SVT Flashcards
What does true heart rate depend on?
AV node conduction and subsequent ventricular contraction
Most common therapies in SVT.
Meds that slow AV conduction
- adenosine
- Beta Blockers
- CCB (diltiazem, verapamil)
- digoxin
What are the 3 electrical etiologies for SVT?
- Increased Automaticity
- Re-entry
- Triggered Activity
What are the 3 anatomical locations for etiologies of SVT?
- SA node
- Atria
- AV node or Junction
Treatment for physiological sinus tachycardia.
Usually a secondary cause (emotion, exercise, fear, infection). Treatment involves the treating the underlying cause.
Treatment for inappropriate Sinus Tachycardia.
Usually electrical or neuronal cause.
-Treat with beta blockers or ablation of irritated foci
Difference between Re-entry Sinus tachycardia and the other two types.
Re-entry ST is paroxysmal, the other two are gradual onset.
Most common type of Paroxysmal SVT.
AV node Reciprocating Tachycardia (AVNRT): caused by re-entry
Name and describe the two types of AVNRT.
Typical: slow pathway conducts impulse from atria to ventricles, short RP interval
Atypical: fast pathway conducts signal from ventricles to atria, long RP interval
Tx for AVNRT
If Stable: vagal maneuvers, adenosine, ablation (long term).
If unstable: defibrillator (DC cardioversion)
Tx for junctional tachyarrhythmias.
Beta blockers, ablation
Non-paroxysmal Junctional tachycardia is a benign condition, why is it medically relevant?
Can be a marker for a more serious underlying condition: digoxin toxicity, COPD, hypokalemia, hypoxia etc.
What is AV Re-entry tachycardia?
Re-entry that uses Extra-Nodal Pathways
-Can create delta waves or absolutely no PR segment. P waves terminates and immediately the QRS begins
What type of AVRT is considered Wolff-Parkinson-White syndrome?
Pre-excitation (delta wave) of QRS along with Tachycardia (>100bpm)
What are the two types of pathway conductions in AVRT?
Orthodromic: signal travels down the AV node pathway then back up the extra nodal tissue.
Antidromic: signal travels down the extra nodal tissue then back up the AV node tissue
Treatment for WPW.
Ablation of the extranodal tissue
Main medication used to treat general AVRT.
Procainamide
How is focal atrial tachycardia differentiated from flutter or fibrillation?
The baseline between the T wave and P wave is isoelectric
Two causes for Focal Atrial Tachycardia and treatments for each.
Re-entry: ablation
Foci Irritation: meds
How is Multifocal Atrial Tachycardia diagnosed on EKG and what are common conditions associated with it?
EKG: multiple P wave shapes
Associated with pulmonary disease, metabolic disease, electrolyte imbalance
Tx for Multifocal Atrial Tachycardia
Calcium Channel Blockers
Most common cause of atrial flutter.
Cavotriscupid Isthmus: piece of conducting tissue by the IVC and tricuspid valve that allow re-entry into the atria for multiple fast depolarizations
What is an important long term treatment for atrial flutter?
Anticoagulants: clots tend to form due to blood stasis in the atria, they can embolize and go to the lungs
