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when an automaticity foci has an entrance block, and paces but cannot be overdrive suppressed

irregular rhythms

usually caused by multiple active automaticity sites

entrance block

blocks incoming depolarization in automaticity foci, cannot be overdrive suppresed

wandering pacemaker

an irregular rhythm produced by the pacemaker activity wandering from the SA Node to nearby atrial automaticity foci

wandering pacemaker

p' wave shape varies, atrial rate less than 100, irregular ventricular rhythm

P' wave

atrial depolarization by an automaticity focus, as opposed to normal sinus-paced p waves

multifocal atrial tachycardia (MAT)

irregular rhythm, p' wave shape varies, atrial rate exceeds 100, irregular ventricular rhythm

multifocal atrial tachycardia (MAT)

a rhythm of patients with Chronic Obstructive Pulmonary Disease (COPD), with P' waves of different shapes, since three or more atrial foci are involved

atrial fibrillation

irregular rhythm, continuous chaotic atrial spikes, irregular ventricular rhythm

atrial fibrillation

caused by the continuous rapid-firing of multiple atrial automaticity foci. no single impulse depolarizes the atria completely and only occasional ones reach AV node to be conducted to ventricles, no p waves

sinus arrhythmia

considered normal, varies with respiration, constant p waves

escape rhythm

an automaticity focus escapes overdrive suppression to pace at its inherent rate

escape beat

an automaticity focus transiently escapes overdrive suppression to emit one beat, due to sinus block

sinus arrest

when a sa node ceases pacemaking completely

junctional automaticity focus

pacing from av node, conducts to ventricles, may depolarize atria from below producing inverted p' waves with an upright qrs

junctional automaticity focus

retrograde (inverted) p' wave immediately before each qrs, after each qrs, or within each qrs

stoke's adams syndrome

pacing from ventricular focus so slow that blood flow to the brain is reduced to the point of unconsciousness

ventricular escape beat

produces enormous QRS complex, caused by burst of parasympathetic activity that depresses SA node and atrial and junctional foci

premature beat

originates in an irritable automaticity focus that fires spontaneously, producing a beat earlier than expected in the rhythm

atrial, junctional

____ and ____ foci become irritable bc of adrenaline, increased sympathetic stimulation, caffeine, digitalis, hyperthyroidism, (adrenergic substances) stretch, low O2

premature atrial beat (PAB)

originates suddenly in an irritable focus, produces a P' wave earlier than expected, or hides in T wave, making it taller than usual


a center of automaticity ____ its rhythm when it is depolarized by a premature stimulus

aberrant ventricular conduction

if ventricular conduction system is depolarized by a Premature Atrial Beat but one Bundle Branch is not completely repolarized (still a little refractory), produces slightly widened QRS for one cycle


a ________ premature atrial beat is unable to depolarize a refractory AV node, no ventricular (QRS) response, does depolarize SA node to reset the pacemaking cycle

atrial bigeminy

an irritable automaticity focus fires a Premature Atrial Beat that couples to the end of a normal cycle, and repeats this process by coupling a PAB to the end of each successive normal cycle, resets cycle


the cycle containing the premature beat together with the cycle or cycles to which it couples

atrial trigeminy

when an irritable atrial focus prematurely fires after 2 normal cycles repeatedly

premature junctional beat

when an irritable focus in the av junction spontaneously fires a stimulus, widened qrs

junctional bigeminy

when an irritable junctional focus fires a premature stimulus coupled to the end of each normal cycle

junctional trigeminy

when an irritable junctional focus fires a stimulus after two consecutive normal cycles


a _____ focus can be made irritable by low O2, Low K+, pathology (mitral valve prolapse)

Premature Ventricular Complex (PVC)

produced on EKG by irritable ventricular focus that suddenly fires, occur early in cycle, easily recognized by their great width and enormous amplitude, usually opposite polarity of normal QRS, weaker pulse bc ventricles aren't filled yet


6 or more PVCs per minute is pathological, if they are identical, they are _____ (from the same focus)

ventricular bigeminy

when a PVC becomes coupled with a normal cycle with every cycle

ventricular trigeminy

when a PVC couples with every two normal cycles

ventricular parasystole

produced by a ventricular automaticity focus that suffers from an entrance block that is not irritable. not vulnerable to overdrive suppression

ventricular tachycardia

a run of three or more PVC's in rapid succession, if lasts longer than 30 seconds it is sustained

mitral valve prolapse (MVP)

causes PVC's, including runs of VT and multifocal PVC's, yet it is considered a benign condition, the mitral valve is floppy and billows into left atrium during ventricular systole

R on T phenomenon

if a PVC falls on a T wave, particularly in situations of hypoxia or low serum potassium, dangerous arrhythmias may result


rapid rhythms originating in very irritable automaticity foci

paroxysmal tachycardia

tachyarrhythmia from 150 to 250 bpm


tachyarrhythmia from 250 to 350 bpm


tachyarrhythmia from 350 to 450 bpm

paroxysmal tachycardia

a very irritable automaticity focus suddenly paces rapidly (atrial, junctional, ventricular)

paroxysmal atrial tachycardia (PAT)

rate range from 150 to 250 bpm, P' waves that do not look like sinus generated P waves, normall appearing cycles

