Cardiac Auscultation II: Heart Murmurs Flashcards Preview

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Flashcards in Cardiac Auscultation II: Heart Murmurs Deck (31):
1

Genesis of Cardiac Murmurs

  • Cardiac murmurs
  • Reynolds number
  • Turbulence
  • Normal conditions
  • Primary variable affecting Reynolds number

  • Cardiac murmur
    • Sound generated by turbulent flow
  • Reynolds number
    • Re = ( ρ * V * D ) / η
    • ρ = fluid density
    • η = fluid viscosity
    • V = flow velocity
    • D = tube diameter
  • Turbulence
    • When Renylods number > critical value
  • Normal conditions
    • Blood density, blood viscosity, & cardiac geometry remain constant
  • Primary variable affecting Reynolds number
    • Velocity of blood flow

2

Characterization of Murmurs

  • Intensity
    • Loud or soft
  • Timing
    • Systole or diastole
  • Location
    • Aortic, pulmonic, tricuspid, or mitral
  • Radiation
    • To suprasternal notch, axilla, or posteriorly

3

Loudness/Intensity of Systolic & Diastolic Murmurs

  • Systolic murmurs
    • 1/6: barely audible
    • 2/6: quiet but clearly audible
    • 3/6: easily audible
    • 4/6: easily audible w/ palpable thrill
    • 5/6: audible w/ stethoscope barely on chest wall
    • 6/6: audible w/ stethoscope off chest wall
  • Diastolic murmurs
    • 1/4: barely audible
    • 2/4: faint but clearly audible
    • 3/4: easily audible
    • 4/4: loud

4

Systolic Murmurs

  • Systolic ejection murmurs
    • Generation
      • Turbulent flow across the A2 or P2 outflow tracts
    • Contour
      • Crescendo-decrescendo or diamond-shaped
      • Mirrors the acceleration fo blood flow across the valve during systolic ejection
    • Intensity
      • Varies w/ stroke volume or the contractile state of the ventricle
      • Increase during exercise & w/ inotropic agents
      • Augmented w/ longer RR intervals following premature ventricular contractions (PVCs)
    • Stroke volume
      • Affected by changes in diastolic filling time
      • Longer diastolic filling time --> larger stroke volume
    • Onset
      • Separated from S1 by the period of isovolumic contraction
      • Can't be appreciated on auscultation
  • Halo- or Pan-systolic murmurs
    • Generation
      • Flow from a high pressure chamber to a low pressure chamber
      • Ex. mitral & tricuspid regurgitation, ventricular septal defects
    • Contour
      • Rectangular or plateau
    • Onset
      • Begins w/ S1 and may continue up to & through S2
      • Not associated w/ a period of isovolumic contraction

5

Classification of Systolic Murmurs based on Physiologic Mechanism of Production

6

Common Causes of Systolic Ejection Murmurs

  • Forward flow across a normal outflow tract
    • Innocent murmur
  • Antegrade flow across an obstructed left or right ventricular outflow tract
    • Aortic or pulmonic stenosis
    • Sub-valvular membranes
    • Hypertrophic obstructive cardiomyopathy
  • High flow states related to coexisting medical conditions
    • Thyrotoxicosis
    • Anemia
  • High antegrade flow across a non-stenotic valve related to recirculated volume
    • Intracardiac shunts
    • Significant valvular insufficiency or regurgitation
  • Forward flow into a dilated great vessel
    • Uncommon

7

Characteristics of Systolic Ejection Murmurs

8

Effect of Exercise & Isoproterenol on LV Ejection Dynamics

9

Effect of Stroke Volume on LV Ejection Dynamics

10

SEM: The "Innocent" Murmur

  • Common physiologic finding in up to 50% of children
  • Intensity < grade 3
  • Ends before S2
  • Normal physiological splitting of S2
  • Absence of associated diastolic or systolic ejection sounds
  • Absence of latered physiologic conditions that can increase cardiac output
    • Anemia, thyrotoxicosis, high fevers
    • Structural heart disease
    • Abnormal carotid pulse contour

11

Differential Diagnosis of the Innocent Murmur

  • Innocent cardiac murmur: diagnosis of exclusion
  • High output / flow states
  • Atrial septal defect
  • Mitral valve prolapse
  • Mild valvular aortic stenosis
  • Mild valvular pulmonic stenosis
  • Hypertrophic cardiomyopathy

