PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY CATHETERS VERSUS FLUID-FILLED PRESSURE MONITORING GUIDEWIRES FOR CORONARY PRESSURE MEASUREMENTS AND CORRELATION WITH QUANTITATIVE CORONARY ANGIOGRAPHY

The functional significance of a coronary stenosis can be assessed by measuring the translesional pressure gradient. Thirty-four patients were studied in the setting of percutaneous transluminal coronary angioplasty (PTCA) to evaluate the clinical relevance of the pressure gradient measurements by means of a PTCA balloon catheter. Both before and after PTCA, the mean pressure gradient across the stenosis was measured by means of a newly developed, 0.015-inch pressure-mow itoring guidewire, first with only the wire across the stenosis (DELTAP(W), considered as the actual gradient), and second with the deflated balloon catheter advanced over the wire in the stenosis (DELTAP(b)). Pressure gradients were correlated with quantitative coronary angiography of the stenotic segment. Before PTCA, mean DELTAP(b) was larger than DELTAP(W) (62 +/- 14 vs 30 +/- 20 mm Hg; p < 0.01). After PTCA, DELTAP(b) remained systematically higher than DELTAP(W) (23 +/- 14 vs 3 +/- S mm Hg; p < 0.01), despite a significant reduction of percent area stenosis from 84 +/9 to 46 +/- 17%, and an increase in minimal obstruction area from 0.98 +/- 0.48 to 3.49 +/- 1.32 mm2. A significant correlation was found between DELTAP(W) and percent area stenosis (r2 = 0.66), with a marked increase after percent area stenosis reached 80%. The correlation between DELTAP(b) and percent area stenosis was weaker (r2 = 0.53), the scatter of the data was larger, and the inflection point of the curve was shifted toward less severe degrees of stenosis severity. The relation between the percent overestimation produced by the presence of the PTCA balloon catheter and either DELTAP(W) or the ratio between catheter and obstruction cross-sectional area suggested that in intermediate lesions and post-PTCA segments, the overestimation was poorly predictable. Thus, the presence of a PTCA catheter through a coronary stenosis causes a systematic and unpredictable overestimation of the actual pressure gradient. Even after FTCA, the pressure gradient measured with the balloon catheter does not reflect the hemodynamic significance of the dilated segment.