[Noninvasive estimation of pressure gradient in the left ventricular outflow tract: an experimental study]

The relationship between systolic anterior motion of the mitral valve (SAM) and left ventricular outflow pressure gradient (PG) was examined in five dogs with experimentally-produced SAM. A total of 155 heart beats including 29 post-extrasystolic beats with various PG were analyzed. Correlations of PG with the time from the onset of left ventricular ejection to the onset of SAM-septal contact (SSC), SSC divided by ejection time (ET) (SSC/ET), and SSC/ET multiplied by the pre-ejection period (PEP) (PEP X SSC/ET) were obtained. The relation between the natural logarithm of PG (InPG) and SSC/ET was expressed by the linear regression equation: InPG = -5.16X + 5.19, with the correlation coefficient (r) of -0.88 for total 155 beats (r ranged from -0.75 to -0.96 for each dog), and the relation between InPG and PEP X SSC/ET by the formula of InPG = -0.075X + 5.35, with the r of -0.91 for total 155 beats (r ranged from -0.84 to -0.95 for each dog). These results indicated that the time from the onset of aortic ejection to the onset of SAM-septal contact is strongly dependent on the degree of PG.