Renal artery revascularization with polytetrafluoroethylene bypass graft

Development of Biocompatible 3D-Printed Artificial Blood Vessels through Multidimensional Approaches

Within the human body, the intricate network of blood vessels plays a pivotal role in transporting nutrients and oxygen and maintaining homeostasis. Bioprinting is an innovative technology with the potential to revolutionize this field by constructing complex multicellular structures. This technique offers the advantage of depositing individual cells, growth factors, and biochemical signals, thereby facilitating the growth of functional blood vessels. Despite the challenges in fabricating vascularized constructs, bioprinting has emerged as an advance in organ engineering. The continuous evolution of bioprinting technology and biomaterial knowledge provides an avenue to overcome the hurdles associated with vascularized tissue fabrication. This article provides an overview of the biofabrication process used to create vascular and vascularized constructs. It delves into the various techniques used in vascular engineering, including extrusion-, droplet-, and laser-based bioprinting methods. Integrating these techniques offers the prospect of crafting artificial blood vessels with remarkable precision and functionality. Therefore, the potential impact of bioprinting in vascular engineering is significant. With technological advances, it holds promise in revolutionizing organ transplantation, tissue engineering, and regenerative medicine. By mimicking the natural complexity of blood vessels, bioprinting brings us one step closer to engineering organs with functional vasculature, ushering in a new era of medical advancement.

Use of Heparin-Bonded Expanded Polytetrafluoroethylene Grafts for Renal Artery Reconstruction

BACKGROUND

The purpose of this study was to analyze our initial experience in renal artery reconstruction with heparin-bonded expanded polytetrafluoroethylene (ePTFE) grafts.

METHODS

The authors retrospectively reviewed the data of consecutive patients who received open renal reconstruction with a heparin-bonded ePTFE graft at our institution between January 2014 and December 2019.

RESULTS

A total of 22 renal reconstructions with a heparin-bonded ePTFE graft were performed in 17 consecutive patients. In all cases, renal reconstruction was a concomitant procedure during surgical or endovascular aortic procedures. Postoperative complications within 30 days were observed in 9 (53%) patients, including acute kidney injury (n = 6), pneumonia (n = 1), retrograde type B aortic dissection (n = 1), and lower limb ischemia (n = 1). The 30-day mortality rate was 0%. In a median follow-up period of 32 (19-39) months, all grafts were patent without re-intervention. Six patients with preoperative stage 2 chronic kidney disease progressed to stage 3 during follow-up. No patient required temporary or permanent hemodialysis. One patient died from intestinal ischemia at 23 months after surgery.

CONCLUSIONS

This study showed that the patency after open renal reconstruction with a heparin-bonded ePTFE graft was excellent, with acceptable renal outcomes, and demonstrates its safety as a concomitant procedure during an aortic procedure. Heparin-bonded ePTFE grafts are a feasible and effective choice for open renal reconstruction in contemporary practice.

Endovascular stent-graft repair of pararenal and type IV thoracoabdominal aortic aneurysms with adjunctive visceral reconstruction

OBJECTIVE

Pararenal and type IV thoracoabdominal aortic aneurysms (TAAA) are not currently considered as indications for endovascular repair given unfavorable neck anatomy or aneurysm involvement of the visceral vessels. Open repair of these aneurysms is associated with significant morbidity and mortality, particularly postoperative renal dysfunction. In selective high-risk patients, debranching of the visceral aorta to improve the proximal neck region can be used to facilitate endovascular exclusion of the aneurysm.

METHODS

Between October 2000 and July 2003, 10 patients were treated with open visceral revascularization and endovascular repair of pararenal and type IV TAAAs at a single institution. Patient demographics and procedural characteristics were obtained from medical records.

RESULTS

Overall 13 visceral bypasses were performed in 10 patients: 6 patients with a single iliorenal bypass, 3 with a hepatorenal bypass, and 1 patient with complete visceral revascularization. Juxtarenal aneurysms occurred in 5 patients (50%), suprarenal aneurysms in 3 patients (30%), and type IV TAAAs in 2 patients (20%). All patients had successful endovascular aneurysm exclusion. Mean follow-up was 8.7 months. There were no perioperative deaths, neurologic deficits coagulopathies, or renal dysfunction. Follow-up spiral computed tomography scans demonstrated patency of all bypass grafts with only one patient requiring a secondary intervention for late type I leak which was sealed with placement of a proximal cuff.

