Rhythm of the Heart

Question 1

Which conductive region of the heart is influenced by Parasympathetic and Sympathetic activity?

Answer 1

Sinus / Sinoatrial node

Question 2

What is the “safety mechanism” of the Atrio-ventricular node?

Answer 2

Prevents high atrial rates being transmitted directly to the ventricles

Question 3

What does the PR interval represent in the cardiac conduction pathway?

Answer 3

Reflects conduction through the Atrio-ventricular node

Question 4

What does the QRS complex represent in the cardiac conduction pathway?

Answer 4

Reflects conduction through the ventricular myocardium

Question 5

What is a normal PR interval in msec?

Answer 5

120 - 200 msec

Question 6

What is a normal QRS interval in msec?

Answer 6

< 110 msec

Question 7

What is normal sinus rhythm in adults and in children?

Answer 7

In adults: 60 - 100

In children: 100 - 120

Question 8

What is fainting medically known as?

Answer 8

Vasovagal syncope

Question 9

What is the effect of increased PNS activity on heart rate?

Answer 9

Decreases heart rate

Question 10

What is the effect of increased SNS activity on heart rate?

Answer 10

Increases heart rate

Question 11

What is the effect of decreased SNS activity on heart rate?

Answer 11

Decreases heart rate

Question 12

What is the effect of decreased PNS activity on heart rate?

Answer 12

Increases heart rate

Question 13

What is the effect of Adrenaline on HR?

Answer 13

Increases HR by increasing sympathetic activity

Question 14

What is the effect of Salbutamol on HR?

Answer 14

Increases HR by increasing sympathetic activity

Question 15

What is the effect of Beta-blockers on HR?

Answer 15

Decreases HR by decreasing sympathetic activity

Question 16

What is the effect of Atropine on HR?

Answer 16

Increases HR by decreasing parasympathetic activity

Question 17

What is Bradycardia defined as?

Answer 17

Heart rate less than 60 bpm

Question 18

Atleast how many squares would seperate every QRS complex in Sinus Bradycardia?

Answer 18

300 / 60 = Atleast 5 squares

Question 19

No more than how many squares would seperate every QRS complex in Sinus Tachycardia?

Answer 19

300 / 100 = No more than 3 squares

Question 20

On an ECG, there are regular QRS complexes, spaced 6 squares apart. There is P wave in front of each QRS complex with normal delay. What does this mean?

Answer 20

Sinus Bradycardia

Question 21

On an ECG, there are regular QRS complexes, spaced 6 squares apart. There is no P wave in front of each QRS complex with normal delay. What does this mean?

Answer 21

Heart block

Question 22

On an ECG, there are irregular QRS complexes, spaced 7 squares apart. There are no P wave in front of each QRS complex with normal delay. What does this mean?

Answer 22

Slow atrial fibrillation

Question 23

What is Brady-Tachy syndrome?

Answer 23

Intermittent episodes of slow and fast heart rates

Question 24

How do we treat Brady-Tachy syndrome?

Answer 24

For the Bradycardia aspect: Pacemaker to speed up HR

For the Tachycardia aspect: Drugs to slow down HR

Question 25

What are some causes for Sinus Bradycardia?

Answer 25

Athlete fitness Certain medications which slow down heart rate, i.e. Calcium channel blockers, Beta blockers, Digoxin Hypothyroidism

Question 26

Of LBBB and RBBB, which one could be benign?

Answer 26

RBBB

Question 27

On an ECG, there are regular QRS complexes, spaced 3 squares apart. The complexes are < 120 msec wide, and the HR is < 120 bpm. What does this mean?

Answer 27

Sinus Tachycardia (ST)

Question 28

On an ECG, there are regular QRS complexes, spaced 3 squares apart. The complexes are >120 msec apart. What does this mean?

Answer 28

Ventricular Tachycardia (VT)

Question 29

On an ECG, there are irregular QRS complexes, spaced 3 squares apart. What might this mean?

Answer 29

Atrial Fibrillation

Question 30

How can you differentiate between Ventricular Tachycardia and Supraventricular Tachycardia?

Answer 30

Inject Adenosine, which blocks the atria. In SVT, the heart rate will slow down. In VT, it will not

Question 31

What is the heart rate in Atrial Flutter?

Answer 31

300 bpm

Question 32

What can exacerbate Torsades de Pointes?

Answer 32

Class I anti-arrhythmic drugs, and low K and low Mg

Question 33

What is the treatment for Torsades de Pointes?

Answer 33

IV Magnesium

Question 34

On an ECG, there are regular QRS complexes, spaced 3 squares apart. The complexes are < 120 msec wide, and the HR is > 140 bpm. What does this mean?

Answer 34

Supraventricular Tachycardia