QRS Is related to .....
A. Atrial contraction
B. Ventricular contraction
C. Atrial relaxation
D. Ventricular relaxation
srishti1927:
answer is B
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Answered by
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Hi FrIeND ur ans is
::::::::::::::::::::::::::::::::::
QRS is related to ventricular contraction
This is because the ventricles followed by ventricles contraction.The depolarization is equal to the contraction for which QRS is related.
As it complexes downwards deflection of the triangular waves and it is passed to the downward waves.
Be bRaINly
---------------:+)
::::::::::::::::::::::::::::::::::
QRS is related to ventricular contraction
This is because the ventricles followed by ventricles contraction.The depolarization is equal to the contraction for which QRS is related.
As it complexes downwards deflection of the triangular waves and it is passed to the downward waves.
Be bRaINly
---------------:+)
lol
hhahah
Answered by
2
The QRS complex is a name for the combination of three of the graphical deflections seen on a typical electrocardiogram (EKG or ECG). It is usually the central and most visually obvious part of the tracing; in other words, it's the main spike seen on an ECG line. It corresponds to the depolarization of the right and left ventricles of the human heart and contraction of the large ventricular muscles.
In adults, the QRS complex normally lasts 0.06–0.10 s; in children and during physical activity, it may be shorter. The Q, R, and S waves occur in rapid succession, do not all appear in all leads, and reflect a single event and thus are usually considered together. A Q wave is any downward deflection immediately following the P wave. An R wave follows as an upward deflection, and the S wave is any downward deflection after the R wave. The T wave follows the S wave, and in some cases, an additional U wave follows the T wave.
Formation Edit
See also: Electrical conduction system of the heart
Depolarization of the heart ventricles occurs almost simultaneously, via the bundle of His and Purkinje fibers. If they are working efficiently, the QRS complex is 80 to 120 ms in duration. This is represented by three small squares or less at the standard paper speed of 25 mm/s.
Clinical significance Edit
Any abnormality of conduction takes longer and causes "widened" QRS complexes. In bundle branch block, there can be an abnormal second upward deflection within the QRS complex. In this case, such a second upward deflection is referred to as R' (pronounced "R prime"). This would be described as an RSR' pattern.
Ventricles contain more muscle mass than the atria. Therefore, the QRS complex is considerably larger than the P wave. The QRS complex is often used to determine the axis of the electrocardiogram, although it is also possible to determine a separate P wave axis.
The duration, amplitude, and morphology of the QRS complex are useful in diagnosing cardiac arrhythmias, conduction abnormalities, ventricular hypertrophy, myocardial infarction, electrolyte derangements, and other disease states.
High frequency analysis of the QRS complex may be useful for detection of coronary artery disease during an exercise stress test.[1]
Components Edit
Schematic representation of the QRS complex.
Parameter Normal value Value comments Clinical significance
QRS duration 0.06–0.10 s[2] Shorter in children and in tachycardia[3] Prolonged duration indicates e.g. hyperkalemia.[4] or bundle branch block
QRS amplitude
S amplitude in V1 + R amplitude in V5 < 3.5 millivolt (mV)[3]
R+S in a precordial lead < 4.5 mV[3]
R in V5 or V6 < 2.6 mV
Increased amplitude indicates cardiac hypertrophy
Ventricular
activation
time (VAT)
< 0.05 s in V5 or V6[3]
< 0.03 s in V1[3]
Measured in increased QRS amplitude[3]
Q wave
Duration up to 0.04 seconds in leads other than III and aVR[5]
Amplitude less than 1/3 QRS amplitude[5] (R+S)
Amplitude less than 1/4 of R wave[5]
Abnormality indicates presence of infarction[5]
The QRS complex is also included in estimating the QT interval.
Q wave Edit
Normal Q waves, when present, represent depolarization of the interventricular septum. For this reason, they are referred to as septal Q waves and can be appreciated in the lateral leads I, aVL, V5 and V6.
