Short-Term Effect of High Dose of Vitamin C on Coronary Flow Velocity and Coronary Flow Reserve in Healthy Young Non-Smoker Men

BACKGROUND AND OBJECTIVES: Vitamin C, water-soluble antioxidant, has been reported to restore coronary microcirculatory responsiveness and impaired coronary flow reserve in smokers. However, the effect of high dose of vitamin C on coronary circulation is unclear in nonsmokers. METHODS: We used transthoracic echocardiography to measure the coronary flow reserve, an integrated measure of coronary flow in 20 male healthy nonsmokers (26+/-3 years) before and after administration of the high dose of vitamin C. RESULTS: The coronary peak diastolic velocity was increased by 14.8% after administration of antioxidant vitamin C, whereas the coronary flow reserve did not changed. CONCLUSION: High dose of vitamin C acutely increases the coronary flow velocity without restoration of coronary flow reserve in male healthy nonsmokers.

The Usefulness of Color M-mode Doppler Echocardiographic Indices in the Assessment of Left Ventricular Diastolic Function

BACKGROUND AND OBJECTIVES: Early color M-mode Doppler flow propagation (Vp) has been used to distinguish pseudonormal from normal diastolic filling patterns. However, the role of other indices, including the late diastolic propagation velocity (Ap) and time delay of mitral flow propagation (VpTD and ApTD), is not clear. SUBJECTS AND METHODS: Doppler echocardiographic examinations were performed in 89 patients (60.6+/-9.9 years, male 59.6%), with an ejection fraction > or =40%, who were admitted for diagnostic coronary angiography. The clinical diagnoses on admission were stable angina (41.6%), unstable angina (30.3%), old myocardial infarction (24.7%) and atypical chest pain (3.3%) The diastolic filling patterns, as confirmed by mitral inflow and pulmonary venous flow, were compared with the Ap, VpTD and ApTD indices using color M-mode Doppler echocardiography. RESULTS: The age, left ventricular ejection fraction, left ventricular end diastolic and end systolic dimensions, the left atrial size, and the E'and A'velocities of the mitral annulus tissue Doppler were significantly different between patients with normal and abnormal diastolic filling patterns. In patients with normal filling, impaired relaxation and pseudonormalized filling patterns, the VpTD were 63.1+/-14.9, 85.2+/-25.5 and 107.8+/-36.8 ms (p<0.001), the E/Vp were 1.3+/-0.4, 1.6+/-0.6 and 3.1+/-0.7 (p<0.001), and the E/VpTD were 1.2+/-0.5, 0.7+/-0.2 and 0.9+/-0.4 (p<0.001), respectively. The Ap and ApTD showed significant differences between patients with normal and pseudonormalized filling patterns (Ap 58.3+/-23.5 vs. 36.2+/-15.1, p=0.000; ApTD 47.1+/-19.5 vs. 66.7+/-22.2, p=0.001). The PVa duration, an index that depends on the left ventricular end-diastolic pressure, was the most important independent predictor for ApTD from a multiple regression analysis (R2=71.4%). CONCLUSION: The color M-mode Doppler indices, Ap, VpTD and ApTD, are new diagnostic parameters for diastolic dysfunction.