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PR Interval
In electrocardiography, the PR interval is the period, measured in milliseconds, that extends from the beginning of the P wave (the onset of atrial depolarization) until the beginning of the QRS complex (the onset of ventricular depolarization); it is normally between 120 and 200 ms in duration. The PR interval is sometimes termed the PQ interval. Interpretation Variations in the PQ interval can be associated with certain medical conditions: * Duration ** A long PR interval (of over 200 ms) indicates a slowing of conduction between the atria and ventricles, usually due to slow conduction through the atrioventricular node (AV node). This is known as first degree heart block. Prolongation can be associated with fibrosis of the AV node, high vagal tone, medications that slow the AV node such as beta-blockers, hypokalemia, acute rheumatic fever, or carditis associated with Lyme disease. ** A short PR interval (of less than 120ms) may be associated with a Pre-excitation synd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acute Rheumatic Fever
Rheumatic fever (RF) is an inflammatory disease that can involve the heart, joints, skin, and brain. The disease typically develops two to four weeks after a streptococcal throat infection. Signs and symptoms include fever, multiple painful joints, involuntary muscle movements, and occasionally a characteristic non-itchy rash known as erythema marginatum. The heart is involved in about half of the cases. Damage to the heart valves, known as rheumatic heart disease (RHD), usually occurs after repeated attacks but can sometimes occur after one. The damaged valves may result in heart failure, atrial fibrillation and infection of the valves. Rheumatic fever may occur following an infection of the throat by the bacterium ''Streptococcus pyogenes''. If the infection is left untreated, rheumatic fever occurs in up to three percent of people. The underlying mechanism is believed to involve the production of antibodies against a person's own tissues. Due to their genetics, some peo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart Electrical Conduction System (PQ Segment)
The heart is a muscular organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrients to the tissue, while carrying metabolic waste such as carbon dioxide to the lungs. In humans, the heart is approximately the size of a closed fist and is located between the lungs, in the middle compartment of the chest, called the mediastinum. In humans, the heart is divided into four chambers: upper left and right atria and lower left and right ventricles. Commonly, the right atrium and ventricle are referred together as the right heart and their left counterparts as the left heart. In a healthy heart, blood flows one way through the heart due to heart valves, which prevent backflow. The heart is enclosed in a protective sac, the pericardium, which also contains a small amount of fluid. The wall of the heart is made up of three layers: epicardium, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pericarditis
Pericarditis () is inflammation of the pericardium, the fibrous sac surrounding the heart. Symptoms typically include sudden onset of sharp chest pain, which may also be felt in the shoulders, neck, or back. The pain is typically less severe when sitting up and more severe when lying down or breathing deeply. Other symptoms of pericarditis can include fever, weakness, palpitations, and shortness of breath. The onset of symptoms can occasionally be gradual rather than sudden. The cause of pericarditis often remains unknown but is believed to be most often due to a viral infection. Other causes include bacterial infections such as tuberculosis, uremic pericarditis, heart attack, cancer, autoimmune disorders, and chest trauma. Diagnosis is based on the presence of chest pain, a pericardial rub, specific electrocardiogram (ECG) changes, and pericardial effusion, fluid around the heart. A heart attack may produce similar symptoms to pericarditis. Treatment in most cases is with NSA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart Block
Heart block (HB) is a disorder in the heart's rhythm due to a fault in the natural pacemaker. This is caused by an obstruction – a block – in the electrical conduction system of the heart. Sometimes a disorder can be inherited. Despite the severe-sounding name, heart block may cause no symptoms at all in some cases, or occasional missed heartbeats in other cases (which can cause light-headedness, syncope (fainting), and palpitations), or may require the implantation of an artificial pacemaker, depending upon exactly where in the heart conduction is being impaired and how significantly it is affected. Heart block should not be confused with other conditions, which may or may not be co-occurring, relating to the heart and/or other nearby organs that are or can be serious, including angina (heart-related chest pain), heart attack (myocardial infarction), any type of heart failure, cardiogenic shock or other types of shock, different types of abnormal heart rhythms (arrhythm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Junctional Rhythm
Junctional rhythm also called nodal rhythm describes an abnormal heart rhythm resulting from impulses coming from a locus of tissue in the area of the atrioventricular node (AV node), the "junction" between atria and ventricles. Under normal conditions, the heart's sinoatrial node (SA node) determines the rate by which the organ beats – in other words, it is the heart's "pacemaker". The electrical activity of sinus rhythm originates in the sinoatrial node and depolarizes the atria. Current then passes from the atria through the atrioventricular node and into the bundle of His, from which it travels along Purkinje fibers to reach and depolarize the ventricles. 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. 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 alo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atrioventricular Reentrant Tachycardia
