BackgroundKawasaki disease is recognized as the most common cause of acquired heart disease in children in the developed world. Clinical, epidemiologic, and pathologic evidence supports an infectious agent, likely entering through the lung. Pathologic studies proposing an acute coronary arteritis followed by healing fail to account for the complex vasculopathy and clinical course.Methodology/Principal FindingsSpecimens from 32 autopsies, 8 cardiac transplants, and an excised coronary aneurysm were studied by light (n=41) and transmission electron microscopy (n=7). Three characteristic vasculopathic processes were identified in coronary (CA) and non-coronary arteries: acute self-limited necrotizing arteritis (NA), subacute/chronic (SA/C) vasculitis, and luminal myofibroblastic proliferation (LMP). NA is a synchronous neutrophilic process of the endothelium, beginning and ending within the first two weeks of fever onset, and progressively destroying the wall into the adventitia causing saccular aneurysms, which can thrombose or rupture. SA/C vasculitis is an asynchronous process that can commence within the first two weeks onward, starting in the adventitia/perivascular tissue and variably inflaming/damaging the wall during progression to the lumen. Besides fusiform and saccular aneurysms that can thrombose, SA/C vasculitis likely causes the transition of medial and adventitial smooth muscle cells (SMC) into classic myofibroblasts, which combined with their matrix products and inflammation create progressive stenosing luminal lesions (SA/C-LMP). Remote LMP apparently results from circulating factors. Veins, pulmonary arteries, and aorta can develop subclinical SA/C vasculitis and SA/C-LMP, but not NA. The earliest death (day 10) had both CA SA/C vasculitis and SA/C-LMP, and an “eosinophilic-type” myocarditis.Conclusions/SignificanceNA is the only self-limiting process of the three, is responsible for the earliest morbidity/mortality, and is consistent with acute viral infection. SA/C vasculitis can begin as early as NA, but can occur/persist for months to years; LMP causes progressive arterial stenosis and thrombosis and is composed of unique SMC-derived pathologic myofibroblasts.

Three cases of unilateral right-sided pulmonary venous atresia were evaluated over an 18-year period. These bring the total number of cases to 25 in the literature. The clinical presentation of all these patients was similar and consisted of recurrent pulmonary infections, asthma-like symptoms, and exercise intolerance. The patients presented in 1982 (patient 1, a 12-year-old boy), 1994 (patient 2, a 9-year-old girl), and 1999 (patient 3, a 13-year-old boy). All patients were evaluated with a chest roentgenogram, and patients 1 and 2 had a ventilation and perfusion scan. Patients 1 and 3 also had cardiac catheterization and pulmonary angiography. Patient 2 had a magnetic resonance imaging study of the chest. Only patient 3 had wedge pulmonary angiography. Although a rare congenital defect, this diagnosis should be strongly suspected based on the typical clinical presentation and the preliminary studies, such as the chest roentgenogram and ventilation and perfusion scan. However, for definitive diagnosis, cardiac catheterization with wedge pulmonary angiography is necessary. Anastomosis of the atretic pulmonary veins to the left atrium is a theoretical consideration. However, this may not be feasible due to pulmonary venous anatomy or significant pulmonary dysfunction with pulmonary vascular changes. In these circumstances, we recommend performing pneumonectomy to remove the nidus for repeated bouts of pulmonary infections, to eliminate the left-to-right shunt, and to eliminate the dead space contributing to exercise intolerance.

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