Alteration in Perfusion: Cardiac Rhythms

Alteration in Perfusion: Cardiac Rhythms

• AV node broken- fall back is the ventricles 

• SA node is broken fallback is the SA 

• AV and SA node broken= V tech (the ventricles takes over) 

  • Side note: sodium and potassium need to be equal 

• If the current starts at the Av node→ A- fib

PR =

Atrial Depolarization (Contraction)

QRS =

Depolarization of Ventricles

T Wave =

Repolarization (Resting) of Ventricles

QT =

Time it takes to complete Ventricular Depolarization & Repolarization

Dysrhythmia

• Abnormal, disordered rhythm of the heart

• Interruption of automaticity

Dysrhythmia why is it important

• Decreases CO and O2 or high 02 or Co2

• Can cause clot formation (blood can’t perfuse through,, heart can die)  

• Can be fatal

Pacemaker Rules

• The pacemaker site with the fastest rate will generally control the heart.

Pacemakers Escape Mechanism

• The normal pacemaker slows down or fails, and a lower pacing site assumes pace making responsibility.

Pacemaker Rules Inherent Rates

• Sinus Node: 60-100 beats/min

• AV Node: 40-60 beats/min

• Ventricles: 20-40 beats/min  Insufficient to sustain cardiac output

Lead Placement for Telemetry Monitoring

• Right arm (RA): Near the right shoulder 

• Left arm (LA): Near the left shoulder 

• Right leg (RL): Below the lowest rib on the right side of the abdomen 

• Left leg (LL): Below the lowest rib on the left side of the abdomen 

• Chest (C,V[voltage]): In the fourth intercostal space, to the right of the sternum

Get the Best Picture for Teles and EKG

• Clip excessive hair on the chest wall. 

• Rub skin with dry gauze.

• May need to use alcohol for oily skin

• Keep away from bony prominences

• The positive electrode is the place where the picture is taken

Bipolar Leads are known as 

• limb leads: this leads are consist of a positive electrode and a negative electrode

Bipolar/Limb leads

• Lead I measures the current traveling between the right(RA) and left arm(LA).  The right arm is negative(-) and left arm is positive(+)

• Lead II current between RA and LL (left leg).  RA is negative(-) and LL is positive(+).  This gives the most upright P waves. 

  • How long it takes for the heart to contract 

• Lead III-current between LA(-) and LL(+)

VR, VL, VF

• aVR picture from heart looking toward R arm

• aVL picture of heart looking toward L arm

• aVF picture of heart looking toward L foot

P waves are

• upright (positive deflection) and rounded and should look the same

PR interval

•  beginning of the P wave's upslope to the beginning of the QRS wave. 

QRS interval:

• Q-first negative deflection after P, R-first upright deflection after the P, S-first negative deflection after the R

T wave

•  normal is broad and rounded.  If there is a QRS then a T wave must be after it.

Time…The 6 second strip

• voltage - how hard the heart is contracting

• 6 sec strips→ gives you heart rate when beats are multiplied by 10 

• Each small box is 0.04 sec

Isoelectric Line

 even electricity, important because it helps identify the positive and negative deflections 

• Pwave (+) 

• Q wave (-) 

• S wave (-) 

• T wave (+) 

P-R interval measurement

• 0.12–0.20 seconds (3 to 5 small blocks). It is measured from the beginning of the P wave's upslope to the beginning of the QRS wave.

• A longer PR interval could indicate a heart block. 

QRS width measurement

• is less than 0.12 seconds 

  • Begins at Q and ends at the end of the S wave

Q-T interval measurement

is 0.34–0.43 seconds. A prolonged QTc is defined as QTc > 0.43 sec.

RR interval measurement

•   0.6–1.2 seconds.

Abnormal…U wave

• Small, same direction as T wave. Usually in slow rhythms. May be low K+

Abnormal…T wave

• Peaked T waves can be result of hyperkalemia

  • Too much k+ → high her he K+ then higher the waves 

Abnormal…ST wave

• ST depression (not enough O2- ischemia) 

• ST elevation (cell death- infraction)

Abnormal…Bundle Branch Block

• Right Bundle Branch Block→ the right ventricle effected 

• Left Bundle Branch Block→ the ventricle is effected 

Interference

• Not true rhythms because they don’t have a pattern→ means patient movement or loose electrodes  

ECG Leads

ECG

• Graphic representation of the electrical forces produced within the heart

• aVR: upside down is normal

• Look at the heart from 12 different views (12 leads ?) → no, but shows 12 views of the heart

Defibrillator and Temporary Pacing

Pacing…Single and Dual Chamber

Pacemaker Spike

Pacemaker Malfunction

• Pacemaker fires, but no capture occurs.

• ECG has a spike not followed by a complex.

  • Lead damage, battery failure, dislodgement of the electrode, fibrosis at the electrode tip

Failure to Capture Pacer maker malfunctions:

Electrical charge to myocardium is insufficient to produce atrial or ventricular contraction

Which information will the nurse include when teaching a patient who is scheduled to have a permanent pacemaker inserted for treatment of symptomatic bradycardia?

A. The pacemaker prevents or minimizes ventricular irritability.

B. The pacemaker paces the atria at rates up to 500 impulses/minute.

C. The pacemaker discharges if ventricular fibrillation and cardiac arrest occur.

D. The pacemaker stimulates a heart beat if the patient’s heart rate drops too low.