Heart murmurs

Question 1

Cause of murmurs

Answer 1

• Arise from turbulent flow
  o Viscosity mostly determined by PCV
  o Turbulent flow can result from 2 main factors:
   High velocity → ↑ volume or narrow valve
• Murmurs from increased blood flow are usually low intensity
   Low viscosity w normal velocity

Question 2

Reynolds #

Answer 2

Reynold’s number = (radius x velocity x density)/viscosity

Question 3

Description of HM

Answer 3

o Anatomic location: PMI
o Intensity, pitch
 High >300Hz
 Mid 100-300Hz
 Low <100Hz
o Timing: systolic, diastolic, continuous
o Duration w/i cardiac cycle: holo/pan, proto/meso/tele
o Quality: shape on phonocardiogram
 Plateau: equal intensity
 Decrescendo: gradually taper off from initial peak
 Crescendo-decrescendo (diamond-shaped): build to a peak and gradually diminish

Question 4

Systolic murmurs

Answer 4

Ejection
Regurgitant

Question 5

Characteristics of ejection murmur

Answer 5

• Crescendo-decrescendo: ↑ intensity to peak in early-mid systole, then decreases and end before S2
• ↑ severity of lesions: louder murmurs w delayed peak
  o If not associated w dynamic obstruction: shorter, softer, protosystolic

Question 6

Causes of ejection murmur

Answer 6

o LVOTO (SAS, HCM)
o RVOTO (PS, TOF)
o Hyperkinetic/high flow states (anemia, hyperT4, fever)
o Functional/flow murmur:
 Young: size of Ao/PA vs high CO
 DRVOTO or DLVOTO
o Other:
 Ao/PA dilation distal to valve
 Degenerative changes to Ao w/o significant stenosis

Question 7

Physiological ejection murmur: most commonly seen

Answer 7

young animals
o No structural dz
o Physiologic murmur: ↑CO, ↓ blood viscosity
o Typically disappear in early adults

Question 8

Physiological ejection murmur: features

Answer 8

• Usually soft (grade I or II/VI), early-mid systolic, high frequency
  o Character can change w body position, HR
  o DRVOTO common in cats = little clinical consequence
• Basilar: loudest at AoV or PV
  o Do not radiate

Question 9

Physiological ejection murmur: common causes

Answer 9

o Anemia = most common cause
 ↓ blood viscosity tend to occur when Ht < 22-25%
o Hypertension
o Fever
o Pregnancy
o HyperT4

Question 10

Regurgitant murmurs charateristics

Answer 10

• Longer duration (vs ejection murmurs): start with S1, end at or include S2
• Plateau configuration
• High frequencies with high pitched/blowing quality

Question 11

Features of MR murmur

Answer 11

o Holosystolic, plateau shaped
 Frequent late systolic attenuation
o Soft: protosystolic
o Mixed frequency and harsh sounding
* Loudest at L cardiac apex
o Radiates dorsally and to R thorax
 If chordae tendineae rupture: radiation can vary according to which chordae
* Posterior: base of heart + 50% to neck and carotids
* Anterior: axilla and mid thoracic vertebrae, top of head
o Confounding reliable identification of TR)
* Common accentuation of P2

Question 12

Regulation of blood flow across MV depend on

Answer 12

malfunction of any component can lead to MR
o MV annulus
o MV leaflets
o Chordae tendineae, papillary muscles

Question 13

Causes of MR murmur

Answer 13

o CVD: clicks may be present if valve prolapse
 Loudness of murmur α severity
o DCM: annular dilation → mild to moderate loudness
 Arrhythmias often present
o Systemic hypertension

Question 15

Causes of TR murmur

Answer 15

o PH: primary or secondary
o TVD

Question 16

Type of HM: SAS

Answer 16

systolic crescendo-decrescendo murmur
o L heart base or R cranial thorax
o Intensity α severity
 Mild obstruction: mild murmur that ↑ w exercise (↑ SV)
 Moderate to severe: harsh murmur, mixed frequency, long
* Can radiate to thoracic inlet up to neck, along carotid arteries

Question 17

Type of HM: PS

Answer 17

• Murmur: harsh, med to high pitched, loud & long systolic
  o Loudest at L base, over PV
  o Opening snap: fused valve leaflet reach opening limit
  o Wide S2 split

Question 18

Type of HM: HOCM

Answer 18

• Similar to SAS
• Can have concomitant MR
  o Secondary to MV leaflet displacement w SAM
  o Papillary muscle dysfct or distortion of MV annulus

Question 19

Type of HM: VSD

Answer 19

• Restrictive physiology of VSD
  o Determined by amount/velocity of shunt from L to R
   Size of VSD (larger = ↓ velocity of shunting)
   Pulmonary vascular resistance (PH = ↓ shunting)
• Loud, harsh murmur
  o Holosystolic, medium to high pitched
   If PH, may be protosystolic
  o Plateau or mild crescendo-decrescendo
  o L cranial thorax
• Can have soft ejection systolic murmur: functional/relative pulmonic stenosis 2nd to ↑ flow

Question 20

Type of HM: ASD

Answer 20

• Systolic ejection murmur: medium pitched, short, soft
  o Loudest over PV area
  o Crescendo-decrescendo
  o Splitting of S2 → fixed respiratory splitting
• Increased blood flow across PV → delayed closure

Question 21

Type of HM: TOF

Answer 21

• VSD: R sternal border murmur
• PS: L basilar ejection murmur
  o Tend to predominate
• Nature/intensity of murmur → reflect
  o Severity of Ao override → degree of PS/hypoplasia
   More severe PS → ↑ RV pressure → ↑ R to L shunting → soft murmur
  o Degree of R to L shunting

