A Novel Model of Balloon Angioplasty Injury in Rat Arteriovenous Fistula

Vessel Wall Histologic Changes in a Porcine Model of Arteriovenous Fistula Stenosis Treated with Percutaneous Transluminal Angioplasty

PURPOSE

To describe the immunohistologic changes in arteriovenous fistula stenosis treated using plain old balloon angioplasty (POBA) versus paclitaxel drug-coated balloons (DCBs).

MATERIALS AND METHODS

Castrated male Yorkshire pigs (n = 12) 4-5 months old had chronic kidney disease induced with renal artery embolization. Twenty-eight days later, a side-to-end anastomosis was created between the left common carotid artery and ipsilateral external jugular vein. Four weeks later, a juxta-anastomotic stenosis was treated with balloon angioplasty (percutaneous transluminal angioplasty [PTA]) or DCB, and animals were euthanized at 4 (POBA [n = 6]) and 42 days (POBA [n = 3] or DCB [n = 3]) for histomorphometric analysis with immunohistochemical staining for CD68 (macrophages), FSP-1 (fibroblasts), α-smooth muscle cell (SMC) actin, CD-31 (endothelial), proliferation (Ki-67), and apoptosis (terminal deoxynucleotidyl transferase dUTP nick end labeling [TUNEL]).

RESULTS

Two animals died at 14 and 28 days after PTA. There was a significant increase in the lumen (P = .0431), neointima (P = .0156 at Day (D) 4 and P < .001 at D42), and neointima/media + adventitia (N/M + A) ratio (P = .0061 at D4 and P = .0032 at D42). DCB-treated vessels showed a significant decrease in the N/M + A ratio (P = .0386) and cell density in the intima (P = .0113) compared with those treated with POBA. Endothelial cells were significantly increased at 4 days (P = .0034) and 42 days (P = .012), macrophages were significantly increased at 14 days (P = .0094), fibroblasts were significantly increased at 4 days (P = .0025) and 42 days (P < .001), and SMCs were significantly increased at 28 days (P = .004). Ki-67 staining peaked at 28 days (P = .0018), and TUNEL staining decreased at 4 days (P = .0012), 14 days (P = .0062), and 42 days (P = .04).

CONCLUSIONS

After PTA, the lumen vessel area increases with fibroblast and SMCs peaking at 4, followed by macrophages, SMCs, and proliferation.

Development of a Porcine Model of Arteriovenous Fistula Venous Stenosis Treated with Percutaneous Transluminal Angioplasty

PURPOSE

To develop a porcine model for arteriovenous fistula (AVF) venous stenosis (VS) treated with percutaneous transluminal angioplasty (PTA), and to compare outcomes of plain ordinary balloon angioplasty (POBA) to paclitaxel drug-coated balloon (DCB) angioplasty.

MATERIALS AND METHODS

Twelve castrated male Yorkshire pigs (4-5 months, 35-45 kg) underwent renal artery embolization to induce chronic kidney disease (CKD). Twenty-eight days later, AVF was created by anastomosing the left external jugular vein to left common carotid artery. The pigs were divided into a pilot group (n = 6) for optimizing the AVF technique (euthanized at Day 4) and a definitive group (n = 6) for validating PTA outcomes (euthanized at Day 42). Stenosis developed at juxta-anastomosis 28 days later and was treated with POBA (pilot group, n = 6; definitive group, n = 3) or DCB (definitive group only, n = 3). The definitive group underwent biweekly 4-dimensional flow magnetic resonance (MR) imaging.

RESULTS

All animals developed CKD, with significant increases in the levels of blood urea nitrogen (increase of median from 2.6 to 3.2 mmol/L; P < .001) and creatinine (increase of median from 10 to 187 μmol/L, P < .001). In the pilot group, 1 animal had an infected fistula, and AVF patency was 1/5. In the definitive group, the patency was 5/6 because the AVF technique was modified by resecting the sternomastoid muscle and increasing the spatulation. At Day 42 after PTA, the DCB-treated AVF outflow vein showed increasing but statistically insignificant blood flow compared with POBA (DCB, 209.8 mm2 ± 64.4, vs POBA, 170.9 mm2 ± 95.5; P = .934).

CONCLUSIONS

A porcine model of AVF VS treated with PTA was developed, with blood flow trends favoring DCB over POBA.

