Lecture 5 8/23/24

Question 1

How does the shape of the QRS complex vary based on origin?

Answer 1

supraventricular origin: narrow
ventricular origin: wide, bizarre

Question 2

What is tachyarrhythmia?

Answer 2

any deviation from sinus rhythm that is characterized by rapid rate

Question 3

What does the term supraventricular refer to?

Answer 3

atrial and junctional depolarizations

Question 4

Why does supraventricular tachyarrhythmia present with a narrow QRS?

Answer 4

depolarization arises proximal to the bifurcation of the bundle of His

Question 5

What are the characteristics of supraventricular premature complexes?

Answer 5

-occur early
-have a narrow QRS
-associated with diseases that cause atrial distention

Question 6

What are the characteristics of supraventricular tachycardia?

Answer 6

-usually regular
-start and stop abruptly
-QRS narrow
-3 or more early complexes
-pathologic, not physiologic

Question 7

What are the characteristics of atrial fibrillation?

Answer 7

-rapid
-irregular
-monomorphic w/ narrow QRS
-no P waves
-abrupt RR interval changes w/ no pattern
-associated with diseases that result in atrial distention

Question 8

Why is atrial fibrillation only seen in larger animals?

Answer 8

the heart has to be large in order for atrial fib. to develop

Question 9

What are the characteristics of ventricular premature complexes?

Answer 9

-occur early
-wide and bizarre QRS
-associated with structural heart disease or non-cardiac disease (dogs)
-no P wave

Question 10

What are the characteristics of ventricular tachycardia?

Answer 10

-three or more successive ventricular ectopic complexes at a rapid rate
-regular
-initiated by a ventricular premature complex
-associated with structural disease

Question 11

What is the significance of ventricular tachycardia?

Answer 11

-can cause signs of low output
-can degenerate to ventricular fib.
-prodrome of severe myocardial dysfunction

Question 12

What extra-cardiac diseases can cause ventricular tachyarrhythmia?

Answer 12

-trauma
-GDV
-splenic disease
-neurologic disease
-sepsis

Question 13

What are the potential etiologies of ventricular tachyarrhythmia in extra-cardiac disease?

Answer 13

-autonomic factors
-electrolyte disturbances
-acid-base disturbances

Question 14

How do ventricular tachyarrhythmias in extra-cardiac disease differ from those caused by cardiac disease?

Answer 14

-slow/less than 160 bpm
-initiated by late diastolic ventricular complexes
-well tolerated by patient
-electrically benign
-resolve spontaneously

Question 15

What is a 1st degree AV block?

Answer 15

PR interval prolongation

Question 16

What is a 2nd degree AV block?

Answer 16

-intermittent failure of AV conduction
-one or more P waves fails to conduct to ventricles

Question 17

What is a 3rd degree AV block?

Answer 17

-complete failure of AV conduction
-slow idioventricular “escape rhythm” is responsible for wide QRS complexes that are independent of atrial depolarizations

Question 18

What are the potential types of 2nd degree AV block?

Answer 18

-functional/related to elevated vagal tone
-AV node disease

Question 19

What are the characteristics of high grade 2nd degree/3rd degree AV block?

Answer 19

-results from intrinsic conduction system disease
-causes syncope and/or exercise intolerance
-can cause CHF and sudden death
-results from idiopathic fibrosis
-associated with myocardial disease and aortic valve endocarditis
-important indication for cardiac pacing

Question 20

What are the characteristics of sick sinus syndrome?

Answer 20

-sinus pauses or bradycardia
-manifest as syncopal episodes

Question 21

How does severe hyperkalemia impact the heart?

Answer 21

-bradyarrhythmia
-wide QRS
-low amplitude/absent P waves
-peaked T waves

Question 22

What are the consequences of arrhythmias?

Answer 22

-syncope and possible sudden death
-poor perfusion in critically ill patients

Question 23

How are arrhythmias treated?

Answer 23

-pharmacologically for tachyarrhythmias
-cardiac pacing for bradyarrhythmias