EKG: Introduction

Introduction: Overview

Focus topic: Introduction

Electrocardiogram, or EKG—also referred to as ECG—is a diagnostic test, performed at the bedside, that assists in the assessment of problems or disturbances with the electrical activity of the heart. This electrical activity within the heart is observed by means of an external EKG machine that connects via cables to electrodes. These electrodes are placed on the patient’s skin where they detect the heart’s electrical impulses. These electrical impulses are then “translated” by the EKG machine and recorded as line tracings on paper.

The tracings on the special paper are referred to as a “12 lead.” A “rhythm strip” is different than an EKG. An EKG looks at all angles of the electrical conduction system providing 12 views. (There are also 15- and 18-lead EKGs that are performed to diagnose specific myocardial infarction processes.) A “rhythm strip” shows one lead. This is useful to determine rate and rhythm and as an ongoing tool during patient observation. Today’s cardiac monitors have many tools built into them to assist health care personnel to screen for patient problems. A rhythm strip can also be produced by an EKG machine.

Normal EKG strip shows a normal EKG strip and 12-lead electrocardiogram shows a 12-lead EKG. By the time you finish this book, you will be able to recognize a normal EKG rhythm strip that can be obtained from an EKG tracing or a cardiac monitor, identify all the common electrical cardiac abnormalities, and understand common concepts relative to the EKG and disease processes.

Introduction: Normal EKG strip

Focus topic:  Introduction



 Introduction: 12-lead electrocardiogram

Focus topic:  Introduction



 Introduction: History of EKG

Focus topic:  Introduction

Willem Einthoven, a Dutch physiologist, introduced the EKG in 1903. Although Carl Ludwig and his student Augustus Waller are credited with initially tracing the heartbeat onto a phonographic plate fixed to a toy train that allowed the heartbeat to be recorded in real time in 1887, Einthoven perfected this system in 1903 to create a much more sensitive device. Einthoven’s participants would immerse each of their limbs into containers of salt solution from which the EKG was recorded as opposed to today’s method of using self-adhesive electrodes. This original machine weighed 500 pounds and required multiple people to function.

Einthoven assigned the letters P, Q, R, S, and T, still used today, to the waves and segments. This earned him the Nobel Prize in Medicine in 1924.




Many advances have been made in electrocardiography through the decades. Once cumbersome laboratory machines, today’s EKG devices are compact electronic systems that offer computerized interpretation of EKG. In keeping with the future’s mobile trends, a sleek, low-power wireless case can be attached to a smartphone to transform the phone to a clinical-quality cardiac event recorder with the help of a smartphone application.

Clinical Uses of EKG
The clinical uses of EKG are vast. EKGs are utilized in every aspect of health care. They can be used in physician’s or provider’s offices or in any department in the hospital environment including (but not limited to) the emergency department, medical/surgical departments, intensive care units, labor and delivery, surgery, postanesthesia care unit, and pediatrics. EKGs are also used routinely in the prehospital setting, often being electronically transmitted to the emergency department physician prior to arrival. They can also be completed in a patient’s home by home health care agency personnel or individuals who work for insurance companies. EKGs may be performed at health screenings, routine physical examinations, or presurgical workups in a planned elective situation. They are also an emergent diagnostic tool in potentially life-threatening situations. The individual receiving an EKG ranges from someone who is initiating a new exercise regimen to a person who is having chest pain. The use of the EKG is cross-generational, providing clues to care for all age groups from the infant with congenital heart disease to the centenarian with shortness of breath.

EKGs are also performed to determine heart rhythms that are different than the normal rhythm when abnormal electrical impulses disturb the cardiac cycle. These are called arrhythmias or dysrhythmias (EKG strip showing dysrhythmia). These terms are usually used interchangeably; however, “dysrhythmia” is more accurate since the term “arrhythmia” can officially mean an absence of heart rhythm. In this book, the term dysrhythmia will be utilized to differentiate an abnormal rhythm. These dysrhythmias will be explored in detail later in this book.

 Introduction: EKG strip showing dysrhythmia

Focus topic:  Introduction



Clinical Alert

During dysrhythmia, the heart can beat too fast (tachycardia), too slow (bradycardia), or with an irregular rhythm.

