Statistical analysis of 100 successive RR interval time in ECG, mean heart rate was carried out in 3 groups. The 1st group consisted of 23 healthy men, aged 19.3. The 2nd group consisted of 8 men, aged 21,6 and suffered from inconciousness during working time. The 3rd group consisted of 6 men, aged 19.2 with bad occupational adaptation. Results: heart rate index of 2nd and 3rd groups at rest clearly represented functional strain in comparison with that of 1st group were decreased, mean HR and SI were increased. After 30 and 60 minutes of stricly standing, all index of 3 groups were significantly greater than that at rest, but the index variation of the 1st group were higher than in 2nd and 3rd groups.
Analysis ; Heart Rate ; physiology

OBJECTIVETo compare the heart rate variability (HRV) measurements between ballistocardiogram (BCG) and electrocardiography (ECG).

METHODSThe signals of BCG and ECG of 21 patients were collected synchronously. JJ intervals of BCG and RR intervals of ECG were used to calculate the cardiac periods. The parameters of HRV analysis were calculated in time domain analysis, frequency domain analysis and nonlinear analysis. The results derived from BCG and ECG were compared.

RESULTSThe parameters of HRV analysis calculated from BCG and ECG had high similarity. The correlation coefficients of SDNN, TP, LF, HF and SD2 between the BCG and ECG methods were high (r = 1). The correlation coefficients of rMSSD and SD2 were 0.99 and of PNN50 and LF/HF were 0.98 between the two methods. HRV analysis results derived from the two methods were similar (P > 0.05).

CONCLUSIONHRV could also be measured reliably by calculating the JJ interval from BCG.

Heart ; physiology ; Humans ; Stress, Physiological

Animals ; Chick Embryo ; physiology ; Electrocardiography ; methods ; Heart ; embryology ; physiology ; Heart Rate ; physiology

AIMThe purpose of this experiment was to investigate the cardiac physiological characteristics for adaptation to high-altitude hypoxia in chickens.

METHODSTibetan, Dwarf Recessive White and Shouguang chickens were fed at low-and high-altitude, and measurements were made in heart weights, lactic acid (LA), lactate dehydrogenase (LDH), and succinate dehydrogenase (SDH) at the age of 10 weeks.

RESULTSThe results showed that Tibetan chickens at high-altitude had lower heart weight and LA content, and similar LDH activity, and higher SDH activity when compared to Dwarf Recessive White and Shouguang chickens.

CONCLUSIONIt was concluded that the cardiac mechanisms of high-altitude hypoxic adaptation in Tibetan chickens were increasing neither heart weight, nor level of anaerobic metabolism, but the higher SDH activity was significant to the adaptation. The SDH was a symbol enzyme for hypoxic adaptation in Tibetan chicken.

To determine the role of vagi in heart rate variability, conscious rabbits were employed and electrocardiogram was recorded under conditions of bilateral vagi intact, unilateral vagotomy, and bilateral vagotomy. The variability of RR intervals (RRI) was analyzed using power spectrum and approximate entropy (ApEn). The results showed that the values of high frequency power (HF) component, low frequency power (LF) component and ApEn in animals with bilateral vagi intact were the highest, but the LF/HF ratio was the lowest; unilateral vagotomy decreased ApEn, right vagotomy increased LF/HF ratio but left vagotomy did not; the LF/HF ratio increased while ApEn decreased significantly in animals with bilateral vagotomy. It is suggested that the variability of RRI is mainly regulated by the vagi and the role of right vagi is more important than that of the left. When measuring heart rate variability, the results obtained with conventional method are consistent with those with nonlinear method.
Animals ; Entropy ; Heart Rate ; physiology ; Male ; Rabbits ; Vagus Nerve ; physiology

The wide frequency band ECG (WFB-ECG) was recorded in 33 (anesthetized) normal pigeons by the microprocessor ECG system (made in Nanjing University) with a wide-frequency response (0-1000 Hz), a high-speed sweep (up to 1401 mm/s) and a high sensitivity (up to 28 mm/mV). The recording methods for limb leads in the pigeon were the same as those in man, except that the needle electrodes (made by No.5 needles) were subcutaneously inserted in the bases of the wings and in the legs. We studied the features of time domain and power spectrum of pigeons WFB-ECG. It presents P, R, S and T waves, but no Q wave, basically similar to the results from Aves described by Sturkie. But there are still many characters that were not be recorded on the conventional ECG: (1) the main QRS complex is inverted and forms the type of rS or rSr , no Q wave in leads II, III, aVF, and the S-T segment is absent, which is different from that of humans. The T wave is upright in leads II, III, and aVF (except one), in agreement with that of man. But in lead aVR, the main QRS complex is upright and forms the type of Rs, and the T wave is inverted without any exception. There is a large notch on the upstroke of S wave without any exception. The amplitude of the notch is 0.413+/-0.133 mV and the duration is 9.733+/-1.291 ms in lead II. (2) The ratio of duration of P wave to P-R segment is about 0.8, lower than that of humans (1.0-1.6), but higher than that of mice (0.4). (3) The low frequency signals (0-80 Hz) are prominent. The relative power content of high frequency range of QRS in lead II is: 100-1000 Hz: (10.181+/-7.443)%; 80-300 Hz: (15.418+/-10.579)%. (4)The QRS vector loop in the frontal plane lies between -90 degrees and -180 degrees. The electrical axis of QRS complex averages -118 +/-10 (ranges from -96 degrees to -136 degrees). The reason that position of vector loop and the direction of main wave of QRS in the pigeon are different from human s and rodent s is probably that the Purkinje fibers cross the whole ventricular wall and terminate in the subepicardium in Aves including pigeons . After the impulses coming from the sinoatrial node reach the ventricular muscles, the subepicardium is depolarized before the endocardium. However in human s and rodent s, the Purkinje fibres only reach one-forth to one-second of the whole thickness from the endocardium to the epicardium, the subendocardium is depolarized before the subepicardium.
Animals ; Columbidae ; physiology ; Electrocardiography ; Female ; Heart ; physiology ; Male

Altitude ; Exercise/physiology* ; Heart Rate/physiology* ; Humans ; Lung ; Respiration

The study of mechanical properties on heart valves can provide an important theoretical basis for doctors to repair heart valves and prosthetic valve materials research. In this paper, we present the current status of the mechanical property study methods of heart valve, expound the methods and special requirements about uniaxial tensile test and biaxial tensile test of the heart valve, and further discuss several establishment methods of heart valve constitutive models. We also discuss the development trend of heart valve mechanics.
Heart Valve Prosthesis ; Heart Valves ; physiology ; Humans ; Prostheses and Implants

It is important to simulate the excitation propagation process of cardiac bio-electricity in the research of ECG forward problem. Traditional methods describe them with wave simulation algorithm such as LFX simulation algorithm and vector propagation algorithm etc, these methods have some problems to certain extent, due to the presence of discreteness of space and time and asymmetry of the myocardium. This paper discussed the simulation algorithm in 2-dimension space under the circumstance of layered and non-layered structure of myocardium. By calculating the theoretic values of simulating time based on Huygen's principle, we found that there were errors in LFX algorithm and no errors in vector propagation algorithm under the circumstance of non-layered structure of the myocardium, no mater what myocardium is isotropic or anisotropic. However, there exist errors from both algorithms when the myocardium has the layered structure. An improved algorithm is proposed and the simulations have been performed to examine the efficacy of the new algorithm, and the errors are reduced obviously. By increasing the number of myocardial blocks in the model, we also analyzed its influence on the error of simulation algorithm.
Algorithms ; Computer Simulation ; Heart ; physiology ; Models, Cardiovascular