[2] Lecture 9: Cardiac Arrhythmias

Question 1

HR > 100bpm
And
Causes:

Answer 1

Tachycardia

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

Question 2

Endogenously mediated tachycardia:[exercise]

Answer 2

HR increase
CO increase
Filling time reduced but SV doesn’t decline

Question 3

Sympathetic stimulation when exercising maintains SV how?

Answer 3

Increase contractility
Systolic interval reduced
Increase venous return

Question 4

What are effects of pathologically mediated tachycardia?

Answer 4

HR increases

CO decreases

Question 5

Why do the effects of pathological mediated tachycardia occur?

Answer 5

MAP decreases and activates sympathetic NS after the fact and is unable to compensate

No muscle pump to increase venous return

Question 6

What is bradycardia and what causes it?

Question 7

Respiratory type of sinus arrhythmia

Answer 7

Medullary resp. Center into vasomotor center during inspiratory /expiration cycles….increase/ decrease HR through sympathetic and vagus nerves to the heart

Question 8

Sudden cessation of P waves- standstill of atria..ventricles pick up AV node rhythm. QRS pace is slower but not otherwise altered.

Answer 8

Sinoatrial block

Question 9

Ischemia of AV node or AV bundles through coronary insufficiency
Compression of AV bundles by scar tissue
Inflammation of AV node/bundle
Extreme stimulation of the heart by the vagus nerve

Answer 9

Atrioventricular block

Question 10

Extended PR interval:

Longer w/ slower HR
Shorter w/ faster HR

> .20s PR

Answer 10

1st degree AV block

Question 11

Extended PR that results in dropped beats of the ventricle

Answer 11

2nd degree AV degree

Question 12

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

Answer 12

Complete Atrioventricular block

Question 13

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

Answer 13

Ventricular escape

Question 14

Periodic fainting spells

Answer 14

Stokes-Adams syndrome

Question 15

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

Referred to as electrical alternans

Answer 15

Partial intraventricular block

Question 16

These heart beats occur before they should

Most result from ectopic focus

Answer 16

Premature contractions

Question 17

What causes ectopic foci:

Answer 17

Local ischemic areas
Calcified plaques
Irritation of the conduction system or nodes

Question 18

HR becomes rapid suddenly in bursts that last sec’s, min, hr’s, or longer
Then, ends suddenly

Answer 18

Paroxysmal tachycardia

Question 19

How can paroxysmal tachycardia resolve?

Answer 19

Pacemaker of heart instantly shifts back to the sinus node.

Question 20

The twitching of individual muscle fibers in the atria or ventricles and also in recently denervated skeletal muscle fibers

Occurs as a result of circus movements

Answer 20

Fibrillation

Question 21

3 different conditions that cause the impulse of heart to travel around the circle:

Answer 21

1-pathway around the circle is too long.
2-length of the pathway remains constant but the velocity of the conduction slows down.
3-refractory period of the muscle might become greatly shortened.

Question 22

A contraction or excitation wave traveling continuously in circular fashion around a ring of uncle or through the wall of the heart

Answer 22

Circus movements

Question 23

What condition generally causes circus movements d.t circle being too long

Answer 23

Enlarged/dilated heart

by the time the impulse returns to its starting point, the heart muscle will be in the refractory period.

Question 24

When the length of the pathway remains normal, but the conduction velocity is slowed down in heart. What 3 things could cause this?

Answer 24

1-blockage of purkinje system
2- ischemia*
3-high potassium levels

Question 25

What would cause the refractory period of the cardiac muscle to be shortened?

Answer 25

Rx: epinephrine
Or
Electrical stimulation

Question 26

The atrial muscle fibers are separated from ventricular muscle fibers by the:

Answer 26

cardiac fibrous skeleton

Question 27

Ventricular and atrial fibrillation can occur separate from each other

Answer 27

A fib

Question 28

Causes of A fib [2]:

Answer 28

Enlargement of atria-d/t valve lesions

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