Cardiology - Heart Murmurs

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(Created page with '=The Approach to Heart Murmurs= ==Heart Sound Resources== *http://www.blaufuss.org *http://www.ucla.edu/wilkes/rubintro.htm *http://www.depts.washington.edu/physdx/heart/demo.…')
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=The Approach to Heart Murmurs=
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gESG5b Really informative article post.Really thank you! Want more.
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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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===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 (?) 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
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regurgitation
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Inspection:
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• Carotid pulse
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– visible at suprasternal notch
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– normal upstroke
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– upstroke occurs near S1
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• Jugular venous pulse
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– visible at right supraclavicular
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fossa
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– biphasic
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– displaces neck chain
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Auscultation:
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• EDM is long (holodiastolic)
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• sounds like whispered “R”
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• longer murmur = better tolerated
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�
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Delayed (Mid) Diastolic Murmurs
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A Wiggers Diagram
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�
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Delayed Diastolic Murmurs
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•Also known as ‘mid-diastolic’ murmurs
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•Mitral or tricuspid valve stenosis
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•Severe aortic regurgitation (Austin Flint murmur)
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due to premature MV closure
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•Increased flow across normal valve (ASD)
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•Low pitched
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•Augment in late diastole with atrial contraction
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•Always abnormal
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�
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Patient 05
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Listening at Base:
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• abnormally loud S1 at base
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• shorter S2-OS interval indicates
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severe MS
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Listening at Apex:
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• crescendo, presystolic murmur
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• loud S1
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• S2, OS
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• mid-diastolic murmur
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Inspection:
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• JVP is a-wave dominant
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• a-wave occurs with loud S1
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�
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Continuous Murmurs
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A Wiggers Diagram
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�
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Continous Murmurs
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•Flow from high pressure to low pressure
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throughout cardiac cycle
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•Often high pitched, ‘machinery’ type
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•PDA, fistula
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•Normal variants
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-Mammary souffle
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-Cervical venous hum
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�
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Murmur Location & Radiation
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•Aortic valve usually at RUSB and radiating
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to carotids or apex
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•Pulmonic valve usually at LUSB and may
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radiate to back
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•Mitral valve usually at apex and radiating
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to axilla*
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•Tricuspid valve usually at LLSB
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*Murmur of MVP may radiate anteriorly
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�
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Murmur Loctation & Radiation
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�
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Dynamic Auscultation
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•Respiration
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-Murmurs originating from right heart are louder with
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inspiration and softer with expiration
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-Murmurs originating from left heart louder on expiration
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and softer on inspiration
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•Increasing flow (exercise) generally
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increases murmur intensity
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•Decreasing flow generally decreases
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murmur intensity
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�
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Dynamic Auscultation
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•Useful for distinguishing cause of murmurs
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(Think HCM and MVP !)
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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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�
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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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�
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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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�
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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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Current revision as of 23:23, 1 February 2013

gESG5b Really informative article post.Really thank you! Want more.

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