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Ann Thorac Surg 2007;84:510-513
© 2007 The Society of Thoracic Surgeons

Original Articles: Cardiovascular

No Additive Effect of Passive Containment Surgery in Patients With Aortic Regurgitation and Left Ventricular Dilation

Fredrik Bredin, MD*, Arne Olsson, MD, Anders Franco-Cereceda, MD, PhD

Section of Cardiothoracic Surgery and Anaesthesiology, Institution of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden

Accepted for publication April 2, 2007.

* Address correspondence to Dr Bredin, Department of Cardiothoracic Surgery and Anaesthesiology, Karolinska University Hospital, Stockholm, S-171 76, Sweden (Email: fredrik.bredin{at}karolinska.se).


   Abstract
Top
 Abstract
Introduction
 Material and Methods
 Results
 Comment
 Acknowledgments
 References
 
Background: After valve replacement in patients with aortic regurgitation short-term and long-term improvement of left ventricular function are related to early reduction of left ventricular dilatation. This case-control study was conducted to investigate the potential beneficial effects by concomitant application of the Acorn Cor Cap Cardiac Support Device (Acorn Cardiovascular Inc, St. Paul, MN) on reduction of ventricular dilatation in patients with aortic regurgitation and advanced ventricular dilatation undergoing aortic valve replacement.

Methods: Of ten patients with longstanding aortic regurgitation and ventricular dilatation subjected to aortic valve replacement using mechanical valve prostheses, five were in addition subjected to application of the Cardiac Support Device (Acorn). Cardiac function and dimensions were measured by echocardiography preoperatively and 3 and 12 months postoperatively.

Results: After aortic valve replacement, there was a rapid and sustained decrease in end-diastolic and end-systolic diameters (before operation 72 ± 4 and 54 ± 8 mm, to 54 ± 10 and 40 + 11 mm at 3 months; and 53 ± 9 and 35 ± 6 mm, 12 months after operation). This did not differ after Cardiac Support Device (Acorn) application (before operation 74 ± 1 and 56 ± 5 mm; 52 ± 8 and 39 ± 9 mm, 3 months after operation; and 54 ± 6 and 39 ± 8 mm, at 12 months). The left ventricular ejection fraction remained unchanged in both groups.

Conclusions: Application of the Acorn Cor Cap Cardiac Support Device in patients with aortic regurgitation and severe ventricular dilatation does not influence reverse remodeling or cardiac function compared with aortic valve replacement alone.


   Introduction
Top
 Abstract
 Introduction
Material and Methods
 Results
 Comment
 Acknowledgments
 References
 
Aortic valve replacement (AVR) is indicated in the absolute majority of patients with symptomatic aortic regurgitation (AR). Patients with AR and left ventricular (LV) dysfunction or severe LV dilatation should be evaluated for AVR even if they are asymptomatic because it has been shown that the majority of these patients will rapidly develop symptoms [1]. Moreover, patients under conservative management with AR and LV dilatation are at high risk for cardiac events irrespective of the presence or absence of symptoms [2]. In patients with AR undergoing AVR there is a correlation between early reduction of LV dilatation and improvement of LV systolic function [3]. Furthermore, lack of reversed remodeling after AVR is associated with poor prognosis (see reference 3).

The Acorn Cor Cap Cardiac Support Device (CSD; Acorn Cardiovascular Inc, St Paul, MN) is a mesh-like polyester fabric with bidirectional compliance. It has been developed primarily to be positioned around the failing heart in order to reduce wall stress and reshape the heart from a dilated spherical shape to an ellipsoidal shape, thus facilitating a reversed remodeling of the heart [4]. The safety and efficacy of mitral valve surgery with and without concomitant application of the CSD in patients with heart failure has recently been evaluated and proven in the Acorn clinical trial [5].

We have earlier presented a case describing the early effect of AVR combined with CSD surgery. Postoperative follow-up showed a decrease in LV end systolic diameter (LVESD) and LV end diastolic diameter (LVEDD) suggesting that addition of passive containment surgery may prove beneficial when combined with AVR in severe AR and LV dilatation [6].

The aim of the present case-control study was, therefore, to evaluate further the potential beneficial role for the CSD combined with AVR in patients with longstanding AR and ventricular dilatation by echocardiographic measurements of cardiac dimension and function. Patients subjected to AVR and application of the CSD were evaluated with echocardiographic tissue velocity imaging (TVI). In addition, circulating plasma levels of endothelin-1 (ET-1) and it’s precursor big endothelin-1 (big ET-1) have been measured in the patients subjected to AVR and application of the CSD because it earlier was shown that in dilated cardiomyopathy patients the use of the CSD combined with additional surgical interventions (ie, coronary artery by pass grafting [CABG] or mitral valve annuloplasty) there is a correlation between reduction of LV dimension and decreased plasma levels of ET-1 [7].