CONCLUSION

These initial results suggest that are similar to infrarenal AAA endovascular repair. This combined approach to repair of pararenal and type IV TAAAs reduces the morbidity and mortality of open repair, and represents an attractive option in high-risk patients while endoluminal technology continues to evolve.

Renovascular hypertension

This article discusses the pathophysiologic features, diagnosis, treatment, and management of patients with renovascular hypertension. Timely diagnosis is important as the disease can carry a more serious prognosis than essential hypertension and is less amenable to drug treatment. Renovascular hypertension also carries a greater risk of progression to accelerated or malignant hypertension and may result in irreversible ischemic failure of the affected kidney. Various treatments are available including medical management, angioplasty and/or stenting, and revascularization. Regardless of treatment approach, nursing care is an integral part of the patient's management, especially continuing follow-up of blood pressure.

Is prosthetic renal artery reconstruction a durable procedure? An analysis of 489 bypass grafts

OBJECTIVE

Renal artery stenosis has been classically addressed with saphenous vein bypass graft or transaortic endarterectomy performed either primarily or in combination with an aortic procedure. In this series, we report the outcome of our 12-year experience with renal artery reconstruction using prosthetic conduit.

METHODS

Patients undergoing renal artery bypass grafting from 1987 to 1999 were identified. Demographics, indications, concurrent operations, complications, and patency were analyzed. Patients underwent postoperative duplex scan with subsequent ultrasound scans at 6-month intervals.

RESULTS

There were 489 procedures performed in 414 patients with indications: high-grade renal artery stenosis in combination with abdominal aortic aneurysm repair or symptomatic aortoiliac occlusive disease (309 [63%]), renovascular hypertension (118 [24%]), and renal salvage (20 [4%]). Indications for the remainder included trauma, renal artery aneurysm, or an infected aortic graft. Inflow was aorta or aortic graft in 95% of patients with the remainder taken from the iliac or visceral vessels. The retroperitoneal approach was used in 97.8%. Nonfatal complications occurred in 11.4% with a 1.4% early and 4.8% late occlusion rate. Renal function worsened in 3.1% of all patients. Secondary patency at 1 and 5 years was 98% and 96%, respectively.

CONCLUSION

Renal artery reconstruction with prosthetic conduit has an acceptable and durable result whether used for primary renal artery reconstruction or concomitant reconstruction with aortic procedures.

Outcome of renal artery reconstruction: analysis of 687 procedures

OBJECTIVE

To evaluate the short- and long-term results of surgical reconstruction of the renal arteries, the authors review their experience with more than 600 reconstructions performed over a 12-year period.

SUMMARY BACKGROUND DATA

Reconstruction of the renal arteries, whether for primary renal indications or concomitantly with aortic reconstruction, has evolved over the past 40 years. There is concern that renal artery reconstructions carry significant rates of mortality and morbidity and may fare poorly compared with less-invasive procedures.

METHODS

From 1986 to 1998, 687 renal artery reconstructions were performed in 568 patients. Of these, 105 patients had simultaneous bilateral renal artery reconstructions. Fifty-six percent of the patients were male; 11% had diabetes; 35% admitted to smoking at the time of surgery. Mean age was 67 (range, 1 to 92). One hundred fifty-six (23%) were primary procedures and the remainder were adjunctive procedures with aortic reconstructions; 406 were abdominal aortic aneurysms and 125 were aortoiliac occlusive disease. Five hundred procedures were bypasses, 108 were endarterectomies, 72 were reimplantation, and 7 were patch angioplasties. There were 31 surgical deaths (elective and emergent) in the entire group for a mortality rate of 5.5%. Predictors of increased risk of death were patients with aortoiliac occlusive disease and patients undergoing bilateral simultaneous renal artery revascularization. Cause of death was primarily cardiac. Other nonfatal complications included bleeding (nine patients) and wound infection (three patients). There were 9 immediate occlusions (1.3%) and 10 late occlusions (1.5%). Thirty-three patients (4.8%) had temporary worsening of their renal function after surgery.

CONCLUSION

Renal artery revascularization is a safe and durable procedure. It can be performed in selected patients for primary renovascular pathology. It can also be an adjunct to aortic reconstruction with acceptable mortality and morbidity rates.

Renal insufficiency: usefulness of gadodiamide-enhanced renal angiography to supplement CO2-enhanced renal angiography for diagnosis and percutaneous treatment

PURPOSE

To determine whether gadodiamide is a safe and useful angiographic contrast agent for help in diagnosis and percutaneous treatment of renal artery stenosis in patients with renal insufficiency.

