Eur J Cardiothorac Surg 2006;29S:S207-S212

 

 

 

A new concept of ventricular restoration for nonischemic dilated cardiomyopath

 

Hisayoshi Suma, Taiko Horii, Tadashi Isomura, Gerald Buckberg and the RESTORE Group

Abstract
Objective: Left ventricular restoration is used to treat patients with chronic progressive heart failure caused by nonischemic dilated cardiomyopathy. This study addresses the use of site selection to determine either lateral wall or septal exclusion. Methods: Evolution of intraoperative echocardiography to define the site of poorest contraction and use of multiple biopsies to show the nonhomogeneous nature of damage are reviewed. To address the heterogeneity of extent of fibrosis in nonischemic cardiomyopathy, target selection was used to determine the mode of left ventriculoplasty. Either the lateral wall was excluded by partial left ventriculectomy (PLV) or septal anterior ventricular exclusion (SAVE or Pacopexy) was employed if the septum was primarily diseased. Surgical results in 107 high-risk (43% NYHA (New York Heart Association) class III and 57% class IV) patients with idiopathic dilated cardiomyopathy over the past 9 years are reviewed.
Results: Overall hospital mortality was 7.1% in 84 elective operations and 60.9%in 23 emergencyoperations, and fell from42.8% (6 of 14) to 15.0% (14 of 93), when site selection for the area of left ventricular excision or exclusion was determined by the intraoperative echocardiography test. The SAVE/Pacopexy procedure was performed in 36 patients with 62.2% 5-year survival rate. For the entire cohort of PLV and SAVE/Pacopexy population, overall ejection fraction increased from 20 to 31%, and NYHA class improved from 3.6 to 1.8. The 1 -, 5-, and 7-year survival rates were 66.9, 46.0, and 36.2%, respectively. In patients having the operation before inotropic dependent, the survival rate was 78.1, 58.0, and 50.2%, respectively.
Conclusions: Left ventriculoplasty is effective for patients with idiopathic dilated cardiomyopathy with heart failure by proper patient selection, appropriate timing of the operation, and choice of the surgical procedure (exclusion site selection).

Keywords: Idiopathic dilated cardiomyopathy; Heart failure ventriculoplasty; Site selection; SAVE; Pacopexy

 
Introduction
Surgical treatment of nonischemic dilated cardiomyopathy is a new field in cardiac surgery [1]. Although current pharmacologic therapy has produced improved survival, many patients still need heart transplantation although it is not available enough due to shortage of donors. Ventricular restoration by left ventriculoplasty has evolved as proposed by Dor et al. [2] to treat ischemic cardiomyopathy and by Batista et al. [3] to treat mostly nonischemic cardiomyopathy. The Dor procedure directly excludes scarred muscle, and had been successful, but the Batista operation has been unsuccessful because of high operative mortality and recurrence of heart failure. One of the reasons for failure is that the operation has approached a global chamber thought to contain homogeneous disease in idiopathic cardiomyopathy.

