Arrhythmias *

Question 1

What’s bradycardia?

Answer 1

Abnormally slow rhythms.

Question 2

What’s tachycardia?

Answer 2

Abnormally fast rhythm.
Supraventricular – involving AV node
Ventricular – involving His-Purkinje system

Question 3

What’s the native pacemaker?

Answer 3

SA node. It sets the heart rate.

Question 4

What’s a latent pacemaker?

Answer 4

Harbours potential to act as pacemakers if needed.

Question 5

What’s overdrive suppression?

Answer 5

Cells with the fastest rhythm dominate and directly suppress other automatic cells.

Question 6

What 3 factors determine the intrinsic firing rate of the conduction pathway?

Answer 6

• Rate of phase 4
• Maximum Negative RMP
• Threshold Potential

Question 7

What are the main abnormalities of impulse initiation that leads to arrhythmias?

Answer 7

• altered automatic
• abnormal automaticity
• triggered activity

Question 8

What happens when there’s increased SA automaticity?

Answer 8

There’s a steeper depolarization during phase 4. AP is shifted to a more negative voltage, reaching threshold earlier.

It’s controlled by the automatic nervous system. (Sympathetic Nervous System)

Question 9

What happens when there’s decreased SA automaticity?

Answer 9

There’s a more gradual and longer phase 4 depolarization. There’s a more negative diastolic potential. Less negative threshold potential.

It’s controlled by reduced sympathetic and increased parasympathetic.

Question 10

What’s an escape beat?

Answer 10

It’s an impulse initiated by a latent pacemaker - due to a slow SA node rate.

Question 11

What’s an escape rhythm?

Answer 11

It’s a continued series of escape beats due to persistently impaired SA node.

Question 12

Increased PNS yields what?

Answer 12

At the SA node leads to decreased Simms activity. So AV node takes over. Ventricular pacemaker sites take over.

Question 13

What’s an ectopic beat?

Answer 13

It’s an enhanced impulse firing in a latent pacemaker.

Question 14

What’s ectopic rhythm?

Answer 14

It’s a sequence of ectopic beats.

Question 15

What’s the difference between an ectopic beat and an escape beat?

Answer 15

An ectopic beat is a premature impulse whereas an escape beat is late neared which terminated a pulse caused by slow sinus rhythm.

Question 16

What’s abnormal automaticity?

Answer 16

Arise from cells that do not usually possess automaticity. Myocardial cells outside of the specialized conduction system acquire automaticity and spontaneously depolarize

Question 17

What is triggered activity?

Answer 17

occurs when an action potential triggers an abnormal depolarization which results in an extra heartbeat. Abnormal action potentials occur if the after depolarization reaches a threshold voltage

Question 18

What is a conduction block?

Answer 18

It’s when the propagating impulse is blocked when it encounters an electrically unexcitable region in the heart

Question 19

What is a functional block?

Answer 19

It’s a block that occurs when the impulse encounters cells in the refractory period

Question 20

What’s the fixed block?

Answer 20

It’s a conduction block imposed by fibrosis or scarring that replaces myocytes.

Question 21

What is Wolf Parkinson White syndrome?

Answer 21

It’s bypassing the path referred to as the bundle of Kent. It causes conduction to occur faster than with the AV node, resulting in a shortened PR interval and the QRS complex becomes wider since the spread of the impulse is shortened.

Question 22

What happens when you have sinus bradycardia?

Answer 22

There’s decreased firing of SA node at rest or during sleep. Can result from either intrinsic SA node disease or extrinsic factors affecting the SA node.

Question 23

What’s sick sinus syndrome?

Answer 23

It’s intrinsic SA node dysfunction. Causes periods of bradycardia and in some individuals, tachycardia as well.

Question 24

What’s junctional escape rhythm?

Answer 24

Arises from AV node and bundle of his. There’s no P wave. HR of 40-60 bpm.

Question 25

What’s ventricular escape rhythm?

Answer 25

Depolarization occurs from a more distal site. Characterized by wider QRS complex. Rate of 30-40 bpm.

Question 26

What’s first degree AV block?

Answer 26

It’s a prolonged delay at AV node resulting in lengthened PR interval.

Question 27

What’s second degree AV block?

Answer 27

It’s intermittent failure of AV conduction. Some P waves are not followed by QRS complex.

Question 28

What’s third degree AV degree block?

Answer 28

It’s a complete heart block with no electrical communication between atria and ventricles.

Question 29

What are the supraventricular tachyarrhythmias?

Answer 29

Sinus Tachycardia, atrial premature beats, atrial flutter, and atrial fibrillation.

Question 30

What’s sinus tachycardia?

Answer 30

It’s a supraventricular arrhythmia that caused SA node discharge. Results in increased sympathetic activity.

Question 31

What’s atrial premature beats?

Answer 31

It originates from automaticity or reentry into atrial focus outside of the SA node

Question 32

What’s atrial flutter?

Answer 32

It’s rapid regular atrial activity at a rate of 180-350 bpm. P wave is saw tooth shaped.

Question 33

What’s atrial fibrillation?

Answer 33

It’s chaotic rhythm with a rate of 350-600 bpm. P waves aren’t found in ECG. It involves multiple re-entrant circuits. It’s associated with enlarged right or left atrium.

Question 34

What are ventricular arrhythmias?

Answer 34

More dangerous than supraventricular. There’s ventricular premature beats, ventricular tachycardia, and ventricular fibrillation.

Question 35

What’s Ventricular Premature Beats?

Answer 35

Occurs when an ectopic ventricular focus fires an AP.

Question 36

What’s sustained VT?

Answer 36

It’s longer than 30 seconds, produces severe symptoms, or requires termination by drugs or cardioversion.

Question 37

What’s nonsustained VT?

Answer 37

Self-terminating episodes. QRS complex is wider.

Monomorphic- QRS complexes appear the same and the rate is regular.

Polymorphic - complex continues to change shape and the rate varies.

Question 38

What’s ventricular fibrillation?

Answer 38

Disordered, rapid stimulation of the ventricles without coordinated contraction.

Question 39

What are the four signs of infarction?

Answer 39

1) ST segment elevation.
2) T wave inversion
3) Q waves >40 ms, >2 mm deep
4) reciprocal ST segment depression

Question 40

What’s is ST elevation specifically?

Answer 40

Myocardial infarction

Question 41

What is ST depression specifically?

Answer 41

myocardial ischemia.