Measurement of right and left ventricular ejection fraction in dogs

Three techniques for measurement of right (RVEF) and two techniques for left (LVEF) ventricular ejection fraction were evaluated in five dogs. RVEF was measured with a first-pass radionuclide technique using erythrocytes labelled in vitro with Technetium-99m methylene disphosphonate (MDP) and compared with RVEF measured with a thermodilution technique. Thermodilution-determined RVEF was compared with RVEF values measured with cine angiocardiography. LVEF was measured with a radionuclide ECG-gated equilibrium technique and compared with cine angiocardiography. Measurements were performed before and during a continuous infusion of dopamine. There was an excellent correlation between RVEF measured with the first-pass and the thermodilution technique, rs being 0.86, n = 9, P less than 0.01. When RVEF measured with the thermodilution technique was compared with cine angiocardiography rs was 0.75, n = 10, P less than 0.01. LVEF measured with the ECG-gated equilibrium technique correlated well with cine angiocardiography (rs = 0.91, n = 10, P less than 0.01).     

Right ventricular function in patients with chronic obstructive pulmonary disease

Summary Simultaneous right heart catheterization and radionuclide ventriculography were performed in 27 patients with a wide range of chronic obstructive pulmonary disease. Central hemodynamics and radionuclide studies were done at rest and during exercise. In the resting state the right ventricular ejection fraction (RVEF) was in the normal range (43.3±6%). During exercise a significant (p<0.001) decrease of RVEF to 38.8±6.7% occurred. The pumonary artery mean pressures were 19.9±3.8 at rest. During exercise a significant (p<0.001) increase to 41±9.8 mm Hg occurred. There was a linear relationship between pulmonary pressures and RVEF during exercise in patients with pulmonary artery pressures not exceeding 35 mm Hg. In patients with right ventricular end-diastolic wall thickness 6 mm a curvilinear relationship between these parameters could be observed with a flattening of the curve at higher pressures (>35 mm Hg) and lower ejection fractions (<35% RVEF). Radionuclide venticulography cannot substitute for right heart catheterization. Echocardiography is useful for interpretation of right ventricular ejection fractions in advanced chronic obstructive pulmonary disease.Abbreviations CI Cardiac index (l/min/m²) - CO Cardiac output (l/min) - COPD Chronic obstructive pulmonary disease - FEV₁ Forced expiratory volume in the first second (ml) - HR Heart rate (B/min) - PAd Pulmonary artery diastolic pressure (mm Hg) - PAP Pulmonary artery mean pressure (mm Hg) - PAs Pulmonary artery peak pressure (mm Hg) - PVR Pulmonary vascular resistance (dyn·s·cm^–5) - PwP Pulmonary capillary wedge pressure (mm Hg) - RAP Right arterial pressure (mm Hg) - Raw Airway resistance (cm H₂/l/s) - RNV Radionuclide ventriculogram - RV Residual volume (l) - RVEF Right ventricular ejection fraction (%) - RVEDVI Right ventricular enddiastolic volume index (ml/m²) - RVEDVI SVI RVEF (ml/m²) - RVESVI Right ventricular endsystolic index (m²/m²) - SVI Stroke volume index (ml/m²) - TLC Total lung capacity (l) - VC Vital capacity (l)     

In vitro validation of a right ventricular thermodilution ejection fraction system

Right ventricular ejection fraction (RVEF) is used clinically as an index of right ventricular (RV) pump function. Clinical measurements of RVEF are complicated by the need for complex imaging equipment to compute RV volumes. Recently, the use of thermodilution (TD) methods have been suggested as a simplified means to measure RVEF (RVEF_TD) in patients using rapid response thermistors. Validation, however, by comparison of RVEF_TD and other methodsin vivo, is difficult. Accordingly, thermodilution derived EF measurements (EF_TD) were compared to known values using anin vitro system, with known ejection fractions (EF) set from 17–78% and stroke rates varying independently from 50–100 strokes/min. EF_TD was computed by fitting the downslope of the TD curve to a monoexponential function and computing the time constant of thermal decay. A significant correlation existed between EF_TD and actual EF over the entire study (r=0.96, p<0.001). Bias analysis showed that the points were within a 95% confidence interval of ±12%. Multivariate analysis showed that stroke rate did not significantly affect TD measurements (r=0.03, p>0.7). This study demonstrates that TD accurately predicts EF using anin vitro system and appears to be independent of stroke rate. Thus, TD methods may provide an accurate, simple and reliable means to serially measure RVEF in the clinical setting. This work was supported in part by a Grant-in-Aid from the American Heart Association, and the Bioengineering Alliance of South Carolina.     

