Reliability of Echocardiographic Pulmonary Vascular Resistance to Screen for the New Definition of Precapillary Pulmonary Hypertension in Uncorrected Secundum Atrial Septal Defect

Background and Objective:The most feared complication of uncorrected secundum Atrial Septal Defect(ASD)is pulmonary arterial hypertension(PAH).Pulmonary vascular resistance(PVR)is crucial in detecting precapil-lary pulmonary hypertension(PH)to guide the need for PAH-specific therapy.There is a change in the cut-off value of PVR according to the recently updated PH guideline.How echocardiographic PVR(PVRecho)correlates to PVR by right heart catheterization(RHC)(PVRcath)according to the new guidelines has not been known.The aim of this study is to determine the reliability of PVRecho in detecting PAH in Uncorrected Ostium Secundum ASD based on the current updated guideline and to help screen the high PVR group.Methods:429 ostium secun-dum ASD in the COngenital HeARt Disease in Adult and Pulmonary Hypertension(COHARD-PH)registry was divided into three groups according to the PVR.PVRecho was calculated using Abbas’Formula and compared the its gold standard,the PVRcath.The correlation between the two methods was analyzed.The Bland-Altman plot was used to analyze the agreement between the two methods.Receiver operating characteristics(ROC)analysis was used to determine the PVRecho cut-off value for high PVR.Results:The majority of the population(63.5%)had high PVR.Female gender dominated the study population(84%).PVR_(echo) was significantly correlated with PVRcath(r=0.6225,p<0.0001).Bland-Altman plot among all groups and in subgroups analysis showed a wide range of agreement.PVRecho underestimated PVRcath 5.124 WU.In subgroup analysis,PVRecho overestimated PVRcath 0.35 WU in those with PVR<2 WU.In the second and third groups,PVR_(echo) underestimated PVRcath 0.52 and 10.77 WU,respectively.Conclusion:PVRecho is reliable in predicting high PVR in uncorrected secun-dum ASD.However,there is a wide range of agreement.PVR_(echo) cut-off value of>1.62 WU showed good dis-criminatory power in determining high PVR.

Hemodynamic Profiling Using a Cardiac Index–Systemic Vascular Resistance Plot in Patients with Fontan Circulation

Background: Elevated Fontan pressure (FP) alone cannot fully predict clinical outcomes. We hypothesized thathemodynamic profiling using a cardiac index (CI)-systemic vascular resistance (SVR) plot could characterize clinicalfeatures and predict the prognosis of post-Fontan patients. Methods: We included post-Fontan patients whounderwent cardiac catheterization at age < 10 years. Patients were classified into four categories: A, CI ≥ 3, SVRindex (SVRI) ≥ 20;B, CI < 3, SVRI ≥ 20;C, CI ≥ 3, SVRI < 20;and D, CI < 3, SVRI < 20. The primary outcome wasfreedom from the combined endpoint: new onset of protein-losing enteropathy or plastic bronchitis, heart transplant,and death. Clinical and hemodynamic variables and freedom from the endpoint were compared betweenthe hemodynamic categories and outcome predictors were evaluated. Results: Eighty-three patients wereincluded. Median follow-up was 5.3 years. Category A/B/C/D consisted of 4/15/53/11 patients, respectively. Allthe patients in category A were New York Heart Association I/II and had a significantly lower pulmonary vascularresistance index (PVRI). Patients in category C had lower pulmonary/systemic blood flow. Patients in category Dhad a higher PVRI and had the poorest freedom from the endpoint (44% at 5 years). Elevated FP and category Dwere outcome predictors. Conclusions: CI-SVR plots was a novel adjunctive method for Fontan hemodynamicprofiling.

