EKG Interpretation, part 10: Other EKG Abnormalities

by Cathy Parkes July 02, 2020

Full Transcript

In this video, we will be talking about some other EKG abnormalities that you may see, including a bundle branch block, a sinus pause, escape beats. And we will also talk about the impact of electrolyte imbalances on the EKG as well as some key respiratory and cardiac disorders, how those disorders affect an EKG as well.

 So one EKG abnormality I'd be familiar with is something called a bundle branch block or BBB. With a bundle branch block, the electrical impulse is delayed in the bundle of His or within the bundle branches. So this results in a very wide QRS complex. So the QRS complex will be over 3 small boxes in duration or over 0.12 seconds in duration. So if a patient has a bundle branch block but is asymptomatic, then it often doesn't require treatment. However, if the patient has a bundle branch block that is symptomatic, then we can treat that with either a pacemaker or cardiac resynchronization therapy or CRT. So here you can see in the EKG strip that we definitely have a consistent bundle branch block because that QRS complex is abnormally wide.

 Here we have a sinus pause, which is another EKG abnormality to be familiar with. We actually saw one of these when we were talking about premature atrial complexes, or PACs. So a sinus pause is caused when the SA node fails to initiate an impulse or that impulse somehow becomes blocked such that the atria do not depolarize. So during the sinus pause, we will not have the P wave, QRS complex, or the T wave. And then after the sinus pause, sometimes we will have what's called an escape beat, which I'll be talking about next. In terms of treatment, treatment is typically not required when a patient is asymptomatic.

 So an escape beat is an abnormal impulse that occurs after a sinus pause and occurs late. So I've included two examples of escape beats here. One is a ventricular escape beat. We know it's a ventricular escape beat because, as we talked about before, a key characteristic of a ventricular rhythm is an abnormally wide QRS complex. So with the ventricular escape beat, it is initiated in the ventricle. After the pause, the P wave will be absent, and the QRS complex will be abnormally wide.

With a junctional escape beat, this is initiated in the junctional foci which is at the AV junction, and it causes the P wave following a pause to either be absent, which it is here, or inverted, or it causes an abnormally short PR interval. So in this case, we just have an absent P wave, and then the QRS complex will be of normal duration when we're talking about a junctional escape beat. So for asymptomatic patients with escape beats, treatment is not typically required.

All right, now let's talk about how electrolyte imbalances can affect an EKG. The key electrolytes that you need to keep your eye on are potassium, calcium, and magnesium. So all the information I'm going to go over here in this portion of the video can be found on card 39 in my deck, if you are following along. So if a patient has hyperkalemia, meaning their potassium levels are too high, this can result in a peaked T wave, as well as a wide, flat P wave, or a wide QRS complex. If the patient has hypokalemia, meaning their potassium levels are too low, this can cause a flattened or inverted T wave, it can cause ST depression. It can also cause the presence of a U wave, which is this little wave that occurs after the T wave, and then lastly, it can caused increased amplitude and duration of the P waves.

For calcium, if the patient has hypercalcemia, which is too a high levels of calcium. This can cause a shortened ST and/or QT interval. If their calcium levels are too low, meaning they have hypocalcemia, this can cause a prolonged ST and QT interval.

And then moving on to magnesium. If the patient has hypermagnesemia, meaning their magnesium levels are too high, this can cause bradycardia as well as heart blocks. And then if they have hypomagnesemia, which means their magnesium is too low, this can result in tachycardia, a prolonged QT interval, as well as flattened or inverted T waves.

And then let's talk about how different cardiac disorders can impact an EKG as well. So if a patient has angina, this can result in ST depression as well as T wave inversion. If the patient is experiencing ischemia or a myocardial infarction, this can result in ST elevation, as well as T wave inversion and an abnormal Q wave. If a patient has pericarditis, this can also result in ST elevation on the EKG. Certain respiratory disorders can also cause EKG abnormalities. So if a patient has a pulmonary embolism or PE, this can result in ST elevation as well as an inverted T wave or a right bundle branch block. And then if a patient has COPD, this can result in a peaked P wave as well as a low-voltage QRS. So the QRS amplitude will be lower.

 So in my next video, which will be the last video in the series, we will talk about artificial pacemakers, and then we will talk about bradycardia and tachycardia in terms of the symptoms, the causes, and the treatment of those conditions. Thanks so much for watching!


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