Cardiology - Heart Murmurs

From Iusmicm

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(dRHL0C Im grateful for the article post.Really thank you! Fantastic.)
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=The Approach to Heart Murmurs=
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dRHL0C Im grateful for the article post.Really thank you! Fantastic.
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==Heart Sound Resources==
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*http://www.blaufuss.org
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*http://www.ucla.edu/wilkes/rubintro.htm
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*http://www.depts.washington.edu/physdx/heart/demo.html
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==A Case==
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*You are asked to see a 20 yo man because of a heart murmur discovered during a pre-operative exam. He is to undergo surgery the following day to repair a torn ACL suffered while playing intramural basketball.
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*He has no medical history, has not seen an MD for a few years, takes no medications, and has been physically
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fit his entire life. He cannot ever recall being told he had a murmur.
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*What might be the cause of his murmur?
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*What additional information do you need?
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*What additional tests, if any, would you order?
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*Can he proceed to the OR as planned?
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==Heart Murmurs==
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*Heart murmurs result from '''turbulant flow'''.
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*Turbulant flow can result from:
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**Normal flow over ''abnormal valves''
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**''Increased flow'' over normal valves
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**Normal flow through ''abnormal communications''
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***Especially when the chambers have ''different pressures''
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**Normal flow into ''abnormal, dilated, receiving chamber''
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*Murmurs are '''classified as systolic, diastolic, or continuous.'''
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*Murmurs can be '''normal or life-threatening'''.
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==Characteristics of Murmurs==
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*Characteristics To Be Defined For All Murmurs:
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**Intensity
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**Timing
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**Configuration
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**Duration
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**Location
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**Pitch
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**Radiation
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**Response to provocative maneuvers
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===Murmur Intensity===
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*Intensity is measured in Grades.
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*Grade I: Not immediately audible (that is, cardiologists are the only ones that hear these)
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*Grade II: Heard with each cardiac cycle but not loud
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*Grade III: '''Loud''' murmur '''without a thrill'''
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**Note that Grades II and III are the most common and are often hard to differentiate.
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*Grade IV: Loud murmur '''with a thrill'''
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**Recall that a thrill is a vibration that can be palpated.
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*Grade V: Very loud murmur (rare)
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*Grade VI: May be heard with stethoscope off the chest (very rare)
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===Murmur Timing===
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*Differentiating whether the murmur is during systole or diastole or continuous is important for determining the cause of the murmur.
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*Systolic murmurs include:
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**Systolic ejection murmur
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**Holosystolic murmur
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**Late systolic murmur
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*Diastolic murmurs include:
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**Immediate diastolic murmur (‘early’)
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**Delayed diastolic murmur (‘mid’)
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http://www.vetgo.com/cardio/concepts/images/page29.gif
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===Murmur Comparison===
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{|border=1
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!Murmur type
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!Common causes
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!Benign / Abnormal
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!Anatomy involved
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!Turbulant flow issue
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!Heard during
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|-
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!Systolic Ejection Murmur
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|Anemia, fever, pregnancy, thyrotoxicosis, etc.
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|May be benign
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|Cardiac output tracts (RV, LV, PulmValv, AorticValv, PulmArt, AorticArt)
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|Normal flow, abnormal structure
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|Systole
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|-
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!Holocystolic Murmur
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|Ventricular septal defect, mitral valve regurgitation
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|''Always abnormal''
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|Ventricular septum, valves
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|Abnormal flow, between two chambers of different pressure
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|Systole (including isovolumetric component)
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|-
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!Late Systolic Murmur
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|Mitral valve prolapse / regurg / compensated regurg
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|''Always abnormal''
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|Mitral valve
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|Abnormal flow, abnormal structure
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|Systole
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|-
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!Early Diastolic Murmur
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|Semilunar valve regurgitation
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|''Always abnormal''
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|Semilunar valves (aortic, pulmonary)
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|Abnormal flow, abnormal structure
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|Diastole
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|-
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!Mid (Delayed) Diastolic Murmur
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|AV valve stenosis
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|''Always abnormal''
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|Mitral and Tricuspid valves
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|Abnormal flow, normal structure
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|Diastole
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|-
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!Continuous Murmur
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|PDA, fistula, normal variants
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|Normal or abnormal
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|Ductus arteriosus, fistula
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|Abnormal flow, abnormal structure
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|Holo-cycle
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|}
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===Systolic Ejection Murmur===
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*Systolic ejection murmurs are often '''caused by anemia, fever, pregnancy, thyrotoxicosis, etc.'''.
