Left ventricular function change was investigated in dogs during the postin-fusion period of experimental hemorrhagic shock. Hemodynamic parameters and the first derivative of left ventricular pressure (dp/dt) were recorded with an 4-channal polygraph and LVP-dp/dt loop was displayed on an attached oscilloscope simultaneously. In the study, LV function was assessed by + dp/dtmax, dp/dt/DP5.33, VCE at +dp/dtmax, Vmax, - dp/dtmax, - dp/dtmax/LVSP and VCE at -dp/dtmax. The results show that hemodynamic and LV function parameters approximate to the control levels 10 min after reinfusion. The performance then depresses significantly 60 min after renfusion and cardiac function deteriorates soon thereafter. The data are interpreted as direct evidence for a seriously-depressing myocardial performance during the early postin-fusion period of hemorrhagic shock in the dog.

The effects of the alterations of high altitude(at 4 000m for 48h and then at 5 000m for 24h)on the pulmonary rheography were investigated in 13 healthy male volunteers.It was found that the tonic interval index(Q-aI)was gradually prolonged jthe amplitude,the mean rate of filling and the maximal ascending rate of the systolic wave were gradually decreased.When the volunteers were exposed to 5 000m,the Q-aI/RVET was increased from the sea-level value to 0.319?.010 to 0.400?.016(P

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.

Dogs were bled and maintained at the mean arterial pressure(MAP)of 6.67 kPa(moderate shock)or of 5.33 kPa(severe shock)for 2 hours.Then the blood shed was transfused back to the animals and observation on the dogs was carried on for 2 more hours.26 mongrel dogs,weighing 10~16 kg,were randomized into Group I of normoxia and moderate shock(NMS,n=7),Group I of normoxia and severe shock(NSS,n=7).Group I of hypoxia at a simulated alti- tude of 4 000 m and moderate shock(HMS,n=6),and Group IV of hypoxia and severe shock(HSS,n=6).The changes of the cardiovascular function and the oxygen transport were observed in these animals after anesthetization.It was found that the cardiovascular function was similar in HMS and NMS groups.The decrease of VO2 of HMS animals was similar to that of NSS dogs.Decompensation occurred earlier in HSS animals and resulted in high mortality.

Objective Amiodarone was diluted to release the side effect of hypotension in clinic, but this maybe unsuitable during cardiopulmonary resuscitation (CPR). This study was designed to observe the effects of undiluted amiodarone, diluted amiodarone, and CPR alone on ventricular fibrillation (VF) in a pig model. MethodsVF was induced in 21 pigs. The animals were randomly (random mumber) divided into 3 groups after VF 3 min.① CPR group ( n= 7): standard CPR; ② undiluted amiodarone group ( n= 7): undiluted amiodarone (5 mg/kg)bolus within 3 s, then 20 mL saline flush into the peripheral vein, CPR was started after observed 30 s; ③ diluted amiodarone group ( n = 7): amiodarone was dissolved in 20 mL saline and bolus with 30 s. Defibrillation was attempted at VF 5 min. Results The restoration of spontaneous circulation (ROSC) of CPR and undiluted amiodarone groups were higher than diluted group (85.7％ vs. 71.4％ vs. 42.9％), but the differences were not significant (all P ＞0.05). The defibrillation energy and timesof CPR group were higher than that of undiluted amiodarone (P= 0.009) and diluted group ( P = 0. 170). The mean arterial pressure of undiluted amiodarone were lower than diluted and CPR groups at ROSC 10 min (all P ＜0.05), but the differences of undiluted and diluted groups were not significant after ROSC 0.5 h. Conclusions In this study, undiluted amiodaronecan effectively reduced the defibrillation times and energy. Although diluted amiodaronecan release the side effect of hypotension which was transient, it didn't significantly improved cardiac electric activity and delayed to start CPR.

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.

