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42 Cards in this Set
- Front
- Back
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SA Node
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*located rt atrium at the junction of the SVC & rt atrium
*intinsic rate: 60-100 x/min *pm of the heart |
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How are impulses spread from the SA node through the atrial chambers?
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Internodal tracts
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AV node
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*floor of the rt atrium near the junction of interatrial and interventricular septa
*slows conduction=atrial kick, packing (30% of ventricular filling); protects ventricle from fast arrythmias |
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Bundle of His
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*inferior portion of the AV node
*passes thru the IV septum |
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AV junction
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*PM cells generate impulses 40-60 x/min
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Bundle branches
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*traverse the IV septum to the left and right ventricle
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Purkinje network
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*arises from the terminal branches of the bundle braches
*conduct impulses to mechanical cells of the myocardium *PM cells umpulse at rate 40 x/min |
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depolarization
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Mvmt of sodium and calcium to the inside of the cell
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repolarizaiton
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Occurs wehn the electrical celss return to their resting state
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A positive deflection occurs
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when an impulse moves toward the + electrode
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When an impulse moves away from the + electrode...
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a - deflecitons will be recorded
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Lead II
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the + electrode is placed over the 4th-5th ICS/MCL(apex)
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depolarization of atrial cells
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p wave
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PR segment
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the time the impulse takes to pass thru the AV junction, isoelectric
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PR interval
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time required for the impulse to depolarize the atria, travel thru AV node and B of H to the ventricles.
Measured at the beginning of the P to the beginning of the QRS complex. NORMAL: 0.12 sec to 0.20 sec. |
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*depolarization of the ventricular cells
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QRS complex
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QRS width
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*amt of time impulse to traverse the r/l ventricles
*NORMAL: 0.10 sec or less |
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ST segment
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*represents the beginning of ventricular repolarization (phase 1 and 2)
*isoelectric |
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T wave
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*represents last 2 phases of ventricular repolarizaiton
*upright, round deflection |
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measures how long it takes the ventricle to depolarize and repolarize
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QT interval
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QT interval
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*varies with gender, age and HR
*beginning og QRS to end of the T wave |
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3 steps to ID basic rhythm
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1) ID the PM site
if p waves, measure PRI < 0.12 sec = SA node/atria > 0.12 sec = AV junction 2) look for evidence of conduction delay/HB PRI > 0.20 sec QRS > 0.10 sec P waves w/o QRS complexes atrial rate>ventricular rate 3) ID PM of any premature beats atria, av junction or ventricles |
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Asystole
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Origin: NO electrical act'y
Conduction: N/A Features: flat, baeline Hemodynamic effect: NO cardiac output Tx: CPR, epi, intubate. Check 2nd lead (r/o v-fib). |
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ventricular fibrillation
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Origin:
Conduction: PM is several sites in the ventricle Features: chaotic, wavy, undulating baeline Hemodynamic effect: NO cardiac output Tx: defibrillation, epi, lidocaine, CPR |
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NSR
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Origin: SA node, depolarizing 60-100 x/min
Conduction: conducted thru atria, AV junction, ventricles. PRI 0.12-0.20sec, QRS 0.10 or less. Features: atrial rate = 60-100/min; PRI 0.12 sec or greater Hemodynamic effect: NAE Tx: n/a |
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sinus tachycardia
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Origin:SA node
Conduction: thru AV junction and ventricles nml/abnml Features: atrial rate 101-150/min; PRI 0.12 sec or > Hemodynamic effect: de/increased CO (individualized) Tx: usually secondary to stimulation of SNS, direct tx toward specific cause (fear, pain, anxiety, shock, infection) |
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sinus bradycardia
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Origin: SA node
Conduction: thru AV node nml/abnml. Features: atrial rate < 60/min; PRI 0.12 sec or > Hemodynamic effect: in/decrease CO, may be protective post-MI Tx: increase rate w/atropine and pacing if symptomatic |
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sinus block
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Origin: SA NODE
