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To measure the QRS interval start at the end of the PR interval (or beginning of the Q wave) to the end of the S wave. Normally this interval is 0.08 to 0.10 seconds. When the duration is longer it is considered a wide QRS complex.
ECG beat. 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).
The Purkinje fibers, named for Jan Evangelista Purkyně, (English: / p ɜːr ˈ k ɪ n dʒ i / pur-KIN-jee; [1] Czech: [ˈpurkɪɲɛ] ⓘ; Purkinje tissue or subendocardial branches) are located in the inner ventricular walls of the heart, [2] just beneath the endocardium in a space called the subendocardium.
Three criteria are included in Sgarbossa's criteria: [2] ST elevation ≥1 mm in a lead with a positive QRS complex (i.e.: concordance) - 5 points; concordant ST depression ≥1 mm in lead V1, V2, or V3 - 3 points; ST elevation ≥5 mm in a lead with a negative (discordant) QRS complex - 2 points
The cardiac cycle is the performance of the human heart from the beginning of one heartbeat to the beginning of the next. [1] It consists of two periods: one during which the heart muscle relaxes and refills with blood, called diastole, following a period of robust contraction and pumping of blood, called systole. [1]
A criterion for sinus rhythm is that P waves and QRS complexes appear 1-to-1, thus implying that the P wave causes the QRS complex. [50] Once sinus rhythm is established, or not, the second question is the rate. For a sinus rhythm, this is either the rate of P waves or QRS complexes since they are 1-to-1.
The sinus node should pace the heart – therefore, P waves must be round, all the same shape, and present before every QRS complex in a ratio of 1:1. Normal P wave axis (0 to +75 degrees) Normal PR interval, QRS complex and QT interval. QRS complex positive in leads I, II, aVF and V3–V6, and negative in lead aVR. [3]
An idioventricular rhythm is a cardiac rhythm characterized by a rate of <50 beats per minute (bpm), absence of conducted P waves and widening of the QRS complex. [1] In cases where the heart rate is between 50 and 110 bpm, it is known as accelerated idioventricular rhythm and ventricular tachycardia if the rate exceeds 120 bpm.