12

SEM: Aortic & Pulmonic Stenosis

  • Contour of aortic & pulmonic stenosis murmurs
  • Mild vs. worsening valvular stenosis
  • A2 & P2 in aortic vs. pulmonic stenosis
  • Calcified valve leaflets in aortic vs. pulmonic stenosis

  • Contour of aortic & pulmonic stenosis murmurs
    • Diamond-shaped (systolic ejection) murmurs
    • Decrease valve orifice --> increase ventricular ejection time --> increase SEM intensity & duration
  • Mild vs. worsening valvular stenosis
    • Mild valvular stenosis: systolic ejection click may be appreciated if the valve leaflets are pliable & noncalcified
    • Worsening valvular stenosis: SEM --> later peaking --> delayed A2 or P2 onset
  • A2 & P2 in aortic vs. pulmonic stenosis
    • Aortic stenosis: narrowing of the S2 split
    • Pulmonic stenosis: widening of the S2 split
  • Calcified valve leaflets in aortic vs. pulmonic stenosis
    • S2 becomes quieter & more muffled
    • Aortic steonsis: outflow tract obstruction --> decreased cardiac output --> decreased antegrade stroke volume --> decreased SEM intensity
    • Pulmonic stenosis: crescendo-decrescendo murmur may continue beyond & approach P2

13

SEM: Atrial Septal Defect

  • In the absence of pulmonary hypertension
  • Auscultatory findings
    • Increased flow across the pulmonic outflow tract
    • If left to right shunt is sufficiently large
    • Increased pulmonic valve ejection time

  • In the absence of pulmonary hypertension
    • Congenital hole in the atrial septum
    • --> LA pressure > RA pressure
    • --> increased blood from from the LA to the right-sided cardiac chambers
    • --> increased antegrade flow across tricuspid & pulmonic valves
  • Auscultatory findings
    • Increased flow across the pulmonic outflow tract
      • Hear early peaking SEM at the LUSB
    • If left to right shunt is sufficiently large
      • Hear diastolic flow murmur across the tricuspid valve
    • Increased pulmonic valve ejection time
      • Hear wide fixed S2 splitting
      • Related to increased forward stroke volume across the pulmonic valve & decreased impedance in the pulmonary vascular bed

14

SEM: Hypertrophic Obstructive Cardiomyopathy (HOCM)

  • Hypertrophic obstructive cardiomyopathy
  • Systolic anterior motion of the mitral valve (SAM)
  • Resulting SEM
  • S4
  • Pansystolic murmur of mitral regurgitation

  • Hypertrophic obstructive cardiomyopathy
    • Abnormal thickening of the ventricular septum
    • --> abnormal anterior motion of the anterior mitral valve leaflet during systole
  • Systolic anterior motion of the mitral valve (SAM)
    • Creates a dynamic obstruction in the LV outflow tract
    • Increases in severity as the diameter of the LV decreases
  • Resulting SEM
    • Mirrors the severity of the dynamic LVOT gradient
    • --> late-peaking SEM heard at the LLSB & the cardiac base w/ radiation to the suprasternal notch
  • S4
    • May be present due to a late diastolic "atrial kick" into a stiff noncompliant LV
  • Pansystolic murmur of mitral regurgitation
    • May be appreciated due to the abnormal coaptation of the mitral valve leaflets during ventricular systole

15

Pan- or Holo-systolic Murmurs (HSMs)

  • General
  • Conditions you can hear this with
  • Auscultatory findings
  • Intensity

  • General
    • Produced by retrograde blood flow from a high pressure chamber to a low pressure chamber
  • Conditions you can hear this with
    • Mitral regurgitation
    • Tricuspid regurgitation
    • Ventricular septal defects
  • Auscultatory findings
    • High pitched
    • "Blowing" quality
    • Rectangular contour
  • Intensity
    • Good correlation b/n the intensity of the regurgitant murmur & the severity of regurgitant flow

16

With arterial vasodilation, a mitral regurgitation murmur would most likely...

