Stress Induced Right Ventricular Diastolic Dysfunction in Non-Severe Chronic Obstructive Pulmonary Disease - The Role of Oxidative Stress and Inflammation

Research Article

Austin J Clin Cardiolog. 2020; 6(1): 1068.

Stress Induced Right Ventricular Diastolic Dysfunction in Non-Severe Chronic Obstructive Pulmonary Disease - The Role of Oxidative Stress and Inflammation

Cherneva ZV1*, Youroukova VM2 and Cherneva RV2

1Department of Cardiology, Medical Institute of the Ministry of Internal Affairs, Bulgaria

2Department of Respiratory Diseases, Medical University, Bulgaria

*Corresponding author: Zheyna Vlaeva Cherneva, Department of Cardiology, Medical Institute of the Ministry of Internal Affairs, Sofia, Bulgaria

Received: July 10, 2020; Accepted: August 29, 2020; Published: September 05, 2020


Background: Oxidative stress and inflammation have been implicated in the pathogenesis of Diastolic Dysfunction (DD) and are both present in chronic obstructive pulmonary disease (COPD). Our aim was to evaluate the role of 8-isoprostane, prostaglandin E2 and resistin for stress induced right ventricular DD (RVDD) in non-severe COPD.

Methods: 104 patients with non-severe COPD (FEV1>50%) and preserved left ventricular ejection fraction >50% underwent cardio-pulmonary exercise testing (CPET). Echocardiography was performed before CPET and 1-2 minutes after peak exercise. Peak E/e’ ratio>6 was a marker for stress RVDD. To measure urine concentration of 8-isoprostanes, prostaglandine-E2 and plasma resistin levels mass spectrometry and ELISA were applied.

Results: Patients were divided into two groups: With (82) and without stress RVDD (22). In subjects with and without RVDD the levels of 8-isoprostane were (30.78 vs 30.41μmol/l/cre, p-0.847); prostaglandin E2 - (49.73 vs 62. 19 μmol/l/ cre, p-0.014); resistin plasma levels (18.91 vs 5.47ng/ml, p-0.027). Resistin and prostaglandine E2 correlated to stress RV E/e’, but were not independent indices for it. RAVI (cut-off 20.55 ml/m2; sensitivity 86%; specificity 86%), RVWT (cut-off 5.25 mm; sensitivity 100%; specificity 63%) and RV E/A at rest (cut-off 1.05; sensitivity 79.7%; specificity 90.5%) independently predicted stress RV E/e’ with the accuracy of 92%.

Conclusion: Patients with stress RVDD demonstrate similar levels of oxidative stress. Prostaglandine E2 may have protective role in RV remodeling, while resistin plasma levels contribute to RVDD pathogenesis. Only RAVI, RVWT, RV E/A and RV E/e’ ratio at rest may be used as independent predictors for stress RVDD. 250

Keywords: Chronic Obstructive Pulmonary Disease, Heart Failure with Preserved Ejection Fraction,Inflammation, Oxidative Stress, Stress Echocardiography


COPD: Chronic Obstructive Pulmonary Disease; DD: Diastolic Dysfunction; RVDD: Right Ventricular Diastolic Dysfunction; CPET: Cardio-Pulmonary Exercise Testing; CV:Cardio-Vascular; LVDD: Left Ventricular Diastolic Dysfunction; RAVI: Right Atrium Volume Index; RVWT: Right Ventricle Wall Thickness; AT: Acceleration Time; PASP: Pulmonary Arterial Systolic Pressure; PAP: Pulmonary Arterial Pressure; TAPSE: Tricuspidal Annular Plane Systolic Excursion; DH: Dynamic Hyperinflation; FRC: Functional Residual Capacity; TLC: Total Lung Capacity; EELV: End-Expiratory Lung Volume; HRAM: High Resolution Accurate Mass; RELM: Rodent Resistin-Like Molecules; ROS: Reactive Oxidative Species; mMRC: Medical Research Council; O2 pulse: Oxygen Pulse; VE: Minute Ventilation; RER: Respiratory Exchange Ratio; V’O2: Oxygen Consumption; VE/VCO2 slope: Ventilatory Efficiency


Cardio-Vascular (CV) comorbidity in COPD is assumed as “Cardio-Pulmonary Continuum” rather than being attributed to shared risk factors. Cardio-respiratory interactions are not restricted to certain structural, haemodynamic, vascular or genetic parameters and both disease states are related with oxidative stress and systemic inflammation [1,2].

