In clinical practice, we often encounter patients complaining, “Why do I have to do ultrasound and angiography after having an ECG? If the heart is a 4-bedroom house, ultrasound can see how big the room is, whether the walls are solid or not, and whether the door is tight or not; ECG can see whether the circuit is open or not, and whether there is any short circuit and leakage; imaging is to see whether the water pipe is blocked or not, whether there is rust or not, and whether it needs to be unblocked, which can only be understood by imaging. The three types of tests are used for different purposes to complement each other and cannot be replaced. What heart disease is ultrasound used to check? The heart is a 4-bedroom house structure, and the ultrasound looks at how big the room is, how strong the walls are, and how tight the doors are. Ultrasound is also known as echocardiography, which is equivalent to a doctor’s “fluoroscopic eye” and can see the structure and size of the heart without opening the chest. It is mainly used to diagnose valvular heart disease, congenital heart disease, various primary and secondary cardiomyopathies, and also has some reference value for the diagnosis of coronary heart disease. What heart diseases can be diagnosed by ECG? The pumping function of the heart is achieved through coordinated contraction and diastole of the heart muscle, which requires circuits (conduction tissue of the heart) to transmit commands. The ECG is mainly used to see if the circuits in the house are open or closed, and if there are any leaks. In other medical terms, it is mainly used to diagnose arrhythmias, including premature beats, tachycardia, bradycardia, etc. An electrocardiogram is the best non-invasive way to diagnose arrhythmias. Usually only a routine ECG is needed, but if a routine ECG does not reveal an arrhythmia or if the severity of the arrhythmia needs to be assessed a 24-hour ambulatory ECG (also known as a Holter) is required. An ECG can confirm the diagnosis of myocardial infarction with ST-segment elevation, and patients with chest pain should first have an ECG to rule out the possibility of myocardial infarction. However, the diagnostic value of myocardial ischemia is not high, but only suggestive value. One cannot diagnose myocardial ischemia simply by ST-T changes and label it as coronary heart disease. In addition, electrocardiogram also has some suggestive value for myocardial hypertrophy, heart enlargement, low potassium and low calcium, but it cannot confirm the diagnosis. What kind of heart disease is coronary angiography used to diagnose? Coronary arteries are equivalent to the water pipes in a house. To see if the pipes are clogged, rusted or need to be unclogged, coronary angiography is needed to diagnose coronary heart disease. There are two types of coronary angiography, one is invasive coronary angiography done in the catheterization room, which is the “gold standard” for diagnosing coronary heart disease. It requires hospitalization and is mainly suitable for patients with typical angina symptoms, or for patients with non-invasive tests suggesting coronary artery disease. The other is coronary CTA, which is a non-invasive test that does not require hospitalization. However, the accuracy is poor, around 80%, and is mainly indicated for patients with atypical symptoms of chest pain. If there are no symptoms related to angina pectoris it is not recommended to use coronary CTA for the examination of healthy people. A reasonable diet, good exercise habits, non-smoking, maintaining a good state of mind, and good weight control can make a house stronger, slow down the aging of electrical circuits, keep the contents of the room from being overly bloated, and keep the plumbing open.