Veterinary Cardiology Quiz

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Questions and Answers

What is the most likely cause of a ventricular premature complex (VPC) in a dog?

Drug administration

Electrolyte derangements

Heart disease (correct)

Pain

What is the rate of a ventricular tachycardia in a dog?

Greater than 250 beats per minute

Less than 160 beats per minute

Greater than 160 beats per minute (correct)

Less than 40 beats per minute

What characteristic of a VPC on an ECG is considered "wide and bizarre"?

The QRS complex (correct)

The ST segment

The P wave

The T wave

What is the most dangerous arrhythmia mentioned in the text?

Ventricular fibrillation (C) Signup and view all the answers

What condition is a potential complication of sustained ventricular tachycardia?

Congestive heart failure (B) Signup and view all the answers

What is the most appropriate treatment for a dog with single VPCs without signs of hemodynamic compromise?

Long-term ECG monitoring (B) Signup and view all the answers

R-on-T phenomenon is associated with an increased risk for?

Ventricular fibrillation (B) Signup and view all the answers

What is a common characteristic of a R-on-T phenomenon on an ECG?

A very fast heart rate (B) Signup and view all the answers

What characterizes a ventricular arrhythmia concerning the QRS complex?

Wide and bizarre (B) Signup and view all the answers

In dogs, what heart rate indicates tachycardia?

<blockquote> 160 bpm (C) </blockquote> Signup and view all the answers

What can cause a fast heart rate associated with sinus rhythm in dogs?

Fear and excitement (A) Signup and view all the answers

What is a notable characteristic of respiratory sinus arrhythmia in dogs?

Regularly irregular rhythm associated with respiration (D) Signup and view all the answers

What does a wide QRS complex indicate in the context of an ECG?

Ventricular origin of impulses (C) Signup and view all the answers

In which scenario is no treatment typically necessary?

Increased vagal tone in dogs (D) Signup and view all the answers

What is a common cause of ectopic supraventricular tachyarrhythmia?

Severe mitral valve disease (C) Signup and view all the answers

Which of the following would NOT be a likely cause of sinus tachycardia?

Vagal stimulation (A) Signup and view all the answers

What is the expected QRS duration that indicates a wide QRS complex in dogs?

Greater than 0.06 sec (D) Signup and view all the answers

What condition could lead to a transient increase in heart rate in dogs?

Pain or fear (B) Signup and view all the answers

What is the heart rate calculation method when counting QRS complexes in a 3-second period?

Count QRS complexes and multiply by 20 (A) Signup and view all the answers

Which paper speed setting corresponds to each small (mm) box measuring 0.02 seconds?

50 mm/sec (D) Signup and view all the answers

What is the correct method for calculating average heart rate using a standard Bic pen at 25 mm/sec?

Count QRS complexes inside the pen length and multiply by 10 (C) Signup and view all the answers

Which component of the ECG system allows you to determine whether the rhythm is controlled by the sinus node?

Lead II electrocardiogram (B) Signup and view all the answers

In the systematic approach to ECG interpretation, what is the first step?

Note lead and paper speed settings (A) Signup and view all the answers

What does the QRS complex appearance help differentiate between?

Supraventricular and ventricular arrhythmias (C) Signup and view all the answers

How long is a standard Bic pen when it is used for measuring heart rate at 50 mm/sec?

150 mm (A) Signup and view all the answers

What is the normal sinus rhythm characterized by?

Regular intervals and a consistent rate (D) Signup and view all the answers

What defines an underlying sinus rhythm in an electrocardiogram (ECG)?

Presence of P waves for QRS complexes and consistent PR intervals. (A) Signup and view all the answers

What is a common consequence of tachycardia on cardiac output?

Decreased stroke volume due to inadequate filling time. (C) Signup and view all the answers

Which heart rhythm is specifically known to cause loss of atrio-ventricular synchrony?

Atrial fibrillation. (C) Signup and view all the answers

What characterizes a ventricular arrhythmia?

