New uses of dynamic electrocardiograph

DCG is not only used in the detection of arrhythmia qualitatively and quantitatively, but also helps to guide the clinical application of antiarrhythmic drugs; it is widely used in detecting myocardial ischemia; screening for possible cardiac events after myocardial infarction in high-risk patients; evaluating the efficacy of drugs and evaluating the function of pacemaker and cardiac automatic defibrillator (AICD), which provides a reliable basis for clinical diagnosis and treatment. Some dynamic electrocardiogram software also adds late potential and pacemaker analysis functions. Analysis of late potentials is of great clinical value. Continuous studies, such as comparative analysis of arrhythmic time and other time, show that positive late potentials are common in spontaneous or evoked ventricular tachycardia. Ltd.

(1) Sinus heart rate turbulence (HRT). Normal people, when the vegetative nerve function is normal, sinus rhythm usually accelerates first and then slows down after the first ventricular premature. This phenomenon is called sinus heart rate turbulence. The phenomenon of heart rate turbulence weakened or disappeared after ventricular premature beats in patients at high risk of sudden death after myocardial infarction and severe heart failure. According to Professor Guo Jihong, Peking University People's Hospital, there are some limitations in the methods and indicators used to predict sudden death, such as left ventricular ejection fraction, ventricular late potential, heart rate variability, electrophysiological examination, etc. However, the detection of ventricular premature and postventricular sinus heart rate turbulence is a new method. The patient recorded 24 hours dynamic electrocardiogram. By measuring two values of TO (initial shock) and TS (slope of shock) after premature ventricular beats, the computer could detect whether there was acceleration or slowdown after premature ventricular beats, thus predicting the risk of sudden death. Studies have shown that TO and TS are two independent predictors of mortality risk. Both of them are positive, which increases the risk of sudden death by four times.

(2) Microvolt T-wave alternation: Dynamic electrocardiogram software equipped with microvolt T-wave alternation detection function for screening high-risk sudden death patients. At present, microvolt T-wave alternating detection is mainly used in patients with known or suspected ventricular arrhythmia and sudden death risk.  Several studies have shown that microvolt T-wave alternation is as valuable as invasive electrophysiological tests in predicting arrhythmic events. With the development of advanced signal processing and noise reduction technology such as multi-segment spectrum sensing electrodes, the original T-wave alternation used in exercise test can be measured in dynamic electrocardiogram, and has reached a high sensitivity and specificity. The risk of fatal arrhythmia and sudden death in patients with T-wave alternation positive is 11 times higher than that in negative patients. Therefore, microvolt T-wave alternation is an important index for predicting ventricular tachycardia and ventricular fibrillation. Compared with dominant T-wave alternation, it is more helpful for early detection of high-risk sudden death patients.

(3) Sleep apnea screening: At present, there are about 30-50 million people suffering from sleep apnea syndrome in China, and the prevalence rate is as high as 2%. If the patient had more than 20 sleep apneas per hour, his 5-year mortality rate would exceed 11% and the 8-year mortality rate would reach 37%. If early diagnosis and timely treatment can be made, symptoms can be eliminated, complications can be reduced and patients'quality of life can be improved. At present, the polysomnography can diagnose the disease effectively, but it is expensive and complicated to operate. It requires patients to stay in hospital for at least 7 hours. In addition, it is only carried out in large hospitals in China, which severely limits the detection of patients with sleep apnea syndrome. According to the latest report, great progress has been made in quantitative and qualitative preliminary screening of patients with sleep apnea syndrome by using ECG-derived breathing curve technology and heart rate variability. These techniques are a new function added on the basis of dynamic electrocardiogram (DCG). They do not need to add new equipment. They have little impact on patients'life and sleep, and do not increase the cost of examination. They are simple and cost-effective. Ltd.

(4) Evaluating the function of AV node: AV node is like a "black box" with many unknown areas. At the same time, it plays a very important role in heart conduction.  It is particularly important to accurately evaluate the function of atrioventricular node, and dynamic electrocardiogram has a prominent advantage in this respect. Because atrioventricular node conduction has the characteristics of decreasing conduction and time-varying with the increase of heart rate, and functional atrioventricular block has the characteristics of transient, intermittent and reversible, ordinary electrocardiogram can only record the electrocardiogram in a short resting state, so the evaluation of atrioventricular node function has obvious limitations. Dynamic electrocardiogram (DCG) can record continuously for 24 hours or even 72 hours. It has obvious advantages in evaluating AV node: detecting transient AV block; diagnosing frequency-dependent AV block and further differentiating functional or pathological AV block; diagnosing vagal AV block; evaluating the time-varying function of AV node; finding PR interval prolongation syndrome; differentiating 2:1 AV block from pathological AV block. Secondary type I or II (2:1 to 3:1 or 4:1) were observed; fast frequency dependent occult conduction of atrioventricular node was found; atrioventricular node function was evaluated during atrial fibrillation. Ltd.