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*Systolic ejection murmurs ''can be benign.''
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*Systolic ejection murmurs have a '''crescendo-decrescendo''' sound (demonstrated with a diamond shape).
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*Note that '''systolic ejection fraction murmurs commence after the aortic / pulmonary valves open''' and end before systole ends.
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**That is, systolic ejection murmur begins after S1 and the subsequent isovolumetric contraction and ends before S2.
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**Note well that holocystolic murmurs begin ''immediately'' after S1 (within the isovolumetric contraction period) because there is some sort of abnormal communication that doesn't have a nice, normal valve keeping blood from flowing.
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**This makes sense because the murmur is caused by turbulant flow which will begin as soon as the valves open but will end before systole ends (because there is little flow toward the end of systole).
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**http://upload.wikimedia.org/wikipedia/commons/5/5b/Cardiac_Cycle_Left_Ventricle.PNG
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*Systolic ejection murmurs are '''always associated with an output tract of the heart''' and can be '''classified as subvalvular, valvular, and suprvalvular'''.
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*That is, the issue can be in the ventricles (subvalvular), at the pulmonary / aortic valve (valvular), in the pulmonary artery / aortic artery (supravalvular).
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*That is '''systolic ejection murmurs are due to ''normal flow through abnormal structure'''''.
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*Subvalvular systemic ejection murmurs can arise from HCM (hypertrophic cardiomyopathy) or a membrane / tunnel of tissue.
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**http://www.yale.edu/imaging/chd/e_subao_sten/subao_sten_1051809.jpg
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*Valvular systemic ejection murmurs can arrise from '''aortic sclerosis or aortic / pulmonary stenosis'''.
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**Recall that '''stenosis is ''abnormal narrowing''''' whereas '''sclerosis is ''abnormal hardening'''''.
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*The ''duration'' and ''timing'' of systolic ejection murmurs is a function of the intensity and severity of obstruction.
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**Peaking tends to be early in benign murmurs and in aortic sclerosis (abnormal hardening).
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**Peaking tends to be late in severe aortic stenosis (abnormal narrowing).
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===Holosystolic Murmurs===
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*Holosystolic murmurs are caused by '''abnormal flow between two chambers of different pressures'''.
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**Think ventricular septal defect, mitral regurgitation.
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*Holocystolic murmurs are often the '''result of mitral or tricuspid regurgitation'''.
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*The wigger diagram (shape representing sound) for a holocystolic murmur is a flat box spanning the entire systolic segment; this is called '''plateau configuration'''.
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**'''Note well that holocystolic murmurs (unlike systolic ejection murmurs) are heard immediately after S1, during isovolumetric contraction.'''
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**Note that mitral regurgitation causing an holocystolic murmur may not last throughout systole because the left atrial pressure rises quickly during systole such that it will quickly reach equilibrium with the ventricular pressure.
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===Late Systolic Murmurs===
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*The most common cause of '''late systolic murmur''' is '''mitral valve ''prolapse'''''.
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**Recall that prolapse is when the valve is has too much surface area and thus systolic pressure causes the valve to balloon back into the atria.
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**As the valves balloons into the atria, it will eventually (hence the ''late systolic'' aspect of the murmur) allow fluid to  fluid
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*The Wiggers diagram for late systolic murmurs is a late onset bar (representing a click), with crescendo, and sudden stop (no decresendo as with systolic ejection fraction) at the closing of the aortic / pulmonic valve.
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*Mitral valve prolapse and late systolic murmurs are '''often preceded by a mid-systolic click'''
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*'''Late systolic murmurs are always abnormal.'''
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http://upload.wikimedia.org/wikipedia/commons/5/5b/Cardiac_Cycle_Left_Ventricle.PNG
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http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/18148.jpg
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====Hemodynamics of Acute and Chronic Mitral Valve Prolapse====
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*Mitral valve issues include: prolapse, acute regurgitation, and ''compensated regurgitation''.
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*Recall that for a normal mitral valve, there are no murmurs at the S1-S2 (systolic) segment.
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*In ''mitral valve'' '''prolapse''', one hears a '''mid-systolic click''' followed by a '''late systolic murmur'''  (from mitral regurgitation).
