Electrocardiography

(ECG, EKG)

The standard ECG 12 provides various derivatives of the cardiac electrical activity that reflect the electrical potential differences between positive and negative electrodes; the electrodes are placed at the extremities and the chest wall. Six of these derivatives are arranged perpendicularly (they use frontal leads I, II and III as well as limb leads aVR, aVL and aVF), six are arranged horizontally (precordial leads V1, V2, V3, V4, V5 and V6). The 12-lead ECG is crucial to provide many cardiac diagnoses see Table: Interpretation abnormal EKGs), including arrhythmias Myocardial Atrial Enlargement Left ventricular hypertrophy (see Table: Criteria for the ECG diagnosis of left ventricular hypertrophy) circumstances that one to syncope or sudden cardiac death predispose (z. B. Wolff-Parkinson-White syndrome, long QT syndrome, Brugada syndrome). More information on the ECG evaluation, see Overview of arrhythmias, diagnosis and ECG in acute coronary syndrome. A useful ECG tutorial is available from the University of Utah. Clinical calculator: Romhilt-Estes criteria for left ventricular hypertrophy interpretation abnormal ECG Abnormal Component Description Possible causes P-waves Abnormal left or right atrial hypertrophy, atrial escape (ectopic) -Schläge P-waves Missing atrial fibrillation, sinus arrest or -Exit- block, hyperkalemia (severe) PP interval Varying sinus arrhythmia PR interval long AV block first degree PR interval Varying Mobitz type I AV block, multifocal atrial tachycardia fibrillation wide QRS complex left or right bundle branch block, or Kammerflattern-, hyperkalemia QT interval Long Myocardial infarction, myocarditis, hypocalcemia, hypokalemia, hypomagnesemia, hypothyroidism, subarachnoid or Intrazerebralblutung, stroke, congenital long QT syndrome, antiarrhythmic drugs (eg. B. sotalol, amiodarone, quinidine), tricyclic antidepressants, phenothiazines, other substances QT interval short hypercalcemia, hypermagnesemia, Graves’ disease, digoxin ST-segment depression myocardial ischemia; acute posterior myocardial infarction, digoxin; ventricular hypertrophy; Pulmonary embolism; left bundle branch block, right bundle branch block in lines V1-V3 and possibly in II, III, and aVF; Hyperventilation; Hypokalemia ST-segment elevation myocardial ischemia, acute myocardial infarction, left bundle branch block, acute pericarditis, left ventricular hypertrophy, hyperkalemia, pulmonary embolism, digoxin, normal variation (z. B. athlete’s heart), hypothermia T-wave high hyperkalemia, acute myocardial infarction, left bundle branch block, stroke, ventricular hypertrophy link sven T wave small, flat or inverted myocardial ischemia, myocarditis, age, race, hyperventilation, anxiety, drinking hot or cold drinks, trikuläre hypertrophy, certain medications (eg. Digoxin), pericarditis, pulmonary embolism, cardiac conduction disorders (eg. B. right bundle branch block), electrolyte disturbances (z. B. hypokalemia) U wave Prominent hypokalemia, hypomagnesemia, ischemia criteria for ECG diagnosis of left ventricular hypertrophy criterion finding points Romhilt -Estes (5 points = definitely LVH; 4 points = probably LVH) R o the S-wave ?20 mm in each limb lead or S-wave in V1 or V2?30 mm or R-wave in V5 or V6?30 3 mm ST-T changes typical of LVH – Digitalis 1 3 No Digitalis left atrial changes: P-terminal shaft in V1, amplitude and duration ?1 mm ?0,04 s 3 left Ac hsenabweichung ?-30 ° 2 QRS duration ?90 1 msec QRS interval between R-waves and high point in V5 or V6?0,05 s 1 Sokolov-Lyon V1 + S-wave V5 or V6 R-wave ?35 mm or aVL R -wave ?11 mm N / A – Cornell men: V3 S wave + aVL R wave> 28 mm N / A Women: V3 S wave + aVL R-Wel le> 20 mm N / A LVH = left ventricular hypertrophy. Standard ECG components of the ECG recording in the P-wave, the PR interval, the QRS complex, the QT interval, ST-segment, the T-wave and U-wave is convention divided (ECG waves .). ECG waves. P-wave = atrial activation (depolarization). PR interval = time interval between the onset of atrial depolarization and the beginning of ventricular depolarization. QRS complex = depolarization of the ventricles, consisting of Q, R and S waves. QT interval = time interval between the start of ventricular depolarization and the end of ventricular repolarization. R-R interval = time interval between two QRS complexes. T wave = ventricular repolarization. ST segment plus the T wave (ST-T) = ventricular repolarization. U wave may Nachdepolarisation = (relaxation) of the ventricles. P-wave, the P-wave represents the atrial depolarization. It is positive in most leads except in aVR. You may be biphasic in leads II and V1. The initial component represents the right atrial activity and the 2nd fraction, the left atrial activity. An increase in the amplitude of one or both components is created with the atrial magnification. A right-magnification causes a P wave> 2 mm in leads II, III, and aVF (P pulmonale); a left side atrial enlargement resulting in a broad and doppelgipfligen P-wave in lead II (P mitral). Normally, the P-axis is between 0 ° and 75 ° .PR interval The PR interval is the time duration between the beginning of the atrial depolarization and the start of ventricular depolarization. Usually it takes 0.10 to 0.20 seconds; a prolongation of PR-interval defines the degree AV block I.QRS complex The QRS complex represents the ventricular depolarization. The Q wave is the initial downward movement. Normal Q waves take <0.05 sec in all leads except V1-3 in which each Q-wave is considered abnormal and indicates a past or ongoing myocardial infarction. The R-wave is the first upward movement. The criteria for normal height or size are not to be regarded as absolute, but higher R-waves can be caused by ventricular hypertrophy. 