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Eur J Cardiothorac Surg 2006;29:S213-S215
© 2006 Elsevier Science NL
Editorial |
a Option on Bioengineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
b David Geffen School of Medicine at UCLA, Box 951741, 62-258 CHS, Los Angeles, CA 90095-1741, USA
* Corresponding author. Address: Division of Cardiothoracic Surgery, 62-258 Center for the Health Sciences, Los Angeles, CA 90095-1701, USA. Tel.: +1 310 206 1027; fax: +1 310 825 5895. (Email: gbuckberg{at}mednet.ucla.edu).
A collaborative approach to congestive heart failure management has evolved within the International RESTORE Team comprised of cardiologists and surgeons, representing the four continents of North America (United States), Europe, South America and Asia. This group celebrated its 10th conference at the AATS meeting in San Francisco, and Table 1 lists the sites of prior gatherings. The goals of this integrated team include discussion and application of new concepts about understanding and managing the spectrum of diseases that cause dilated cardiomyopathy from ischemic, valvular and nonischemic causes. Interaction during meetings always includes input from non-RESTORE experts with novel views on CHF topics.
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The diagnostic and follow-up role of MRI was presented to determine if this imaging modality could provide one stop shopping to obtain several established clinical guidelines. These include recognition of the amount of asynergy, remote muscle evaluation, end systolic volume index, ejection fraction, wall thickness, viability of ischemic and remote muscle by gadolinium, mitral annular dimension, papillary muscle width, tagging to define deformation. Discrete result examples and time frames were generated to achieve this goal.
A yardstick of geometric change during cardiac failure is the conversion of the normal elliptical ventricular shape to a spherical contour. This sphericity concept is based on a dimensional change that accounts for length and width of the overall chamber. Global heart sphericity changes normally occur in nonischemic disease, following chronic valve insufficiency, and late after extensive infarction with stretch of remote muscle. However, the infarction scar initially causes a nonuniform change in the damaged region, does not immediately affect global sphericity, but routinely deforms the apex to change regional ventricular conicity. The new Apical Conicity Index is introduced by Di Donato to account for the nonuniform geometric change.
Key notes to prognosis following restoration involve two vital categories of adequate myocardial protection and a technically competent geometric procedure. The registry of the RESTORE report of
1200 patients was reviewed, to compare restoration results when either cardioplegia or the beating heart were employed during rebuilding. Furthermore, an overall review of experimental studies performed in dilated failing hearts was presented to define differences in these methods capacity to nourish LV subendocardial muscle, the most vulnerable area to intraoperative ischemia. Issues related to recognition of the concept of vascular remodeling were addressed, as well as providing guidelines for the importance of maintaining a mean perfusion higher pressure during restoration.
Geometric principles of restoration have been linked to the spatial geometry of the left ventricle, as described by Torrent-Guasp who unfortunately passed away in early 2005. However, the structural basis for normal geometry was presented to the American Association of Clinical Anatomists in 2004. Arthur Dalley, the AACA President, stated during his introduction that Modern technology changes many things but not anatomy, now the ventricular myocardial band has changed anatomy. That comment sets the framework for future learning, and helical configuration concepts must be tested since they may become the end points as novel restoration procedures evolve.
Fig. 1 shows the postulation of how heart failure alters normal geometric configuration. Fig. 2 displays the interaction between descending segment geometry from the normal heart model, MRI evidence of acceleration tracts from velocity curves from Jung et al. [13] at Freiburg, Germany and by corrosion casts by Gorodkov et al. [14] at the Bakoulev Scientific Institute in Moscow that define how the spiral ventricular muscle trabeculae compress blood in the cavity.
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Spatial knowledge of the overall geometry of the ventricular chamber was also blended with recognition that natural papillary muscle position maintains the conical shape in the normal heart, but this position changes during dilation to impair mitral valve function by altering tethering, and simultaneously contribute to the sphere formation by widening the interpapillary muscle distance. Buffolo summarized his experience in using mitral valve replacement rather than repair to treat secondary mitral insufficiency in ischemic and nonischemic dilated cardiomyopathy. The approach of bringing the stretched and tethered papillary muscle into a new position adjacent to the annulus during mitral valve replacement restored shape, improved conicity, shrinks volume and allowed favorable late survival in far advanced NYHA patients with congestive heart failure.
The final two reports relate to how geometry effects right ventricular function. The underlying analysis is linked to septal function, and new studies demonstrate why septal anatomy derives from the same geometric structures as the left ventricular free wall within the helical ventricular myocardial band. Sonomicrometer analyses imply that the septum should be considered the right ventricular lion, since the oblique fibers that form septal architecture are responsible for its vital twisting action.
Clinical follow-up includes early pilot studies by Frigiola et al. [15] that demonstrate the advantages of restoring function by right ventricular rebuilding in patients presenting with right ventricular failure after chronic pulmonary regurgitation after tetralogy of Fallot repair. Substantial improvement of right ventricular function, and alleviation of ventricular arrhythmias followed reconstruction of septal architecture and exclusion of part of the dilated nonfunctional free wall during pulmonary valve replacement.
This overview surveys the topics discussed during the recent RESTORE meeting. The contributors to this issue appreciate the European Journal of Cardiothoracic Surgery providing the opportunity to summarize these reports in a single publication that includes preliminary and completed studies of diagnosis and treatment of congestive heart failure. The meeting goal always includes seminal studies by the RESTORE team, together with sharing new looks at the CHF by participating non-RESTORE investigators. The initial RESTORE reports about ischemic cardiomyopathy after anterior infarction [2,16] reflects the initiation of the Group's broad scope of CHF interests. The broad series of manuscripts that follows this overview defines the breadth of interest and curiosity of the RESTORE membership.
References
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