VALUES AND LIMITATIONS OF TRANSSTENOTIC PRESSURE-GRADIENTS MEASURED DURING PERCUTANEOUS CORONARY ANGIOPLASTY

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  • 1 January 1985
    • journal article
    • research article
    • Vol. 10  (6) , 337-342
Abstract
The pressure gradient across coronary stenoses is measured routinely during angioplasty. Due to the finite size of the angioplasty catheter within the stenotic cross section, the remaining luminal area is further reduced and the transstenotic gradient may be overestimating the "true" pressure drop. This "true" pressure gradient can be approximate from the mean coronary blood flow and the stenosis geometry from theoretical models. Goal of this study was to assess the values and limitations of the in vivo measurements of the pressure gradient versus the calculated values. Therefore, flow in the great cardiac vein was measured in 13 patients before and/or after angioplasty of a proximal left anterior descending stenosis, not filled by collaterals. The Poiseuille and turbulent contributions to flow resistance were determined from stenosis geometry assessed by quantittive coronary angiography. A fourfold increase in the luminal area (from 0.7 mm2 pre- to 2.8 mm2 post angioplasty) was associated with a fourfold decrease in the in vivo measured transstenotic gradient (from 59 mm Hg pre- to 13 mm Hg post angioplsty). The occlusion area and the measured gradient were linearly correlated: gradient = 69 - 17 .cntdot. occlusion area (r = 0.76). However, as expected, the transtenotic gradient systematically overestimated the theoretical gradient calculated from the laws of fluid dynamics. A nonlinear relation was found between the calculated gradient P and the occlusion area As: P = 15 .cntdot. As-2 (r = 0.87). Conclusion: The present study shows clearly that the absolute value of the transstenotic gradients obtained during angioplasty do not reflect accurately the flow resistance.