ECG tracings
electrophysiology study (EPS)
procedure used to identify the cause/site of life-threatening cardiac arrhythmias by mapping the heart's conduction system in a patient with an arrhythmia
when to defibrillate
pulseless VT, VF, arrest
Second Degree Heart Block Type I (Wenckebach)
PR interval gradually lengthens as AV conduction time increases until a QRS is dropped. P-P is constant. Atrial rate is greater than ventricular rate. R-R is irregular. - usually a result of an MI or a warning sign of more serious AV disturbance (like a type 3)
3rd Degree Heart Block (Complete Heart Block)
- Impulses are completely disassociated - QRS & P-waves (atrial rate 60-100) seen, but irregular w/ no correlation btwn the two - Ventricular rate is slow and this impairs cardiac output. Can progress to ventricular standstill - complications: SCD
SVT treatment
- Mild (P150s-170, BP stable): vasovagal maneuver - Moderate (P170s-190+ BP unstable/SBP90): Adenosine given in antecubital vein nearest to heart on a 3-way stop cock w/ 20 ml flush immediately after - Severe (P190-230+, hypotensive/SBP<90): synchronized cardioversion
Symptoms & tx of Afib
- SX: SOB, palpitations, irregular pulses TX: goal is to decrease the ventricular response, prevent stroke, and convert to sinus rhythm - anticoags if >48hrs - antidysrhythmics to control ventricular rate (Cardizem, Amiodarone, Digoxin) - cardiovert if <48hrs w/ amiodarone - synchronized cardioversion w/ 50-100 joules, pt must be sedated - radiofrequency ablation if meds unsuccessful
Causes & clinical significance of v-fib
- VT deteriorates into VF within 3 mins - seen w/ myocardial ischemia, bradycardia, metabolic abnormalities, antidysrhythmic drugs, digoxin
Atrial Flutter Treatment
- anticoagulants if >48hrs - antidysrhythmics - CCB and b-blockers if <48hrs - electrocardioversion if unstable & <48hrs - may need radiofrequency catheter ablation
Adenosine ECG changes
- asystole may be seen following the administration of adenosine
Atrial Fibrillation
- disorganized atrial electrical activity (350-600 bpm) - ventricles either normal or in RVR (>100) - normal rhythmic atrial contractions are replaced by rapid irregular twitching of the muscular heart wall - associated w/ CAD, valvular dz, myopathy, HTN, HF, thyroid storm, EtOH toxicity, caffeine, stress) - results in decreased CO from ineffective atrial contraction & clots form causing stroke, MI, PE, & DVT
TX if Wenckebach
- if symptomatic, atropine can be used to increase HR & placed on temorary pacemaker - if asymptomatic, keep a transcutaneous pacer nearby
Cardioversion considerations
- pt w/ a-fib of unknown duration (>48hrs) must receive adequate anticoagulation for 4-6 wks prior to prevent thrombi dislodgement - hold digoxin 48hrs prior
Sinus Tachycardia
-HR 100-180 bpm -Normal equal P and QRS in all the leads, as well as normal PR intervals
Heart Block Poem
-If the R is far from the P then you have a first degree -Longer, longer, longer drop then you have a Wenkebach -if some Ps don't get through then you have a Mobitz II -If Ps and Qs don't agree then you have a third degree
1 small box
0.04 sec (40 ms) lateral/time 0.1mv vertical/amplitude
Normal QRS interval
0.06 - 0.1 sec (generally <.2 sec) 1 - 3 small boxes
Normal PR interval
0.12-0.20 seconds
1 large box
0.2 sec (200ms) 0.5 mv
Normal QT interval
0.34-0.44 represents time between electrical depolarization and repolarization of ventricles - as HR ↑, QT interval ↓
Paroxysmal Supraventricular Tachycardia (PSVT)
A dysrhythmia originating in an ectopic focus anywhere above the bifurcation of the bundle of His. starts & ends suddenly - P wave is often hidden in the preceding T wave, but if seen may have an abnormal shape. - The PR interval may be shortened or normal, and QRS is usually normal.
R on T phenomenon
A premature ventricular QRS complex in the ECG interrupting the T wave of the preceding beat; often predisposes to serious ventricular arrhythmias .
Ventricular tachycardia (VT)
A rapid heart rhythm in which the electrical impulse begins in the ventricle (instead of the atrium), which may result in inadequate blood flow and eventually deteriorate into cardiac arrest. - rate 150-250 bpm - exists when 3 or more PVCs occur in a row - may occurs w/ or without pulses
Sinus Arrhythmia
A sinus rhythm in which the rate varies with respiration, causing an irregular rhythm, HR increases slightly w/ inspiration & decreases w/ expiration. - remains 60-100 bpm
Torsades de pointes
A type of ventricular tachycardia in which depolarization impulses move from one ventricle to the other, resulting in a "twisted ribbon" appearance on the ECG tracing
Tx of monomorphic VT
Amiodarone IV
radiofrequency catheter ablation
An invasive procedure that uses radiofrequency waves to abolish an irritable focus that is causing a supraventricular or ventricular tachydysrhythmia.