QRS complexes appear wide and bizarre. (D) Signup and view all the answers

Which of the following statements about bradyarrhythmias is correct?

They can lead to cardiac injury due to decreased cardiac output. (A) Signup and view all the answers

What is the primary hemodynamic consequence of atrial fibrillation at high heart rates?

Loss of atrial kick leading to decreased exercise tolerance (B) Signup and view all the answers

Which condition is described as the inability of the heart to maintain adequate output during physical exertion?

Sinus bradycardia. (A) Signup and view all the answers

Which characteristic on an ECG is indicative of atrial fibrillation?

Irregular, sawtooth baseline caused by fibrillation (f) waves (B) Signup and view all the answers

In which scenario is 'lone A-fib' most likely to occur?

In giant-breed dogs without underlying heart disease (A) Signup and view all the answers

How is a supraventricular arrhythmia differentiated from a ventricular arrhythmia?

Supraventricular arrhythmias have a normal QRS complex. (C) Signup and view all the answers

What feature is indicative of an abnormal impulse arising from the ventricular region?

QRS complexes longer than 0.06 seconds in dogs. (D) Signup and view all the answers

What does the AV node do in response to rapid atrial activity during atrial fibrillation?

It acts as a filter for the rapid atrial impulses. (B) Signup and view all the answers

Which category includes both sinus bradycardia and atrial fibrillation?

Cardiac arrhythmias. (C) Signup and view all the answers

What is the typical heart rate associated with atrial fibrillation in dogs?

Usually above 180 bpm (A) Signup and view all the answers

Why is it essential to identify the origin of a heart rhythm?

To assess the potential impact on cardiac output. (C) Signup and view all the answers

What is an early sign of 'lone A-fib' in giant-breed dogs?

Severe exercise intolerance or decreased performance (C) Signup and view all the answers

What is the most common approach to manage abnormal ventricular response rates in dogs and cats?

Rate control using oral antiarrhythmics (C) Signup and view all the answers

What is the expected QRS complex appearance in atrial fibrillation?

Narrow and upright complexes (A) Signup and view all the answers

Which treatment is aimed at converting atrial fibrillation to sinus rhythm?

Rhythm control measures (C) Signup and view all the answers

Which characteristic is NOT associated with premature ventricular complexes (PVCs)?

Presence of a related P wave (A) Signup and view all the answers

How can one identify if the premature beats have a ventricular origin?

By the width of the QRS complex (A) Signup and view all the answers

What does the term 'R-on-T' phenomenon refer to in ECG readings?

QRS complex occurs on the T wave of a previous beat (D) Signup and view all the answers

Which of the following is a feature of ventricular premature depolarizations?

Can appear as single, couplets, or triplets (A) Signup and view all the answers

What is indicated by a QRS complex width greater than 0.06 seconds in a dog?

Possible ventricular origin of a beat (B) Signup and view all the answers

Which type of medication is commonly used to control heart rate in dogs with arrhythmias?

Beta-adrenergic blockers (A) Signup and view all the answers

What are the building blocks for more complex ventricular arrhythmias such as ventricular tachycardia?

Ventricular premature complexes (D) Signup and view all the answers

Study Notes

ECG Interpretation

A systematic approach to ECG interpretation involves several steps
First, note the lead and paper speed settings, typically 25 mm/sec or 50 mm/sec.
Determine the heart rate by counting QRS complexes in a 3-second period and multiplying by 20.
Establish if there is an underlying sinus rhythm.
Describe any rhythm abnormalities if absent.

Learning Objectives

Students will list and discuss the steps in ECG interpretation.
Students will identify the presence of a sinus rhythm.
Students will define cardiac arrhythmias and normal sinus rhythm.
Students will list the criteria of a normal sinus rhythm using ECG leads.
Students will identify rhythms controlled by the sinus node in ECG leads.
Students will differentiate between supraventricular and ventricular rhythms (ECG criteria)

Bic Pen Trick

A standard Bic pen can be used to quickly estimate heart rate.
Count the QRS complexes contained within the length of the pen.
Multiply the result by 10 if the paper speed is 25 mm/sec or by 20 if the paper speed is 50mm/sec.

