Making a diagnosis Flashcards
Causes of systolic murmurs in horses
Physiological flow murmurs
Mitral insufficiency
Tricuspid insufficiency
Ventricular septal defects
Location of physiological flow murmurs
Loudest cranially on left, LIC4
Timing/intesnsity of physiological flow murmurs
Early to mid systolic
Tend to be low grade
Importance of physiological flow murmurs
None
Important DD for MR
Radiation of physiological flow murmurs
Cranio-dorsal
Mitral insufficiency in horses
Common, second commonest form of VHD
Most common cause of clinical signs of cardiac disease
Murmur of mitral insufficiency
Grade: 1-6
Timing: early, mid, holo, pan-systolic
Shape: band shaped
Loudest: left 5th intercostal space
Radiates: caudodorsally
Signalment for mitral insufficiency
All age groups
Clinical signs of mitral insufficiency in horses
Incidental findings
Poor Performance
Atrial fibrillation
Left-sided failure (Acute onset)
Right-sided failure
Collapse, fainting or sudden death
Mitral insufficiency disease progression
Diastole:
- increased ventricular filling
- loud third heart sound
Systole
- increased ventricular work will increase the regurgitant fraction
- Left atrial enlargement > AF
Can have a very loud 3rd sound as increased ventricular filling
Blood will leak back into lungs leading to pulmonary artery being at point of failure
Right sided heart failure
Prognostic indicators in mitral insufficiency
Loud murmus (grade 3 and above)
Loud 3rd heart sound
Dysrrhythmia (atrial fibrillation)
Congestive heart failure (left or biventricular)
Bacterial endocarditis
Pulmonary hypertension
Left atrial enlargement
Tricuspid insufficiency in horses
May be related to hypertrophy (training)
Generally well tolerated in TB
Less common in other breeds
§ Bacterial endocarditis - secondary to septic jugular thrombosis
§ Dental disease
§ Other causes?
Negative prognostic indicators of tricuspid insufficiency
Loud murmurs (4 and above in TB)
Loud third heart sound
Dysrrhythmia (atrial fibrillation)
Congestive heart failure (right sided)
Bacterial endocarditis
Pulmonary hypertension
Right atrial enlargement
Ventricular septal defects in horses
Common in welsh ponies
Size of defect determines significance - if small can be athletes
Murmur intensity is not a useful guide to severity
Concurrent systolic murmur on LHS (LIC 4)
§ Relative pulmonic stenosis
Often quieter in summer as pony puts on weight
Negative prognostic signs for VSD
Murmur grade not useful
Secondary diastolic murmur
Defect size
Cardiac enlargement
Usually left sided
Causes of diastolic murmurs in horses
Ventricular filling murmurs
Aortic insufficiency
Pulmonic insufficiency
Continuous cardiac murmurs
Location of ventricular filling murmurs
Loudest behind triceps
LIC5 - often towards apex (Sternum)
Timing/intensity of ventricular filling murmurs
Mid diastolic murmurs
Importance of ventricular filling murmurs
Physiological
Variable
Aortic insufficiency in horses
Commonest form of equine VHD
Middle-aged or older horses
Frequently an incidental finding
Progressive condition clinical signs in older horses
Murmur of aortic insufficiency
Grade: 1-6/6
Timing: Early or holo DIASTOLIC
Shape: Decrescendo
Loudest: Left 4th intercostal space
Clinical examination of a horse with aortic insufficiency
Bounding (hyperkinetic) pulses
May have concurrent mitral insufficiency
Ventricular arrhythmias in a horse with aortic insufficiency
Higher prevalence of ventricular arrhythmias in horses with aortic insufficiency compared with other forms of valvular insufficiency
Incidental finding
Concurrent myocardial and endocardial pathology
Catecholamine-induced?
Altered coronary artery blood flow?
Echocardiography of a horse with aortic insufficiency
Left ventricular enlargement
Mitral valve regurgitation
Jet size
Negative prognostic signs for horses with aortic insufficiency
Murmur grade is not useful indicator
Secondary MR
Pulse pressure is associated with severity
Congestive heart failure
Left or biventricular
Bacterial endocarditis
Left ventricular enlargement
Defect size and valvular lesions
NIBP pulse pressure >60mmHg
EXERCISING ELECTROCARDIOGRAPHY
Pulmonic insufficiency in horses
PI is uncommon in the horse
When it occurs it rarely affects performance
A common echocardiographic finding
Cor pulmonale
Right ventricular hypertrophy
§ Pulmonary Hypertensin
§ Alveolar hypoxia
□ Marked respiratory distress
□ PA enlargement and PI
Continuous cardiac murmurs
Aortic root rupture
Aorto-cardiac fistula
Continuous loud cardiac murmur
§ Grade 4-6/6
§ Often accompanied by ventricular tachycardia (>100bpm)
□ Disruption to interventricular
conduction tissue
§ Usually fatal
□ Acute cardiac failure
□ Collapse
□ Exsanguination
Fresians in scandinavia
Valvular pathology in horses
Bacterial endocarditis
○ New cardiac murmurs associated with severe disease
○ Clinical signs:
§ Acute onset Congestive heart failure
§ Fever, cardiac murmur, tachycardia, tachypnoea
○ Laboratory data
§ Hyperfibrinogenaemia, anaemia and leucocytosis
§ Blood culture
□ Repeat x3 (false negatives) ideally
□ when pyrexic
□ Sterile procedure (do not use indwelling catheter)
Colic and heart murmurs in horses
New cardiac murmurs may be heard in horses with colic
○ Flow murmur
○ Regurgitant
○ Quite loud
Occasionally cardiac dysrhythmias also may be identified
○ GI disease
○ Electrolyte imbalances
Horses in acute left sided heart failure show signs similar to colic
