In isolated right atria of the rabbit heart, we studied the activation pattern within the sinus node, using the microelectrode technique. After the electrophysiological experiments, the preparations were subjected to a correlative morphological investigation, using light or electron microscopy. Different criteria for defining the dominant pacemaker were compared. A group of at least 5000 cells, located within the central part of the node where the most characteristic tissue architecture was found, was considered to be responsible for generation of the impulse. At the ultrastructural level, this leading cell group appeared to be part of a larger uniform cell group. The number of gap junctions observed suggests that all nodal cells are coupled by these structures. Toward the periphery, the excitation wave was propagated preferentially in an oblique cranial direction toward the crista terminalis. Neither morphologically nor electrophysiologically specific pathways were found for the conduction, but the preferential direction could be explained by the tissue architecture.

Abstract-A high serum total homocysteine (tHcy) level is an independent risk factor for cardiovascular disease. Because it is not known whether the strength of the association between hyperhomocysteinemia and cardiovascular disease is similar for peripheral arterial, coronary artery, and cerebrovascular disease, we compared the three separate risk estimates in an age-, sex-, and glucose tolerance-stratified random sample (nϭ631) from a 50-to 75-year-old general white population. Furthermore, we investigated the combined effect of hyperhomocysteinemia and diabetes mellitus with regard to cardiovascular disease. The prevalence of fasting hyperhomocysteinemia (Ͼ14.0 mol/L) was 25.8%. After adjustment for age, sex, hypertension, hypercholesterolemia, diabetes, and smoking, the odds ratios (ORs; 95% confidence intervals) per 5 -mol/L increment in tHcy were 1.44 (1.10 to 1.87) for peripheral arterial, 1.25 (1.03 to 1.51) for coronary artery, 1.24 (0.97 to 1.58) for cerebrovascular, and 1.39 (1.15 to 1.68) for any cardiovascular disease. After stratification by glucose tolerance category and adjustment for the classic risk factors and serum creatinine, the ORs per 5 -mol/L increment in tHcy for any cardiovascular disease were 1.38 (1.03 to 1.85) in normal glucose tolerance, 1.55 (1.01 to 2.38) in impaired glucose tolerance, and 2.33 (1.11 to 4.90) in non-insulin-dependent diabetes mellitus (Pϭ.07 for interaction). We conclude that the magnitude of the association between hyperhomocysteinemia and cardiovascular disease is similar for peripheral arterial, coronary artery, and cerebrovascular disease in a 50-to 75-year-old general population. High serum tHcy may be a stronger (1.6-fold) risk factor for cardiovascular disease in subjects with non-insulin-dependent diabetes mellitus than in nondiabetic subjects. (Arterioscler Thromb Vasc Biol. 1998;18:133-138.)Key Words: homocysteine Ⅲ non-insulin-dependent diabetes mellitus Ⅲ cardiovascular disease Ⅲ epidemiology R etrospective and prospective studies have demonstrated that hyperhomocysteinemia is a risk factor for cardiovascular disease that is independent of classic risk factors such as smoking, hypercholesterolemia, diabetes mellitus, and hypertension. [1][2][3][4] In a recent meta-analysis, 1 the association between hyperhomocysteinemia and peripheral arterial disease (summary OR, 6.8) was considerably stronger than with coronary artery and cerebrovascular disease (ORs, 1.8 and 1.5). The summary estimate of the association between hyperhomocysteinemia and peripheral arterial disease, however, was inferred from one population-based study, 5 which consisted of only men, and two hospital-based studies. 6,7 Therefore, to further investigate this issue, we compared the risk estimates of peripheral arterial, coronary artery, and cerebrovascular disease in a random sample of a 50-to 75-year-old general white population.A recent large study showed that the risk of cardiovascular disease was especially high among subjects with hyperhomocysteinemia who also smoked or had hyperte...

No abstract

We investigated the cross-sectional association between peripheral arterial disease and glycaemic level in an age, sex, and glucose tolerance stratified random sample from a 50-74-year-old Caucasian population. Subjects treated with oral hypoglycaemic agents or insulin were classified as having known diabetes mellitus (KDM) (n = 67). Using two oral glucose tolerance tests, and based on World Health Organisation criteria, all other participants were categorized as having a normal (NGT) (n = 288), an impaired (IGT) (n = 170), or a diabetic (NDM) (n = 106) glucose tolerance. Prevalence rates of ankle-brachial pressure index less than 0.90 were 7.0%, 9.5%, 15.1% and 20.9% in NGT, IGT, NDM and KDM subjects, respectively (chi-square test for linear trend: p < 0.01). Prevalence rates of any peripheral arterial disease (ankle-brachial pressure index < 0.90, at least one monophasic or absent Doppler flow curve or vascular surgery) were 18.1%, 22.4%, 29.2% and 41.8% in these categories (chi-square test for linear trend: p < 0.0001). The prevalence of any peripheral arterial disease was higher in KDM and NDM than in NGT (p < 0.03, p < 0.0001, respectively), whereas no statistically significant difference was demonstrated between IGT and NGT. The same applied when using the ankle-brachial pressure index criterion. Logistic regression analyses showed that any arterial disease was significantly associated with HbA1c, fasting and 2-h post-load plasma glucose after correction for cardiovascular risk factors (odds ratios and 95% confidence intervals 1.35; 1.10-1.65 per %, 1.20; 1.06-1.36 and 1.06; 1.01-1.12 per mmol/l, respectively), whereas it was not associated with fasting and 2-h post-load specific insulin. Ankle-brachial pressure indices were not associated with either plasma glucose parameters or insulin in univariate or multivariate analyses. In conclusion, parameters of glucose tolerance are independently associated with any peripheral arterial disease, whereas insulin is not.

In conclusion, we suggest that patients with medial and/or recurrent ulceration should receive surgery combined with ambulatory compression therapy. A dedicated center should provide care for those patients.