| 摘要 |
<p>The invention presents a medical device system (10) and method for determining the degree of heart failure of a patient, utilizing information representative of dynamic variations in patient QT, or segments of QT, over time. The dynamic variations in QT that are measured relate to characteristics of the variation of QT with rate when rate is increasing and when it is decreasing. The dynamic variations include QT dynamic range, QT hysteresis, and QT directrix, each providing important information relating to the patient's variation of QT with heart rate, or QT(RR). QT and dynamic variations of QT can be measured in both left and right ventricles, and taken over the patient's normal rate range. The dynamic data is measured and stored periodically and compared with historical data to determine progression toward heart failure. In another embodiment, the QRST signals are divided into segments, namely QRS width; ST segment; and T wave width, and variations of these segments are analyzed to provide additional information indicative of the patient's heart condition. Preferably the system utilizes a microprocessor (64) programmed to carry out an algorithm that weighs detected variations in QT, QT segments and/or QT dynamic parameters with time to track cardiac changes.</p> |