Accumulated data shows variable results [4] so that the homogeneous disease concept may be an incorrect presumption. In idiopathic dilated cardiomyopathy, we found that a concept of homogeneous global disease was incorrect, as biopsy specimens of the septal and lateral ventricular wall in our initial surgical series showed nonhomogeneous disease with variability in scarring ranging from 4 to 60% between free wall and septum [5]. This nonuniform pathology indicates that prior adverse results are not surprising following excision of minimally diseased lateral wall while retaining a very fibrotic septum for postoperative function even if the left ventricle was properly downsized.
These observations led to our introduction of intraoperative echographic evaluation to assess the regional contractile response [1,5,6] to aid clinical site selection and improve surgical results. The basic concept of an intraoperative echocardiography-guided volume reduction test is that initiation of partial cardiopulmonary bypass will decompress the dilated stretched chamber，and induce visualizable functional changes of Left ventricular wall motion and thickness．These observed wall motion changes（Fig．1）［2］led to site selection of the most diseased region to be excluded This concept to exclude the LV culprit lesion，While retaining more viable muscle to resume function following restoration，was very common in surgery for ischemic heart disease，since the scar is evident from the akinetic of dyskineic segment．Conversely，consideration of a nonhomogeneous region is a very new consideration in nonischemic cardiomyopathy（Fig．2）．
When the intraoperative echocardiography test showed that the septum is the weakest part，we apply the septal anterior ventricular exclusion（SAVE）which was introduced and named by Suma［5，7，8］，or Pacopexy named by Buckberg [9］．The term，Pocopexy was selected to recognize the contributions of Francisco （Paco）Torrent−Guasp，Whose ingenious anatomic concepts defined the helical ventricular myocardial band and furthered our understanding of basic Structure/function relationshjps[10，11］．The intent is to make an ellipsoid ventricle，and a long and narrow endoventricular Patch is placed along the septum with interrupted mattress sutures so that the septum and a part of the anterior wall are excluded Surgical technique is shown in Fig．3．

Results
In the last 9 years，107 patients with idiopathic dilated cardiomyopathy underwent ventriculoplasty with mitral valve reconstruction（Fig．4）．There were 91 men and 16 women and their age ranged from 14 to 76 years with a mean of 53 years．All patients had medically refractory heart failure with New York Heart Association（NYHA） class III in 46 patients（43%）and class IV in 61 patients（57%），and 40 patients（37%）were supported by inotropic infusion before the surgery（Table 1）．
Mean duration of heart failure history was 5.5 years，and all patients were treated with β−blocking agents and ACE inhibitors．Preoperative variables are shown in Table 4．
Among 107 patients，84 patients underwent elective procedures，and the other 23　patients had emergency operations because of rapid deterioration of cardiopulmonary function with ongoing shock with multiorgan failure or cardiac arrest．The performed procedures were shown in Table 2．The resultant in-hospital mortality was 7.1%（6 of 84） for elective surgeries，and rose to 60.9%（14 of 13）in emergency surgeries．The overall hospital mortality was 17.4%（20 of 107）for the total experience．
Mechanical support with intra-aortic balloon pump and/or left ventricular assist device（LVAD）was needed，respectively，in 18 and 3 patients during the perioperative period．The major cause of death was heart failure and multiorgan failure．Overall hospital mortality decreased from 42.8%（6 of 14） to 15.0％（14 of 93），When site selection for the area of left ventricular excision or exclusion was determined by the intraoperative echocardiography test（Table 3）．Elective procedure mortality was decreased from 22.2%（2 of 9）to 5.3%（4 of 75）by excluding the weakest area．The regional evaluation led to the SAVE procedure that was performed in 36 patients when the septal region was thought to be the weakest part．There were five hospital deaths and six late deaths，and the5−year survival rate was 62.2% in this particular procedure．
Postoperative hemodynamic data is shown in Table 4．Overall 1−，5−，and 7−year survival rates were 66.9，46.0 and 36.2%，respectively，but mortality results varied in regard to preoperative patient condition as shown in Fig．6； inotropic supported patients had lower post operative survival．
In the survivors，cardiac index and ejection function were increased left ventricular end diastolic pressure and brain natriuretic peptide（BNP） were steadily decreased in 3 years after the operation（Figs．5　and　6）．Synchronicity of intraventricular conduction also improved after the operation（Fig．7）．Functional classification improved，as NYHA status changed from the preoperative status of 3.6 to 1.8 during this follow-up interval．

