Aortic aneurysm (aortic aneurysm) refers to an abnormal local or diffuse expansion of the aortic wall that causes symptoms by compressing the surrounding organs, with aneurysmal rupture as its main risk. According to the structure aortic aneurysm can be divided into: 1. true aortic aneurysm: the sac of the aneurysm consists of one or more layers of the arterial wall; 2. pseudo-aortic aneurysm: due to trauma, infection, etc., blood spills out of the artery into the tissues surrounding the artery, and the blood clot and its mechanized matter and fibrous tissue together with the arterial wall constitute the wall of the aneurysm; 3. intermural aneurysm (aortic coarctation). After tearing of the intima or middle layer of the artery, blood flow impact gradually separates the middle layer into a sandwich, accumulating blood and bulging in the separated lumen, which may also form a double-lumen structure with the arterial lumen. Clinically, many types of conditions can cause aortic injury and the formation of aortic aneurysms, including true, pseudo, and intermural aortic aneurysm forms. Of these, penetrating injuries cause aneurysms directly in the damaged aorta and can occur at any site, and the location of aortic aneurysm rupture is easily determined. In indirect injuries, the location of aortic aneurysm rupture is not easy to determine because there is often no wound on the body surface. For example, when chest compressions are performed, when the chest is hit in front in a car accident, when an athlete falls from a bar, and during pregnancy. The mechanism of these indirect injury factors is similar to that of “pumpkin picking”. The heart is like a hanging “pumpkin”, the aorta connected to the heart is like the “vine” of the pumpkin, and the root of the aorta is equivalent to the “tip” of the pumpkin. If you gently push a hanging “pumpkin”, the “pumpkin” will swing in a back and forth direction like a pendulum, and at this time, the part of the pumpkin’s “tip” is the easiest part to break. This is the easiest part to break, because this part is a spherical object (pumpkin), and the connection of the tube-shaped object (vine) (tip), is the weak link in mechanics. As in CPR when doing chest compressions, the heart will also be like a “pumpkin”, appearing to swing in a forward and backward direction, when the aortic root is most likely to be damaged, and the aortic aneurysm rupture is mostly located in the aortic root. Since part of the aortic root is located in the pericardium, blood will enter the pericardial cavity when the aortic root is injured, so blood accumulation in the pericardium and pericardial tamponade can be seen during cardiopulmonary resuscitation, which is one of the reasons why cardiac resuscitation is clinically ineffective. In addition, if an aortic wall interstitial aneurysm is formed, the location of its rupture into the lumen depends largely on the location of the primary tear within the lumen. Pericardial hemorrhage is the main cause of death from aortic wall interstitial aneurysm, in which 70% of the ascending aorta ruptures toward the pericardium; the aortic arch ruptures toward the pericardium then drops to 35%; the thoracic descending aorta is 12.3%; and only 7% of the primary tears are in the abdominal aorta. In addition to pericardial hemorrhage, thoracic segment rupture bleeding is most likely to occur in the left side, the ratio of its right side is about 5:1. If you push a hanging “pumpkin”, the spherical object (pumpkin) will move backward quickly, while the tubular object (vine) is still at rest, the most likely to break The easiest part to break is also the connection between the two (the tip). Therefore, when the chest is hit in front, the heart, like a “pumpkin”, will have a rapid backward motion, while the aorta is still at rest, and the root of the aorta is most likely to be damaged at this time. In the spring of 1987, I was studying for my master’s degree and was working on the front line of the clinic when I met a middle-aged male patient. He was diagnosed as “lung cancer” (CT was not popular at that time) and underwent radiotherapy. After several cycles of treatment, no significant changes were found in the mediastinal masses, so he came to our hospital. The patient recalled that a few days before the onset of the disease, when he was traveling on a train, a passenger in front of him hit his front chest with his elbow because it was very crowded, and he felt a tearing pain in his chest at that time. Based on the patient’s medical history and examination, an aortic pseudoaneurysm was suspected. An angiogram was then performed, which confirmed that the aortic rupture was located at the root of the aorta and a pseudoaneurysm was formed. The patient later died of suspected aneurysm rupture after sudden cardiac and respiratory arrest several hours before the proposed surgical treatment. The rupture may also be related to radiation therapy damaging the envelope of the pseudoaneurysm. Third, during deceleration exercise During deceleration exercise, such as falling from a bar and landing on the back; when a car accident knocks the patient off the ground and lands on the back of the body; the location of aortic injury rupture is mostly located in the aortic isthmus, that is, at the connection between the distal segment of the aortic arch and the thoracic descending aorta, also known as the aortic isthmus, adjacent to the arterial duct or arterial ligament area. In addition, the majority (more than 95%) of lesions in the constricted segment of the aorta are also located in this region. The arterial duct