Paper Speed Settings

25 mm/sec: Each small box = 0.04 seconds, each big box = 0.2 seconds, 25 small boxes = 1 second
50 mm/sec: Each small box = 0.02 seconds, each big box = 0.1 seconds, 50 small boxes = 1 second

Sinus Rhythm

Depolarisation begins at the sinus node, the pacemaker of the heart.
In lead II, P waves should be positive, reflecting atrial depolarisation from the sinus node.
There should be a P wave for every QRS complex and consistent PR intervals.

Arrhythmia Definition

An arrhythmia is any alteration in heart rate, regularity, or normal activation sequence of the electrical heart activity
This includes abnormal origins for the electrical activation of the heart, irregular rate, and irregular beat intervals.

Arrhythmia Significance

Arrhythmias can result in cardiac injury from decreased cardiac output,
Especially when rhythms are too fast (tachycardia) or too slow (bradycardia),
Some specific arrhythmias (e.g., atrial fibrillation) affect atrio-ventricular synchrony potentially leading to sudden death.

Arrhythmia Classification

A clinically relevant scheme exists for classifying heart rhythm abnormalities, including both bradyarrhythmias (slow heart rates) and tachyarrhythmias (fast heart rates).
Bradyarrhythmias include sinus bradycardia, atrioventricular block, atrial standstill, and sick sinus syndrome.
Tachyarrhythmias include sinus tachycardia, atrial premature complexes, supraventricular tachycardia, atrial fibrillation, atrial flutter, ventricular premature complexes, accelerated idioventricular rhythm, ventricular tachycardia, and ventricular fibrillation.

Supraventricular vs. Ventricular Arrhythmias

Supraventricular arrhythmias originate from tissue above the ventricles (atria or AV junction).
Ventricular arrhythmias originate in the ventricles.
Ventricular arrhythmias are generally more dangerous due to potential consequences on cardiac output and function.
ECG characteristics distinguishing the origins include QRS complex shape and width, and the presence/absence of a preceding P wave.

Sinus Arrhythmia

Characterized by cyclic slowing and speeding of heart rate linked to respiration.
Considered a normal finding in many physiological states, but can be exaggerated by certain diseases or conditions.

Sinus Tachycardia

A sinus rhythm with a fast heart rate.
Rate cutoffs for diagnosis are species-specific: e.g., dogs >160 bpm; cats >200 bpm; horses >44 bpm; cattle >80 bpm.

Atrial Fibrillation (A-fib)

A disorganized atrial activity often associated with advanced heart disease in dogs and cats, or as a “lone” form in some cases.
Distinguished by an irregular or “sawtooth” baseline, absence of P waves, and often having a rapid heart rate.

Ventricular Premature Complexes (VPCs)

Abnormal impulses arising from the ventricles.
Often appear as “wide and bizarre” complexes with a missing preceding P wave.
Early development of VPCs, especially “R-on-T” phenomenon, increases risk for dangerous ventricular fibrillation.

Ventricular Tachycardia

A rapid heart rhythm arising from the ventricles characterized by four or more successive VPCs.
May be uniform (identical) or multiform (different in shape).
A dangerous rhythm often associated with dilated cardiomyopathy.

When to Treat Ventricular Arrhythmias

Single VPCs usually do not warrant treatment unless there are other concerns.
Evaluate for occult complex processes in patients with recurring, frequent, or unusually shaped VPCs.
Treat underlying causes (e.g., heart disease, electrolyte imbalances), or address other symptoms of cardiac compromise.

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Description

Test your knowledge on veterinary cardiology, focusing on ventricular premature complexes (VPCs) and ventricular tachycardia in dogs. This quiz covers causes, characteristics, risks, and treatment options associated with these arrhythmias. Perfect for veterinary students and professionals alike!