The Memory of the Heart

Abstract

The embryological development of the heart is one of the most fascinating phenomena in nature and so is its final structure and function. The various ontogenetic passages form the evolutive basis of the final configuration of the heart. Each key step can be recognized in the final features, as the heart maintains a kind of "memory" of these passages. We can identify the major lines of development of the heart and trace these lines up to the mature organ. The aim of this review is to identify these key parameters of cardiac structure and function as essential elements of the heart's proper functioning and bases for its treatment. We aim to track key steps of heart development to identify what it "remembers" and maintains in its final form as positively selected. A new vision based on the whole acquired knowledge must guide an in-depth scientific approach in future papers and guidelines on the topic and a complete, farsighted therapeutic conduct able to ensure the physiological correction of cardiac pathologies. The application of this modern, functional vision of the heart could improve the clinical treatment of heart disease, filling the gaps still present.

Keywords: cardiac resynchronization; cardiomyopathy; guidelines; heart embryology; heart failure; interlaced myocardial fibers; left ventricular reconstruction; mitral regurgitation; myocardial structure; valve disease.

Figure 1

“Instrumento mirabile invenzionato dal sommo maestro”, Leonardo da Vinci, Dell’Anatomia, 1489, Fogli B, readable mirror image of Figure 64, foglio 12, recto; public domain electronic copy at: https://archive.org/stream/imanoscrittidile00leon#page/2.

Figure 2

J. Bell. Pettigrew, The physiology of circulation, Publisher Macmillan, London, 1874, Figure 139, page 215, engraved on wood, (left, public domain electronic copy at https://archive.org/details/b20401619). Note the clear similarity with the Torrent–Guasp myocardial band, 1998 (right, adapted from http:// www.torrent-guasp.com/pages/vmb%20form.htm).

Figure 3

Echo color Doppler (A,B) and Pulsed Doppler (a,b) study of diastolic (A,a) and systolic (B,b) intra-ventricular flows in a healthy volunteer. The color homogeneity and the black areas under the pulsed curves indicate a laminar flow.

Figure 4

The “W” flows inside the heart (yellow lines).

Figure 5

Adult heart conduction system that depicts the original single starting point in the ex sinus venosus area (sino-atrial node), the atrioventricular node and the subsequent more capillary branches that follow the myofibrillar development of cardiac ventricles.

Figure 6

Coronary vessels and fiber orientation. (A) Epicardial course of coronary arteries crossing fiber orientation. The shaded area depicts transmural necrosis induced by coronary vessel occlusion which concerns a sector of myocardium made by several strata of differently oriented myocardial fibers. (B) At the border zone, still normal myocardium with still normal fiber orientation interlaces with the necrotic tissue. Necrotic tissue discontinues contiguity of myocardial fibers, although they remain normally oriented in the thickness of normal myocardium. Once fibrotic tissue is removed, the surgical suture matches the correspondent points (“a” with “a1”, “b” with “b1” etc.) restoring the contiguity of residual, normal bundles of fibers. Adapted from the reference [76]. Fiber picture was obtained by the DTI Track module of MedINRIA open source software (download at https://med.inria.fr/).

Figure 7

Surgical technique to re-approach fibers’ bundles in a physiologic disposition. Panels (A) and (B) depict the stretching of the suture that approaches and fits the lateral ventricular wall to the patch. The arrow in panel (B) shows how the suture redirects fiber orientation, approaching a farer point of the myocardial wall to a nearer point on the patch. Adapted from the reference [76].