Causes of Arrhythmias (Exam IV)

Question 1

How does general anesthesia precipitate arrhythmias?

Answer 1

By Inhibiting reuptake of NE.

Question 2

How do local anesthetics precipitate arrhythmias?

Answer 2

Only precipitative if -caine derivatives spread to the heart.

Question 3

How does vagal stimulation precipitate arrhythmias?

Answer 3

“5 & Dime Reflex”

Question 4

How does intubation precipitate arrhythmias?

Answer 4

Laryngeal pressure sensors can cause missed beats.

Question 5

How does physical contact with the heart precipitate arrhythmias?

Answer 5

Cardiac irritation during open heart surgery

Question 6

How do changes in ventilatory rate precipitate arrhythmias?
Why is this?

Answer 6

↑ resp rate = ↓ ECF Ca⁺⁺
- Loss of H⁺ in blood means Ca⁺⁺ gets attached to negatively charged proteins.

Question 7

How do central line insertions precipitate arrhythmias?

Answer 7

Central lines can irritate the endocardium & causes missed beats.

Question 8

How can changes in body temperature precipitate arrhythmias?

Answer 8

• ↑ Temp = Tachy
• ↓ Temp = Brady

Question 9

How do MI’s precipitate arrhythmias?

Answer 9

Through scar tissue formation, ischemia, etc.

Question 10

How do hypertrophic atria precipitate arrhythmias?

Answer 10

↑ atrial stretch = ↑ HR by direct Na⁺ & K⁺ channel permeability to stretch.

Question 11

What are the two mechanism’s by which atrial stretch achieves heart rate increase?
What percentage of heart rate increase comes from each?

Answer 11

1. Direct Atrial Stretch (↑HR by 10 - 15%)
2. Bainbridge Reflex (↑HR by 50%)

Question 12

How does the Bainbridge Reflex work?

Answer 12

Increased atrial stretch causes nervous system sensors on nodal tissue to inhibit vagal innervation thus ↑ HR.

Question 13

Why would removal of a β blocker that a patient has been taking for a long time cause arrhythmias?

Answer 13

Chronic β-blocker usage = upregulated β receptors.

Question 14

Why would removal of Ca⁺⁺ Channel Blocker that a patient has been taking for a long time cause arrhythmias?

Answer 14

Upregulation of Ca⁺⁺ channels occurs with chronic CCB use.

not as serious as equivalent scenario with βblocker

Question 15

What is the purpose of catecholamine ligand β receptor?
When does this become particularly important?
How does a β blocker affect this process?

Answer 15

• NE bound β receptors speed up Na⁺ K⁺ ATPase pump to help push ECF K⁺ back intracellularly.
• Important during exercise or strenuous activity.
• A β blocker would increase ECF K⁺ because Na⁺ K⁺ ATPase pump wouldn’t work as fast.

Question 16

How would insulin affect K⁺ levels?

Answer 16

• Insulin bound to its receptor would speed up Na⁺ K⁺ ATPase pumps and move K⁺ from the ECF to the ICF.