组织速度成像与应变率成像技术评价慢性阻塞性肺疾病患者右心室功能

目的应用定量组织速度成像（QTVI）和应变率成像（SRI）技术对慢性阻塞性肺疾病（COPD）患者右心室功能进行检测,旨在探讨两种技术评价COPD患者右心室功能可行性。方法COPD患者38例（男性25例,女性13例,年龄55-71岁,平均年龄62岁）、对照组50例（男性33例,女性17例,年龄48-72岁,平均年龄62岁）,获取心尖四腔TVI图像,测量收缩期峰值运动速度（Vs）、舒张早期峰值应变率（Ve）、收缩期峰值应变率（SRs）、舒张早期峰值应变率（SRe）。结果根据肺动脉压将COPD患者分为肺动脉高压（PAH）组和无肺动脉高压（NPAH）组;与对照组比较,PAH组和NPAH组右心室游离壁和室间隔Vs、Ve、SRs、SRe均显著减低,三尖瓣环Vs、Ve均显著减低;与NPAH组比较,PAH组右心室游离壁和室间隔Vs、Ve、SRs、SRe均显著降低,三尖瓣环Vs、Ve差异无统计学意义。结论COPD患者无论有无肺动脉压增高,其右心室局部与整体功能已经受损,但在肺动脉压增高患者右心室功能受损更重;QTVI与SRI技术可有效评价COPD患者右心室功能。     

Influence of right ventricular pre- and afterload on right ventricular ejection fraction and preload recruitable stroke work relation.

When right ventricular (RV) afterload is abnormally increased, it correlates inversely with right ventricular ejection fraction (RVEF). We tested, whether this would be different with normal afterload. Additionally, we investigated whether previous studies on the slope of RV preload recruitable stroke work (SW) relation, which used rather non-physiological measures to change RV preload, could be transferred to more physiological loading conditions. RV volumes were determined by thermodilution in 16 patients with stable coronary artery disease and normal pulmonary artery pressure (PAP) at rest. Pre- and afterload were varied by body posture, nitroglycerin (NTG) application and by exercise at different body positions. At rest, the change from recumbent to sitting position decreased PAP, cardiac index (Ci), RV diastolic and systolic volumes, and RVEF. Additionally, mean pulmonary artery pressure (MPAP) correlated positively with both RVEF and cardiac index. After correction for mathematical coupling, the RV preload recruitable SW relation was: right ventricular stroke work index (RVSWi) (103 erg m-2)= 8.1 x (RV end-diastolic volume index -4.9), with n=96, r=0.57, P< or =0.001. Exercise abolished this correlation and led to an inverse correlation between RV end-systolic volume (ESV) and RVSW. In conclusion, (i) RVEF correlates positively with RV afterload when afterload varies within normal range; (ii) the slope of the RV preload recruitable SW relation, which is obtained at steady state under normal loading conditions, is substantially flatter than previously described for dynamic changes of RV preload. With increasing afterload, preload loses its determining effect on RV performance, while afterload becomes more important. This puts earlier assumptions of an afterload independent RV preload recruitable SW relation into question.     

Severe chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) exacts a heavy toll on society, yet its prevention, diagnosis and treatment receives inadequate attention from both the medical community and from society at large. Guidelines released in 2001 from the Global Initiative for Chronic Obstructive Lung Disease (GOLD) are aimed at redressing this inequity. In this review, we integrate information from the GOLD guidelines with recent updates on the prevention, treatment and management as related specifically to the most severe form of this disease. In order to help distinguish COPD from other disorders that may mimic or confound its treatment, we place particular emphasis on the definition, underlying pathophysiology and diagnosis of COPD. In addition, we discuss future directions in pharmacotherapy.     

Rethinking chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a complex polygenic disease characterized by an abnormal inflammatory response to smoke, and results in a progressive and debilitating condition with declining lung function. The reasons why some smokers get COPD are not known. We suggest that corticosteroid resistance, which derives from oxidative stress, might actually be the cause of COPD and represent the starting point of the pathology. The absence of response to corticosteroids would let the disease develop, impairing the organism capacity to suppress any kind of inflammatory process. Corticosteroid resistance may derive from smoke induced oxidative stress and plausibly impairs the organism capacity to suppress inflammation. Many factors may contribute to the development and persistence of corticosteroid resistance: inefficient antioxidant defences, a corticosteroid response less efficient or more sensitive to oxidative conditions, and also any other concomitant factor, environmental, genetic or intercurrent, which would contribute to amplify inflammation and hence oxidative stress. One or more of these factors might represent the variable component of the disease, which gives origin to COPD heterogeneity. This hypotheses may also explain why the disease persists after quitting smoking, as an inflammatory process severe enough to generate a strong oxidative stress may support itself by maintenance of corticosteroid resistance.     

