Right ventricular function at rest and during exercise in chronic obstructive pulmonary disease. Comparison of two radionuclide techniques

Cardiovascular and respiratory dysfunction in chronic obstructive pulmonary disease complicated by impaired peripheral oxygenation

Background

Impaired peripheral oxygenation (IPO)-related variables readily achieved with cardiopulmonary exercise testing (CPET) represent cardiovascular dysfunction. These variables include peak oxygen uptake ( (V˙O2)<85% predicted, anaerobic threshold <40%V˙O2max predicted, V˙O2-work rate slope <8.6 mL/watt, oxygen pulse <80% predicted, and ventilatory equivalents for O₂ and CO₂ at nadir of >31 and >34, respectively. Some of these six variables may be normal while the others are abnormal in patients with chronic obstructive pulmonary disease (COPD). This may result in confusion when using the interpretation algorithm for diagnostic purposes. We therefore hypothesized that patients found to have abnormal values for all six variables would have worse cardiovascular function than patients with abnormal values for none or some of these variables.

Methods

In this cross-sectional comparative study, 58 COPD patients attending a university teaching hospital underwent symptom-limited CPET with multiple lactate measurements. Patients with abnormal values in all six IPO-related variables were assigned to an IPO group while those who did not meet the requirements for the IPO group were assigned to a non-IPO group. Cardiovascular function was measured by two-dimensional echocardiography and Δlactate/ΔV˙O2, and respiratory dynamics were compared between the two groups.

Results

Fourteen IPO and 43 non-IPO patients were entered into the study. Both groups were similar with regard to left ventricular ejection fraction and right ventricular morphology (P>0.05 for both). At peak exercise, both groups reached a similar heart rate level and Δlactate/ΔV˙O2. The IPO patients had an unfavorable dead space to tidal volume ratio, mean inspiratory tidal flow, and shallow breathing (P<0.05–P<0.001).

Conclusion

Our IPO and non-IPO patients with COPD had similar cardiovascular performance at rest and at peak exercise, indicating that IPO variables are non-specific for cardiovascular function in these patients. COPD patients with full IPO variables have more deranged ventilatory function.

Right ventricular ejection fraction during exercise as a predictor of mortality in patients awaiting lung transplantation: a cohort study

OBJECTIVE

The occurrence of right ventricular dysfunction is a well-known indicator of poor prognosis in patients with chronic cardiopulmonary disease. The role of right ventricular ejection fraction (RVEF) at rest and during exercise as predictors of outcome in patients awaiting lung transplantation (LTx) is unclear.

DESIGN

We performed a retrospective analysis of lung transplant candidates who had undergone equilibrium radionuclide angiography (ERNA), to determine baseline and exercise RVEF. Lung function, gas exchange and pulmonary haemodynamics were also assessed.

PATIENTS AND MAIN OUTCOME MEASURES

152 patients (mean age 47±11 years; 59% women) were included in the study. Primary endpoint was death on the waiting list for LTx. Main diagnoses were α-1 antitrypsin deficiency (n=35), chronic obstructive pulmonary disease (n=41), cystic fibrosis (n=10), interstitial lung disease (n=34) and pulmonary arterial hypertension (n=32). Twenty-five patients died (16, 4%). LTx was performed in 121 patients. The mean RVEF at rest was equal to mean RVEF during exercise (38±12%). In univariate analysis RVEF at rest, RVEF during exercise, heart rate and forced volume capacity (FVC) % of predicted were factors significantly associated with risk of death. In multivariate analysis RVEF during exercise and FVC% of predicted were independent predictors of death.

CONCLUSIONS

In lung transplant candidates, right ventricular function during exercise is a stronger predictor of outcome than right ventricular function at rest. RVEF during exercise assessed by ERNA could be incorporated into priority-based allocation algorithms for LTx.

Assessment of the right ventricular function in patients with chronic obstructive pulmonary disease using MRI

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is often associated with changes of the structure and the function of the right ventricle (RV). Therefore, the assessment of right ventricular function and myocardial mass (MM) is clinically important for the evaluation of the severity of COPD, which may provide an objective basis for therapeutic strategy.

PURPOSE

To assess the right ventricular function and RV MM in patients with mild to severe COPD using magnetic resonance imaging (MRI).

MATERIAL AND METHODS

We prospectively studied 49 COPD patients determined by the pulmonary function test (PFT). Using the Global Initiative for COPD classification, the COPD patients were divided into three groups according to the severity of the disease: group I = mild (n = 18); group II = moderate (n = 16); and group III = severe (n = 15). The patient groups were compared to a control group consisting of 30 age-matched, healthy, non-smoking subjects. The RV function and RV MM were obtained by 1.5T cardiac MRI in all of the four groups. The results were compared among the four groups using the ANOVA. Pearson's correlation was used to evaluate the relationship between the right ventricular ejection fraction (RVEF) and MM with the PFT results in COPD patients.

