McCarthy EKG Flashcards
a normal P wave axis lies between what two degrees? (for adults and children)
0 and +70 for adults
0 and +90 for kids
lead II’s positive electrode is at what degree?
+60
what is the isoelectric line?
flat line between beats when there is no electrical activity
beats originating in the SA node should generate what type of P wave?
upright (seen in lead II)
what two arrhythmias are seen with a wide complex?
ventricular arrhythmia or SV arrhythmia aberrant
BPM for SA node, atria, AV node, ventricles
SA- 60-100
Atria- 60-75
AV- 40-60
ventricles- 30-45
how does the action potential spread from the SA node to left and right atria?
via the atrial internodal tracts
why is conduction through the AV node slow?
to insure that the ventricles have enough time to fill before they are activated and contract (has a refractory period)
what three things does increasing the conducting velocity of the AV node lead to?
decreased ventricular filling, stroke volume, and cardiac output
what makes up the AV junction?
AV node and bundle of His
junctional pacemaker cells = ?
AV node
what makes up the ventricular conducting system?
right and left bundle branches plus purkinje system
what is an ectopic pacemaker?
when failure of the SA node leads to another pacemaker taking over and setting the new rhythm
besides SA node failure, how could other pacemaker cells (besides the SA node) take over?
altered automaticity- events that increase automaticity such as myocardial ischemia, increase sympathetic tone, HYPOkalemia
describe escape or premature beats narrow complex VS wide complex
narrow complex escape/premature beats arise from above the bundle branches (AV node or atrium); wide complex beats are originating in the ventricles
what is an escape beat?
rescue beats taking over rhythm from SA node (ALWAYS a pause before escape beat)
is a P wave seen with an escape beat?
not usually since the pacemaker cell isn’t the SA node (and can hide within the QRS complex)
narrow vs wide complex numbers?
narrow is less than 0.12 sec
wide is greater than 0.12 sec
what is a premature beat?
a beat that occurs early within normal sinus rhythm
atrial vs junctional premature beat
atrial p wave occurs early and ABNORMAL contour
junctional occurs early but usually doesn’t have p wave (sometimes retrograde, inverted)
what are the three types of junctional rhythms?
1) . inverted p wave before QRS- atria depolarizing from bottom to top before ventricles depol
2) . atria and ventricles depolarizing at same time- p wave hidden in QRS
3) . inverted p wave after QRS- atria depolarizing bottom to top after ventricles depol
NSR PR interval and QRS complex
PR interval- 0.12-0.2 sec
QRS- NARROW (<0.12)
sinus tachy and sinus brady rates
tachy: 100-160
brady: 40-60
PSVT also called what two things?
AV nodal reentry tachycardia
Paroxysmal atrial tachycardia
PSVT: complex? rate? p waves?
narrow complex tachy, 150-250 bpm, usually no p waves seen (grouped with T wave)
what is PSVT usually initiated by?
a premature supraventricular beat (atrial or junctional)
atrial flutter: complex? rate? p wave? pattern?
narrow complex tachy, 250-350 rate, multiple p waves between QRS
“sawtooth”- no flat baseline
three different types of conduction rates for atrial flutter?
variable- differing amounts of atrial vs ventricle rates
4: 1- 4 p waves to every 1 QRS
2: 1- 2 p waves for every 1 QRS
Afib: complex? rate? p waves? ventricle rate?
narrow complex tachy, >350 rate, no true p waves, ventricle rate is irregularly irregular (only occasional impulses passed from atria to ventricles)
what are the two main types of afib?
controlled rate (<100 BPM) vs uncontrolled rate (>100 BPM)
BBB- complex? rate? p wave?
WIDE complex, tachy rate, sinus p wave (if significant tachy, p waves might be buried in T wave)
PVC: complex? p wave? what is a PVC?
wide complex, usually no p wave seen
PVC: premature ventricular contraction
what is an escape ventricular beat?
PVC looking ventricular contraction that occurs after a pause (OCCURS LATE- compared to PVC)
should a ventricular escape rhythm be suppressed?
NO, could be life saving if its the only pacemaker the heart has left
what is ventricular tachy? complex? rate? p waves?
run of 3 or more PVC’s in a row; WIDE complex tachy, 140-250 rate, no p waves
what is often seen in VT waves?
ST segment and T wave slope opposite direction than the deflected QRS
what is monomorphic vs polymorphic VT?
monomorphic- all the QRS complexes have the same appearance
polymorphic- varying amplitudes, shapes sizes
what is ventricular escape rhythm?
pause and then ventricles take over pacing
what three electrolyte imbalance can cause Torsades? why?
Hypocalcemia- because it prolongs the QT interval
hypokalemia and hypomagnesemia
what is torsades? how is it usually started?
it is polymorphic VT with prolonged QT interval; usually started by a premature PVC falling on a prolonged T wave
Vfib: complex? rate? p wave?
wide complex tachy, undistinguishable rhythm, NO p waves, QRS or T waves
NO ASSOCIATED PULSE
first degree heart block: complex? special criteria?
narrow complex (unless BBB is present) **prolonged PR interval >0.2 seconds every p wave has a corresponding QRS
second degree heart block: two types? difference between the two?
Mobitz 1 “wenckebach” or Mobitz 2
- in both, a QRS is eventually dropped by PR interval in type 1 increases with every beat until QRS is gone (type 2= PR stays consistent)
Mobitz Type 1 complex? Type 2 complex? type 2 p waves?
type 1: narrow (unless BBB is present)
type 2: narrow or wide depending on site of block
type 2 p waves have multiple to every QRS
third degree heart block: complex? p waves?
narrow or wide; more p waves than QRS (looks like separation of p wave from t wave)
atrial vs ventricular rate for Type 1, 2nd degree heart block?
atrial- rate regular
ventricular- rate irregular
atrial vs ventricular rate for Type 2, 2nd degree block?
atrial- rate regular
ventricular- rate usually regular and a multiple of the atrial rate
atrial vs ventricular rate for 3rd degree block?
both rates usually regular (ventricular under 60 BPM)
what is asystole? what two ways can it present on EKG?
no ventricular activity, no QRS complexes EVER
presentation- as ONLY p waves or straight line
what is pulseless electrical activity (PEA)? what two things can it be due to?
an organized cardiac rhythm other than VT without a pulse
due to hypovolemia or hypoxia
what two things do you see with wolf Parkinson white?
PR interval less than 0.12
delta wave
what happens in wolf Parkinson white?
an accessory pathway called “bundle of kent” is used to bypass slow conduction of AV node