Evolving Strategies for Use of Phytochemicals in Prevention and Long-Term Management of Cardiovascular Diseases (CVD)

This report describes major pathomechanisms of disease in which the dysregulation of host inflammatory processes is a major factor, with cardiovascular disease (CVD) as a primary model, and reviews strategies for countermeasures based on synergistic interaction between various agents, including drugs and generally regarded as safe (GRAS) natural medical material (NMM), such as Ginkgo biloba, spice phytochemicals, and fruit seed flavonoids. The 15 well-defined CVD classes are explored with particular emphasis on the extent to which oxidative stressors and associated ischemia-reperfusion tissue injury contribute to major symptoms. The four major categories of pharmaceutical agents used for the prevention of and therapy for CVD: statins, beta blockers (β-blockers), blood thinners (anticoagulants), and aspirin, are presented along with their adverse effects. Analyses of major cellular and molecular features of drug- and NMM-mediated cardioprotective processes are provided in the context of their development for human clinical application. Future directions of the evolving research described here will be particularly focused on the characterization and manipulation of calcium- and calcineurin-mediated cascades of signaling from cell surface receptors on cardiovascular and immune cells to the nucleus, with the emergence of both protective and pathological epigenetic features that may be modulated by synergistically-acting combinations of drugs and phytochemicals in which phytochemicals interact with cells to promote signaling that reduces the effective dosage and thus (often) toxicity of drugs.

The rodent models of arteriovenous fistula

Arteriovenous fistulas (AVFs) have long been used as dialysis access in patients with end-stage renal disease; however, their maturation and long-term patency still fall short of clinical needs. Rodent models are irreplaceable to facilitate the study of mechanisms and provide reliable insights into clinical problems. The ideal rodent AVF model recapitulates the major features and pathology of human disease as closely as possible, and pre-induction of the uremic milieu is an important addition to AVF failure studies. Herein, we review different surgical methods used so far to create AVF in rodents, including surgical suturing, needle puncture, and the cuff technique. We also summarize commonly used evaluations after AVF placement. The aim was to provide recent advances and ideas for better selection and induction of rodent AVF models. At the same time, further improvements in the models and a deeper understanding of AVF failure mechanisms are expected.

Effects of arteriovenous fistulas and central venous catheters on the cardiac function and prognosis of patients on maintenance hemodialysis

Objective

To investigate the effects of arteriovenous fistulas (AVFs) and central venous catheters (CVCs) on the left ventricular function (LVF) and prognosis of maintenance hemodialysis (MHD) patients.

Methods

This retrospective cohort study included 270 patients (139 with AVF and 131 with CVC) undergoing dialysis with newly established vascular access in the blood purification center of Nanhua hospital, University of South China, from January 2019 to April 2021. Dialysis efficiencies, LVF indexes, and one-year prognoses were compared.

Results

At six and twelve months after the establishment of vascular access, the mean urea clearances (Kt/V) and urea reduction ratio (URR) between the AVF- and the CVC-group were similar (P>0.05). The mean LVF values between the two groups were also similar before the establishment of vascular access (P>0.05), but the mean values of left ventricular end diastolic diameter (LVEDd), interventricular septal thickness (IVSTd), and left ventricular posterior wall thickness (LVPWT) in the AVF-group were higher than those in the CVC-group one year later, and mean early (E) and late (A) diastolic mitral velocities, E/A, and ejection fraction (EF) were lower than those in the CVC-group (P<0.05). The incidence of left ventricular hypertrophy and systolic dysfunction in the AVF-group was higher than that in the CVC-group (P<0.05). The hospitalization rate of AVF-group (23.02%) was lower than that of the CVC-group (49.61%) (P<0.05).

Conclusion

Both AVF and CVC can achieve appropriate dialysis effects in MHD patients. AVF has a negative impact on cardiac function while CVC has a high hospitalization rate.

Experimental murine arteriovenous fistula model to study restenosis after transluminal angioplasty

Percutaneous transluminal angioplasty (PTA) is a very common interventional treatment for treating stenosis in arteriovenous fistula (AVF) used for hemodialysis vascular access. Restenosis occurs after PTA, resulting in vascular lumen loss and a decrease in blood flow. Experimental animal models have been developed to study the pathogenesis of stenosis, but there is no restenosis model after PTA of stenotic AVF in mice. Here, we describe the creation of a murine model of restenosis after angioplasty of a stenosis in an AVF. The murine restenosis model has several advantages, including the rapid development of restenotic lesions in the vessel after angioplasty and the potential to evaluate endovascular and perivascular therapeutics for treating restenosis. The protocol includes a detailed description of the partial nephrectomy procedure to induce chronic kidney disease, the AVF procedure for development of de novo stenosis and the angioplasty treatment associated with progression of restenosis. We monitored the angioplasty-treated vessel for vascular patency and hemodynamic changes for a period of 28 d using ultrasound. Vessels were collected at different time points and processed for histological analysis and immunostaining. This angioplasty model, which can be performed with basic microvascular surgery skills, could be used to identify potential endovascular and perivascular therapies to reduce restenosis after angioplasty procedures.