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Movements of the heart during ejection

1961; Elsevier BV; Volume: 62; Issue: 6 Linguagem: Inglês

10.1016/0002-8703(61)90668-8

1097-6744

Tinsley R. Harrison, Cecil Coghlan, Gustavo Prieto,

Anesthesia and Sedative Agents

The precordial movements (kinetocardiograms) of normal adults during ventricular ejection have been analyzed in relation to the velocity of pressure change in the cardiac chambers and great vessels of dogs. The data point toward the following general sequence of cardiac motion. A. During the period between the onset of left ventricular ejection and the start of the carotide upstroke: Three almost simultaneous precordial movements occur at this time. (1) Left ventricular recoil occurs and produces the normal brief apex tap as the left side of the precordium moves out. (2) As both ventricles eject, there is a large inward motion of the right parasternal region. This is apparently produced by rapid descent of the closed tricuspid valve. (3) The expansion of the aorta produces an outward motion in the suprasternal notch, and sometimes in the upper intercostal spaces. The analogous movements in the dog are the respective rise and fall in the aortic and ventricular pressure velocity curves and a sharp dip in the right atrial velocity record. B. During the rapid phase of the carotid upstroke: (1) The volume change of ejection causes large inward motion of the left precordial and epigastric areas. (2) Outward movement of the upper right parasternal region occurs. This is apparently due to bulge of the tricuspid valve, which is shown in dogs by an ascent of the atrial pressure velocity tracing. (3) In dogs the aortic velocity record, having passed its peak, shows a small upstroke which is possibly an artifact, but which may be due to elastic rebound. A similar motion has not been seen regularly in tracings from human subjects. C. During reduced ejection: (1) A large upstroke in the region over the right atrium, and a much smaller outward movement (or diminished inward deflection) in the left precordial area, is ascribed to atrial filling. (2) An outward motion of the epigastrium, and sometimes of the lower precordium, occurs. This is probably related to descent of the mitral annulus, since the left atrial velocity record of the dogs shows a downstroke at an approximately corresponding time. (3) The terminal precordial systolic movements are somewhat variable but usually include inward motion (further decrease in ventricular volume) of the left precordial and epigastric areas. (4) Since blood leaves the aorta more rapidly than it enters, the tracing from the suprasternal notch moves inward. The pressure velocity tracings from the ventricles and from the great arteries of the dogs show an upstroke as the phase of reduced ejection begins. This is ascribed to the rise in pressure which results from a decrease in volume when fiber tension is relatively constant (Laplace effect). During ejection, certain changes in shape occur and appear to cause stretch of some of the fibers. The extent to which such secondary length may influence the terminal contraction of these fibers is uncertain.