and arterial ligament The arterial duct is a duct located between the base of the left pulmonary artery and the beginning of the descending aorta. During fetal life, the lungs are atrophied and the resistance of the pulmonary vasculature is high, so most of the blood draining from the right ventricle to the pulmonary artery enters the descending aorta through the arterial duct. After birth, the lungs expand and contract with respiration, and the resistance of the pulmonary circulation then decreases, so that the blood discharged from the right ventricle enters the lungs on both sides for gas exchange. When the pulmonary arterial pressure is equal to that of the aorta, the arterial duct is functionally closed. The ducts gradually close histologically to form the arterial ligament due to physiologic abandonment, changes in the angular position of the ducts as the lungs expand, and certain unexplained factors. Statistically, 88% of infants have their ducts closed within 2 months of birth and 98% within 8 months. If the duct is still open at 1 week of age, it has less chance of closing on its own later on, i.e., forming a ductal nonclosure (syndrome). In summary, the fibrous connective tissue cord that runs from the bifurcation of the pulmonary artery trunk slightly to the left to the lower edge of the aortic arch, the arterial ligament, is a remnant of the fetal atresia of the ductus arteriosus after birth. It is very much like a “rope welded to the lateral wall of the aorta”. 2, “rebound” injury In the deceleration movement, such as the patient fell from the bar, the back landed; the heart first moved in the direction of the back, when the back landed, the heart movement decelerated, and then “rebounded” back to the chest direction, and led the arterial ligament forward Movement, at this time, “a rope welded to the lateral wall of the aorta”, will be hard in the aortic isthmus left a “breach”. This is one of the mechanisms of aortic injury during deceleration exercise. The mechanism of aortic injury during pregnancy is very similar to the action of “pumpkin twisting”, which can be examined from the combination of the philosophical view of space and time. The discursive materialist view of space and time is that there are three dimensions of space: up and down, left and right, and front and back; and one dimension of time: past, present, and future. （As the duration of pregnancy increases and the fetus grows in the abdomen, the lifting force on the patient’s diaphragm and heart will gradually increase. 2.Hormone level With the prolongation of pregnancy, the level of estrogen and progesterone in pregnant women changes, which can cause cystic changes in the middle layer of the aorta and is one of the important factors that predispose to aortic wall interstitial aneurysm. Studies have shown that about half of the aortic wall aneurysms in women under 40 years of age occur during pregnancy, and most occur within the second trimester or early in the puerperium. It has been shown that estrogen significantly reduces the activity of glycogenolysis in the arterial wall, causing damage to the arterial wall. This may be related to estrogen-induced atrophy of the arterial smooth muscle, leading to an inflammatory response in the vessels involved, resulting in thickening of the fibroblastic tissue of the intima, thickening or thinning of the intima, fibrous degeneration, and breakage, overlapping or loss of fibrous tissue and elastic fibers. It has also been suggested that estrogen induces a decrease in the activity of certain enzymes in the arterial mesothelium as a mechanism for the inflammatory changes in the arterial wall. However, some scholars have denied the effect of estrogen on the vessel wall through experiments and believe that it is most likely caused by hemodynamic changes during pregnancy, but some scholars still insist that it is related to changes in connective tissue during pregnancy, and this issue is still inconclusive. (ii) Spatial dimension 1. Up and down direction During pregnancy, the fetus enlarges in the pregnant woman’s abdomen, and the patient’s diaphragm is elevated, pushing the heart upward. However, above the heart is the aortic arch, and there are three arterial great vessels (cephalic brachial artery, left common carotid artery, and left subclavian artery) supporting it above the aortic arch, so it is difficult to move the heart upward. 2. Anterior-posterior direction The front of the heart is the sternum, and the back is against the spine. There is not much space in the anterior-posterior direction of the heart, which can relieve the pushing force of the diaphragm elevation on the heart when the patient is pregnant. Theoretically, the pressure around the chest on both sides of the heart is in a dynamic balance. Under the influence of factors such as movement and position change, the pressure between the left and right side of the heart and various parts of the heart will become unbalanced, and the heart will move to the side or direction with lower pressure, thus producing a force that makes the heart rotate, similar to “When picking a pumpkin, the action of “twisting the pumpkin” is similar to that of the aorta, so at this time the aortic injury is mainly at the root. In short, Xunzi said in “Ontario”, “good scholars do their best, good practitioners investigate their difficulties. The doctor, from the reasoning of “picking pumpkin”, leads to some methods of determining the location of aortic aneurysm rupture, which is an example of “exhausting its reasoning”, and is also a reflection of clinical divergent thinking.