What does depolarization refer to in the context of an EKG?

The contraction of the heart muscle muscles is caused by depolarization. Therefore, an EKG can be used to indicate whether the heart muscle has contracted. Without an external stimulus, the cells of the heart can depolarize. This characteristic of cardiac muscle tissue can be called automaticity or autorhythmicity.

What does the QRS complex, then?

The QRS complex is the electrical impulse that travels through the ventricles. It indicates ventricular depolarization. The QRS complex begins just before ventricular contraction, as with the P wave. Not all QRS complexes will contain Q, R and S waves.

Another question is: What happens to ventricular depolarization, you may ask? Atrial depolarization is followed immediately by contraction (atrialsystole), an elevation in pressure in the ventricles (a wave) and a slight increase in ventricular volume. Ventricular depolarization can be followed by contraction (ventricular Systole), and an increase of pressure in the ventricles.

What is depolarization and what is repolarization in ECG, then?

The heart experiences depolarization and then repolarization. This causes electrical currents to spread throughout the body. The sequence of depolarization/repolarization that takes place in the ventricles and atria is represented by the ECG waves.

What are the T waves and P QRS?

The ECG shows ventricular and atrial depolarization as a series if waves. The Pwave is associated with both right and left atrial polarization. The QRS complex is the second wave.

17 Related Question Answers Found

What does it mean when QRS complex is inverted?

The QRS complex is ventricular depolarization. The T wave is ventricular repolarization. It is typically much wider than the ventricular depolarization that generates the QRS. Sometimes it is upside down (inverted). Sometimes half of it is upside down and the other half upright; this is called biphasic.

What does QRS stand for?

QRS

Acronym	Definition
QRS	Quote Request System (software)
QRS	Quality Reliability Service (various locations)
QRS	Quasi-Random Signal
QRS	Quantronic Resonance System

Why is my ECG upside down?

An ECG rhythm will appear upside-down if the mobile device is not properly oriented while the data is being acquired. You may invert an ECG that has previously been recorded by tapping the screen while reviewing the ECG in the Kardia app, and tapping the 'Invert' button that appears in the bottom right corner.

What are Q waves?

By definition, a Q wave on the electrocardiogram (ECG) is an initially negative deflection of the QRS complex. Technically, a Q wave indicates that the net direction of early ventricular depolarization (QRS) electrical forces projects toward the negative pole of the lead axis in question.

What is high QRS voltage?

High Voltage QRS Morphology

Increased QRS voltage is often taken to infer the presence of left ventricular hypertrophy. However, high left ventricular voltage (HLVV) may be a normal finding in patients less than 40-45 years of age, particularly slim or athletic individuals.

What is the normal QRS?

The normal duration (interval) of the QRS complex is between 0.08 and 0.10 seconds — that is, 80 and 100 milliseconds. When the duration is between 0.10 and 0.12 seconds, it is intermediate or slightly prolonged. A QRS duration of greater than 0.12 seconds is considered abnormal.

What does the ST segment represent?

The ST segment is the flat, isoelectric section of the ECG between the end of the S wave (the J point) and the beginning of the T wave. The ST Segment represents the interval between ventricular depolarization and repolarization.

What is repolarization of the heart mean?

In neuroscience, repolarization refers to the change in membrane potential that returns it to a negative value just after the depolarization phase of an action potential which has changed the membrane potential to a positive value.

What does depolarization of the heart mean?

Depolarization of the heart leads to the contraction of the heart muscles and therefore an EKG is an indirect indicator of heart muscle contraction. The cells of the heart will depolarize without an outside stimulus. This property of cardiac muscle tissue is called automaticity, or autorhythmicity.

What is the difference between repolarization and depolarization?

The membrane of a cell (e.g. a neuron) is polarized (negative inside). Depolarizing is when the membrane potential moves toward zero. Repolarizing is when it moves back negative after depolarization. Despite this, the entire rising phase of the action potential is usually (and lazily) referred to as “depolarizing”.

What causes depolarization?

As the membrane potential is increased, sodium ion channels open, allowing the entry of sodium ions into the cell. The inward flow of sodium ions increases the concentration of positively charged cations in the cell and causes depolarization, where the potential of the cell is higher than the cell's resting potential.

What does depolarization mean?

In biology, depolarization is a change within a cell, during which the cell undergoes a shift in electric charge distribution, resulting in less negative charge inside the cell. Depolarization is essential to the function of many cells, communication between cells, and the overall physiology of an organism.

What is repolarization of the heart?

The last event of the cycle is the repolarization of the ventricles. It is the restoring of the resting state. In the ECG, repolarization includes the J point, ST segment, and T and U waves. The transthoracically measured PQRS portion of an electrocardiogram is chiefly influenced by the sympathetic nervous system.

How does depolarization and repolarization occur in the heart?

Each deflection (wave) of the ECG represents either depolarization or repolarization of the specific parts of the heart. Because depolarization occurs before mechanical contraction, the waves of depolarization can be associated with contraction and relaxation of the atria and the ventricles.

Is depolarization when the heart contracts?

Atrial depolarization initiates contraction of the atrial musculature. As the atria contract, the pressure within the atrial chambers increases, which forces more blood flow across the open atrioventricular (AV) valves, leading to a rapid flow of blood into the ventricles.

What causes repolarization of the heart?

Repolarization (phase 3 of the action potential) occurs because of an increase in potassium permeability. At the SA node, potassium permeability can be further enhanced by vagal stimulation. This has the effect of hyperpolarizing the cell and reducing the rate of firing. Sympathetic stimulation has the opposite effect.

What are the 5 phases of the cardiac cycle?

5 Phases of the Cardiac Cycle

Atrial Systole.
Early Ventricular Systole.
Ventricular Systole.
Early Ventricular Diastole.
Late Ventricular Diastole.

What does depolarization refer to in the context of an EKG?

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