RESULTS

The RVEF was significantly lower in group III than in the other groups (P < 0.01). The RV MM differed significantly among all groups (P < 0.01) and gradually increased with the severity of COPD (P < 0.01). The correlation was significant between the MRI results and forced expiratory volume in 1 s (r = 0.860 for RVEF, r = -0.838 for RV MM) in COPD patients.

CONCLUSION

The RVEF and RV MM measured by MRI correlate significantly with the severity of disease as determined by PFT in patients with COPD.

Impact of pulmonary artery pressure on exercise function in severe COPD

BACKGROUND

Although pulmonary hypertension commonly complicates COPD, the functional consequences of increased pulmonary artery pressures in patients with this condition remain poorly defined.

METHODS

We conducted a cross-sectional analysis of a cohort of 362 patients with severe COPD who were evaluated for lung transplantation. Patients with pulmonary hemodynamics measured by cardiac catheterization and available 6-min walk test results were included. The association of mean pulmonary artery pressure (mPAP) with pulmonary function, echocardiographic variables, and 6-min walk distance was assessed.

RESULTS

The prevalence of pulmonary hypertension (mPAP, > 25 mm Hg; pulmonary artery occlusion pressure [PAOP], < 16 mm Hg) was 23% (95% confidence interval, 19 to 27%). In bivariate analysis, higher mPAP was associated with lower FVC and FEV(1), higher Pco(2) and lower Po(2) in arterial blood, and more right heart dysfunction. Multivariate analysis demonstrated that higher mPAP was associated with shorter distance walked in 6 min, even after adjustment for age, gender, race, height, weight, FEV(1), and PAOP (-11 m for every 5 mm Hg rise in mPAP; 95% confidence interval, -21 to -0.7; p = 0.04).

CONCLUSIONS

Higher pulmonary artery pressures are associated with reduced exercise function in patients with severe COPD, even after controlling for demographics, anthropomorphics, severity of airflow obstruction, and PAOP. Whether treatments aimed at lowering pulmonary artery pressures may improve clinical outcomes in COPD, however, remains unknown.

Assessment of the right ventricular function and mass using cardiac multi-detector computed tomography in patients with chronic obstructive pulmonary disease

Objective

We wanted to assess the relationship between measurements of the right ventricular (RV) function and mass, with using cardiac multi-detector computed tomography (MDCT) and the severity of chronic obstructive pulmonary disease (COPD) as determined by the pulmonary function test (PFT).

Materials and Methods

Measurements of PFT and cardiac MDCT were obtained in 33 COPD patients. Using the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification, the patients were divided into three groups according to the severity of the disease: stage I (mild, n = 4), stage II (moderate, n = 15) and stage III (severe, n = 14). The RV function and the wall mass were obtained by cardiac MDCT. The results were compared among the groups using the Student-Newman-Keuls method. Pearson's correlation was used to evaluate the relationship between the right ventricular ejection fraction (RVEF) and the wall mass results with the PFT results. P-values less than 0.05 were considered statistically significant.

Results

The RVEF and mass were 47±3% and 41±2 g in stage I, 46±6% and 46±5 g in stage II, and 35±5% and 55±6 g in stage III, respectively. The RVEF was significantly lower in stage III than in stage I and II (p < 0.01). The RV mass was significantly different among the three stages, according to the disease severity of COPD (p < 0.05). The correlation was excellent between the MDCT results and forced expiratory volume in 1 sec (r = 0.797 for RVEF and r = -0.769 for RV mass) and forced expiratory volume in 1 sec to the forced vital capacity (r = 0.745 for RVEF and r = -0.718 for RV mass).

Conclusion

Our study shows that the mean RV wall mass as measured by cardiac MDCT correlates well with the COPD disease severity as determined by PFT.

Early changes of cardiac structure and function in COPD patients with mild hypoxemia

BACKGROUND

COPD is often associated with changes of the structure and the function of the heart. Although functional abnormalities of the right ventricle (RV) have been well described in COPD patients with severe hypoxemia, little is known about these changes in patients with normoxia and mild hypoxemia.

STUDY OBJECTIVES

To assess the structural and functional cardiac changes in COPD patients with normal Pa(O2) and without signs of RV failure.