Cardiovascular Function during First 24 Hours after Off-Pump and On-Pump CABG—A Prospective Observational Comparative Study

Purpose: Myocardial revascularization by coronary artery bypass grafting (CABG) in ischemic heart disease patients has direct impact on hemodynamic parameters in the immediate post-operative period. The peri-operative cardiovascular functioning is an important determinant for outcome of surgery. In On-Pump CABG (ONCAB), the cardiopulmonary bypass has a negative effect on myocardium. Off-Pump CABG (OPCAB) avoids the effect of CPB but complete revascularization with difficult positioning of heart is technically demanding. This study is aimed to compare the cardiovascular functioning in the immediate post-operative period after OPCAB and ONCAB. Methods: Total 106 patients were operated for CABG from January 2015 to June 2016, of which 75 patients were operated for OPCAB and 31 patients were operated for ONCAB. For the comparison, hemodynamic parameters were measured during anesthesia before surgery, postoperatively after 1 and 4 hours (h) in the ICU, and in the morning after surgery, approximately after 20 h. Results: The time-dependent rise of hemodynamic parameters like Cardiac Output (CO), Cardiac Index (CI), Stroke volume (SV) and Left Ventricular Stroke Work Index (LVSWI) in the immediate post-operative hours (1 h and 4 h) are more predominant in OPCAB group than ONCAB group although the difference is eliminated mostly at 20 h. The better peripheral vasodilation after OPCAB causes immediate fall of Systemic Vascular Resistance Index (SVRI) after OPCAB. Conclusion: Better cardiovascular functioning immediately after OPCAB than ONCAB may be important for better hemodynamic stability. The difference is however eliminated after 24 hours indicating little significance in long term outcome.

Effect of remimazolam vs. propofol on hemodynamics during general anesthesia induction in elderly patients: Single-center, randomized controlled trial

The current study aimed to compare the effects between remimazolam and propofol on hemodynamic stability during the induction of general anesthesia in elderly patients.We used propofol at a rate of 60 mg/(kg·h)in the propofol group(group P)or remimazolam at a rate of 6 mg/(kg·h)in the remimazolam group(group R)for the induction.A processed electroencephalogram was used to determine whether the induction was successful and when to stop the infusion of the study drug.We measured when patients entered the operating room(T_(0)),when the induction was successful(T_(1)),and when before(T_(2))and 5 min after successful endotracheal intubation(T_(3)).We found that mean arterial pressure(MAP)was lower at T_(1–3),compared with T_(0) in both groups,but higher at T_(2) in the group R,whileΔMAP_(T0–T2) andΔMAP_(max) were smaller in the group R(ΔMAP_(T0–T2):the difference between MAP at time point T_(0) and T_(2),ΔMAP_(max):the difference between MAP at time point T_(0) and the lowest value from T_(0) to T_(3)).Cardiac index and stroke volume index did not differ between groups,whereas systemic vascular resistance index was higher at T_(1–3) in the group R.These findings show that remimazolam,compared with propofol,better maintains hemodynamic stability during the induction,which may be attributed to its ability to better maintain systemic vascular resistance levels.

Development of pulmonary hypertension remains a major hurdle to corrective surgery in Down syndrome

Down syndrome is the most common chromosomal abnormality encountered in clinical practice with 50%of them having associated congenital heart disease(CHD).Shunt lesions account for around 75%of all CHDs in Down syndrome.Down syndrome patients,especially with large shunts are particularly predisposed to early development of severe pulmonary hypertension(PH)compared with shunt lesions in general population.This necessitates timely surgical correction which remains the only viable option to prevent long term morbidity and mortality.However,despite clear recommendations,there is wide gap between actual practice and fear of underlying PH which often leads to surgical refusals in Down syndrome even when the shunt is reversible.Another peculiarity is that Down syndrome patients can develop PH even after successful correction of shunt.It is not uncommon to come across Down syndrome patients with uncorrected shunts in adulthood with irreversible PH at which stage intracardiac repair is contraindicated and the only option available is a combined heartlung transplant.However,despite the guidelines laid by authorities,the rates of cardiac transplant in adult Down syndrome remain dismal largely attributable to the high prevalence of intellectual disability in them.The index case presents a real-world scenario highlighting the impact of severe PH on treatment strategies and discrimination driven by the fear of worse outcomes in these patients.

