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Ventricular tachycardia, ventricular flutter, and ventricular fibrillation differential diagnosis
1. Differential Diagnosis and Treatment of Ventricular
Tachycardia, Ventricular Flutter, and Ventricular
Fibrillation
2. Overview
►Ventricular tachycardia usually precedes ventricular flutter and ventricular fibrillation
►Ventricular tachycardia may impair cardiac output with consequent hypotension, collapse, and acute
cardiac failure. This is due to extreme heart rates and lack of coordinated atrial contraction
►Decreased cardiac output may result in decreased myocardial perfusion with degeneration to VF
►VT is a common health problem encountered in clinical practice
►VT is responsible for most of sudden cardiac deaths in US, at an estimated rate of approximately
300,000 deaths per year.
►ECG is used to differentiate types of ventricular tachycardia
►Risk factors for ventricular tachycardia are hypertension, previous myocardial infarction, chronic
obstructive pulmonary disease (COPD)
►The presence of pre-existing poor ventricular function is strongly associated with cardiovascular
compromise.
►The most common cause of VT is ischemic heart disease
►Monomorphic VT is the most common form
3. Ventricular Tachycardia
Occurs due to rapid discharge of an ectopic ventricular pacemaking focus
Wide complex rhythm QRS >0.12s
Series of three or more consecutive beats on ECG at a rate of 100 BPM or greater
Caused by significant heart disease: coronary artery disease, previous myocardial
infarction, cardiomyopathy, etc.
Could be life threatening
Can be monomorphic or polymorphic
Also can be classified as sustained or non-sustained VT. Sustained VT is any ventricular
tachycardia that lasts for more than 30 seconds or is symptomatic, seen in patients with
MI or chronic coronary artery disease. Non-sustained VT lasts for less than 30 seconds
and is asymptomatic. Is seen in ischemic or non-ischemic heart diseases, brugada
syndrome, metabolic problems including drug toxicity, and electrolyte imbalance
4. Classification and Causes of Ventricular Tachycardia
Monomorphic Ventricular
Tachycardia (QRS complex
remains identical from beat-beat)
• Chronic coronary artery disease
• Idiopathic VT
• Right ventricular dysplasia
• Bundle branch reentry tachycardia
• Ventricular flutter
• Ventricular fibrillation
Polymorphic Ventricular
Tachycardia (QRS complex
changes from beat-beat)
• Long QT interval (torsades de
pointes) – Congenital or acquired
(ischemic, drugs-induced,
hypokalemia)
• Normal QT interval – Brugada
syndrome, CPVT, acute ischemia or
infarction)
5. Clinical Presentation
• Hemodynamically stable: asymptomatic or minimal symptoms e.g. palpitations.
• Hemodynamically unstable —hypotension, tachypnea, chest pain, light headedness,
decreased consciousness, pallor, diaphoresis, syncope, sudden cardiac arrest or sudden
cardiac death
ECG features
Very broad complexes (>160ms)
AV dissociation: P wave and QRS complex at different rates
Capture beats
Fusion beats
Absence of typical RBBB or LBBB morphology.
Positive or negative concordance: absence of RS complex in all precordial leads
6. Monomorphic VT
• Regular rhythm.
• Originates from a single focus within the ventricles.
• Produces uniform QRS complexes within each lead — each QRS is identical
(except for fusion/capture beats).
Causes
• Ischemic heart disease
• Dilated cardiomyopathy
• Hypertrophic cardiomyopathy
• Chaga’s disease
7.
8. Treatment
Non-sustained ventricular tachycardia
No therapy is required in asymptomatic patients without underlying cardiac
disease
Symptomatic patients: beta blockers, if episodes continue -> calcium channel
blockers e.g. verapamil or diltiazem can be used
Sustained monomorphic ventricular tachycardia
• Hemodynamically unstable:
immediate cardioversion with a 100-200J biphasic shock, and correction of
metabolic disturbances
In case of MI, it should be treated with lidocaine (2-3mg/kg)
• Hemodynamically stable:
Anti-arrhythmics: IV amiodarone or procainamide
9. Treatment, Continued….
First line therapy for ischemic heart disease and VT is a beta blocker which highly
reduces mortality (sudden cardiac death)
In case of recurrent VT despite beta-blockers therapy, amiodarone, or sotalol can be
used.
