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Distal Anastomotic Intimal Hyperplasia: Histocytomorphology, Pathophysiology, Etiology, and Prevention
1Pendelton Memorial Methodist Hospital, New Orleans, Louisiana
Insights
Distal anastomotic intimal hyperplasia (DAIH) causes late graft occlusion. Controlling vascular myoblast activity, not compliance mismatch, prevents DAIH. Specific heparin fractions show promise in treatment.
Area of Science:
- Vascular surgery
- Biomedical engineering
- Pathology
Background:
- Late graft occlusion is a significant clinical issue, often linked to distal anastomotic intimal hyperplasia (DAIH).
- DAIH affects various graft types, including nonautogenous bypasses, and is a key factor in graft failure.
- Understanding the mechanisms and location of DAIH is crucial for developing effective prevention and treatment strategies.
Purpose of the Study:
- To investigate the role of compliance mismatch and anastomosis configuration in DAIH development.
- To elucidate the cellular and molecular cascade leading to DAIH formation.
- To evaluate the efficacy of pharmacologic agents in controlling DAIH.
Main Methods:
- Canine models were used to study DAIH in end-to-side versus end-to-end anastomoses.
- Compliance mismatch effects were assessed.
- Pharmacologic agents targeting vascular myoblasts were employed.
- Experimental models confirmed the antiproliferative effects of a specific heparin fraction.
Main Results:
- DAIH predominantly occurred in end-to-side anastomoses, not in side-matching end-to-end configurations.
- Compliance mismatch was found to enhance, not cause, DAIH pathogenesis.
- Pharmacologic modulation of vascular myoblast activity successfully attenuated DAIH development and progression.
- A heparin fraction with antiproliferative effects on myoblasts demonstrated success in controlling DAIH.
Conclusions:
- DAIH formation is primarily driven by vascular myoblast proliferation and matrix synthesis, triggered by endothelial cell changes at the anastomosis.
- Controlling vascular myoblast activity is essential for preventing DAIH and late graft failure.
- Pharmacologic inactivation of myoblasts offers a targeted approach to manage DAIH, as exemplified by the successful use of an antiproliferative heparin fraction.
Abstract:
The ubiquitous relationship of late graft occlusion, particularly the nonautogenous bypasses and distal anastomotic intimal hyperplasia (DAIH), has been extensively investigated. After having established the specific location of DAIH in human autogenous, biologic and prosthetic late graft occlusion, canine models were designed to elucidate the role of compliance mismatch between graft and the host artery and the configuration of the distal end to side versus end to end anastomosis using autogenous artery. DAIH occurred in all end to side anastomosis but not in side matching end to end anastomosis. Compliance mismatched is not the cause of DAIH development, but it enhances the pathogenesis. Further study using pharmacologic agents to modulate the activities of vascular myoblasts was successful in attenuating DAIH development and progression. Since DAIH occurs through a cascade of events initiated by endothelial lifting of the overlapping processes at the gap junction to allow blood borne elements to enter the subendothelial space, then incites myoblast proliferation and matrix synthesis leading to DAIH formation at the heel and toe where oscillatory flow exists. Control of myoblast activity is needed on a permanent basis to prevent DAIH development and progression. Cessation of treatment allows resurgence of DAIH biogenesis. Direct regulation of vascular myoblast activity preclude the need of inhibiting other source of stimuli that increases as our knowledge of the subject grows. Without the participation of myoblast, there will be no DAIH irrespective of the potency and numbers of enzymatic, hormonal, or mechanical inciting factors. DAIH is a byproduct of oscillatory flow at the heel and the toe which enable blood borne elements to enter subendothelial space via the gap junction subsequent to lifting of endothelial cell overlapping processes. Pharmacologic control aiming at inactivating the myoblast in proliferation and matrix synthesis is a logical mode to control DAIH formation and late graft failure. Our experimental models confirm the success in controlling DAIH using heparin fraction that lack the anticoagulant yet is active in antiproliferative effect on myoblasts.