Deputy Director, Xie Kai-sheng (right), emphasized that in adults over 18, if brain infections are not due to serious head injuries, they are often related to congenital structural heart diseases, regardless of previous obvious symptoms. Dr. Dai Yi-xin (left), upon examining A-Cheng's heart, discovered an atrial septal defect. Coupled with the right atrium's deoxygenated blood backflow into the left atrium, bacteria massively invaded the brain, causing a severe infection, brain abscess, and subsequent hydrocephalus. The pediatric cardiology team at the children's hospital then performed a 'transcatheter atrial septal occlusion procedure' to prevent recurrence of the brain abscess. Post-surgery, A-Cheng has been recovering well and is currently undergoing continuous rehabilitation.

      Ah Cheng, a 24-year-old young man with a congenital heart defect, was discovered unconscious one morning by his roommate. He was rushed to the emergency room at China Medical University Hospital, where he underwent a magnetic resonance imaging (MRI) scan of his brain. He was diagnosed with 'brain abscesses complicated by obstructive hydrocephalus. Neurosurgeons immediately performed surgery to remove the abscesses in his brain. After the operation, Ah Cheng regained consciousness and it was discovered that he had been experiencing symptoms of headaches, dizziness, and limb weakness for several months, and even had feverish symptoms of infection.
 

The MRI image showcases the location of a brain abscess (shown in white) in the left hemisphere of the patient, A-Cheng. Hydrocephalus can lead to impairments in the contralateral motor function. Since the left hemisphere predominantly controls language, verbal comprehension abilities could also be affected.

​      The medical expert team at China Medical University Hospital assessed that the abscess that developed in the young man's brain may be related to his congenital heart disease. After further diagnostic examination by Dr. I-Hsin Tai from the Pediatric Cardiology Department of China Medical University Children's Hospital, Ah Cheng was found to have an 'atrial septal defect with right-to-left shuntingdetected by a 'bubble test' (Agitated Saline Echocardiography) and cardiac catheterization. This was determined to be the cause of his chronic hypoxia, as the deoxygenated blood in the right atrium flowed back into the left atrium, allowing bacteria to invade the brain in large numbers, causing severe abscess infection and consequent hydrocephalus. Fortunately, Ah Cheng was promptly rescued. The cardiac specialist team at the Children's Hospital then closed the congenital defect in Ah Cheng's heart through a 'transcatheter atrial septal closure procedure', preventing the recurrence of brain abscesses. After a successful recovery, Ah Cheng is currently undergoing continuous rehabilitation.
 

 The bubble test ultrasound depicts bubbles (shown as white within the red circle) rushing from the atrial septal defect (a 1.5 cm hole) in A-Cheng's right atrium to his left atrium.

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      Professor Kai-Sheng Hsieh , Vice Superintendent of the Children's Hospital at China Medical University and Director of the Structural and Congenital Heart Disease and Ultrasound Center, further analyzed that the age group most susceptible to brain abscesses in China is usually men over 60 years old. The sequelae caused by brain abscesses include recurrent obstructive hydrocephalus, neurological deficits, and seizures. In severe cases, it can even lead to death. Therefore, the public should not take it lightly. However, according to Vice Superintendent Hsieh, it is extremely rare for a patient in their twenties, like Ah Cheng, to develop a brain abscess. Clinically, this is mostly related to congenital structural heart disease.
 

Long-term hypoxia in patient A-Cheng has resulted in clubbing, which is manifested by swollen fingertips and nails that arch from the base to the tip. This results in an increased angle between the nail bed and the distal interphalangeal joint, possibly exceeding 180 degrees (shown on the left). Normally, the angle between the nail bed and the first finger joint is typically between 150 and 160 degrees, and the angle between the nail bed and joint is less than 160 degrees (shown on the right).

      Dr. I-Hsin Tai ,the Pediatric Cardiology Department of China Medical University Children's Hospital, points out that approximately 3-4 in every 1000 newborns in Taiwan suffer from 'atrial septal defect', but the majority are accompanied by 'left-to-right shunting', which would not lead to brain abscesses. For adults, those with a defect diameter of less than two centimeters generally do not present noticeable symptoms. If the diameter of the defect exceeds two centimeters, however, due to excessive pulmonary blood flow, patients may experience shortness of breath, fatigue, and recurrent respiratory infections.
 

