How to detect stress ecg

by reallymake
July 19, 2021

stress ecg is a method for detecting early coronary heart disease. Although there is a certain percentage of false positives and false negatives compared with the results of coronary angiography, it has always been recognized as a method because it is simple, practical, non-invasive, and safe. An important clinical examination method for cardiovascular disease.

(1) Under the physiological and pathological basic physiological conditions of exercise test, in order to meet the increase in oxygen demand of muscle tissue during exercise, the heart rate will increase correspondingly, and the cardiac output will increase correspondingly, which will inevitably increase with the increase of the myocardial oxygen consumption basin and the increase of coronary blood flow. . When the coronary artery is diseased and narrowed to a certain degree, the patient may not have myocardial ischemia in the resting state, but when the exercise load increases with the increase in myocardial oxygen consumption, the coronary blood flow cannot increase correspondingly, which causes myocardial deficiency. Oxygen, abnormal changes may appear on the electrocardiogram. Myocardial oxygen consumption is related to heart rate, ventricle size, ventricular wall tension, rate of increase in internal pressure, and ventricular ejection time. In clinical practice, heart rate or the product of heart rate and systolic blood pressure is generally used to reflect myocardial oxygen consumption.

(2) Determination of exercise load The exercise load can be divided into two levels: extreme and sub-extreme. The maximum refers to the load at which the heart rate reaches its physiological limit. This kind of extreme exercise volume generally uses statistically obtained indicators of the estimated maximum heart rate of each age group. The rough calculation method of maximum heart rate is 220-age number; sub-maximal volume refers to the load at which the heart rate reaches 85% to 90% of maximum heart rate, and sub-maximal exercise tests are mostly used in clinical practice. For example, a 55-year-old subject has a maximum heart rate of 220-55=165 beats per minute. The submaximal exercise test requires that his heart rate should be 165 x 85% = 140 beats per minute.

(Three) stress ecg method

1. Mastcr two-stage ladder movement test was created by Master in the 1930s. According to age, gender, and weight, complete the specified number of second-level ladder climbing exercises within the specified time at an appropriate speed. Analyze the changes in the ECG before and after exercise to determine the results. Although this method is simple, easy to implement, economical and safe, it has a high false negative rate due to its small load and poor sensitivity. A few days ago, this method has been edited and eliminated.

2. The bicycle ergometer test allows the patient to exercise on a treadmill equipped with a power meter. The load is adjusted by speed and resistance, and the load level is gradually increased until the patient's heart rate reaches a sub-maximal level. . Before exercise, during exercise, and after exercise, ECG was recorded many times, and judgments were made by analyzing them one by one. The main advantage of this method is that according to the individual conditions of the subjects, they can reach their respective sub-maximal loads, which are in line with the principles and requirements of exercise tests, and the results are relatively reliable.

3. Treadmill test This is currently the most widely used exercise load test method. Let the patient walk on the active platform. According to the selected exercise plan, the instrument will automatically increase the platform speed and speed in order to adjust the load until the patient's heart rate reaches the sub-maximal level. The ECG changes before, during and after exercise are analyzed. critical result. Recent studies have shown that no matter what kind of exercise program, the best exercise time to reach the maximum oxygen consumption value is 8-12 minutes. Extending exercise time does not increase the diagnostic accuracy. It is emphasized that the choice of exercise program should be based on the specific conditions of different patients. set.