Product of heart rate and first heart sound amplitude as an index of myocardial metabolic stress during graded exercise.

BACKGROUND: The double product (DP) breakpoint of heart rate (HR) and systolic blood pressure has been identified as coincident with anaerobic threshold (AT), but there are no simple methods for measuring cardiac metabolic stress (CMS) during an exercise test. It was hypothesized that the DP of HR and the amplitude of the first heart sound (AHS1) (DP-AHS1) would reflect CMS, and thus, the breakpoint in the DP-AHS1 (DPBP-AHS1) could be an alternative method for determining AT. METHODS AND RESULTS: Subjects (age range, 18-73 years) were recruited to perform a graded exercise test on a cycle ergometer with continuous monitoring of DP-AHS1, with left ventricular pressure (LVP; experiment 1, Ex1), plasma catecholamine and blood lactate (experiment 2, Ex2) and gas exchange (experiment 3, Ex3). Ex1: in all subjects there was a strong correlation between AHS1 and LVdP/dtmax (r=0.94-0.98), and between the DP-AHS1 and the triple product of HR, LVdP/dtmax, and max LVP (r=0.98-0.99). Ex2: DP-AHS1 was strongly correlated with adrenaline (r=0.97-1.00) and lactate (r=0.96-1.00) levels in all subjects. Ex3: there was a strong correlation between DPBP-AHS1, AT and maximum oxygen consumption. CONCLUSIONS: The present simple measure of DP-AHS1 can reflect plasma adrenaline and lactate levels during graded exercise testing. Further, DPBP-AHS1 is a surrogate marker of AT and a good index of functional aerobic capacity.

Wireless blood velocity spectra measurement system for healthcare evaluation: reference data.

The aim of the present study was to determine the blood velocity and its indices in common carotid artery (CCA) as reference value for clinical and healthcare application using the constructed portable wireless Doppler blood flow velocimeter system. Evaluation of CCA blood velocity waveforms was performed in 202 healthy volunteers in the age range of 20 to 69 years. Multivariate analysis was used to determine the relationship between the fixed factor and the outcome hemodynamic variables after adjustment for the related covariates. Results show a general age-related decrease in flow velocities and change in the velocity waveform. There is also a gender difference in velocity indices, except for peak systolic blood velocity. Gender difference is also found in systolic and pulse blood pressures. The findings suggest that waveform indices provide a more reliable evaluation of effects of aging and gender on CCA flow. In conclusion, normal CCA blood velocity parameters are determined in a total of 202 healthy volunteers between the third and seventh age decade after adjustment for gender and exercise effects. Findings may contribute to improved means of healthcare monitoring and clinical evaluation.

Effect of gender on blood flow velocities and blood pressure: role of body weight and height.

Aging and gender alter arterial hemodynamic function. Gender-related differences in body size may affect the arterial hemodynamics such as systolic blood pressure, wave reflection and pressure wave propagation. To assess the possibility that the differences of carotid blood velocities and brachial blood pressure in women are related to body size, we investigated the arterial hemodynamics in 50 healthy young adults (30 men, 20 women) between the age ranges of 20 to 29 years old. Blood velocities are characterized to 5 components of velocity waveforms as peak systolic (S1), second systolic (S2), incisura between systole and diastole (I), peak diastolic (D) and end-diastolic velocity wave (d). As the most pronounced systolic blood pressure is lower in young women than men (P<0.05). Women have higher diastolic velocity components and second systolic velocity, but have lower systolic velocity compared to men. From that, women have a significant greater wave reflection, smaller vascular resistive and lower vascular elastic recoil than in men. Greater body weight is associated with higher blood pressures (P<0.05) and lower blood velocities (P<0.05). Shorter body height affects not only the increased velocity wave reflection index (r= -0.519, P>0.0001), but also the decrease of peripheral vascular resistive index (RI) and arterial vascular elastic recoil index (r= 0.463, P<0.0001; r= 0.481, P<0.0001, respectively). In conclusion, body size influences blood pressure and velocity regulations in the young population.

Effects of aging and exercise training on the common carotid blood velocities in healthy men.

An age-related alteration in the cardiovascular response to exercise training are evident. The purpose of the study was to investigate the effects of exercise and age on blood velocities in common carotid artery in 82 healthy men between the age ranges of 21 to 67 years old. Blood velocities are characterized to five components of velocity waveforms as peak systolic (S1), second systolic (S2), incisura between systole and diastole (I), peak diastolic (D) and end-diastolic velocity wave (d). Decrease of blood velocities in peak systolic (r= -0.711, P<0.0001) and in peak diastolic velocities (r= -0.521, P<0.0001) with aging are improved and partially restore in particularly older men. The velocity ratio of S2/S2-1 as a reflection index increase with age (r= 0.797, P<0.0001), however is smaller in exercise-trained older compared with sedentary peers. The ratio of 1-I/D as a vascular elastic recoil index decrease with aging (r= -0.640, P<.0001), but is relatively higher in exercise-trained men. Exercise training improves the age-related deterioration in blood velocities and its indices in healthy men. In the further investigations, the assessment of aerobic fitness and vascular aging has potential by using the criteria of peak systolic and peak diastolic, and its indices.

A novel parallel algorithm for large-scale Fock matrix construction with small locally distributed memory architectures: RT parallel algorithm.

We developed a novel parallel algorithm for large-scale Fock matrix calculation with small locally distributed memory architectures, and named it the "RT parallel algorithm." The RT parallel algorithm actively involves the concept of integral screening, which is indispensable for reduction of computing times with large-scale biological molecules. The primary characteristic of this algorithm is parallel efficiency, which is achieved by well-balanced reduction of both communicating and computing volume. Only the density matrix data necessary for Fock matrix calculations are communicated, and the data once communicated are reutilized for calculations as many times as possible. The RT parallel algorithm is a scalable method because required memory volume does not depend on the number of basis functions. This algorithm automatically includes a partial summing technique that is indispensable for maintaining computing accuracy, and can also include some conventional methods to reduce calculation times. In our analysis, the RT parallel algorithm had better performance than other methods for massively parallel processors. The RT parallel algorithm is most suitable for massively parallel and distributed Fock matrix calculations for large-scale biological molecules with more than thousands of basis functions.