MATERIALS AND METHODS

Diagnostic renal angiography and percutaneous renal interventions were performed by using gadodiamide (total dose, 0.3 mmol/kg) and CO2 as intraarterial contrast agents in 25 procedures in 24 patients with renal insufficiency. Serum creatinine levels were obtained within 24 hours before and at 24 and 48 hours after the procedure. Increases in serum creatinine of more than 44 mumol/L were considered clinically important. Gadodiamide-enhanced angiograms were compared with CO2-enhanced angiograms.

RESULTS

In 23 (92%) of 25 procedures, there was no increase in serum creatinine level at 48 hours. One patient with acute and chronic rejection of a renal transplant and one with evidence of cholesterol embolization had a clinically important increase in serum creatinine level at 48 hours. No marked increase in creatinine level was observed in patients with relatively low baseline levels (n = 19). Gadodiamide-enhanced angiograms appeared to be better than CO2-enhanced angiograms for help in identifying renal artery occlusions, visualizing renal vessels incompletely filled with CO2, and determining the progress of intervention.

CONCLUSION

Gadodiamide appears to be a safe and useful intraarterial contrast agent in patients with renal insufficiency and can be used to supplement or confirm CO2-enhanced angiographic findings.

Percutaneous transluminal angioplasty and surgery of the renal artery

The management of patients with renal artery disease has changed in recent years. This has occurred due to the advent of PTA as an effective method of treatment for certain patients, an enhanced appreciation of advanced atherosclerotic renal artery disease as a correctable cause of renal failure, and improved results of surgical revascularisation in both older patients with severe aortic atherosclerosis and younger patients with branch renal artery disease. PTA currently yields excellent results and is the treatment of choice for patients with fibrous dysplasia of the main renal artery and non-ostial atherosclerotic lesions. Most reports in the literature indicate that surgical revascularisation provides more effective therapy for patients with ostial atherosclerotic lesions. Surgical revascularisation also remains the treatment of choice for the majority of patients with branch renal artery disease, a renal artery aneurysm, renal artery occlusion, and recurrent renal artery stenosis after failed PTA or surgery. Excellent clinical results can be achieved with both PTA and surgical revascularisation in properly selected patients.

Laparoscopic ablation of symptomatic renal cysts

We report a laparoscopic approach to the drainage and ablation of symptomatic simple renal cysts. Ten patients with chronic pain, 6 of whom failed primary aspiration, underwent laparoscopic cyst ablation: 6 had solitary renal cysts, 3 had multiple cysts and 1 had a peripelvic cyst. The approach was transabdominal in 9 patients and extraperitoneal in 1. Intraoperatively, cyst fluid was obtained for cytological examination, and cyst walls were excised and sent for pathological examination. When possible, the remaining inner cyst walls were fulgurated to prevent recurrence. Mean total operating room time was 2 hours 27 minutes and blood loss was minimal. The sole complication was a postoperative retroperitoneal hematoma, which was managed conservatively. Malignancy was diagnosed in 2 patients, each of whom had a negative preoperative aspiration. These patients subsequently underwent radical nephrectomy. All remaining patients were asymptomatic at a mean followup of 10 months. Laparoscopic ablation of renal cysts is a safe and effective alternative to open surgery in patients who have failed conservative measures. Preoperative and intraoperative evaluation for malignancy should be performed.

Renal revascularization in high-risk patients: the role of iliac renal bypass

Between 1984 and 1989, 29 iliac renal artery bypasses were performed in 29 patients (mean age 67.8 years) with severe renovascular disease due to atheroma. The indication for renal artery reconstruction was hypertension in all patients, which was associated with kidney failure in 16 cases. In six cases, reconstruction was performed after failure or complications of percutaneous transluminal angioplasty. The bypass was constructed with polytetrafluoroethylene in 24 cases (83%) and vein graft in five cases (17%). There was no postoperative mortality. All bypasses were found to be patent on duplex scanning or digital subtraction arteriograms. One patient was lost to follow-up. Mean follow-up was 23.2 months. One patient died of acute kidney failure, probably related to occlusion of the bypass. Hypertension improved in 22 cases (79%), was cured in two cases (7%), and remained unchanged in four (14%). Renal function remained unchanged in six cases (40%) and improved in nine (60%). Iliac-to-renal artery bypass seems to be the surgical renal revascularization modality best adapted to high-risk patients or those who have severe atheroma. Additionally, this technique enables rapid treatment of failures or complications of percutaneous transluminal angioplasty of the renal artery.