After the blood flow of the main blood vessel (artery or vein) in a certain part of the body is blocked, the blood vessels of the original anastomotic branch of the part expand and form bypasses, so that the blood passes through these bypasses in a roundabout way and restores the circulation, this circulatory pathway is called “collateral circulation”, also called “compensatory circulation This circulatory pathway is called “collateral circulation”, also known as “compensatory circulation”. Inadequate development of the collateral circulation means that these bypasses are not sufficiently developed, which still affects the circulation and can cause various cardiovascular diseases. What are the tests for underdeveloped collateral circulation? 1, chest fluoroscopy Fluoroscopy is a direct examination in which the patient is placed between the X-ray tube and the fluoroscope. It can do comprehensive dynamic direct observation, such as heartbeat, transverse septal activity, gastrointestinal motility, joint activity, etc. It can also be used in X-ray imaging for positioning observation, gastrointestinal imaging, and instructions for diagnostic and treatment operations such as cardiac catheterization, fracture repositioning, foreign body removal, etc. The most commonly used part of X-ray fluoroscopy is the chest to examine the lungs, pleura, mediastinum, heart, and large blood vessel lesions. 2, magnetic resonance imaging (MRI) MRI, also known as magnetic resonance imaging, is the use of the principle of nuclear magnetic resonance, through the application of gradient magnetic field detection of the emitted electromagnetic waves, according to which the internal structure of the object can be drawn into the image. 3.Cardiovascular angiography Cardiovascular angiography is the rapid injection of contrast agent into the heart or blood vessels through the cardiac catheter, so that the heart and blood vessel cavities are visualized under X-ray irradiation, and at the same time, there are methods such as rapid film, television photography or magnetic tape recording to film the visualization process of the heart and blood vessel cavities. It is a valuable method to diagnose the heart and blood vessels. It is a valuable method to diagnose cardiovascular disease. Although the density resolution of plain CT is much higher than that of plain X-ray, there are still some lesions that show iso-density changes on plain CT scan, or lesions that have been shown on plain CT and it is not clear whether the blood supply is rich or not, it is necessary to enhance the lesions with the help of contrast. lesion. 5.Doppler echocardiography There are many red blood cells within the blood, which can reflect and scatter ultrasound and can be considered as a tiny source of sound. The probe is placed in the intercostal space without moving and emits ultrasound. When the red blood cells flow in the heart or large blood vessels, the sound frequency scattered by the red blood cells changes. As the red blood cells move toward the probe, the reflected sound frequency increases, and vice versa, decreases. This difference in sound frequency between the red blood cells and the probe in relative motion is called the Doppler shift. It shows the speed and direction of blood flow and the nature of the blood flow. Doppler echocardiography is divided into pulsed Doppler echocardiography, continuous wave Doppler echocardiography, and color Doppler echocardiography. The most commonly used is pulsed Doppler echocardiography, which provides a real-time Doppler spectrogram of blood flow at any point in the heart with two-dimensional image monitoring and positioning.