Ventricular structures must be understood during surgical restoration for heart failure.

Scandinavian Journal of Surgery 96: 164–176, 2007 Ventricular structures must be understood during surgical restoration for heart failure G. D. Buckberg Division of Cardiothoracic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California, U.S.A. California Institute of Technology, Pasadena, California, U.S.A. Key words: Ventricular restoration; helical ventricular myocardial band; ischemic cardiomyopathy; non-ischemic cardiomyopathy; valvular cardiomyopathy; ��� ���� �� ventricular fiber orientation; SAVE; Pacopexy Introduction The central theme of cardiac surgery is that alteration of structure improves function, and this concept is fundamental during surgical restoration of dilated hearts in cardiac failure. Adherence to this goal re- quires a clear knowledge of the normal conical ven- tricular form, recognition of how disease caused ar- chitectural deterioration towards a spherical shape that impairs performance, and why rebuilding struc- ture returns function towards normal. The keynote knowledge governing surgical decisions relates to understanding how operative modifications affect left ventricle spatial relationships. The conical pattern of normal cardiac size and shape is well known and the underlying spatial ar- rangements are closely linked to the helical ventricu- lar myocardial band (1) comprised of a surrounding wrap of the basal loop with transverse fibers and an apical loop of reciprocal oblique fibers forming a spi- ral vortex at the apex as shown in Fig. 1A. The spher- ical configuration of the enlarged global ventricle widens the apical loop (Fig. 1B) by making the oblique apical loop fibers develop a transverse orien- tation that more closely resembles the horizontal fiber orientation of the basal loop. The bioengineering infrastructure for this mechan- ical change in size and shape reduces ejection frac- tion, which is 60% with oblique fiber direction and lowered to 30% when fiber orientation is transverse (2). This architectural disadvantage limits deforma- tion (or twisting capacity that is visible at operation or by MRI recordings) to negatively impact the natu- ral increment from mid wall to apex (3) and thus impair sequential contraction efficiency which limits performance by producing mechanical dyssynchrony. Furthermore, secondary mitral incompetence follows chamber widening and supplemental modifications during ventricular restoration that offset these c hanges will be described. Symptoms of arrhythmia and cardiac failure, co- equal causes of mortality, worsen as ventricular size progressively increases. Surgical correction of the di- lated heart requires changing the spherical configura- tion architecture into a more normal elliptical form (4), and simultaneously rebuilds more normal inter- nal spatial components. The primary and secondary geometric events will be summarized and serve as the basis of developing procedures used to alter ven- tricular size, shape, the apical tip, papillary muscle inter space basal width, and inferior wall toward nor- mal. The disease and the ventricle and secondary mitral changes Enlarged ventricular size with the spherical shape becomes a unifying theme of dilated cardiomyopathy. (Fig. 2) The underlying pathologic processes respon- sible for spherical configuration range from a) i schemic disease causing an extensive postmyocar- dial infarction scar leading to secondary stretch of compensatory remote fibers within unscarred muscle, or global stretch from multiple small scars, but with- out a large asynergic region, b) non-ischemic disease causing distention stretch from volume loading fol- lowing mitral or aortic valve incompetence, or c) non- ischemic cardiomyopathy destroying segments of re gional myocardial fibers with secondary distention of remaining hypertrophied and thicker viable muscle. The secondary changes that cause associated mi- tral incompetence include ventricular stretch that alters leaflet coaptation, widening of the mitral an- Correspondence: Gerald Buckberg, M.D. David Geffen School of Medicine at UCLA Division of Cardiothoracic Surgery 62-258 Center for the Health Sciences Los Angeles, CA 90095-1701 U.S.A. Email: gbuckberg@mednet.ucla.edu