Ventricular Arrhythmias Flashcards
What are the 3 main types of ventricular arrhythmias?
NSVT - Non-sustained ventricular tachycardia
VT - (sustained) ventricular tachycardia
VF - Ventricular fibrillation
Define a Non-sustained VT
Define VT
What are the characteristic features on ECG
NSVT - 3+ consecutive broad complexes with a HR>100/120, and lasting <30s.
VT - 3+ consecutive complexes, HR>100/120, lasting >30s
Broad QRS complexes (>120ms) with AV dissociation (P and QRS are dissociated)
What are the reversible causes of ventricular arrhythmias?
6Hs and 6Ts
Hs: Hypothermia, hypoxia, hypovolemia, hypoglycemia, hypomagnesia, hyper/hypokalameia
Ts: Thrombosis (MI,PE), Trauma, Tamponade, Tension pneumothorax, long qT medications (Class Ia, III, macrolides, methadone, antidepressants and antipsychotics), Toxins
What are the main RFs/causes of Ventricular Arrhythmias (all similar)
Include the reversible causes
Cardiac:
Aortic dissection
Myocarditis
Ischaemia (MI) - Thrombosis
Cardiac Tamponade
Resp: PE (Thrombosis), (Tension) pneumothorax
Neuro: Stroke, Seizure
Electrolyte: Hypomagnesia, Hypo/Hyperkalaemia, Hypoglycaemia (i know its not an electrolyte)
Environmental: Trauma, Hypothermia, Hypoxia (drowning), Electric shock
Drugs: Long QT drugs (Class Ia, III, macrolides, methadone, antidepressants and antipsychotics)
Other Hs: Hypovolaemia, hypoglycaemia
What is the pathophysiology of NSVT?
In healthy individuals - Reactivation of Na and Ca channels
In patients with significant previous cardiac disease - Damaged myocardium leads to cardiac remodelling leading to re-entrant impulses causing arrhythmia (just like in A.fib)
What is the pathophysiology of VT
VT arises from an impulse either from the ventricular myocardium and/or anywhere distal to the bundle of his (as opposed to SVT), resulting in re-entry pathways
Long QT syndrome will cause what morphology of Ventricular tachycardia?
Long QT syndrome causes Toursades de Points which is a Polymorphic VT
It literally changes from positive deflection to -ve deflection => polymorphic
Ventricular tachycardia is unpredictable and a life threatening event => it is important to make distinctions in:
Duration:
Morphology:
Associated symptoms:
Associated Cardiac disease:
For each of the above, make these distinctions explaining how.
Duration: Sustained (>30s) vs Not sustained (<30s)
Morphology: Monomorphic vs Polymorphic (post-MI or Toursades de Points) - are all the QRS the same shape?
Associated symptoms: None, Haemodynamic instability, collapse.
Associated Cardiac disease: Non-malignant vs Malignant (CHD, MI, cardiomyopathy)
What is the significance if making the distinction if a VT is malignant or not?
Malignant (=associated cardiac disease such as CHD, MI, cardiomyopathy) increases the risk of cardiac arrest and sudden cardiac death
Ddx for any arrhythmia (asymptomatic)
All the other arrhythmias of the same type b/w tachy and brady
=> SVT: A.fib, Flutter, AVNRT, AVRT, Atrial tachycardia, MAT (Multifocal AT), SANRT (SA nodal re-entrant tachy)
VT: NSVT, VT, VF
+ Electrical artifacts
What are some examples of electrical artifacts
Tremor from parkinsons, MS, SABAs, hyperthyroidism, hepatic encephalopathy
patient movement
electrode movement
Dont take this question too seriously
What are signs and symptoms of ventricular arrhythmias
Symptoms: Palpitations, syncope/pre-syncope, dyspnoea, chest pain
Signs:
Vitals: Rapid Irregular pulse/absent pulse, BP normal/low/absent
GI: Diaphoretic, LOC
CI: !! Cannon A waves
Auscultation:Variability in rhythm and intensity of heart sounds
What is the typical presentation of Ventricular fibrillation?
Collapse with no CO => no pulse, no BP
When are Ventricular fibrillations most likely to occur?
48-72 hours after the onset of symptoms presumably due to ischaemia or lack of perfusion to the infarcted vessel (e.g. post-MI)
What are Cannon A waves?
Irregular JVP pulsations due to contraction of the right atrium against a closed tricuspid valve
What investigations will you perform for ventricular arrhythmias
As for any arrhythmia: except ECG
Bedside:
ECG/!Holter monitor: looking for patterns consistent with NSVT, VT, or VF (specific questions will come) + screen for previous MI, BBB, or LV hypertrophy
Urine dipstick (sepsis)
Urinalysis (evidence of CKD to guide management between DOAC and Warfarin) + Toxicology (sympathetomimetics)
Bloods:
FBC - Anaemia, infection, low platelets if DIC, infection, sepsis)
CRP - raised in infl. + inf.
U&E - Hypomagnesia + hyper/hypokalaemia + medications
TFTs - hyperthyroidism
Troponin + CKMB (ischaemia as a cause or result of arrhythmia)
BNP - HF in severe arrhythmia
HbA1c and Lipid profile (RFs)
Imaging:
CXR - sx of HF (ABCDE)
ECHO - TTE - atrial/ventricular size (LA enlargement/LV hypertrophy), RV systolic pressure, valvular involvement, pericardial disease - TOE - LA (appendage) thrombus, Rule out vegetations in IE
Procedure: Exercise stress test - helps identify ischaemia (not rly done so not required for 5/5)
What is the typical length of QRS?
How about in VT?
What are the 3 types of QRS complexes seen on a VT ECG along with their relative QRS?
Normal QRS is 80-100 (or 60-120)
In VT it is widened => >120 in general
3 beats:
Normal VT beats»_space;120
Fusion beat >120
Capture beat 80-120 or whatever variation of normal you choose
What would an ECG of Ventricular tachycardia show?
Go through all the features
NSVT and VT are the same cuz the only difference is how long they last
Definition: 3 consecutive complexes, HR>100/120, for < or > 30s
Features:
1) Tachycardia >100/120
2) AV dissociation
3) Wide QRS >120 (in general)
4) 3 beats: VT, Fusion, Capture beat