IJCS | Volume 31, Nº6, November / December 2018

664 Charles André Remoras and spontaneous echocardiographic contrast Int J Cardiovasc Sci. 2018;31(6)662-666 Viewpoint dorsal fins take the form of an oval slat-like structure with flexible membranes with thousands of spicules that increase friction forces (Figure 2a). This structure can generate suction and attach firmly on the smooth skin of large fishes – sharks, rays, tuna, swordfishes - and other animals such as dolphins, whales, dugongs andmanatees, turtles etc. (Figure 2b). They can also attach themselves to boats and ships. Sliding backwards increases the negative pressure and suction andmoving forward allows detachment from the surface and free swimming. Remoras and their hosts live in commensality. Remoras eat the host’s feces, leftovers, parasites and clean epidermal sloughing, whereas hosts confer protection, transport, promote fast passage of fluid through the gills and hence passive ventilation and energy sparing. The termRemora is derived from the Latin (Hindrance; to defer, delay, linger) and is a composite of re (back, again) and mora (delay). The family name – Echeneidae (1810) – also refers to the mythic property of this fish ( Echein – to hold, possess; and Naus - ship). Evidence of any deleterious hydrodynamic effects of the attachment of remoras to fishes or ships is, however, scarce or absent. Additional effort fromhydrodynamic strain andmetabolic demand for food imposed by the attachment of remoras to large fishes or dolphins are minimal ( circa 1%), even at high speed (e.g., 500 cm/s). This, however, depends on the number of remoras attached and the size of the host. 5 Remora as blood stasis Cardiac blood stasis and its thrombogenic potential have been described for a long time. René Théophile Hyacynthe Laennec (1781-1826), who made extensive autopsy studies of his patients, does not refer to it in the first edition of his treatise on auscultation and lung and heart diseases (1819). However, he clearly mentions ” la stase du sang ” in Chapter XIX ( De l’ inflammation de la Membrane Interne du Coeur et des Gros Vaisseux , pp. 598- 618) of the expanded and even more influential second edition of the Traité (1826). The term remora was already in use in the 19th century to describe biological fluid stasis. As for intracardiac blood, the above text (the Traité , 1826) was translated into English by John Forbes (p. 663), as follows: “From all previous reports I believe we can draw the following conclusions – 1. Remora of the blood, in consequence of obstruction to its flow, is sufficient to produce coagulation, and to determine the formation of a coagulum of organizable fibrin. All causes capable of occasioning remora, particularly mechanical obstruction to circulation and repeated and prolonged episodes of syncope, seem to me sufficient to produce this effect”. 6 Spontaneous echocardiographic contrast In 1975, Feigenbaum, usingM-mode echocardiography, described left intracavitary echoes near dyskinetic segments of the left ventricle and thrombi in patients with coronary artery disease. Human and animal studies using real-time two-dimensional echocardiography confirmed that these variables – density and conformation echoes – moved in slow circles and were due to the sluggish blood flow caused by severe wall motion abnormalities, 7 which could be found even during anticoagulation treatment and were also detected within abdominal aortic aneurysms. These echoes “resembled smoke moving slowly through a light beaminadark room”. 7 Increasing layeringandalignment of redbloodcells ( rouleau ) in low-flowandwhirling conditions are responsible for the increased echogenicity. 7 Iliceto et al. first described dynamic intracavitary echoes – defined as a cloud of low-intensity echoes slowly moving in a circular or spiral shape – in the enlarged left atrium of 10 patients with severe mitral stenosis and AF. 8 At that time, correlation of SECwith thrombogenesis was already well established. Most thrombi in patients with AF (90%) or mitral stenosis (60%) are detected in the LAA. 1 SEC is also most commonly seen in this structure. In the setting of stroke of unknown etiology, the presence of SEC in the LAA indicates a probable cardioembolic origin, even in the absence of thrombus. 9 LAA is an important contractile and multilobulated structure, whose dysfunction is the main cause of clot formation in AF, mitral stenosis, myocardial stunning after cardioversion, etc. SEC and thrombi are more frequently detected in patients with LAA contractile dysfunction. A comprehensive study of the LAA is currently performed using transesophageal echocardiography includingmultiple imaging planes, pulsedwave-Doppler and tissue strain techniques. 1,10 These techniques provide an accurate analysis of LAA’s contractile properties and demonstrate good correlation with the presence of SEC or thrombus and with thromboembolic risk. 1,11 Conclusion Thrombogenesis in FA and other conditions with slow atrial flow involves the complex interplay of