Relationship of Microvascular Obstruction with Global and Regional Myocardial Function Determined by Cardiac Magnetic Resonance after ST-Segment Elevation Myocardial Infarction

Objective To investigate the impact of microvascular obstruction(MVO)on the global and regional myocardial function by cardiac magnetic resonance feature-tracking(CMR-FT)in ST-segment-elevation myocardial infarction(STEMI)patients after percutaneous coronary intervention.Methods Consecutive acute STEMI patients who underwent cardiac magnetic resonance imaging 1-7 days after successful reperfusion by percutaneous coronary intervention treatment were included in this retrospective study.Based on the presence or absence of MVO on late gadolinium enhancement images,patients were divided into groups with MVO and without MVO.The infarct zone,adjacent zone,and remote zone were determined based on a myocardial 16-segment model.The radial strain(RS),circumferential strain(CS),and longitudinal strain(LS)of the global left ventricle(LV)and the infarct,adjacent,and remote zones were measured by CMRFT from cine images and compared between patients with and without MVO using independent-samples t-test.Logistic regression analysis was used to assess the association of MVO with the impaired LV function.Results A total of 157 STEMI patients(mean age 56.66±11.38 years)were enrolled.MVO was detected in 37.58%(59/157)of STEMI patients,and the mean size of MVO was 3.00±3.76 mL.Compared with patients without MVO(n=98),the MVO group had significantly reduced LV global RS(t=-4.30,P<0.001),global CS(t=4.99,P<0.001),and global LS(t=3.51,P=0.001).The RS and CS of the infarct zone in patients with MVO were significantly reduced(t=-3.38,P=0.001;t=2.64,P=0.01;respectively)and the infarct size was significantly larger(t=8.37,P<0.001)than that of patients without MVO.The presence of LV MVO[OR=4.10,95%CI:2.05-8.19,P<0.001]and its size[OR=1.38,95%CI:1.10-1.72,P=0.01],along with the heart rate and LV infarct size were significantly associated with impaired LV global CS in univariable Logistic regression analysis,while only heart rate(OR=1.08,95%CI:1.03-1.13,P=0.001)and LV infarct size(OR=1.10,95%CI:1.03-1.16,P=0.003)were independent influencing factors for the impaired LV global CS in multivariable Logistic regression analysis.Conclusion The infarct size was larger in STEMI patients with MVO,and MVO deteriorates the global and regional LV myocardial function.

Assessment of Regional Myocardial Function in Patients with Hypertrophic Cardiomyopathy by Tissue Strain Imaging

The value of tissue strain imaging （SI） in regional myocardial systolic and diastolic func tion assessment was studied. In 18 patients with nonobstructive hypertrophic cardiomyopathy （HCM） and 20 age-matched healthy subjects, regional myocardial longitudinal peak systolic strain in eject time （represented by εet） was measured at basal, mid and apical segments of septal, lateral and posterior walls of the left ventricle （LV） and compared between groups, εet had no significant difference between segments in control group （P〉0.05）, which displayed a decreasing trend from basal segments to apical ones. εet in the HCM group was significantly decreased （P（0. 05） as compared with that in the healthy group. In the HCM group, εet in the midseptum was significantly less than at the basal and apical septum, and was also less than at the rest LV walls in the same group （P〉0.01）. The systolic reversed εet was noticed in 35% of the hypertrophic segments in HCM group. Significantly negative correlation existed between the absolute value of εet and wall thickness in the midseptum （r= -0.83）. The post-systolic strain（PSS） segment number the and amplitudes in healthy group were significantly less than those in HCM group （P〈0.05）. Both regional myocardial systolic and diastolic functions were impaired in hypertrophic or non-hypertrophic segments in patients with the HCM, especially in hypertrophic segments. Strain imaging technique is a sensitive and accura tool in myocardial dysfunction assessment.

