Arrhythmias in LA/Horses Flashcards

1
Q

What can cause arrhythmias in LAs?

A

Primary (infectious, nutritional, others e.g. cardiomyopathy, neoplasia, or idiopathic) or Secondary (endotoxaemia, hypoxia, electrolyte or acid-base disturbances)

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2
Q

Would you use an Echo or ECG to tell you about arrhythmias in horses?

A

ECG used to tell you about cardiac rate and rhythm.

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3
Q

What is second degree AV block?

A

When the AV node only conducts some of the depolarisations from the atria (i.e. not a QRS for every P)

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4
Q

Why is it normal for horses to have second degree AV block?

A

They have high vagal tone.

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5
Q

What would you hear/see on an ECG with second degree AV block in horses?

A

Regularily irregular blocking of the P wave, isolated fourth heart sound wound be heard before block. Usually slow heart rate.

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6
Q

What is atrial fibrillation? What would you see on an ECG?

A

AF is the commonest pathological arrhythmia in horses. It is caused by no coordinated contraction of the atria, so there is fibrillation. No P waves, but there are fibrillation waves.

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7
Q

What would you hear/see on an ECG with atrial fibrillation in horses?

A

Irregularily irregular heartbeat with no 4th heart sound. No P waves, only F waves. Usually normal rate.

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8
Q

What clinical signs would you expect with atrial fibrillation?

A

Often there may be none in horses not very physically activity, may be incidental. May see excercise intolerance in those with a higher work load.

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9
Q

How can you differentiate 2nd degree AV block from AF?

A

AF is irregularily irregular with no 4th heart sound, no P waves. 2nd degree AV block is regularily irregular with a 4th heart sound, and P waves on ECG. 2nd degree also has slow HR, AF usually normal.

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10
Q

If the owner wants to treat AF, how can it be done in horses? Why is this decision not taken lightly? (Would not usually treat happy hackers)

A

Quinidine sulphate, considered due to side effects (ventricular tachycardia, hypotension, decreased CO, diarrhoea, can be fatal.

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11
Q

Is it safe to ride a horse with AF?

A

Some horses with AF may get VPC’s, leading to VF and death. Therefore you ALWAYS do an excercising ECG looking for ventricular abnormalities before saying safe to ride.

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12
Q

What makes a horse with AF a good candidate for treatment with Quinidine sulphate?

A

No underlying heart disease, going on for less than 4 months, normal heart rate.

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13
Q

What is an Atrial premature complex? How would it look on an ECG?

A

When atria prematurely contract. It may or may not be conducted by the AVN. It is an abnormal P followed by a normal QRS if conducted, or no QRS if non-conducted.

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14
Q

What is an Ventricular premature complex? How would it look on an ECG? Are the significant?

A

When the ventricle contracts by itself. It is an abnormal wide and bizarre QRS, with no preceding P wave. Much more likely to progress onto VF and death than APC.

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15
Q

What is Ventricular tachycardia?

A

When heartbeat starts in ventricle, 3 or more VPC’s. It can me uniform or multiform based on how many different types of VPC’s.

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16
Q

What is supraventricular tachycardia? What do they normally look like on an ECG?

A

Rapid heard rhythm originating at or above the AVN. Usually have narrow upright complex.