have a rough quality that is likened to dry leather or scratching sounds. If pericardial effusion is extensive however, all cardiac sounds may be diminished. (Walsh, O'Rourke, & Shaver, 2011).

 

As the heart beats the motion creates a rub pattern that is recurrent in certain parts of the cardiac cycle. Whilst the quality of the sound may change from beat to beat, a characteristic that is quite diagnostic for pericarditis, the timing generally remains consistent. The sounds are best heard in the 5th intercostal space at the sternal border and apex, with the patient leaning forwards and breath held at the peak of expiration. (Chizner, 2008). Pericardial rubs may present with two or three components as demonstrated in the following audio files.

 

  Pericardial Pathologies by Hypocaffeinic 

 

 

 

Next: Assessment.

 

 

References

 

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

Hass, E., Yang, E., Gersh, B., & O'Rourke, R. (2011). ST-segment elevation myocardial infarction. In V. Fuster, Walsh, R., & Harrington, R. (Eds.), Hurst's The Heart. (13th ed.). New York, NY: The McGraw-Hill Companies, Inc.

Lilly, L. & Jung, H. (2011a). Locations of maximum intensity of common murmurs [Image]. In L. Lilly (Ed.), Pathyphysiology of Heart Disease. (5th ed.). Baltimore, Maryland: Lippincott Williams & Wilkins.

Lilly, L. & Jung, H. (2011b). The cardiac cycle: mechanisms of heart sounds and murmurs. In L. Lilly (Ed.), Pathyphysiology of Heart Disease. (5th ed.). Baltimore, Maryland: Lippincott Williams & Wilkins.

ProfHeaslip. (2011a, Jun 7). 10-Attributes and grading of murmurs [Video file]. Retrieved from http://www.youtube.com/watch?v=Ap5Y-vbNcI8

ProfHeaslip. (2011b, Jun 7). 11-Auscultation of murmurs [Video file]. Retrieved from http://www.youtube.com/watch?v=bKncfXsCex0

Walsh, R., O'Rourke, R., & Shaver, J. (2011). The history, physical examination, and cardiac auscultation. In V. Fuster, Walsh, R., & Harrington, R. (Eds.), Hurst's The Heart. (13th ed.). New York, NY: The McGraw-Hill Companies, Inc.

 

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