Abstract 48: Small Arteritis is the Basic Pathology of Kawasaki Disease

Abstract

Introduction: Pathologic processes of two features in Kawasaki disease (KD) have not been elucidated. The one is the preponderance of aneurysms in the main coronary artery. The other is the discontinuity in the process of the vasculitis between those of microvessels and small arteries, and those of medium-sized to large arteries. Hypothesis: We assessed the hypothesis that arteritis of the vasa vasorum, which we described for the first time, plays a key role in the preponderance of aneurysms in the main coronary artery in KD. Methods: We examined the relationship between patient age at onset of KD and the distance ratio of the aneurysm in the left main coronary artery (LMCA) to clarify the role of arteritis of the coronary vasa vasorum, originated from the atrial and ventricular branches of the peripheral coronary artery, in the ischemia at the media of LMCA. The distance ratio Y was defined as D1/D2 х 100, where D1 and D2 are the distances from the left coronary ostium to the proximal point of the aneurysm and to the bifurcation into the left anterior descending and left circumflex artery, respectively. We then studied the relations between cardiogenic shock and extracardiac aneurysm, and coronary aneurysm in our cases and those of literatures. Results: The mean distance ratio of 56 aneurysms correlated with age, similar to the development of the coronary vasa vasorum: Y = 49.75383 - 3.3739X, P = 0.002987, R = 0.356. Cardiogenic shock which indicates severe interstitial myocarditis and severe arteritis of the coronary vasa vasorum occurs in the 1st week of the illness and is followed by aneurysm formation in LMCA. Extracardiac aneurysm due to severe arteritis of its vasa vasorum associates with severe arteritis of the coronary vasa vasorum originated from the aorta which may induce dilatation at the proximal portion of LMCA. Thus, aneurysm in LMCA complicated with extracardiac aneurysm reveals its proximal extension. In conclusion, these findings may contribute to understand morphogenesis and to investigate the treatment on KD.