Effect of Moxibustion on Cardiac Remodeling and Myocardial Function in Rats with Exercise-Induced Fatigue

Objective:To explore the effect of moxibustion at Shenque(CV8)on myocardial structure and function in rats with exercise-induced fatigue.Methods:A 12-week treadmill training program was used to establish a rat model of exercise-induced fatigue.Fifty-six male SD rats removed six rats that did not reach the molding condition,Remaining rats were randomly divided into the following five groups:a normal group(n=10)that did not under go the exercise routine and were not treated,a control group(n=10)that did not under go the exercise routine,but received a mild dose of moxibustion at"Shenque"(CV 8)for 15 min,an untreated group(n=10)that received no treatment after exercise,a CV 8 group(n=10)that received a mild dose of moxibustion at"Shenque"(CV 8)for 15 min after exercise,a non-acupoint(tail)group(n=10)that received a mild dose of moxibustion at"non-acupoint"for 15 min after exercise.At one hour after the end of the 12-week training program,the left ventricular diastolic volume(LVDV),left ventricular systolic volume(LVSV),peak early diastolic mitral blood flow velocity(E),and peak late diastolic mitral blood flow velocity(A)were measured,and the E/A ratio were calculated.The serum myoglobin(Mb),creatine kinase-muscle/brain(CK-MB),and cardiac troponin-I(cTnI)levels were detected using an automatic biochemical analyzer.Results:When the values obtained before and after treatment were compared within the same groups,the LVDV,LVSV,E,and A were increased(P<0.05 or P<0.01),and the E/A were decreased(P<0.01)in the untreated group and the tail group.Regarding inter-group comparisons,the LVDV,LVSV,E,and A were increased(P<0.05 or P<0.01),and the E/A were decreased(P<0.01)in the untreated group and the tail group compared to the normal group and control group.Compared to the untreated group and the tail group,the LVDV,LVSV,E,and A were decreased(P<0.01)and the E/A were increased(P<0.01)in the CV 8 group.Compared to the normal group and the control group,the serum Mb,CK-MB,and cTnI levels were increased(P<0.01)in the untreated group and the tail group,and the serum Mb and CK-MB levels were also increased(P<0.01)in the CV 8 group.Compared to the untreated group and the tail group the serum Mb,CK-MB,and cTnI levels in the CV 8 group were decreased(P<0.01).Conclusions:Moxibustion at Shenque(CV8)can effectively prevent cardiac structural changes caused by exercise-induced fatigue and enhance heart function.This treatment does not have side effects in healthy rats and is a safe and effective technique..

Effect of Amino Acid Cardioplegia on Myocardial Metabolism and Function of Ischemic Canine Heart

To evaluate the effect of amino acid cardioplegia on myocardial metabolism and function of ischemic canine heart, canine cardiopulmonary bypass (CPB) model was established and the dog heart was subjected to a 120 min ischemic arrest. Animals were divided into 3 groups, group 1:warm blood cardioplegia induction and terminal perfusion plus 4 C ST. Thomas hospital solution (STS)during ischemia;group 2: warm blood cardioplegia enriched with amino acid (L-asparte and L-glutamate 13 mmol/L each) and STS without amino acid (A.G.) and group 3:both warm blood cardioplegic solution and STS enriched with A. G..The result demonstrated that the cardiac function of animals in group 2 and 3 had a significantly better recovery after ischemic-re-perfusion. By the end of ischemia the content of myocardial ATP in group 3 was distinctly higher than that in group 1(P<0. 05), with the release of cardiac enzyme being the least. Myocardial ultra-structure almost remained intact before and after ischemia. Our experiment suggests that the cardioplegia arrest with warm blood and cold crystalloid solution enriched with amino acids could diminish the ischemia-re-perfusion injuries of the heart and enhance the effect of myocardial protection.

Viable Myocardium Impact on Left Ventricular Function after Late Revascularization of Infarct-related Artery in Acute Myocardial Infarction

