Endocardial Disease in Large Animals: Cardiac Murmurs Flashcards
What are the 3 categories of heart murmurs in the large animal and give examples of each?
Not associated with valve pathology
+ physiological murmurs in the horse, functional valve regurg
Associated with valve pathology
+ Endocarditis, valve degeneration/prolapse, ruptured chordae tendinaeae
Congenital abnormailites
+ VSD, PDA, valvular dysplasia
Following cardiac auscultation, how might you further evaluate a cardiac murmur?
Echocardiography
+ Confirmation of diagnosis
+ Assess severity
+ Determine prognosis
Electrocardiography
+ Little value in murmurs assessment
+ But may identify concurrent arrhythmias
What types of echocardiography can be used?
2D and M mode
Doppler
What can 2D and M-mode echo be used to assess?
Valve structure and function
Chamber size
Myocardium
Describe 2D echocardiography imaging
Allows structures to be viewed moving in real time in a cross-section of the heart
Detects abnormal anatomy or movement of the structures
Describe M-mode echocardiaography imaging.
Provides a 1D view
Used for fine measurements
Temporal and spatial resolutions are higher because the focus is on only one of the lines from the 2D trace
Describe doppler imaging..
Estimates of blood-flow velocity made by comparing the frequency change between the transmitted and reflected sound waves
Continuous wave, pulsed wave or colour flow mapping
What type of blood flow produces a murmur?
Turbulent
Describe aortic flow murmurs in horses…
Physiological murmur
Early-mid systolic crescendo to decrescendo
Common
Quiet (< Grade III)
PMI aortic valve or heart base
Effect of exercise variable, but generally disappears as the turbulent flow becomes laminar
Normal, especially in fit horses
What is the diameter of the aorta in a thoroughbred?
10-12cm
Describe ventricular flow murmurs in the horse…
Physiological murmur Early diastolic Mitral and tricuspid waves Less common than aortic flow Short duration High pitched 'squeak' After S2 but before S3 PMI heart base or AV values Normal, especially in young TBs but usually disappears with age
Which valve does valve regurgitation most commonly occur in in the horse?
Mitral > Tricuspid > Aortic
Is valve regurgitation significant in the horse?
Many are non-progressive “functional regurgitations”
Or may be associated with valve pathology (significance is related to cause, they may be progressive or have a sudden onset and can be fatal)
How can you differentiate between a pathological and function valve regurgitation?
Echo
Why does valve regurgitation occur in the healthy horse?
Physiological phenomenon in fit and healthy animals.
Valves can’t quite close as the heart gets bigger, so there is a small amount of regurgitation
What % of horses in training have valve regurgitation?
30%
Describe mitral regurgitation in the horse…
Systolic murmur
Significance and auscultation findings vary with cause (quiet may be functional murmur)
Differentiate by observing progression over time
Intensity and radiation increases with severity
PMI left 5 rib
How can mitral regurgitation lead to collapse and death in the horse
Flow from the left ventricle to the left atria leads to high pressures in the left atria. The pressure builds up in the pulmonary veins, circulation and artery. These can rupture as a consequence of forward and backward pressure.
At what intensity can 3+ murmurs be heard at the opposite chest wall of a horse?
At the volume of a murmur 2 grades lower (radiates across)
Describe tricuspid regurgitation in the horse..
Significance and auscultation findings vary with the cause (may be a quiet “functional” murmur
Intensity and radiation increase with severity
Intensity is between 1 and 6 out of 6
Can be heard early, mid, holo or pan systolic
Have a plateau shape
PMI right 4th intercostal space (apex)
Radiates craniodorsally
When might mitral regurgitation be significant in the horse?
When associated with poor performance Resting tachycardia Abnormal pulse, slow CRT Signs of LSHF Arrhythmias, particularly AF Louder than grade 4 Wide radiation
What is aortic regurgitation often due to in the horse?
