AV Block and Ventricular Arrhythmias Flashcards

1
Q

What are the characteristics of first degree AV block?

A

Normal P wave
Prolonged PR interval
Normal QRS complex and rest of conduction

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2
Q

What is another name for first degree AV block?

A

Prolonged AV conduction

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3
Q

Define second degree AV block

A

Some atrial impulses fail to conduct to the ventricles (lonely P wave)

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4
Q

What are the two types of second degree AV block?

A

Mobitz type I (Wenkebach - physiologic)

Mobitz type II (pathologic)

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5
Q

How can Mobitz type I be distinguished from Mobitz type II second degree AV block?

A
Type I
2:1 conduction
Asymptomatic
Associated with high vagal tone
Responds to atropine
Will speed and slow based sympathetic and parasympathetic innervation
Remove underlying cause to treat
Type II
 >2:1 conduction
Symptoms vary based on degree of block
Structural dz of AV node often present
Partially responsive to atropine
May require pacemaker
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6
Q

How is the Atropine response test conducted?

A

.04 mg/kg IV, wait 5-10 min for response (usually sooner); if HR >180 without further block, secondary to high vagal tone; if HR not >180 or persistent block, AV nodal dz, pacemaker needed

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7
Q

What is third degree AV block?

A

Complete failure of AV node conducion

Some part of conduction system must take over as pacemaker

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8
Q

How does level of block in third degree AV block affect ECG readout?

A

If at AV node, junctional escapes with narrow QRS complexes will be present
If at His-purkinje level, ventricular escapes with wide QRS complexes

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9
Q

What are some clinical signs associated with third degree AV block?

A
Collapse or fainting
Heart failure (left or right sided)
GI signs, weakness, lethargy, azotemia (loss of forward flow)
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10
Q

How is third degree AV block treated?

A

Pacemaker

Isoproterenol IV infusion

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11
Q

What is an ectopic beat?

A

One that arises from an area other than the SA node; can be early or late

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12
Q

What is a Premature venticular complex (PVC)?

A

It is a conduction that has a much wider QRS wave and overall different appearance from sinus conduction

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13
Q

What is bigeminy?

A

Each normal conduction is followed by an abnormal one; may be atrial or ventricular

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14
Q

What is a fusion beat?

A

Combination of supraventricular (sinus) complex and PVC

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15
Q

What are some causes of VPCs?

A
Primary cardiac disease
Metabolic/Endocrine disorders
Drugs/Toxins (Digoxin, Amphetamine, Theobromine)
GDV
Sepsis
Splenic disease
Hypoxia
Hypovolemia
Pain
Trauma
Autonomic imbalance (increased sympathetic)
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16
Q

What is accelerated idioventricular rhythm?

A

Pts who are septic, hypovolemic, etc. go between sinus and ventricular arrhythmia

17
Q

How are PVCs treated?

A

Address the underlying disease

Lidocaine (1B) or procainamide (1A)

18
Q

What does sustained ventricular tachycardia look like on an ECG strip?

A

Wide, saw tooth pattern (ventricular flutter)

19
Q

In what instances would you see sustained ventricular tachycardia?

A

Boxers with arrhythmogenic right ventricular cardiomyopathy
Doberman with dilated cardiomyopathy
Myocarditis (Chagas dz)

20
Q

What are some hemodynamic consequences of arrhythmias?

A
Decreased cardiac function
Drop in blood pressure
Reduced tissue perfusion
Limited exercise capacity
Syncope
21
Q

What are some electrical instability consequences of arrhythmias?

A

Myocardial fibrillation
Asystole
Sudden cardiac death

22
Q

How is ventricular fibrillation treated?

A

Defibrillation

Magnesium (.2mEq/kg IV)

23
Q

What drugs are available for treatment of ventricular dysrhytmia?

A
Lidocaine
Procainamide
Amiodarone
Magnesium salts
Quinidine NG
Phenytoin
Direct current cardioversion
At home:
Sotalol
Procainamide
Amiodarone
Atenolol
Mexilitine