Effects of Lead on Systolic and Diastolic Cardiac Functions

In this paper, both systolic and diastolic cardiac functions were cvaluatcd in 54 lead exposed and 24 non-exposed workers by Doppler cchocardiography. With regard to systolic cardiac function, the results suggested that cardiac systolic function increased in exposed groups as a compensatory response for the effecl of lead on myocardium. To study left ventriculaf diastolic function, 2.5 MHz pulsed Doppler analyses of transmitral flow velocity were performed from apical four-chamber view. The results showed that timerelated parameters were comparable among all groups, but blood flow velocity through the mitral valve and Doppler area fractions changed significantly in lead-exposed groups as cvidenced by increased value A, decreased value E and E/A ratio. The decrease of diastolic cardiac function was more significant in lead intoxication group. It was also observed in this study that the activity in serum of thc MB isoenzyme of creatine phosphokinase (CPK-MB), one of the indices of myocardial damage, was significantly highcr in exposed group than that in control (P (0.05), and a positive correlation was found between CPK-MB activity and Pb-B. It denoted that the inereasing of lead burden leads to more release of CPK-MB from the myocardial cells and suggested the existence of slight myocardial damage, which, conceivably, might cause harm to diastolic cardiac function

EFFECT OF ELECTROACUPUNCTURE OF THE HEART MERIDIAN ACUPOINTS ON ISCHEMIC CARDIAC FUNCTION IN THE RABBIT

Subjective: To observe the effect of electroacupuncture (EA) of acupoints of the Heart Meridian and Lung Meridian on ischemic cardiac systolic ability for analyzing the relative specific relationship between the Heart Meridian and the heart. Methods: Acute myocardial ischemia (AMI) was produced by intravenous infusion of pituitrin (40 u + 5% glucose injection 500 ml, 60 drips/min) in the rabbit. Left intraventricular pressure (LVP), maximal rising velocity of LVP (dp/dt max), isovolumetric pressure (IP) and end-diastolic pressure (EDP) of the left cardiac ventricle were used as the indexes. Three points of Heart Meridian [HM, from 'Shenmen' (HT 7) to 'Lingdao' (HT 4)] and the three points of Lung Meridian [LM, from 'Taiyuan' (LU 9) to 'Lieque' (LU 7)] were punctured with filiform needles and stimulated with hand-manipulation and electrically with ZY2-1 EA Therapeutic Apparatus. 30 rabbits anesthetized with urethane (1 g/kg) were randomly and evenly divided into control group, HM group and LM group. Result-s: The effects of EA of HM points were evidently superior to those of EA of LM points in promoting the recovery of both AMI-induced decrease of LVP and dp/dtmax, and AMI-induced increase of IP and EDP. Conclusion: Acupoints of Heart Meridian has a relatively specific connection with the heart in comparison with those of Lung Meridian; and the Heart Meridian is a functional whole.

Effect of Systolic Cardiac Function on Passive Leg Raising for Predicting Fluid Responsiveness： A Prospective Observational Study

