Changes in endothelium-derived vascular regulatory factors during dobutamine-stress-induced silent myocardial ischemia in patients with Kawasaki disease

Sudden Cardiac Death in the General Population: Can We Improve Risk Stratification and Prevention?

A total of 15 to 20% of deaths worldwide are sudden (within 1 hour of symptom onset). Our ability to predict and prevent sudden cardiac death (SCD) in the general population, in which 85% have no known organic heart disease (OHD) or stable OHD with left ventricular ejection fraction >40%, is limited to poor. The purpose of this commentary is to suggest a new approach to SCD in this population. Oxidative stress is a common thread in development and progression of the major cardiac diseases associated with SCD. It has a profound adverse effect upon heart rate variability (HRV), sympathetic tone (S), and parasympathetic tone (P). Recently, developed technology finally has allowed accurate measures of S and P. Using this technique, the general population can be screened, those at risk for SCD can be identified with a higher degree of success, and preventative measures instituted. For example, in 133 geriatric type 2 diabetics with S and/or P abnormalities upon screening, the potent and natural antioxidant (r)α lipoic acid reduced SCD (relative risk reduction) 43% ( p  = 0.0076), mean follow-up 6.31 years. Diabetes mellitus patients have high glycemic oxidative stress. Addressing oxidative stress S and P abnormalities can reduce SCD. S and P screening of the general population will be discussed.

Evaluation by high-resolution ultrasonography of endothelial function in brachial artery after Kawasaki disease and the effects of intravenous administration of vitamin C

Previous studies in patients with a history of Kawasaki disease (KD) have focused on the endothelial function of the coronary arteries and that of the systemic arteries is not fully understood. Furthermore, the effect of vitamin C on systemic vascular endothelial function after KD has not yet been elucidated. In the present study, 39 patients (age, 7.1 +/- 2.7 years) at 1-10 years after acute KD were compared with 17 matched healthy subjects (7.0 +/- 3.1 years). High-resolution ultrasonography was used to analyze brachial artery responses to reactive hyperemia (with increased flow causing endothelium-dependent dilation) and sublingual nitroglycerin (causing endothelium-independent dilation) after KD, and to investigate whether the acute administration of vitamin C can restore systemic endothelial dysfunction. The percent change in diameter of the brachial artery induced by reactive hyperemia in the patients with a history of KD (6.2 +/- 3.9%) was significantly less than that in the control group (14.1 +/- 6.8%, p < 0.0001). No significant difference could be found in the percent change in diameter induced by sublingual nitroglycerin between the controls (33.2 +/- 13.7%) and the patients (30.6 +/- 9.2%, p = 0.49). There was no significant difference in percent change in diameter of the brachial artery induced by reactive hyperemia between the patients who received gamma globulin (6.0 +/- 4.0) and those who did not (7.9 +/- 3.3, p = 0.33). Intravenous infusion of vitamin C significantly increased the percent change in diameter of the brachial artery induced by reactive hyperemia in 19 patients with history of KD (6.6 +/- 3.5% to 13.0 +/- 5.5%, p < 0.0001). After placebo administration in 20 patients with history of KD there was no significant increase in the percent change in the diameter of the brachial artery induced by reactive hyperemia (6.5 +/- 4.5% to 7.3 +/- 4.9%, p = 0.20). The decreased percent change in the diameter of the brachial artery induced by reactive hyperemia in patients with a history of KD compared with the healthy children indicates that systemic endothelial dysfunction exists after KD. Although it is not influenced by early treatment with high-dose gamma globulin in the acute stage of KD, systemic vascular endothelial function can be restored by acute intravenous administration of vitamin C.

Dobutamine stress radionuclide ventriculography reveals silent myocardial dysfunction in Kawasaki disease

Dobutamine (DOB) stress radionuclide ventriculography (RVG) is proposed for evaluating left ventricular performance in patients with Kawasaki disease (KD). Dobutamine stress RVG, up to 15 microg x kg(-1) x min(-1), was performed in 40 patients with a history of KD, some of whom had a perfusion defect (PD group) on dipyridamole stress thallium-201 myocardial imaging, some of whom had no perfusion defects (NPD group), and some of whom had no coronary artery lesions (C group). No significant differences in either systolic or diastolic indices of the left ventricle at rest were observed between the 3 groups. Although hemodynamic responses were similar in all patients after DOB stress, early diastolic index of the first third filling fraction decreased only in the PD group and was significantly lower in this group compared with the C group (p<0.01). The asynchrony index increased significantly in those patients with coronary stenosis after DOB stress (p<0.05). No serious side-effects were observed during the study. Even late after onset, patients with myocardial ischemia as a result of KD still had impaired early diastolic filling and asynchronous relaxation of the left ventricle. As an alternative to exercise testing, DOB stress RVG is a safe and promising means for serially evaluating left ventricular performance in patients with KD.