In the previous article, the mechanism of congenital heart disease combined with pulmonary arterial hypertension (hereafter referred to as PAH) was briefly described, as well as the relationship between surgical correction of congenital heart disease and the developmental status of PAH. In this chapter, we will discuss the specific clinical diagnostic process and the development of the treatment plan. 1. My baby is now 9 months old and an ultrasound revealed a ventricular septal defect. The doctor said that the pulmonary hypertension is now severe, is there still a chance for surgery? This question was covered in the first article. If a ventricular septal defect (or other left-to-right shunt heart disease) is large (what we call a “non-restrictive” ventricular defect), a large shunt of blood from the body to the pulmonary circulation can lead to a significant increase in pulmonary artery pressure. However, in the early postnatal period, the elevated pulmonary artery pressure is caused by pulmonary artery congestion. After correction of the ventricular defect, the body-pulmonary shunt is terminated, the volume of blood in the pulmonary artery is reduced, and the pulmonary artery pressure will naturally decrease; only when the pulmonary vessels gradually thicken, contracture, and form organic pulmonary hypertension, will the opportunity for surgery be lost. Therefore, even if the ultrasound suggests high pulmonary artery pressure, patients with ventricular deficiency in infancy can usually receive surgical treatment. Conversely, the finding of significantly elevated pulmonary artery pressure often implies a larger caliber of ventricular defect and a greater impact on the child. Such children tend to be more prone to pneumonia and heart failure, and the development of pulmonary hypertension is more rapid. Therefore, surgery should also be performed early. The first mouse and hesitation may lead to a big mistake. 2. The patient is 10 years old and has just discovered a ventricular septal defect. The doctor said that the pulmonary artery pressure is now too high for surgery, so how do we know if there is a chance for surgery? As the patient grows older, the pulmonary hypertension caused by precordial disease will become more and more severe, and the child/patient will show the corresponding clinical manifestations. The degree of development of pulmonary hypertension can be initially determined by taking a medical history and a brief examination. Our main concerns are: ① Cyanosis: As hypoxia increases and the direction of blood shunting evolves, patients with precordial disease combined with PAH often present with cyanosis of the lips and nail bed, which we call cyanosis. The presence of cyanosis often means that PAH has become quite severe. If cyanosis is present only during exercise, further evaluation is possible; if cyanosis is evident in the quiet state, it mostly suggests that surgery is no longer possible. Pestle finger: In patients with severe hypoxia, the ends of the fingers/toes become increasingly enlarged and the nail bed bulges, this is called “pestle finger”. Pestle finger is often combined with cyanosis. If the patient already has significant pestle fingers, most of them cannot be operated on. Hemoptysis: This is a common symptom of advanced PAH. If hemoptysis has already occurred, the chances of surgery are slim. ④ Anorexia, wasting, abdominal distension, lower limb edema, etc.: As mentioned before, PAH progresses to a severe stage and causes right heart insufficiency (right heart failure). And these symptoms or signs are common manifestations of right heart failure. Patients who have already developed right heart failure are usually inoperable. It is important to note that these signs can also be seen in other types of precardiac disease or in other systems of disease, with different clinical implications. In particular, we will discuss here the case of “left-to-right shunt” preconditioning combined with PAH, which should not be confused. 3. What tests are available to determine the degree of development of pulmonary hypertension? In addition to clinical manifestations, there are a number of tests that are important in assessing pulmonary hypertension. These include: ① Transcutaneous oxygen saturation (SpO2) or arterial oxygen saturation (SaO2): As PAH progresses, pulmonary blood decreases significantly and so does the oxygen intake. Oximetry provides a visual representation of the amount of oxygen in the blood and is easy to measure. Generally speaking, patients with oxygen saturation over 95% are more likely to undergo corrective surgery for preexisting heart disease; if it is below 90% or even below 85%, the chance of surgery is slim. ② Chest X-ray: Chest X-ray is essential to assess the degree of development of PAH. By studying the chest radiographs, the degree of development of pulmonary artery lesions can be roughly grasped and the feasibility and clinical outcome of surgery can be predicted. Although there is a lack of quantitative objective criteria, experienced physicians pay more attention to chest radiographs than even right heart catheterization. (iii) ECG: Patients with