Pathologic Q waves occur when the electrical signal passes through stunned or scarred heart muscle; as such, they are usually markers of previous myocardial infarctions, with subsequent fibrosis. A pathologic Q wave is defined as having a deflection amplitude of 25% or more of the subsequent R wave, or being > 0.04 s (40 ms) in width and > 2 mm in amplitude. However, diagnosis requires the presence of this pattern in more than one corresponding lead.
R wave progression Edit
Looking at the precordial leads, the R wave usually progresses from showing an rS-type complex in V1 with an increasing R and a decreasing S wave when moving toward the left side.
In adults, the QRS complex normally lasts 0.06–0.10 s; in children and during physical activity, it may be shorter. The Q, R, and S waves occur in rapid succession, do not all appear in all leads, and reflect a single event and thus are usually considered together. A Q wave is any downward deflection immediately following the P wave. An R wave follows as an upward deflection, and the S wave is any downward deflection after the R wave. The T wave follows the S wave, and in some cases, an additional U wave follows the T wave.
Formation Edit
See also: Electrical conduction system of the heart
Depolarization of the heart ventricles occurs almost simultaneously, via the bundle of His and Purkinje fibers. If they are working efficiently, the QRS complex is 80 to 120 ms in duration. This is represented by three small squares or less at the standard paper speed of 25 mm/s.
Clinical significance Edit
Any abnormality of conduction takes longer and causes "widened" QRS complexes. In bundle branch block, there can be an abnormal second upward deflection within the QRS complex. In this case, such a second upward deflection is referred to as R' (pronounced "R prime"). This would be described as an RSR' pattern.
Ventricles contain more muscle mass than the atria. Therefore, the QRS complex is considerably larger than the P wave. The QRS complex is often used to determine the axis of the electrocardiogram, although it is also possible to determine a separate P wave axis.
The duration, amplitude, and morphology of the QRS complex are useful in diagnosing cardiac arrhythmias, conduction abnormalities, ventricular hypertrophy, myocardial infarction, electrolyte derangements, and other disease states.
High frequency analysis of the QRS complex may be useful for detection of coronary artery disease during an exercise stress test.[1]
Components Edit
Schematic representation of the QRS complex.
Parameter Normal value Value comments Clinical significance
QRS duration 0.06–0.10 s[2] Shorter in children and in tachycardia[3] Prolonged duration indicates e.g. hyperkalemia.[4] or bundle branch block
QRS amplitude
S amplitude in V1 + R amplitude in V5 < 3.5 millivolt (mV)[3]
R+S in a precordial lead < 4.5 mV[3]
R in V5 or V6 < 2.6 mV
Increased amplitude indicates cardiac hypertrophy
Ventricular
activation
time (VAT)
< 0.05 s in V5 or V6[3]
< 0.03 s in V1[3]
Measured in increased QRS amplitude[3]
Q wave
Duration up to 0.04 seconds in leads other than III and aVR[5]
Amplitude less than 1/3 QRS amplitude[5] (R+S)
Amplitude less than 1/4 of R wave[5]
Abnormality indicates presence of infarction[5]
The QRS complex is also included in estimating the QT interval.
Q wave Edit
Normal Q waves, when present, represent depolarization of the interventricular septum. For this reason, they are referred to as septal Q waves and can be appreciated in the lateral leads I, aVL, V5 and V6.
Pathologic Q waves occur when the electrical signal passes through stunned or scarred heart muscle; as such, they are usually markers of previous myocardial infarctions, with subsequent fibrosis. A pathologic Q wave is defined as having a deflection amplitude of 25% or more of the subsequent R wave, or being > 0.04 s (40 ms) in width and > 2 mm in amplitude. However, diagnosis requires the presence of this pattern in more than one corresponding lead.
R wave progression Edit
Looking at the precordial leads, the R wave usually progresses from showing an rS-type complex in V1 with an increasing R and a decreasing S wave when moving toward the left side.
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