Renovascular Hypertension, Surgical Treatment Treatment & Management

• Treat all children with hypertension with antihypertensive medication. In children with severe hypertension, beginning medical treatment before a definitive diagnosis is obtained may be necessary.
• Renovascular hypertension is often refractory to medical treatment. In children with renovascular hypertension, the excellent results of renal artery dilation and surgical revascularization make these procedures the treatments of choice over life-long antihypertensive medication.
• However, attempt to control a patient's blood pressure in preparation for surgical intervention. Especially, defer surgery until manifestations of malignant hypertension are relieved.
• Adrenergic blockers often are an effective means of lowering blood pressure in patients with renovascular hypertension.
• Diuretics may be beneficial.
• Nitroprusside and phenoxybenzamine are useful in the short-term management of malignant hypertension prior to surgery.
• Patients with renovascular disease treated with ACE inhibitors are at risk of decreased renal function. Although this is usually reversible, their use is generally avoided until definitive therapy has been attempted. Certainly, any patients with renovascular hypertension who are treated with ACE inhibitors should have their serum creatinine levels monitored, and therapy should be discontinued if their creatinine levels significantly rise.

The invasive and surgical options for treatment of renovascular hypertension include: (1) percutaneous angioplasty, (2) surgical revascularization, and (3) nephrectomy.

• Percutaneous transluminal angioplasty (PTA): This is a therapeutic radiologic procedure involving expansion of a small balloon on a special vascular catheter to dilate narrow areas in a blood vessel. Balloon expansion to 10 atm of pressure is generally used, and more than one dilation of the balloon may be required to achieve the desired effect.

  • PTA has had mixed results in children. Long-term maintenance of blood pressure improvement ranges from 38-90%. In 1997, Guzetta et al and Tyagi et al found that approximately 25% of patients treated with PTA developed restenosis.^{[4, 2]} In 1995, Casalini et al reported on PTA in a selected group of 36 children with renovascular hypertension.^[5] Of these patients, 34 (94%) were normotensive 2 years after the procedure.
  • PTA is considered cheaper and less invasive than surgical revascularization. It can be performed at the time of angiography. When patients are refractory to treatment or in the event of restenosis, surgery can still be performed. PTA is most effective in mid vessel stenosis. Lesions involving segmental arteries or the ostium of renal arteries and patients with neurofibromatosis were especially refractory to balloon angioplasty. Complications include thrombosis, vascular or renal perforation, and tearing or dissection of the vessel wall. The field of interventional radiology and vascular surgery continues to grow, and improvements in the outcomes of such procedures for management of this problem are likely.
• Surgical revascularization: Reports have shown that more than 90% of patients are cured or have improvement of their hypertension with surgical revascularization. The goal of the surgery is correction of the hypertension with preservation of renal function. Preservation of a functional kidney is especially important because of the high rate of bilateral disease in children.

  • Operative approach: For unilateral renal artery stenosis, a transverse transperitoneal incision may be used. This allows direct approach to the renal artery. Little dissection of the kidney is performed to limit disruption of the collateral vessels. These collaterals provide some renal perfusion during occlusion of the renal artery for bypass of the lesion. Generally, generous operative exposure is required for optimal operative therapy. In 1995, Stanley et al recommended a supraumbilical transverse abdominal incision.^[1] In small children, the incision may need to extend from the xiphoid to the pubis. Reflection of the colon and viscera to the opposite side permit complete control of the inferior vena cava and the renal vasculature. Small children may require evisceration of the intestines for sufficient exposure. Dissecting the renal vein completely free and retracting it upward is usually best.
  • Surgical management of the renal lesion: Dissect the proximal renal artery before approaching the more distal artery to prevent inadvertent injury to small vessels. The aorta is circumferentially dissected just below the renal arteries, and the aortorenal junction is freed when the lesion involves the renal artery ostium. Once everything is free and just prior to cross-clamping, 1 mg/kg of heparin and 0.17 g/kg of mannitol are administered. Broad spatulation of the end of the renal artery or graft creates a generous anastomotic patch for attachment. In small children, perform anastomoses by use of an interrupted monofilament suture to allow for growth. A continuous suture may be used in older patients with a larger anastomosis. When the reconstruction is complete, reversal of the heparin is accomplished with a slow intravenous administration of protamine sulfate 1.2 mg/100 U of previously administered heparin.
• Renal autotransplantation: This involves bypassing the stenotic lesion by reconnecting the renal artery to the aorta in an end-to-side fashion. This procedure has a high success rate but requires extensive mobilization of the kidney. This is the preferred procedure for renal artery stenosis, but use of this method depends on the length of the stenosis and how widespread the renovascular disease is.
• Aortorenal bypass: The most common procedure requires bypassing the lesion by interposition of a graft end-to-side into the aorta and end-to-end to the renal artery. Various techniques can be used, and no uniform agreement regarding the best graft material has been reached.

