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(Chest. 2004;125:1213-1217.)
© 2004 American College of Chest Physicians

Percutaneous Transluminal Mitral Valvuloplasty Reduces Circulating Vascular Cell Adhesion Molecule-1 in Rheumatic Mitral Stenosis*

Mien-Cheng Chen, MD; Hsueh-Wen Chang, PhD; Shyh-Shiann Juang, MS; Hon-Kan Yip, MD; Chiung-Jen Wu, MD; Teng-Hung Yu, MD and Cheng-I Cheng, MD

* From the Division of Cardiology (Drs. Chen, Yip, Wu, Yu, and Cheng), Department of Internal Medicine, Chang Gung Memorial Hospital, Kaohsiung; Department of Biological Sciences (Dr. Chang), National Sun Yat-Sen University, Kaohsiung; and Chia Nan University of Pharmacy and Science (Mr. Juang), Tainan, Taiwan, ROC.

Correspondence to: Mien-Cheng Chen, MD, Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, 123, Ta Pei Rd, Niao Sung Hsiang, Kaohsiung Hsien 83301, Taiwan, ROC; e-mail: chenmien{at}ms76.hinet.net


   Abstract
TOP
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Background: The circulating levels of adhesion molecules, such as vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1), have been demonstrated to be elevated in patients with rheumatic mitral stenosis (MS). However, the impact of percutaneous transluminal mitral valvuloplasty (PTMV) on the elevated circulating levels of VCAM-1 and ICAM-1 in patients with MS has never been investigated.

Methods and results: A total of 19 patients with symptomatic MS undergoing PTMV were studied (group 1) [15 patients in chronic atrial fibrillation, and 4 patients in sinus rhythm]. The plasma levels of soluble VCAM-1 and ICAM-1 in the femoral vein and artery, and right and left atria before PTMV, and those in the peripheral venous blood at the 1-week and 4-week follow-ups after PTMV were determined by solid-phase sandwich enzyme-linked immunosorbent assay. The mitral valve area was calculated by means of the Doppler pressure half-time method. In addition, we measured plasma concentrations of soluble VCAM-1 and ICAM-1 in the peripheral venous blood samples obtained from 22 control patients (including 14 healthy volunteers in sinus rhythm [group 2] and 8 patients in chronic lone atrial fibrillation [group 3]). The plasma level of soluble VCAM-1 was significantly elevated in group 1 patients (1,205.4 ± 462.4 ng/mL [mean ± SD]) compared with group 2 (580.9 ± 208.0 ng/mL) and group 3 patients (716.4 ± 221.6 ng/mL) [p < 0.0001]. In group 1 patients, the plasma levels of soluble VCAM-1 and ICAM-1 in the left atrium did not differ from those in the right atrium, femoral vein, or femoral artery (p = 0.668 for VCAM-1, and p = 0.232 for ICAM-1). The area of mitral valve increased significantly after PTMV (1.08 ± 0.14 cm2 vs 1.48 ± 0.33 cm2, p < 0.0001). The mean left atrial pressure fell significantly after PTMV (22.9 ± 5.2 mm Hg vs 17.7 ± 6.0 mm Hg, p < 0.0001). The peripheral venous plasma level of soluble VCAM-1 obtained before PTMV fell significantly after PTMV (before, 1,205.4 ± 462.4 ng/mL; 1 week after PTMV, 915.7 ± 280.2 ng/mL; 4 weeks after PTMV, 859.0 ± 298.7 ng/mL; p < 0.0001).

Conclusions: In patients with moderate-to-severe MS, the venous plasma level of soluble VCAM-1 fell significantly after PTMV, and the elevated plasma soluble VCAM-1 concentration was associated with hemodynamic abnormality rather than with rheumatic activity.

Key Words: mitral stenosis • mitral valvuloplasty • vascular cell adhesion molecule-1


   Introduction
TOP
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
The circulating levels of adhesion molecules, such as vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1), have been demonstrated to be elevated in patients with rheumatic mitral stenosis (MS).1 Adhesion molecules are expressed on vascular endothelium and on immune and inflammatory cells. Therefore, the increased expression of adhesion molecules in patients with MS may result from inflammatory-induced tissue damage and thus appears to be a marker of the extent of inflammatory disease and endothelial activation. However, Müller and associates2 found marked expression of VCAM-1 not only on inflamed heart valves, but also on larger portions of the degenerative valves with no morphologic evidence of inflammation. Therefore, the elevated circulating VCAM-1 and ICAM-1 in patients with MS might also result from mechanisms other than inflammatory-induced tissue damage. No previous study examines the impact of percutaneous transluminal mitral valvuloplasty (PTMV) on the elevated circulating levels of VCAM-1 and ICAM-1 in patients with MS. Accordingly, we undertook the present study to test the hypothesis that PTMV could reduce the circulating levels of VCAM-1 and ICAM-1 in patients with MS and heart failure, and the elevated plasma soluble VCAM-1 concentration was associated with hemodynamic abnormality rather than with rheumatic activity.