 Dr. Dai Yi-xin, a pediatric cardiologist at China Medical University Children's Hospital, pointed out that in Taiwan, about 3 to 4 out of every 1,000 newborns suffer from 'atrial septal defect', most of which involve 'left-to-right shunting' and would not lead to brain abscesses. In adults, if the diameter of the defect is less than two centimeters, there are usually no noticeable symptoms. However, if the defect is larger than two centimeters, due to excessive blood flow to the lungs, patients may experience shortness of breath, fatigue, and recurring respiratory infections. Dr. Dai stressed that when the ratio of pulmonary blood flow to systemic blood flow exceeds 1.5 times during cardiac catheterization examination, it should be considered for closure through minimally invasive catheter surgery.

​      Dr. I-Hsin Tai emphasizes that when a heart catheterization shows that the ratio of pulmonary to systemic blood flow is greater than 1.5, a minimally invasive catheter surgery should be considered for closure. However, in exceptional cases like Ah Cheng's, where other structural heart anomalies lead to 'right-to-left shunting'—any purulent infections anywhere in the body can bypass the venous-pulmonary system and directly enter the arterial system from the 'hole' of the atrial septal defect, resulting in a bacterial infection turning into an abscess. In such urgent situations, it is recommended that the atrial septal defect should be closed as soon as possible, regardless of the size of the hole, in order to prevent further brain abscesses. This treatment has a short recovery period and is covered by health insurance.

Dr. Dai Yi-xin from China Medical University Children's Hospital explained that closing the hole in the atrial septum requires careful operation. The illustrated image depicts the placement of a nickel-titanium alloy septal occluder. The left disk is deployed in the left atrium and then clasps the septal defect; subsequently, the right disk is released in the right atrium. The defect is closed by clamping it with the left and right disks.

​      Dr. I-Hsin Tai explains that in a normal person, the pressure in the left atrium is slightly higher than that in the right atrium. However, in cases like Ah Cheng's where heart disease is compounded by other structural heart abnormalities, this leads to an accumulation of blood flow in the right atrium, causing its pressure to exceed that of the left atrium. The deoxygenated blood in the right atrium then flows back into the left atrium, and mixes with oxygenated blood, leading to chronic hypoxia. This is known as 'right-to-left shunting'. When the pressure difference between the left and right atria approaches zero, a Doppler echocardiogram is unable to detect this difference in blood flow pressure, requiring the additional use of an 'Agitated Saline Echocardiography' (bubble test).

Professor Xie Kai-sheng (right), the deputy director of the 'Structural and Congenital Heart Disease and Ultrasound Center' at China Medical University Children's Hospital, along with Dr. Dai Yi-xin (left), pointed out that brain abscesses are predominantly seen in men aged sixty and above within the country. The complications arising from brain abscesses include recurrent obstructive hydrocephalus, loss of neurological functions, epileptic seizures, and in severe cases, even death; these potential risks must not be underestimated by the public. However, Professor Xie stated that the incidence of a brain abscess in a patient like A-Cheng, who is only in his early twenties, is extremely rare. In clinical settings, such cases are usually associated with congenital structural heart diseases.

​      Dr.Tai states that 'atrial septal defects combined with right-to-left shunting' not only lead to brain abscesses but also carry another risk associated with the occurrence of 'cryptogenic stroke in young people.' According to the Taiwan Heart Association, cryptogenic strokes are mostly related to patent foramen ovale. However, 'atrial septal defects combined with right-to-left shunting' are more prone to allow small blood clots to enter the left systemic circulation than patent foramen ovale, potentially leading to the blockage of cerebral vessels and resulting in ischemic strokes.

​      Vice Superintendent Hsieh emphasizes that for adult patients over 18 years old, if brain infection is not caused by severe head trauma, regardless of whether there are evident symptoms of past illnesses, the occurrence of brain infection is mostly related to congenital structural heart diseases. If clinically observed signs such as 'clubbing' (a fingernail bed angle greater than 180 degrees), erythrocytosis (normal male levels are 12-14g/dL), and insufficient arterial blood gas saturation (normal levels are 95-100%) are present, these are caused by long-term hypoxia, and it would be appropriate to seek pediatric card the symptoms mentioned above, they should not delay biology for differential diagnosis of atrial septal defects. Especially for young adults with congenital heart diseases, regular follow-up visits are needed to prevent unfortunate incidents from happening. Hsieh mentions that both 'minimally invasive closure surgery via heart catheterization' and 'agitated saline echocardiography (bubble test)' are covered by health insurance. If the public experiences the relevant symptoms mentioned above, they should not delay in seeking medical help and should consult a doctor's professional opinion as soon as possible.