Objectives The long-term benefit of late reperfusion of infarct-related artery （IRA） after acute myocardial infarction （AMI） is controversial, and the benefit mechanisms remain uncertain. Low dose dobutamine stress echocardiography （LDSE） can identify viable myocardium and predict improvement of wall motion after revascularization. Methods Sixtynine patients with first AMI who did not received early reperfusion therapy were studied by LDSE at 5 to 10 days after AMI. Wall motion abnormality and left ventricular size were measured at the same time. Successful PCI were done in all patients at 10 to 21 days after AMI onset. Patients were divided in two groups based on the presence or absence of viable myocardium. Echocardiography was repeated six months later. Results There were 157 motion abnormality segments. 89 segments （57%） were viable during LDSE. 26 patients （38%） with viability and 43 （62%） without. In viable group, left ventricular ejection fraction （LVEF） was increased （P 〈 0.05）, and left ventricular end systolic volume index （LVESVI） and wall motion score （WMS） were decreased （P 〈 0.05 and P 〈 0.01） significantly at 6 months compared with baseline. But in patients without viability, LVEF was decreased （P 〈 0.01）, and LVESVI and left ventricular end diastolic volume index （LVEDVI） were increased （P 〈 0.05） significantly after 6 months, and the WMS did not changed （P 〉 0.05 ）. LVEF increased （P 〈 0.05 ） and WMS decreased （P 〈 0.05） on LDSE during acute phase in patients with viability, but they were not changed in the nonviable group. Conclusions Late revascularization of IRA in patients with presence of viable myocardium after AMI is associated with long-term preservation left ventricular function and less ventricular remodeling. Improvement of left ventricular systolic function on LDSE indicates late phase recovery of left ventricular function after late revascularization.

New Insight in the Assessment of Left Ventricular Function in Paradoxical Low Flow Aortic Stenosis Patients with Normal Left Ventricular Ejection Fraction: A Mini-Review

Paradoxical valvular aortic stenosis (VAS) is a challenging area of clinical cardiology for the practitioners. It involves a small aortic valve area, low flow rate and mean pressure gradient although there is normal left ventricular ejection fraction. The aim of this study was to assess left ventricular (LV) dysfunction in a symptomatic severe aortic valve stenosis which is of crucial importance in identifying patients at risk of heart failure, postoperative complications and increased mortality. There are new insights which are involved in assessment of LV myocardial function including global longitudinal strain (GLS) by two-dimensional speckle tracking echocardiography (2D STE), myocardial performance index (MPI) and maximum rate of LV pressure rise (+dP/dt) during isovolumetric contraction time of the LV. This information can provide both diagnostic and prognostic information in addition to standard echocardiographic and clinical parameters. However, a profound understanding of the complex interaction between loading conditions, chamber geometry and contractility is necessary for the correct interpretation of myocardial deformation in order to draw appropriate conclusions in patients with aortic valve disease. This mini review is related to new and novel insights into the assessment of left ventricular function (LVF) in paradoxical low flow aortic stenosis patients with normal left ventricular ejection fraction (LVEF).

Left-sided vagus nerve stimulation improves cardiopulmonary resuscitation outcomes in rats as effectively as right-sided vagus nerve stimulation

BACKGROUND: Our group previously reported that right-sided vagus nerve stimulation(RVNS) significantly improved outcomes after cardiopulmonary resuscitation(CPR) in a rat model of cardiac arrest(CA). However, whether left-sided vagus nerve stimulation(LVNS) could achieve the same effect as RVNS in CPR outcomes remains unknown.METHODS: A rat model of CA was established using modified percutaneous epicardial electrical stimulation to induce ventricular fibrillation(VF). Rats were treated with LVNS or RVNS for 30 minutes before the induction of VF. All animals were observed closely within 72 hours after return of spontaneous circulation(ROSC), and their health and behavior were evaluated every 24 hours.RESULTS: Compared with those in the RVNS group, the hemodynamic measurements in the LVNS group decreased more notably. Vagus nerve stimulation(VNS) decreased the serum levels of tumor necrosis factor-alpha(TNF-α) and the arrhythmia score, and attenuated inflammatory infiltration in myocardial tissue after ROSC, regardless of the side of stimulation, compared with findings in the CPR group. Both LVNS and RVNS ameliorated myocardial function and increased the expression of α-7 nicotinic acetylcholine receptor in the myocardium after ROSC. Moreover, a clear improvement in 72-hour survival was shown with VNS pre-treatment, with no significant difference in efficacy when comparing the laterality of stimulation. CONCLUSIONS: LVNS may have similar effects as RVNS on improving outcomes after CPR.