   Materials and Methods
TOP
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Study Population
Nineteen patients who had symptomatic rheumatic MS without significant mitral, tricuspid, or aortic regurgitation and left atrial thrombus and had undergone PTMV were studied (group 1: 2 men and 17 women; age range, 41 to 72 years; mean age, 56.2 ± 11.3 years [± SD]). Fifteen patients had chronic atrial fibrillation, and 4 patients were in sinus rhythm. Six patients had a history of cerebral thromboembolism. Nine patients were in New York Heart Association functional class III, and 10 patients were in New York Heart Association functional class II. No patients had a history of malignancy, inflammatory disease, collage vascular disease, renal or liver disease, diabetes mellitus, hypertension, hyperlipidemia, infectious disease, deep venous thrombosis, pulmonary embolism, or recent surgery.

Peripheral venous plasma levels of VCAM-1 and ICAM-1 were also evaluated in 22 control patients. The group of control patients included 14 healthy volunteers in sinus rhythm (group 2) and 8 patients in chronic lone atrial fibrillation without systemic disease or structural heart disease (group 3). In group 3, two patients had a history of systemic arterial thromboembolism. None of the control patients had a history of active malignancy, inflammatory disease, renal or liver disease, diabetes mellitus, hypertension, hyperlipidemia, deep venous thrombosis, pulmonary embolism, or recent surgery.

Informed consent was obtained from all study subjects. The study protocol was approved by the Institutional Review Committee on Human Research in our institution.

Doppler Echocardiography and Medications
In patients with rheumatic MS, transthoracic echocardiographic examinations were performed on the day of PTMV and before the valvuloplasty procedure with a 2.5-MHz transducer attached to a commercially available echo Doppler machine (Sonos 5500; Hewlett-Packard; Palo Alto, CA) to assess left and right atrial dimensions and mitral valve area. M-mode measurements were performed according to the recommendation of the American Society of Echocardiography. Left and right atrial areas were planimetered in the four-chamber view, and maximum areas were measured (at the end of the T wave on the ECG) and averaged over five beats. The mitral valve area was calculated by means of the Doppler pressure half-time method. The severity of mitral, tricuspid, and aortic insufficiency was determined by Doppler color-flow mapping. The absence of left atrial cavity or appendage thrombus was confirmed by transesophageal echocardiography.

In group 1 patients, digoxin, ß-blockade and Ca-blockade were discontinued for at least five half-lives before study, and therapy with diuretic agents was discontinued on the day of PTMV. Warfarin was discontinued for at least 3 days before PTMV and was administered on the second day after PTMV. Heparin, 5,000 U, was administered into the left atrium after transseptal puncture in each patient. In group 3 patients, therapy with aspirin was discontinued for at least 7 days, digoxin and Ca-blockade were discontinued for at least five half-lives before study, and warfarin was discontinued for at least 3 days before the study.

Valvuloplasty Procedure
PTMV was performed by the transseptal approach with the use of an Inoue balloon catheter (Toray Medical Corporation; Tokyo, Japan). Details of the procedure have been described previously.3 In brief, an Inoue balloon catheter was inserted into the left ventricle via transseptal approach. The distal half of the balloon was inflated in this position, and the balloon was pulled back to the mitral valve orifice. The balloon was then fully inflated and pulled back to the left atrium before being deflated. When additional balloon dilatation was required, the same procedure was repeated. Measurements of left atrial pressure and transmitral pressure gradient were performed immediately before and after valvuloplasty.