   Material and Methods
Top
 Abstract
 Introduction
 Material and Methods
Results
 Comment
 Acknowledgments
 References
 
Between April 2003 and March 2006, ten male patients with AR graded as 3-4/4, ventricular dilatation with LVEDD greater than 70 mm, and normal coronary angiograms were accepted for AVR. The first five consecutive patients were asked and accepted to participate in a pilot study evaluating the effects of CSD application in addition to a mechanical valve prosthesis. Five consecutive patients undergoing AVR without device implantation served as controls. The study was approved by the local ethics committee at the Karolinska Hospital and written consent was obtained from all patients.

The patient preoperative characteristics are presented in Table 1 and their cardiac medications throughout the study period are presented in Table 2. Anesthesia was induced using fentanyl (5 to 10 µg/kg), midazolam (0.02 to 0.04 mg/kg), and propofol (0.05 to 1.5 mg/kg). Intubation was facilitated with atracrium (0.1 mg/kg). Anesthesia was maintained with intermittent fentanyl and sevorane precardio pulmonary bypass (CPB) and an infusion of propofol (1 to 4 mg/kg/hour) during and after CPB.


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  		Table 1 Preoperative Characteristics of Patients
 

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  		Table 2 Cardiac Medications of Patients Throughout the Study Period
 
All patients were operated on by the same surgeon through a midline sternotomy using CPB with a centrifugal pump (BP80; Biomedicus Biomed, Houston, TX) and a membrane oxygenator (Affinity, Medtronic Inc, Minneapolis, MN) primed with Ringers solution. During CPB the temperature was allowed to drift to 35°C. Cardiac arrest was achieved with a cardioplegia solution mixed 1:4 with blood and delivered at a temperature of 4°C. The cardioplegia contained potassium chloride 100 mmol, magnesium sulfate, glucose 28 mmol, tris(hydroxymethyl)aminomethane 20 mmol, and saline 0.9% to a volume of 1,000 mL. The perioperative characteristics of the patients are presented in Table 3.


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  		Table 3 Perioperative Characteristics of Patients
 
Before applying the CSD, after opening the chest and pericardium but before commencing CPB, the heart size was measured apex to base and circumference to select proper sizing and the device was stabilized by interrupted 3-0 Prolene sutures (Ethicon, Somerville, NJ). Final adjustment was done on the fully beating heart to ensure a snug fit.

After removal of the native valve, all patients received a mechanical aortic valve prosthesis (Carbomedics, 25 to 29 mm; Carbomedics Inc, Austin, TX). The postoperative cause was uneventful.

Prior to surgery, 3 and 12 months postoperatively, all patients were evaluated by transthoracic echocardiography (System 5; GE Vingmed, Hortem, Norway), patients subjected to CSD application were in addition examined with TVI. All examinations, with the subjects in left lateral decubitus position, were performed in an unblinded manner by the same physician. The left ventricular cavity size was measured at end-diastole and end-systole; ejection fraction (EF) was calculated using the modified Simpson’s rule. Using TVI, mitral and tricuspid annular velocities were recorded. Mitral annular velocities were recorded at six sites corresponding to the septal, lateral, anterior, inferior, anteroseptal, and inferolateral LV wall. Tricuspid annular velocities were recorded at the free RV wall. The online analysis included measurements of peak systolic annular velocities (Sm), early diastolic (Em), and late diastolic (Am) annular velocities. Global LV and right ventricle (RV) systolic and diastolic function were estimated using a mean value of these mitral and tricuspid annular velocities.

Plasma for analysis of ET-1 and big ET-1 was obtained from a peripheral vein before surgery and at patient follow-up 12 months postoperatively. The samples were collected into ethylenediaminetetraacetic acid vacuum tubes from nonfasting patients in the afternoon, kept in ice slush, and centrifuged. The plasma was then frozen at –70°C and stored until analysis. The content of ET-1 and big ET-1 like immunoreactivity was determined by radioimmunoassay using commercially available antisera as described earlier [7].

Statistical Analysis
Data are presented as mean ± standard deviation. A p less than 0.05 was considered significant. Data were analyzed according to a repeated measures analysis of variance, with time (from preoperative values to 12 months postoperatively) as the repeated measures factor and CSD (yes-no) as the between factor.


   Results
Top
 Abstract
 Introduction
 Material and Methods
 Results
Comment
 Acknowledgments
 References
 
All patients survived the surgical procedure and could leave the hospital after an average hospital stay of 10 ± 1 days. The postoperative follow-up at 3 and 12 months is complete.