Intraoperative systemic vascular resistance is associated with postoperative nausea and vomiting after laparoscopic hysterectomy

BACKGROUND The incidence of postoperative nausea and vomiting(PONV)in patients undergoing laparoscopic hysterectomy is very high compared with other surgeries,even when many prophylactic measures have been taken.However,the pathogenesis of PONV is multifactorial.Female sex,a history of motion sickness or PONV,nonsmokers,and perioperative opioid use are the most closely related factors.Among the multiple risk factors,suboptimal gastrointestinal(GI)perfusion may be attributed to some cases of PONV,and increased systemic vascular resistance(SVR)may lead to GI ischemia.The hypothesis of this research was that SVR is related to PONV.AIM To investigate the relationship between SVR and PONV in patients undergoing laparoscopic hysterectomy.METHODS A total of 228 patients who underwent elective laparoscopic hysterectomy were included in this prospective observational study.SVR was monitored using a noninvasive hemodynamic monitoring system.Four indices of SVR,the baseline,mean,area under the curve(AUC),and weighted AUC,were used for analysis.The incidence and severity of nausea and vomiting were evaluated while patients were awake and throughout the intervals from 0 to 2 h,2 to 6 h,and 6 to 24 h starting upon arrival at the post-anesthesia care unit.The associations between various SVR indices and PONV were investigated by logistic regression.P<0.05 was considered statistically significant.RESULTS The incidence of PONV in the study was 56.14%(128/228),and PONV tended to appear within 6 h after surgery.Five variables were significant in univariate analyses,however,only SVR mean[odds ratio(OR)=1.015,95%CI:1.005-1.109,P=0.047]and duration of surgery(OR=1.316,95%CI:1.003-2.030,P=0.012)were associated with PONV after logistic regression analysis.Furthermore,patients with high SVR mean were more likely to suffer from PONV after laparoscopic hysterectomy.On average,patients who developed PONV needed more time to tolerate diet and demonstrated poorer sleep quality on the first night after surgery.CONCLUSION In this study,PONV was a common complication after laparoscopic hysterectomy.SVR was associated with PONV,and high SVR mean was associated with a significantly increased risk of PONV.

Cirrhotic portal hypertension: From pathophysiology to novel therapeutics

Portal hypertension and bleeding from gastroesophageal varices is the major cause of morbidity and mortality in patients with cirrhosis. Portal hypertension is initiated by increased intrahepatic vascular resistance and a hyperdynamic circulatory state. The latter is characterized by a high cardiac output, increased total blood volume and splanchnic vasodilatation, resulting in increased mesenteric blood flow. Pharmacological manipulation of cirrhotic portal hypertension targets both the splanchnic and hepatic vascular beds. Drugs such as angiotensin converting enzyme inhibitors and angiotensin Ⅱ type receptor 1 blockers, which target the components of the classical renin angiotensin system(RAS), are expected to reduce intrahepatic vascular tone by reducing extracellular matrix deposition and vasoactivity of contractile cells and thereby improve portal hypertension. However, these drugs have been shown to produce significant offtarget effects such as systemic hypotension and renal failure. Therefore, the current pharmacological mainstay in clinical practice to prevent variceal bleeding and improving patient survival by reducing portal pressure is non-selective-blockers(NSBBs). These NSBBs work by reducing cardiac output and splanchnic vasodilatation but most patients do not achieve an optimal therapeutic response and a significant proportion of patients are unable to tolerate these drugs.Although statins, used alone or in combination with NSBBs, have been shown to improve portal pressure and overall mortality in cirrhotic patients, further randomized clinical trials are warranted involving larger patient populations with clear clinical end points. On the other hand, recent findings from studies that have investigated the potential use of the blockers of the components of the alternate RAS provided compelling evidence that could lead to the development of drugs targeting the splanchnic vascular bed to inhibit splanchnic vasodilatation in portal hypertension. This review outlines the mechanisms related to the pathogenesis of portal hypertension and attempts to provide an update on currently available therapeutic approaches in the management of portal hypertension with special emphasis on how the alternate RAS could be manipulated in our search for development of safe, specific and effective novel therapies to treat portal hypertension in cirrhosis.

