The 7 Steps To Interpreting An EKG

An EKG alone is nothing more than a meaningless graph. To interpret it, it is necessary to evaluate various aspects and compare them with the available clinical data.

The electrocardiogram is one of the most widely used tests, especially in emergency departments and internal medicine. Interpreting it correctly is therefore decisive in many circumstances. Although this is a common test, its interpretation is not as straightforward as it might seem at first glance.

The electrocardiogram records electrical signals from myocardial cells. Indeed, each heartbeat emits an electrical signal which is recorded by the electrocardiograph. Its examination therefore makes it possible to visualize the activity of the heart and to detect possible alterations.

In itself, the EKG is nothing more than a linear figure. It simply leaves a trace that the professional interprets. To evaluate it, we follow a series of steps that we describe below.

Interpretation of an electrocardiogram

1. Check the conformity of the electrocardiogram

The first thing to do is to verify that the EKG has been performed correctly. The electrocardiograph should have a speed of 25 mm / s and an amplitude of 1 mV per 10 mm. If there is a suspicion of an error, then the test must be repeated.

If all goes well, the data and values ​​to be interpreted in this cardiac analysis are as follows:

2. Calculate the patient’s heart rate

The heart rate is of course the first relevant data extracted from an electrocardiogram. There are electrocardiographs that calculate it automatically.

But if it doesn’t, there are manual ways to do it. These include the 300 method, the 1500 method and the 6 second method.

Heart rate is the number of times the heart contracts to pump blood to the rest of the body. This allows us to establish whether there is tachycardia or bradycardia, aspects that are fundamental in identifying possible abnormalities or problems.

3. Assess the heart rate

The heart rate corresponds to the sequence of systoles and diastoles in the musculature of the heart. If this organ is normal, it contracts between 70 and 75 times per minute. In an EKG, it is represented in QRS complexes.

It is one of the easiest data to observe. It helps determine whether the heartbeat is regular or irregular. And also if it is normal sinus type or if it is sinus tachycardia or bradycardia.

4. Establish the electrical axis of the heart

This is one of the most difficult steps in interpreting an electrocardiogram. The electrical axis of the heart corresponds to the direction followed by the electrical stimulus as it passes through the ventricles. These data provide information on possible intraventricular conduction defects.

5. Evaluate the ST segment of the electrocardiogram

The QRS complex is the sum of the electrical discharges of all cells in the ventricles. On the other hand, there is the T wave, which represents the repolarization, or electrical recovery, of the ventricles. The distance between the QRS complex and the T wave is called the ST segment.

Sometimes the ST segment has an elevation or a descent. But if these values ​​are not significant, the situation can be considered normal. On the other hand, if the values ​​exceed the limit range, then ischemic heart disease is very likely.

6. Evaluate waves and intervals

It is important to perform an analysis of each of the waves, as well as each of the intervals that have not been evaluated. The PR interval and the QT interval are particularly important. When the PR interval is short, it means that there is accelerated atrioventricular conduction. When it is long, it means that the conduction is slowed down.

The QT interval represents the duration of ventricular electrical systole. It includes the QRS interval, ST segment and T wave. It is closely related to heart rate. When it is fast, the interval decreases and vice versa.

7. Schematic summary of the evaluation of an electrocardiogram

In summary, the steps to follow to interpret an EKG schematically are as follows:

• Determine heart rate
• Assess heart rate
• Define the axes
• Identify sinus rhythm (presence of Q waves before each QRS complex)
• Cycle through the PR interval
• Valuing the QT interval
• Evaluate QSR complexes
• Analyze the ST segment
• Evaluate T waves

Once all these steps have been carried out, it then remains to determine the anomaly or anomalies detected. From there, you can determine what actions to take or decisions to make.