PAH will present with typical ECG manifestations (e.g., pulmonary P waves). More importantly, the ECG reflects left and right ventricular hypertrophy. If the patient has predominantly left ventricular hypertrophy, it often suggests that the procedure can be performed safely, whereas if the patient has biventricular hypertrophy or even predominantly right ventricular hypertrophy, the safety of the procedure will be greatly compromised. Echocardiography: Echocardiography is the most important test to confirm the diagnosis of precordial disease and pulmonary hypertension, and is the basic basis for clinical diagnosis. If the echocardiogram indicates that the type of precordial disease originally “left-to-right shunt” evolves into “bidirectional shunt” or even “right-to-left shunt”, it means that the patient has developed severe pulmonary hypertension. It is important to note, however, that even if the shunt is not a right-to-left shunt, the patient may have a severe pulmonary hypertension. It is important to note, however, that even if the direction of the shunt has changed, this does not mean that the patient is completely lost to surgery (although this is true in most patients), and relying on ultrasound alone may deprive the patient of the last chance for correction. ⑤ Right heart catheterization and rapid pulmonary artery dilation test: Right heart catheterization is by far the most objective, effective, and authoritative means of assessing pulmonary hypertension. With right heart catheterization, the patient’s pulmonary artery pressure, body/pulmonary circulation blood volume and pulmonary artery resistance can be accurately measured. Of these, pulmonary artery resistance is the key data to determine whether the patient can be operated (although other indices are also important). The so-called rapid pulmonary artery dilation test is done after adequate oxygenation or inhalation of pulmonary artery dilation drugs, followed by completion of a right heart catheterization. The aim is to exclude interference from functional factors such as pulmonary artery spasm and to more accurately measure the extent of disease development in the pulmonary vasculature itself. Therefore, we recommend that all patients with PAH undergo standardized right heart catheterization and rapid pulmonary artery dilation test; for patients with PAH in combination with precordial disease, even if surgery is not possible, they should undergo this test to grasp the current progression of pulmonary hypertension as a guideline for drug treatment. 4. The patient has already had a right heart catheterization and the pulmonary artery resistance is 8 Wood units, what does this mean? Is it definitely not possible to do surgery? Wood Unit (WU) is a standard unit of measurement of pulmonary artery resistance. Pulmonary artery resistance in a normal person is less than 3 Wood Units. in patients with PAH, pulmonary artery resistance may be significantly elevated. In some patients, pulmonary artery resistance decreases significantly, even to the normal range, after undergoing a rapid pulmonary artery dilation test; this indicates that functional factors account for a high proportion of the composition of their pulmonary hypertension, and such patients, often, can undergo corrective surgery for precordial disease. Unfortunately, there is no definite conclusion as to how much the pulmonary artery resistance is elevated and the surgery is not feasible. Some foreign scholars believe that if the pulmonary artery resistance is significantly elevated, surgery is no longer possible; the criteria we currently use are: patients with normal pulmonary resistance can definitely be operated; if the pulmonary resistance is elevated, but still below 7-8 Wood Units, surgery can be performed safely; if it is further elevated, but still below 10-11 Wood Units, the risk of surgery will continue to rise. If the pulmonary artery resistance increases again, the development of PAH can no longer be overcome by corrective surgery, and the surgery will be meaningless. It is important to note that modern medicine is still developing and deepening its understanding of PAH. Although right heart catheterization is of great importance in confirming the diagnosis of PAH, in clinical practice, we cannot make the final treatment plan based on this test alone. Only by taking into account the clinical manifestations and the results of multiple ancillary tests and making prudent treatment decisions can we truly reduce the risk of surgery and improve the long-term prognosis of patients. In addition, although some primary units already have the ability to perform right heart catheterization, the operation is not standardized and the basic principles of right heart catheterization are not well understood, which may also lead to wrong conclusions. For example, we emphasize that right heart catheterization should be able to measure small pulmonary artery resistance, and many units incorrectly equate whole pulmonary vascular resistance with small pulmonary artery resistance, which may lead to high final calculated values, resulting in incorrect clinical decisions by physicians.