QRS complex

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The QRS complex in lead V 1 with incomplete right bundle branch block

In medicine , the QRS complex , QRS group , chamber complex or simply QRS is a group of rashes in the electrocardiogram (EKG) caused by the depolarization of the two heart chambers.

description

The QRS complex can consist of a negative Q wave , one or two positive R waves, and one or two negative S waves , with small spikes with small letters (q, r and s) and large spikes with capital letters (Q , R and S). The size ( amplitude ) of the spikes varies from lead to lead and depends on the position of the electrical axis of the heart . The duration or breadth of the QRS complex varies slightly depending on age and gender. The upper limit mentioned most frequently is 0.12 seconds (120 ms), the normal QRS duration is usually given as 110–120 ms at most.

Q wave

The Q wave marks the beginning of ventricular excitation. It's a small negative rash. During the Q wave, the action potential is passed on from the apex to the base of the heart. The negative deflection results from the fact that this expansion runs against the direction of the heart vector / the heart axis. The conduction of excitation occurs particularly quickly in the papillary muscles, which pull from the apex of the heart to the atrioventricular valves. Since the action potential now arrives at the valves a little earlier than at the myocardial cells, these close a little early. This ensures that when the chambers contract, no blood can flow back from the ventricles into the atria. The Q wave should be no wider than 0.04 seconds (40 ms) and have an amplitude less than a quarter of the R wave. Broader and deeper ("pathological") Q waves can indicate an old heart attack or, in newborns, septal hypertrophy. Only negative chamber complexes are called QA complexes. If the beginning of the ventricular excitation has a positive swing, then it is already called the R wave and there is no Q wave in this lead.

R wave

The R wave represents the highest wave on the electrocardiogram, as this is where the greatest electrical activity can be found. This represents the depolarization of the myocardium (heart muscles) of both chambers. It is usually slim and large and varies depending on the electrical axis of the heart. Broadened and notched R-waves indicate a disturbance of the conduction of excitation in the heart and are observed in right bundle branch block and left bundle branch block. A reduced R-amplitude can indicate a previous heart attack. If another positive deflection occurs after the S-wave, this is designated as r 'or R' depending on the size.

S-point

A usually small negative rash on the EKG following the R wave is called an S wave. If a negative deflection follows an R 'or r' spike, it is given the designation S 'or s', depending on its size.

Upper transition point

The beginning of the final downward movement within the QRS complex is called the upper transition point (OUP) or the beginning of the greatest negative movement (GNB) or intrinsic deflection . It should occur in lead V 1 a maximum of 30 ms and in lead V 6 a maximum of 55 ms after the start of the QRS complex.

J point

The point at which the QRS complex merges into the ST segment is called the J point. It is important as a reference point for measuring the QRS width or an ST elevation or depression. A clear boundary between the QRS complex and the ST segment is not always recognizable, especially in the case of the more common QRS complex or inclined course of the ST segment. There is no clear consensus on how to define the J point then. Possible definitions are:

  • The first "turning point" at which the slope of the S-wave changes.
  • The point at which the EKG trace becomes more horizontal than vertical.

swell

Main source

  • G. Csapo: Conventional and Intracardiac Electrocardiography . Ed .: Ciba-Geigy GmbH, 1980, DNB 800958500 .
  • R. Schmidt, F. Lang, M. Heckmann: Physiology of humans. Springer, 2010, ISBN 978-3-642-01650-9 .

Individual evidence

  1. DM Mirvis, AL Goldberger In: DP Zipes et al. (Ed.): Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 7th edition. WB Saunders Company, Philadelphia 2004, ISBN 1-4160-0014-3 , pp. 114-128.
  2. Klinge, Rainer, 1943-: The electrocardiogram: guidelines for training and practice; 4 real-size exercise ECGs; 47 tables; 130 memory boxes . 10th, updated and expanded edition. Thieme, Stuttgart 2015, ISBN 978-3-13-166910-0 , p. 113 .
  3. ^ A b M. Herbert, J. Brownfield: EKG Criteria for Fibrinolysis: What's Up with the J Point? In: The western journal of emergency medicine . tape 9 , no. 1 , January 2008, p. 40-42 , PMID 19561701 , PMC 2672223 (free full text).
  4. monroecc.edu

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