EKG is used to

  • Assess heart rhythm (rate and regularity of heartbeats)
  • Diagnose poor blood flow to the heart muscle (ischemia)
  • Diagnose a heart attack (myocardial infarction)
  • Diagnose abnormal electrical conduction of the heart
  • Diagnose heart chamber enlargement
  • Measure the effects of drugs or devices used to regulate the heart (such as a pacemaker or cardiac medications)

An EKG may be recommended for patients who experience the following signs and symptoms:

  • Chest pain (angina)
  • Breathing problems
  • Tiredness and weakness
  • Unusual heart sounds found upon auscultation
  • Unusual heartbeat, fluttering, racing, or pounding An EKG can show
  • Dysrhythmia
  • Birth defects in the heart (congenital heart defects)
  • Problems with the heart valves (endocarditis)
  • A heart that does not pump blood forcefully enough (heart failure)
  • Lack of blood flow to the heart muscle (coronary heart disease)
  • Inflammation of the sac that surrounds the heart (pericarditis)
  • Heart muscle that is too thick or parts of the heart that are too big (cardiomyopathy)


 Introduction: Who Can Perform an EKG?

Focus topic:  Introduction

An EKG may be performed by health care workers who have received specific EKG training, such as physicians, physician assistants, nurse practitioners, nurses, certified nursing assistants, medical assistants, paramedics, emergency medical technicians, cardiac technicians, and specifically EKG technicians. Training includes EKG operation and troubleshooting, electrode placement, use of EKG grid paper, and the recognition of normal and abnormal EKG patterns.

Health care workers can obtain this training from their educational institutions. However, most EKG technicians are trained on the job in a facility by an EKG supervisor or a cardiologist. On-the-job training usually lasts 8 to 16 weeks. Certification programs that can last up to 1 year are also available and offer programs for basic EKG, Holter monitoring, and stress testing. Holter monitoring involves equipping the patient with a portable EKG monitor that attaches to the patient’s belt and electrodes that reside on the patient’s chest. The patient’s normal activity is monitored for 24 or 48 hours in order to detect any abnormal heart rhythms. The test results are printed out and interpreted by a specialist to diagnose heart conditions such as dysrhythmias and pacemaker problems.

A stress test involves recording a patient’s base EKG reading while the patient stands still. Then the patient is asked to first walk and then run on a treadmill as the technician increases the treadmill’s speed. The specialist then interprets the test results to determine the effect this increased exertion has on a patient’s heart. Stress tests can also be performed with medications that speed up the heart for those patients who cannot walk on a treadmill.

Clinical Alert

State laws vary as to which medical professionals can legally interpret EKG results for diagnostic purposes. In all states, physicians can interpret EKG results. Do not provide a patient with an interpretation of EKG results unless it is within your scope of practice to do so.


 Introduction: Conclusion

Focus topic:  Introduction

Electrocardiogram is a diagnostic test that checks for problems with the electrical activity of the heart. EKG is used to identify and diagnose a wide range of heart problems. Note these key points:

  • An EKG machine is an external device that uses electrodes attached to the patient’s skin to detect the heart’s electrical impulses.
  • Special paper records the EKG tracings.
  • Willem Einthoven created the EKG in 1903 and won a Nobel Prize in Medicine for its creation in 1924.
  • EKG is used to assess heart rhythm; diagnose poor blood flow to the heart muscle; diagnose a heart attack; diagnose abnormal electrical conduction of the heart; diagnose heart chamber enlargement; and measure the effects of drugs or devices used to regulate the heart.
  • EKG may be recommended for patients who experience angina; breathing problems; tiredness and weakness; unusual heart sounds; and unusual heartbeat, fluttering, racing, or pounding.
  • EKG can provide evidence for dysrhythmias, congenital heart defects, heart valve disease, heart failure, coronary heart disease, pericarditis, and cardiomyopathy.
  • EKG may be performed by health care workers who have received specific EKG training, such as physicians, physician assistants, nurse practitioners, nurses, certified nursing assistants, medical assistants, paramedics, emergency medical technicians, cardiac technicians, and specifically EKG technicians.
  • EKG is performed in the clinical setting such as a physician’s office, health clinic or hospital, and in other areas such as the patient’s home.



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