Cardiac monitoring Egan’s Ch. 17, CARC Ch. 11. Objectives (1 of 2) 1.To gain an understanding of...

Cardiac monitoring

Egan’s Ch. 17, CARC Ch. 11

Objectives (1 of 2)

1. To gain an understanding of basic terminology and techniques of cardiac monitoring.

2. To give you the knowledge and tools you need to assist the advanced provider with the use and implementation of an ECG.

3. To better understand the basic anatomy and physiology of the heart.

Objectives (2 of 2)

4. Identify the components of basic cardiac arrhythmias (because many times the RTs are with the patient during the onset of the initial event).

5. Evaluate the rate and rhythm of a patient’s cardiovascular system, and become familiar with the normal ECG.

6. Familiarize yourself with and apply 4-lead electrodes and identify placements for the 12-lead systems.

Cardiac Monitoring

• Use of 12-lead ECGs in the hospital is essential for cardiac patients.

• Early identification of AMIs allows hospitals to be prepared.

• The RT should know how to place electrodes and leads.

Electrical Conduction System (1 of 2)

• A network of specialized cells in the heart • Conducts electrical current throughout the

heart• The flow of electrical current causes

contractions that produce pumping of blood.

VIDEO

The Process of Electrical Conduction

• Electrical conduction occurs through a pathway of special cells.

• Automaticity– Ability of heart cells to generate a spontaneous

electrical impulse

• Sinoatrial (SA) node: the heart’s main pacemaker– Paces at a ventricular rate of 60–100 beats/min**Any beat that originates outside the SA node is called

“ectopic”**

The Process of Electrical conduction

• Atrioventricular Junction- electrical bridge between atria and ventricles, comprised of:– (AV) node– Bundle of His

• AV node– Acts as secondary (backup) pacemaker– Paces at a ventricular rate of 40-60 beats/min– Impulse is temporarily delayed here to allow better

filling of the ventricles– Protects ventricles from excessively fast rates

The Process of Electrical conduction

• Bundle branches• Purkinje fibers

– Fingerlike projections that pass electrical impulses throughout myocardium to create a coordinated contraction of the ventricles

Electrical Conduction System (2 of 2)

• VIDEO

Formation of the ECG (1 of 4)

Formation of the ECG (2 of 4)

Formation of the ECG (3 of 4)

Formation of the ECG (4 of 4)

Electrodes and Waves

Electrodes pick up electrical activity of the heart.

The ECG Complex

One complex represents one beat in the heart. Complex consists of P, QRS, and T waves.

ECG Paper

Each small box on the paper represents 0.04 seconds.

Five small boxes in larger box represents 0.20 seconds.

Five large boxes equal 1 second.

Normal Sinus Rhythm Consistent P waves Consistent P-R interval (0.12-0.20 seconds) 60–100 beats/min QRS < 0.12 seconds

Sinus Bradycardia

• Consistent P waves• Consistent P-R interval• Less than 60 beats/min• Potential causes are: Hypoxia, hypothermia, heart

disease, electrolyte imbalances(hyperkalemia), parasympathetic stimulation, hypothyroidism

Sinus Tachycardia • Consistent P waves• Consistent P-R interval• 100 – 160 beats/min• Potential causes are: Fever, pain, hyperthermia,

anxiety, medications, hypoxia, sympathetic stimulation

First Degree Block

• Impulse delayed at AV node• Prolonged PR interval• There is always concern that the patient will

progress to the next worse rhythm

2nd Degree Type I (Wenckebach)

• PR progressively longer until a QRS is dropped.

2nd Degree Type II (Mobitz)

• Nonconducted P waves followed by conducted P waves.

3rd Degree Heart Block• Ventricles and atria beat independently of one

another.• There is no relationship between the P waves

and QRS complexes• The patient will need a pacemaker

– Usually a temporary pacer (TCP) until a permanent one can be inserted

Atrial Flutter• Rapidly firing ectopic site in atria• Characteristic “sawtooth” pattern• At risk for thrombi• Rate: 180-400 beats/min• May progress to atrial fibrillation

Atrial Fibrillation

• Multiple ectopic sites within atria• Atrial rate > 350 beats/min• Decrease in ventricular filling

PVC’s• Wide and bizarre QRS complex is the most distinguishing

feature• No P wave prior to PVC• Bigeminyand trigeminy • Unifocal and Multifocal

– Multifocal is more concerning because there are multiple irritated areas in the ventricles

• Occasional PVC is ok but > 6/min is a sign of irritability• May progress to ventricular tachycardia• Treatment

– Lidocaine (decreases ventricular irritability)– Find the problem and fix it!

PVC’s

Supraventricular Tachycardia (SVT)• Impulse moves from atria – ventricles – atria

(circular)• Rate: 160-220 beats/min• P waves may be unidentifiable, normal QRS• Treatment

– If stable and narrow complex can try adenosine or vagal maneuvers

– If unstable, then immediate cardioversion

Ventricular Tachycardia Three or more PVC’s in a row Rate: 100-250 beats/min No distinguishable P waves Precedes or follows V-fib Treatment

If stable, treat with amiodarone If unstable with a pulse, then cardioversion Pulseless VT is treated with CPR and defibrillation just like VF

Ventricular Fibrillation Rapid, completely disorganized rhythmDeadly arrhythmia that requires immediate treatmentA new onset is coarse and will progress to fine VF which

is harder to defibrillateFine VF can be confused with asystoleTreatment is CPR and immediate defibrillation

Pulseless Electrical Activity (PEA)

• Pattern does not generate a pulse.• May show normal QRS complexes• Can be any kind of a pattern from NSR to one

or two complexes• Treatment is CPR and identify the cause (H’s

and T’s)

Asystole

• Complete absence of electrical cardiac activity

• Patient is clinically dead. • Decision to terminate resuscitation efforts

depends on local protocol.

Cardiac Monitors

• May be 3-, 4-, or 12-lead system• Compact, light, portable• Many monitors now combine functions

beyond ECG.

4-Lead Placement

Four leads are called limb leads.

Leads must be placed at least 10 cm from heart.

12-Lead ECG

• Used to identify possible myocardial ischemia• Studies show 12-lead acquisition takes little

extra time. • Early identification of acute ischemia and

accurate identification of arrhythmias

12-Lead Placement Limbs leads placed at

least 10 cm from heart. Chest leads must be

placed exactly.

Lead Location View

V1 4th intercostal space, right sternal border Ventricular septum

V2 4th intercostal space, left sternal border Ventricular septum

V3 Between V2 and V4 Anterior wall of left ventricle

V4 5th intercostal space, midclavicular line Anterior wall of left ventricle

V5 Lateral to V4 at anterior axillary line Lateral wall of left ventricle

V6 Lateral to V5 at midaxillary line Lateral wall of left ventricle

Holter monitoring

• Portable, battery powered recording device• Done over 24 hours• Useful in patients experiencing irregular heart

beats on an inconsistent basis.

Troubleshooting

• Clean skin. • Use benzoin.• Shave hair.