2. An upward movement within a QRS complex is called R '. The S-wave is the second downward movement when a Q wave precedes, and the first downward movement if this is not the case. The QRS complex can consist of a R alone, the QS (without R), the QR (without S), the RS (not Q) or the RSR consist ', depending on a particular from the ECG, the heart vector and the presence heart disease. Normally, the QRS interval is from 0.07 to 0.10 seconds. An interval of 0.10-0.11 seconds is considered to be incomplete bundle branch block or as a non-specific intraventricular conduction delay as a function of the QRS morphology. An interval ? 0.12 s is regarded as a complete bundle branch block or intraventricular conduction delay considered. Normally, the QRS-axis is 90 ° to -30 °. An axis of -30 ° to -90 ° is referred to as links deviation of the axis of the heart and at linksanteriorem hemiblock inferiorem and myocardial infarction observed (-60 °). A heart axis of 90 ° to 180 ° is described as a right deviation of the axis of the heart. This occurs in any condition which leads to increased pulmonary artery pressures or to a right ventricular hypertrophy (cor pulmonale, acute pulmonary embolism, pulmonary arterial pressure) and sometimes occurs at right bundle branch block or linksposteriorem fascicular block auf.QT interval The QT interval is the time between the onset of ventricular depolarization and the end of ventricular repolarization. The QT interval must be corrected for heart rate using a formula: where QTc is the corrected QT interval, and R-R interval is the time between two QRS complexes. All intervals are specified in seconds. QTc prolongation is heavily involved in the development of ventricular tachycardia of the type torsade de pointes. QTc is often difficult to calculate, because the exact end of the T-wave is often unclear or is followed by a U-shaft, with which it can merge. Numerous drugs are in the prolongation of the QT interval involved (s. QTdrugs.org). Clinical calculator: QT interval correction (ECG) ST segment The ST segment represents the complete ventricular Myokarddepolarisation. Usually, it extends horizontally along the base line of the PR (or TP) interval or slightly deviating therefrom. An ST segment elevation can be caused by early repolarization Left ventricular hypertrophy myocardial ischemia and infarction left ventricular aneurysm pericarditis hyperkalemia hypothermia pulmonary embolism An ST segment depression can be caused by hypokalemia digoxin subendocardial ischemia reciprocal changes in acute myocardial infarction T-wave, the T wave reflects the ventricular repolarization. It usually has the same direction as the QRS complex (concordant). The opposite polarity (discordant) can display an old or current infarction. The T wave is usually soft and rounded, but can at a hypokalemia and hypomagnesemia have a low amplitude and greater at a hyperkalemia, hypocalcemia and left ventricular hypertrophy and acute sein.U wave the U wave rarely occurs in patients with hypokalemia, hypomagnesemia or ischemia. They often occurs in healthy people. Specialized ECG tests A standard 12-lead ECG shows only a single brief period of cardiac activity. Improved techniques can provide additional information. Additional precordial leads Additional precordial leads are used to a right ventricular infarction and a Hinterwandimyokardinfarkt to diagnose. Right-sided derivatives are applied on the right side of the chest addition, in order to mimic the standard left derivatives. They are called V1R to V6R; sometimes V4R is used, as this is most sensitive to the right ventricular myocardial infarction. Additional left-sided leads can be placed in the fifth intercostal space, with V7 on the posterior axillary line, V8 on the middle shoulder blade line and V9 at the left edge of the spine. These lines are rarely used, but an oesophageal dissipation is much closer to the courts than the surface discharges in the diagnosis of a true posterior MIyokardinfarkts helfen.