Tx of Asystole
CPR and Epi This will NOT be defibrillated.
Premature Atrial Contraction
Contraction originating from ectopic focus in atrium in location other than SA node causing an early contraction - pt describes the feeling as palpitations or "heart skipped a beat"
Sinus Bradycardia
HR is less than 60 beats/min and rhythm is regular. - The P wave precedes each QRS complex and has a normal shape and duration. - The PR interval is normal. - The QRS complex has a normal shape and duration.
causes of PVCs
Hypokalemia, hypomagnesemia, excess caffeine, chemical imbalance, illegal drugs, alcohol.
Tx of polymorphic VT
IV phenytoin or IV Magnesium
TX of v-fib
Immediate defibrillation, CPR, intubation, ACLS, and medications (epi & amiodarone)
Polymorphic Ventricular Tachycardia
Occurs when the QRS complexes arise from multiple ectopic sites and gradually change back and forth from one shape, size, and direction to another over a series of beats.
Monomorphic Ventricular Tachycardia
QRS complexes that arise from the same ectopic site and are the same shape, size, and direction.
Atrial flutter
Rate:Atrial 250-350 Ventricular: 100 -175 P-wave: Irregular or absent, often "saw tooth" QRS: Normal Conduction: AV Block (2:1 > 3:1, 4:1) Rhythm: Regular (usually) - Often d/t underlying cardiac disease (CAD, HTN, valve disorder, lung dz, myopathy, hyperthyroid) - Results in CO and HF w/ increased risk of clotting
Tx of complete heart block
Requires emergency treatment. - temporary pacemaker used as bridge to permanent pacemaker. Atropine is NOT effective
First degree heart block
Slowed conduction through the AV node. PR interval prolonged (>0.20). Not life threatening. - normal HR & rhythm, normal P wave and QRS complex
Second Degree Heart Block
Some P waves are not conducted through the AV node; hence more P than QRS waves are seen. Dropped p waves are not preceded by prolonged PR. The ratio of P waves to QRS waves can be 2:1, 3:1 etc. - This AV block is more serious because more of the SA node impulses are not conducted to the ventricles and this is associated with rheumatic heart dx, CAD, anterior MI, & drug toxicity. Can progress into 3rd degree heart block
Asystole
Total absence of cardiac activity (Flat line).- no ventricular rate or rhythm, no pulse, no CO. - may occur d/t extensive myocardial damage, hypoxia, K+ imbalance, hypothermia, acidosis, OD, ARF.
Tx of Mobitz type I
Transcutaneous pacing until permanent pacer is placed. Atropine does NOT work
Couplet PVC
Two PVC's occurring together without any pause in between
Ventricular fibrillation (V-fib)
Uncoordinated depolarization of ventricles causing an irregularly irregular rate. Ventricles quiver, resulting in ineffective contraction -> no pulse or CO. - pt is unresponsive, apneic & pulseless • fine waves <3mm • coarse waves >3mm
Causes of PACs
Usually harmless -Excessive caffeine, alcohol, or tobacco, lack of sleep, medications -Myocardial ischemia or injury -Hypokalemia -Digitalis toxicity -CHF, COPD
When to use defibrillation
V-fib or pulseless VT
Pulseless Electrical Activity (PEA)
a condition in which the heart's electrical rhythm remains relatively normal, yet the mechanical pumping activity fails to follow the electrical activity, causing cardiac arrest
P-wave asystole
asystole with only p waves
1 mv
equal to 2 large squares on EKG grid, 10 mm high
Bigeminy PVC
every other beat is a PVC
Trigeminy PVC
every third beat is a PVC
Three or more consecutive PVCs
indicate Vtach
Premature Atrial Contraction (PAC)
irregular heart rhythm characterized by atrial contractions occurring before the expected time
Normal sinus rhythm (NSR)
regular rhythm of the heart cycle stimulated by the SA node (average rate of 60-100 beats/minute) - The P wave is normal, precedes each QRS complex, and has a normal shape and duration. - The PR interval is normal. The QRS complex has a normal shape and duration
sustained vs nonsustained vtach
sustained: lasts >30 seconds unsustained: last <30 sec
Premature Ventricular Contraction
ventricular contraction that occurs early and independently in the cardiac cycle before the sinoatrial node initiates an electrical impulse. -Early QRS with no P wave (large!), usually opposite the polarity of normal QRSs
When to use cardioversion
when a pt is unstable in VTw/pulse, PSVT, AFIB or AFlutter
