Adult Health Exam 3

12-lead ECG

Provides info about the contraction and relaxation of atria and ventricles

Only 10 electrodes!

Depolarization on ECG

Contraction

Repolarization on ECG

Relaxation

Placing electrodes

30-40 degrees to find intercostal

Clean skin

Remove excessive hair

Connect wires prior to sticking

Ambulatory electrocardiography

Outpatient

Holter, implantable loop recorder, mobile cardiac telemetry

P wave

Atrial depolarization

PR interval

From start of P to start of QRS

Represents conduction from SA node to AV node

0.12-0.20

Abnormal PR interval

May indicate heart block

QRS complex

Ventricular depolarization and atrial repolarization

<0.10

J point

Where the QRS ends and the ST segment begins

If it’s above the isoelectric line indicated ischemia

ST segment

Shows signs of ischemia
Represents early ventricular repolarization

T wave

Ventricular repolarization (relaxation)

Abnormal T wave

Ischemia or abnormal K+

Peaked T wave

High K+

Inverted T wave

Ischemia/hypokalemia → prevent ventricle from repolarizing properly

U wave

Repolarization of the Purkinje fibers

Hypokalemia, HTN, heart disease

QT interval

Total time for ventricle depolarization and repolarization

<0.48

Prolongued QT

Increases risk for torsade the pointes

PP interval

Used to determine atrial rate and rhythm

RR interval

Used to determine ventricular rate and rhythm

ST segment depression

Evidence of ischemia

ST segment elevation

Acute MI

Q waves

Necrosis and evidence of a previous infarction

Normal QRS duration

<0.10 sec

Artifact

Interference not related to heart

Poor electrode contact, client moves, malfunctions

Sinus arrythmias

SA node creates impulse at irregular rhythm

Often related to respiration and not clinically significant

Younger peeps

Sinus bradycardia

SA node <60bpm

Otherwise normal and regular rhythm

Causes for sinus bradycardia

Lower metabolic needs

Vagal stimulation

Medications (CCB, amiodarone, BB)

ICP

Rare: Inferior MI

Sinus bradycardia tx

Only if symptomatic!

Transcutaneous pacing

Atropine

Dopamine/epi → if ineffective pacing

Withhold meds that cause brady

IV fluids

Sinus tachycardia

SA generates rate >100bpm

Otherwise normal

Sinus tachycardia causes

Physical/psychological stress → pain, PE, shock, fever, anxiety

Medications → stimulate sympathetic response

Stimulants/illicit drugs

Pathway of electrical activity in the heart

SA node

AV node

Bundle of His

Bundle branches

Purkinje fibers

Golden rule of contraction

Mechanical contraction ALWAYS comes after electrical conduction

Premature atrial contractions (PACS)

Benign early firing of heartbeat from irritated atrial nodes

No tx needed

Causes of PACS

Unknown

MI, HF, HTN

Medications

Common in 20s-30s

Randomly happen and go away

Supraventricular tachycardia (SVT)

Complex tachycardia caused by overexitability of atria

“Super excited to tell the ventricles”

Causes of SVT

Stress/substance use

PMH: Heart/lung disease

Wolff-Parkinson-White Syndrome

Pregnancy

s/s of SVT

HR >110

Hypotension

SOB

Palpitations/discomfort

Dizziness

SVT tx (in order)

Valsalva maneuvers → blowing into straw

Adenosine

IV Metoprolol/diltiazem

Syncronized cardioversion

Ablation

Characteristic of SVT ECG

No discernible P wave

Adenosine MOA

Decrease electrical conduction through AV node and decrease automaticity in SA node → reset the rhythm

Adenosine classification

Other antidysrhythmic

Adenosine adverse effects

Asystole!

Sinus bradycardia

Hypotension

Dyspnea

Facial flushing

Adenoside contraindications

AV block

Atrial flutter

Afib

Caution: Asthma and older adults

Adenosine nursing implications

Admin as quick as possible

Begin w 6mg → 20mL flush → 12mg → flush

Use port closest to heart

12-lead continuous monitoring

Crash cart in the room