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Physiology I (Exam II material) > Lecture 8 Cardiac Arrhythmias > Flashcards

Lecture 8 Cardiac Arrhythmias Flashcards

1
Q

Tachycardia

A

Fast Heart rate (>100 beats/min)

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2
Q

What causes Tachycardia

A

Increased body temperature stimulation of the heart by sympathetic nerves Toxic conditions of the heart

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3
Q

How much does heart rate increase with body temperature

A

Increases about 10 beats per degree F increases about 18 beats per degree C

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4
Q

The heart may be stimulated by the sympathetic nerves for increase heart rate due to what

A

loss of blood and/or decreased state of shock

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5
Q

During endogenously mediated tachycardia does stroke volume fall

A

No

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6
Q

What happens during endogenously mediated tachycardia (i.e. Exercise)

A

Heart rate increases, Cardiac output increases, filling time is reduced but stroke-volume does not fall

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7
Q

what happens during pathologically mediated tachycardia

A

heart rate increases, cardiac output decreases

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8
Q

Bradycardia

A

HR less than 60 beats/min

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9
Q

What are some causes of Bradycardia

A

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

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10
Q

What are respiratory type of Sinus arrhythmia: Spillover signals

A

form medullary respiratory center into vasomotor center during inspiratory and expiratory respiratory cycles - these signals alternately increase and decrease number of impulses transmitted through sympathetic and vagus nerves to the heart

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11
Q

What kind of block causes a sudden cessation of the P wave

A

Sinoatrial block

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12
Q

What are the characteristics of a sinoatrial block

A

Sudden cessation of the 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

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13
Q

what are some conditions that cause an Atrioventricular block

A

-Ischemia of AV node or AV bundle fibers through coronary insufficiency - Compression of AV bundle by scar tissue or calcified portions of the heart - Inflammation of the AV node or bundle - Extreme Stimulation of the heart by the vagus nerves

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14
Q

Characteristics of a Incomplete First-Degree AV block

A

The P-R interval is increased to greater than 0.20 seconds

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15
Q

Characteristics of a incomplete second-degree AV block

A

P-R interval is increased to 0.25 to 0.45 seconds Atrial P wave is present but QRS-T wave may be missing, resulting in dropped beats of the ventricle 2:1 rhythm or other variations may develop

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16
Q

Characteristics of Complete AV block

A
  • ventricles establish their own signal (usually AV node) - No relation between the rate of the P waves and the rate of the QRS-T complexes - Duration of the block is highly variable (seconds to weeks) - After AV conduction ceases, ventricles may not start beating on their own for 5 to 30 seconds - Resumption of the ventricular beat (=ventricular escape) may be due to parts of the Purkinje system acting as an ectopic pacemaker - after a complete block occurs, patients will often faint due to lack fo blood to the brain until the ventricles escape - These periodic fainting spells are referred to as Stokes-Adams syndrome
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17
Q

what is Ventricular escape

A

Resumption of the ventricular beat

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18
Q

what may lead to ventricular escape

A

Parts of the Purkinje system acting as an ectopic pacemaker

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19
Q

After AV conduction ceases, ventricles may not start beating on their own

A

for 5-30 seconds

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20
Q

What is Stokes-Adam Syndrom

A

Period fainting spells due to lack of blood to brain secondary to complete AV block

21
Q

What is a partial Intraventricular block normally referred to as

A

Electrical Alternans

22
Q

what is a Electrical alternans

A

Partial intraventricular block an alternation in the amplitude of P waves, QRS complexes, or T waves

23
Q

What are premature contractions

A

Contractions that occur before they should

24
Q

What are the main causes of premature contractions

A

Ectopic foci: - Local ischemic areas - Calcified Plaques - Irritation of the conduction system or nodes

25
Q

What is Paroxysmal Tachycardia, how long does it last, and how does it end?

A

Heart becomes rapid in paroxysms paroxym begins suddenly and lasts for a few seconds, minutes, hours, or longer Paroxysm ends suddenly Pacemaker of the heart instantly shifts back to the sinus node

26
Q

Each block on the x-axis is how many seconds

A

0.2 seconds, each smaller block is 0.04 seconds

27
Q

Each large block on the x-axis is how many mV

A

0.5 mV, each smaller block is 0.1mV

28
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.

29
Q

Fibrillation occurs as a result of what

A

circus movements

30
Q

What are the 3 different conditions that case the impulse to travel around the circle

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 shortened
31
Q

What is the effect of the pathway around the circle (ventricles) being too long

A

The impulse takes longer to get back to its starting point, and the muscle is no longer in its refractory period and can undergo another depolarization

32
Q

When causes the length of the pathway to remain normal, but the conduction velocity of the impulse is slowed down

A

Usually occurs because of the blockage of the Purkinje system, ischemia, or high potassium levels

33
Q

What may cause the refractory period of the muscle to shorten

A

may occur in response to drugs such as epinephrine may occur after repetitive electrical stimulation

34
Q

What are some causes of atrial fibrillation

A

Enlargement of the atria ( due to valve lesions) -Inadequate emptying of the ventricles causing blood to back up into the atria

35
Q

Atrial muscle fibers are separated from the ventricular muscle fibers by the __________

A

Cardiac fibrous skeleton

36
Q

Can ventricular and atrial fibrillation occur separate form one another

A

Yes

37
Q
A

Bradycardia

38
Q
A

Sinoatrial block

39
Q
A

First degree A-V block

(Prolonged P-R interval)

40
Q
A

Second degree A-V block

(Prolonged P-R interval with Dropped beat)

41
Q
A

Complete A-V block

(no relation between the rate of the P waves and the rate of the QRS-T complexes)

42
Q
A

Partial intraventricular block (electrical alternans)

(Alternation in the amplitude of the Pwaves, QRS complexes, or T waves)

43
Q
A

Atrial premature beat

44
Q
A

A-V nodal premature contraction

45
Q
A

Atrial paroxysmal tachycardia

46
Q
A

Ventricular paroxysmal Tachycardia

47
Q
A

Atrial Fibrillation

48
Q
A

Ventricular fibrillation

Physiology I (Exam II material) (9 decks)

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