Abstract

Despite extensive clinical and experimental investigations of venous thrombosis, relatively little is known about the early phases of healing of the venous thrombus. Soon after its discovery heparin has become the most popular agent for the prevention and treatment of venous thrombosis, but there are a number of unanswered questions regarding the most satisfactory treatment for venous thrombosis.

One area of controversy has been the duration of anticoagulation therapy for acute venous thrombosis. If the anticoagulant is discontinued too soon, the thrombus may continue to propagate. Prolonged anticoagulant therapy exposes the patient to the risk of serious hemorrhage. The objective of anticoagulant therapy is complete endothelialization of the surface of an acute thrombus. Further extension is prevented since intact endothelial cells are antithrombotic and clotting elements are shielded from blood interface.

There is a paucity of experimental studies reporting endothelialization of acute venous thrombi. It is the purpose of this study to determine the rate of healing of acute venous thrombi as evidenced by endothelialization, organization and recanalization.

Thrombi were produced by the injection of a sclerosing solution, sodium tetradecyl sulfate, into the isolated venous segments of dogs to injure the intima. After sacrifice at intervals, those venous segments were removed and dilute silver nitrate solution was used to stain intercellular cement substance in the endothelial layer. Hematoxylin-eosin and Gomori's trichrome stains were also employed. Longitudinal and cross sections were made to examine the healing process in venous thrombi at each stage.

A thrombus of relatively uniform size was produced in 38 of 42 venous segments treated with the sclerosing agent. Endothelial growth over a thrombus was evident within five days in most cases and was seen as early as three days in a few specimens. About ten days were required for the entire surface of the thrombus to become covered by new endothelial cells. Organization and recanalization lagged behind endothelialization. By seven days the advancing head of the thrombus showed a moderate degree of organization and some formation of new vascular channels, but the greater part of the thrombus still remained as blood clot. At 21 days the entire thrombus was replaced by new vascularized connective tissue. Although a tiny remnant of organized thrombus was observed in two cases, the others did not show the separation of the overlying unorganized thrombus from the attachment site to the venous wall. Re-establishment of venous flow through thrombi was apparently produced by the development of the vascularization within organizing thrombi. The healing process occurred earlier and was more extensive in the advancing head than in the distal portion.

Canine external jugular or iliac veins in which experimental thrombi were made measured 5-6 mm in diameter. The size of these veins may well be comparable to that of many veins in the human calf. Although the rate of endothelial activity after injury may vary to some extent with the species of animal used, results of this study will be helpful in determining the duration of anticoagulant therapy for acute venous thrombosis.

LLU Discipline

Physiology

Department

Physiology

School

Graduate School

First Advisor

Louis L. Smith

Second Advisor

Raymond D. Gilbert

Third Advisor

Ramon R. Gonzalez

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1980

Date (Title Page)

5-1980

Language

English

Library of Congress/MESH Subject Headings

Thrombophlebitis; Endothelium

Type

Thesis

Page Count

vii; 60

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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