Arrhythmias – Supraventricular Tachycardia (SVT) – Atrial Fibrillation Flashcards
Define supraventricular tachycardia (SVT) arrhythmia
An abnormality of the heart’s rate or rhythm, originating in the atria
What is Bradycardia/Bradyarrhythmia defined as?
< 60bpm
What is Sinus Bradycardia?
Caused by Sinus pauses, Sick Sinus Syndrome, Ischaemia and Infarction
What is Tachycardia/Tachyarrhythmia defined as?
> 100bpm
What are Supraventricular Tachyarrhythmias?
Occurring in the atria/above the ventricles
What are the types of SVT?
Atrial Fibrillation, Atrial Flutter, AVRT and AVNRT
What are types of AFib?
- Paroxysmal AF
- Persistent AF
- Longstanding persistent AF
- Permanent AF
What is paroxysmal AF?
Intermittent arrhythmias lasting minutes to days
What is persistent AF?
Lasts longer than 7 days, or less when treated
What is longstanding persistent AF?
Continuous AFib for a year or longer
What is permanent AF?
Severe AFib present all the time, no attempts to restore normal heart rhythm made
What is the pathophysiology of AFib?
- Characterised by abnormal electrical activity within the atria, causing them to fibrillate and not pump blood effectively
- There can be pooling of blood which can lead to thromboembolic events
- Most common cardiac rhythm disorder
What is AFib most caused by?
cardiac remodelling (changes in the structure of the heart) in response to disease/damage
What does AFib often show on presentation?
asymptomatic
What shows on an ECG for AFib?
irregularly irregular pulse without p waves
What are symptoms for AFib?
Palpitations
Chest Pain
Shortness of Breath/Dyspnoea
Dizziness/syncope
What are signs of AFib?
Irregularly irregular pulse
Hypotension
Evidence of heart failure
What are risk factors for AFib?
Advancing age
Male sex
Family history
Hypertension
Heart conditions
Alcohol consumption
Smoking
Thyroid disorders
Chronic kidney disease (CKD)
What are complications of AFib?
Ischaemic Stroke
Heart failure
Cardiogenic Shock
What are investigations for AFib?
- ECG
- Bloods
- CXR
- Transoesophageal Echocardiogram
What is seen on an ECG for AFib?
- “Irregularly Irregular” rate and no distinguishable p waves
- Fibrillatory waves may be present or absent
What is seen in bloods results for AFib?
To determine causes:
- FBC for infection and electrolyte imbalances
- TFTs for hyperthyroidism
- Cardiac biomarkers and BNP for cardiac disease
Why is a CXR done?
Check for abnormality
Why is a Transoesophageal Echocardiogram done?
To assess for cardioversion
How long is acute AFib presentation?
<48hrs after symptoms
What type of patients are usually seen for acute AFib?
Patients are usually younger and present with severe symptoms
What are acute AFib symptoms?
Rapid pulse (>150bpm)
Low BP (Systolic BP < 90mmHh)
Loss of consciousness (Syncope)
Chest Pain
SOB (Dyspnoea)
What are the aims for treating acute AFib?
- Treat underlying conditions which may cause AF (e.g. MI, Pneumonia)
- Control Ventricular rate (Using either 1st or 2nd line agents)
What 2 treatments would you consider for acute AFib?
- anticoagulants
- DC or drug cardioversion
Describe anticoagulant treatment for acute AFib
Heparin whilst the patient is assessed and then oral anticoagulation after AFib is confirmed
Describe DC or drug cardioversion treatment for acute AFib
- Use DC cardioversion in an acute setting
- performed in ITU setting with sedation
- shocked at 200J initially, if unsuccessful, try 2 further attempts at 360J
- Thrombi are a contraindication for cardioversion
What are the aims for treating chronic AFib?
- Identify and treat reversible causes
- Conduct echo to rule out structural heart disease
- Control Ventricular rate or rhythm
What are the 1st line rate control options for treating chronic AFib?
1st Line
- Beta Blocker OR Ca2+ Blocker (Using both is contraindicated; causes heart block)
- BB is generally preferred (Atenolol, Bisoprolol, Carvedilol etc.)
What are the 2nd line rate control options for treating chronic AFib?
2nd Line
– Same as 1st line but add Digoxin or Amiodarone
- Digoxin cannot be used as the sole treatment for AF
What are the rhythm control options for treating chronic AFib?
- Flecainide
- Amiodarone
- Electrical Cardioversion
- Catheter Ablation
What is flecainide contraindicated in?
Contraindicated in LV dysfunction, LV hypertrophy
What can amiodarone cause?
Can cause thyrotoxicosis; Excess T3 or 4
Which type of patients is catheter ablation usually used in?
In younger patients with failed rhythm control using other options
What is used to assess need for anticoagulation?
CHA2DS2-VASc
What is used to assess bleeding risk?
ORBIT
What does a CHA2DS2-VASc score of 0 mean?
Risk is low, No AC therapy needed
What does a CHA2DS2-VASc score of 1 mean?
Risk is low-moderate, AC therapy considered
What does a CHA2DS2-VASc score of 2+ mean?
Risk is moderate or high, AC therapy recommended
What does an ORBIT score of 0-2 mean?
Risk is low, 2.4 bleeds per 100 patient-years (unit of measurement for risk)
What does an ORBIT score of 3 mean?
Risk is medium, 4.7 bleeds per 100 patient-years
What does an ORBIT score of 4-7 mean?
Risk is high, 8.1 bleeds per 100 patient-years
What does CHA2DS2-VASc stand for?
C- Congestive HF +1
H- Hypertension +1
A2- Age 75+ +2
D- DM+1
S2- Previous stroke, TIA or thromboembolism +2
V- Vascular disease +1
A- Age 65-74 +1
Sc- Sex category (female) +1
What does ORBIT stand for?
O - Older (75+) +1
R- Reduced Hb +2
B- Bleeding history +2
I- Insufficient kidney function +1
T- Treatment with antiplatelet agent +1
What are 2 types of DOACs (Direct Oral Anticoagulants)?
Factor Xa inhibitors
Thrombin inhibitors
What are examples of factor Xa inhibitors?
rivaroxaban, apixaban
What is an example of thrombin inhibitors?
dabigatran
What is preferred DOACs or warfarin?
DOACs
Why are DOACs preferred over warfarin?
- DOACs don’t require monitoring of INR (International normalised ratio; used to measure length of time to clot) unlike warfarin (Need to maintain a level of INR in an individual on warfarin)
- DOACs have less drug interactions
- DOACs have standardised dosing
What are disadvantages of DOACs?
- DOACs are less easily reversible; hard to stop the effects of DOACs if patient is bleeding
- DOACs not recommended for use when structural heart disease present
Summarise the treatment for paroxysmal AFib
- 1st line – Sotalol/Bisoprolol (Beta Blockers)
In youth, use Flecainide/Verapamil, avoid in elderly (negatively ionotropic) - 2nd line – Amiodarone
- 3rd line – Digoxin; useful in LV dysfunction as it is positively ionotropic
- Consider Anticoagulants
- Consider DC Cardioversion + Amiodarone