METHODS

In 25 clinically stable COPD patients (FEV1, 1.23 +/- 0.51 L/s; Pa(O2), 82 +/- 10 mm Hg [mean +/- SD]) and 26 age-matched control subjects, the RV and left ventricular (LV) structure and function were measured by MRI. Pulmonary artery pressure (PAP) was estimated from right pulmonary artery distensibility.

RESULTS

RV mass divided by RV end-diastolic volume as a measure of RV adaptation was 0.72 +/- 0.18 g/mL in the COPD group and 0.41 +/- 0.09 g/mL in the control group (p < 0.01). LV and RV ejection fractions were 62 +/- 14% and 53 +/- 12% in the COPD patients, and 68 +/- 11% and 53 +/- 7% in the control subjects, respectively. PAP estimated from right pulmonary artery distensibility was not elevated in the COPD group.

CONCLUSION

From these results, we conclude that concentric RV hypertrophy is the earliest sign of RV pressure overload in patients with COPD. This structural adaptation of the heart does not alter RV and LV systolic function.

Intermittent Exercise Test in Chronic Obstructive Pulmonary Disease Patients: How Do the Pulmonary Hemodynamics Adapt?

PURPOSE

Endurance training is an important component of rehabilitation in patients with chronic obstructive pulmonary disease (COPD). In our study, we investigated the pulmonary hemodynamics' adaptation during a high-intensity intermittent exercise in such patients.

METHODS

Eight patients underwent a 30-min exercise, alternating a 4-min work set at their first ventilatory threshold with a 1-min exercise set at 90% of their maximal tolerated power output. Pulmonary arterial pressure was measured by means of a right heart catheter. Cardiac output was calculated using the Fick's principle applied to oxygen.

RESULTS

VO(2), cardiac output, and ventilation increased during the first minutes of exercise and remained stable thereafter. Heart rate increased significantly and progressively to its maximal value from rest to the end of the test (P < 0.001). After an initial increase, stroke volume decreased significantly (P < 0.05). Pulmonary arterial pressure increased from rest (mean +/- SEM 23.9 +/- 2.1 mm Hg) to the fifth minute of exercise (41.6 +/- 2.8 mm Hg), and decreased significantly thereafter (35.2 +/- 3.3 mm Hg at the 30th minute) (P < 0.001). Total pulmonary vascular resistance decreased from rest to the end of the test (P < 0.001).

CONCLUSION

The high-intensity 1-min bouts of work of our intermittent work exercise are well tolerated without pushing the pulmonary arterial pressure dramatically high in COPD patients.

New method for calculating right ventricular ejection fraction using gated myocardial perfusion studies

BACKGROUND

Quantification of right ventricular ejection fraction (RVEF) is important in patients who have right heart failure or cor pulmonale. When Tl-201 was the primary radiotracer used to evaluate myocardial perfusion, the outline of the right ventricle could vary and was not visualized in most patients. However, visualization of the right ventricle has become easier with the use of Tc-99m-labeled myocardial perfusion agents.

PURPOSE

This study describes a new method for quantifying RVEF using gated stress myocardial perfusion (GMP) slices. The results are compared with those of first-pass radionuclide ventriculography (FPRNA) in the same patients.

METHODS

Fifty-two consecutive patients referred for routine GMP imaging were included. After administration of Tc-99m tetrofosmin, all patients underwent FPRNA using a single crystal gamma camera and a GMP study. Regions of interest (ROI) were drawn to outline the right ventricular cavity at end diastole and end systole from three pairs of GMP slices. The RVEF was calculated from the number of pixels within the ROIs. The mean RVEF obtained using FPRNA and GMP imaging was 51.8 +/- 10.8% and 51.9 +/- 12.3%, respectively. The two methods showed good correlation with r = 0.81. In addition, there was no significant difference in the RVEFs calculated using these methods (P = 0.85). Bland-Altman analysis also showed good agreement between the two methods (limits of agreement +14.4% to -14.0%, slope = 0.19). Intraobserver and interobserver correlation were evaluated by reanalyzing 12 patients using the new RVEF quantification method and were good at r = 0.87 and 0.82, respectively. Therefore, this is a new convenient method for evaluating RVEF as part of a routine tomographic gated myocardial perfusion study.