Contemporary investigational methods demonstrate that COPD patients have small RV dimensions and RV hypertrophy- factors, predisposing to Right Ventricular Diastolic Dysfunction (RVDD) [3-6]. RVDD is an early sign of pulmonary vasculopathy and precedes the clinical/echocardiographic manifestation of pulmonary hypertension [7-9]. Right ventricular dysfunction and pulmonary vessel impairment may be essential contributors for dyspnea and limited physical activity even in non-severe forms of COPD [10,11].

RVDD detection is thus essential for the early diagnosis of pulmonary vasculopathy in COPD management and physical activity improvement. The simultaneous performance of stressechocardiography and cardio-pulmonary exercise testing may provide timely detection of RVDD in COPD patients with exertional dyspnoea.

Oxidative stress and inflammation in addition tointrathoracic and haemodynamic pressure oscillations have been assumed as leading factors for both right and left ventricular diastolic remodeling in COPD. Assuming this we set the followingaims: 1) to detect the frequency of stress RVDD- in non-severe COPD patients,free of overt cardiovascular pathology who complain of exertional dyspnea; 2) to establishwhichechocardiographic parameters at rest may be predictors for stress RVDD; 3) to establish which inflammatory (resistin, prostaglandine E2) and oxidative stress (8-isoprostane) markers are predictors for stress RVDD.

Materials and Methods

Patients and study protocol

It was a retrospective study that was performed in 224 clinically stable outpatients, diagnosed with COPD at the University Hospital for Respiratory Diseases “St. Sophia”, Sofia. Only 163 of them met the inclusion criteria: The inclusion criteria are: 1) non-severe COPD (post bronchodilator FEV1/FVC<70%; FEV1/ > 50%); 2) preserved left ventricular systolic function LVEF>50%; 3) lack of overt cardiovascular disease; 4) exertional dyspnea. All the subjects had exertional dyspnoea, but a total of 104 patients (64 men, 40 women; mean age of 62.9±7.5 years) were considered eligible, assuming the exclusion criteria. The recruitment period was between May 2017-April 2018, and was approved by the local Ethical Committee (protocol 5/12.03.2018). All the patients signed informed consent before their participation. They were preliminary acquainted with the aim of the study, its scientific value and the potential presentation of data at different forums.

The following exclusion criteria were considered: 1) left ventricular ejection fraction (LVEF) < 50%; 2) left ventricular diastolic dysfunction at rest more than first grade; 3) presence of echocardiographic criteria of pulmonary hypertension (systolic pulmonary arterialpressure > 36 mmHg, maximum velocity of the tricuspid regurgitation jet > 2.8 m/s; 4) valvular heart disease; 5) documented cardiomyopathy; 6) severe uncontrolled hypertension (systolic blood pressure > 180 mmHg and diastolic blood pressure >90 mmHg); 7) atrial fibrillation or malignant ventricular arrhythmia; 8) ischaemic heart disease; 9) anaemia; 10) diabetes mellitus; 11) cancer; 12) chronic kidney disease; 13) recent chest or abdominal surgery; 14) recent exacerbation (during the last three months); 15) recent change (during the last three months) in medical therapy.


Pulmonary Function Testing: All the subjects underwent preliminary clinical examination which included chest X-ray, spirometry, electrocardiogram, echocardiography. Those eligible for the study performed spirometry and exercise stress test. They were performed on Vyntus, Cardio-pulmonary exercise testing (Carefusion, Germany) in accordance with ERS guidelines [12]. Only patients with mild/ moderate airway obstruction (FEV1 >50%) were selected.

