Share this:

QRS Complex – Nomenclature


QRS complex on ECG is the graphic representation of ventricular depolarization.


1) What is a wave in QRS complex?

Wave is actually the deflection away from in reference to isoelectric line.

Deflection above in reference to isoelectric line is a positive wave.

Deflection below in reference to isoelectric line is a negative wave.


2) What is an isoelectric line?

Isoelectric line is the “TP” segment on the E.C.G ; the line between the end of “T” wave and start of “P” wave.

“PR” segment and “ST” segment cannot be called as isoelectric lines because in some pathologies they can be raised or depressed.


3) Factors determining the QRS complex:

Nomenclature of QRS depends upon:

a) Direction of deflection of wave:

Whether it is a positive deflection or negative deflection.

b) Position of wave within the complex:

Negative deflections coming before and after the positive deflection are given different names. If a negative deflection is coming before a positive deflection “R” wave is given a name “q” wave , if a negative deflection is coming after a positive deflection “R” wave it is given a name “s” wave.

c) Degree Of deflection:

i) Small deflection (wave): Represented by small letter e.g. “q” , “r” , ”s”.

ii) Large deflection (wave): Represented by a large letter e.g. “Q”, “R” ,”S”.


4)Rules for QRS complex:

a) Initial negative wave is always “q” or “Q” wave.

b) First positive wave is always “r” or “R” wave.

c) Negative wave after “R” or “r” wave is a whether “S” or “s” wave.

In QRS complexes the first positive wave is “R” wave and any wave coming before the “R” wave is a “q” wave and wave after the “R” is a “s” wave.

d) If there is a second positive deflection within the QRS complex it is called as R’ (R prime) and if there is second negative deflection after the R’ it is called as s’ (s prime) .

e) Small deflections are designated by small letters “s” , ”r” and large deflections are represented by large letters “R” “S” “Q” “R’” “S’”.

f) If the amplitude of the deflection is more than three small squares it is considered as large deflection and if it is less than 3 squares than it is considered as small deflection.


5) Triphasic QRS Complex:

Triphasic QRS complex is a complex when there are 3 waves present in the QRS complex. e.g. qRs , rSr’, RSR’.


6) Biphasic QRS complex:

Biphasic QRS complex is a complex when there are 2 waves present in a QRS complex. e.g. qR , QR, Qr, qr, Rs, rs, rS.


7) Monophasic QRS complex:

Monophasic QRS complex is a complex when there is only 1 wave present in a QRS complex

Note:To label a negative wave as “q” or “s” we must have a “R” wave.

Sometimes there is a QRS complex which does not have a positive deflection and has only a negative deflection, so we will label it as “QS” or “qs” depending upon the amplitude of a wave.

QRS complex is a name given to any wave complex produced by the ventricular depolarization it can have 1,2,3 waves and will call as Monophasic, Diphasic and Triphasic respectively.


 

Students from Top Schools are watching our videos!

qrs complex  

Not a member? Sign up now to access 700+ videos on Basic Medical Sciences & Clinical Medicine. Free Access to new videos every week. Master Medical Sciences with crystal clear concepts.


 

About Dr. Najeeb Lectures.

Dr. Najeeb Lectures are the World’s Most Popular Medical Lectures. Our videos are being watched by millions of Medical, Dentistry, Nursing and Pharmacy students in over 100 countries.

We have 700+ videos on Anatomy, Neuroanatomy, Embryology, Histology, Physiology, Biochemistry, Genetics, Pharmacology, Microbiology, Immunology, Pathology and Clinical Medicine all recorded by Dr. Najeeb.

 
 

What makes us different?

We use hand-drawn illustrations to empower your learning process because we believe lasting knowledge results from clear concepts. Our videos are interactive and fun to watch so you don’t have to spend hours memorizing.

They say a picture is worth a thousand words, we have integrated that philosophy in our every lecture. We are Revolutionizing Medical Education through hand-drawn illustrations. One concept at a time.

 

VIDEO LIBRARY        SIGN UP

Here’s what students are saying about Dr. Najeeb Lectures.

Lizi Klein Los Angeles, California
Lizi Klein
This is singularly the best investment I made for the first year of medical school. Each video is a jackpot of information with amazing drawings, great energy, and a phenomenal professor!
Kathryn Giroux Whitefish, Ontario
Kathryn Giroux
Currently, the only things saving my embryology and 1st-trimester ultrasound marks – keep the wealth of education flowing! Highly recommended!
Maryam Moradi The University of Texas, Austin
Maryam Moradi
I bought lifetime access because I believe there is no better source for learning the foundation of medicine. I strongly recommend him to anyone who cares about true learning and not merely memorizing!
Jackson David Reynolds University of North Georgia
Jackson David Reynolds
Dr. Najeeb Lectures are top notch. Comprehensive medical lectures of the utmost quality across all preclinical (and many clinical) topics. Fantastic for deepening one’s understanding for clinical practice and licensing/board examinations.
Jacob Joseph Columbus, Ohio
Jacob Joseph
Dr. Najeeb is the single most spectacular medical teacher you will ever have! I love this man. He has clarified everything from the coagulation cascade, immunology, neurology, and embryology. His sense of humor and brilliant illustrations make everything stick well in your memory. His ability to illustrate 3-dimensional relationships has been useful for excelling in anatomy. I cannot thank you enough for all the wonderful work you do. I recommend your lectures to anyone who wants to truly understand medicine!
Ann Ilaria Mayrhofer London School of Hygiene.
Ann Ilaria Mayrhofer
I’m grappling with my online studies in Infectious Disease at London School of Hygiene and Tropical Medicine. It’s made me realize what a visual learner I still am. So these vids are making what was murky crystal clear. While I am easily distracted when I have to do hours of straight reading, I am glued to the videos. I’ve looked for a series of such videos for months. A million thanks – Dr Najeeb has a true passion for teaching and can convey highly complex topics in an understandable and fun way.


Not convinced? Read more!