Discussion
Heart transplantation is an established effective treatment for patients with end-Stage heart failure．There is，however，a marked mismatch in number of donors and waiting patients all over the world．An ongoing surgical effort exists to seek an effective nontransplant cardiac surgical procedure to restore ventricular function．Endoventricular patch plasty[1]，Partial left ventriculectomy（PLV）［2，12，13］，and mitral valve reconstruction[14] have been attempted and evaluated．In ischemic cardiomyopathy，postinfarction scar tissue has been treated by endoventricular patch plasty，as proposed by Dor et al．［2］，with low surgical mortality and favorable late outcome［15］．
The surgical challenge to manage nonischemic cardiomyopathy，however，is still unclear．Myocardial viability and its regional distribution is a difficult aspect to assess when making decisions for surgical intervention．In patients with globally dilated left ventricle with heart failure，end-stage means medically refractory severe heart failure with low ejection fraction，elevated pulmonary artery pressure，and associated with valvular insufficiency．However，precise information is lacking regarding extent of myocardial damage，and its reversibility．Batista et al．［3］haveintroduced PLV by using a very simple concept based on physics of Laplace’s law but has failed to show successful results because of（1）high surgical mortality，（2）concerns of diastolic dysfunction，（3）return of heart failure，and（4） postoperative malignant ventricular arrhythmia．
One of the most difficult problems is the return of heart failure，Which is probably caused by（1）recurrence of mitral regurgitation，（2）a remaining dilated lesion of the left ventricle，（3）too small the left ventricle caused by excessive excision，and（4）removal of the kinetic left ventricular wall with retention of poorly contractile regions．
Mitral annuloplasty with an undersized ring was proposed by Bolling et al．［14］，and has become relatively easily accepted because of low surgical mortality．But the extremely dilated left ventricle is not a favorable candidate for mitral annuloplasty alone in terms of late outcome．For successful ventricular restoration，properly site selected LV exclusion is important as shown here．In the beginning，we thought that the extent of myocardial disease was homogeneous in nonischemic cardiomyopathy．Therefore，the excision area was always the lateral wall as Batista proposed， and the anterior wall and ventricular septum were retained at the onset of our experience．At the end of the initial 14 experiences，preoperative echocardiographic evaluation showed that a certain number of patients had a less kinetic septum and relatively kinetic lateral wall．
Yanagida et al．［16］demonstrated the inhomogeneous extent of fibrosis and abnormal left ventricular wall motion with poorer contraction of the septum than the lateral wall I n significant number of patients with idiopathic cardiomyopathy．Also，pathologic analysis of surgical specimens taken from both the lateral wall and septum in our surgical series revealed inhomogeneity of interstitial fibrosis in those left ventricle．The overall mean% fibrosis was 19.1% in the lateral wall and 20.0% in the septum in 36 patients who underwent PLV． However，the range of fibrosis was extensive from 4 to 60%，with marked evidence of regional inhomogeneity（Fig．8）．In 33% of the patients，the septum had more fibrosis than the lateral wall，at measurement of 5% or more difference of %fibrosis between two sites．This disparity occurred in 17% of patients，When the fibrosis difference was 10%　or more．These findings strongly suggest that a poor surgical result will occur in patients with marked septal fibrosis if we perform the lateral PLV，? particularly with extensive excision beyond papillary muscles（Fig．9）．
Based on those findings and a new surgical strategy，SAVE/Pacopexy resulted in acceptable 5−year survival rate of 62.2% for endstage idiopathic dilated cardiomyopathy with bad septum．The underlying Strategy is to rebuild an ellipsoid ventricular chamber with an apex that resembles the architectural spatial relationships of the normal heart．This concept came from our knowledge of the helical ventricular myocardial band configuration described by Torrent−Guasp et al［10］．
We conclude that the ventriculoplasty can be effective When myocardial fibrosis is not severely diffused and the weakest region is detectable．Left ventriculoplasty is acceptably safe for elective operation，and clinical improvement can be obtained by proper surgical procedures and careful postoperative medical treatment．