Measurement of ejection fraction with standard thermodilution catheters

Right ventricle ejection fraction (RVEF) is clinically used to evaluate right ventricular function. The thermodilution method can be modified to estimate the RVEF. However, this method requires a thermistor with a fast time response in order to yield correct estimates. Digital signal processing techniques that were developed in previous works, allow the use of industry-standard slow time response thermistors for the measurement EF. However, these algorithms were not automated, and the works did not present a complete evaluation of the method's performance. This article presents a modified automated version of these algorithms, and uses numerical and in vitro simulations to test their performance. In the simulations, the measured ejection fraction was compared to the true ejection fraction. RVEFs ranging from 0.20 to 0.80 were tested for heart rates ranging from 30 to 120 heart beats per min. Statistical analysis of data showed that the new method presents an improved performance.     

Association between left ventricular diastolic dysfunction and severity of chronic obstructive pulmonary disease

OBJECTIVES:

The prevalence of electrocardiographic and echocardiographic abnormalities in chronic obstructive pulmonary disease according to disease severity has not yet been established. The aim of this study was to assess the prevalence of electrocardiographic and echocardiographic abnormalities in chronic obstructive pulmonary disease patients according to disease severity.

METHODS:

The study included 25 mild/moderate chronic obstructive pulmonary disease patients and 25 severe/very severe chronic obstructive pulmonary disease patients. All participants underwent clinical evaluation, spirometry and electrocardiography/echocardiography.

RESULTS:

Electrocardiography and echocardiography showed Q-wave alterations and segmental contractility in five (10%) patients. The most frequent echocardiographic finding was mild left diastolic dysfunction (88%), independent of chronic obstructive pulmonary disease stage. The proportion of right ventricular overload (p<0.05) and blockage of the anterosuperior division of the left bundle branch were higher in patients with greater obstruction. In an echocardiographic analysis, mild/moderate chronic obstructive pulmonary disease patients showed more abnormalities in segmental contractility (p<0.05), whereas severe/very severe chronic obstructive pulmonary disease patients showed a higher prevalence of right ventricular overload (p<0.05), increased right cardiac chamber (p<0.05) and higher values of E-wave deceleration time (p<0.05). Age, sex, systemic arterial hypertension, C-reactive protein and disease were included as independent variables in a multiple linear regression; only disease severity was predictive of the E-wave deceleration time [r² = 0.26, p = 0.01].

CONCLUSION:

Chronic obstructive pulmonary disease patients have a high prevalence of left ventricular diastolic dysfunction, which is associated with disease severity. Because of this association, it is important to exclude decompensated heart failure during chronic obstructive pulmonary disease exacerbation.     

Immune response in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major public health problem because of its high prevalence, rising incidence and associated socio-economic cost. The inhalation of toxic particles and gases, mostly tobacco smoke, is the main risk factor for COPD. Yet, not all smokers are equally susceptible to these toxic effects and only a percentage of them develop the disease (so-called ‘susceptible smokers’). This, in combination with the observation that COPD shows familial aggregation, suggests that the genetic background of the smoker is a key element in the pathogenesis of the disease. On the other hand, it is well established that ‘susceptible’ smokers exhibit an enhanced inflammatory response of the lung parenchyma as compared with ‘resistant’ smokers (i.e., those who manage to maintain lung function within the normal age range despite their habit). Importantly, in COPD patients this inflammatory response does not resolve after quitting smoking, again at variance with resistant smokers. All in all, these observations suggest that the pathogenesis of COPD may involve, in some patients, an autoimmune component which contributes to the enhanced and persistent inflammatory response that characterizes the disease. Here we: i) review briefly the pathobiology of COPD; ii) present the available scientific evidence supporting a potential role for autoimmunity in COPD; iii) propose a three-step pathogenic hypothesis in the transition from smoking to COPD; and iv) discuss potential implications for the diagnosis and treatment of this frequent, growing, devastating and costly disease.     

The neutrophil in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a complex, heterogeneous collection of conditions characterized by irreversible expiratory airflow limitation. The disease involves a multifaceted progressive inflammatory process leading to the development of mucus hypersecretion, tissue destruction, and disruption to the normal repair and defense mechanisms. The result is increased resistance to airflow in small conducting airways, change in lung compliance, and the premature collapse of airways during expiration that leads to air trapping. Neutrophils are necessary in healthy lungs; they are an important component of innate immunity, protecting healthy individuals against infection. However, in COPD, they play a role in the destructive processes that characterize the disease. They can be responsible for significant damage when they accumulate at sites of inflammation and are harmful to healthy tissue. In recent years, increased understanding of the role of neutrophils has led to improved knowledge of the pathogenesis of COPD and allowed new avenues of treatment to be investigated.