![]() In the instantaneous vector the left ventricle's thick muscularity plays a role, so the vector points to the left. From there, depolarization spreads through the Purkyne fibers to the working myocardium of the two ventricles, from the endocard to the epicard. In the next step the excitation spreads to the heart apex, the instantaneous vector points to the left down direction, forming the central part of the QRS complex, in most leads it is the R wave. In the ECG is either a negative Q, or a positive R wave, depending on the lead. The impulse progresses through the Hiss bundle and Tawar's arm to the muscles of the interventral septum, where depolarization spreads from left to right, thus the instantaneous vector directs right down. This is followed by depolarization of the ventricles, forming the QRS complex in the ECG record. In the ECG graph it is visible as an isoelectric line ( PR). Slow conduction in the atrioventricular node (AV) slows down the propagation of depolarization from the atria to the ventricles to separate the atrial systole from the ventricular systole. In the ECG record it appears to be the P wave. The instantaneous final vector has a relatively small amplitude due to the thin wall of the atrium, and is pointing left down. ![]() The myocardial action potential normally arises from spontaneous depolarization in the sinoatrial node (SA), from where it spreads to the atrial muscles. Represents SA, Atrium, AV (delay), BBB & Purkinje fibres. Simple representation of conduction through cardiac electrical pathways and myocardium. Under special circumstances, other leads may be used. Therefore the most common ECG electrocardiagram has currently 12-leads. Thus, we obtain additional 'Goldberger augmented' limb leads (aVR, aVL, aVF) and the thoracic (V1-V6) leads. They are called unipolar leads as the potential is always measured relative to a constant potential given by the average potential of the the RA, LA and LL potentials i.e., (RA + LA + LL)/3 called the Wilson potential), which is conventionally set as a reference zero potential. Today ECG measurement is improved by adding additional leads. The vector sum of all three amplitudes of these limbs is equal to zero (Einthoven's law). The leads then record the potential difference between the electrodes and indicate the resulting amplitude. The principle of these leads is the connection of two active electrodes whose polarity is predetermined. He used the three standard bipolar limb leads (I, II, III), still in use today, forming the so-called Einthoven triangle, in which the heart lies at the imaginary centroid. The capture of these potentials was introduced by the Dutch physiologist Willem Einthoven in the early 20th century. The myocardial potential spreads from the heart to the surface of the body as body tissues and fluids are good conductors of electricity. endocrine disease: diseases of the thyroid gland ( hypothyroidism and hyperthyroidism).metabolic disease: hypocalcemia or hypercalcemia, hypokalemia or hyperkalemia.heat disease: heart attack, arrhythmias, conduction disturbances, myocardial ischemia.However, the ECG examination on it's own is not enough to produce a complete diagnosis.ĮCG is indicated if there is suspicion onf In addition, we can detect disturbances arising from extra-cardiac causes (eg. Since the electrical activity of the heart is very important for its mechanical activity, the ECG has an important diagnostic role in a number of heart diseases. However it is also possible to measure the ECG from the esophagus wall or right on the heart's surface. ECG examinations are mostly non-invasive using electrodes placed on the skin. ![]() It monitors the heart's electrical activity (as an electrocardiogram) as measured from the surface of the body and allows its evaluation. The timestamp is only as accurate as the clock in the camera, and it may be completely wrong.Electrocardiography (ECG/EKG) is the basic diagnostic method in cardiology. If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file. This file contains additional information such as Exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it. ![]()
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