The influence of the peripheral reflection wave on left ventricular hypertrophy in patients with essential hypertension.

The objective of this study was to clarify the relationship between afterload, which consists mainly of the vascular reflection wave, and left ventricular hypertrophy in patients with untreated essential hypertension using the fingertip photoplethysmogram (PTG) and second derivative wave (SDPTG) methods, the simplest and most convenient tools for pulse wave analysis. The augmentation index (AI) is defined as the ratio of the height of the late systolic peak, augmented by the peripheral reflection wave, to that of the early systolic peak caused mainly by left ventricular ejection in the pulse. Increased AI of the PTG and negative d/a, obtained by multiplying the ratio of the late re-decreasing wave (d wave) to the initial positive wave (a wave) of the SDPTG by -1, have the same meaning as increased ascending aortic AI. The left brachial artery blood pressure was measured in 60 patients. The PTG and SDPTG of the right second finger were recorded by a digital photoplethysmograph. The left ventricular mass index (LVMI) was investigated by ultrasonography. Subjects were assigned to one of two groups: a low AI (AI of PTG<1.6; group 1) or a high AI (AI of PTG> or =1.6; group 2) group. LVMI was significantly higher in group 2 than in group 1. In the study group as a whole, the LVMI was positively correlated with both the AI of PTG (r=0.60, p<0.0001) and negative d/a (r=0.63, p<0.0001). An increase in the LVMI was seen in subjects with an augmented late systolic component in the waveform. It was concluded that an increase in the peripheral reflection wave on the left ventricle is one of the important factors causing cardiac hypertrophy in patients with hypertension.

Second derivative of photoplethysmogram in children and young people.

The characteristics of the second derivative of the photoplethysmogram (SDPTG) were clarified in children and young people, and the factors affecting the SDPTG wave pattern were examined. The study group comprised 775 healthy subjects aged 3-20 years (mean, 10+/-5). The blood pressure of the left brachial artery was determined in the resting sitting position and then the fingertip PTG and the SDPTG were automatically measured using a digital photoplethysmograph, with the sensor located at the cuticle of the second digit of the right hand. The values used were the b/a, c/a, d/a, and e/a ratios, and the SDPTG aging index (SDPTG-AI). With increasing age, the systolic blood pressure and height increased (r = 0.52, 0.92). Aging decreased the b/a ratio and SDPTG-AI (r = -0.58, -0.67) and increased the c/a and e/a ratios (r = 0.42 and 0.42). There was no significant correlation between blood pressure and indices of SDPTG. As height increased, the b/a ratio and SDPTG-AI decreased (r = -0.57, -0.71), whereas the c/a and e/a ratios increased (r = 0.42 and 0.46). In males the SDPTG-AI decreased with age from 3 to 18 years and then increased, and in females it decreased with age from 3 to 15 years and then increased. Overall, the SDPTG-AI decreased with age between 3 and 18 years and then increased, forming a J curve. In the children's and young people's SDPTG, the b/a and SDPTG-AI decreased and the c/a and e/a ratios increased with age. The length of the vascular system and the inner diameter and wall thickness of vessels may modify the SDPTG wave pattern in the growth period. Thereafter, as the effects of these factors decrease, the increase in intravascular pressure and decreasing wall elasticity due to aging may affect the wave pattern.

Exercise performance in children with hyperthyroidism.

An attempt was made to define exercise performance in children with untreated hyperthyroidism using treadmill stress testing. Data were obtained for five female patients and the results were compared with those obtained for 16 normal female subjects. There were no significant differences at rest between the hyperthyroidism group and the control group in oxygen uptake, minute ventilation and respiratory rate. On the other hand, heart rate in the hyperthyroidism group was significantly higher than that in the control group. During exercise, there were significant differences between the two groups in oxygen uptake, heart rate, minute ventilation and respiratory rate. Hyperthyroid patients did not show an abrupt increase in heart rate during the first 30 s of exercise. Exercise stress testing can therefore reveal cardiopulmonary abnormalities that are not evident at rest in children with hyperthyroidism.