click below
click below
Normal Size Small Size show me how
EKG Waveforms
Question | Answer |
---|---|
What is a normal PR interval? | 0.12-0.20 seconds |
What is a normal QRS? | 0.06-0.10 seconds |
What happens during P waves? | Atrial depolarization |
What happens during QRS waves? | Ventricular depolarization |
What happens during T waves? | Ventricular repolarization |
Characteristics of normal sinus rhythm (NSR) | * Rate: 60-100bpm * Rhythm: regular * 1P:1QRS * PR interval 0.12-0.20sec * QRS 0.06-0.10sec |
Characteristics of sinus tachycardia. | * same as NSR, with HR >100bpm. |
Characteristics of sinus bradycardia | * same as NSR< with HR <60bpm * do not treat unless patient is symptomatic. Treat with atropine 0.5mg or pacemaker therapy. |
Characteristics of premature atrial contractions (PACs) | * Rhythm is normal until interrupted by early beats from the atria, which makes the rhythm irregular * Usually requires no treatment; advise client to reduce ETOH and caffeine intake, reduce stress, and stop smoking (if applicable). |
Atrial tachycardia (supraventricular tachycardia, or SVT) | * Rate: 100-280bpm (~150-200bpm) * PR: unmeasurable * generally T-on-P waves * vagal maneuvers, adenosine, verapamil |
Atrial flutter | * Atrial rate 240-360bpm; ventricular usually <150bpm * P:QRS may be 2:1, 4:1, 6:1 or variable * PR unmeasurable * characteristic F (sawtooth) waves |
Atrial fibrillation | * Atrial rate 300-600bpm; ventricular 100-180bpm * Rhythm: irregularly irregular * P:QRS is variable * PR unmeasurable * f (fibrillatory) waves |
How is A-fib/A-flutter treated? | ABCDE - adenosine, beta blockers, CCBs, digoxin, electrocardioversion. If <48h duration, safe to cardiovert. If >48h, must anticoagulate first before cardioversion, unless hemodynamically unstable. |
Junctional rhythm characteristics | An inverted P wave either 1. before or 2. after the QRS. Can also have hidden P waves. |
Junctional rhythm (junctional escape rhythm) | * 40-60bpm * If P wave is present, PR is generally <0.10sec. * Treat if symptomatic. |
Accelerated junctional rhythm | * 60-100bpm |
Junctional tachycardia | * >100bpm |
Premature ventricular contractions (PVCs) | * Rate: variable * Rhythm: irregular, with PVC interrupting underlying rhythm followed by a compensatory pause. * P:QRS: no P before PVC * PR: absent with PVC. * QRS is wide, bizarre, >0.12sec. |
How are PVCs treated? | Treat is experiencing symptoms - IV lidocaine, procainamide, quinidine, propanolol. Avoid stimulant use. A RUN OF 3 OR MORE PVCS = RUN OF VTACH. |
Ventricular tachycardia (VT or VTach) | * Rate: 100-250bpm * Rhythm: regular * P waves usually not identifiable * PR not measured * wide, bizarre QRS, >0.12sec |
How is VT treated? | Treat if VT is sustained or client is experiencing symptoms - amiodorone or lidocaine. If pt is unconcious or unstable, immediate defib is required. |
Ventricular fibrillation (VF or VFib) | * rate: too rapid to count * rhythm: grossly irregular * no P waves, no PR * pt has *NO* CO! Call a code blue, DEFIB THE VFIB! |
1st Degree AV Block | * Rate usually 60-100bpm * Rhythm: regular * PR interval >0.20sec * Generally no treatment required. |
2nd degree AV block type 1, Mobitz I or Wenckebach | * Rate 60-100bpm * Rhythm atrial regular, ventricular irregular * PR interval progressively lengthens; absence of QRS at times * monitor; atropine or isproterenol if pt is symptomatic. |
2nd degree AV block type 11, Mobitz II | * atrial 60-100bpm, ventricular <60bpm * atrial regular, ventricular irregular * P:QRS typically 2:1, may vary * Atropine or isoproterenol; pacemaker |
3rd degree AV block (complete heart block) | * atrial 60-100bpm, ventricular 15-60bpm * atrial & ventricular regular * NO RELATIONSHIP BETWEEN P & QRS! * PR not measured. * QRS 0.06-0.10 if junctional escape rhythm, >0.12 if ventricular escape rhythm * immediate pacemaker therapy. |
Bundle Branch Block (BBB) | * delayed conduction through the bundle of His (ventricles) * Need 12-lead EKG to determine if R or LBBB * widened QRS, >0.12sec. Generally has a "rabbit ears" appearance. |
Difference between junctional rhythm w/ BBB and afib w/ BBB | * Junctional: no P waves, but REGULAR * Afib: no P waves, but IRREGULAR |
Bigeminal PVCs | PVCs that occur every other beat. |
Unifocal PVCs | Look exactly the same - probably came from the same site in the ventricles. |
Trigeminal PVCs | Every third beat |
Quadrigeminal PVCs | Every fourth beat |
Couplet PVCs | Paired |
Multifocal PVCs | When PVCs look different. |
R-on-T Phenomenon | When a PVC has occurred during the vulnerable period of ventricular repolarization (on/near peak of T wave). May precipitate into VT or VF! |
monomorphic VT | when QRS complexes are identical |
polymorphic VT | when QRS complexes look different |
Treatment of stable monomorphic VT with a pulse | * amiodorone 150mg IV bolus/10min, followed by 1mg/min infusion over 6hrs then 0.5mg/min over 18hrs. * lidocaine 1-1.5mg/kg IV bolus, then 0.5-0.75mg/kg IV q5-10min. Maintenance: 1-4mg/min. * AL drugs - ^ |
torsades de pointes | * polymorphic VT * pt becomes hemodynamically unstable very quickly |
treating torsades de pointes | * remove/correct the causative factors. * Mg loading dose 1-2g/10mL dextrose 5% in water over 5min followed by maintenance infusion of 0.5-1g/hour. |
ventricular standstill | * P waves w/o QRS complexes or an isoelectric line. May occur d/t acidosis, hypoxia, hyperkalemia, hypothermia or drug OD. |
atrial kick accounts for ___ of CO. | 30% |
Closure of the AV valves constitutes which heart sound? | S1. AV = mitral and tricuspid |
Closure of the pulmonic valves constitutes which heart sound? | S2. PV = semilunar valves. aortic and pulmonic |
P wave | * atrial depolarization * smooth and rounded * 1P:1QRS * + in lead II * abnormally tall, peaked P = enlargement of R atrium |
PR interval | * represents the time from the onset of atrial depolarization to the time of ventricular depolarzation * 0.12-0.20sec |
QRS complex | * ventricular depolarization * 0.06-0.10sec |
ST segment | * represents end of ventricular depolarization and the beginning of ventricular repolarization * Normally isoelectric * elevation = ominous, MI * depression = myocardial ischemia * scooped out appearance w/ digitalis |
T wave | * ventricular repolarization |
1 small box on EKG paper = ____sec | 0.04 |
5 small boxes on EKG paper = ____sec | 0.20 |
2 black lines = _____sec. a typical strip is _____sec. | 3, 6. |