Blood Sample Collection and Measurement of Plasma Soluble VCAM-1 and ICAM-1 Concentrations
Blood samples were obtained in the fasting, nonsedative state at 9 to 10 AM in the control and study groups to exclude the possible influence of circadian variations.4 In group 1 patients, blood was obtained from the femoral vein and artery through introducer sheaths immediately after puncture with the patients in the supine position for at least 20 min. Right atrial blood was obtained through the balloon catheter, and left atrial blood was obtained immediately after transseptal puncture before heparin administration. Another set of blood samples from the femoral vein, femoral artery, and right and left atria were obtained at 10 min after optimal PTMV. Five milliliters of blood was drawn into an evacuated tube containing K3 ethylenediamine tetra-acetic acid (Vacutainer; Becton Dickinson; Franklin Lakes, NJ). In group-2 and group-3 subjects, blood was obtained under minimal tourniquet pressure from the antecubital vein using a sterile 22-gauge needle syringe in a single attempt, with the study subjects in the supine position for at least 20 min, and 5 mL of blood was drawn into a container with K3 ethylenediamine tetra-acetic acid (Vacutainer; Becton Dickinson). Blood samples with gross hemolysis were discarded. Mixtures of blood and K3 ethylenediamine tetra-acetic acid were immediately centrifuged (model 5400; Kubota Corporation; Tokyo, Japan) at 3,000 revolutions per minutes for 10 min at room temperature. The plasma was immediately separated and frozen at – 80°C until the assay. Blood samples were also withdrawn for whole blood counts, and biochemical and electrolyte measurements by standard laboratory methods.

The soluble VCAM-1 and ICAM-1 concentrations of human plasma samples were quantified with the use of a commercially available, solid-phase, sandwich enzyme-linked immunosorbent assay kit (Diaclone; Besancon, France). The samples were processed according to the instructions of the manufacturer. The samples, which included standards of known soluble VCAM-1 or ICAM-1 concentrations in buffer and reconstituted extracts of the quality control and test samples and a biotinylated monoclonal antibody specific for VCAM-1 or ICAM-1, were sequentially added to a 96-well microplate precoated with a monoclonal anti-VCAM-1 or anti-ICAM-1 antibody. After 1 h of incubation at room temperature and removal of unbound materials, an enzyme (streptavidin-peroxidase) was added. After incubation and washing to remove all the unbound enzyme, a substrate solution (chromogen [tetramethylbenzidine]) was added to induce a colored reaction product. The reaction product was measured by using a microplate reader (Dynex Technologies; Chantilly, VA) and reading the absorbance at 450 nm with a correction wavelength of 630 nm. A standard curve was determined with the use of the mean absorbance values of the included VCAM-1 and ICAM-1 standards, and the soluble VCAM-1 and ICAM-1 concentrations in all unknown plasma samples were then calculated with linear regression. All standards and samples were tested in duplicate. The minimum detectable dose of soluble VCAM-1 and ICAM-1 are < 0.6 ng/mL and < 0.1 ng/mL, respectively, according to the manufacturer of the assay kits. In our laboratory, the mean interassay coefficients of variance of ICAM-1 and VCAM-1 were 6.2% and 10.3%, respectively and the mean intra-assay coefficients of variance of ICAM-1 and VCAM-1 were 10.7% and 10.1%, respectively.

Statistical Analysis
Continuous variables were described as the mean ± SD. Categorical variables were compared using the Fisher exact test (two tailed). Continuous variables within the same group were compared using paired t test (two tailed). Continuous variables among the three groups were compared using the one-way analysis of variance. A Scheffe test was used for post hoc comparisons. The plasma levels of soluble VCAM-1 and ICAM-1 of the four different sampling sites were compared using repeated-measures analysis of variance. The Scheffe test was used for post hoc comparisons. The correlation between the plasma level of soluble VCAM-1 and plasma level of soluble ICAM-1, mitral valve area, the mean left atrial pressure, or left atrial dimension were performed with the Pearson correlation. Statistical analysis was performed using a statistical software program (SAS for Windows, version 8.02; SAS Institute; Cary, NC); p < 0.05 was considered statistically significant.


   Results
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 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
Baseline Characteristics, Echocardiographic Data, Hemodynamic Variables, and Venous Plasma Levels of Soluble VCAM-1 and ICAM-1 of the Studied Patients
The baseline characteristics for each group are summarized in Table 1 . There were no statistically significant differences among the three groups in terms of the use of ß-blockade, Ca-blockade, amiodarone, propafenone and aspirin, and blood cell counts and biochemistry data. The duration of atrial fibrillation of group 1 patients did not differ from that of group 3 patients. Group 3 patients were significantly older than group 2 patients, and the use of warfarin therapy in patients from groups 1 and 3 was significantly more frequent than that in group 2 patients. The use of digoxin in patients from group 1 was significantly more frequent than that in patients in groups 2 and 3.


