12-lead exam 2

frequency of occurrence

denotes the clinical significance of atrial arrhythmias

main characteristic of sinus arrythmia

normal respiratory cycle but irregular rhythym (more than .06 sec between r-r or p-p)

what denotes an irregular rhythym

more than 0.06 sec difference in r-r intervals

supraventricular tachycardia

fast heart rate with NO P wave present but normal QRS complex

40-60 bpm

rate range for a junctional beat

5 areas associated with interpreting ECGs

rate, rhythm, infarction, hypertrophy, axis

wandering pacemaker main characteristic

Site of impulse formation shifts; P wave changes configuration

Characteristics of a wandering pacemaker

variable rate (WNL), slightly varied rhythm, changing P, varible P-R (junctional if <.12)

PAT meaning

paroxysmal atrial tachycardia

rate range for PAT

150-250 bpm

abrupt or sudden

onset or stoppage of PAT

underlying rhythm and QRS range are ______ in PAT

normal or WNL

PAC meaning

premature atrial contraction

PAC cause

ectopic foci fires before the SA node leading to an extra or early beat

PAT main characteristic

P wave fires early and moves QRS complex up; shorter P-R interval

6 PACs

denotes atrial tachycardia

non-conducted PAC

the early P wave is NOT followed by a QRS

PAC underlying rate and rhythm are ____

normal

conducted PAC

premature P IS followed by a QRS

compensatory pause in PAC

equal or longer distance of the PAC beat complex to a normal 3-beat complex

non-compensatory pause in PAC

shorter distance of the PAC beat complex to a normal 3-beat complex

what to measure for a PAC pause

2 complexes of 3 beats”

1) 3 normal beats

2) normal, pac beat, normal

sinus block

a complete missed beat (P, QRS and T) that returns to normal rhythm

sinus arrest

a complete missed beat (P, QRS and T) that does NOT return as normal; prolonged pause

sinus arrest and sinus block have _____ rate (____) and rhythm except during the pause

normal, 60-100bpm

atrial fibrillation P wave characteristic

wavy line, not discernible

atrial fibrillation rate range

350-650

cause of a-fib

multiple very irritable foci

a-fib coarse vs fine waves

• coarse: 1mm or more

• fine <1mm

a-fib ecg characteristics

fast rate (350-650), no P, normal QRS, irregular rhythm, no P-R interval

controlled conduction in a-fib

rate < 100bpm

uncontrolled conduction in a-fib

rate >100 bpm

atrial flutter P wave characteristic

saw-tooth pattern

atrial flutter ecg characteristics

irregular rate, normal QRS, non-discernible P rate or P-R interval, fast rate(250-350)

a-flutter rate range

250-350

a-flutter conduction ratios

(determined by # of Ps before and within QRS)

• fixed - same # of flutter Ps (r-r interval is regular)

• variable - varying # of flutter Ps (r-r interval is irregular)

in atrial flutter, rhythm can be regular or irregular based on what?

the conduction ratio

P wave ‘specs’

present, regular rhythm, matched to each QRS, shape of P, shape similarity

P-R Interval ‘specs’

shorter than .12, longer than .20, constantcy

QRS ‘specs’

less than .12, similarity/constancy, rhythm

sinus bradycardia

sinus rate less than 60 bpm (normal everything else)

causes of sinus bradycardia

• athletic conditioning

• hypothyroidism or hypoxia

• hyperkalemia

• after acute infarction

• increased cranial pressure

• increased vagal tone

• dig toxicity

sinus tachycardia

sinus rate of 100-160bpm, normal everything else

causes of sinus tachycardia

• exercise, pain, stress

• substances: caffeine, alc, nicotine

• heart failure, shock, fever

• pulmonary embolism

• hyperthyroidism

causes of sinus arrhythmia

• athletes

• reflex vagal tone to normal respiratory cycle

• SSS in elderly

3 P wave configuration in junctional rhythms

inverted, absent/merged, retrograde

junctional rhythm rate range

40-60

accelerated vs tachycardic vs bradycardic junctional rates

• accelerated = 61-100bpm

• tachycardia = 101-150 bpm

• bradycardia = < 40bpm

junctional rhythms have regular _____ (R-R regularity) and normal _____

rhythms, QRS timing

P-R interval in junctional rhythms

shortened to <.11 or not identifiable

PJC meaning

premature junctional contraction; premature beat with impulse formation in the AV junction

PJC ecg characteristics

P wave variation, short P-R, QRS<.12 or normal

PAC vs PJC

• pause with early or odd shape P wave (p wave still must occur)

• pause with varying-configuration or absent P wave

top nodal PJC presentation

P wave occurs inverted before the QRS

middle nodal PJC presentation

P wave is absent or occurs inside the QRS complex

low nodal PJC presentation (retrograde)

P wave occurs upright or inverted after the QRS complex

wandering pacemaker look-alike

many PJCs occurring in the same ecg