41: assisting with cardiac monitoring

41: Assisting With Cardiac Monitoring

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 (1 of 2)

Objectives (2 of 2)

4. Identify the components of basic cardiac arrhythmias.

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.

*All of the objectives in this chapter are noncurriculum objectives.

• Use of 12-lead ECGs in the prehospital setting is becoming the norm.

• Early identification of AMIs allows hospitals to be prepared.

• The EMT-B should know how to place electrodes and leads.

Cardiac Monitoring

Electrical Conduction System (1 of 2)

• A network of specialized tissue in the heart • Conducts electrical current throughout the heart• The flow of electrical current causes contractions

that produce pumping of blood.

Electrical Conduction System (2 of 2)

The Process of Electrical Conduction

• Electrical conduction occurs through a pathway of special cells.

• SA node: the heart’s main pacemaker– Paces at a rate of 60–100 beats/min– Average of 70 beats/min

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• 60–100 beats/min

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)

Sinus Bradycardia

• Consistent P waves• Consistent P-R interval• Less than 60 beats/min

Sinus Tachycardia

• Consistent P waves• Consistent P-R interval• More than 100 beats/min

Ventricular Tachycardia

• Three or more ventricular complexes in a row

• More than 100 beats/min

Ventricular Fibrillation

• Rapid, completely disorganized rhythm• Deadly arrhythmia that requires immediate

treatment

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.

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

Lead Placement

• EMT-Bs can help in efficient cardiac monitoring by placing electrodes.

• Electrodes can be placed while ALS provider prepares other parts of call.

4-Lead Placement

• Four leads are called limb leads.

• Leads must be placed at least 10 cm from heart.

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

Troubleshooting

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

Review

1. Which of the following represents the normal path of electrical conduction through the heart?

A. SA node, AV node, internodal pathways, Purkinje system, bundle branches, bundle of His

B. Internodal pathways, SA node, AV node, bundle branches, bundle of His, Purkinje system

C. AV node, internodal pathways, bundle of His, SA node, Purkinje system, bundle branches

D. SA node, internodal pathways, AV node, bundle of His, bundle branches, Purkinje system

Review

Answer: D

Rationale: The cardiac electrical conduction system creates an electrical impulse and transmits it through the heart, through a specific pathway, in an organized manner. The normal path of electrical conduction is the SA node, the internodal pathways, the AV node, the bundle of His, the left and right bundle branches, and the Purkinje system.

Review1. Which of the following represents the normal path of electrical

conduction through the heart?

A. SA node, AV node, internodal pathways, Purkinje system, bundle branches, bundle of His

Rationale: The intranodal pathways come before the AV node.B. Internodal pathways, SA node, AV node, bundle branches,

bundle of His, Purkinje systemRationale: The SA node is before the intranodal pathways.C. AV node, internodal pathways, bundle of His, SA node, Purkinje

system, bundle branchesRationale: The SA node is always first.D. SA node, internodal pathways, AV node, bundle of His, bundle

branches, Purkinje systemRationale: Correct answer

Review

2. In the adult, the sinoatrial (SA) node normally paces the heart at a rate of:

A. 40 to 60 per minute.

B. 60 to 100 per minute.

C. 80 to 110 per minute.

D. 100 to 120 per minute.

Review

Answer: B

Rationale: For the heart to pump, one of the parts of the electrical conduction system must act as the pacemaker—the area that generates an electrical impulse. In a normally functioning heart, the sinoatrial (SA) node performs this function. In the adult, the SA node paces at a rate of 60 to 100 per minute, hence the normal adult heart rate of 60 to 100 beats/min.

Review

2. In the adult, the sinoatrial (SA) node normally paces the heart at a rate of:

A. 40 to 60 per minute.

Rationale: This would be bradycardia.

B. 60 to 100 per minute.

Rationale: Correct answer

C. 80 to 110 per minute.

Rationale: The normal rate is 60 to 100 beats/min.

D. 100 to 120 per minute.

Rationale: This would be tachycardia.

