THE INFLUENCE OF CAPTOPRIL AND NALOXONE ON THE VALSALVA MANOEUVRE AND SYSTOLIC TIME INTERVALS IN HEALTHY VOLUNTEERS

1. The aim of the study was to ascertain whether the inhibition of the sympathetic nervous system by angiotensin-converting enzyme (ACE) inhibitors is mediated by endogenous opioids. Naloxone was used to evaluate the effects of the latter on systolic time intervals (STI) and Valsalva manoeuvre-induced blood pressure and heart rate changes. 2. Baseline recordings were done in 12 healthy male volunteers and repeated 2h after oral administration of 75 mg of captopril and again after naloxone 0.4 mg/kg was administered intravenously over 10 min. 3. After captopril there was a significant reduction in systolic (P<0.02) and mean blood pressure (P<0.04) without any changes in heart rate. Furthermore, captopril increased the Valsalva ratio (P<0.06) but did not influence inotropism as indicated by STI. Naloxone did not influence any of these findings. 4. The changes in the Valsalva ratio after captopril were mediated by an increase in the maximum bradycardia in nine of the 12 subjects. 5. The results indicate that endogenous opioids do not play a role in the putative sympatholytic effect of ACE inhibition.     

U波倒置40例临床分析

U波倒置40例,其中孤立性U倒16例(40％),复合性U倒24例(60％)。U波倒置常见于左心前导联V_5V_6,呈现左室肥厚及负荷加重,心电图示“左室劳损”型。U波倒置严重合并症,除心力衰竭外,还有急性心肌梗塞和室性期前收缩。笔者认为,通过本文分析,UV_5倒置对临床诊断冠心病,高血压等是有价值的。     

五参平律汤合律平治疗早搏96例临床观察

目的：观察五参平律汤合心律平对早搏的临床疗效,探讨可能的作用机理,方法：在对症治疗的基础上,随机分成五参平律汤合心律平组（治疗组）,和单用心律平组（对照组）进行临床观察,结果：治疗组抗早搏总有效率为865,对照组为71．75,两组差异显著,P＜0．01。结论：五参平律汤合心律平治疗早搏明显优于单用心律平,可能机能为补心平律,活血通络,改善心肌营养,抑制异位节律及折返传导,是否同时具有抗心律平的致心律失常作用有待以后验证。     

Redefining Diastolic Dysfunction Grading: Combination of E/A ≤0.75 and Deceleration Time >140 ms and E/ε′ ≥10

ObjectivesThis study sought to examine left atrial (LA) mechanics and the prognostic impact of patients with echocardiographic findings of E/A ratio ≤0.75, deceleration time (DcT) of mitral E-wave >140 ms, but E/ε′ ≥10.BackgroundTraditional diastolic dysfunction (DD) grading system could not classify every patient into a specific group. We considered the group of patients with E/A ≤0.75, DcT >140 ms, but E/ε′ ≥10 (proposed new DD grade) as a new group in the DD grading system.MethodsA total of 1,362 consecutive patients were stratified according to the new DD grading system, and the LA volumes, strain, and strain rates were measured by 2-dimensional speckle-tracking analysis. All patients were followed up to determine cardiac death and major adverse cardiac events.ResultsAn E/A ≤0.75, DcT >140 ms, but E/ε′ ≥10 was observed in 227 patients (17%). LA volumes in patients with the new DD grade were between those of the impaired relaxation group and the pseudonormal group. LA strain of the new DD grade was similar to that of the pseudonormal group, whereas LA booster function was preserved as in the impaired relaxation group. During a mean follow-up of 3.0 ± 1.1 years, 25 patients had cardiac death and 61 had major adverse cardiac events. Event-free survival for major adverse cardiac events of the new DD grade was worse than that of the impaired relaxation group but similar to that of the pseudonormal group.ConclusionsThe new DD grade is frequently observed and has a prognosis similar to that of the pseudonormal group but significantly worse than that of the impaired relaxation group. However, LA booster function was maintained at the expense of LA volume enlargement. Thus, the new grade should be a distinct entity for routine DD grading.     

Assessment of Left Ventricular Viscoelastic Components Based on Ventricular Harmonic Behavior

Background: Assessment of left ventricular (LV) function with an emphasis on contractility has been a challenge in cardiac mechanics during the recent decades. The LV function is usually described by the LV pressure-volume (P-V) relationship. Based on this relationship, the ratio of instantaneous pressure to instantaneous volume is an index for LV chamber stiffness. The standard P-V diagrams are easy to interpret but difficult to obtain and require invasive instrumentation for measuring the corresponding volume and pressure data. In the present study, we introduce a technique that can estimate viscoelastic properties, not only the elastic component but also the viscous properties of the LV based on oscillatory behavior of the ventricular chamber and it can be applied non-invasively as well. Materials and Methods: The estimation technique is based on modeling the actual long axis displacement of the mitral annulus plane toward the cardiac base as a linear damped oscillator with time-varying coefficients. Elastic deformations resulting from the changes in the ventricular mechanical properties of myocardium are represented as a time-varying spring while the viscous components of the model include a time-varying viscous damper, representing relaxation and the frictional energy loss. To measure the left ventricular axial displacement ten healthy sheep underwent left thoracotomy and sonomicrometry transducers were implanted at the apex and base of the LV. The time-varying parameters of the model were estimated by a standard Recursive Linear Least Squares (RLLS) technique. Results: LV stiffness at end-systole and end-diastole was in the range of 61.86–136 dyne/g.cm and 1.25–21.02 dyne/g.cm, respectively. Univariate linear regression was performed to verify the agreement between the estimated parameters, and the measured values of stiffness. The averaged magnitude of the stiffness and damping coefficients during a complete cardiac cycle were estimated as 58.63±12.8 dyne/g.cm and 0 dyne.s/g.cm, respectively. Conclusion: The results for the estimated elastic coefficients are consistent with the ones obtained from force-displacement diagram. The trend of change in the estimated parameters is also in harmony with the previous studies done using P-V diagram. The only input used in this model is the long axis displacement of the annulus plane, which can also be obtained non-invasively using tissue Doppler or MR imaging.     

大鼠离体心脏缺血-再灌注过程的功能变化

目的 建立大鼠离体心脏缺血-再灌注(I/R)损伤模型,观察I/R过程心脏舒缩功能与冠脉流量变化. 方法 大鼠离体心脏采用Langendorff法灌流,对照组(n=8)心脏连续灌流80 min;I/R组(n=8)心脏缺血40 min再灌注40 min.实验过程实时动态检测心率(min-1)、心肌收缩幅度(g)与最大收缩速度(dT/dtmax,g/ms)、最大舒张速度(-dT/dtmax,g/ms)、心肌静息张力(g)、冠脉流量(液滴,min-1). 结果 与对照组比较,I/R组心脏缺血后心搏停止,20 min后心肌静息张力上升(P＜0.05);再灌注后心肌张力仍高;心搏恢复但心率、心脏收缩幅度、最大收缩速度、最大舒张速度均降低(P＜0.05～0.001);再复灌注初冠脉流量恢复正常,10 min后呈下降性变化(P＜0.05～0.001). 结论 大鼠离体心脏缺血40 min再灌注40 min导致I/R损伤,该模型制备及功能评价方法简便可靠.