The combined effect of stepwise intermittent hypoxia and physical training was investigated with ultrasonic cardiography on 12 bikers who were permanent inhabitants at 1895 meters above sea level and were subjecting to physical training under hypoxic condition in a hypobaric chamber. It was found that the internal diameters of the right ventricle and right pulmonary artery of the bikers increased proportionally with the increase of both the altitude and the duration of the physical training. At a simulated altitude of 4000 meters, the cardiac stroke volume and cardiac cutput, the internal diameter of the left ventricle and the left ventricular mass increased markedly as compared with those at sea level. The thickness of the interventricular septum and the posterior wall of the left ventricle also increased. The stroke volume and cardiac output of the bikers increased more significantly at the simulated altitude of 4000m., that at the altitude of 3000m. All these change are still within the physiologic ranges and can be considered as adaptation changes to highaltitude training. NO case of acute mountain sickness occurred in any of the trained bikers.These findings suggest that this intermittent stepwise hypoxic physical training can improve the cardiac function and increase its adaptibility towards hypo-xic conditions.

The changes of pulmonary rheography of 12 bikers were investigated after they had been physically trained under hypoxic condition in a hypobaric chamber simulating altitudes of 2000 m, 3000m, and 4000m respectively. All the bikers were permanent inhabitants at 1895 meters above sea level.The changes were most marked on the rheographies taken at the simulated altitude of 4000m. Comparing with the control values at the sea level, the authors found that tonic interval (Q-a interval) on the bikers' pulmonary rheographies was prolonged. The amplitude, the mean rate of filling and the rate of maximal ascending of the systolic wave were decreased.The results showed that hypoxic physical training could result in the contraction of pulmonary vessels. In turn it caused pulmonary arterial hypertension and reduced the amount of blood circulating through the lungs. Pulmonary arterial hypertension could further increase the afterload of the right ventricle.Eight days after the bikers returned to the sea level, all the indices also returned to their original levels except the tonic interval. It is apparent that these changes are most likely to be functional rather than organic.

The dynamic changes of the functions and the weight index of the 2 ventricles and the density of ?-adrenoceptors in the myocardium were observed and the correlation between the changes of ?-adrenoceptors of the myocardium and.the peripheral lymphocytes was investigated during and after intermittent chronic hypbxia in rabbits.The fingings were as follows.(1)Chronic hypoxia resulted in an increase of systolic pressure,dp/dtmas and weight index of the right ventricle.25 days after the restoration of normal oxygen supply,systolic pressure and dp/dtomas of the right ventricle became normal but its weight index remained increased.(2)The density of ?-adrenoceptors of the 2 ventricles was reduced on the 7th,15th and 30th day of hypoxia as compared with that of the control.25 days after the restoration of oxygen supply,the density of ?-adrenoceptors became normal in the left ventricle but remained decreased in the right ventricle.(3)There was a positive correlation between the changes of ?-adrenoceptors in the 2 ventricles and peripheral lymphocytes.The findings suggest that hypoxia-induced hypertrophy of the right ventricle is usually accompanied with a decreased density of its ?-adrenoceptors and thedensity of ?-adrenoceptors of peripheral lymphocytes can reflect the changes of ?-adrenoceptors in the myocardium.

Objective:To investigate the characteristics of primary catheter malposition (PCM) following totally implantable venous access port (TIVAP) implantation via the internal jugular vein (IJV) and management strategies.Methods:Clinical data of 587 consecutive breast cancer patients undergoing TIVAP implantation via the IJV performed by single team at the Department of Breast Surgery, the First Affiliated Hospital of Zhengzhou University from Aug 2017 to Aug 2022 was retrospectively analyzed.Results:A total of 593 TIVAP were implanted and PCM was found in 18 cases (3.0%). Four hundred and twenty five TIVAP were implanted via the right IJV with one PCM case (0.2%). One hundred and sixty eight TIVAP implantations were performed via the left IJV and PCM occurred in 17 cases (10.1%). The interventional management with a pigtail catheter was performed as a first-line strategy in 11 of the 18 PCM cases, with a success in 10 cases and failure in one. Three cases were successfully managed with the digital subtraction angiography (DSA)-guided open approach. Four cases underwent blind open procedure firstly and 2 suffered a failure.Conclusions:A higher incidence of PCM is found in TIVAP implantations via the left IJV than the right one. The interventional management with a pigtail catheter or the DSA-guided open procedure proves to be feasible for the correction of PCM.