Review

3. The positive (red) lead should be placed on the patient’s:

A. left leg.

B. left arm.

C. right leg.

D. right arm.

Review

Answer: A

Rationale: Correct lead placement is important in order to obtain an accurate ECG tracing. When using a 4-lead configuration, the negative (white) lead is placed on the right arm, the ground (black) lead is placed on the left arm, the positive (red) lead is placed on the left leg, and the green lead is placed on the right leg.

Review

3. The positive (red) lead should be placed on the patient’s:

A. left leg.

Rationale: Correct answer

B. left arm.

Rationale: The left arm needs the black lead. Remember smoke is over fire.

C. right leg.

Rationale: The green lead is in a 4-lead configuration.

D. right arm.

Rationale: The right arm needs the white lead. Remember, white on the right.

Review

4. After applying the ECG leads to a patient with chest pain, you look at the cardiac monitor and note that all of the complexes are inverted. What has MOST likely happened?

A. The patient is experiencing a dysrhythmia

B. The ground lead is not properly connected

C. The patient is moving around excessively

D. The positive and negative leads are switched

Review

Answer: D

Rationale: An electrical impulse that is moving away from a negative pole and toward a positive pole will produce a positive deflection on the ECG tracing. If all of the complexes and waveforms are inverted on the ECG, the positive and negative leads are most likely switched. The electrical impulse is still moving toward a positive pole; you are simply viewing the opposite.

Review

4. After applying the ECG leads to a patient with chest pain, you look at the cardiac monitor and note that all of the complexes are inverted. What has MOST likely happened?

A. The patient is experiencing a dysrhythmia

Rationale: Dysrhythmias appear as unusual looking wave forms — not inverted.

B. The ground lead is not properly connected

Rationale: The ground will not give a reading.

C. The patient is moving around excessively

Rationale: Movement appears as artifact.

D. The positive and negative leads are switched

Rationale: Correct answer

Review

5. The QRS complex represents:

A. atrial depolarization.

B. ventricular contraction.

C. atrial repolarization.

D. ventricular depolarization.

Review

Answer: D

Rationale: The QRS complex represents ventricular depolarization, or discharge of electricity. Remember that the electrical impulse stimulates contraction of the heart. Contraction of the ventricles is evidenced by the presence of a pulse. The P wave represents atrial depolarization.

Review

5. The QRS complex represents:

A. atrial depolarization.

Rationale: This is represented by the p wave.

B. ventricular contraction.

Rationale: This is represented by the presence of a pulse.

C. atrial repolarization.

Rationale: Atrial repolarization occurs during the ventricular depolarization and does not show up as a wave form.

D. ventricular depolarization.

Rationale: Correct answer

Review

6. You are looking at an ECG tracing in which every waveform is upright and looks the same and the rate is 70/min. What is the name of the rhythm in which the SA node is acting as the pacemaker?

A. Junctional escape

B. Sinus tachycardia

C. Normal sinus rhythm

D. Atrial tachycardia

Review

Answer: C

Rationale: Normal sinus rhythm is characterized by waveforms and complexes that are all upright and look the same, and a rate between 60 and 100 per minute. Sinus tachycardia has all the components of a normal sinus rhythm; however, the rate is greater than 100 per minute.

Review6. You are looking at an ECG tracing in which every waveform

is upright and looks the same and the rate is 70/min. What is the name of the rhythm in which the SA node is acting as the pacemaker?

A. Junctional escapeRationale: This occurs when the SA node fails and the AV node

takes over, but the rate is 40 to 60 beats/min. B. Sinus tachycardiaRationale: It would look the same, but the rate is greater than

100 beats/min.C. Normal sinus rhythmRationale: Correct answerD. Atrial tachycardiaRationale: Multifocal atrial tachycardia presents with a rate

greater than 100 beats/min.

