STEPUP Cardiovascular System: Tachyarrhythmias - Ventricular Tachycardia Flashcards
What is ventricular tachycardia? Is AV dissociation present and what is it? Where does ventricular tachycardia originate?
1) Defined as rapid and repetitive firing of three or more PVCs in a row, at a rate of between 100 and 250 bpm
2) AV dissociation is present, that is, sinus P waves continue with the cycle, unaffected by the tachycardia
3) Originates below the bundle of His
What are causes of ventricular tachycardia (VT)?
1) CAD with prior MI is the most common cause
2) Active ischemia, hypotension
3) Cardiomyopathies
4) Congenital defects
5) Prolonged QT syndrome
6) Drug toxicity
How long does sustained VT last for? What is it associated with? Is it life-threatening? What can it progress to if untreated?
Sustained VT (persists in the absence of intervention)
1) Lasts longer than 30 seconds and is almost always symptomatic
2) Often associated with marked hemodynamic compromise (i.e., hypotension) and/or development of myocardial ischemia
3) A life-threatening arrhythmia
4) Can progress to VFib if untreated
How long does nonsustained VT last for? Is it symptomatic? When is it an independent risk factor for sudden death?
1) Brief, self-limited runs of VT
2) Usually asymptomatic
3) When CAD and LV dysfunction are present, it is an independent risk factor for sudden death. Therefore, patients with nonsustained VT should be thoroughly evaluated for underlying heart disease and LV dysfunction
What does the prognosis of VT depend on? After what does VT have poor prognosis, especially if it is sustained? When is the prognosis good?
1) Prognosis depends on the presence of heart disease and on whether VT is sustained or nonsustained
2) VT after an MI usually has poor prognosis, especially if it is sustained
3) In patients with no underlying heart condition, the prognosis is good
What are clinical features of VT?
1) Palpitations, dyspnea, lightheadedness, angina, impaired consciousness (syncope or near-syncope)
2) May present with sudden cardiac death
3) Signs of cardiogenic shock may be present
4) May be asymptomatic if rate is slow
5) Physical findings include cannon A waves in the neck (secondary to AV dissociation, which results in atrial contraction during ventricular contraction) and an S1 that varies in intensity
What does the ECG for VT show? What do QRS complexes look like? Does VT respond to vagal maneuvers?
1) ECG: Wide and bizarre QRS complexes
2) QRS complexes may be monomorphic or polymorphic
a) In monomorphic VT, all QRS complexes are identical
b) In polymorphic VT, the QRS complexes are different
3) Unlike PSVT, VT does not respond to vagal maneuvers or adenosine
What is key for treatment of VT?
Identify and treat reversible causes
How do you treat VT in hemodynamically stable patients with mild symptoms and systolic BP > 90?
1) Use pharmacologic therapy
2) New advanced cardiac life support (ACLS) guidelines recommend IV amiodarone, IV procainamide, or IV sotalol
How do you treat VT in hemodynamically unstable patients or patients with severe symptoms?
1) Immediate synchronous DC cardioversion
2) Follow with IV amiodarone to maintain sinus rhythm
Ideally, what should all patients with sustained VT undergo?
Placement of an ICD, unless EF is normal (then consider amiodarone)
How do you treat nonsustained VT if there is no underlying heart disease and the patient is asymptomatic?
1) Do not treat
2) These patients are not at increased risk of sudden death
How do you treat nonsustained VT if the patient has underlying heart disease, a recent MI, evidence of left ventricular dysfunction, or is symptomatic?
1) Order an electrophysiologic study
2) If it shows inducible, sustained VT, ICD placement is appropriate
When should you use pharmacologic therapy in the setting of nonsustained VT? What agent should be used?
1) Pharmacologic therapy is second-line treatment
2) However, amiodarone has the best results of all of the antiarrhythmic agents