Gut-liver axis in cirrhosis:Are hemodynamic changes a missing link?

Recent evidence suggests that the condition of the gut and its microbiota greatly influence the course of liver disease,especially cirrhosis.This introduces the concept of the gut-liver axis,which can be imagined as a chain connected by several links.Gut dysbiosis,small intestinal bacterial overgrowth,and intestinal barrier alteration lead to bacterial translocation,resulting in systemic inflammation.Systemic inflammation further causes vasodilation,arterial hypotension,and hyperdynamic circulation,leading to the aggravation of portal hypertension,which contributes to the development of complications of cirrhosis,resulting in a poorer prognosis.The majority of the data underlying this model were obtained initially from animal experiments,and most of these correlations were further reproduced in studies including patients with cirrhosis.However,despite the published data on the relationship of the disorders of the gut microbiota with the complications of cirrhosis and the proposed pathogenetic role of hemodynamic disorders in their development,the direct relations between gut dysbiosis and hemodynamic changes in this disease are poorly studied.They remain a missing link in the gut-liver axis and a challenge for future research.

Efficacy of Bosentan in Patients after Fontan Procedures：a Double-blind, Randomized Controlled Trial

Fontan surgery is a widely used palliative procedure that significantly improves the survival period of patients with complex congenital heart disease（CHD）. However, it does not decrease postoperative complication rate. Previous studies suggested that elevated mean pulmonary artery pressure（m PAP） and vascular resistance lead to decreased exercise tolerance and myocardial dysfunction. Therapy with endothelial receptor antagonists（Bosentan） has been demonstrated to improve the patients＇ prognosis. A double-blind, randomized controlled trial was performed to explore the efficacy of Bosentan in treating patients who underwent the Fontan procedure. Eligible participants were randomly divided into Bosentan group and control group. Liver function was tested at a local hospital and the results were reported to the phone inspector every month. If the results suggested abnormal liver function, treatment would be adjusted or terminated. All the participants finished the follow-up study, with no patients lost to follow-up. Unblinding after 2-year follow-up, no mortality was observed in either group. However, secondary end-points were found to be significantly different in the comparable groups. The cardiac function and 6-min walking distance in the Bosentan group were significantly superior to those in the control group（P=0.018 and P=0.027）. Bosentan could improve New York Heart Association（NYHA） functional status and improve the results of the 6-min walking test（6MWT） in Fontan patients post-surgery, and no other benefits were observed. Furthermore, a primary meta-analysis study systematically reviewed all the similar clinical trails worldwide and concluded an overall NYHA class improvement in Fontan patients who received Bosentan treatments.

Differences in Heart Stroke Volume between Han and Korean-Chinese Nationalities and Correlative Factors

Objective To compare the differences in stroke volume （SV） and stroke volume index （Sl） between Han and Korean-Chinese and to investigate the correlated risk factors. Methods A total of 1 647 Han and 876 Korean-Chinese aged 10-80 years were investigated. SV, SI, cardiac output, cardiac output index, heart rate （HR）, systemic vascular resistance （SVR）, systemic vascular resistance index （SVRI）, and blood pressure were measured. Results SV/SI values in Korean-Chinese were lower than those in the Han of the same sex and age. Covariance analysis showed that, apart from the effect of sex, age and body mass index （BMI）, the differences in SV and SI between the two cohorts were still significant （P〈O.O01）. Multiple regression analysis revealed that the SV difference between the two ethnicities was affected （in descending order from a strong to weak correlation） by SVR, SVRI, HR, diastolic blood pressure, mean arterial pressure, BMI, and systolic blood pressure, while the SI difference was affected by SVR, SVRI, HR, mean arterial pressure, diastolic and systolic blood pressure, and BMI. Conclusion The Fact that SV and SI in Korean-Chinese are lower than those in Han is related with higher SVR, HR and blood pressure in the Korean-Chinese.

