ECG's

Block in Bundle of His QRS widened Heart rate 20-40; ventricles pacing

3 degree AV Block @ Block in Bundle of His

Junctional foci spared QRS complexes still narrow Heart rate okay at 40-60; junction pacing

3 degree AV Block @ junctional foci spared

Block below Bundle of His QRS widened Heart rate 20-40; ventricular foci pacing Often caused by complete Bundle Branch Block

3 degree AV Block @Block below Bundle of His

AV Node conduction

Identify the blue box

Atrial contraction or P wave

Identify the blue box

Isovolumetric Contraction or QRS complex

Identify the blue box

SA Node (nothing)

Identify the blue box

Ventricular contraction or ST segment

Identify the blue box

Ventricular relaxation or T wave

Identify the blue box

the inverted p wave will be after the QRS complex

If the junctional rhythm originates in the low of the atria AV node what does the P wave look like?

it will not be seen, will be hidden by the QRS - contracted at the same time as the ventricles

If the junctional rhythm originates in the middle of the atria AV node what does the P wave look like?

inverted, upside down, flipped

If the junctional rhythm originates in the top AV node (toward the SA node) of the atria what does the P wave look like?

Instead of a pause, like in an escape rhythm, premature beats come too early (close to the previous QRS complex) Irritable focus fires a single stimulus, "IMPATIENT"

What are premature beats (Ectopy) or premature contractions?

saw tooth, repeating P wave

What are you looking for in a atrial flutter?

The SA node

What area of the heart contains the greatest concentration of pacemaker cells?

Q = initial downward deflection (often absent)

What is "Q" ?

R= first upward deflection

What is "R"?

S = ANY downward wave preceded by an upward wave

What is "S"

-These are simply two different patterns of premature beats -You can have these patterns in atrial, junctional, or ventricular beats -BIGEMINY: Every normal cycle (P wave, QRS, T wave) is followed by a premature beat, 1:1 -TRIGEMINY: Every TWO normal cycles are followed by a premature beat, 2:1

What is Bigeminy and Trigeminy?

SVT is a blanket statement for any narrow QRS complex tachycardia in which the P waves are not obvious. The most important learning point regarding SVT is that it is not one rhythm, but rather a classification that encompasses many rhythms. The term is used to differentiate these tachycardias from ventricular tachycardia which is a wide QRS tachycardic rhythm

What is a SVT?

First degree: prolonged PRI (constant), no dropped beats

What is a first degree heart block?

Second degree: Mobitz I: PRI gets successively longer with each beat then drops a beat (going, going, gone) Mobitz II: PRI is constant (may be prolonged but does not have to be) then drops a beat

What is a second degree heart block?

Third degree: Atria and ventricles are not communicating (firing separately) - each "to its own drummer"

What is a third degree heart block?

An escape pacemaker is a pacemaker site other than the SA node. For example, the AV node is an escape pacemaker. If the SA node fails to fire, the escape pacemaker sites serve as a fail-safe mechanism to make sure another site steps in and assumes pacing responsibility.

What is an escape pacemaker ?

A basic beat

What is pictured?

P wave PR interval QRS complex Q = initial downward deflection (often absent) R = first upward deflection S = ANY downward wave preceded by an upward wave ST segment T wave Isoelectric line - flat, straight line; indicates no electrical activity

What is seen on a ECG?

Isoelctric line

What is the blue box pointing to?

Positive deflection

What is the blue box pointing to?

negative deflection

What is the blue box pointing to?

Receives impulse from SA node; delays relay of impulse to allow ventricular filling

What is the function of the AV node?

Primary pacemaker; initiates impulse that is normally conducted through atria

What is the function of the SA node?

DECREASES - heart rate, conduction velocity, and irritability

What is the general role of the CNS - parasympathetic system?

INCREASES - heart rate, conduction velocity, and irritability

What is the general role of the CNS - sympathetic system?

40 -60 BPM

What is the heart rate of the AV junction?

20 - 40 BPM

What is the heart rate of the Purkinje Fibers?

60 - 100 BPM

What is the heart rate of the SA node?

Wenckebach

What is the other name for Mobitz I?

The SA node is normally the primary pacemaker of the heart because it has the fastest firing rate of all of the heart's normal pacemaker sites

What is the primary pacemaker of the heart? And why?

This property is known as automaticity.

What is the property that allows heart cells to act as pacemakers?

A normal heart beat follows this sequence: SA node generates an electrical current This current travels through the atria The current then enters the AV node, where it slows The current enters the ventricular conduction pathway where it travels rapidly Ventricles contract Ventricles relax The SA node is the area of the heart that contains the greatest concentration of pacemaker cells

What is the sequence of the normal heart beat?

40 - 45 BPM

What is the specific heart rate for the Bundle Branch?

40 -45 B

What is the specific heart rate for the bundle of HIS?

45 - 50 BPM

What is the specific heart rate of the AV Node?

35 - 40 BPM

What is the specific rate for purkinje cells?

Vagus nerve

What parasympathetic nerve is triggered?

The SA node fails to fire The SA node fires too slowly The SA node fails to activate the surrounding atrial myocardium

When do other areas of the heart become take over pacemaker role?

blockage occurs below the AV nodes; can be Bundle of His or Bundle Branches

Where does Type II/Mobitz occur?

blockage in the AV Node

Where does type I/Wenckebach occur?

Floor of the right atrium

Where is the AV node located?

Superior right atrial wall just inferior to opening of Superior Vena Cava

Where is the SA node located?

Superior portion of the interventricular septum

Where is the bundle of HIS located?

the beat is coming from above the ventricles or the SA or AV node in the atria.

Why would the QRS be narrow or normal?

uncoordinated and chaotic

what do the p waves of a-fib look like?

atrial fibrillation

what is the prototypical irregularly irregular rhythm?

because of common co-morbidities cause this - DM, HTN,...

why is a-fib so common?

the beat is coming from the ventricles

why would the QRS be wide?