BENEFICIAL EFFECTS OF NTG ON LEFT VENTRICULAR VOLUMES AND SYSTOLIC FUNCTION IN PATIENTS WITH MYOCARDIAL INFARCTION

The effect of sublingual administration and intravenous drip of nitroglycerin (SLNTG and IVNTG) on left ventricular volumes (LVVs) were studied and systolic function was quantitatively assessed with two-dimensional echocardiography (2DE) in 28 patients with myocardial infarction (MI), including 13 cases without heart failure (MI-NHF) in one group and 15 with heart failure (MI-HF) in another. The results showed that after SLNTG and IVNTG in both groups the heart rate (HR) increased significantly (P< 0.05-0.001); the systolic blood pressure (SBP) decreased significantly (P< 0.05-0.001); the diastolic blood pressure (DBP) was not significantly changed (all P>0.05); the left ventricular end-diastolic and end-systolic volumes (EDV and ESV) both significantly reduced [EDV: decreased by 5.8-11.6% (-13.2-19.0 ml), P< 0.05-0.001; ESV: decreased by 9.6-16.6% (-8.6-17.3 ml), P< 0.05-0.001)1; the left ventricular ejection fraction (LVEF) all significantly elevated (increased by 6.6%-9.4% (3.2%-3.4%), P < 0.05-0.001] except in MI-NHF group after IVNTG; the segmental EF of normal and hypokinetic segments also significantly increased (P<0.05-0.001). The results suggest that NTG could beneficially reduce left ventricular EDV and ESV; and improve or strengthen its global and segmental systolic function in MI patients, particularly noticeable in patients with heart failure.

THE EFFECT OF LOW DOSE ASPIRIN ON THE PLATELET FUNCTION IN PATIENTS WITH ACUTE MYOCARDIAL INFARCTION (AMI)

To assess the optimal dose of aspirin （ASA） in the treatment of AMI, 60 cases of AMI: 1. admitted within 24 hours after onset of illness, 2. ASA not used within one week before, 3. any other drugs influencing the platelet function also not used during the course of study, were randomized into two groups, 30 cases each: one with conventional therapy as control, the other combined with daily oral ASA 100mg. They were matched in sex, age, infarct site and coexistent conditions （hypertension, diabetes mellitus, hyperlipemia, smoking etc.）. The second group was further divided into subgroup I with serum peak CK<1000 U/L and subgroup Ⅱ with serum peak CK>1000 U/L. The parameters of platelet function including plasma TXB/6-keto-PGF, platelet aggregation induced by 5-HT and epinephrine were studied on different days for 3 weeks. Twenty healthy persons were selected for normal value of platelet function.

The impact of different doses of atorvastatin on plasma endothelin and platelet function in acute ST-segment elevation myocardial infarction after emergency percutaneous coronary intervention

Objective To investigate the effects of different doses of atorvastatin on plasma endothelin and platelet function in acute ST-segment elevation myocardial infarction(STEMI)patients after emergency percutaneous coronary intervention(PCI).Methods A total of 120 patients with acute STEMI treated with emergency PCI were enrolled and randomly divided into 20 mg of atorvastatin treatment group(standard group,n=60),and 40 mg of atorvastatin treatment group(intensive group,n=60).

The Level of Serum Intact Terminal Peptide of Procollagen and Its Clinical Significance in Patients with Chronic Keshan Disease

Objectives To evaluate the changes of serum intact terminal peptide of procollagen in patients with chronic Keshan disease (KD) and investigate their clinical significance. Methods The concentrations of serum intact N-terminal peptide of type procollagen (P NP) and intact N-terminal peptide of type procollagen were measured by radioimmunoassay in 35 patients with chronic KD and 31 normal control. Doppler ultrasounds was used to determine several parameters of left ventricular systole and diastole functions. Results The concentration of serum P NP (74.07±16.74)μg/L and the ratio of P NP/ P NP (18.02 ±4.60) in chronic KD were significantly increased as compared to the control (39.63±12.07 μg/L, 12.12±4.24; P< 0.001). Serum P NP (4.19±0.64)μg/L in chronic KD was higher than that in the control (3.36±0.65 μg/L,P < 0.001) too. The higher of serum concentration of P NP and the ratio of P NP/ P NP, the worse of cardiac function in patients with chronic KD. A negative correlation was found between serum P NP/ P NP, P NP and VE/VA, LVEF (γ=-0.4502, -0.4608, P< 0.01 and γ=-0.3936, -0.3904, respectively; P<0.05). Conclusions These findings suggested that tissue synthesis of collagen type and type was abnormally increased in chronic KD. On the other hand, our results indicated that P NP and P NP were related to several functional alterations of the left ventricle. Serum procollagen peptide measurements might therefore provide indirectly diagnostic information on myocardial fibrosis associated with chronic KD.