Prognostic value of hemodynamic indices in patients with sepsis after fluid resuscitation

BACKGROUND Sepsis usually causes hemodynamic abnormalities.Hemodynamic index is one of the factors to identify the severity of sepsis and an important parameter to guide the procedure of fluid resuscitation.The present study investigated whether the assessment of hemodynamic indices can predict the outcomes of septic patients undergoing resuscitation therapy.AIM To evaluate the prognostic value of hemodynamic indices in patients with sepsis after fluid resuscitation.METHODS A retrospective study was conducted in 120 patients with sepsis at Hainan General Hospital/Hainan Affiliated Hospital of Hainan Medical University between October 2016 and October 2019.All patients were treated with sodium chloride combined with dextran glucose injection for fluid resuscitation.Patients’hemodynamic parameters were monitored,including heart rate(HR),cardiac index(CI),systemic vascular resistance index(SVRI),mean arterial pressure(MAP),central venous pressure(CVP),and central venous oxygen saturation.The prognostic value of hemodynamic indices was determined based on the prognosis status.RESULTS During fluid resuscitation,86 patients developed septic shock and 34 did not.Ninety-nine patients survived and 21 patients died at 28 d after the treatment.Heart rate,CI,mean arterial pressure,SVRI,and CVP were higher in patients with septic shock and patients who died from septic shock than in non-shock patients and patients who survived,and central venous oxygen saturation was lower in patients with shock and patients who died than in non-shock patients and thesurvivors (P < 0.05). When prognosis was considered as a dependent variable andhemodynamic parameters was considered as independent variables, the results ofa logistic regression analysis showed that CI, SVRI, and CVP were independentrisk factors for septic shock, and CI was an independent risk factor for 28-dmortality (P < 0.05).CONCLUSIONHemodynamic indices can be used to evaluate the prognosis of septic patientsafter fluid resuscitation.

Effects of Nitroglycerine on Erythrocyte Rheology:A Novel Mechanism to Explain the Enhancement of Nutrient Blood Flow to Ischemic Zones

Objectives Nitroglycerine (NTG) enhances coronary blood flow to compromised myocardium is important in relieving ischemia. However, the mechanism for this increase in myocardial blood flow (MBF) is not well defined. In small vessels and capillaries, relative blood viscosity plays a very important role in determining myocardial vascular resistance (MVR). MVR reduce is due partly to the increase in negative charge of erythrocyte surface. We therefore hypothesized that the enhancement of nutrient blood flow to zones of myocardial ischemia during NTG is partly secondary to reduced MVR and blood flow viscosity. The latter is affected by the negative charge of erythrocyte surface. Methods 6 dogs with LAD flow-limiting stenosis (group 1) and 6 dogs with LAD flow-limiting stenosis and LCx occmusion (group 2) were studied. At baseline and during intracoronary infusions of NTG (0.3-0.6 μg·kg-1·min-1), hemodynamics, MBF (mL·min-1·g-1), whole blood viscosity (WBη, mPa. S), elongation index (EI), eletrophoretic mobility of erythocytes (EME, [μ.s-1)/(V.cm-1)]) and percent wall thickening (%WT) were determined. MVR was calculated using driving pressure/MBF. Results As compared to baseline, no changes in hemodynamics were seen during NTG. MBF increased and MVR decreased significantly in normal bed, the central 25% and the entire of stenosed bed (P<0.05), with a decrease in WBη in both group 1 and group 2 dogs (18.6±9.7 % and 19.2±14.5 %, respectively). However, the % decrease in WBη was proportioned to the % increase in MBF or the % decrease in MVR only in the central 25% of stenosed bed (r=0.87, P<0.001), but not in the entire stenosed bed and normal bed. EI did not show statistically significant differences between during NTG and at baseline, but EME did increase. And the % decrease in WBη during NTG was related to the % increase in EME (r=0.83, P=0.01). Conclusions NTG reduced myocardial vascular resistance and blood viscosity due to the change of negative charge of erythrocyte surface may, in part, be the mechanism of the enhancement of nutrient blood flow to zones of myocardial ischemia. These results provide additional insights into the complex anti-ischemic effects of NTG.

