Wu Tl

Circadian variations of atrial natriuretic peptide in normal people and its relationship to arterial blood pressure, plasma renin activity and aldosterone level

To investigate the circadian variations of plasma atrial natriuretic peptide (ANP) and its relationship to arterial blood pressure, plasma renin activity and aldosterone level, we determined 24-h blood pressure in 14 healthy volunteers. Plasma ANP concentration, renin activity and aldosterone levels were measured every 3 h by radioimmunoassay. We found no significant circadian variation of plasma ANP level (pg/ml) (daytime level, 62 +/- 24 vs. nighttime level, 57 +/- 19, P = 0.146) and plasma renin level (ng/ml/h) (1.32 +/- 0.78 vs. 1.15 +/- 0.57, P = 0.148), but there was diurnal change of blood pressure (mmHg) (systolic, 122 +/- 7 vs. 116 +/- 11, P < 0.001; diastolic, 80 +/- 11 vs. 72 +/- 11, P = 0.025) and plasma aldosterone level (pg/ml) (86 +/- 42 vs. 62 +/- 37, P < 0.001). The blood pressure and aldosterone levels reached maxima (11:00 h and 08:00 h, respectively) before that of ANP (17:00 h) and then decreased together until the nadir at 02:00 h. This might indicate that elevation of arterial blood pressure and plasma aldosterone level stimulate release of ANP under normal physiological conditions.

Vectorcardiographic features of acute right ventricular infarction

A total of seven patients with acute inferior or inferior-posterior transmural myocardial infarction who had cardiac scintigraphically confirmed right ventricular (RV) involvement was studied. Series of vectorcardiographic tracings were taken using the Frank lead reference system from the second day after onset of acute symptoms; we found that in patients with acute inferior and RV infarction, the magnitude of the planar ST vector was greater than or equal to 0.15 mV and the projection of the ST vector pointed either to the right-anterior or right-posterior direction in the horizontal (H) plane. The serial spatial ST vector changed its direction either: 1) from right-anterior-inferior octant to right-posterior-inferior octant or vice versa; or 2) from right-posterior-inferior octant to right-anterior-superior octant. The larger the magnitude of the rightward ST vector, especially right-anterior direction in the H plane, the greater the probability of acute RV infarction. In patients with acute inferior-posterior and RV infarction, the magnitude of the ST vector in the H plane was greater than or equal to 0.2 mV. The spatial ST vector pointed to the right-posterior-inferior octant and its direction did not change from the original octant in the serial tracings during the course of the acute stage. Our data suggest that vectorcardiography--a non-invasive, non-nuclear polluting, and economical method--has shown great potential to become, in the near future, the primary non-invasive diagnostic test of choice for acute RV infarction.