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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.
A right bundle branch block typically causes prolongation of the last part of the QRS complex and may shift the heart's electrical axis slightly to the right. The ECG will show a terminal R wave in lead V1 and a slurred S wave in lead I. Left bundle branch block widens the entire QRS, and in most cases shifts the heart's electrical axis to the ...
The two bundle branches taper out to produce numerous Purkinje fibers, which stimulate individual groups of myocardial cells to contract. [5] The spread of electrical activity through the ventricular myocardium produces the QRS complex on the ECG. Atrial repolarization occurs and is masked during the QRS complex by ventricular depolarization on ...
The cardiovascular centre affects changes to the heart rate by sending a nerve impulse to the cardiac pacemaker via two sets of nerves: sympathetic fibres, part of the autonomic nervous system, to make heart rate faster. the vagus nerve, part of the parasympathetic branch of the autonomic nervous system, to lower heart rate.
An unusually tall QRS complex may represent left ventricular hypertrophy while a very low-amplitude QRS complex may represent a pericardial effusion or infiltrative myocardial disease. 80 to 100 ms J-point: The J-point is the point at which the QRS complex finishes and the ST segment begins. The J-point may be elevated as a normal variant.
The Pan–Tompkins algorithm [1] is commonly used to detect QRS complexes in electrocardiographic signals . The QRS complex represents the ventricular depolarization and the main spike visible in an ECG signal (see figure).
When an individual is in normal sinus rhythm, the ECG characteristics of WPW are a short PR interval (less than 120 milliseconds in duration), widened QRS complex (greater than 120 milliseconds in duration) with slurred upstroke of the QRS complex, and secondary repolarization changes (reflected in ST segment-T wave changes). [citation needed]
Second-degree atrioventricular block (AV block) is a disease of the electrical conduction system of the heart.It is a conduction block between the atria and ventricles.The presence of second-degree AV block is diagnosed when one or more (but not all) of the atrial impulses fail to conduct to the ventricles due to impaired conduction.