http://repub.eur.nl/res/aut/1849/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/4587/ 1994-01-01T00:00:00Z Long-term changes in vasocontractility were examined in 23 coronary segments from 20 patients with variant angina using computer-based quantitative coronary angiography and ergonovine provocation tests repeated at an interval of 42 +/- 14 months. Measurements of vasospasticity at the sites of fixed stenoses were compared with values predicted by an elementary geometric theory based on the assumption that the cross-sectional area of a vessel wall is constant regardless of its state of vasoconstriction. While all patients were symptomatic initially, only 11 remained symptomatic at follow-up. At the initial provocation test, the response was correctly predicted in four segments, was lower than expected in one, and was stronger in 18. At follow-up, only one of the four segments in which the response had been initially predicted correctly again showed the predicted response and the remaining three showed a response weaker than expected; the one segment which was initially hypocontractile remained hypocontractile at follow-up; and of the 18 segments which were initially hypercontractile, 12 exhibited hypercontractility again, four had the predicted value and the remaining two showed hypocontractility. In only one of 23 segments did the geometric theory predict the behaviour of vasospasticity at the site of fixed stenosis on both tests. Vasospastic responsiveness is a dynamic process demonstrating temporal variability and is not directly predicted by geometric theory. http://repub.eur.nl/res/pub/4506/ 1993-01-01T00:00:00Z In vitro and animal experiments have shown that the severity of coronary stenoses can be assessed using the continuity equation if the maximal blood flow velocity of the stenotic jet is measured. The large diameter and the low range of velocities measurable without frequency aliasing with the conventional intracoronary Doppler catheters precluded the clinical application of this method for hemodynamically significant coronary stenoses in humans. This article reports the results obtained using a 12 MHz steerable angioplasty guidewire in a consecutive series of 52 patients undergoing percutaneous coronary angioplasty (61 coronary stenoses). The ratio between coronary flow velocity in a reference segment and in the stenosis was used to estimate the percent cross-sectional area stenosis. A Doppler recording suitable for quantitation was obtained in the stenotic segment in only 10 of 61 arteries (16%). The time-averaged peak velocity increased from 15 +/- 5 to 115 +/- 26 cm/sec from the reference normal segment to the stenosis. Volumetric coronary flow calculated from the product of mean flow velocity and cross-sectional area was similar in the stenosis and in the reference segment (33.2 +/- 14.9 vs 33.5 +/- 17.0 mL/min, respectively, difference not significant). The percent cross-sectional area stenosis and minimal luminal cross-sectional area derived from the Doppler velocity measurements using the continuity equation and calculated with quantitative angiography were also similar (Doppler, 86.7 +/- 5.1% and 1.00 +/- 0.48 mm2; quantitative angiography, 85.9 +/- 7.9% and 1.02 +/- 0.50 mm2).(ABSTRACT TRUNCATED AT 250 WORDS) http://repub.eur.nl/res/pub/4507/ 1993-01-01T00:00:00Z The use of miniaturized pressure and velocity sensors mounted on angioplasty guidewires allows the simultaneous measurement of coronary blood flow velocity and transstenotic pressure gradient, 2 parameters that, combined, should perfectly characterize stenosis hemodynamics. The aim of this article is assessment of the changes in coronary blood flow velocity observed with a Doppler-tipped angioplasty guidewire in 35 patients undergoing balloon angioplasty. We also report our initial experience in 16 patients with the combined use of sensor-tip pressure and Doppler guidewires, and we discuss the application of new methodologic approaches for the study of the coronary circulation allowed by these techniques, such as the instantaneous assessment of the flow velocity/pressure and pressure gradient/flow velocity relations. Before and after angioplasty, flow velocity measurements were obtained distal to the stenosis, both in baseline conditions and after intracoronary injection of 8-12.5 mg of papaverine. The Doppler guidewire was left in place during the dilation procedure and the Doppler signal was continuously recorded during balloon inflation and after deflation to monitor the development of collateral flow, the restoration of flow after balloon deflation, the phase of postocclusive reactive hyperemia, and, incidently, the development of flow-limiting complications. Merits and pitfalls of several flow velocity parameters (average peak velocity, coronary flow velocity reserve, diastolic/systolic velocity ratio), as well as of parameters derived from the combination of pressure and velocity measurements (transstenotic pressure gradient/flow velocity relation and instantaneous diastolic hyperemic flow velocity/pressure relation) were evaluated in 35 patients with, and 37 without, significant coronary stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)