DOI: 10.1148/radiol.2462070625
(Radiology 2008;246:652-653.)
© RSNA, 2008
Surgical Ventricular Restoration and Left Ventricular Function
Ze-Zhou Song, MM
Department of Ultrasound, The First Affiliated Hospital, College of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou, Zhejiang Province, People's Republic of China e-mail: zezhou_song{at}126.com
Editor:
I read with great interest the article by Dr Carmichael and colleagues (1), in the December 2006 issue of Radiology, which confirmed that although volume-based indexes of global left ventricular (LV) function improve significantly after surgical ventricular restoration (SVR), regional LV function did not improve significantly; there was evidence of continued LV remodeling after SVR. The methods and interpretation of the results, however, raise several concerns.
In this article, Dr Carmichael and colleagues (1) report that at pre-SVR examination, there were no statistically significant differences in any of the global LV functional parameters between those patients who underwent early post-SVR examination (n = 95) and those who did not undergo early post-SVR examination (n = 10). Similarly, there were no statistically significant differences in any global LV functional parameters between those patients who underwent late post-SVR examination (n = 35) and those who did not undergo late post-SVR examination (n = 70). However, SVR either was performed alone (n = 6) or was combined with coronary artery bypass graft surgery (n = 46), combined with mitral valve repair (n = 11), or combined with both coronary artery bypass graft surgery and mitral valve repair (n = 42), which could affect global and regional LV function differently. The differences in surgical modality between those patients who underwent early post-SVR examination and those who did not undergo early post-SVR examination or between those patients who underwent late post-SVR examination and those who did not undergo late post-SVR examination were not well described. And then, were there any relations of surgical modality to the changes in global and regional LV function and LV structure? That is to say, could the surgical modality affect the results of this study in which there was evidence of continued LV remodeling after SVR?
In this study by Dr Carmichael and colleagues (1), the authors thought that there was evidence of continued LV remodeling after SVR because regional LV function did not improve significantly. However, it is well known that LV remodeling includes LV structure remodeling and function remodeling, and LV structure remodeling and function remodeling could be very important in the genesis and advancement of heart failure. LV mass and index and LV wall thickness are very good parameters to evaluate left ventricular structure remodeling, which could be calculated by means of echocardiography and magnetic resonance (MR) imaging. In this study by Dr Carmichael and colleagues (1), however, LV mass and index and LV wall thickness were not well described. That is to say, it is not confirmed that there was evidence of continued LV structure remodeling after SVR, and this needs to be further studied.
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REFERENCE
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- Carmichael BB, Setser RM, Stillman AE, et al. Effects of surgical ventricular restoration on left ventricular function: dynamic MR imaging. Radiology 2006;241:710–717.[Abstract/Free Full Text]
Response
Randolph M. Setser, DSc *,
Brett B. Carmichael, MD 
, and
Richard D. White, MD 
* Division of Radiology, the Cleveland Clinic Foundation, HB6, 9500 Euclid Avenue, Cleveland, OH 44195 * e-mail: setserr{at}ccf.org
Radiology Inc, Mishawaska, Ind
Department of Radiology, University of Florida College of Medicine, Jacksonville, Fla
We appreciate the interest generated by our study (1) and welcome the opportunity to address the comments of Dr Song in his Letter to the Editor. It is our understanding that Dr Song has three comments and/or questions regarding our study.
First, Dr Song cites our result that, before surgery, no statistically significant difference in LV function was found between those subjects who did undergo postsurgical MR imaging and those who did not. It seems that he then attempts to link these presurgical results with the effects of surgery—that is, SVR with or without coronary artery bypass graft surgery and/or mitral valve repair. However, the pre-SVR results were reported only to show that there was consistency in LV function between patient subgroups prior to surgery; these results have no bearing on the various surgical procedures that accompanied SVR. Thus, we do not believe there is any substantive link between the presurgical comparison of patients who did or did not undergo postsurgical MR imaging and the effects of surgery.
Second, Dr Song believes that we did not adequately describe the individual effects of the surgical procedures that accompanied SVR and questions whether their clinical and/or mechanistic effects could have been elucidated by using our data. Although we acknowledge that additional, concurrent surgical procedures certainly affect LV function following SVR, the reality is that very few patients undergo SVR in isolation (only 6% in our study), while the majority also undergo coronary artery bypass graft surgery (84%) and/or mitral valve repair (50%); these values are consistent with overall numbers from our institution (2). Furthermore, although 105 patients underwent a pre-SVR MR examination (the number quoted in the letter), only 35 underwent a late (ie, >6 months after SVR) postsurgical MR examination, with an insufficient number of patients in each subgroup to support the analysis Dr Song is proposing. Perhaps an animal model would be most appropriate to answer this question (3).
Last, Dr Song believes that we did not provide adequate justification for continued LV remodeling after surgery, suggesting that LV mass (or mass index) and wall thickness results should have been reported, as well. We agree that LV mass (or index) would have been the ideal parameter to use for characterizing LV remodeling between the early and late postsurgical examinations. However, the purpose of this study, as stated in the introduction, was to "evaluate the changes in global and regional LV function after SVR." Because LV volumes were computed for this purpose, we reported these values at each time point, but did not compute LV mass since it was not needed to support our stated goal. Furthermore, the use of LV volumes as evidence of continued LV remodeling following surgery was consistent with previous reports (4,5).
We trust that our responses will satisfy the readers of our published article.
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References
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- Carmichael BB, Setser RM, Stillman AE, et al. Effects of surgical ventricular restoration on left ventricular function: dynamic MR imaging. Radiology 2006;241:710–717.[Abstract/Free Full Text]
- O'Neill JO, Starling RC, McCarthy PM, et al. The impact of left ventricular reconstruction on survival in patients with ischemic cardiomyopathy. Eur J Cardiothorac Surg 2006;30:753–759.[Abstract/Free Full Text]
- Nishina T, Nishimura K, Yuasa S, et al. A rat model of ischemic cardiomyopathy for investigating left ventricular volume reduction surgery. J Card Surg 2002;17:155–162.[CrossRef][Medline]
- Dor V, Sabatier M, Di Donato M, Montiglio F, Toso A, Maioli M. Efficacy of endoventricular patch plasty in large postinfarction akinetic scar and severe left ventricular dysfunction: comparison with a series of large dyskinetic scars. J Thorac Cardiovasc Surg 1998;116:50–59.[Abstract/Free Full Text]
- Kokaji K, Okamoto M, Hotoda K, Maehara T, Kumamaru H, Koizumi K. Efficacy of endoventricular circular patch plasty (Dor operation). Jpn J Thorac Cardiovasc Surg 2004;52:1–10.[CrossRef][Medline]
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