References

  1. Suma H，lsomura T，Horii T，Sato T，Kikuchj N，lwahashi K，Hosokawa J．Nontransplant cardiac surgery for end−stage cardiomyopathy．J Thorac Cardiovasc Surg 2000；119：1233−45．
  2. Dor V，Sabatier M，Di Donato M，Montiglio F，Toso A，Maioli M．Efficacy of endoventricular patch plasty repair in large post−infarction akinetic scar and severe LV dysfunction．Comparison with a series of large dyskinetic scar．J Thorac Cardiovasc Surg 1998；116（1）：50−9．
  3. Batista RJV，Verde J，Nery P，Bocchjno L，Takeshita N，Bhayana JN， Bergsland J，Graham S，Houck JP；Salerno TA．Partial left ventriculectomy to treat end−stage heart disease．Ann Thorac Surg 1997；64：634−8．
  4. Ascione R，Lim KH，Chamberlain M，Al Ruzzeh S，Angelini GD．Early and late results of partial left ventriculectomy：Single center experience and review of the literature．J Card Surg 2003；18（3）：190−6．
  5. Suma H．Left ventriculoplasty for nonischemic dilated cardiomyopathy．Semin Thorac Cardjovasc Surg 2001；13（4）：514−21．
  6. Isomura T，Suma H，Horii T，Sato T， Kobashi T，Kanemitsu H，Hoshino J，Hisatomi K．Left ventricle restoration in patients with non−ischemic dilated cardiomyopathy：risk factors and predictors of outcome and Change of mid−term ventricular function．Eur J Cardiothorac Surg 2001；19（5）：684−9．
  7. Suma H，Isomura T，Horii T，Hisatomi K，Sato T， Kobashi T，Kanemitsu H，Hoshino J，Ueno H，Oda T， Left ventriculoplasty for non−ischemic cardiomyopathy with severe heart failure in 70 patients．J Cardiol 2001；37（1）：1−10．
  8. Suma H．Internal left ventrlcular reconstruction．Operative Tech Card Thorac Surg 2002；7：103−6．
  9. Buckberg GD，Coghlan HC，Torrent−Guasp F．The structure and function of the helical heart and its buttress wrapping．Vl．Geometric concepts of heart failure and use for structural correction．Semin Thorac Cardiovasc Surg 2001；13（4）：386−401．
  10. Torrent−Guasp F，Ballester M，Buckberg GD，Carreras F，Flotats A，Carrio I，Ferreira A，Samuels LE，Narula J．Spatial orientation of the ventricular muscle band：physiologic contribution and surgical implications．J Thorac Cardiovasc Surg 2001；122（2）：389−92．
  11. Buckberg GD，Coghlan HC，Torrent−Guasp F．The structure and function of the helical heart and its buttress wrapping．V．Anatomic and physiologic considerations in the healthy and failing heart．Semin Thorac Cardiovasc Surg 2001；13（4）：358−85．
  12. McCarthy PM，Starling RC，Wong J，Scalia G，MBuda T，Vargo RL，Goormastic M，Thomas JD，Smedira NG，Young JB．Early results with partial left ventriculectomy．J Thorac Cardiovasc Surg1997；114：1−11．
  13. Franco−Cereceda A，McCarthy PM，Blackstone EH，HOercher KJ，White JA，Young JB，Starling RC．Partial left ventriculectomy for dilated cardiomyoPathy：is this an alternative to transplantation．J Thorac Cardiovasc Surg 2001；121：879−93．
  14. Bolling SF，Pagani FD，Deeb GM，Bach DS．Intermediate−term outcome of mitral reconstruction in cardiomyopathy．J Thorac Cardiovasc Surg 1998；115（2）：381−6．
  15. Dor V．Left ventricular reconstruction：the aim and the reality after twenty years．J Thorac Cardiovasc Surg 2004；128（1）：17−20．
  16. Yanagjda R，Sugawara M，Kawai A，Koyanagi H．Regional differences in myocardial work of the left ventricle in patients with idiopathic dilated cardiomyopathy：implications for the surgical technique used for left ventriculoplasty．J Thorac Cardiovasc Surg　2001；122（3）：600−7．
European Journal of Cardio-thoracic Surgery 2006 　より