Equine Dysrhythmias

These flashcards cover key concepts and details regarding equine dysrhythmias, including diagnosis, treatment, and common conditions related to cardiac health in horses.

What are the learning outcomes of the lecture on Equine Dysrhythmias?

To evaluate myocardial damage, record and interpret electrocardiographic abnormalities, understand common dysrhythmias, and diagnose/treat atrial fibrillation.

What is the significance of myocardial disease in horses?

It causes abnormalities in contraction and can manifest as cardiac dysrhythmias or even collapse/sudden death.

What are some clinical signs that myocardial disease may manifest?

No clinical signs, poor performance, atrial fibrillation, collapse, ventricular premature beats, and ventricular tachycardia.

What is the role of an ECG in diagnosing cardiac dysrhythmias?

It helps in diagnosing and evaluating the underlying cause of the dysrhythmia.

What are some conditions that could lead to myocardial dysfunction in horses?

Electrolyte abnormalities, increased myocardial muscle mass, increased chamber size, cardiomyopathy, and myocarditis.

What are the types of proteins evaluated in myocardial disease assessment?

Cardiac troponin I and creatine kinase (myocardial isoenzyme).

What is myocarditis?

Inflammation of the myocardium that can be bacterial, viral, or parasitic.

What is dilated cardiomyopathy (DCM) in horses?

The only significant type of cardiomyopathy reported, characterized by dilated ventricles.

What advanced techniques are used for myocardial evaluation?

Echocardiography, stress echocardiography, and myocardial biopsies.

What is the purpose of telemetric/Holter systems in equine cardiology?

They provide 24-hour continuous monitoring of ECGs and can record during exercise.

What is considered the most important cardiac dysrhythmia in horses?

Atrial fibrillation (AF).

What triggers atrial fibrillation in horses?

Electrolyte/acid-base imbalances, anesthetic and drug administration.

What are the clinical signs associated with atrial fibrillation?

Exercise intolerance, poor performance, epistaxis, weakness, and possible collapse.

How is atrial fibrillation diagnosed?

Through auscultation, physical examination, resting ECG, and further diagnostics for underlying causes.

What are the key treatment options for atrial fibrillation?

Quinidine sulfate, DC cardioversion, and continuous ECG monitoring.

What is the prognosis for paroxysmal atrial fibrillation without recurrence?

Excellent to good.

What is the main cause of ventricular dysrhythmias in horses?

Electrolyte imbalances, myocardial diseases, or drug effects.

What are the criteria for pharmacologic management of acute tachyarrhythmias?

Symptoms of poor cardiac function, laboratory parameters indicating poor perfusion, or presence of malignant arrhythmias.

How is lidocaine used in the treatment of ventricular tachycardia?

As a first-line drug, administered IV with a specific dosage schedule.

What adverse effects are associated with lidocaine?

CNS toxicities including muscle twitching, disorientation, and risk of arrhythmias.

What does magnesium do in the context of dysrhythmias?

It can be effective for refractory ventricular dysrhythmias and works as a cofactor in the Na/K ATPase system.

How does AF affect exercise in horses?

It does not affect cardiac output at rest but significantly reduces it during exercise.

What are common outcomes of untreated sustained atrial fibrillation?

Poor to grave prognosis, especially in the presence of heart failure.

What is a distinguishing feature of AF during physical examination?

Irregularly irregular rhythm.

What characterizes 'paroxysmal' atrial fibrillation?

Episodes that last less than 24-48 hours and may spontaneously convert.

What are the potential side effects of quinidine used in atrial fibrillation treatment?

Fatal dysrhythmias, colitis, and irritant effects on mucosa.

What types of dysrhythmias are considered incompatible with life?

Asystole and ventricular fibrillation.

What treatment is appropriate for managing drug-induced bradyarrhythmias?

Anticholinergics like atropine and glycopyrrolate.

What case presentation describes a 12-year-old TB horse with a heart murmur?

Pulled up lethargic, has a grade IV/VI holosystolic murmur and irregular rhythm.

What treatment options are available for ventricular dysrhythmias?

Lidocaine, magnesium, procainamide, and amiodarone.

What is the importance of assessing electrolytes before treating atrial fibrillation?

To identify and correct imbalances that may worsen the condition.

What is 'Ventricular Pacing'?

A treatment option for bradyarrhythmias in horses requiring medical management.

What are common side effects to monitor for during AF treatment?

Toxicity indicated by QRS complex prolongation and other cardiovascular effects.

Who authored the Equine Dysrhythmias lecture?

Dr. Adam Redpath.

What should be considered when performing a physical examination for AF diagnosis?

HR and pulse quality may vary, and normal or decreased HR is common.

What necessitates further investigations in cases of advanced second degree AV block?

Persistence at exercise or abnormal clinical signs.