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Flashcards in PHYSIOLOGY - ARRYTHMIAS Deck (35)
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1

What are the different causes of Arrhythmias?

1) Abnormal rhythmicity of the pacemaker

2) Shift of pacemaker activity

3) Conduction Blocks

4) Abnormal pathways of impulse transmission

5) Spontaneous generation of abnormal impulses

2

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

3 Different Types of Normal Cardiac Rhythms

1) Normal Sinus Rhythm 2) Sinus Arrhythmia 3) Wandering Atrial Pacemaker Look at Lead 2 (60 Degrees)

4

What Arrhythmias produce different speeds of heart rate?

Sinus Brachycardia

Sinus Tachycardia

5

Sinus arrhythmia

Impulses originate at the SA node at a varying rate = fires FASTER and then SLOWER

All complexes are normal but RHYTHMICALLY IRREGULAR

Longest PP or RR interval exceeds shortest by 0.16 sec or more

CAUSED BY HEAVY RESPIRATION

6

Wandering atrial pacemaker

Impulses originate from varying points in atria between SA and AV nodes

P Wave changes configuration as signal begins at different areas

QRS is NORMAL

7

Sinus Brachycardia

Impulses originate at SA Node at a SLOW rate

Normal sinus rhythm w/ HR

Parasympathetic Causes - increased vagal tone, beta-blockers, propanolol, digitalis

8

Sinus Tachycardia

Impulses originate at the SA Node at a RAPID rate

Normal sinus rhythm w/ HR > 160 bpm 

Sympathetic Causes = exercise, fever, hyperthyroidism, shock, etc.

9

Sinus arrest

Abnormal Arrhythmia

 

SA node stops firing (beats with a pause = NORMAL PACING WITH A BASELINE PAUSE

Escape Beat = first large upward deflection after pause

10

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

11

Abnormal Rythms that result from Impulse Conduction Blocks

1) 1st Degree Atrioventricular Block

2) 2nd Degree AV Block

3) 3rd Degree AV Block

 

Causes of AV Blocks include: ischemia of AV node, compression or inflammation of AV node/Bundle, and increased stimulation of heart by vagus nerve

12

First degree AV block

Abnormal rhythm that results from Impulse Conduction Blocks (potential wide P Wave)

Fixed but PROLONGED PR INTERVAL

Partial block above OR below AV Node

Potential Causes = Mitral insufficiency, Digoxin toxicity

Not dangerous but will progress

13

Second degree AV block

Abnormal rhythm that results from Impulse Conduction Blocks

2 Different Types:

 

1) Mobitz Type I - PROGRESSIVE LENGTHENING of PR interval before dropped beat

Coduction starts off normal but gets progressively work with accompanied lengthening B4 dropped QRS = AV node recovers and PR Interval is normal again

Wenckbach Phenomenom 

Potential Causes = Digoxin Toxicity

 

2) Mobitz Type II - SUDDEN QRS dropped W/OUT prior PR Interval lengthening

AV Block at level of Bundle of His OR at bilateral bundle branches OR at trifascicular

 Atrial rate is greater than the ventricular rate (MORE P waves due to QRS drop)

Non-Wenkebach 

 

Can have MULTIPLE P waves without a QRS Complex

14

Third degree AV block

Abnormal rhythm that results from Impulse Conduction Blocks

COMPLETE AV BLOCK

NO RELATIONSHIP BETWEEN P WAVES AND QRS COMPLEXES

 

2 different scenarios -  SA Node conducts impulse in atria (P waves) BUT:

1) Block ABOVE AV Node = AV Node conducts impulses to ventricles

2) Block BELOW AV Node = Purkinje Fibers conduct impulse to ventricles

 

Atria and Ventricles fire a DFFERENT rates

QRS rate is SLOWER than the P rate bc AV node and Purkinje fibers fire at slower rates than the SA Node

Pacemake placed in ventricles to allow P wave and QRS complexe rates to match up

15

Supraventricular (ABOVE) and Ventricular Abnormalities

Different Types:

1) Premature Contraction:

2) Tachycardia

3) Fibrillations

16

Premature Contraction (Supraventricular and Ventricular Abnormalities)

Produces PULSE DEFECIT = ventricle DO NOT fill with blood properly = stroke volume is DECREASED or ABSENT

BIGEMINAL PULSE = Every other beat may be premature

Most caused by ectopic foci (pacemakers) from ischemia, calcified plaques, toxic irritation of different areas of the heart due to drugs

17

Tachycardia (Supraventricular and Ventricular Abnormalities)

Atleast 3 or more PREMATURE CONTRACTIONS

PAROXYSMAL - last for seconds, minutes, hours, or longer and stop as quickly as they start

18

Fibrillations (Supraventricular and Ventricular Abnormalities)