Decrease in intensity

17

Paradoxical splitting of the S2 may be associated w/ which of the following conditions:

  • Congenital pulmonic stenosis
  • Atrial septal defect
  • Moderate aortic stenosis
  • RBBB
  • LBBB

LBBB

  • Paradoxical splitting occurs when A2 and P2 are abnormally separated
  • With inspiration, see the split narrow instead of widen
  • A2 migrates beyond P2, so with inspiration, A2 and P2 get closer
  • LBBB: LV contracts later than normal, so A2 migrates beyond P2

18

Which of the following auscultatory findings is most specific for the presence of severe mitral stenosis?

  • Presence of a holosystolic murmur
  • Presystolic accentuation of a diastolic murmur
  • Presence of an S4
  • Narrow S2 opening snap interval
  • Presence of an S3

Presystolic accentuation of a diastolic murmur

19

Effect of Changes in Afterload on Murmur of Mitral Regurgitation

  • Mitral regurgitation
  • Intensity
  • Interventions that increase systemic / LV pressure (increase the pressure gradient)...
  • Interventions that decrease systemic / LV pressure (decrease the pressure gradient)...

  • Mitral regurgitation
    • Retrograde flow across the mitral valve from the high pressure LV into the low pressure LA
  • Intensity
    • Influenced by the pressure gradient driving retrograde flow across the valve
    • Unlike SEMs, pansystolic murmurs vary less w/ changes in RR intervals & alternations in ventricular contractility
  • Interventions that increase systemic / LV pressure (increase the pressure gradient)...
    • Increase MR murmur intensity
    • Ex. handgrip, squatting, & vasoconstrictor drugs like phenylephrine
  • Interventions that decrease systemic / LV pressure (decrease the pressure gradient)...
    • Decrease MR murmur intensity
    • Ex. vasodilator drugs like amyl nitrite

20

Mitral Regurgitation Related to Mitral Valve Prolapse

  • Mitral valve prolapse
  • Auscultatory findings

  • Mitral valve prolapse
    • Abnormally thickened, elongated, & floppy mitral valve
    • Causes mitral regurgitation
  • Auscultatory findings: mid-systolic click
    • Redudant leaflets reach their elastic limits
    • Imperfect coaptation of mitral valve leaflets --> crescendo mitral regurgitant murmur
    • Timing & intensity are affected by loading conditions of the heart

21

Ventricular Septal Defects (VSDs)

  • General
  • Intensity
  • Location

  • General
    • Congenital or acquired
    • Characterized by holosystolic murmurs related to blood flow from the high pressure LV to the lower pressure RV
  • Intensity
    • Inversely related to the size of the defect
    • Smaller defect --> louder murmur
    • Larger defect --> quieter murmur
  • Location
    • Varies depending on the location of the VSD
    • High pressure gradient driving flow --> murmur heard throughout precordium
    • Palpable thrills frequently present

22

Diastolic Murmurs (DM)

  • Diastolic rumble
  • Aortic or pulmonic regurgitation
  • Difference b/n daistolic & systolic murmurs

  • Diastolic rumble
    • Turbulent antegrade flow across the mitral or tricuspid valves
    • Low-pitched murmur
  • Aortic or pulmonic regurgitation
    • Retrograde flow across the aortic & pulmonic valves
    • High-pitched murmur
  • Difference b/n daistolic & systolic murmurs
    • Diastolic murmurs are always indicative of a pathological condition

23

Classification of Diastolic Murmurs Based on Physiological Mechanism of Production

  • Diastolic rumbles are associated with...
  • Diastolic regurgitant murmurs are associated with...

  • Diastolic rumbles are associated with...
    • Turbulent antegrade flow across a stenotic (anatomically narrowed) mitral or tricuspid valve
    • Austin-Flint murmur: physiological impingement of mitral valve diastolic excursion by a severe aortic regurgitation
    • High volume antegrade flow across the mitral or tricuspid valve
      • Associated w/ an intracardiac shunt (ASD or VSD) or significant AV valve regurgitation
  • Diastolic regurgitant murmurs are associated with...
    • Incompetency of the semi-lunar (aortic & pulmonic) valves
    • Dilation of the aorta or pulmonary artery

24

Characteristics of a Diastolic Rumble vs. Semilunar Valve Regurgitant Murmur

  • Diastolic rumbles related to mitral stenosis
    • Onset
    • Auscultation
    • Contour
  • Aortic & pulmonic regurgitant murmurs
    • Onset
    • Auscultation

