Tachycardia

 

 

Reentry Rhythm

need slow conduciton in one limb and unidirectional block in the other

 

<<PIC>>

 

 

automaticity

abnormal transmembrane leak depolarizes cells too early.

 

triggered activity

common

calcium overloading of cells results in membrane potential oscillation which can trigger activation. This is through the Na-Ca exchanger, which can move both ions in both directions. Delayed afterdepolarization

 

Supraventricular tachycardias

narrow QRS complexes

 

Sinus Tachycardia

physiologic.

exercise, epinephrine, blood loss

 

 

Atrial Fibrillation/

extremely common; 5% of people over 70, 10% of people over 80%

very frequent atrial ectopy can trigger fribrillation, using triggered or automatic.

an abnormal atrium, scarred and stretched, is easily put into fibrillation by triggers, due to easy reentry

irregularly irregular rapid pulse.

AV node will only allow so many beats through.

young folks ~200 bpm, deacreases with age.

 

can cause atrial thrombus in appendage

 

can also get tachycardia-induced cardiomopathy

 

some people can be asymptomatic. other people feel terrible. symptoms can include angina (if with CAD), CHF (if with valvular disease), fatigue, syncope/lightheadedness

 

Treatment

Anticoagulation should be used if there is increased risk of

 

 

Atrial Flutter

macroreentry

electrical activity loops around right atria around

 

AV Nodal Reentry

most common (60%) cause of paroxysmal SVT

inputs to AV node from atrium can have different enough properties to cause atrial reentry

excellent prognosis, but can be annoying

 

AV Reentry

accessory pathway across valvular

30% of paroxysmal SVT

 

ectopic atrial tachycardia

triggered or automatic focus

 

 

Ventricular

usually activated through muscle itself - reentry, generating a wider QRS

most ventricular tacy occurs in the setitng of a prior MI. Surviving tracts within infarction scar....

monomorphic, polymorphic, or Torsades des Pointes

 

 

others

 

 

Treatments

paroxysmal SVT

atrial fibrillation and flutter

ventricular tachycardia