Question 22

Mechanism of diastolic murmurs

Answer 22

• 2 major mechanisms
  o Regurgitant flow across incompetent Aov or PV
  o Forward flow across stenosed MV or TV

Question 23

Type of HM: MS

Answer 23

• Murmur: low pitched, low frequency, rumbling
  o Starts mid diastole after S2
• In Hu: duration α to severity
• Triscuspid stenosis: similar, best heart over Tv area, extremely rare

Question 24

Type of HM: AI

Answer 24

• Most common diastolic murmur
  o Aortic endocarditis in adult dogs
  o Young dogs:
   Isolated congenital defects
   SAS
   Complication of VSD
• Murmur: soft, blowing, high pitched
  o Crescendo-decrescendo
  o Start immediately after S2
  o Split S2 may be present
• Disparity btwn loudness of murmur and degree of AI
  o Severe AI = soft, short
  o Moderate AI = no audible murmur

Question 25

Austin Flint murmur

Answer 25

Severe AI: presystolic murmur (Austin Flint) o 2nd to premature MV closure → disturbed diastolic flow through M

Question 26

Type of HM: PI

Answer 26

* Uncommon to have PI of sufficient magnitude to cause murmur o If 2nd to PH: usually louder, harsher, longer duration * Murmur: soft, high pitched, blowing o Early in diastole o Decrescendo o Best heard in PV area o Usually with an ejection systolic murmur

Question 27

Continuous murmur: cause

Answer 27

abnormal flow from arterial to venous circulation * Characteristic murmur of PDA o Blood flows from Ao (↑ pressure) to PA (↓ pressure) → turbulence  Loudness/duration = pressure gradient btw Ao and PA  If PH: ↓ intensity of diastolic component, ↑ S2 intensity * Reversed shunt: no murmur o Other differentials:  Pulmonary arteriovenous fistula (AP window)  Arteriovenous fistula  Ruptured sinus aneurysm or CA communicate w RA  Severe aortic coarctation  PA branch stenosis  Anomalous origin of LCA from PA  Accessory CA  Coronary stenosis  Truncus/pseudotruncus arteriosus  Total anomalous pulmonary venous connection

Question 28

Features of continuous HM

Answer 28

* Continuous systolic and diastolic murmur o Best heard over AoV and PV o Start with S1, max intensity before S2, decrescendo toward next S1 o Waxes and wanes → peak intensity = around S2 o Systolic component often radiate extensively, diastolic localized  Diastolic can be lost at end diastole * Systolic regurgitant murmur can be heard at L apex

Question 29

Features of To and Fro HM

Answer 29

* Systolic + diastolic murmur * Often combination of congenital defects

Question 30

Causes of To and Fro

Answer 30

* SAS + AI * VSD + AI * PS + PI * Mitral atresia + ASD (Lutembacher syndrome)

Question 31

Horses w/ AI also have

Answer 31

holodiastolic w decrescendo character o Can ↑ intensity at end diastole w atrial contraction → opening of MV → anterior septal leaflet hit regurgitant flow  Austin Flint murmur

Question 32

DDX ejection systolic click

Answer 32

 Early in systole o Hypertension o Dilation of great vessel o Opening of abnormal but mobile semi lunar valve  Causes: o Systemic hypertension o PA dilation: idiopathic, PH o Tetralogy of Fallot o AS/PS o HW dz

Question 33

DDX non ejection systolic click

Answer 33

 Short, mid to high frequency sound  Mid to late systole  Causes: o AV prolapse o CVD

Question 34

DDX protodiastolic transient sounds

Answer 34

 Opening snaps o Tricuspid or mitral stenosis  Tumor o Atrial tumor/myxoma  Pericardial knock o Constrictive pericarditis w abrupt termination of rapid ventricular filling  S3 protodiastolic gallop o LV or RV diastolic overload o AI, PI, MR, TR o L → R shunt o High output states (anemia, hyperT4) o ↓ ventricular compliance or ↑ diastolic pressures o CM o Ventricular failure o Ischemic heart dz

Question 35

What feature during physical examination can separate tricuspid from mitral valve regurgitation?

Answer 35

Timing of murmur associated with respiration * TR: ↑ murmur intensity with inspiration o Carvallo’s sign o Inspiration: ↓ intrathoracic pressure → ↑ venous return to R heart → ↑ regurgitant flow across the TV * MR: murmur intensity is not affected by respiratory cycle

Question 36

Dynamic auscultation

Answer 36

 Clinical assessment → alter venous return or SV o Rapid squat: blood volume stored in legs forced to return to heart  ↑ venous return → ↑ preload → ↑ LV filling

Question 37

Effect of dynamic auscultation on HOCM

Answer 37

↓ intensity * ↑LV volume → displace hypertrophied IVS → ↓ LVOTO

Question 38

Effect of dynamic auscultation on MR

Answer 38

later systolic click

Question 39

Dynamic auscultation: hand grip

Answer 39

↑BP → ↑ afterload  ↑MR, AI intensity  No effect on AS

Question 40

Dynamic auscultation: amyl nitrate

Answer 40

↓LV afterload  ↓MR: ↓ resistance to blood flow → ↑SV and ↓ regurgitant volume

Question 41

Valsalva maneuver

Answer 41

squat to stand => vasodilation

Question 42

Effect of Valsalva maneuver on MR

Answer 42

↑ forward flow → shorter + softer

Question 43

Effect of Valsalva maneuver on SAS

Answer 43

↑ intensity

Question 44

Effect of Valsalva maneuver on HOCM

Answer 44

↓ intensity  ↑LV volume → displace hypertrophied IVS → ↓ LVOTO

Question 45

Effect of Valsalva maneuver on AI

Answer 45

↑ forward flow → ↓ murmur

Question 46

Inspiration/hand grip: effect on MR

Answer 46

Inspiration/hand grip: effect on MR