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Electrocardiography is the process of producing an electrocardiogram (ECG or EKG [a]), a recording of the heart's electrical activity through repeated cardiac cycles. [4] It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the heart [ 5 ] using electrodes placed on the skin.
Inverted T wave is considered abnormal if inversion is deeper than 1.0 mm. Inverted T waves found in leads other than the V1 to V4 leads is associated with increased cardiac deaths. Inverted T waves associated with cardiac signs and symptoms (chest pain and cardiac murmur) are highly suggestive of myocardial ischaemia. [4]
This sinus rhythm is important because it ensures that the heart's atria reliably contract before the ventricles, ensuring as optimal stroke volume and cardiac output. [ 4 ] In junctional rhythm, however, the sinoatrial node does not control the heart's rhythm – this can happen in the case of a block in conduction somewhere along the pathway ...
If at least three different shaped P waves can be seen in a given ECG lead tracing, this implies that even if one of them arises from the SA node, at least two others are arising elsewhere. This is taken as evidence of multiple (i.e. at least two) ectopic foci , and is called multifocal (or more correctly, multiform) atrial rhythm if the rate ...
Cardiac output as shown on an ECG. Cardiac output (CO) is a measurement of the amount of blood pumped by each ventricle (stroke volume, SV) in one minute. To calculate this, multiply stroke volume (SV), by heart rate (HR), in beats per minute. [1] It can be represented by the equation: CO = HR x SV [1]
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 ...
According to V. Gorshkov-Cantacuzene: "The U wave is the momentum carried by the blood in the coronary arteries and blood vessels". [4] [5] [6]The resistivity of stationary blood is expressed as () = | (+), where is a coefficient, and is the hematocrit; at that time, as during acceleration of the blood flow occurs a sharp decrease in the longitudinal resistance with small relaxation times.
Schematic representation of normal ECG In electrocardiography , the ST segment connects the QRS complex and the T wave and has a duration of 0.005 to 0.150 sec (5 to 150 ms). It starts at the J point (junction between the QRS complex and ST segment) and ends at the beginning of the T wave.