Assessment of coronary compensatory enlargement by three-dimensional intravascular ultrasound

Several techniques have been used to demonstrate that human arteries respon d to atherosclerosis by increasing their total arterial area to prevent a d ecrease in blood flow. Three-dimensional reconstructions of coronary arteri es can document this compensatory response accurately and specifically. Sev en human coronary arteries were reconstructed using intravascular ultrasoun d and biplane angiography, and vessel geometries were quantified. In all se ven vessels, as plaque area increased, overall vessel area increased (R = 0 .986, 0.933, 0.984, 0.678, 0.763, 0.963, and 0.830), but luminal cross-sect ional area did not significantly decrease. Focal compensatory enlargement w as identified in each vessel, and in some cases this response appeared to o ccur until the vessel was 65% occluded. Luminal enlargement near the proxim al ends was attributed to the natural taper of the vessel. The semi-automat ed, three-dimensional segmentation technique used in this study allows repr oducible quantification, as there is no subjective manual tracing involved. Following the intravascular ultrasound transducer in time and space with b iplane angiography allows for accurate reconstruction with or without autom ated pullback devices. Information on the rate of change of vessel measurem ents is also presented, which, when combined with visualization of accurate 3D geometry, provides a unique assessment of coronary compensatory enlarge ment. This reconstruction technique can be applied in a clinical environmen t with no major modification.