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Hyms year 2 > Block 13 Week 4 > Flashcards

Block 13 Week 4 Flashcards

1
Q

Rhythm of the heart

A
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2
Q

Things to know on an ECG

A
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3
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A
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4
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A
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5
Q

Sinus Bradycardia

A
  • We have normal QRS complex and P-waves and they are regular. We just have less QRS complexes

-

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6
Q

Cause of Bradycardia

A

Physiological: common in younger populations, athletes and during sleep.

Cardiac:

-Sick sinus syndrome: disorder of the sinoatrial node.

-Heart block: disorder of the atrioventricular node.

-Post-myocardial infarction: post-inferior myocardial infarction. The right coronary artery supplies the SAN (pacemaker of the heart).

-Aortic valve disease: the right coronary artery origin is disrupted just above the aortic valve.

Non-cardiac:

-Vasovagal (temporary fall in blood pressure)

-Endocrinological: hypothyroidism.

-Hypothermia

-Electrolyte abnormalities

-Cushing’s triad of raised ICP: bradycardia, irregular breathing and hypertension.

-Medications: beta-blockers, calcium channel blockers, digoxin etc.

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7
Q

Symptoms of Bradycardia

A

-Lightheadedness

-Syncope

-Fatigue

-Shortness of breath

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8
Q

Investigating Bradycardia

A

Bedside:
ECG: help indicate underlying cause for the bradyarrhythmia. E.g. sick sinus syndrome with severe bradycardia and long pauses vs. heart block with prolonged PR interval.

Bloods:
If considering a non-cardiac cause of the bradyarrhythmia (e.g. heart block).

Imaging:
TTE: if considering causes such as post-MI (looking for regional wall motion abnormalities) or aortic valve disease.

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9
Q

Management of Bradycardia

A

1st line = 500 micrograms atropine IV

Atropine blocks the vagal nerve which increases firing rate of the SAN.

2nd line = if atropine not working can consider transcutaenous pacing or isoprenaline or adrenaline.

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10
Q

Bradycardia Treatment

A
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11
Q

What is the most common cause of Bradycardia?

A

The most common cause of pathological bradycardia is sick sinus syndrome and is estimated to have an incidence of 1 in 600 peopel over the age of 65.

It affects both sexes equally.

  • Sick sinus syndrome encompasses many conditions that cause dysfunction in the sinoatrial node. It is often caused by idiopathic degenerative fibrosis of the sinoatrial node.
  • It can result in sinus bradycardia, sinus arrhythmias and prolonged pauses.
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12
Q

Asystole

A

Asystole - is when your hearts electrical system fails entirely which causes your heart to stop pumping

  • This is also known as ‘flat lining’ because of how your hearts electrical activity appears as a flat line
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13
Q

In which conditions is there a risk of asystole?

A

-Mobitz type 2

-Third-degree heart block (complete heart block)

-Previous asystole

-Ventricular pauses longer than 3 seconds

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14
Q

Management of unstable patients and those at risk of asystole involves:

A

-Intravenous atropine
(first line)

  • Inotropes (e.g., isoprenaline or adrenaline)

-Temporary cardiac pacing

-Permanent implantable pacemaker, when available

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15
Q

Temporary Cardiac Pacing

A

Options for temporary cardiac pacing are:

-Transcutaneous pacing, using pads on the patient’s chest

-Transvenous pacing, using a catheter, fed through the venous system to stimulate the heart directly

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16
Q

Atropine

A

Atropine is an antimuscarinic medication and works by inhibiting the parasympathetic nervous system.

Inhibiting the parasympathetic nervous system leads to side effects of pupil dilation, dry mouth, urinary retention and constipation.

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17
Q

First Degree Heart Block

A

First-degree heart block occurs where there is delayed conduction through the atrioventricular node. Despite this, every atrial impulse leads to a ventricular contraction, meaning every P wave is followed by a QRS complex.

