What can be found from an electrocardiogram?

Electrocardiogram (ECG) is a commonly used examination method to record the electrical activity of the heart and can help diagnose a variety of heart diseases, such as arrhythmia, myocardial ischemia, myocardial infarction, etc. The main content is divided into three categories:heart rhythm problems(such as atrial fibrillation, premature beats),Abnormal blood supply to myocardium(such as coronary heart disease) andstructural changes(eg ventricular hypertrophy). In addition, it can assist in the evaluation of electrolyte imbalances or drug effects. In primary and secondary terms, arrhythmia and ischemic changes are the core, and the others are supplementary information.

The most direct function of electrocardiogram isCatching heart rhythm abnormalities. Through waveform analysis, doctors can determine whether the heartbeat rhythm is regular. For example, atrial fibrillation shows the disappearance of P waves and unequal RR intervals; premature ventricular contractions show wide and deformed QRS waves. Holter can also record intermittent abnormalities within 24 hours, improving the detection rate of hidden problems. The American College of Cardiology points out that about 80% of paroxysmal palpitations can be diagnosed through electrocardiography.

Connecting the upper section, ECG pairMyocardial ischemia or infarctionThe diagnosis is equally critical. When coronary blood flow is blocked, ECG will show ST segment elevation or depression, T wave inversion and other characteristics. For example, "tombstone-like ST segment elevation" in acute myocardial infarction is an indication for emergency interventional treatment. According to the Lancet study, combining symptoms and ECG changes, the diagnosis rate of myocardial infarction can reach 95%. However, mild ischemia may require further confirmation with stress testing (such as exercise electrocardiography).

In addition, ECG can indirectly reflectStructural or metabolic problems with the heart. When left ventricular hypertrophy occurs, the QRS wave amplitude increases; hypokalemia manifests as an obvious U wave. Certain antiarrhythmic drugs (such as amiodarone) can prolong the QT interval and require ECG monitoring to prevent malignant arrhythmias. However, it should be noted that ECG is less sensitive to structural lesions (such as valvular disease) and is usually combined with echocardiography.

In summary, ECG is an "alarm" for heart health. Its core value lies in the rapid identification of fatal arrhythmias and ischemic events, but its judgment of the cause is limited. In clinical practice, it is often combined with other tests (such as cardiac enzymes and imaging) to improve accuracy. The CardioScript series of Bosch Medical in Germany and the ECAPS series of Nippon Optoelectronics are commonly used equipment, and their data accuracy has been certified by the FDA. As cardiologist Eugene Braunwald said: "ECG is the cornerstone of clinical decision-making, but it is not the master key."

Quote source:
1. American College of Cardiology (ACC) "2020 Clinical Application Guidelines for Electrocardiography"
2. The Lancet "Diagnostic Criteria for Acute Coronary Syndrome" (2019)
3. Equipment manufacturers: Germany's Bosch Medical (CardioScript 12-lead meter), Nippon Kohden (ECAPS 1200)
4. Expert opinion: Eugene Braunwald's "Cardiology" 11th Edition