Echocardiography is an important method to assess the degree of vascular damage in KD complicated by HL. For children 5 years old and below, the chest wall is thin, echocardiography has good sound permeability, and can be repeated, non-radiation, non-invasive. The high-frequency ultrasound probe can clearly display the inner diameter, intima thickness and course of the coronary artery, and can quantitatively measure the degree of lesions. It has high sensitivity and specificity and is the first choice for early diagnosis and follow-up of coronary artery . In addition, echocardiography can clearly detect valvular regurgitation, pericardial effusion, segmental myocardial movement abnormalities, heart enlargement and other pathologies. It has become the first choice for children's cardiovascular system disease examination.
The incidence of HL in KD varies from country to country. The Pediatric Department of Weifang People's Hospital admitted 332 cases in children with KD in 5 years, of which 38 cases were complicated by HL, accounting for 11.45% of the total number of children with KD. The incidence of CAL is 10.84%, which is slightly higher than the latest Japanese report . In recent years, with the increase in the incidence of IKD, the incidence of CAL has also increased [7, 8, 22]. The occurrence of HL in KD is related to its pathophysiology. Systemic vasculitis is one of the characteristic lesions of KD, which is caused by excessive activation of the immune system. Continuous fever causes the release of inflammatory transmitters, leading to dysfunction of vascular endothelial cells, thereby enhancing the adhesion of leukocytes and participating in the formation of vasculitis [20, 23]. Such as Interleukin-6 (IL-6), etc. are significantly increased, especially in patients with IKD [24, 25]. The cardiovascular system in the acute stage of KD has obvious manifestations, including the pericardium, myocardium, endocardium, various valves and coronary arteries, which can cause arrhythmia, ventricular enlargement, valve regurgitation, and myocardial ischemia. KD most often invades the coronary arteries, causing them to dilate, stenosis, or harden. Especially IKD has a higher incidence of CAL than CKD [26–28]. Severe KD can lead to macrophage activation syndrome, causing multiple organ failure . Therefore, for clinically suspected KD patients, cardiac imaging examinations should be performed in time to confirm the diagnosis, so as not to miss the opportunity for diagnosis and treatment.
There are three interrelated vascular pathological processes in KD, acute self-limiting necrotizing arteritis (NA), subacute or chronic vasculitis (SA/C) and luminal myofibroblastic proliferation (LMP). NA is the neutrophil inflammation of the vascular endothelium synchronized with KD. It is a self-limiting process that starts and ends within 2 weeks of fever. SA/C vasculitis is asynchronous with the onset of KD. It is an inflammatory process dominated by small lymphocytes. It can begin within 2 weeks of onset and last for months to years, and is closely related to LMP lesions. SA/C vasculitis damages the blood vessel wall to varying degrees from the adventitia or surrounding tissues of the blood vessel, causing the blood vessel wall to form tumor-like expansion. LMP mainly causes stenosis of the lumen. Consistent with SA/C vasculitis, LMP can start within 2 weeks of onset and last for months to years .
The recovery of CAL is related to the degree of injury. The pathological basis of mild dilation is mainly NA, which is relatively easy to recover. The main pathological change of moderate to severe dilatation is SA/C, the disease has a slow recovery, and the recovery rate is low, which is consistent with our research. According to literature reports, the incidence of huge CAA (severe expansion) is 0.13–0.70% , and the possibility of recovery is very small . We have not found a huge CAA in our research. Since KD is a self-limiting disease, the coronary arteries with transient or mild dilation during the acute phase will usually return to normal within 3 months as the inflammation disappears in the late acute phase. With the application of gamma globulin and aspirin, myocarditis, pericarditis and other pathologies returned to normal in more than 6 weeks. Consistent with our research. Numerical changes of cardiac and coronary echocardiograms are closely related to clinical pathological changes and become an important clinical reference.
The fly in the ointment was in all HL cases, the cardiac ultrasound data parameters are not available when normal, such as the size of the left ventricular diameter, the physiological regurgitation of the valve. There are individual differences in these data, so it is impossible to compare before and after the individuals themselves, which may have a certain impact on the prognostic evaluation of these disease parameters. In addition, the case of coronary artery dilation does not have the data before the onset, so when the dilated coronary artery diameter returns to the normal range, whether the data is different from the coronary artery diameter when it is normal is not known, because the inner diameter of the coronary artery itself has individual differences. On the other hand, for the HL that recovered, the follow-up could not be continued for one year, so that the later heart changes could not be observed.