Cardiac-specific knockout of ET_(A)receptor mitigates low ambient temperature-induced cardiac hypertrophy and contractile dysfunction

Cold exposure is associated with oxidative stress and cardiac dysfunction.The endothelin(ET)system,which plays a key role in myocardial homeostasis,may participate in cold exposure-induced cardiovascular dysfunction.This study was designed to examine the role of ET-1 in cold stress-induced cardiac geometric and contractile responses.Wild-type(WT)and ETA receptor knockout(ETAKO)mice were assigned to normal or cold exposure(48C)environment for 2 and 5 weeks prior to evaluation of cardiac geometry,contractile,and intracellular Ca21 properties.Levels of the temperature sensor transient receptor potential vanilloid(TRPV1),mitochondrial proteins for biogenesis and oxidative phosphorylation,including UCP2,HSP90,and PGC1a were evaluated.Cold stress triggered cardiac hypertrophy,depressed myocardial contractile capacity,including fractional shortening,peak shortening,and maximal velocity of shortening/relengthening,reduced intracellular Ca21 release,prolonged intracellular Ca21 decay and relengthening duration,generation of ROS and superoxide,as well as apoptosis,the effects of which were blunted by ETAKO.Western blotting revealed downregulated TRPV1 and PGC1a as well as upregulated UCP2 and activation of GSK3b,GATA4,and CREB in cold-stressed WT mouse hearts,which were obliterated by ETAKO.Levels of HSP90,an essential regulator for thermotolerance,were unchanged.The TRPV1 agonist SA13353 attenuated whereas TRPV1 antagonist capsazepine mimicked cold stress-or ET-1-induced cardiac anomalies.The GSK3b inhibitor SB216763 ablated cold stress-induced cardiac contractile(but not remodeling)changes and ET-1-induced TRPV1 downregulation.These data suggest that ETAKO protects against cold exposure-induced cardiac remodeling and dysfunction mediated through TRPV1 and mitochondrial function.

Long-term effects of bone marrow-derived cells transplantation in patients with acute myocardial infarction： a meta-analysis

Background The long-term effects of bone marrow-derived cells （BMC） transplantation in patients with acute myocardial infarction （AMI） have not been established. The present meta-analysis of randomized controlled trials with follow-up 〉2 years was performed to investigate the long-term effects of BMC therapy in patients after AMI. Methods Specific terms were used to conduct a systematic literature search of MEDLINE, EMBASE, the Cochrane Library and the Cochrane Central Register of Controlled Trials, and the China Biological Medicine Disk database from their inception to March 2012. A standardized protocol was used to extract information, and random effect model was used to analyze all data except major adverse events. Results Five trials comprising 510 patients were included. Compared with controls, BMC therapy significantly improved left ventricular ejection fraction （LVEF） （4.18%, 95% CI： 2.02% to 6.35%, P=-0.0002）, while mildly but not significantly reduced left ventricular end-systolic volume （-4.47 ml, 95% CI： -10.92 to 1.99, P=-0.17） and left ventricular end-diastolic volume （-2.29 ml, 95% CI： -9.96 to 5.39, P =0.56）. Subgroup analysis revealed that significant improvement of LVEF induced by BMC therapy could be observed in patients with baseline LVEF 〈42%, but disappeared in those with baseline LVEF 〉42%. There were trends in favor of BMC therapy for most major clinical adverse events, though most differences were not significant. Conclusions Intracoronary BMC infusion in patients with AMI seems to be safe and may further improve LVEF on top of standard therapy; especially the beneficial effects could last for long term. The findings need to be validated in the future.