MORE DETAILED ARRYHTHMIAS Flashcards
What are the different causes of Arrhythmias?
1) Abnormal rhythmicity of the pacemaker2) Shift of pacemaker activity3) Conduction Blocks4) Abnormal pathways of impulse transmission5) Spontaneous generation of abnormal impulses
7 Questions that must be asked to determine whether or not arrythmias are present
1) What is the heart rate?2) What is the rhythm?3) Are P waves present?4) Is there a P wave for every QRS complex?5) Is there a QRS for every P?6) Are the P’s and QRS’s consistantly related?7) Do all the P’s and QRS’s look alike?
3 Different Types of Normal Cardiac Rhythms
1) Normal Sinus Rhythm2) Sinus Arrhythmia3) Wandering Atrial PacemakerLook at Lead 2 (60 Degrees)
What Arrhythmias produce different speeds of heart rate?
Sinus BrachycardiaSinus Tachycardia
Sinus arrhythmia
Impulses originate at the SA node at a varying rate = fires FASTER and then SLOWERAll complexes are normal butRHYTHMICALLY IRREGULARLongest PP or RR interval exceeds shortest by 0.16 sec or moreCAUSED BY HEAVY RESPIRATION
Wandering atrial pacemaker
Impulses originate from varying points in atria between SA and AV nodesP Wave changes configuration as signal begins at different areasQRS is NORMAL
Sinus Brachycardia
Impulses originate at SA Node at a SLOW rateNormal sinus rhythm w/ HR Parasympathetic Causes - increased vagal tone, beta-blockers, propanolol, digitalis
Sinus Tachycardia
Impulses originate at the SA Node at a RAPID rateNormal sinus rhythm w/ HR > 160 bpmSympathetic Causes = exercise, fever, hyperthyroidism, shock, etc.
Sinus arrest
Abnormal ArrhythmiaSA node stops firing (beats with a pause = NORMAL PACING WITH A BASELINE PAUSEEscape Beat = first large upward deflection after pause
A dog faints due to loss of blood to the brain. What would be the compensatory effect to help blood get to brain since blood is not fighting gravity?
Sinus Arrest
Abnormal Rythms that result from Impulse Conduction Blocks
1) 1st Degree Atrioventricular Block2) 2nd Degree AV Block3) 3rd Degree AV BlockCauses of AV Blocks include: ischemia of AV node, compression or inflammation of AV node/Bundle, and increased stimulation of heart by vagus nerve
First degree AV block
Abnormal rhythm that results from Impulse Conduction Blocks (potential wide P Wave)Fixed but PROLONGED PR INTERVALPartial block above OR below AV NodePotential Causes = Mitral insufficiency, Digoxin toxicityNot dangerous but will progress
Second degree AV block
Abnormal rhythm that results from Impulse Conduction Blocks2 Different Types:1) Mobitz Type I - PROGRESSIVE LENGTHENINGof PR interval before dropped beatCoduction starts off normal but gets progressively work with accompanied lengthening B4 dropped QRS= AV node recovers and PR Interval is normal againWenckbach PhenomenomPotential Causes = Digoxin Toxicity2) Mobitz Type II - SUDDENQRS dropped W/OUT prior PR IntervallengtheningAV Block at level of Bundle of His ORat bilateral bundle branches OR at trifascicularAtrial rate is greater than the ventricular rate (MOREP waves due to QRS drop)Non-WenkebachCan have MULTIPLEP waves without a QRS Complex
Third degree AV block
Abnormal rhythm that results from Impulse Conduction BlocksCOMPLETE AV BLOCKNO RELATIONSHIP BETWEEN P WAVES AND QRS COMPLEXES2 different scenarios - SA Node conducts impulse in atria (P waves)BUT:1) Block ABOVE AV Node= AV Node conducts impulses to ventricles2) Block BELOW AV Node = Purkinje Fibers conduct impulse to ventriclesAtria and Ventricles fire a DFFERENT ratesQRS rate is SLOWERthan the P rate bc AV node and Purkinje fibers fire at slower rates than the SA NodePacemake placed in ventricles to allow P waveand QRS complexe rates to match up
Supraventricular (ABOVE) and Ventricular Abnormalities
Different Types:1) Premature Contraction:2) Tachycardia3) Fibrillations
Premature Contraction (Supraventricular and Ventricular Abnormalities)
Produces PULSE DEFECIT = ventricle DO NOT fill with blood properly = stroke volume is DECREASED or ABSENTBIGEMINAL PULSE = Every other beat may be prematureMost caused by ectopic foci (pacemakers) from ischemia, calcified plaques, toxic irritation of different areas of the heart due to drugs
Tachycardia (Supraventricular and Ventricular Abnormalities)