Suppressive effect of sarpogrelate hydrochloride on respiratory failure and right ventricular failure with pulmonary hypertension in patients with systemic sclerosis

We evaluated the effect of 12 months of 300-mg oral sarpogrelate hydrochloride (SH) once daily on the symptoms of Raynaud's phenomenon, respiratory failure and cardiac function in seven patients with systemic sclerosis. Arterial blood gases, pulmonary function, mean pulmonary arterial pressure, left ventricular ejection fraction (LVEF), right ventricular ejection fraction (RVEF), white blood cell count, C-reactive protein and the plasma concentrations of fibrinopeptide A, beta-thromboglobulin, platelet factor 4 and thrombomodulin were evaluated before and 2 and 12 months after SH administration. After 2 and 12 months of SH administration, a significant decrease was found in the frequency and duration of Raynaud's phenomenon, as well as the coldness, numbness and pain of Raynaud's phenomenon. Respiratory failure, as estimated by Hugh-Jones classification, was significantly decreased, whereas the percentage carbon monoxide diffusion capacity was significantly increased. The mean pulmonary arterial pressure decreased significantly, as did plasma fibrinopeptide A, beta-thromboglobulin and platelet factor 4. There was no significant change in LVEF after 2 or 12 months, but after 12 months of SH administration, RVEF increased significantly. In conclusion, use of SH may prevent Raynaud's phenomenon, respiratory failure and right ventricular failure in patients with systemic sclerosis.

Radiofrequency catheter modification of atrioventricular junction in patients with COPD and medically refractory multifocal atrial tachycardia

BACKGROUND

Multifocal atrial tachycardia (MAT) is a difficult clinical problem generally associated with acute cardiorespiratory illness. The purpose of this study was to assess the feasibility and clinical usefulness of atrioventricular (AV) junction modification as a nonpharmacologic therapy for medically refractory MAT.

METHODS AND RESULTS

Thirteen patients with COPD and medically refractory MAT underwent AV junction modification. Complications and outcome of this procedure were monitored. Subjective perceptions of quality of life assessed by a semiquantitative questionnaire and cardiac performance study were obtained before ablation (baseline) and 1 and 6 months after ablation. Radiofrequency energy was applied until the average ventricular rate fell to < 100 beats/min. Ablation procedures controlled the ventricular response in 11 of 13 patients (84%). One patient had unsuccessful modification. Another patient developed delayed complete AV block on the second day after ablation. In these 13 patients, average ventricular rate was reduced from a mean of 145 +/- 11 to 89 +/- 22 beats/min immediately after the ablation (p < 0.01). One patient had recurrent symptomatic MAT at 1 month after ablation; this patient underwent a second procedure without late recurrence. All patients were followed up for at least 6 months (mean, 11 +/- 5 months; range, 6 to 18 months). General quality of life and frequency of significant symptoms improved significantly in patients with successful modification at 1 and 6 months. The left ventricular ejection fraction increased significantly after ablation (44.5 +/- 7.3% at baseline, 49.4 +/- 4. 2% at 1 month, and 50.0 +/- 4.9% at 6 months; all p < 0.05). However, right ventricular ejection fraction remained unchanged (34.7 +/- 6. 2% at baseline, 35.7 +/- 4.4% at 1 month, and 34.3 +/- 4.6% at 6 months; all p > 0.05). The consumption of health-care resources (including frequency of hospital admission and emergency department attendance, antiarrhythmic drug trials) decreased significantly 6 months after AV junction modification. Pulmonary function and theophylline level remained unchanged during follow-up.

CONCLUSIONS

AV junction modification offers an effective therapy for controlling ventricular rate in medically refractory MAT. This procedure improves the quality of life and left ventricular function in selected patients with symptomatic and medically refractory MAT.

Simultaneous assessment of right ventricular function and hypertrophy by Tc-99m MIBI

PURPOSE

Tc-99m MIBI allows the simultaneous performance of cardiac blood pool scintigraphy and myocardial SPECT. The authors performed studies to determine whether right ventricular function and hypertrophy can be evaluated simultaneously using Tc-99m MIBI in patients with right heart disease.

METHODS

Using right heart catheterization, several parameters of pulmonary circulation were measured, including right ventricular ejection fraction, in 23 patients with chronic pulmonary disease and pulmonary vascular disease. Within 1 week, right heart blood pool scintigraphy was performed using the first-pass method using Tc-99m MIBI. The right ventricular ejection fraction calculated from right heart blood pool scintigraphy was compared with that measured using right heart catheterization. Myocardial SPECT was performed 1 hour after right heart blood pool scintigraphy. On the short axis images, which allowed optimal visualization of the right ventricle, the right and left ventricular free walls were established as regions of interest. Myocardial wall counts were determined. The right ventricular uptake: left ventricular uptake ratio was calculated to study the relation of that ratio to mean pulmonary artery pressure and total pulmonary resistance.

RESULTS

A significant correlation was observed between the right ventricular ejection fraction calculated on right heart catheterization and that calculated on right heart blood pool scintigraphy. The right ventricular uptake:left ventricular uptake ratio correlated positively with pulmonary artery pressure and total pulmonary resistance.

