Degree Of Lumen Narrowing Research Articles

Intimal Hyperplasia, Arterial Remodeling, and Restenosis: An Overview

The occurrence of restenosis due to intimal hyperplasia and arterial remodeling remains an unsolved problem after cardiovascular interventions. All forms of reconstructions, whether interventional or surgical, cause injury to the vessel wall, resulting in a wound healing response. In situations in which it becomes exaggerated it leads to restenosis. This injury may involve the development of intimal hyperplasia (IH), which is defined as the migration and proliferation of smooth muscle cells (SMC) into the subintimal space of the vessel. There is subsequent SMC production and deposition of matrix with some degree of lumen narrowing. This complex process has multiple factors that have been implicated to initiate and promulgate it, including those of the immune system, coagulation system, and local paracrine growth factors and cytokines. Recent studies have shown that, besides IH through its production of a physical mass that encroaches on the lumen, the changes in the artery wall geometry, defined as arteri...

Role of beta1 and beta3 integrins in human smooth muscle cell adhesion to and contraction of fibrin clots in vitro.

The degree of lumen narrowing in advanced lesions correlates poorly with the amount of intimal mass accumulated in the atherosclerotic plaque. As an alternate mechanism of stenosis, we propose that human smooth muscle cells bind to fibrin deposited in the matrix and exert contractile forces to cause a narrowing of the lumen. In the present study we demonstrated in vitro that human newborn aortic smooth muscle cell lines can contract and adhere to fibrin clots composed of either fibronectin-depleted plasma ("plasma") or recombinant fibrin. By using neutralizing antibodies and RGD peptides, we showed that members of the integrin family mediated the interaction between human newborn smooth muscle cells and fibrin. Neutralizing antibodies against the integrin alphavbeta3 (c7E3 Fab and LM609) did not inhibit either plasma clot contraction or recombinant fibrin clot contraction by human newborn smooth muscle cells. In contrast, antibodies against alpha5, beta1, and alpha5/beta1 inhibited contraction of clots composed of either plasma or recombinant fibrin. Anti-alphavbeta3, anti-alphav, anti-alpha5, anti-beta1, and anti-alpha5beta1 antibodies inhibited human newborn smooth muscle cell adhesion to plasma clots; however, only anti-alpha5, anti-beta1, and anti-alpha5beta1 antibodies significantly inhibited adhesion to recombinant fibrin. While the linear RGD peptides had no effect, the cyclic peptide penRGD inhibited adhesion to plasma clots and recombinant fibrin. However, it did not block contraction of recombinant fibrin clots. These results suggest that during the interaction of human newborn smooth muscle cell lines with fibrin, alpha5beta1 plays a significant role. This interaction is of potential interest as a target for efforts to block vascular contraction.

An Experimental Manometric Study Simulating Upper Esophageal Sphincter Narrowing

Elevated intrabolus pressure above a pharyngeal narrowing has been postulated as an important finding in patients with cricopharyngeal bars. To elucidate the significance of intrabolus pressure around lumen narrowings in the pharynx, intraluminal pressure characteristics were evaluated in a laboratory model simulating upper esophageal sphincter narrowing. Intraluminal solid-state manometry was performed in an experimental model in which variable narrowing was created in an expandable balloon simulating the pharyngeal walls. Intrabolus pressure was dependent on the position of the manometric sensor, degree of lumen narrowing, bolus volume, flow rate, and fluid viscosity. Elevated intrabolus pressure is an important finding. Intrabolus pressure is dependent on many parameters, and hence, is difficult to evaluate. If results found with this model hold true in patients, manometric sensor positioning is crucial, and concurrent fluoroscopy is highly recommended to achieve a standardized manometric technique in pharyngeal manometry.

Correlation of peak Doppler frequency with lumen narrowing in carotid stenosis.

The peak Doppler-shifted frequency and degree of lumen narrowing were compared in 75 cervical carotid stenoses. Peak frequency was not found to precisely indicate severity of stenosis, but it was possible to divide stenoses into four ranges of severity on the basis of peak frequency. Peak frequencies of less than 5 KHz, in most instances, indicated stenoses of less than 50% decrease in lumen area. Frequencies from 5 to 8 KHz were generally associated with stenoses of 50-75% decrease in lumen area, and frequencies of 8-12 KHz were most often associated with stenoses of 75-90% decrease in area. Frequencies greater than 12 KHz almost invariably occurred in very severe lesions of greater than 90% decrease in lumen area (greater than 70% decrease in diameter). The use of peak frequency as an indicator of severity of stenosis, while not specific, is felt to be of considerable clinical benefit as it provides a more quantitative evaluation of stenosis than auditory assessment of Doppler frequencies.