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  		Table 1. Baseline Characteristics and Peripheral Venous Plasma VCAM-1 and ICAM-1 Concentrations*

 
In group 1 patients, the left atrial diameter was 47.3 ± 7.0 mm, the mitral valve area was 1.08 ± 0.14 cm2, the prevalvuloplasty left atrial pressure was 22.9 ± 5.2 mm Hg, and the transmitral pressure gradient was 11.3 ± 4.6 mm Hg. All of the patients in group 1 had swirling spontaneous echo contrast only in the left atrium confirmed by transesophageal echocardiography. The area of mitral valve increased significantly after PTMV (1.08 ± 0.14 cm2 vs 1.48 ± 0.33 cm2, p < 0.0001). The mean left atrial pressure fell significantly after PTMV (22.9 ± 5.2 mm Hg vs 17.7 ± 6.0 mm Hg, p < 0.0001). The transmitral pressure gradient fell significantly after PTMV (11.3 ± 4.6 mm Hg vs 7.6 ± 4.3 mm Hg, p = 0.002). The left atrial area reduced after PTMV (35.6 ± 10.7 cm2 vs 32.9 ± 13.4 cm2, p = 0.08), although the difference did not reach statistical significance. There were no significant changes in the right atrial area, left atrial diameter, left ventricular end-systolic and end-diastolic diameters, and ejection fraction after PTMV.

The plasma level of soluble VCAM-1 was significantly elevated in group 1 patients compared with patients in groups 2 and 3 (p < 0.0001) [Table 1]. The plasma level of soluble VCAM-1 among group 3 patients was not significantly higher than that among group 2 patients. The plasma level of soluble ICAM-1 among group 1 patients was not significantly higher than that among group 2 or group 3 patients (Table 1).

Comparison of Plasma Levels of Soluble VCAM-1 and ICAM-1 Among the Four Different Sampling Sites
Analysis of the prevalvuloplasty data of the 19 patients with rheumatic MS revealed that the plasma levels of soluble VCAM-1 and ICAM-1 in the left atrium (1,232.8 ± 612.1 ng/mL and 778.5 ± 311.8 ng/mL, respectively) did not differ from those in the right atrium (1,157.7 ± 477.1 ng/mL and 755.6 ± 334.7 ng/mL, respectively), femoral vein (1,205.4 ± 462.4 ng/mL and 772.6 ± 305.8 ng/mL, respectively), or femoral artery (1,211.5 ± 503.9 ng/mL and 808.3 ± 391.3 ng/mL, respectively) [p = 0.668 for VCAM-1 and p = 0.232 for ICAM-1].

Correlation Between Plasma Levels of Soluble VCAM-1 and ICAM-1 and Hemodynamic and Echocardiographic Variables in Patients With MS
Correlation analysis demonstrated that there was a significantly direct relationship between the venous plasma levels of soluble VCAM-1 and ICAM-1 (p < 0.009; r = 0.584). However, there was no significant correlation between the plasma level of VCAM-1 in the left atrium and left atrial area (p value is not significant [NS]; r = – 0.021), left atrial diameter (p = NS; r = – 0.140), prevalvuloplasty left atrial pressure (p = NS; r = – 0.052), and the severity of MS (p = NS; r = 0.139).

Peripheral Venous Plasma Levels of Soluble VCAM-1 Before and After PTMV
The peripheral venous plasma level of soluble VCAM-1 obtained before PTMV fell significantly after PTMV (before, 1,205.4 ± 462.4 ng/mL; 1 week after, 915.7 ± 280.2 ng/mL; 4 weeks after, 859.0 ± 298.7 ng/mL; p < 0.0001) [Fig 1 ]. The peripheral venous plasma level of soluble VCAM-1 obtained before PTMV did not differ from that obtained at 10 min after PTMV (1,205.4 ± 462.4 ng/mL vs 1,290.2 ± 620.6 ng/mL; p = NS).



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  		Figure 1. The peripheral venous plasma level of soluble VCAM-1 obtained before PTMV (PBb) was significantly higher than that obtained at the 1-week follow-up (PB1w) and at the 4-week follow-up (PB4w) after PTMV. The peripheral venous plasma level of soluble VCAM-1 obtained before PTMV did not differ from that obtained at 10 min after PTMV (PBa). *p = < 0.0001.

 

   Discussion
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
The present study, in which we examined the plasma soluble VCAM-1 and ICAM-1 concentrations in atrial and peripheral venous or arterial blood samples of patients with symptomatic rheumatic MS undergoing PTMV, produced three major findings. First, the venous plasma soluble VCAM-1 level of patients with MS was significantly higher than that of healthy volunteers or patients with lone atrial fibrillation. Our finding confirmed a previous observation.1 Second, in patients with MS, the plasma soluble VCAM-1 and ICAM-1 concentrations in the left atrium did not differ from those in the right atrium, femoral vein, and femoral artery. Finally, as mitral valve area increased significantly and the mean left atrial pressures fell significantly after PTMV, the venous plasma level of soluble VCAM-1 fell significantly at the 1-week and 4-week follow-ups after PTMV.