Endocardiosis
Describe aortic regurgitation in the horse…
Common in older horses
Incidental finding
Often slowly progressive
Intensity between 1 and 6
Holodiastolic between S2 and S4
Decrescendo sound
PMI is aortic valve
When might tricuspid regurgitation be significant in the horse?
Associated with poor performance Resting tachycardia Abnormal pulse Signs of right sided failure Arrhythmias, especially atrial fibrillation Louder than grade 4 Wide radiation
What are the top 3 causes of poor performance in horses?
Lameness
Respiratory
CVS
When may aortic regurgitation be significant?
Associated with poor performance
Resting tachycardia
Bounding “hyperkinetic” arterial pulse
+ due to large systolic/diastolic pressure difference (regurgitation into the left ventricle)
Slow CRT
Signs of left sided heart failure
Arrhythmias, especially atrial fibrillation
What are the common causes of murmurs associated with valve pathology in large animals?
Degenerative valve disease
Bacterial endocarditis
What are the chorda tendonae attached to?
Papillary muscles
What does bacterial endocarditis occur secondary to?
Bacteraemia
What are the usual primary sites of bacteraemia in bacterial endocarditis of cattle?
Liver abscess Traumatic reticulitis Metritis Mastitis Navel abscess "Joint ill"
How would you diagnose bacterial endocarditis?
Clinical signs:
Congestive heart failure
Fever, cardiac murmur, tachycardia, tachypnoea
Clinical pathology:
Hyperfibrinogenaemia, anaemia and leucocytosis
Blood culture
What areas of the heart are usually affected by bacterial endocarditis in:
a. Ruminants
b. Horses
c. Pigs
a. Tricuspid and pulmonic valves. Right ventricular endocaridum.
b. Mitral >aortic. Can include aortic root. Right sided associated with jugular thrombophlebitis
c. Mitral, aortic
What is the prognosis for animals affected by bacterial endocarditis?
Guarded even following bacterial cure as permanent structural damage to valve. In horses some RHS lesions may have retruned performance
Septic emboli may shed to distant sites e.g. lung, kidneys and joints
What do you need to diagnose valvular prolapse?
Echo
What are ruptured chordae tendinae a common cause of?
Horses collapsing and dying at exercise
What can ruptured chordae tendinae arise as a result of?
Spontanteously or secondary to inflammatory or degenerative changes
What congenital abnormalities can lead to murmurs?
VSD
PDA
Valve dysplasia
Describe VSD in large animals..
Most common congenital cardiac defect in large animals
In almost all VSDs the defect is in dorsal (membranous) part of the septum, but may be a patent ductus arteriosis
2 murmurs producing a “diagonal” murmur
RHS murmur is associated with the LV to RV shunt
LHS murmur is associated with RV overload, “functional” pulmonic stenosis
Intensity is inversely proportional to the size of the defect (loud does not always indicate severe, large VSDs produce less turbulence so are quieter)
When does the ductus arteriosus normally remain patent till in the foal?
7-10 days
Describe RHS and LHS VSD murmurs in large animals…
RHS Holo-pansystolic Coarse Plateau Grade 3-6 PMI tricuspid valve Wide radiation
LHS Holo-pansystolic Crescendo-decrescendo Grade 3-6 Wide radiation
Describe patent ductus arteriosus
Blood flows along PSA in both systole and diastole producing a washing machine murmur
Grade 3-5, with wide radiation
PMI is at the LH base and radiates to RHS
What is the cause of aortic murmurs?
The diameter of the aorta is large so can get non-laminar flow at rest
What are the causative agents of bacterial endocarditis in:
a. ruminants
b. horses
c. pigs
a. Enterococci, Streptococci, Actinomyces pyogenes
b. Pasteurella, Acintobaccillus, Streptococci, Rhodococcus equi
c. Staph aureus, Actinobacillus suis, Erysipelothrix rhysiopathiae
