Assessment of the mechanical properties of coronary arteries using intravascular ultrasound: an in vivo study

The pressure-area relation of coronary arteries provides important informat ion about the mechanical properties of these vessels. In human subjects met hodological limitations have precluded measurement of instantaneous complia nce and coronary stress in vivo. The purpose of this study was to assess a new method for measuring instantaneous values of coronary artery compliance and wall stress utilizing simultaneously acquired pressure and intravascul ar ultrasound measurements of vessel area. Ten subjects with coronary arter y disease had intravascular ultrasound studies of the proximal left anterio r descending or circumflex coronary arteries. Coronary luminal area was mea sured with a 30-MHz (3F or 3.5F) intravascular ultrasound catheter and simu ltaneous coronary pressure measured with a 2F micromanometer-tipped cathete r. Using this technique the nonlinear pressure-area relation and mean circu mferential wall stress were determined over the physiological pressure rang e. Coronary artery compliance at 100 mmHg ranged from 0.010 to 0.052 mm(2)/ mmHg (mean +/- SD, 0.020 +/- 0.012 mm(2)/mmHg). Peak systolic circumferenti al stress ranged from 0.52 to 2.03 x 10(6) dyn/cm(2) (1.09 +/- 0.42 x 10(6) dyn/cm(2)). This study describes a new method of determining coronary arte ry mechanical properties over the physiological pressure range. This techni que may be useful in further studies of coronary artery mechanics.