AIM:To explore the effect of atorvastatin on the function of carotid artery after adventitia removal in SHR.METHODS:16-week old male SHR(n=36) with left carotid artery adventitia removed were randomly divided into 3 groups(n=12,each):SHR control group,atorvastatin group,valsartan group and the half rats of each group were put to death at the 4th and 8th weeks respectively.The systolic blood pressure(SBP) was assessed before and after treatment with atorvastatin every 2 weeks.The velocity of carotid artery was detected by electromagnetic rheometer while vasotension changes to NE was measured using a force transducer connected with a polygraph.RESULTS:Compared with SHR control group,the SBP of atorvastatin group began declining at the 4th week,and was reduced significantly at the 6th and 8th weeks(P0.05).Vasotension to NE of carotid artery was reduced significantly after adventitia removal(P

Objective Gasp was defined as a pathology respiration during cardiac arrest. This study was to investigate its effect on hemodynamics during CPR. Method Twelve domestic pigs, weighening (30 ± 1) kg,were anaesthetized. After tracheal intubation and mechanical ventilation, continuous respiratory variables were recorded. An artery catheter was inserted for reference blood samples and measuring aortic artery pressure (AOP).Right atrial pressure (RAP) and cardiac output (CO) were detected by Swan-Ganz catheter. Ventricular fibrillation (VF) was induced by programmed electrical stimulation instruments. After 4 minutes untreated VF, standard 30:2 CPR was done for 12 minutes and the parameters were recorded. Results pH, PaCO2 and lactic acid increased and PaO2 decreased progressively during CPR, whereas PaO2 was up to 50mmHg during the whole protocol. Gasps were observed in 10 animals, but weaken gradually; the left 2 animals with no gasp did not restore of spontaneous circulation (ROSC). Standard CPR could produce passive ventilation more than dead space (VD), but its tidal volume decreased gradually, which led to the percentage of rescue ventilation increased progressively. Positive correlations were found between CO, coronary perfusion pressure (CPP) and minute ventilation of gasps (MVg) (r was 0.736 and 0.721 respectively, both P ＜0.01); negative correlation were found between RAP and MVg (r= -0. 744, P ＜ 0.01). Conclusions Standard CPR could maintain 12 minutes oxygenation of body; compressions could produce enough passive ventilation more than VD; gasps were benefit to ROSC by increasing CO, CPP and decreasing RAP.

Objective To reveal the changes of catecholamine and lactate levels in myocardial interstitial fluid during cardiopulmonary resuscitation in order to prove the protective effects of sildenafil pretreatment on post-resuscitation myocardial function in swine model of ventricular fibrillation (VF).Methods Twenty-four swine were randomly (random number) divided into three groups:saline group,sildenafil group and shame operation group.Sildenafil in dose of 0.5 mg/kg dissolved in 40 mL of saline was given to swine once intraperitoneally 40 min prior to VF in sildenafil group.The equivalent volume of saline (0.9％ NaC1) alone was administered instead in saline groups.There was no treatment in shame operation group.After ventricular fibrillation untreated for 8 min,open-chest cardiopulmonary resuscitation was initiated.The hemodynamic variables were recorded at baseline,4 min,1 h and 6 h after restoration of spontaneous circulation (ROSC).The interstitial fluid from the left ventricle wall was collected by using the microdialysis tubes at given intervals,in which the levels of dopamine,norepinephrine,epinephrine,and lactate were measured.The samples for pathological examination were taken at 24 hours after ROSC.Results The levels of catecholamine and lactate in the sildenafil group were lower than those in saline group at all different intervals (P ＜ 0.05 or P ＜ 0.01).The cumulative defibrillation energy was lower in the sildenafil group than that in the saline group (P ＜ 0.05).The hemodynamic changes and myocardial histological damage in sildenafil group were milder than those in saline group (P ＜ 0.05).The pathologic changes of myocardium and mitochondria in saline group were more severe than those in sildenafil group.Conclusions Sildenafil pretreatment prior to VF can effectively reduce endogenous catecholamine secretion and lactate levels in myocardial tissue,protecting the myocardium and improving post-resuscitation myocardial function.