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*In '''acute''' ''mitral valve'' '''regurgitation''', one hears a '''loud S1''' (poor mitral valve making lots of noise upon closing), '''explosive systolic murmur''' (because all that pressure forces blood backward into the atrium), and '''an S3 with mid-diastolic murmur''' (because a poor valve means blood leak anterograde during atrial filling).
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**Recall that S3 occurs early in diastole (and S4 is late in diastole, just before S1).
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*In '''compensated''' ''mitral valve'' '''regurgitation''', one hears a '''blowing holosystolic murmur''' and a '''mid-diastolic rumble'''.
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**Note that the LA and LV demonstrate ''increased compliance'' as a mechanism to compensate for mitral regurgitation.
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**This makes sense as a mechanism of compensation because an abnormal portion of the blood in the ventricular lumen is being ejected the wrong way (into the atrium) and ends up as an elevated after-load on the ventricle, thus requiring the ventricle to demonstrate a higher compliance to allow the higher after-load.
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**A similar explanation explains the atrial compliance increase.
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===Immediate (Early) Diastolic Murmurs===
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*Early diastolic murmurs result from semilunar valve regurgitation and are '''always abnormal'''.
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**Recall that the semilunar valves are the aortic and pulmonary (as opposed to the AV valves: mitral and tricuspid).
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*Aortic valve regurgitation murmurs are fast onset at S2, with a decrescendo.
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*The wiggers diagram of aortic regurgitation (early diastolic) murmur is characterized by a sharp onset of murmur at S2 with decrescendo.
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*The '''duration of early diastolic murmurs correlates to chronicity'''.
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**Acute aortic regurgitation will have a short duration ''because the LV diastolic pressure quickly rises to meet the LA pressure during diastole'', thus depleting the pressure gradient that causes flow and noise.
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**Chronic aortic regurgitation will last a longer time because the LV will be dilated (as a mechanism of compensation for the ongoing regurgitation) and thus ''LV and LA pressure will not equilize as quickly'' as before compensation (LV dilation) had occurred.
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*One can '''differentiate between semilunar regurgitation (aortic and pulmonic) by the pitch: aortic regurgitation is a high pitched early diastolic murmur and pulmonary regurgitation is a low pitched early diastolic murmur'''.
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**The only exception to the '''aortic regurge: high pitch, pulmonic regurg: low pitch rule''' is in the case of '''pulmonic HTN which causes pulmonic regurg (an early diastolic murmur) be be high pitched.
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**High pitched pulmonic regurg murmur (as S2 with decrescendo) is called a '''Graham Steele murmur'''.
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====Well-tolerated aortic regurgitation====
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*The longer the early diastolic murmur (that is, the semilunar valve murmur; that is, the aortic regurgiation), the better tolerated.
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**Recall that aortic regurgitation will sound like a '''whispered "R"''' and is '''holosystolic'''.
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*A well-tolerated aortic regurgitation generates a '''visible pulse at the suprasternal notch'''.
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*There is a '''normal upstroke near S1''' with aortic regurgitation.
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*The JVP (jugular venous pulse) is '''biphasic at the supraclavicular fossa in pts with aortic regurgitation.'''
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===Delayed (Mid) Diastolic Murmurs===
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*Just as early diastolic murmurs are due to semilunar valve regurgitation, '''mid-diastolic murmurs are due to an increased flow to valve area ratio (either the valve has stenosed (narrowed) or flow has increased)'''.
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**The cause of mid (delayed) diastolic murmurs is usually mitral or tricuspid regurgitation.
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**However, ''severe aortic regurgitation can cause a mid-diastolic murmur due to premature MV closure'' called an Austin Flint murmur.
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*Delayed diastolic murmurs are ''always abnormal''.
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**Therefore mid-diastolic murmurs are due to '''abnormal flow over normal valves'''.
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**Note that '''mid diastolic murmurs can also be due to
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*The Wiggers diagram for delayed diastolic murmurs is a box ending with a crescendo.
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**The crescendo arises from atrial contraction toward the end of diastole.
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**'''Mid-diastolic murmurs are low pitched.'''
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*'''Mid dastolic murmurs can be heard as an S3 or S4 sound!'''
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**Why does this make sense?
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*Listening for mid (delayed) diastolic murmurs.
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**Recall that early (immediate) diastolic murmurs are from semilunar valve regurgitation.
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**Listening at the Base:
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***Though S1 is best heard at the apex, with AV valve / flow dysfunction, one hears S1 abnormally loud at the base.