Many separate and small waves spreading at the same time in DIFFERENT DIRECTIONS over the cardiac muscle

19

Supraventricular premature contraction

Premature beats

P occurs before T wave of preceding complex = P-Q-R-S-P-T

Morphology of beats look SIMILAR to sinus beats

Duration of QRS complexes are NORMAL

Produces ATRIAL PREMATURE COMPLEXES

 

Can produce PULSE DEFECIT and BIGEMINAL PULSE

 

20

Atrial Paroxysmal Tachycardia

Occurs as PAROXYSMS (bursts)

Inc in heart rate

Inverted P wave the is superimposed on T wave before every QRS Complex

ABNORMAL SHAPE OF P WAVE

 

 

21

Atrial flutter

Supreventricular Paroxysmal Tachycardia

Impulses travel CIRCULAR COURSE in atria = regular, rapid FLUTTER WAVES (F) w/ NO isoelectric baseline

Produces VARIABLE BLOCK (3rd Degree Heart Block

Atria contracting quickly

QRS can be regular, irregular, or slower depending on block

Possible Cause = Digoxin

LOTS OF LITTLE ROUNDED WAVES BETWEEN Q AND Q

22

Atrial Fibrillation

Supreventricular Paroxysmal Tachycardia

Disorganized electrical impuses from atria = irregular ventricular rhythm

 

It produces NO DISTINCT P waves (due to NO ATRIAL CONTACTION) = BASELINE UNDULATIONS instead

QRS looks normal BUT are IRREGULARLY SPACED

SA Node fire but no contraction due to chaotic signal 

Similar to atrial flutter when looking at ECG

2 types = Course (larger deflections) and Fine (smaller deflections)

 

LOTS OF LITTLE WAVES BETWEEN Q AND Q

 

23

Ventricular premature contraction

Due to ectopic focus (PACEMAKER) in Ventricular myocardium

Causes WIDE AND BIZARRE QRS complexes (usually NO P wave present)

One ventricle contract before the other

T wave = opposite deflection of QRS complex

MULTIPLE ectopic foci/pacemakers = VARYING MORPHOLOGY of QRS complexes MULTI-FORM VPC:

1) Ventricular Bigeminy

2) Ventricular Paroxysmal Tachycardia

 

24

Ventricular bigeminy

Ventricular Premature Contraction that occurs every other beat

normal---->premature---->normal---->premature

Due to ectopic focus (pacemaker)

25

Ventricular Paroxysmal Tachycardia

runs of 3 or more VENTRICULAR PREMATURE CONTRACTIONS in SEQUENCE

Due to ectopic focus (pacemaker)

Serious condition bc typically due to ischemic damage of ventricles AND can initiate VENTRICULAR FIBRILLATION

26

Ventricular fibrillation

Chaotic ventricular depolarization

Due to ectopic foci (pacemakers) with in Twave or in vulnerable period (ventricular depolarization)

MOST SERIOUS OF ALL CARDIAC ARRHYTHMIAS

Produces = no QRS waves, no cardiac output = Death in a few min

2 Types = Course (larger deflections) and Fine (smaller deflections)

LOTS OF DEFLECTIONS IN A ROW = CRAZY TRACING

Causes = electrical shock, ischemia

VULNERABLE PERIOD = during ventricular repolarization bc somareas are in refractory period and others aren't = single electric shock = fibrillation

27

Intraventricular conduction defects

impulses aren't as fast, QRS duration will be longer

28

Left bundle branch block

wide and positive deflections in I, II, III, aVF, and inverted aVR and aVL, large R waves

29

Right bundle branch block

right axis deviation usually present, large S waves in I, II, III, aVF

30

Supraventricular paroxysmal tachycardia

clusters of premature contractions

31

Sinatrial Block

Block at SA Node

No P waves

AV Node produces impulse in ventricles = QRS waves

32

Supraventricular Paroxysmal Tachycardia

1) Atrial Paroxysmal Tachycardia

2) AV Node Paroxysmal Tachycardia

33

AV Node Paroxysmal Tachycardia

Aberrant rhythm in AV node = abnormal QRS Waves and NO P Waves

34

Phenomenon of Re-entry

 

Causing abnormal contraction that disturbs normal pace setting

Can occur due to 3 different reasons:

1) heart is dilated lengthening the pathway the impulse has to take to cause conduction throughout the heart = so when it returns the muscles are no longer in their normal refractory period

2) Blockage of Purkinje system, ischemia of the heart, high blood potassium levels, etc. cause decreased of velocity of the impulse causing the same consequence

3) Various drugs cause shortened refractory period of cardiac muscles = same consequence 

35

Electrical Shock Defibrillation of the Ventricles

Strong electrical current passed through the heart for a short interval throws ALL muscle into refractoriness simultaneously

BC all impulses STOP = pacemaker and regain control of the heart