Ekg Test 2 Flashcards
Major cellular properties that distinguish cardiac cells from other tissues are their
- Contractility
- Conductivity
- Automaticity
- Rythmicity
Conduction Systems
- SA node
- AV node
- bundle of his
- purkinjie fibers
Contractility
Cardiac tissue can contract in response to electrical stimuli
Conductivity
Myocardial cells conduct electricity after stimulation
Automaticity
Ability to initiate its own beats
Rythmicity
Capability if maintaining regularity of such pace making activity
Bipolar leads
Basic leads proposed by William Einthoven was the Nobel Prize winner in 1924 for invention of practical electrocardiogram
He says the sum of heights of QRS in leads I and lll equals the height of QRS in lead II it’s called Einthovens law
Normal sinus rhythm
Impulse originate in SA node to AV node to ventricles through normal pathways resulting in a normal P and QRS complex
rate- 60-100 bpm
Sinus Arrhythmia
The heart rate stays within normal limits however the rhythm will be irregular.
It will have waxing and waning on heart rate in response to respiration
It’s the result of vagal control
Commonly seen in athletes, children, patients with sleep apnea
Rate- increases on inspiration decreases with expiration
There’s no treatment I
Sinus Bradycardia
Characterized by sinus rhythm heart rate below 60bpm
Clinical significance- Can result in hemodynamic compromise and symptoms such as : syncope,chest pain, premature beats, ventricular tachycardia
No treatment is needs if patient is asymptomatic and rate stays close to 60 bpm. If patient becomes symptomatic administer Atropine
Sinus tachycardia
Involves accelerated firing of SA node with a rate greater than 100 bpm
Clinical significance - Considered symptom of an underlying pathophysiologic process should find primary cause rather than treating it right away
Pharmacologic agents like beta blockers, calcium channel blockers, adenosine, or digoxin any be helpful
Sinus Arrest
Normal sinus rhythm is interrupted by prolonged failure of SA node to initiate an impulse resulting on complete missing of PQRST complex
Rate- usually normal limits however length and frequency pauses may lead to bradycardia
Treatment same as sinus bradycardia administer Atropine
Etiology- ischemia affecting SA node, effect of SA nodal blocking drugs ex. Beta blockers and excessive vagal tone
Premature Atrial Complexes (PAC)
Rate- usually within normal limits
Clinical significance -Occasional PACs are benign. Once become more frequent may cause subjective symptoms such as palpitations.
However frequent PACs sometimes prelude to atrial tachycardia of fibrillation.
Treatment - Recurrent PACs can be treated with digitalis
First Degree Heart Block
Characterized by- elongated PR interval. It’s longer stretches everything out
Clinical significance- it’s benign. Causes by coronary artery disease causing AV nodal ischemia
Treatment - beta blockers, calcium channel , blockers, and digoxin
Second Degree Heart Block (Wenckebach)
Periodic conduction failure within AV node causing PR interval to lengthen until a drop in QRS complex. After this dropped beat cycle repeats forming groups of beats called footprint of Wenckebach
clinical significance - has same causative factors as first degree heart block
Treatment- asymptomatic however symptomatic patients may need transcutaneous or transvenous pacing
Mobitz Type II
More serious then Wenckebach. Location of block can be either AV node or bundle of branch level
Characteristics - regular rhythm with constant PR interval from beat to beat than sudden drop of QRS complex
Clinical significance- left untreated can progress into serious AV dissociation. Usually causes by hypoxia,myocardial infarction,conduction system disturbance
Treatment - Epinephrine
Ventricular Fibrillation
Disorganized and chaotic ventricular rhythm has hemodynamic implications.
Completely irregular with fibrillatory waves
The only shockable rhythm
Clinical significance - does not generate cardiac output advanced life support measures and emergent defibrillation needed
Treatment - Amiodarone and Lidocaine
Asystole
Ventricular standstill no cardiac output
Flat line appears means no pacemaker activity happening anywhere in the heart.
Clinical significance -terminal rhythm of the heart , seen after profound cardiac damage,severe hypoxia , multisystem failure
Treatment- aggressive resuscitative efforts with Epinephrine, Atropine, and CPR
Corse V Fib
Does not generate cardiac output immediate basic and advanced life support and AED needed.
Treatment- Amiodarone and Lidocaine
Clinical Significance - causative factors same as that of ventricular tachycardia
Torsadea de Pointes (TDP)
French term means - twisting of the points
Rate- 150-300 bpm
Ventricular tachycardia with a varying QRS morphology. May be produced by acute ischemia, myocarditis
Clinical significance- lethal arrhythmias can degrade into v fib
Treatment- intravenous administration of magnesium
Monomorphic VT
Treated with immediate asynchronous DC cardioversion.
Intravenous Lidocaine or Amiodarone
Agonal Rhythm
Worst possible cardiac rhythm second to asystole. Impending death
Rate - less than 20 bpm
Irregular occasional wide complex beats