Echocardiographic Examinations
Echocardiographic examinations showed significant and sustained reductions in cardiac dimensions measured as LVEDD and LVESD. The LVEDD decreased from 74 ± 1 mm and 72 ± 4 mm preoperatively to 54 ± 6 mm and 53 ± 9 mm at 12 months postoperatively in patients subjected to AVR combined with application of the CSD and controls, respectively (p < 0.05; Tables 4 and 5). Go Similarly, LVESD decreased from 56 ± 5 mm and 54 ± 8 mm preoperatively to 39 ± 8 and 35 ± 6 mm at 12 months postoperatively in patients subjected to AVR combined with application of the CSD and controls, respectively (p < 00.5; Tables 4 and 5).There were no significant changes in the cardiac function as measured by left ventricular ejection fraction (LVEF) in any of the two groups of operated patients (Tables 4 and 5).


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  		Table 4 The LVEDD, LVESD, and LVEF Measurements During the Study Period in Patients Subjected to AVR+CSD (Data Are Given As Mean ± Standard Deviation)
 

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  		Table 5 The LVEDD, LVESD, and LVEF Measurements During Study Period in Control Patients Subjected to AVR (Data Are Given As Mean ± Standard Deviation)
 
The TVI measurements showed only minor changes in LV global systolic function measured as mitral annular Sm from 8.1 ± 1.0 cm/s preoperatively to 7.6 ± 1.7 cm/s and 7.2 ± 1.3 cm/s at 3 and 12 months follow-up, respectively. Left ventricular diastolic function measured as mitral annular Em was slightly reduced from 10.1 ± 1.6 cm/s preoperatively to 6.9 ± 1.3 and 7.8 ± 1.1 cm/s at 3 and 12 months follow-up, respectively.

The right ventricular global systolic function measured as tricuspid annular Sm by TVI was reduced from 13.1 ± 1.8 cm/s preoperatively to 8 ± 1.0 cm/s and 9.2 ± 2.2 cm/s at 3 and 12 months follow-up, respectively. Right ventricular diastolic function measured as tricuspid annular Em was reduced from 11.9 ± 3.6 cm/s preoperatively to 5.3 ± 1.5 cm/s and 7.0 ± 2.9 cm/s at 3 and 12 months follow-up, respectively.

Endothelin Analysis
Preoperatively, circulating plasma levels of ET-1 and big ET-1 were 4.5 ± 0.2 femtomole (fmol)/mL and 0.27 ± 0.07 fmol/mL in patients undergoing AVR with application of the CSD. There were no significant changes in the circulating plasma levels of ET-1 and big ET-1 throughout the study period.


   Comment
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
Acknowledgments
 References
 
Studies have shown that the long-term prognosis among conservatively treated patients with moderately severe (3/4) or severe (4/4) AR that is asymptomatic, have an EF greater than 0.55 and LV systolic dimensions corrected for body surface area (LVS/BSA) less than 25 mm/m2 is excellent [2]. The importance of careful monitoring and early surgery if LV systolic dysfunction or LV dilatation develops in these patients has recently been shown [8].

In this study we have demonstrated that there were no statistically significant differences in changes regarding cardiac LV dimensions or LV systolic function between patients undergoing application of the CSD in addition to AVR and control patients undergoing AVR only. This was clearly demonstrated with regard to echocardiographic comparison with a control group of patients, as well as when analyzed with TVI in the CSD group only. The findings in the present study regarding patients with AR differ from the findings in patients with mitral regurgitation subjected to CSD application in conjunction with mitral valve surgery presented by Acker and colleagues [5]. One possible mechanism could be that mitral regurgitation presents a pure volume overload to the ventricle in contrast to an AR that presents both a pressure and volume overload to the ventricle.

Previous echocardiographic investigations of the RV function measured as tricuspid annular motion in patients after CABG have shown a depressed RV function with no signs of reversal at 12 months postoperatively [9]. The TVI examination of patients with dilated cardiomyopathy undergoing application of the CSD concomitant with other open heart surgery have also shown detrimental effects on RV function. This is especially apparent in a reduction of the RV diastolic function with no signs of improvement during the first 12 months postoperatively [10]. The results of the TVI investigations performed in the present study thus confirm earlier findings regarding RV function. However, the clinical importance of the depressed diastolic RV function remains to be established. In contrast to our findings, electron-beam computed tomographic examination one month postoperatively of patients with idiopathic dilated cardiomyopathy undergoing application of the CSD have shown reduced RV size and improved RV performance [11].

Circulating plasma levels of ET-1 are increased in heart failure patients and correlate with the prognosis in these patients [12, 13]. It has also earlier been shown that there is a correlation between reversed remodeling in dilated cardiomyopathy by passive containment surgery and decreased circulating plasma levels of ET-1 [7]. The findings in this study regarding the ET-1 levels are congruent with earlier findings because the patients in this study showed no signs of heart failure. Furthermore, the unchanged levels of circulating plasma levels of ET-1 in our patients undergoing AVR and CSD application indicate that there is no correlation between LV diameter per se and the circulating plasma levels of ET-1 in nonfailing patients.

