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Whitney - Physiology Test 2 > Lecture 8 Cardiac Arrhythmias > Flashcards

Lecture 8 Cardiac Arrhythmias Flashcards

1
Q

Which of the following conditions may result in tachycardia?

a. Toxic conditions of the heart
b. Increased body temp.
c. Sympathetic nerve stimulation
d. All of the Above
e. B and C only

A

d. All of the Above

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2
Q

Circus movements are the basis of heart fibrillation. Which of the following statements is not true? a. Fibrillation may occur when the refractory period of the muscle is greatly shortened b. Fibrillation may occur when the pathway around the circle is too short c. Fibrillation may occur when the conduction velocity slows down d. Fibrillation may occur when the heart becomes dilated

A

b. Fibrillation may occur when the pathway around the circle is too short

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3
Q

What is the definition of Tachycardia?

A

Fast heart rate (> 100 beats/min)

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4
Q

What are the causes of Tachycardia?

A

Increased body temp Stimulation of the heart by sympathetic nerves Toxic conditions of the heart

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5
Q

The results of Endogenously Mediated Tachycardia (i.e. exercise) include:

A

Increased HR Increased cardiac output Reduced filling time, but stroke-volume does not fall (ejection fraction increases)

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6
Q

The results of Pathologically mediated tachycardia include:

A

Increased HR Decreased cardiac output

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7
Q

What is the definition of Bradycardia?

A

Slow heart rate (

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8
Q

What are the causes of Bradycardia?

A

Athletic heart Vagal stimulation Extremely sensitive carotid baroreceptors in carotid sinus syndrome

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9
Q

Identify the ECG

A

Sinus Bradycardia

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10
Q

What type of signals alternately increase and decrease number of impulses transmitted through sympathetic and vagus nerves to the heart?

A

Spillover signals

From medullary repiratory center into vasomotor center during inspiratory and expiratory respiratoty cycles

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11
Q

What is this called?

A

Sinus Arrhythmia

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12
Q

Characteristics of Sinoatrial Block (5):

A

Sudden cessation of P waves

Resultant standstill of atria

Ventricles pick up a new rhythm, usually originating in the AV node

Rate of QRS is slowed but not otherwise altered

Ventricles will still fill but won’t have last third of pumping effect from atria

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13
Q

Identify the ECG

A

Sinatrial nodal black (lead III)

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14
Q

What are conditions that cause atrioventricular blockage?

A

Ischemia of AV node or AV bundle fibers through coronary insufficiency

Compression of AV bundle by scar tissue or clacified portions of the heart

Inflammation of the AV node or bundle

Extreme stimulation of the heart by the vagus nerve

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15
Q

What are the two types of incomplete atrioventricular block?

A

First-degree

Second-degree

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16
Q

What is the normal P-R time interval?

A

0.16 sec

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17
Q

What determines if a patient has a first degree incomplete heart block?

A

When the P-R interval increases to geater than 0.20 seconds

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18
Q

What determines a Second-Degree block?

A

P-R time intercal increases to 0.25 to 0.45 secs

Atrial P wave is present but QRS-T wave may be missing, resulting in dropped beats of the ventricle

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19
Q

Identify the ECG

A

Prolonged P-R interval (first degree A-V heart block) (lead II)

20
Q

Identify the ECG

A

Second degree A-V block

21
Q

Describe what happens in a complete atrioventricular block

(WARNING: Very wordy)

A

Ventricles establish their own signal

No relation between rate of P waves and rate of QRS-T complexes

Duration of block is highly variable (secs to weeks)

After AV conduction ceases, ventricles may not start beating on their own for 5-30 secs

Resumption of the ventricular beat may be due to parts of the Purkinje system acting as an ectopic pacemaker

Patients often faint due to lack of blood to brain until ventricles escape

22
Q

The periodic fainting spells are reffered to as

A

Stokes-Adams Syndrome

23
Q

Identify the ECG

A

Complete A-V block

24
Q

A partial intraventricular black is referred to as what?

A

“electrical alternans”

25
Q

What does the term “electrical alternans” refer to?

A

An alteration in the amplitude of P waves, QRS complexes, or T waves

26
Q

Identify the ECG

A

Partial Intraventircular Block (electrical alternans)

27
Q

Most premature contractions are the result of:

A

ectopic foci

28
Q

Give examples of ectopic foci (3)

A

Local ischemic areas

Calcified plaques

Irritation of the conduction system or nodes

29
Q

Identify the ECG

A

Atrial Premature Beat

30
Q

Identify the ECG

A

A-V nodal premature contraction

31
Q

Define Paroxysmal Tachycaradia

A

Heart becomes rapid in paroxysms

32
Q

Identify the ECG

A

Atrial paroxysmal tachycardia

33
Q

Identify the ECG

A

Ventricular paroxysmal tachycardia

34
Q

Explain the Basis for Fibrillation

A

The normal ventricular depolarization waves die out because the heart muscle that has already contracted is in the refractory period and cannot respond to being stiumlated by the existing depolarization waves

35
Q

What is Fibrillation?

A

Twitching (usually slow) of individual muscle fibers in the atria or ventricles and also in recently denervated skeletal muscle fibers

36
Q

What causes fibrillation?

A

Fibrillation occurs as a result of circus movements

37
Q

What is a circus movement?

A

When the impuls travels around in a circle

38
Q

Name three different conditions that cause circus movements

A

The pathway around the circle is too long

The length of the pathway remains constant but the velocity of the conduction slows down

The refractory period of the muscle might become greatly shorteded

39
Q

Explain a how the length of the pathway around the circle (ventricles) being too long can create a circus movement

A

When a pathway is too long, often because of a dilated heart, the impulse takes longer to get back to the starting point, and the muscle is no longer in its refractory period and can therefore undergo another depolarization

40
Q

What can be the cause of a circus movement occuring because of a slowed velocity (but same length pathway)?

A

Blockage of Purkinje system, ischemia, or high potassium levels

41
Q

What can be the cause of a circus movement occuring due to a shortened refractory period?

A

May occur in response to drugs such as epinephrine

May occur after repetitive electrical stimulation

42
Q

Identify the ECG

A

Ventricular fibrillation

43
Q

Atrial Fibrilation

A

The atrial muscle fibers are separated from the ventricular muscle fibers by the cardiac fibrous skeleton

May occur seperate from ventricular fibrillation

44
Q

Causes of atrial fibrillation

A

Enlargement of the atria (i.e. due to valve lesions)

Inadequate emptying of the ventricles causing blood to back up into the atria

45
Q

Identify the ECG

A

Atrial Fibrillation

Whitney - Physiology Test 2 (8 decks)

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