Arrhythmias

Question 1

Ecchymosis

Answer 1

bruise, discoloured spot resulting from an accumulation of blood under the skin surface caused by an injury

Question 2

Ablation

Answer 2

• when they try to calm the rhythm of the heart by burning of some nerve fibres inside the heart
• they gain access to the heart by going through lungs and gaining access to pulmonary vessels

Question 3

Heart Arrhythmia

Answer 3

abnormal heart rhythm

Question 4

Three types of arrhythmias

Answer 4

bradycardia, tachycardia, and uncoordinated contractions

Question 5

Bradycardia

Answer 5

• slower than normal heart rate and is usually less than 60 bpm

Question 6

Tachycardia

Answer 6

• faster than normal heart rate and is usually more than 100 bpm

Question 7

Uncoordinated contractions

Answer 7

causes fibrilation

Question 8

list the two syndromes that can cause bradycardia

Answer 8

carotid sinus syndrome, and heart block

Question 9

How does carotid sinus syndrome cause bradycardia?

Answer 9

baroreceptors on the carotid artery are excessively sensitive which triggers a response from the vagus nerve, causing a domination of the vagal-Ach effects on the heart which then causes a decrease in heart rate (i.e. bradycardia)

Question 10

What are the two types of heart blocks that can lead to bradycardia?

Answer 10

SA block and AV block

Question 11

How can SA block lead to bradycardia?

Answer 11

• SA block is when impulses from the SA node to atrial muscle are blocked and so atrial contraction does not occur
• atrial contraction is depolarization which means there is an ending of the P wave

Question 12

How did AV block lead to bradycardia?

Answer 12

• AV block is when impulses through the Bundle of His is blocked which slows down impulse travel from atria to ventricle

Question 13

Where is electrical activity initiated in the heart?

Answer 13

SA node

Question 14

How do contractions start?

Answer 14

Electrical activity initiated at SA node is sent to the AV node which then makes its way to the Bundle of His which then sends it to the Purkinje fibres to cause coordinated contraction.

Question 15

Bachman’s bundle

Answer 15

responsible for coordinating the contraction of both the left and right atria, and the left and right ventricle

Question 16

What are the three key stages of the cardiac cycle?

Answer 16

P, QRS complex and T.

Question 17

What happens during P wave?

Answer 17

atria depolarization

- depolarization is the precursor to contracting of the heart

Question 18

What happens during the QRS complex?

Answer 18

• two events need to occur in order for the QRS complex to be generated: ventricle depolarization, and atria repolarization

Question 19

What happens during the T wave?

Answer 19

ventricle repolarization

- repolarization is the precursor to relaxing of the heart

Question 20

Paroxysmal tachycardia

Answer 20

tachycardia that happens suddenly

Question 21

two types of fibrillation that occurs as a result of paroxysmal tachycardia

Answer 21

supraventricular fibrillation (rapid heart beat in the atria or AV node) and ventricular fibrillation (rapid heart beat in the ventricle)

Question 22

Postural orthostatic tachycardia syndrome (POTS)

Answer 22

• difficulty adjusting to standing position from lying

- rapid heart beat (120bpm) within 10 minutes of standing

Question 23

Atrial fibrillation

Answer 23

chaotic electrical activity in the atria causing atria to quiver

Question 24

When is an individual diagnosed with Afib?

Answer 24

when AF duration is more than 30 seconds

Question 25

How does atrial fibrillation also lead to ventricular fibrillation?

Answer 25

it can lead to ventricular fibrillation as well because when atria contracts, blood flows from atria to ventricle and so irregular atrial contraction can affect blood flow

Question 26

two consequences of Afib

Answer 26

stroke (blood pools in your heart and forms clots which then travel to the brain) and heart attack (blood pools in your heart and forms clots)

Question 27

Atrial remodelling

Answer 27

- occurs when Afib remains untreated for a very long time | - this remodelling decreases the heart's ability to pump blood to the rest of the body

Question 28

What is the Virchow's triad?

Answer 28

risks and consequences of Afib - three parts: stasis (decreased blood flow), endothelial injury (damage to the inside of the blood vessel) and hypercoagulability (formation of more blood clots)

Question 29

difference between tachycardia and fibrilation

Answer 29

tachycardia is fast heart rate while fibrillation is chaotic heartbeat

Question 30

What happens during depolarization at the cardiomyocyte?

Answer 30

sodium channels open and sodium ions enter the cardiomyocyte

Question 31

What happens during the plateau stage at the cardiomyocyte?

Answer 31

sodium channels close, calcium channels open and calcium ions enter the cardiomyocyte. potassium channels open, potassium ions exit cardiomyocytes.

Question 32

What happens during repolarization at the cardiomyocyte?

Answer 32

calcium channels close. potassium channels stay open and potassium ions continue to exit cardiomyocyte

Question 33

Absolute refractory period

Answer 33

phase in which another action potential cannot be generated which is important because it allows for the heart to fully contract and fully pump blood

Question 34

Relative refractory period

Answer 34

phase in which another action potential can be generated if the stimulus is large enough

Question 35

What happens to the refractory period for people with atrial fibrillation?

Answer 35

the relative refractory period is altered. If we have activation of the sodium channels caused by maybe the presence of a hormone, this will cause another action potential to be generated. If this happens, the heart will not be able to fully relax, and expand before blood flows from atria to ventricles.

Question 36

Where is ablation treated?

Answer 36

left-atrium-pulmonary vein junction because this region has the highest autonomic nerve density

Question 37

Interatrial septum

Answer 37

Wall that allows for Bockman’s bundle to travel through in order to establish coordinated contraction between both atria’s and allows for communication between the sinoatrial node located in right atrium and left atrium of the heart

Question 38

Autonomic remodelling

Answer 38

when individuals experience increase in nerve growth factors (i.e. nerves start to grow) within one month of having a myocardial infarction

Question 39

How does autonomic remodelling link heart attack to atrial fibrillation?

Answer 39

Having a heart attack can decrease blood flow and eventually lead to cell death and tissue death of parts of the heart. In order to compensate for the tissue death, nerve endings will increase. The increase in nerve endings (i.e., nerve sprouting) can cause an increase in duration of atrial fibrillation.

Question 40

Hypertrophy

Answer 40

enlargement of the heart due to the increase in size of its cells (specifically enlarged interventricular septum and shrinking of the left ventricular space)

Question 41

Fibrosis

Answer 41

replacing healthy muscle cells with collagen and other matrix type proteins which decrease contractility and increase stiffness