Centered endovascular irradiation to prevent postangioplasty restenosis of arteriovenous fistula in hemodialysis patients; Results of a feasibility study

Therapeutic strategies based on non-ionizing radiation to prevent venous neointimal hyperplasia: the relevance for stenosed arteriovenous fistula, and the role of vascular compliance

We have reviewed the development and current status of therapies based on exposure to non-ionizing radiation (with a photon energy less than 10 eV) aimed at suppressing the venous neointimal hyperplasia, and consequentially at avoiding stenosis in arteriovenous grafts. Due to the drawbacks associated with the medical use of ionizing radiation, prominently the radiation-induced cardiovascular disease, the availability of procedures using non-ionizing radiation is becoming a noteworthy objective for the current research. Further, the focus of the review was the use of such procedures for improving the vascular access function and assuring the clinical success of arteriovenous fistulae in hemodialysis patients. Following a brief discussion of the physical principles underlying radiotherapy, the current methods based on non-ionizing radiation, either in use or under development, were described in detail. There are currently five such techniques, including photodynamic therapy (PDT), far-infrared therapy, photochemical tissue passivation (PTP), Alucent vascular scaffolding, and adventitial photocrosslinking. The last three are contingent on the mechanical stiffening achievable by the exogenous photochemical crosslinking of tissular collagen, a process that leads to the decrease of venous compliance. As there are conflicting opinions on the role of compliance mismatch between arterial and venous conduits in a graft, this aspect was also considered in our review.

A single treatment, using Far Infrared light improves blood flow conditions in arteriovenous fistula

BACKGROUND

A native arteriovenous fistula (AVF) is recommended for angio access in patients on chronic hemodialysis (HD). Fistula patency has been improved by exposure to Far Infrared light (FIR).

OBJECTIVE

To investigate whether a single FIR treatment could alter blood velocity, AVF diameter or inflammatory markers.

METHODS

Thirty patients with a native AVF in the forearm were included. Each patient was his/her own control. Ultrasound (US) examinations were performed before and after a single FIR treatment.

RESULTS

A single FIR treatment resulted in a significant increase in blood velocity over the AV fistula from a mean of 2.1 ± 1.0 m/s to 2.3 ± 1.0 m/s (p = 0.02). The diameter of the arterialized vein became wider; 0,72 cm ± 0.02 to 0,80 cm ± 0.02, (p = 0.006). The increase in fistula blood velocity correlated positively with base line serum- urate p = 0.004) and the increase in venous diameter with the base line plasma orosomucoid concentration (p = 0.005).

CONCLUSIONS

This study shows that a single FIR treatment significantly increased AVF blood velocity and vein diameter. Thus, one FIR treatment can help maturation of AVF in the early postoperative course.

Neointimal hyperplasia associated with synthetic hemodialysis grafts

Stenosis is a major cause of failure of hemodialysis vascular grafts and is primarily caused by neointimal hyperplasia (NH) at the anastomoses. The objective of this article is to provide a scientific review of the biology underlying this disorder and a critical review of the state-of-the-art investigational preventive strategies in order to stimulate further research in this exciting area. The histology of the NH shows myofibroblasts (that are probably derived from adventitial fibroblasts), extracellular matrices, pro-inflammatory cells including foreign-body giant cells, a variety of growth factors and cytokines, and neovasculature. The contributing factors of the pathogenesis of NH include surgical trauma, bioincompatibility of the synthetic graft, and the various mechanical stresses that result from luminal hypertension and compliance mismatch between the vessel wall and graft. These mechanical stimuli are focal in nature and may have a significant influence on the preferential localization of the NH. Novel mechanical graft designs and local drug delivery strategies show promise in animal models in preventing graft NH development. Successful prevention of graft stenosis would provide a superior alternative to the native fistula as hemodialysis vascular access.

Socioeconomic relevance of selected treatment strategies in patients with chronic heart failure

More than 2.8% of the population in the USA suffer from chronic heart failure, a condition that primarily afflicts people above the age of 60 years, and results in major expenses for social and health care of affected patients, their caregivers and families. The mainstay of treatment is drug therapy, complemented by comprehensive rehabilitation, invasive procedures, palliative treatment and monitoring. While sufficient health economic evidence exists on the cost-effectiveness of certain standard drugs, such as angiotensin converting enzyme inhibitors or beta-blockers, little or no information exists on the cost effectivty of diuretics or aldosterone antagonists. Recently, introduced treatment strategies such as ventricular assistance devices or telemonitoring have yet to be evaluated for their cost-effectiveness in terms of risk of hospitalization, life expectancy and quality of life. With respect to the aging population and the drastically increasing costs of healthcare for heart failure patients, the goal is a more conscious and cost-effective resource allocation. This can help reduce the incidence of over and under treatment, diminish side effects and consequently improve symptoms, quality of life and life expectancy in the affected population. Further clinical trials and health economic analyses are necessary to optimize recommendations for healthcare of patients with chronic heart failure.