Arrhythmias * Flashcards

1
Q

What’s bradycardia?

A

Abnormally slow rhythms.

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2
Q

What’s tachycardia?

A

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

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3
Q

What’s the native pacemaker?

A

SA node. It sets the heart rate.

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4
Q

What’s a latent pacemaker?

A

Harbours potential to act as pacemakers if needed.

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5
Q

What’s overdrive suppression?

A

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

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6
Q

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

A
  • Rate of phase 4
  • Maximum Negative RMP
  • Threshold Potential
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7
Q

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

A
  • altered automatic
  • abnormal automaticity
  • triggered activity
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8
Q

What happens when there’s increased SA automaticity?

A

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)

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9
Q

What happens when there’s decreased SA automaticity?

A

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.

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10
Q

What’s an escape beat?

A

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

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11
Q

What’s an escape rhythm?

A

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

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12
Q

Increased PNS yields what?

A

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

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13
Q

What’s an ectopic beat?

A

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

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14
Q

What’s ectopic rhythm?

A

It’s a sequence of ectopic beats.

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15
Q

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

A

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

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16
Q

What’s abnormal automaticity?

A

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

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17
Q

What is triggered activity?

A

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

18
Q

What is a conduction block?

A

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

19
Q

What is a functional block?

A

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

20
Q

What’s the fixed block?

A

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

21
Q

What is Wolf Parkinson White syndrome?

A

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.

22
Q

What happens when you have sinus bradycardia?

A

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.

23
Q

What’s sick sinus syndrome?

A

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

24
Q

What’s junctional escape rhythm?

A

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

25
Q

What’s ventricular escape rhythm?

A

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

26
Q

What’s first degree AV block?

A

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

27
Q

What’s second degree AV block?

A

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

28
Q

What’s third degree AV degree block?

A

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

29
Q

What are the supraventricular tachyarrhythmias?

A

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

30
Q

What’s sinus tachycardia?

A

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

31
Q

What’s atrial premature beats?

A

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

32
Q

What’s atrial flutter?

A

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

33
Q

What’s atrial fibrillation?

A

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.

34
Q

What are ventricular arrhythmias?

A

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

35
Q

What’s Ventricular Premature Beats?

A

Occurs when an ectopic ventricular focus fires an AP.

36
Q

What’s sustained VT?

A

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

37
Q

What’s nonsustained VT?

A

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.

38
Q

What’s ventricular fibrillation?

A

Disordered, rapid stimulation of the ventricles without coordinated contraction.

39
Q

What are the four signs of infarction?

A

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

40
Q

What’s is ST elevation specifically?

A

Myocardial infarction

41
Q

What is ST depression specifically?

A

myocardial ischemia.