what kind of disorders are altered automaticity and triggered activity?
disorders in impulse formation
altered automaticity can occur in what kind of cells?
normal pacemaker cells and myocardial working cells that do not normally function as pacemaker sites. these cells depolarize and initiate before a normal impulse
when does triggered activity happen and what does it require?
during repolarization when cells are normally quiet and requires a stimulant to initiate depolarization
what is reentry?
a condition in which an impulse returns to stimulate tissue that was previously depolarized?
what does reentry require?
a potential conduction circuit or circular conduction pathway, a block within part of the circuit, delayed conduction with the remainder of the curcuit
what does reentry result in?
a single premature beat or repetitive electrical impulses resulting in short periods of rapid rhythms
characteristics of the p wave in a PAC
biphasic, flattened, notched, pointed, lost in the proeceding t wave
if the normal beat following the premature complex occurs before it was expected
when a PAC occurs very early and close to the preceding t wave (only a p wave may be seen with no QRS after it appearing as a pause) it is called...
nonconducted or blocked PAC
what varies in a wondering pacemaker?
the differences in p wave configuration reflect gradual shifting of the dominant pacemaker b/t the SA node, the atria and the AV junction. at least 3 different p wave configurations in the same lead are required for diagnosis
what is it called when wondering atrial pacemaker is associated with a vent rate <100?
multifocal atrial tachycardia
what are 7 vagal maneuvers?
coughing, squatting, holding your breath, carotid sinus massage, cold stimulus to the face, valsalva maneuver, gagging
what are the characteristics of adenosine?
can interrupt reentry pathways that involve the AV node, rapid onset of action, short half-life, slows hr
what are supraventricular arrhythmias?
rhythms that begin above the vifurcation of the bundle of His. this includes the SA node, atrial tissue and AV juction