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Diagram showing how the polarity of the QRS complex in leads I, II, and III can be used to estimate the heart's electrical axis in the frontal plane. The QRS complex is the combination of three of the graphical deflections seen on a typical electrocardiogram (ECG or EKG). It is usually the central and most visually obvious part of the tracing.
During atrial ectopic activity where the P wave is normally rounded can be inverted or peaked. However the QRS complex and T waves appear relatively normal. [10] Conversely, during junctional ectopic activity the P wave is frequently absent or can be hidden in the QRS complex. [11]
The T wave can be described by its symmetry, skewness, slope of ascending and descending limbs, amplitude and subintervals like the T peak –T end interval. [1] In most leads, the T wave is positive. This is due to the repolarization of the membrane. During ventricle contraction (QRS complex), the heart depolarizes.
The QRS complex represents the conduction of the ventricles of the heart, the speed at which they are able to conduct an electrical impulse. The interval between each R wave represents the heart rate, which is critical for determining different rhythms within the defined categories.
Electrical waves track a systole (a contraction) of the heart. The end-point of the P wave depolarization is the start-point of the atrial stage of systole. The ventricular stage of systole begins at the R peak of the QRS wave complex; the T wave indicates the end of ventricular contraction, after which ventricular relaxation (ventricular diastole) begins.
In order to detect a QRS complex, the local peaks of the integrated signal are found. A peak is defined as the point in which the signal changes direction (from an increasing direction to a decreasing direction). After each peak, no peak can be detected in the next 200 ms (i.e. the lockout time).
R peak, also written as R-peak and Rpeak, could refer to: In the QRS complex of an electrocardiogram it refers to the maximum amplitude in the R wave In the high performance LINPACK benchmarks of supercomputers it refers to the theoretical peak performance of the system
In the electrocardiogram, the intrinsicoid deflection is the downstroke of the QRS complex, from its highest amplitude until it reaches the baseline or lower. [1] Since the ventricles normally depolarize from inside to outside, this deflection reflects the depolarization vector from the endocardium to the epicardium.