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It only takes a cursory look at a beating heart to realise that the heart contracts with a twisting motion. This has been commented on over several centuries.1 This twisting motion pulls the mitral and tricuspid valve down towards the apex in systole and involves the coordinated action of longitudinal, circumferential and radial orientated fibres.2 3 Immediately after aortic valve closure as the myocytes begin to relax untwisting starts using the energy stored during systole within ventricular and atrial myocytes and the interstitium. This energy creates the negative pressure gradient that produces ventricular suction that is a vital process in the normal heart as it allows rapid filling at low pressures.4 5 After the left ventricular (LV) pressure has fallen the atrioventricular (AV) plane springs back to its equilibrium position moving around the column of blood passing through the mitral valve thus aiding filling of the ventricle. By this simple mechanism blood that was in the left atrium finds itself in the ventricle.6 Thus the longitudinal movement of the mitral and tricuspid annulus—akin to a pumping action—is a major component of normal function in both left and right ventricles. The importance of this was confirmed in a recent study using magnetic resonance imaging which quantified the percentage of the stroke volume due to longitudinal AV plane displacement (AVPD) in normal subjects, elite athletes and patients with dilated cardiomyopathy and an ejection fraction <30%.7 It was found that although stroke volume was higher in the athletes and lower in the patients with cardiomyopathy (as would be expected), the percentage of the stroke volume explained …
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