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In a 12-lead ECG, all leads except the limb leads are assumed to be unipolar (aVR, aVL, aVF, V 1, V 2, V 3, V 4, V 5, and V 6). The measurement of a voltage requires two contacts and so, electrically, the unipolar leads are measured from the common lead (negative) and the unipolar lead (positive).
This helps to prevent ventricular channel oversensing of atrial output. Newer dual chamber pacemakers also use bipolar leads with a smaller pacing spike, and steroid eluting leads with lower pacing thresholds. Crosstalk is more common in unipolar systems since they require a larger pacing spike.
Einthoven's triangle is an imaginary formation of three limb leads in a triangle used in the electrocardiography, formed by the two shoulders and the pubis. [1] The shape forms an inverted equilateral triangle with the heart at the center. It is named after Willem Einthoven, who theorized its existence. [2]
The bundle of His (BH) [1]: 58 or His bundle (HB) [1]: 232 (/ h ɪ s / "hiss" [2]) is a collection of heart muscle cells specialized for electrical conduction.As part of the electrical conduction system of the heart, it transmits the electrical impulses from the atrioventricular node (located between the atria and the ventricles) to the point of the apex of the fascicular branches via the ...
The hexaxial reference system is a diagram that is used to determine the heart's electrical axis in the frontal plane. The hexaxial reference system, better known as the Cabrera system, is a convention to present the extremity leads of the 12 lead electrocardiogram, [1] that provides an illustrative logical sequence that helps interpretation of the ECG, especially to determine the heart's ...
For some pacing leads, both connections to the heart are provided in a single lead ("bipolar") and some only provide a single connection ("unipolar"). In unipolar, the second connection is internally from the heart to the generator through the body (blood, tissue, etc). Also important is the impedance. The lower the impedance, the more current ...
The heart is a muscular organ situated in the mediastinum.It consists of four chambers, four valves, two main arteries (the coronary arteries), and the conduction system. The left and right sides of the heart have different functions: the right side receives de-oxygenated blood through the superior and inferior venae cavae and pumps blood to the lungs through the pulmonary artery, and the left ...
In the pacemaking cells of the heart (e.g., the sinoatrial node), the pacemaker potential (also called the pacemaker current) is the slow, positive increase in voltage across the cell's membrane, that occurs between the end of one action potential and the beginning of the next.