Conduction: abnl thru the SA node, the SA node fires but the impulse to the atria is blocked = pause. Features: complete absence of P wave, QRS complex and T wave creating a pause in the rhythm Hemodynamic effect: varies w/frequency Tx: if symptomatic, atropine/pacing |
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sinus arrythmia
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Origin: SA node, normal variation seen w/respiratory cycle
Conduction: may be nml/abnml Features: P-P irregular; difference b/t shortest and longest P-P interval is 0.12 sec or GREATER Hemodynamic effect: n/a Tx: n/a |
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1st degree block
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Origin: SA node, abnormality seen in NSR, SB, ST
Conduction: abnormal thru the AV junction (usually the AV node), every impulse is conducted to the ventricles but conduction takes longer Features: every P wave is followed by QRS; PRI > 0.20 sec Hemodynamic effect: n/a Tx: observe for progression |
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2nd degree block
Type I or Wenkebach |
Origin: SA node, occurs w/ NSR, SB, ST
Conduction: impulse is conducted abnormally thru AV junciton, usually at the node, progressive delay in conduction until an impulse is not generated to the ventricles. PRI lenghtens. The impulse generated to the ventricles is usually normal Features: P-P regular; R-R IRREGULAR; PRI lenghtens until a P wave appears w/o QRS complex; QRS width is 0.10 sec or less Hemodynamic effect: effect is dependent on ventricular rate Tx: if v. rate is too slow to maintain an adequate CO then atropine and/or pacing |
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2nd degree
Type II |
Origin: SA node, occurs w/NSR, SB, ST
Conduction: conduciton delay is below the AV node, usually produces a WIDE QRS. Features: P-P reg; R-R irreg or reg; PRI constant/< 0.20 sec; EVERY P WAVE DOES NOT HAVE A QRS COMPLEX; QRS WIDTH > 0.20 SEC Hemodynamic effect: determined by the ventricular rate Tx: pacing, observe for progression to CHB |
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2nd degree
w/ 2:1 conduction pattern |
Origin: SA node, occurs w/ a sinus rhythm
Conduction: exists when EVERY OTHER sinus impulse is blocked and not conduted to the ventricles. VENTRICULAR RATE IS 1/2 ATRIAL RATE. Features: P-P reg, R-R reg, PRI constant, v rate is 1/2 a rate, EVERY OTHER P WAVE IS FOLLOWED BY QRS COMPLEX Hemodynamic effect: determined by the ventricular rate Tx: based on the location of the block and the actual ventricular rate. pacing and/or drugs may be necessary to maintain adequate CO |
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determine location of 2nd block w/2:1 conduciton
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2nd degree, Mobitz I
(block in AV node) PRI > 0.20 sec QRS width 0.10 sec or less 2nd degree, mobitz II (block in ventricles) PRI 0.20 sec or less QRS width > 0.10 sec |
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3rd degree block
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Origin: TWO SEPARATE RHYTHMS, one SA and AV junction or ventricles
Conduction: NO CONDUCITON THRU THE AV JUNCTION OR THE BB Features: P-P reg, R-R reg, PRI varies Hemodynamic effect: CO is decreased Tx: pacing |
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atrial tachycardia
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Origin: atrial
Conduction: if conduction normal, p wave then QRS w/ 1:1 conduction and PRI > 0.12sec. if abnormal thru AV junction, some impulses will be blocked. This prevents rapid ventricluar rates = atrial tachycardia w/block Features: ATRIAL RATE 151-250/min; PRI 0.12 sec if 1:1; P-P reg; R-R reg/irreg; QRS width normal Hemodynamic effect: usually decreased Tx: is directed at controlling the number of impulses delivered to the ventricles. ADENOSINE, PROPANOLOL, METOPROLOL, DIGITALIS. |
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ATRIAL FLUTTER
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Origin: ATRIA
Conduction: ABNORMAL thru atria and AV junction Features: atrial rate 251-400/min; saw toothed baseline; P-P regular; R-R reg/irregular Hemodynamic effect: decreases CO Tx: control v rate or convert. ADENOSINE, PROPANOLOL, METOPROLOL, DIGITALIS. |
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ATRIAL FIBRILLATION
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Origin: ATRIA
Conduction: RAPID ATRIAL DEPOLARIZATION, AV JUNCTION IS BOMBARDED W/IRREG IMPULSES, RANDOMLY CONDUCTS SOME IMPULSES TO VENTRICLES Features: P WAVES NOT IDENTIFIABLE; R-R IRREGULAR Hemodynamic effect: MAY DECREASE CO, DEPENDING ON V RATE Tx: CONTROL V RATE OR CONVERT. PROPANOLOL, METOPROLOL, DIGITALIS. |
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JUNCITONAL RHYTHM
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origin:
conduction: AV JUNCTION features: PRI<0.12 SEC -> A THEN V 2) V -> A THEN RETROGRADE P WAVE USUALLY FOUND IN ST SEGMENT 3) A AND V ARE DEPOLARIZED AT THE SAME TIME. ALL 3, THE ATRIA IS IMPULSE IS REC'D BY THE ATRAI IN RETROGRADE FASHION. QRS <0.10 VENTRICULAR RATE IS 40-60/MIN hemodynamic effect: MAY DECREASE CO B/C LOWER V RATE tx: RESTORE SA NODE AS THE PRIMARY PM, OR INCREASE RATE TO INCREASE CO |
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ACCELERATED JUNCTIONAL
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ORIGIN: AV JUNCTION
CONDUCTION:IMPULSE IS CONUCTIED RETROGRADE TO ATRIA AND ANTEGRADE TO VENTRICLES. THE RELATIONSHIP OF THE P WAVE AND QRS COMPLEX ARE DETERMINES BY THE ACTIVATION OF THE ATRIA AND VENTRICLES. FEATURES: RATE 61-100/MIN; QRS NORMAL 0.10SEC OR LESS HEMODYNAMIC EFFECT: CO USUALLY NOT EFFECTED TX:N/A UNLESS CO IS INADEQUATE |
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JUNCITONAL TACHYCARDIA
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ORIGIN:
CONDUCTION: AV JUNCTION FEATURES: VENTRICULAR RATE IS > 100/MIN HEMODYNAMIC EFFECT: CO USUALLY WILL DECREASE B/C FAST RATE AND INAPPROPRIATE ATRIAL CX/PACKING. TX:PROCAINAMIDE, DIGITALIS, BETA BLOCKERS ARE USED WHEN THE CO IS AFFECTED SECONDARY TO FASTER RATE. |
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JUNCTIONAL ESCAPE BEAT
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ORIGIN: AV JUNCITON
CONDUCTION: SAMES AS JUNCTIONAL RHYTHM FEATURES: LATE QRS THAT FOLLOWS A PAUSE IN THE RHYTHM, P WAVE VARIES, QRS 0.10 SEC OR >. HEMODYNAMIC EFFECT: IMPROVE CO TX: N/A |