On an ECG, first-degree heart block presents as a PR interval greater than 0.2 seconds (5 small or 1 big square)

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18
Q

Second Degree Heart Block

A

Second-degree heart block is where some atrial impulses do not make it through the atrioventricular node to the ventricles. There are instances where P waves are not followed by QRS complexes.

There are two types of second-degree heart block:

  • Mobitz type 1 (Wenckebach phenomenon)
  • Mobitz type 2
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19
Q

Mobitz Type 1 ( Wenckebach phenomenon)

A

Mobitz type 1 (Wenckebach phenomenon) is where the conduction through the atrioventricular node takes progressively longer until it finally fails, after which it resets, and the cycle restarts.

On an ECG, there is an increasing PR interval until a P wave is not followed by a QRS complex. The PR interval then returns to normal, and the cycle repeats itself.

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20
Q

Mobitz type 2

A

Mobitz type 2 is where there is intermittent failure of conduction through the atrioventricular node, with an absence of QRS complexes following P waves.

There is usually a set ratio of P waves to QRS complexes, for example, three P waves for each QRS complex (3:1 block). The PR interval remains normal. There is a risk of asystole with Mobitz type 2.

A 2:1 block is where there are two P waves for each QRS complex. Every other P wave does not stimulate a QRS complex. It can be difficult to tell whether this is caused by Mobitz type 1 or Mobitz type 2.

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21
Q

Third degree heart block

A

Third-degree heart block is also called complete heart block. There is no observable relationship between the P waves and QRS complexes.

There is a significant risk of asystole with third-degree heart block.

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22
Q

Sinus Arrest

A
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23
Q

Brady -tachy syndrome

A

Intermittent episodes of slow and fast heart rate from the SA node or atria

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24
Q

Bundle Branch Block

A
  • A bundle branch block (BBB) refers to when electrical impulses to the ventricles are slower than normal, leading to a widened QRS complex >120ms.
  • It can be classified as left bundle branch block (LBBB) or right bundle branch block (RBBB)
  • An incomplete BBB refers to when there is a partial delay in electrical conduction in the ventricles and the QRS complex is between 110 to 120ms.
25
Q

Which bundle branch block is more common?

A

RBBB is more common than LBBB.

  • LBBB is a rarer finding on ECG
26
Q

Interventricular Conduction Delay

A

LBBB is recognised by the “WILLAM” pattern in V1 and V6, whilst RBBB is identified by the “MARROW” pattern.

27
Q

Left bundle branch block

A

-In both, the QRS complex has a duration of >120ms.

-In V1 if the QRS complex has the appearance of a W (the rS’ pattern) and in V6 the QRS has the appearance of M (due to a notched R wave) this is a left bundle branch block. WiLLaM.

28
Q

Right bundle branch block

A

In V1 if there is an appearance of an M (due to the rSr’pattern) and in V6 the QRS complex usually looks normal (N). This is a right bundle branch block. MaRRoW.

29
Q

Causes of LBB

A

-Aortic stenosis

-Ischaemic heart disease

-Hyperkalaemia

-Digoxin toxicity

-Myocardial infarction - new LBBB can indicate STEMI.

30
Q

Causes of RBBB

A

-Right ventricular hypertrophy

-Pulmonary embolism

-Ischaemic heart disease

-Congenital heart disease (ASD)

-Normal variant

31
Q

Tachycardia

A

SVT= supraventricular tachycardia

32
Q

Narrow Complex Tachycardia

A

Narrow complex tachycardia refers to a fast heart rate with a QRS complex duration of less than 0.12 seconds. On a normal 25 mm/sec ECG, 0.12 seconds equals 3 small squares.

Therefore, the QRS complex will fit within 3 small squares in narrow complex tachycardia.

33
Q

What can tachycardia cause?

