Random.CardioReview

Question 1

Describe the phase of action potentials through heart: Phase 4

Answer 1

Resting membrane potential (Na-K pump and K leak)

Question 2

Describe the phase of action potentials through heart: Phase 0

Answer 2

Depolarization d/t rapid Na entry (slow Ca entry)

Question 3

Describe the phase of action potentials through heart: Phase 1

Answer 3

rapid/early repolarization (early & transient K exit)

Question 4

Describe the phase of action potentials through heart: Phase 2

Answer 4

Plateau d/t Ca entry and K exit (electrically balanced)

Question 5

Describe the phase of action potentials through heart: Phase 3

Answer 5

Repolarization d/t K continuing to exit; Ca entry stops

Question 6

Cardiac glycosides (ie digoxin) blocks Na-P pump and work on which phase of the cardiac action potential?

Answer 6

Phase 4
(Na-K pump and K leak channels)

Question 7

na channel blockers (eg, quinidine, lidocaine) work on what phase of the cardiac action potential?

Answer 7

Phase 0
(dpolarization occurs d/t rapid Na entry & slow Ca entry)

Question 8

The rate of Ca entry is responsible for (slow) depolarization of nodal cells) (phase 2 of cardiac action potential) affects what?

Answer 8

heart rate
conduction velocity
contractility

Question 9

Hyperkalemia causes what to electrocardiograms?

Answer 9

decreases repolarization time

–> shortens QT interval & see “tall & tented” T waves on ECG
–> delayed conduction velocity–> prolonged PR interval, prolonged QRS
***absent P waves

Question 10

What are hallmarks of atrial fibrillation on ECG?

Answer 10

1. no p waves
2. irregular chaotic rhythm
3. normal appearance of QRS complexes +/- tachycardia

Question 11

In an attempt to determine the underlying cause of arrhythmias– what is the acronym for diagnosis?

Answer 11

HEADS
H– heart dz–> cardiomyopathies, valvular dz, myocarditis, PE/cardiac neoplasia & any severe heart dz

E– electrolyte imbalance/metabolic dz–> K, Ca, Mg

A– Adrenergic tone/Autonomic imbalance–> stress, anxiety, pain, GI dz

D– Drugs/toxins–> catecholamines, digoxin/cardiac glycosides, antiarrhythmics

S– Surgical disease/ “usual suspects”–> splenic dz (benign or malignant), GDV, any severe systemic dz (pancreatitis, severe anemia, sepsis)

Question 12

Advanced 2nd degree AV block occurs when?

Answer 12

when multiple consecutive “dropped beats” occur
**multiple P waves not followed by QRS

Question 13

Describe how 3rd degree AV block looks on ECG?

Answer 13

-complete dissociation between P waves & QRS
-Pwaves at regular interval (normal/elevated rate)
-irreg QRS complexes
-P-R intervals variable
-WRS complexes normal (junctional) or abnormal (ventricular)

Question 14

Describe how atrial premature depolarizations (APDs) appear on ECG?

Answer 14

-early P waves
–irregular PP and RR interval
-PR interval: normal, dec or prolonged
-Variable P wave configuration

Question 15

Describe how atrial tachycardia appears on ECG?

Answer 15

-rapid, usually regular atrial rate
**most cases AV node is blocked, so normal ventricular rate with rapid atrial rate

Question 16

Describe how ventricular premature depolarizations appear on ECG?

Answer 16

–impulses originating in the ventricle, rather than sinus node
–QRS occurs earlier than normal sinus beat, w/o preceding P wave initiating depolarization
**look different from sinus QRS complexes
–T wave appears abnormal

Question 17

describe how ventricular tachycardia appears on ECG?

Answer 17

tachyarrythmia with the triggering impulse originating from the ventricles
– QRS complexes abnoraml
– dissociated from P waves
– T waves are abnormal
–atrial rate (P-wave) is slower than ventricular rate, often buried in QRS complexes
**not conducted across the AV node

Question 18

What are the differences between uniform and polymorphic VT

Answer 18

Uniform VT: RR interval is regular

Polymorphic VT: WRS differing configurations, RR interval is irregular

Question 19

Describe features of Torsades de pointes on ECG

Answer 19

specific type of wide complex tachycardia
-“twisting around the baseline”
-malignant arrhythmia

Question 20

List causes of advanced 2AVB

Answer 20

electrolyte imbalances
digitalis toxicity
AV nodal disease (inflammatory or degnerative)

Question 21

List examples of bradyarrythmias

Answer 21

-second degree AV block
-sinus arrythmia
- sinus bradycardia
-Sino-atrial (S-A) block & rest

Question 22

completed 3rd degree AV block is the commonly seen when?

Answer 22

foals with uroperitoneum

Question 23

What is definitive treatment of 3AVB?

Answer 23

-vagolytic drugs
- atropine or glycopyrrolate
-buscopan
-corticosteroids: dexamethasone
-Sympathomimetic drugs: speed idoventricular ryhtm– isoproterenol

Question 24

What is definitive treatmnet for 3AVB if medical management does not work?

Answer 24

pacemaker

Question 25

What are examples of tachyarrythmias?

Answer 25

supraventricular premature complexes (SVPCs) atrial tachycardia atrial flutter atrial fibrillation ventricular premature complexes idioventricular rythm vetnricular tachycardia

Question 26

Define bradyarrythmias in horses

Answer 26

heart rate less than 24 bpm

Question 27

most bradyarrhythmias are

Answer 27

physiological *8assoc with high vagal tone & abolished with excitment, exercise or vagolytic drugs

Question 28

Define sick sinus syndrome

Answer 28

sinus node dysfunction combined with C/S Sinus node dysfunction: abnormal automaticity and/or conduction within sinus node C/S: lethargy, weakness, exercise intolerance, nonsyncol or syncopal collapse

Question 29

What is the primary electrolyte disturbance associated with supression of normal sinus node function?

Answer 29

hyperkalemia

Question 30

What are drugs that can slow excitability of the SA node?

Answer 30

nondihydropyridine ca channel blockers (diltiazem) and beta-bockers

Question 31

When is 2AVB considered pathologic?

Answer 31

-- more than 2 dropped beats in a row over 24 hours(becomes advanced or high-grade block) -- persists despite excitement or exercise

Question 32

When should complete heart block be considered?

Answer 32

when atrial fibrillation if the ventricular rate is slow and regular

Question 33

define paroxysmal atrial fibrillation

Answer 33

self-terminates in 5 days

Question 34

What is the treatment of choice for quinidine-induced torsades de pointes (wide QRS tachycardia)?

Answer 34

administer MgSO4 (1-2.5 g/450 kg/minute rapidly IV to effect or up to 25 gms/450 ks)

Question 35

what is the most common presenting C/S with atrial fibrillation?

Answer 35

exercise intolerance or poor performance