  • Synthetic graft: Using synthetic graft material or a prosthesis is not the preferred technique. Risk of infection is increased, and technical limitations are associated with the use of this material.
  • Hypogastric artery graft: Stanley et al and Guzetta et al prefer to use a segment of hypogastric artery.^{[1, 6]} Its size conforms to that of the renal artery in most instances; a low incidence of dilation is observed, and it is easily amenable to suturing. Problems with this graft include potential arteritis and the possibility of impotence in patients who had both hypogastric arteries harvested for bilateral reconstruction.
  • Saphenous vein graft: In 1994, O'Neill reported using the saphenous vein as graft material to avoid potential problems with the hypogastric artery graft.^[7] One problem with reversed saphenous vein grafts is the tendency of the graft to dilate. Development of aneurysms occurs in approximately 25% of these grafts, and these tend to occur within the first 2 years postoperatively. To prevent these aneurysms, O'Neill places a 4- to 6-mm Dacron net mandril around the graft. Using the Dacron, Berkowitz et al reported no aneurysmal dilatation in 19 grafts in 1989.^[8] Three of the 19 patients did develop restenosis. Whether this was directly related to the use of a mesh support is unknown. Although this has not been reported, using a synthetic support for the graft has the potential to increase the risk of infection.
  • Aortoaortic bypass: Children with midaortic syndrome or subisthmic coarctation require an aortoaortic bypass using an 8-mm to 12-mm woven Dacron or expanded polytetrafluoroethylene graft. In the classic approach, the bypass is connected to the low thoracic aorta and the bifurcation of the iliacs. Grafts can also extend from the upper abdominal aorta behind the esophagus to the aortic bifurcation. Use the appropriate length of graft material to allow for growth while avoiding kinking. Placing the graft behind the kidney may help to protect the graft. Renal artery bypass grafts may be attached to the aortoaortic bypass graft or to the low aorta. Attachment of the renal artery graft to the native aorta below the coarctation should theoretically result in less anastomotic neointimal hyperplasia.
• Nephrectomy: Use this option as a last resort in the treatment of renovascular hypertension. The goal of treatment in renovascular hypertension is to resolve systemic hypertension without compromising renal function.

  • Because renovascular disease is often bilateral, with the contralateral renal system occasionally not affected until years later, keeping both kidneys functioning when possible is best. However, removal of the kidney is the best form of treatment in severe renal hypoplasia that reduces the functional capacity to less than 10% of the total renal function.
  • Nephrectomy may be necessary if complications arise during revascularization surgery or if the disease is too widespread (especially in segmental arteries) to be effectively bypassed. Children whose hypertension is refractory to the above forms of treatment may also need nephrectomies to correct their high blood pressure. Modern surgical technique has allowed surgeons to perform nephrectomy using laparoscopic surgery (see the images below). Although nephrectomy is rarely indicated in the treatment of renovascular hypertension in children, it can be safely performed using modern pediatric surgical laparoscopy technique. This 3-month-old child with renal dysplasia and refractory hypertension underwent laparoscopic nephrectomy. The photograph illustrates the patient positioning and the placement of small trocars at the time of the nephrectomy. The dysplastic kidney was easily removed through a slightly enlarged umbilical incision. Same patient shown above. The photograph was taken immediately after laparoscopic nephrectomy. This patient was discharged from the hospital 2 days after surgery. This approach eliminates the need for large incisions and facilitates recovery from surgery, minimizing pain and length of hospital stay.

The need for consultation depends on the degree of end-organ damage.

• If a patient has had chronic hypertension that has led to heart failure, consider referring the patient to a pediatric cardiologist.
• Likewise, a patient presenting with neurologic symptoms may need to see a neurologist or neurosurgeon before surgical treatment is started.
• Once a diagnosis of renovascular hypertension is made, prompt treatment of the disease is the best protection against further end-organ damage.

• Placing all patients who are hypertensive on a low-salt diet is recommended. In renovascular hypertension, this is unlikely to correct the systemic hypertension but may assist in managing the hypertension until more definitive therapy can be performed. It certainly does not hurt patients.
• Also, avoid dehydration because this may lead to decreased renal perfusion or increased renin release.