Dynamic hyperinflation (DH): Body plethysmography (residual volume (RV), functional residual capacity (FRC), total lung capacity (TLC)) was performed on (Vyntus, body plethysmograph, Care Fusion, Germany) using European and American Thoracic Society guidelines [12].Changes in operational lung volumes were derived from measurements of dynamic inspiratory capacity (IC), assuming that total lung capacity (TLC) remained constant during exercise [13,14]. This has been found to be a reliable method of tracking acute changes in lung volumes [13-15]. IC was measured at the end of a steady-state resting baseline, at 2 min intervals during exercise, and at end exercise. End-expiratory lung volume (EELV) was calculatedfrom IC maneuversatrest, every 2 minutes during exercise and at peak exercise (Vyntus).In these maneuvers, after EELV was observed to be stable over 3-4 breaths, subjects were instructed to inspire maximally to TLC. For each measurement, EELV was calculated as resting TLC minus IC, using the plethysmographic TLC value. Dynamic IC (ICdyn) was defined as resting IC minus IC at peak exercise [16]. Dynamic hyperinflation (DH) was defined as a decrease in IC from rest of more than 150 mL or 4.5% pred at any time during exercise [16].

Stress test protocol - cardio-pulmonary exercise testing (CPET): All the patients underwent symptom limited incremental exercise stress test following the guidelines [17]. A continuous ramp protocol was applied. After two minutes of unloaded pedaling (rest phase- 0W), a three-minute warm-up phase (20W) followed. The test phase included 20W/2min load increments.Patients were instructed to pedal with 60-65 rotations per minute. Patients’ effort was considered to be maximal if two of the following criteria emerged: predicted maximal HR is achieved; predicted maximal work is achieved; ’VE/’VO2>45, RER >1.10 as recommended by the ATS/ACCP [18]. A breath-bybreath analysis was used for expiratory gases evaluation.’VO2 (mL/ kg/min), ’VCO2 (L/min), ‘VE (L/min) and PetCO2 (mm Hg) were collected continuously at rest and throughout the exercise test. Peak values of oxygen consumption and carbon dioxide production were presented by the highest 30-second average value, obtained during the last stage of the exercise test. Peak respiratory exchange ratio was the highest 30second averaged value between’VO2 and ’VCO2 during the last stage of the test. Resting PetCO2 was the 2-minute averaged value in the seated position prior to exercise, while the peak value was expressed as the highest 30-second average value obtained during the last stage of the exercise test. Ten-second averaged ’VE and VCO2 data, from the initiation of exercise to peak, were used to calculate the ’VE/’VCO2 slope via least squares linear regression. It has been shown to produce clinically optimal information compared with derivations excluding data past the respiratory compensation point [19]. ‘VE/’VCO2 slope was calculated as a linear regression function using 10-s averaged values and excluding the non-linear part of the relationship after the respiratory compensation point (where nonlinear rise in ’VE occurred relative to ’VCO2 in the presence of decrease of end-tidal pressure of CO2. As the study group consisted of COPD patients a dual approach for the measurement of the Anaerobic Threshold (AT) was applied. Both V-slope method and the ventilatory equivalentsmethod for‘VO2 and ’VCO2 were used. The modified Borg scale was applied for peakdyspneaand leg discomfort.

Echocardiography methods: Echocardiography included the generally applied approaches of M-mode, two-dimensional and Doppler echocardiography. Routine structural and haemodynamic indices of both chambers were measured following the guidelines [20,21]. The systolic function of the Left Ventricle (LV) was defined by Simpson’s modified rule.The diastolic function of both ventricles was evaluated by the E/A ratio and the average E/e’ ratio at rest. As a more precise approach for diastolic dysfunction detection, tissue Doppler analysis was used. We used e’ value as the average of medial and the lateral measurements for the mitral annulus. The peak of the average E/e’ ratio>15 was considered as a marker for stress induced Left Ventricular Diastolic Dysfunction (LVDD).