CONCLUSION

These results suggest that Tc-99m MIBI allows simultaneous noninvasive evaluation of cardiac function and structure, which previously was considered impossible in patients with right heart disease.

MRI evaluation of right ventricular pressure overload in chronic obstructive pulmonary disease

In chronic obstructive pulmonary disease (COPD), the development of pulmonary hypertension is common. This study was performed to assess the signs of right ventricular (RV) pressure overload and RV failure in COPD. In 8 COPD patients without primary cardiac disease, RV wall thickness, mass, and end-diastolic volume were measured by cardiac-triggered cine MRI. MR phase-contrast velocity quantification was used to measure stroke volume and the patterns of flow into and out of the RV. Data of patients were tested versus those of a control group matched for age (n = 8). Results showed that the RV wall thickness was increased (.6 +/- 0.1 vs 0.4 +/- 0.1 cm, P < .001). RV mass was increased (67 +/- 11 vs 57 +/- 5 g, P < .005). RV stroke volume was decreased (57 +/- 13 vs 71 +/- 13 ml, P < .01), but RV ejection fraction was not different. In the main pulmonary artery flow, the quotient of acceleration time divided by ejection time was decreased (33 +/- 5% vs 38 +/- 4%, P < .05), which is indicative of pulmonary hypertension. In conclusion, this MRI protocol provides a tool to assess the effects of RV pressure overload in COPD before heart failure has become manifest.

The effect of right ventricular hypertrophy on left ventricular ejection fraction in pulmonary emphysema

STUDY OBJECTIVE

The development of right ventricular (RV) hypertrophy in emphysema is accompanied by involvement of the left ventricle (LV) and its systolic function. Our objective was to study the relation between RV hypertrophy and LV ejection fraction in emphysema by means of MRI.

PATIENTS

Ten emphysematous patients (FEV1, 0.99+/-0.32 L; FEV1/vital capacity (VC), 0.32+/-0.11 [mean+/-SD]) and 10 age-matched control subjects were included. Exclusion criteria were any history of systemic hypertension, ischemic or valvular heart disease, or episodes of right- and/or left-sided cardiac failure.

MEASUREMENTS AND RESULTS

Rapid scout imaging was used to measure RV and LV wall mass, wall thickness, and end-diastolic volume. Stroke volume was derived from the main pulmonary artery flow. RV wall volume, RV wall thickness, and the ratio of RV to LV wall thickness were significantly larger in the patient group than in the control group (p<0.01). Furthermore, patients had significantly lower values of LV ejection fraction (p<0.01) than the control subjects. A flattening or leftward displacement of the ventricular septum during systole was observed. In addition, our study showed an increase of LV ejection fraction proportional with the RV wall thickness (r=0.78, p<0.01) in severely emphysematous patients.

CONCLUSION

These data are in support of the hypothesis that flattening of the interventricular septum explains the relatively normal LV ejection fraction in emphysematous patients with severe RV hypertrophy.

Assessment of right ventricle function and pulmonary artery circulation by cine-MRI in patients with AIDS

OBJECTIVE

To evaluate right ventricle (RV) anatomy and performance and its relationships with pulmonary circulation in AIDS patients.

DESIGN

We conducted a prospective blinded study by using cine-MRI, a well-accepted method to assess RV and pulmonary circulation.

SETTING

A university hospital.

PARTICIPANTS

Ten healthy volunteers and 13 asymptomatic AIDS patients.

MEASUREMENTS

RV end-diastolic and end-systolic volumes, RV ejection fraction (RVEF), pulmonary artery (PA) diameter, main pulmonary artery distensibility (MPAD), RV free wall diastolic thickness (RVWT), and RV mass were measured. The RVWT/left ventricular wall thickness index was calculated.

RESULTS

AIDS patients had significantly increased RV end-diastolic and end-systolic volumes and decreased RVEF (50 +/- 10 vs 59 +/- 6; p < 0.03). Four AIDS patients had RV wall motion abnormalities; 5 (38%) had an RVEF under 45%. RVWT, the RVWT/left ventricular wall thickness index, and PA diameter were significantly increased in AIDS patients. RV mass was increased in 54% of AIDS patients. MPAD was significantly lower in AIDS patients (18.8 +/- 15 vs 26 +/- 4; p < 0.01). A significant relationship was found between RV mass and MPAD (r = 0.76; p = 0.02).

CONCLUSIONS

RV function is frequently impaired in AIDS patients. Anatomic and functional abnormalities found in RV and PA parameters suggest a systolic overload on RV. Pulmonary circulation abnormalities may influence RV structure and function in AIDS patients.