Atleast 3 or more PREMATURE CONTRACTIONSPAROXYSMAL - last for seconds, minutes, hours, or longer and stop as quickly as they start
Fibrillations (Supraventricular and Ventricular Abnormalities)
Many separate and small waves spreading at the same time in DIFFERENT DIRECTIONS over the cardiac muscle
Supraventricular premature contraction
Premature beatsP occurs before T wave of preceding complex = P-Q-R-S-P-TMorphology of beats look SIMILAR to sinus beatsDuration of QRS complexes are NORMALProduces ATRIAL PREMATURE COMPLEXESCan produce PULSE DEFECIT andBIGEMINAL PULSE
AtrialParoxysmal Tachycardia
Occurs as PAROXYSMS (bursts)Inc in heart rateInverted P wave the is superimposed on T wave before every QRS ComplexABNORMAL SHAPE OF P WAVE
Atrial flutter
Supreventricular Paroxysmal TachycardiaImpulses travel CIRCULAR COURSE in atria = regular, rapid FLUTTER WAVES (F) w/ NO isoelectric baselineProduces VARIABLE BLOCK (3rd Degree Heart BlockAtria contracting quicklyQRS can be regular, irregular, or slower depending on blockPossible Cause = DigoxinLOTS OF LITTLE ROUNDED WAVES BETWEEN Q AND Q
Atrial Fibrillation
Supreventricular Paroxysmal TachycardiaDisorganized electrical impuses from atria = irregular ventricular rhythmIt produces NO DISTINCTP waves (due to NO ATRIAL CONTACTION) = BASELINE UNDULATIONS insteadQRS looks normal BUT are IRREGULARLY SPACEDSA Node fire but no contraction due to chaotic signalSimilar to atrial flutter when looking at ECG2 types = Course (larger deflections) and Fine (smaller deflections)LOTS OF LITTLE WAVES BETWEEN Q AND Q
Ventricular premature contraction
Due to ectopic focus (PACEMAKER) in Ventricular myocardiumCauses WIDE AND BIZARREQRS complexes (usually NO P wave present)One ventricle contract before the otherT wave = opposite deflection of QRS complexMULTIPLE ectopic foci/pacemakers = VARYING MORPHOLOGY of QRS complexes MULTI-FORM VPC:1) Ventricular Bigeminy2) Ventricular Paroxysmal Tachycardia
Ventricular bigeminy
Ventricular Premature Contraction that occurs every other beatnormal—->premature—->normal—->prematureDue to ectopic focus (pacemaker)
Ventricular Paroxysmal Tachycardia
runs of 3 or more VENTRICULAR PREMATURE CONTRACTIONSin SEQUENCEDue to ectopic focus (pacemaker)Serious condition bc typically due to ischemic damage of ventricles AND can initiate VENTRICULAR FIBRILLATION
Ventricular fibrillation
Chaotic ventricular depolarizationDue to ectopic foci (pacemakers) with in Twave or in vulnerable period (ventricular depolarization)MOST SERIOUS OF ALL CARDIAC ARRHYTHMIASProduces = no QRS waves, no cardiac output = Death in a few min2 Types = Course (larger deflections) and Fine (smaller deflections)LOTS OF DEFLECTIONS IN A ROW = CRAZY TRACINGCauses = electrical shock, ischemiaVULNERABLE PERIOD = during ventricular repolarization bc somareas are in refractory period and others aren’t = single electric shock = fibrillation
Intraventricular conduction defects
impulses aren’t as fast, QRS duration will be longer
Left bundle branch block
wide and positive deflections in I, II, III, aVF, and inverted aVR and aVL, large R waves
Right bundle branch block
right axis deviation usually present, large S waves in I, II, III, aVF
Supraventricular paroxysmal tachycardia
clusters of premature contractions
Sinatrial Block
Block at SA NodeNo P wavesAV Node produces impulse in ventricles = QRS waves
Supraventricular Paroxysmal Tachycardia
1) Atrial Paroxysmal Tachycardia2) AV Node Paroxysmal Tachycardia
AV Node Paroxysmal Tachycardia
Aberrant rhythm in AV node = abnormal QRS Waves and NO P Waves
Phenomenon of Re-entry
Causing abnormal contraction that disturbs normal pace settingCan occur due to 3 different reasons:1) heart is dilated lengthening the pathway the impulsehas to take to cause conduction throughout the heart = so when it returns the muscles are no longer in their normal refractory period2) Blockage of Purkinje system, ischemia of the heart, high blood potassium levels, etc. cause decreased of velocity of the impulse causing the same consequence3) Various drugs cause shortened refractory period of cardiac muscles = same consequence
Electrical Shock Defibrillation of the Ventricles
Strong electrical current passed through the heart for a short interval throws ALL muscle into refractoriness simultaneouslyBC all impulses STOP = pacemaker and regain control of the heart