An implantable cardiac defibrillator (ICD) is very effective in preventing sudden
cardiac death and should be placed in those that survive sudden cardiac arrest, or
experience hemodynamically unstable or stable sustained ventricular tachycardia
Cardiac ablation through catheters is recommended for patients with a history of
myocardial infarction who continue to have sustained symptomatic VT and have
failed or are intolerant of amiodarone or other antiarrhythmic agents.
10. Polymorphic VT
• Multiple ventricular foci with the resultant QRS complexes varying in amplitude,
axis and duration.
• The commonest cause of PVT is myocardial ischemia.
• Biphasic VT: a form of polymorphic ventricular tachycardia with a QRS complex
that alternates from beat to beat. Associated with digoxin intoxication and long
QT syndrome.
• Torsades de pointes is a specific form of polymorphic ventricular tachycardia
with QT prolongation; it has a characteristic morphology in which the QRS
complexes twist around the isoelectric line (change axis).
Causes of Torsades de Pointes
• Congenital long QT syndrome
• Acquired long QT syndrome: secondary to multiple drugs’ effects, hypokalemia,
and other medical conditions.
11.
12. Treatment of Tdp
Electrocardioversion is the first treatment for TdP. Additional treatments are:
• Withdrawal of any offending drugs and correction of electrolyte abnormalities
(potassium repletion up to 4.5 to 5 mmol/liter).
• Intravenous magnesium sulfate for patients with QT prolongation and few
episodes of TdP.
• Beta blockers combined with cardiac pacing as acute therapy for patients with
TdP and sinus bradycardia.
• Isoproterenol as temporary treatment in patients with recurrent pause-
dependent TdP who do not have congenital long QT syndrome.
13. Diagnosis of VT
• In a patient who is hemodynamically unstable or unconscious, the diagnosis
of VT is made from the physical findings and ECG rhythm strip only.
• ECG findings:
Absence of an RS complex in all precordial leads
RS interval >100 ms
AV dissociation or dissociation of P wave from QRS complex
Capture beats: sinus conducted impulse during ectopic ventricular beat
Fusion beats: occur when a sinus and ventricular beat coincide producing a
hybrid complex
14.
15.
16.
17. Ventricular Flutter
Extreme form and a very rapid ventricular tachycardia (occurs at a rate of around 300
BPM), mostly caused by a reentry circuit.
The QRS complexes are regular and usually monomorphic.
The ventricles depolarize in a circular pattern, which prevents good function, this
results in a minimal cardiac output. Often deteriorates into ventricular fibrillation.
Associated with rapid and profound hemodynamic compromise and is fatal within
minutes without intervention
ECG features:
Continuous sine wave
No identifiable P waves, QRS complexes, or T waves
Rate >300 beats / min
Treatment: DC-defibrillation (200-360J) is the only treatment
18.
19.
20. Ventricular Fibrillation
Represents uncoordinated very rapid, irregular, and ineffective ventricular
contractions caused by many chaotic electric impulses. Terminal arrhythmia and
requires rapid initiation of management.
Mechanism
In the presence of ischemic heart disease VF may be preceded by:
Premature ventricular contractions (PVCs)
ST changes
R on T phenomenon or ventricular extrasystoles
Pauses
QT prolongation
Ventricular Tachycardia
Ventricular Flutter
Supraventricular arrhythmias
21. Causes of Ventricular Fibrillation
Ischemic heart disease or coronary artery disease
MI
Cardiomyopathy (dilated, hypertrophic, restrictive)
Aortic stenosis
Aortic dissection
Myocarditis
Cardiac tamponade
Blunt trauma (commotio cordis)
Respiratory disorders
Electrolyte disturbances: hypokalemia, hyperkalemia, acid base disturbances
Drug-induced QT prolongation with torsades de pointes
Environmental: electric shocks, hypothermia, drowning, sepsis
Seizures, CVA
22. ECG Findings:
Chaotic irregular deflections of varying amplitude
No identifiable P waves, QRS complexes, or T waves
Heart rate 150 – 500 BPM
Amplitude decreases with duration, from coarse VF to fine VF which can resemble asystole.
Clinical Significance
• Ventricular fibrillation (VF) is the the most important shockable cardiac arrest rhythm.
• This rapid and irregular electrical activity renders the ventricles unable to contract in a
synchronized manner, resulting in immediate loss of cardiac output.
• VF gives rise to a mechanical standstill of the heart, because the heart is not able to
pump normally anymore. It’s fatal in all cases if treatment isn’t initiated immediately.
• Defibrillation is the only treatment for VF.