Review

7. When looking at the ECG paper, how much time is represented by 5 big boxes?

A. 1 second

B. 0.20 seconds

C. 0.04 seconds

D. 0.40 seconds

Review

Answer: A

Rationale: The smallest box represents 0.04 seconds (four-hundredths of a second). It takes five of the smallest boxes to represent 0.20 seconds (two-tenths of a second), which is equal to one big box. Five big boxes represents 1 second (0.20 × 5 = 1).

Review

7. When looking at the ECG paper, how much time is represented by 5 big boxes?

A. 1 second

Rationale: Correct answer

B. 0.20 seconds

Rationale: This would be five little boxes.

C. 0.04 seconds

Rationale: This would be one small box.

D. 0.40 seconds

Rationale: This would be ten little boxes or two big boxes.

Review

8. Ventricular tachycardia is characterized by:

A. Narrow QRS complexes and a rate between 140 and 200 per minute.

B. QRS complexes greater than 0.11 seconds and a rate greater than 100 per minute.

C. Inverted P waves, wide QRS complexes, and rate between 100 and 120 per minute.

D. QRS complexes greater than 0.06 seconds and a rate greater than 200 per minute.

Review

Answer: B

Rationale: The normal width of the QRS complex is 0.06 to 0.11 seconds. If the QRS width is greater than 0.11 seconds, it is considered wide. Ventricular tachycardia (V-tach) is characterized by wide (> 0.11 seconds) QRS complexes and a rate greater than 100 per minute. A rate between 140 and 200 per minute is common.

Review (1 of 2)

8. Ventricular tachycardia is characterized by:

A. Narrow QRS complexes and a rate between 140 and 200 per minute.

Rationale: The rate is greater than 100 beats/min but the QRS is greater than 0.11 seconds.

B. QRS complexes greater than 0.11 seconds and a rate greater than 100 per minute.

Rationale: Correct answer

Review (2 of 2)

8. Ventricular tachycardia is characterized by:

C. Inverted P waves, wide QRS complexes, and rate between 100 and 120 per minute.

Rationale: There are no P waves with ventricular tachycardia.

D. QRS complexes greater than 0.06 seconds and a rate greater than 200 per minute.

Rationale: The complexes must be greater than 0.11 seconds.

Review

9. Which of the following terms MOST accurately describes ventricular fibrillation?

A. Chaotic

B. Irregular

C. Slow

D. Wide

Review

Answer: A

Rationale: Ventricular fibrillation (V-fib) is a rapid, completely disorganized ventricular dysrhythmia with chaotic characteristics. V-fib is characterized by undulations of varying shapes and sizes with no specific pattern and no identifiable P waves, QRS complexes, or T waves.

Review

9. Which of the following terms MOST accurately describes ventricular fibrillation?

A. Chaotic

Rationale: Correct answer

B. Irregular

Rationale: There are no organized activity or identifiable waves.

C. Slow

Rationale: Ventricular fibrillation is not slow.

D. Wide

Rationale: Wave forms are chaotic and can be narrow, wide, or both.

Review

10. The 12-lead electrocardiogram (ECG) is used to:

A. identify and stop a myocardial infarction.

B. reperfuse areas of ischemic myocardium.

C. artificially increase the heart’s pacemaker rate.

D. identify areas of myocardial ischemia or injury.

Review

Answer: D

Rationale: The purpose of the 12-lead ECG—whether used in the hospital or prehospital setting—is to identify areas of myocardial ischemia, injury, or infarction. By doing this, the most appropriate treatment can be given. The ECG cannot stop a heart attack, nor can it reperfuse areas of ischemic myocardium; fibrinolytic medications (clot-busters) and invasive procedures (eg, cardiac catheterization) are used for this.

Review

10. The 12-lead electrocardiogram (ECG) is used to:

A. identify and stop a myocardial infarction.

Rationale: An ECG can identify if an acute MI is taking place, but it can not stop an MI from occuring.

B. reperfuse areas of ischemic myocardium.

Rationale: This can only be accomplished with medications.

C. artificially increase the heart’s pacemaker rate.

Rationale: A 12-lead does not produce energy that can act as a pacemaker.

D. identify areas of myocardial ischemia or injury.

Rationale: Correct answer