Old Myths, New Concerns: the Long-Term Effects of Ascending Aorta Replacement with Dacron Grafts. Not All That Glitters Is Gold

Abstract

Synthetic grafts are widely used in cardiac and vascular surgery since the mid-1970s. Despite their general good performance, inability of mimicking the elastomechanical characteristics of the native arterial tissue, and the consequent lack of adequate compliance, leads to a cascade of hemodynamic and biological alterations deeply affecting cardiovascular homeostasis. Those concerns have been reconsidered in more contemporaneous surgical and experimental reports which also triggered some research efforts in the tissue engineering field towards the realization of biomimetic arterial surrogates. The present review focuses on the significance of the “compliance mismatch” phenomenon occurring after aortic root or ascending aorta replacement with prosthetic grafts and discusses the clinical reflexes of this state of tissue incompatibility, as the loss of the native elastomechanical properties of the aorta can translate into detrimental effects on the normal efficiency of the aortic root complex with impact in the long-term results of patients undergoing aortic replacement.

Effects of Aortic Graft Implantation on Heart and Downstream Vessels: An Artery is not a Rigid Pipe

“…2 The notion of "compliance mismatch" between the graft and the native aorta has therefore been introduced to explain what emerged as a silent but worrying concept regarding the effects that the presence of a prosthetic graft can induce in native cardiovascular structures, either proximal or distal to the graft, and consequently on the long term outcomes of such prosthetic grafts and their impact on the patient's prognosis. 3,4 Deleterious effects can occur proximal to the graft and are related to the haemodynamic wave reflection of the compliance mismatch on the LV as well as on the aortic valve. Indeed, in physiological conditions, the LV and its afterload are a matched system.…”

“…4 The replacement of the highly elastic native aorta with a non-compliant graft will affect characteristic impedance and pulse wave reflection but above all, the loss of the Windkessel effect and alteration of the pulse wave propagation translate into additional workload for the LV eventually inducing adaptive hypertrophy. 3,5 The prosthetic graft thus generates a significant change in impedance at the interface with the native elastic artery inducing a reduction in ventricular pumping efficiency. 3 Moreover, the loss of diastolic systemic blood pressure augmentation can reduce organ perfusion and particularly coronary flow leading to myocardial ischaemia despite the absence of coronary artery stenosis.…”

Pulmonary autograft in aortic position: is everything known?

“…However, the autograft encased in a straight Dacron prosthetic graft would be dramatically impaired in its pulsatility and compliance. Moreover, we previously demonstrated as Dacron graft and other synthetic polyesters severely impair aortic compliance when used as vascular replacement and elicit a strong inflammatory reaction with significant damage to vessel wall when used a pulmonary artery reinforcement (46,62). From these standpoints, we focused in improving the biomechanical behavior of the reinforced pulmonary artery using a composite biodegradable and auxetic material.…”

Introductory Editorial: Drug-Eluting Stents or Drug-Eluting Grafts? Insights from Proteomic Analysis

“…This development has demolished the obsolete tenets of surgery implying reconstructing organs or part of them with artificial materials. The deeper understanding achieved by modern research has highlighted the limitations and the biological and clinical drawbacks of the long-term coexistence of a foreign material in the body, especially in the cardiovascular system 1. The need to respect the physiological reparative and remodeling processes normally occurring in nature progressively achieved significance in the current research,2,3 demonstrating the necessity to accompany the body’s physiological responses and the activities of tissue regeneration rather than pretending to replace them with “plastic” surrogates.…”