Ösophageale dissipation. therefore, it represents an option if the presence of P-waves in the standard ECG is uncertain and when the detection of atrial electrical activity is important, as if an atrial or ventricular tachycardia should be differentiated or if an AV dissociation is suspected. An esophageal can also be used for monitoring an intra-operative myocardial ischemia, or for detecting atrial activity during cardioplegia. The derivative is characterized placed that the patient swallows the electrode which is connected to a standard ECG device, often in the port for derivation II.Signalmittelung The signal averaging of QRS complexes causes a digital summary of hundreds of cardiac cycles to high frequency potentials with to detect low amplitude and micro currents at the terminal end of the QRS complex. These findings represent areas with slow conduction through the abnormal myocardium and show an increased risk of ventricular reentrant tachycardia on. The signal-mediated ECG is still largely a research technique, but is sometimes used to assess the risk of sudden cardiac death (eg. As in patients with known significant heart disease). It seems very useful in identifying patients with low risk of sudden death. Their value for identifying patients at high risk for sudden death has not yet been proven. Signal averaging is also being investigated for various other heart diseases, beginning to assess up to Brugada syndrome and ventricular aneurysms, and the effectiveness of operations, correct the arrhythmia of the state in post-myocardial infarction and cardiomyopathy. This technique can also be very helpful to determine proarrhythmogene medication effects and to detect the rejection of transplanted hearts. The signal averaging of P waves is currently being studied as a way to identify patients at increased risk of atrial fibrillation to erkennen.Kontinuierliche ST segment monitoring this type of monitoring is used for early detection of ischemia and severe arrhythmias. Monitoring can be automated (special electronic monitor systems are available for this purpose) are clinically performed by serial ECG or letters. The applications in the ICU close monitoring of patients with crescendo angina pectoris, rate percutaneous surgery and intraoperative monitoring and postoperative care with ein.QT scattering the QT dispersion (the difference between the longest and shortest QT interval in the 12-channel -EKG) was proposed as a measure of the heterogeneity of myocardial repolarization. An enhanced scattering (? 100 ms) suggests an electrically heterogeneous myocardium, which is caused by ischemia or fibrosis, with an increased risk of reentry arrhythmias and sudden cardiac death. The QT dispersion estimated mortality risks, but is not widely used because the measurement errors are common, the measured values ??in patients with and significantly overlap without disease, there are no clear benchmarks and other validated risk predictors sind.Herzfrequenzvariabilität available This measurement reflects the balance between sympathetic and parasympathetic (vagal) resist at heart. Decreased variability suggests a reduced vagal activity and increased sympathetic tone, which predicts an increased risk of arrhythmias and mortality. The most common measure of the variability of the average standard deviation of all normal R-R intervals in the 24-hour ECG recording. Heart rate variability is primarily studied scientifically, but there are evidences that they are useful information on left ventricular dysfunction after myocardial infarction, heart failure and hypertrophic cardiomyopathy. Most long-time monitors have software that measures the heart rate variability and analysiert.Langzeit monitor A long-term monitoring is continuous monitoring and taking ECG, blood pressure, or both on for 24 or 48 h. It is useful for the evaluation of intermittent arrhythmias and secondarily for the detection of high blood pressure. The long-term monitor is portable and allows patients to carry out their normal daily activities. It can also be used for sitting, stationary lying patients when an automatic monitoring is not available. Patients are asked to write down their symptoms and activities so that they can be correlated with the events on the screen. The long-term monitor does not automatically analyzes the ECG data. A doctor does this at a later date durch.Ereignissrekorder event recorder be worn for up to 30 days and can detect infrequent arrhythmias, which could not be detected in the 24-hour Holter monitoring. The recorder can operate continuously and are activated by the patient when symptoms occur. A storage mode allows to record the information for a few seconds or minutes before and after activation. The patient can transmit ECG data via phone or satellite, which is read by a doctor; Some recorder automatically transmit serious incidents. When patients severe events (eg. As syncope) have at intervals of> 30 days, an event recorder can be implanted subcutaneously (implantable memory recorder). It can then be activated by a small magnet. The battery life for subcutaneous recorders is 36 months. “Wireless adhesive monitor” A new option for a single-channel rhythm monitor is a small, adhesive, waterproof and wireless to outstanding on chest instrument. One type of this apparatus continuously records on heart rhythms for up to 2 weeks. Another similar device acts as an event recorder; a patient pushes a button on the device when eirgendwelche arrhythmia symptoms (eg. B. palpitations, dizziness) to record the stored ECG data 45 seconds before the event to 15 seconds after the event. However, unlike event recorders, an automated real-time reporting is not available. More information University of Utah ECG Learning Center CredibleMeds QTDrugs Lists

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