Normal Sinus Rhythm

 Ventricular Fibrillation aka V-fib ( TERRIBLE hurry up and start some CPR & shock em’ and push some drugs)

Atrial Flutter (don’t want this either)

What is an EKG?

An EKG machine is a voltmeter. In other words, it reads electrical energy from the body. The heart uses electrical energy to cause muscle cells to contract. By reading the electrical energy of the heart, the nurse can tell if it is generated and conducted correctly.

An EKG is obtained by placing electrical sensors (leads) on the patient’s chest. Usually 12 leads are used to look at the heart from many angles. The EKG machine doesn’t look at all 12 leads at once; instead it chooses one at a time to view, and each view we call a lead on the resulting tracing.

What does it measure?

Electrical impulses are transferred to paper by the EKG machine. Two components of the tracing are especially useful: time and amplitude. Time is measured horizontally across the EKG strip. Amplitude is measured by the height of the tracing, which corresponds to the strength of the electrical impulse.

 EKG paper is divided into small squares and larger squares. Small squares are 1mm high and 0.04 seconds long. Large squares are five small squares high (5mm) and five small squares long (0.20 seconds).

Using the 5-step method

The EKG site uses a 5-step method to recognizing normal and abnormal EKG rhythms (see level 1). The five steps are listed below:

Step 1. Is the speed of the rhythm between 60-100?

Step 2. Is it regular?

Step 3. Is the complex narrow?

Step 4. Is it preceded by a P-wave?

Step 5. Do all the complexes look the same?

Step 1 evaluates the speed of the rhythm to determine if it is normal, too slow or too fast. A speed between 60-100 maintains the best hemodynamic stability. Rates less than 60 or greater than 100, can lead to hemodynamic instability and become symptomatic.

Step 2 asks if the rhythm is regular. Rhythms originating from the normal pacemakers in the heart will be regular. Irregular rhythms indicate extra beats or abnormal rhythms.

Step 3 assesses the shape of the complex. A narrow complex is normal. A wide complex indicates conduction abnormalities.

Step 4 asks if a P-wave precedes the QRS complex. This represents normal conduction from the atria to the ventricles. If the P-wave is absent, the impulse is being generated from elsewhere in the heart.

Step 5 assesses whether all the complexes look the same. Normal conduction follows the same pathway with each beat. Different looking complexes indicate the some impulses are following alternative or aberrant pathways.

The basics of 12-lead EKGs:

- Why look to the EKG?

- Why use 12-leads?

- Changes on the 12-lead

- 5-steps to 12-lead interpretation

  

 

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Why look to the EKG?

The electrocardiogram (EKG) is a device that receives electric impulses from the body and changes them into a monitor tracing that can be analyzed to find problems with electrical conduction in the heart. The EKG simply picks up electrical impulses; it does not read mechanical activity. When a patient has ischemia, injury or necrosis to the heart muscle, the electrical impulses change in the area involved. Nurses can analyze the electrical changes and determine if they indicate mechanical dysfunction.

Why use 12-Leads?

Traditional EKG monitoring is done with a single lead to assess for arrhythmias. However, a single lead provides only a single view of the heart. Consider the following analogy: if you were buying a house and wanted to show your friends what it looked like, a picture would give them some idea of the size and shape of the house. One picture wouldn’t show the sides or the back of the house, nor would it represent the layout of the house on the land it is on. Several pictures would do a much better job.

If you were to walk around the house and take pictures, you could show the back and sides of the house. How about an aerial photo? That would really show the lay of the land! These are the concepts behind the 12-lead EKG: the limb leads walk around the house, while the chest leads give the aerial view. By using twelve different views, many different parts of the heart can be assessed.

Changes on the 12-lead

The EKG is simply a volt meter that picks up electrical signals. Therefore, anything that interferes with electrical conduction can cause changes in the EKG. These variables can be divided into three main categories: 1) physiological variables not specific to the heart (ie. pulmonary embolism, increased intracranial pressure), 2) electrical interference (ie. poorly placed lead), or 3) ischemia, injury, or infarction.

The 5 Steps to 12-Lead Interpretation will help you differentiate between non-specific causes of EKG changes and actual cardiac problems by applying five simple rules:

5 Steps to 12 Lead Interpretation

1. Assess regularity and speed

2. Look for signs of infarction

3. Present in >1 lead, but not all?

4. Assess associated conditions

5. Correlate with clinical condition