P波検出能は、循環器の世界を揺るがす話題になる可能性が見える、 ホルター心電計を長期間装着することには一般的には無理がある、 又、高額なバッテリーが必要になる、又、P波や心房細動検出が24時間で 検出出来ないだけで大掛かりな装置が必要になる、 又、たった一チャンネル心電図と狭い電極間隔できちんと検出できるのか？ ノイズや態動との区別はできるのか？ 今迄のホルターでは、P波を検出できていない為ではないか？ との疑念がある、 検査技師や臨床工学技師やホルターを長年関わってきた専門営業マンらは、 皆一様に、目視で判ると仰っている、其処で疑念が湧いてくる、 目視で判る患者では、相当悪化しているからで、偶にしか症状の出ない 症例では目視で見付けるのは、至難の技ではないか、 そして、当該疾患の関わる範囲は広いので、広大な予防医学の分野ではないか、 突然死や、自律神経失調や、ガン関連疾患や、脳血管とか肺血管梗塞や、 ペースメーカ関係疾患に深く関係しているように思われる、
Validation of P wave detection The result rate of Cardiospy algorithms is determined by testing on a reference database, thus validating the P wave detection algorithm. The reference database contains typical P wave occurrences: small and large amplitudes, mono and biphasic, narrow and wide, short and long PQ distances. The result of the algorithm is: Se = 95.42%, Pp = 97.16%. (Se = Sensitivity; Pp = Positive predictivity) Validation of disease types associated with P wave detection The Cardiospy system uses the P wave analysis to detect various AV blocks and Atrial Fibrillation. Similarly to the P wave detection, determination of the result ratio of AV blocks and Atrial Fibrillation analyses is also performed by reference to a reference database. The reference databases consist of some of the representative records collected from MitBih (AF) database and partly by Labtech Ltd. Result of algorithms: Se[%] Pp[%] AF 96.46 98.71 AV-I 100 99.58 AV-II-M1 100 95.24 AV-II-M2 78.57 80 AV-III 76.12 99.23 Displaying P waves in Bird View In the Cardiospy software using the Bird View option, the presence or absence of P waves or changes in morphology can be easily inspected visually:
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.