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**Listening at the Apex:
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***Listen for a crescendo leading up to S1 (systole).
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***S1 will be very loud (normally loud at the apex, exaggerated in this case due to valve / flow issue).
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***Listen for an (initially) holo-like murmur that occurs late in diastole.
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*Inspection of the mid (delayed) diastolic murmur:
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**JVP is a-wave dominant.
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***Recall that the A wave is usually the greatest amplitude wave as it correlates to systole.
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***In the case of delayed diastolic murmur (dysfunctional AV valve / flow), the other peaks are diminished.
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**The JVP A-wave will occur with a loud S1.
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===Continuous Murmurs===
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*Continuous murmurs occur '''due to flow from high to low pressure throughout the cardiac cycle.'''
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**Common '''causes of holo-cycle flow include patent ductus arteriosus and fistulas.'''
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**'''Normal variations''' that can cause '''continuous murmurs''' include: '''mammary souffle and cervical venous hum'''.
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***Note: "souffle" means the murmur ''has a blowing quality''.
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***Venous hum results from the large volume moving down the jugular veins; usually heard near the clavicle.
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*A Wiggers diagram shows an elongated crescendo-decrescendo (diamond) that '''spans S1-late diastole'''.
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*Continuous murmurs are often '''described as machinery-like and are high-pitched'''.
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**Recall that mid diastolic murmurs are low pitched.
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**Recall that aortic regurg murmurs (an early diastolic murmur) is high pitched.
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**Recall that pulmonary regurg murmurs (an early diastolic murmur) is low pitched (unless accompanied by pulmonary HTN).
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===Murmur Location & Radiation===
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*There are characteristic locations where murmurs of certain anatomical structures are heard.
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*Recall your auscultation landmarks:
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**http://www.med.umich.edu/lrc/coursepages/m1/anatomy2010/html/surface/thorax/heart_label.jpeg
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*'''Aortic valve murmurs''' are usually heard at the RUSB and '''radiate to the carotids or the apex of the heart.'''
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*'''Pulmonic valve murmurs''' are usually heard at the LUSB and '''radiate to the back'''.
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**This makes sense as one recalls the posterior-running aspect of the pulmonary artery as it comes off the right ventricle.
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*'''Mitral valve murmurs''' are usually '''heard at the apex''' and '''radiate to the axilla'''.
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**However, mitral valve prolapse may radiate anteriorly.
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*'''Tricuspid valve murmurs''' are usually heard at the LLSB and ''usually do not radiate''.
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===Dynamic Auscultation===
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*Recall that respiration changes the thoracic pressures and will therefore change murmur sounds.
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*In general: '''right heart murmurs are louder with inspiration''' and '''left heart murmurs are louder during expiration.'''
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**This makes sense as inspiration increases the volume of air in the lungs, forcing blood to the right heart, exaggerating all the right heart murmurs.
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*'''Increasing flow (exercise) generally increases murmur intensity'''
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*Dynamic auscultation can be useful in distinguishing the cause of murmurs.
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*Hypertrophic cardiomyopathy and mitral valve prolapse can
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•Maneuvers to increase LV size:
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-Squatting
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-Isometric hand grip
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-phenylephrine
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•Maneuvers to decrease LV size:
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-Standing
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-Valsalva maneuver
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-Amyl nitrate
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Dynamic Auscultation
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•Hypertrophic cardiomyopathy (HCM)
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-Murmur louder with manuvers that decrease LV size
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-Murmur softer with maneuvers that increase LV size
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•Mitral valve prolapse (MVP)
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-Mid-systolic click earlier and murmur prolonged with
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maneuvers that decrease LV size
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-Mid-systolic click delayed and murmur shortened with
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maneuvers that increase LV size
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Hypertrophic Cardiomyopathy
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http://www.hmc.org.qa/hmc/heartviews/issue9/FOCUS_files/image002.jpg
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Features of a Benign Murmur
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•Grade I-II/ VI early peaking systolic
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ejection murmur (often at LSB)
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•No other abnormalities on CV exam
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•No cardiac symptoms or limitation in
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functional capacity
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•Young patient ( <50)
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•Normal ECG
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•Does not require additional evaluation,
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treatment, or endocarditis prophylaxis
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�
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Revision as of 11:32, 9 March 2012

dRHL0C Im grateful for the article post.Really thank you! Fantastic.

Retrieved from "http://editthis.info/iusmicm/Cardiology_-_Heart_Murmurs"
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