The dimensions of the right ventricle were assessed from thelongaxis parasternal and apical four chamber view [22]. Tricuspid Annular Plane Systolic Excursion (TAPSE) and S-peak velocity were analyzed for RV systolic function evaluation. Right Ventricular Wall Thickness (RVWT) was measured in end-diastole. Systolic pulmonary arterial pressure was calculated by Bernoulli equation and by the Acceleration Time (AT) [22,23]. Right Atrium Volume Index (RAVI) was measured at right ventricle end-systole by Simpson’s modified rule. The peak of the average E/e’ ratio>6 was considered as a marker for stress induced RVDD. Stress induced RV diastolic dysfunction was considered if stress induced E/e’ ratio > 6. All parameters were measured at end-expiration and in triplicate during different heart cycles [23].

Laboratory assays: Approximately 7 mL of venous blood was obtained from all cases. Blood samples were centrifuged immediately after collection and isolated plasma was stored in vials at -80°C until assayed. Resistin was measured by commercial kits, following the procedure protocol. Resistin was determined by an ELISA kit (RayBio_ Human Resistin ELISA Kit Protocol (Cat#:ELH-Resistin-001) The intra- and interassay coefficients of variation in this assay kit ranged from 10 to 12%. Plasma resistin levels were measured in ng/ml.

High Resolution Accurate Mass (HRAM) of 8-isoprostane and prostgalndine E2: Approximately 20 mL of urine was obtained from all cases the levels of 8-isoprostane and prostgalndine E2 in urine samples were determined by HRAM (high resolution accurate mass) mass spectrometry on LTQ Orbitrap® Discovery (ThermoScientific Co, USA) mass spectrometer, equipped with Surveyor® Plus HPLC system and IonMax®electrospray ionization module. The analyses were carried out by stable isotope dilution method in negative ionization mode using HESI II (Heated Electrospray Ionization) source type. The concentration and purification of 8-isoprostane and prostgalndine E2from urine samples was processed by affinity sorbent (Cayman Chemical, USA), following the producer’s protocol with some modification. The urinary 8-isoprostane and prostgalndine E2 levels were standardized to the levels of urinary creatinine. Creatinine was measured applying the enzyme method - Creatinine plus version-2 Cobas Integra (Roche). Results are given in pg/mkmol/ creatinine.

Statistical analysis

Descriptive statistics was used for demographic and clinical data presentation. The Kolmogorov-Smirnov test was used to explore the normality ofdistribution. Continuous variables were expressed as median and interquartile range when data was not normally distributed and with mean ±SD if normal distribution was observed. Categorical variables were presented as proportions. Data were compared between patients with and without RVDD. An unpaired Student’s t test was performed for normally distributed continuous variables. Mann-Whithney-U test was used in other cases. Categorical variables were compared by the Χ2 test or the Fisher exact test. Receiver operating characteristic (ROC) curves were constructed. ROC analysis was performed to test RV echocardiographic parameters at rest that may accurately distinguish between stress RV E/e’ >6 or <6. Regression analysis was also applied with the echocardiographic indices, as qualitative parameters, using their cutoff values. Univariable regression analysis wasperformed to assess which echocardiographic, CPETparameters and biomarkers (resistin, prostglandine E2 and 8-isoprostanes) are associated with stress RV E/e’>6. Multivariable logistic regression analysis by using a forward stepwise approach detected the significant independent predictors of stress RV E/e’>6. Predictive models were constructed. Age, sex, height, weight (BMI), FEV1, ICdyn, were specifically included as covariates.

(In all cases a p value of less than 0.05 was considered significant as determined with SPSS® 13.0 Software (SPSS, Inc, Chicago, Ill) statistics).


Demographic and clinical data

Subjects enrolled in the study were Caucasians at a mean age of 62.50±8.5 years and a body mass index of 27.26±6.92kg/m2. They were divided into two groups - subjects with stress induced right ventricular diastolic dysfunction - 78%(82/104) (COPD-RVDD), and those without stress induced diastolic dysfunction22%(22/104), (COPD -no RVDD). There was no statistically significant difference regarding the demographic and clinical parametersbetween the two groups (Table 1).