The warfare for plant highway:vascular plant–microbe interaction pinpoints lignin

Plant vascular pathogens are one kind of destructive pathogens in agricultural production.However,mechanisms behind the vascular pathogen-recognition and the subsequent defense responses of plants are not well known.A recent pioneering study on plant vascular immunity discovered a conserved MKP1-MPK-MYB signaling cascade that activates lignin biosynthesis in vascular tissues to confer vascular resistance in both monocot rice and the dicot Arabidopsis.The breakthrough provides a novel view on plant immunity to vascular pathogens and offers a potential strategy for the future breeding of disease-resistant crops.

Portal Hypertension in Nonalcoholic Fatty Liver Disease: Challenges and Paradigms

Portal hypertension in cirrhosis is defined as an increase in the portal pressure gradient(PPG)between the portal and hepatic veins and is traditionally estimated by the hepatic venous pressure gradient(HVPG),which is the difference in pressure between the free-floating and wedged positions of a balloon catheter in the hepatic vein.By convention,􀀫HVPG≥10mmHg indicates clinically significant portal hypertension,which is associated with adverse clinical outcomes.Nonalcoholic fatty liver disease(NAFLD)is a common disorder with a heterogeneous clinical course,which includes the development of portal hypertension.There is increasing evidence that portal hypertension in NAFLD deserves special considerations.First,elevated PPG often precedes fibrosis in NAFLD,suggesting a bidirectional relationship between these pathological processes.Second,HVPG underestimates PPG in NAFLD,suggesting that portal hypertension is more prevalent in this condition than currently believed.Third,cellular mechanoresponses generated early in the pathogenesis of NAFLD provide a mechanistic explanation for the pressurefibrosis paradigm.Finally,a better understanding of liver mechanobiology in NAFLD may aid in the development of novel pharmaceutical targets for prevention and management of this disease.

Echocardiogram in predicting correctable shunts in ventricular septal defect patients associated with severe pulmonary hypertension

Background Echocardiogram is a simple and useful tool in disease assessment.In ventricular septal defect(VSD)patients with severe pulmonary hypertension(PH),it is difficult to judge whether further intervention is needed.Therefore,this study aimed to investigate the application of echocardiogram in predicting the severity of pulmonary hypertension and guide subsequent management.Methods This study included VSD patients who underwent right heart catheterization(RHC)examination in Guangdong Provincial People's Hospital from January2011 to December 2022.An estimated pulmonary artery systolic pressure(e PASP)higher than 60 mm Hg was defined as severe PH in this study.Logistic regression analysis and receiver operating characteristic curve(ROC)analysis were used.Results A total of 186 VSD patients with severe PH(e PASP more than 60 mm Hg)were included in this study,with 158 cases in the non-correctable group and 28 cases in the collectable group.In univariable logistic regression,left atrium dimension(LA),left ventricular end-diastolic dimension(LVDd),left ventricular end-systolic dimension(LVDs),peak velocity of the pulmonary valve(PV),peak velocities from the early phase of the mitral inflow(MVE),bidirectional shunting and pericardial effusion were associated with a correctable shunt.When adjusted in multivariable model,only PV and bidirectional shunting remained statistically significant.The ROC curve found that PV exhibits good discriminative ability for correctable shunt(AUC[area under the curve]:0.779,95%CI:0.676-0.871)with a cut-off value of 1.465 m/s.The predictive performance of bidirectional shunting was not satisfactory,with a low AUC of 0.669(95%CI:0.571-0.766).Conclusions PV and bidirectional shunting are simple and clinically available parameters from echocardiogram in predicting PH severity,which not only avoids the repeated unnecessary cardiac catheterization,but also provides a reference basis for follow-up evaluation.