A
  • Heart Failure
  • Stroke

Rate is controlled suing beta blockers

  • Rhythm which is the flutter is controlled using Cardioversion
34
Q

What are the 4 main diffrentials of a narrow complex tachycardia

A

There are four main differentials of a narrow complex tachycardia:

-Sinus tachycardia (treatment focuses on the underlying cause)

-Supraventricular tachycardia (treated with vagal manoeuvres and adenosine)

-Atrial fibrillation (treated with rate control or rhythm control)

-Atrial flutter (treated with rate control or rhythm control, similar to atrial fibrillation)

35
Q

Supraventricular Tachycardia

A
36
Q

Atrial flutter

A

Atrial flutter is a common supraventricular tachycardia (SVT). It is characterised by an abnormal cardiac rhythm with an atrial rate of 300 beats/min and a ventricular rate that can be fixed or variable that causes symptoms.

Atrial flutter is caused by an aberrant re-entrant circuit within the right atrium which cycles at 300bpm.

This circuit activates the AV node but because this node has a relatively long refractory period it is not able to conduct impulses down the His-Purkinje system at such a fast rate.

Instead there is a degree of block meaning that only 2:1, 3:1, 4:1 or rarely 5:1 atrial impulses are conducted to the ventricle.

37
Q

Atrial Flutter causes

A
38
Q

Atrial Flutter

A

Normally the electrical signal passes through the atria once, stimulating a contraction, then disappears through the atrioventricular node into the ventricles. Atrial flutter is caused by a re-entrant rhythm in either atrium. The electrical signal re-circulates in a self-perpetuating loop due to an extra electrical pathway in the atria. The signal goes round and round the atrium without interruption. The atrial rate is usually around 300 beats per minute.

The signal does not usually enter the ventricles on every lap due to the long refractory period of the atrioventricular node. This often results in two atrial contractions for every one ventricular contraction (2:1 conduction), giving a ventricular rate of 150 beats per minute. There may be 3:1, 4:1 or variable conduction ratios.

Atrial flutter gives a sawtooth appearance on the ECG, with repeated P wave occurring at around 300 per minute, with a narrow complex tachycardia.

Treatment is similar to atrial fibrillation, including anticoagulation based on the CHA2DS2-VASc score. Radiofrequency ablation of the re-entrant rhythm can be a permanent solution.

39
Q

Atrial Flutter ECG appearance

A

-Saw-tooth baseline with repetition at 300bpm (these are atrial flutter waves)

-Narrow QRS complexes

-Ventricular rate which depends on the level of AV block:

150bpm if 2:1
100bpm if 3:1
75bpm if 4:1
60bpm if 5:1

40
Q

Hemodynamically unstable

A

Signs of haemodynamic instability:

-Shock: suggests end-organ hypoperfusion.

-Syncope: cerebral hypoperfusion.

-Chest pain: myocardial ischaemia.

-Pulmonary oedema: evidence of heart failure.

41
Q

Atrial Flutter management

A

If hemodynamically unstable:
- 1st line = direct current synchronised cardioversion +/- amiodarone.

Next we want to control rate and rhythm:

  • 1st line = beta-blocker (bisoprolol) OR calcium channel blocker (diltiazem, verapamil)
  • 2nd line = if rate control fails to control flutter than consider cardioversion.

-3rd line = recurrent or refractory flutter managed with ablation of arrhythmogenic foci at cavotricuspid isthmus. Success rate high at 90%.

42
Q

Atrial Flutter symptoms

A

Asymptomatic
Palpitations
Lightheadedness
Syncope
Chest pain

43
Q

Atrial Fibrillation

A
  • Atrial Fibrillation is the most common type of arrhythmia

Atrial fibrillation (AF) is characterised by irregular, uncoordinated atrial contraction usually at a rate of 300-600 beats per minute.

Delay at the AVN means that only some of the atrial impulses are conducted to the ventricles, resulting in an irregular ventricular response.