A major limitation of this study is the small number of patients in each group. This is due to the fact that the number of patients in our institution meeting the inclusion criteria is limited. Much larger groups of patients would be needed for a well-powered evaluation, but based on the present study there seems to be no major beneficial effects of addition of the CSD to AVR. Any major, significant effect on the studied parameters should have been detected in the present study population. The follow-up time is limited to 12 months, but after AVR a decrease in cardiac dimensions in patients with AR occurs in the early postoperative cause and few changes are seen after more than six to eight months postoperatively [3]. Based on these facts we believe that the observation period in this study is sufficient to detect any effects of the CSD application.

In conclusion, this case-control study has shown that application of the CSD concomitant with AVR in patients with longstanding moderately severe or severe AR and LV dilatation is safe, easy, and can be performed without any apparent negative effects. However, no additive effects are seen with regard to reversed remodeling or improved LV function.


   Acknowledgments
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
 Acknowledgments
References
 
This study was supported by the Familjen Janne Elgqvist Foundation, the Mats Kleberg Foundation, and funds from the Karolinska Institutet. None of the authors has any financial connection with Acorn Cardiovascular, Inc. and no financial support has been received for this study by Acorn Cardiovascular, Inc. The assistance from Elisabeth Berg of the Medical Statistics Unit, Department of Medical Informatics, and Educational Development, Karolinska Institutet, in the statistical evaluation of the data is acknowledged.


   References
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
 Acknowledgments
 References
 

  1. Bonow RO. Aortic regurgitation Curr Treat Options Cardiovasc Med 2000;2:125-132.[Medline]
  2. Dujardin KS, Enriqus-Sarano M, Schaff HV, Bailey KR, Seward JB, Tajik AJ. Mortality and morbidity of aortic regurgitation in clinical practice: a long term follow-up study Circulation 1999;99:1851-1857.[Abstract/Free Full Text]
  3. Bonow RO, Dodd JT, Maron BJ, et al. Long-term serial changes in left ventricular function and reversal of ventricular dilatation after valve replacement for chronic aortic regurgitation Circulation 1988;78:1108-1120.[Abstract/Free Full Text]
  4. Konertz WF, Shapland JE, Hotz H, et al. Passive containment and reverse remodelling by a novel textile cardiac support device Circulation 2001;104(suppl I):270-275.
  5. Acker MA, Bolling S, Shemin R, et al. Mitral valve surgery in heart failure: insights from the Acorn clinical trial J Thorac Cardiovasc Surg 2006;132:568-577.[Abstract/Free Full Text]
  6. Franco-Cereceda A, Lockowandt U, Liska J, Olsson A. Reversal of ventricular dilatation in aortic regurgitation after valve replacement and cardiac support implant surgery using the Cor Cap Cardiac Support Device Ann Thorac Surg 2005;80:315-316.[Abstract/Free Full Text]
  7. Bredin F, Franco-Cereceda A. Reversed remodeling in dilated cardiomyopathy by passive containment surgery is associated with decreased circulating levels of endothelin-1 Eur J Cardiothorac Surg 2006;29:299-303.[Abstract/Free Full Text]
  8. Tornos P, Sambola A, Permanyer-Miralda G, Evangelista A, Gomes Z, Soler-Soler J. Long-term outcome of surgically treated aortic regurgitation influence of guideline adherence toward early surgery J Am Coll Cardiol 2006;47:1012-1017.[Abstract/Free Full Text]
  9. Alam M, Hedman A, Nordlander R, Samad B. Right ventricular function before and after an uncomplicated coronary bypass graft as assessed by pulse wave tissue imaging of the tricuspid annulus Am Heart J 2003;146:520-526.[Medline]
  10. Olsson A, Bredin F, Franco-Cereceda A. Echocardiographic findings using tissue velocity imaging following passive containment surgery with the Acorn CorCapTM cardiac support device Eur J Cardiothorac Surg 2005;28:448-453.[Abstract/Free Full Text]
  11. Lembcke A, Dushe S, Sonntag S, et al. Changes in right ventricular dimensions and performance after passive cardiac containment Ann Thorac Surg 2004;78:900-905.[Abstract/Free Full Text]
  12. Wei CM, Lerman A, Rodeheffer RJ, et al. Endothelin in human congestive heart failure Circulation 1994;89:1580-1586.[Abstract/Free Full Text]
  13. Pousett F, Isnard R, Lechatt P, et al. Prognostic value of plasma endothelin-1 in patients with chronic heart failure Eur Heart J 1997;18:254-258.[Abstract/Free Full Text]

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