Cardiovascular

Question 1

What is a “dropped beat”? How can it be resolved?

Answer 1

•The failure of one of the ventricles to contract because the signal does not transmit from the atria
•resolves with exercise, occurs in 44% of horses

Question 2

What is a physiologic murmur?

Answer 2

A heart murmur that is not caused by pathology and resolves with exercise.

Question 3

What is echocardiography?

Answer 3

•An ultrasound of the heart
•Evaluates size and wall thickness of the heart, valve function and structure, blood vessel structure, and blood flow

Question 4

What is electrocardiography?

Answer 4

•measurement of the electrical activity of the heart
•can help define variance in heart rhythm, cannot determine heart size

Question 5

What is exercise and stress testing? What is the Ridgeway test?

Answer 5

•A test to evaluate oxygen levels in the blood during exercise
•Measuring a horse’s resting heart rate. Then having the horse jog away for 125 feet, and remeasuring. Remeasure a third time exactly 60 seconds after the previous measurement.

Question 6

What is Atrial Fibrillation? How common is Atrial Fibrillation in horses?

Answer 6

•When the atrium vibrates instead of pumping normally, making it impossible to empty effectively and continue blood circulation. This disrupts the normal pattern of electrical signals that stimulate heart rhythm, and causing the ventricles to contract randomly and independently.
•It is the most common cardiac rhythm disruption in horses
•May be a secondary symptom, or a primary condition

Question 7

How is Atrial Fibrillation diagnosed?

Answer 7

○Clinical Signs
•Poor performance
•Shortness of breath
•Easily exhausted
•Coughing
•Nasal discharge
•Sudden deceleration during a race
•Sometimes no clinical signs
○No detectable heart rhythm on auscultation
○Absent fourth heart sound
○Electrocardiogram
○Ultrasound (if there are comorbid symptoms suggesting further heart disease)

Question 8

How is Atrial Fibrillation treated?

Answer 8

If there are no other signs:
•Anti-arrhythmic drugs- quinadine (has serious side effects including inappetence, depression, swollen nasal mucosa, ataxia, diarrhea, and colic)

If Atrial Fibrillation is accompanying an underlying disease:
•Primary disease should be treated first

Question 9

How serious is Atrial Fibrillation? What complications can occur?

Answer 9

•Severity is determined by duration and presence of underlying disease
•Many athlete horses have Atrial Fibrillation
•Prognosis varies depending on comorbidities