Mechanisms of Reducing Plasma Soluble VCAM-1 Concentration by PTMV
In this study, we demonstrated that venous plasma level of soluble VCAM-1 fell significantly at the 1-week follow-up after PTMV. There were several mechanisms that contributed to this observation. First, the plasma soluble VCAM-1 level decreased by mechanical balloon dilatation of the mitral valve, which significantly increased mitral valve area and significantly reduced left atrial pressure, but supposedly did not affect rheumatic activity. We concluded that the elevated plasma soluble VCAM-1 concentration was associated with hemodynamic abnormality rather than with rheumatic activity. Second, it has been demonstrated that there is a relationship between VCAM-1 messenger RNA expression and the concentration of soluble VCAM-1 in patients with aortic and thoracic disease.5 It is possible that the increased shear stress on the endothelium of a stenotic valve with abnormal blood flow or "jet lesion" in the downstream may result in increased expression and/or shedding of VCAM-1. Therefore, it is reasonable to observe that mechanical balloon dilatation of the mitral valve, which significantly increased mitral valve area and improved blood flow status, significantly reduced the plasma level of soluble VCAM-1 in patients with MS.

Study Limitations
There were several limitations in this study. First, the plasma level of soluble ICAM-1 among group 1 patients was not significantly higher than that among group-2 or group-3 patients. This could be due to a type II error, as correlation analysis demonstrated that there was a significantly direct relationship between the venous plasma levels of soluble VCAM-1 and ICAM-1. Second, in our study, we demonstrated that the plasma levels of soluble VCAM-1 and ICAM-1 among patients with lone atrial fibrillation did not differ from those of healthy volunteers. Our results should be viewed as preliminary and await confirmation by larger clinical study. Third, the plasma half-life of soluble VCAM-1 remains unknown. In our study, the venous plasma level of soluble VCAM-1 obtained before PTMV did not differ from that obtained at 10 min after PTMV. However, venous plasma level of soluble VCAM-1 fell significantly at the 1-week follow-up after PTMV. Therefore, the plasma half-life of soluble VCAM-1 must be > 10 min. Finally, as the number of patients having a history of systemic arterial thromboembolism was small, it was not our aim to study the difference in the plasma levels of soluble VCAM-1 and ICAM-1 between patients with and without a history of systemic arterial thromboembolism. In conclusion, in patients with moderate-to-severe MS, the venous plasma level of soluble VCAM-1 fell significantly after PTMV, and the elevated plasmasoluble VCAM-1 concentration was associated with hemodynamic abnormality rather than with rheumatic activity.


   Acknowledgements
 
We thank Ms. Hsiu-Chin Tsai for technical assistance.


   Footnotes
 
Abbreviations: ICAM-1 = intercellular adhesion molecule-1; MS = mitral stenosis; NS = not significant; PTMV = percutaneous transluminal mitral valvuloplasty; VCAM-1 = vascular cell adhesion molecule-1

This study was supported by a grant from Chang Gung Memorial Hospital, Chang Gung University (No. CMRP1139).

Received for publication May 30, 2003. Accepted for publication September 25, 2003.


   References
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Yetkin, E, Erbay, AR, Ileri, M, et al (2001) Levels of circulating adhesion molecules in rheumatic mitral stenosis. Am J Cardiol 88,1209-1211[CrossRef][ISI][Medline]
  2. Müller, AM, Cronen, C, Kupferwasser, LI, et al Expression of endothelial cell adhesion molecules on heart valves: up-regulation in degeneration as well as acute endocarditis. J Pathol 2000;191,54-60[CrossRef][ISI][Medline]
  3. Hung, JS, Chern, MS, Wu, JJ, et al Short- and long-term results of catheter balloon percutaneous transvenous mitral commissurotomy. Am J Cardiol 1991;67,854-862[CrossRef][ISI][Medline]
  4. Angleton, P, Chandler, WL, Schmer, G Diurnal variation of tissue-type plasminogen activator and its rapid inhibitor (PAI-1). Circulation 1989;79,101-106[ISI][Medline]
  5. Nakai, K, Itoh, C, Kawazoe, K, et al Concentration of soluble vascular cell adhesion molecule-1 (VCAM-1) correlated with expression of VCAM-1 mRNA in the human atherosclerotic aorta. Coron Artery Dis 1995;6,497-502[ISI][Medline]



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