  • Diastolic rumbles related to mitral stenosis
    • Onset
      • Separated from S2 by a period equivalent to the isovolumic relaxation time/period
    • Auscultation
      • Heard at the LLSB & the apex
      • Louder in early diastole during the rapid passive filling phase of the LV
    • Contour
      • Decrescendos in mid diastole, then crescendos in late diastole w/ the atrial "kick"
  • Aortic & pulmonic regurgitant murmurs
    • Onset
      • Begin immediately after S2 & decrescendo to S1
      • Closely mirror the aortic to LV pressure gradient
    • Auscultation
      • Heard at the cardiac base

25

Diastolic Flow Murmurs Related to Increased Flow

  • Increased flow across anatomically normal valves --> diastolic flow murmurs
  • Most commonly seen in patients w/ intracardiac shunts (ex. ASDs or VSDs)
  • Increased intravalvular blood flow is related to recirculated blood volume from the shunt
  • Similar findings can be seen w/ recirculated blood volume related to severe mitral or tricuspid regurgitation

26

Diastolic Murmurs: Auscultatory Findings Associated with Intracardiac Shunt

  • Atrial septal defects & no pulmonary hypertension
    • Blood is shunted from the LA to the RA --> increased diastolic flow across the tricuspid valve
      • --> soft tricuspid valve diasotle flow rumble
    • Blood volume is ejected across the pulmonic valve
      • --> SEM & wide fixed S2 splitting
  • Ventricular septal defects
    • Blood flows from the high pressure LV to the lower pressure RV
      • --> pan- or holo-systolic murmur
    • Recirculated blood volume courses through the pulmonary vascular bed into the LA & across the mitral valve
      • --> mitral diastolic flow rumble

27

Auscultatory Findings Associated w/ Patent Ductus Arteriosus (PDA)

  • Aortic pressure > pulmonary pressure during both systole & diastole
  • Persistent congenital left to right shunt across the PDA from the aorta to the pulmonary artery
    • --> continuous murmur in the left infraclavicular region or the left 2nd intercostal space
  • Left to right shunt increases pulmonary venous return into the LA & across the mitral valve
    • --> mitral diastolic flow rumble

28

Auscultatory Findings Associated w/ Severe MR & TR

  • Antegrade flow of the recirculated regurgitant volume across the AV valves
    • --> diastolic flow rumbles
  • Large LA blood volume in early diastole
    • --> S3
  • Tricuspid valve pathology
    • Respiratory variation of the systolic & diastolic murmurs

29

30

Aortic & Pulmonic Regurgitant Murmurs

  • Aortic regurgitation
  • Aortic regurgitation auscultation
  • Harvey's sign
  • Afterload vs. aortic regurgitation
  • Pulmonic valve regurgitation

  • Aortic regurgitation
    • Retrograde flow across an incompetent aortic valve
  • Aortic regurgitation auscultation
    • Blowing high-pitched decrescendo diastolic murmur
    • Heard at the 3rd & 4th intercostal spaces
  • Harvey's sign
    • Aortic regurgitation due to dilation of the aortic root
    • Murmur heard along the right parasternal border
  • Afterload vs. aortic regurgitation
    • Maneuvers that affect afterload: hand grip or amyl nitrate
    • Increase aortic diastolic pressure --> increase aortic regurgitant murmur intensity
    • Decrease aortic diastolic pressure --> decrease aortic regurgitant murmur intensity
  • Pulmonic valve regurgitation
    • Graham Steell murmur: associated w/ pulmonary hypertension & a dilated pulmonary artery

31

Other Heart Sounds

  • To-fro murmurs
  • Continuous murmurs
  • Continuous venous hum
  • Mammary souffle

  • To-fro murmurs
    • Aortic stenosis + aortic regurgitation
    • Crescendo-decrescendo SEm + decrescendo diastolic murmur
  • Continuous murmurs
    • Caused by arterial to venous shunts (ex. PDAs, arterial-to-venous fistulas)
    • Characterized by flow that begins in systole & continues through S2 into diastole
  • Continuous venous hum
    • Associated w/ high cardiac output & rapid venous return
    • Heard in the right supraclavicular fossa in children & pregnant women
    • Terminated by compression of the JVP
  • Mammary souffle
    • Associated w/ cardiac output & rapid venous return
    • Related to increased flow in mammary artery & veins
    • Heard in pregnant & lactating females
    • Terminated by compression of the stethoscope against the chest wall