Plasma Neuropeptide Y Levels in Vasovagal Syncope in Children

Background： Vasovagal syncope （VVS） is the most common cause of syncope in children. Neuropeptide Y （NPY） plays an important role in the regulation of blood pressure （BP）, as well as myocardial contractility. This study aimed to explore the role of plasma NPY in VVS in children. Methods： Fifty-six children who were diagnosed with VVS （VVS group） using head-up tilt test （HUT） and 31 healthy children who were selected as controls （control group） were enrolled. Plasma NPY concentrations were detected. The independent t-test was used to compare the data of the VVS group with those of the control group. The changes in plasma NPY levels in the VVS group during the HUT, as well as hemodynamic parameters, such as heart rate （HR）, BP, total peripheral vascular resistance （TPVR）, and cardiac output （CO）, were evaluated using the paired t-test. Furthermore, the correlations between plasma NPY levels and hemodynamic parameters were analyzed using bivariate correlation analysis. Results： The BP, HR, and plasma NPY （0.34 ± 0.12 pg/ml vs. 0.46 ± 0.13 pg/ml） levels in the supine position were statistically low in the VVS group compared to levels in the control group （all P 〈 0.05）. Plasma NPY levels were positively correlated with the HR （Pearson, R = 0.395, P 〈 0.001） and diastolic BP （Pearson, R = 0.311, P = 0.003） when patients were in the supine position. When patients in the VVS group were in the supine position, elevated TPVR （4.6 ± 3.7 mmHg·min-1·L-1 vs. 2.5 ± 1.0 mmHg·min-1·L-1, respectively, P 〈 0.001;1 mmHg = 0.133 kPa） and reduced CO （1.0 ± 0.7 L/min vs. 2.4 ± 1.3 L/min, respectively, P 〈 0.001） were observed in the positive-response period compared with baseline values. The plasma NPY levels were positively correlated with TPVR （Spearman, R = 0.294, P = 0.028） but negatively correlated with CO in the positive-response period during HUT （Spearman, R = -0.318, P = 0.017）. Conclusions： Plasma NPY may contribute to the pathogenesis of VVS by increasing the TPVR and decreasing the CO during orthostatic regulation.

Postnatal hemodynamic changes in low-birth-weight and very-low-birth-weight infants during the first 72 h of life

Background Despite increasing investigation in the area of cardiovascular instability in preterm infants,huge gaps in knowledge remain. Study of the hemodynamic characteristics in this population is inadequate. Methods A one-center, prospective, observational longitudinal cohort study at a third level Neonatal Intensive Care Unit enrolled 86 preterm infants. Of these, 46 were low-birth-weight(LBW) newborns of a mean(SD) gestational age of 32.3(1.1) weeks and a birth weight of 2,031(1,684-2,320) g. Forty were very-low-birth-weight(VLBW) newborns with a gestational age of 28.4(1.5) weeks and a birth weight of 1,255(884-1,580) g. All infants underwent Doppler ultrasound examinations at 24, 48, and 72 h after birth. Results SMII, DO_2, MBP, LVCO, CI, and SVI in the VLBW infants were all significantly lower than the LBW infants, but SVRI was not different. Postnatal increases in MBP, SVRI were observed in VLBW and LBW groups that were not associated with changes in LVCO and DO_2. The postnatal pattern of SMII differed between the two groups. SMII increased with postnatal age in the LBW group and did not change significantly in the VLBW group. Conclusions SMII and DO_2 were significantly lower in VLBW neonates during the first 72 h of life, and there was a direct relationship between inotropy, DO_2, and birth weight over a range of maturities at birth. VLBW infants may be at higher risk for cardiac dysfunction when an additional challenge is encountered.[S Chin J Cardiol 2019;20(4):245-251]