2018年9月22日土曜日

What causes AF?

What causes AF? Some medical conditions increase your chances of developing AF. These include heart problems such as coronary heart disease, or disease of your heart’s valves. It can also be caused by other conditions including an overactive thyroid gland, high blood pressure, lung infections like pneumonia, or a blood clot in the lung (pulmonary embolism). Drinking too much alcohol or caffeine, taking illegal drugs, such as cocaine or amphetamines, or smoking can also trigger an episode of AF. What are the symptoms? Palpitations (being aware of your heart beating fast), breathlessness, chest pain or fatigue are common symptoms of AF. However, some people do not have any symptoms at all and AF is often only diagnosed during a general medical check-up. The four different types of AF are: • paroxysmal AF comes and goes – it’s not there all the time. Your heart goes back to its normal rhythm without any treatment, usually within 48 hours • persistent AF is where you have AF episodes that last more than seven days and it is unlikely that they will stop on their own. You may need treatment to restore your normal heart rhythm • long-standing persistent AF means you have had continuous atrial fibrillation for a year or longer • permanent AF is there all the time. You might be diagnosed with permanent AF if you’ve had it for more than one year and treatment with cardioversion hasn’t helped. How is AF diagnosed? AF can be detected by a healthcare professional checking your pulse. If your pulse feels very fast and/or irregular, they may refer you for further tests to confirm whether you have AF, and if so, what type you have. AF that comes and goes can be hard to detect. To help diagnose it, you may be asked to wear a portable ECG monitor for 24 hours or more to check how your heart works over a longer period of time. This option is available in the Cardiospy ECG Holter system Detection of P wave in ECG Holter technique is a complex and difficult task as these waves are very small amplitude signals. In addition to sampling the ECG signal at a high amplitude resolution, quite strong disturbances make it difficult to detect this signal. The Cardiospy system simultaneously provides high amplitude resolution, efficient interference filtering, and reliable P wave detection. Algorithm of diseases based on the P wave detection in the Cardiospy Holter software Cardiospy software uses P wave analysis to detect AV blocks (AV-I, AV-II-M1, AV-II-M2, AV-III) and Atrial Fibrillation. This algorithm is developed by our colleague, Mr. László Farkas R/D manager, who has been working with digital signal processing for more than 30 years. Technical conditions of P wave detection To detect P waves, it needs high amplitude resolution, which is provided by the recorders of the Cardiospy system. The amplitude resolution is better than 0.6uV, which can even detect a few 10uV P waves. Good resolution is not enough, however, because very small P waves can be covered or distorted by minor noise. The Cardiospy filter system ensures that the P waves are displayed clearly.

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