Coronary stent implantation in patients with postangioplasty restenosis normalized poststenotic myocardial perfusion immediately as a result of a larger postprocedural lumen and a more pronounced inhibition of elastic recoil. After 6 months this benefit was sustained despite progressive lumen loss.
A system for computerized processing of video image series was utilized for the real-time digitization of arteriograms. There were 256 x 256 picture elements (pixels) per image with a resolution of 256 gray levels. Temporal changes in x-ray absorption at each pixel as induced by contrast media were computed for the extraction of regional blood flow parameters. Four steps of processing included: (a) vascular masking, (b) time parameter extraction, (c) segmentation of vessels, and (d) segmental volume and flow determinations. The results were displayed pictorially as angiographic parameter images. Measurement of the regional blood flow was tested at the abdominal arteries in nine pigs. Flow distribution values at the renal and iliac arteries were accurate within +/- 5% of the total abdominal aortic flow. The method may also be applicable to quantitative circulatory studies of the cerebral, pulmonary, and possibly, coronary arteries.
A new balloon catheter was developed for continuous perfusion of coronary arteries during angioplasty (CPC catheter). Steerable Grüntzig balloon catheters (3.7 mm) with two lumina were formed. The first lumen was used for balloon inflation. Side holes to the second lumen proximally and distally to the balloon were created for coronary perfusion even during inflation phase. At a perfusion pressure of 120 mmHg, a flow rate of 63 +/- 3 ml/min with 0.9% saline and 43 +/- 1 ml/min with plasma expander were measured. In experiments on five dogs, dilation time until appearance of signs of ischemia could be prolonged in three of five dogs from 30 to 40 s, 120 to 203 s, and 180 to 420 s comparing conventional and CPC balloon catheters. In 11 patients with proximal lesions, dilation time could be increased from 39.5 +/- 23.9 s to 81.1 +/- 36.3 s (p less than 0.01) until appearance of angina pectoris. ST segment changes were observed in 10/11 patients using conventional catheters. Using CPC catheters, no ST segment changes were observed in four patients; time until appearance of ST segment changes was delayed in the other seven patients. The CPC catheter seems to be an alternative catheter in proximal lesions of the left and right coronary artery, allowing the possibility of prolonged dilation and increased safety to the patient. In case of dissection or perforation, the CPC catheter can be used for perfusion of the distal part of the coronary vessel until emergency bypass surgery.
To identify risk factors for restenosis, we evaluated data in 473 patients with single-vessel percutaneous transluminal coronary angioplasty (PTCA) and control angiography after 6 months. Restenosis, defined as (1) loss greater than 50% of the initial gain, and (2) stenosis greater than 50% was found in 138 patients (29.2%). Univariate analysis revealed eight factors related to restenosis: (1) duration of symptoms less than 1 month (P = 0.005), (2) unstable angina (P = 0.004), (3) high-grade stenosis before PTCA (P = 0.014), (4) large residual stenosis after PTCA (P = 0.001), (5) insufficient improvement of stenosis (P = 0.042), (6) prolonged single inflation time (P = 0.017), (7) prolonged total inflation time (P = 0.055), and (8) low inflation pressure (P = 0.028). Multivariate analysis revealed four factors significantly related to restenosis: (1) large residual stenosis after PTCA (P = 0.0001), (2) prolonged single inflation time (P = 0.0047), (3) unstable angina (P = 0.0127), and (4) high-grade stenosis before PTCA (P = 0.0179). Modification of procedural factors might be helpful to reduce the risk of restenosis after successful PTCA.
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