Atrioventricular reentrant tachycardia (AVRT), or atrioventricular reciprocating tachycardia, is a type of heart arrhythmia with an abnormally fast rhythm (tachycardia); it is classified as a type of supraventricular tachycardia (SVT). AVRT is most commonly associated with Wolff–Parkinson–White syndrome, but is also seen in permanent junctional reciprocating tachycardia (PJRT). In AVRT, an accessory pathway allows electrical signals from the heart's Ventricle (heart), ventricles to enter the Atrium (heart), atria and cause earlier than normal contraction, which leads to repeated stimulation of the atrioventricular node.Josephson ME. Preexcitation syndromes. In: Clinical Cardiac Electrophysiology, 4th, Lippincott Williams & Wilkins, Philadelphia 2008. p.339 Signs and symptoms An episode of SVT may present with palpitations, dizziness, Dyspnea, shortness of breath, or Syncope (medicine), losing consciousness (fainting). The electrocardiogram, electrocardiogram (ECG) would app ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lown–Ganong–Levine Syndrome
Lown–Ganong–Levine syndrome (LGL) is a pre-excitation syndrome of the heart. Those with LGL syndrome have episodes of abnormal heart racing with a short PR interval and normal QRS complexes seen on their electrocardiogram when in a normal sinus rhythm. LGL syndrome was originally thought to be due to an abnormal electrical connection between the atria and the ventricles, but is now thought to be due to accelerated conduction through the atrioventricular node in the majority of cases. The syndrome is named after Bernard Lown, William Francis Ganong, Jr., and Samuel A. Levine. Signs and symptoms In general, patients will be asymptomatic at baseline. During their tachyarrhythmia however, they may report palpitations, shortness of breath, syncope or presyncope. They will have a tachycardia. How well they tolerate their tachyarrhythmia is dictated by their physiologic reserve. A young, well patient may just have palpitations and the tachycardia alone. However, an older patie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wolff–Parkinson–White Syndrome
Wolff–Parkinson–White syndrome (WPWS) is a disorder due to a specific type of problem with the electrical system of the heart involving an accessory pathway able to conduct electrical current between the atria and the ventricles, thus bypassing the atrioventricular node. About 60% of people with the electrical problem develop symptoms, which may include an abnormally fast heartbeat, palpitations, shortness of breath, lightheadedness, or syncope. Rarely, cardiac arrest may occur. The most common type of arrhythmia (abnormal heart rate) associated with WPWS is paroxysmal supraventricular tachycardia. The cause of WPW is typically unknown and is likely due to a combination of chance and genetic factors. A small number of cases are due to a mutation of the PRKAG2 gene which may be inherited in an autosomal dominant fashion. The underlying mechanism involves an accessory electrical conduction pathway between the atria and the ventricles. It is associated with other cond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pre-excitation Syndrome
Pre-excitation syndrome is a heart condition in which part of the cardiac ventricles are activated too early. Pre-excitation is caused by an abnormal electrical connection or accessory pathway between or within the cardiac chambers. Pre-excitation may not cause any symptoms but may lead to palpitations caused by abnormal heart rhythms. It is usually diagnosed using an electrocardiogram, but may only be found during an electrophysiological study. The condition may not require any treatment at all, but symptoms can be controlled using medication or catheter ablation. Types Several types of pre-excitation syndrome have been described. Pathophysiology Normally, the atria and the ventricles are electrically isolated, and electrical contact between them exists only at the "atrioventricular node". In all pre-excitation syndromes, at least one more conductive pathway is present. Physiologically, the normal electrical depolarization wave is delayed at the atrioventricular node ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lyme Disease
Lyme disease, also known as Lyme borreliosis, is a tick-borne disease caused by species of ''Borrelia'' bacteria, Disease vector, transmitted by blood-feeding ticks in the genus ''Ixodes''. It is the most common disease spread by ticks in the Northern Hemisphere. Infections are most common in the spring and early summer. The most common sign of infection is an expanding red rash, known as erythema migrans (EM), which appears at the site of the tick bite about a week afterwards. The rash is typically neither itchy nor painful. Approximately 70–80% of infected people develop a rash. Other early symptoms may include fever, headaches and fatigue (medical), tiredness. If untreated, symptoms may include Facial nerve paralysis, loss of the ability to move one or both sides of the face, arthritis, joint pains, Meningitis, severe headaches with neck stiffness or heart palpitations. Months to years later, repeated episodes of joint pain and swelling may occur. Occasionally, shootin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carditis
Carditis (pl. carditides) is the inflammation of the heart. It is usually studied and treated by specifying it as: * Pericarditis is the inflammation of the pericardium * Myocarditis is the inflammation of the heart muscle * Endocarditis is the inflammation of the endocardium * Pancarditis, also called perimyoendocarditis, is the inflammation of the entire heart: the pericardium, the myocardium and the endocardium * Reflux carditis refers to a possible outcome of esophageal reflux (also known as GERD Gastroesophageal reflux disease (GERD) or gastro-oesophageal reflux disease (GORD) is a chronic upper gastrointestinal disease in which stomach content persistently and regularly flows up into the esophagus, resulting in symptoms and/or ...), and involves inflammation of the esophagus/stomach mucosa References Heart diseases {{circulatory-disease-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