PAT with AV block

more than one P' wave spike for every QRS complex, suspect digitalis excess or toxicity, atrial foci are very sensitive to digitalis

paroxysmal junctional tachycardia (PJT)

rate range from 150 to 250, may depolarize atria from below in retrograde fashion with inverted P' wave before, after, or buried within each QRS complex, may be widened QRS

AV nodal reentry tachycardia (AVNRT)

type of junctional tachycardia, a continuous reentry circuit develops and rapidly paces the atria and ventricles

paryoxysmal supraventricular tachycardia (SVT)

includes PAT and PJT, all foci above ventricles

paryoxysmal ventricular tachycardia (PVT)

rate range from 150 to 250, characteristic pattern of enormous, consecutive PVC-like complexes, SA node still paces the atria,

fusion beat

a blending on the EKG of a normal QRS with a PVC-like complex, confirms the diagnosis of VT

torsades de pointes

peculiar form of very rapid ventricular rhythm caused by low potassium, medications that block potassium, or congenital abnormalities, lengthen the QT segment, rate between 250 and 350 bmp, usually in brief episodes, outline looks like a twisted ribbon

atrial flutter

extremely irritable atrial automaticity focus fires at 250 to 350 bpm, producing a rapid series of atrial depolarizations,identified by inverting tracing or vagal maneuvers

ventricular flutter

rate range of 250 to 350 bpm, produced by a single ventricular automaticity focus, produces a rapid series of smooth sine-waves of similar amplitude, ventricles dont have time to fill, rapidly becomes deadly

Atrial fibrillation (AF)

rate range of 350 to 450 bpm, caused by many irritable parasystolic atrial foci, rapid erratic atrial rhythm with irregular ventricular response, may just look like irregular baseline with irregular QRS complexes

ventricular fibrillation

rate range of 350 to 450 bpm, caused by rapid-rate discharges from many irritable, parasystolic ventricular automaticity foci, erratic, rapid twitching of ventricles, no effective cardiac output

cardiac standstill (asystole)

occurs when there is no detectable cardiac activity on EKG, rare, the SA node and the escape mechanisms of all the foci at all levels are unable to assume pacing responsibility

pulseless electrical activity (PEA)

present when a dying heart produces weak signs of electrical activity on EKG but the heart cannot respond mechanically (no detectable pulse)

automated external defibrillator (AED)

small portable unit for defibrillation

implantable cardioverter defibrillator (ICD)

implanted under skin delivers shock if needed automatically

WPW (wolff-parkinson-white) syndrome

an abnormal accessory Bundle of Kent short-circuits usual delay of AV node and causes ventricular pre-excitation, produces delta wave on EKG just before normal ventricular depolarization begins

(lown-ganong-levine) LGL syndrome

the AV node is bypassed by an extension of the anterior internodal tract. without the AV node conduction delay, this "James bundle" conducts atrial depolarizations directly to the His Bundle without delay,


retard or prevent the conduction of depolarization, may occur in SA node, AV node, His bundle, Bundle Branches, Left Bundle Branch

sinus block

an unhealthy sa node stops pacing for at least one complete cycle, may induce an escape beat from an automaticity focus

SSS (sick sinus syndrome)

a wastebasket of arrhythmias caused by SA node dysfunction associated with unresponsive supraventricular automaticity foci, which are also dysfunctinoal and can't employ their normal escape mechanism to assume pacing responsibility, marked bradycardia

Bradycardia-Tachycardia Syndrome

when patients with SSS develope intermittent episodes of SVT mingled with sinus bradycardia

first degree AV block

retards AV node conduction, prolongs PR interval more than one large square, PR interval is consistently prolonged the same amount every cycle and following sequence is normal

second degree AV block

allows some atrial depolarizations to conduct to the ventricles, while some atrial depolarizations are blocked, leaving lone P waves, 2 types

Wenckebach blocks

second degree blocks of AV node, produce a series of cycles with progressive blocking of AV node conduction until the final P wave is totally blocked in the AV Node, eliminating the QRS complex, consistent P:QRS ratio like 3:2, 4:3, etc, innocuous

Mobitz blocks

second degree blocks of Purkinje fiber bundles, produce a series of cycles consisting of one normal P-QRS-T cycle preceded by a series of paced P waves that fail to conduct through the AV node. ratios like 3:1, 4:1, 5:1, pathological, widened QRS


if there is a 2:1 av block and parasympathetic stimulation has no effect of eliminates block, it was a _______ block


if there is a 2:1 av block and parasympathetic stimulation increases the number of cycles/series, it was a _______ block

third degree AV block

completely blocks AV conduction, automaticity focus below the block escapes to pace the ventricles at its inherent rate

downward displacement of the pacemaker

the failure of all automaticity centers above the ventricles-bad prognosis

bundle branch block (BBB)

caused by a block in the right or left bundle branch, the blocked branch delays depolarization to the ventricle that it supplies, causes two joined QRS's on the EKG, QRS is 3 small squares (.12s) or greater, and there are 2 R waves

intermittent mobitz

occasional dropped qrs due to permanent BBB (one side) with intermittent BBB of the other side


a block of one of the two subdivisions (fasicles) of the left bundle branch, commonly occurs with infarction

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