Background：Passive leg raising （PLR） represents a ＂self-volume expansion （VE）＂ that could predict fluid responsiveness,but the influence of systolic cardiac function on PLR has seldom been reported.This study aimed to investigate whether systolic cardiac function,estimated by the global ejection fraction （GEF） from transpulmonary-thermodilution,could influence the diagnostic value of PLR.Methods：This prospective,observational study was carried out in the surgical Intensive Care Unit of the First Affiliated Hospital of Sun Yat-sen University from December 2013 to July 2015.Seventy-eight mechanically ventilated patients considered for VE were prospectively included and divided into a low-GEF （〈20%） and a near-normal-GEF （〉20%） group.Within each group,baseline hemodynamics,after PLR and after VE （250 ml 5% albumin over 30 min）,were recorded.PLR-induced hemodynamic changes （PLR-△） were calculated.Fluid responders were defined by a 15% increase of stroke volume （SV） after VE.Results：Twenty-five out of 38 patients were responders in the GEF 〈20% group,compared to 26 out of 40 patients in the GEF 〉20% group.The thresholds of PLR-△SV and PLR-△ cardiac output （PLR-△CO） for predicting fluid responsiveness were higher in the GEF 〉20% group than in the GEF 〈20% group （△SV：12% vs.8%;△CO：7% vs.6%）,with increased sensitivity （△SV：92% vs.92%;△CO：81% vs.80%） and specificity （△SV：86% vs.70%;△CO：86% vs.77%）,respectively PLR-△ heart rate could predict fluid responsiveness in the GEF 〉20% group with a threshold value of-5% （sensitivity 65%,specificity 93%） but could not in the GEF 〈20% group.The pressure index changes were poor predictors.Conclusions：In the critically ill patients on mechanical ventilation,the diagnostic value of PLR for predicting fluid responsiveness depends on cardiac systolic function.Thus,cardiac systolic function must be considered when using PLR.Trial Registration：Chinese Clinical Trial Register,ChiCTR-OCH-13004027;http：//www.chictr.org.cn/showproj.aspx？proj=5540.

Multiple hemodynamic effects of endogenous hydrogen sulfide on central nervous system in rats

Background Endogenous hydrogen sulfide is a new neuromodulator which takes part in the regulation of central nervous system physiology and diseases. Whether endogenous hydrogen sulfide in the central nervous system regulates cardiovascular activity is not known. In the present study, we observed the hemodynamic changes of hydrogen sulfide or its precursor by intracerebroventricular injection, and investigate the possible roles of endogenous digitalis like factors and sympathetic activity in the regulation. Methods Ninety-four Sprague-Dawley rats underwent a right cerebroventricular puncture, then the hydrogen sulfide saturation buffer or its precursor injected by intrcerebroventricular catheter. A heperin-filled catheter was inserted into the right femoral artery or into the left ventricle, and changes of blood pressure or cardiac function recorded by a Powerlab/4S instrument. Phentolamine or metoprolol were pre-injected to observe the possible role in autonomic nerve activity. After rats were sacrificed, plasma was collected and endogenous digitalis-like factors were measured with a commercial radioimmunoassay kit. The aortic, cardiac sarcolemmal vesicles were isolated and the activity of Na＋-K＋-ATPase was measured as ouabain-sensitive ATP hydrolysis under maximal velocity conditions by measuring the release of inorganic phosphate from ATP. Unpaired Student＇s ttest for two groups or analysis of variances （ANOVA） for multiple groups were used to compare the differences of the changes. Results Intracerebroventricular injection of hydrogen sulfide induced a transient hypotension, then dramatic hypertenive effects in a dose-dependent manner. Bolus injection of L-cysteine or beta-mercaptopyruvate also increased mean arterial pressure （P 〈0.01）, whereas hydroxylamine-a cystathionine beta synthase inhibitor decreased the arterial pressure （P 〈0.01）. Hydrogen sulfide and L-cysteine increased mean arterial pressure, left ventricular develop pressure and left-ventricle maximal rate of systolic and diastolic pressure; these functions were decreased by hydroxylamine （P 〈0.01）. Glibenclamide （a KATP channel blocker） blocked the transient hypotensive effect, phentolamine （an alpha-adrenergic receptor blocker） blocked the hypertensive effect, and metoprolol （a selective beta 1 receptor blocker） blocked the positive inoptropic effect of central nervous system hydrogen sulfide. The endogenous digitalis-like factors in plasma were elevated （P 〈0.01） after treatment with L-cysteine, association with decreasing Na＋-K＋-ATPase activity in cardiac or aortic sarcolemmal vesicles （P 〈0.01）. Hydroxylamine injection reduced the endogenous digitalis-like factors level in plasma association with increasing Na＋-K＋-ATPase activity in cardiac and aortic sarcolemmal vesicles. Conclusion Central nervous system endogenous hydrogen sulfide upregulated mean arterial pressure and cardiac systolic function by activation of sympathetic nerves or release of endogenous digitalis-like factors.