Chin-Hsiao Tseng
Department of Internal Medicine,
National Taiwan University Hospital, Taipei,
Taiwan
Chin-Hsiao Tseng
Department of Internal Medicine,
National Taiwan University Hospital, Taipei,
Taiwan
| Blackfoot disease is an endemic peripheral vascular disease confined to the southwestern coast of Taiwan. Its incidence has declined since the implementation of tap water in that area some 20-30 years ago. The etiology of this disease is still not fully known. However, arsenic and humic substance have been suggested. During the past few years, we have carried out a series of studies examining the subclinical and microcirculatory defects which might occur before clinical manifestation of blackfoot disease. By measuring the ankle and brachial systolic pressures before and after a treadmill exercise in comparable groups of seemingly normal subjects living in the blackfoot disease-hyperendemic villages and a non-endemic area as control, we demonstrated an abnormal drop of ankle pressures in subjects living in the endemic area, which indicated minor arterial insufficiency before the development of blackfoot disease. In a similar case-control design, by using laser Doppler flowmetry, we also demonstrated early defects in microcirculation in the seemingly normal subjects living in these villages after more than thirty years' exposure to the artesian well water. The defect was independent on the minor arterial insufficiency and was considered as probably due to capillary closure, reduction of vasodilating substances, irresponsiveness to vasodilatation or impairment in sensory nerve function. The causal effect of arsenic on the development of peripheral vascular disease was examined with the consideration of the drawbacks found in previous studies. By using an objective tool of Doppler ultrasound, three indices of long-term arsenic exposure, and adjustment for confounding effects of well-established risk factors for coronary atherosclerosis (including six items of lipid profiles), we demonstrated a dose-response relationship between arsenic exposure and peripheral vascular disease in a group of adults without full-blown blackfoot disease. In conclusion, 1) in the blackfoot disease-hyperendemic villages characterized by long-term arsenic exposure from drinking water, early arterial and microcirculatory defects could be found in seemingly normal subjects; 2) peripheral vascular disease in these endemic villages was associated with arsenic exposure in an independent and dose-dependent pattern. (J Intern Med Taiwan 1999;10:88-92) |