44
Q

Atrial Fibrillation

A

Fibrillation describes when the muscle fibers are all contracting at different times, so the end result is a quivering, or twitching movement.

Normally, an electrical signal is sent out from the sinus node in the right atrium. The signal then propagates out through both atria super fast, which allows them to depolarize at about the same time, so that you end up with a nice, coordinated contraction of the atria. That signal then moves down to the ventricles and causes them to contract shortly after.

With Atrial fibrillation, or A-fib or AF, signals move around the atria in a completely disorganized way that tends to override the sinus node. Instead of one big contraction, you get all these mini contractions that make it look like the atria are just quivering.

45
Q

Atrial Fibrillation ECG

A

all these mini contractions that make it look like the atria are just quivering.

On an electrocardiogram, or ECG, normally the “P wave” corresponds to the atrial contraction. The “QRS complex,” which is the ventricular contraction, follows shortly after. During AF, all these small areas contract at different times so that you end up with an electrocardiogram that looks like scribbles, where each little peak corresponds to one spot in the atria twitching. Sometimes, a signal from one of these areas makes it down to the ventricles and cause ventricular contraction; these QRS complexes are interspersed at irregular intervals though, and usually at fairly high rates between 100 and 175 beats per minute.

46
Q

Pathophysiology of AF

A

The exact pathophysiology of AF is unclear, but factors that cause atrial dilatation through inflammation and fibrosis leads to disorganised electrical impulses (which originate near the pulmonary veins) that overwhelm the SAN. These disorganised electrical impulses are usually at a rate of 300-600 beats per minute and are intermittently conducted through the AVN leading to irregular activation of the ventricles.

47
Q

Classification

A

-Acute: lasts <48 hours

-Paroxysmal: lasts <7 days and is intermittent

-Persistent: lasts >7 days but is amenable to cardioversion

-Permanent: lasts >7 days and is not amenable to cardioversion

-Atrial fibrillation can also be classified as to whether it is ‘fast’ or ‘slow’. Fast AF refers to AF that is at a rate of =>100bpm. Slow AF refers to AF that is at a rate of <=60bpm.

48
Q

Causes

A

Symptoms

49
Q

Atrial Fibrillation Appearance

A

An ECG showing an irregularly irregular heart rate and absent p waves, these are characteristic signs of atrial fibrillation.

50
Q

Atrial Fibrillation management

A

same as atrial flutter

51
Q

Treatment of Narrow Complex Tachycardia

A

-Patients with life-threatening features, such as loss of consciousness (syncope), heart muscle ischaemia (e.g., chest pain), shock or severe heart failure, are treated with synchronised DC cardioversion under sedation or general anaesthesia.

-Intravenous amiodarone is added if initial DC shocks are unsuccessful.

52
Q

Broad Complex Tachycardia

A

Broad complex tachycardia refers to a fast heart rate with a QRS complex duration of more than 0.12 seconds or 3 small squares on an ECG.

53
Q

Categories of Broad Complex Tacycardia

A

The resuscitation guidelines break down broad complex tachycardia into:

-Ventricular tachycardia or unclear cause (treated with IV amiodarone)

-Polymorphic ventricular tachycardia, such as torsades de pointes (treated with IV magnesium)

-Atrial fibrillation with bundle branch block (treated as AF)

-Supraventricular tachycardia with bundle branch block (treated as SVT)

54
Q

Treatment of Broad Complex tachycardia

A

Patients with life-threatening features, such as loss of consciousness (syncope), heart muscle ischaemia (e.g., chest pain), shock or severe heart failure, are treated with synchronised DC cardioversion under sedation or general anaesthesia. Intravenous amiodarone is added if initial DC shocks are unsuccessful.

55
Q

Ventricular Tachycardia

A
56
Q

Polymorphic VT: Torsades de Pointes

A
57
Q

Tachycardia Treatment

A
58
Q
A

Hyms year 2 (36 decks)

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