Treatment of Fibromuscular Dysplasia of the Renal Artery With Cryoplasty

Abstract

Fibromuscular dysplasia (FMD) is a nonatherosclerotic and noninflammatory disease that can result in stenoses of the renal arteries and hypertension. Percutaneous transluminal angioplasty has been considered the gold standard of therapy for FMD. Herein, we present a unique treatment of a patient with FMD using cryoplasty with excellent angiographic result and corroborating images using optical coherence tomography.

VASCULAR DISEASE MANAGEMENT 2013:10(5):E86-E88

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Case Report

A 74-year-old female with a long-standing history of uncontrolled hypertension presented for further evaluation. Her systolic blood pressure was in the range of 160-170 mmHg despite multiple antihypertensive agents, including diuretic, angiotensin converting enzyme inhibitor, calcium channel blocker, and alpha blocker. She had undergone a computed tomography angiography of the abdomen, which showed a “string-of-beads” appearance of the right renal artery and a normal appearing left renal artery. She received a recommendation to undergo a renal angiogram in the setting of uncontrolled hypertension with a preliminary diagnosis of fibromuscular dysplasia (FMD). 

Access was obtained in the right femoral artery and a descending aortogram performed, which revealed no significant aortic disease and patent renal arteries bilaterally.  Selective angiogram of the left renal artery demonstrated no significant disease while that of the right renal artery confirmed midvessel intimal fibroplasia consistent with FMD (Figure 1).

An 8-Fr renal double curved (RDC) guiding catheter (Cordis) was used to selectively engage the right renal artery. Optical coherence tomography (OCT) was performed using a Dragonfly catheter (St. Jude Medical), which confirmed longitudinal intimal irregularities with a reference vessel size of 5.75 mm (Figure 2). A PolarCath 6 x 20 mm balloon (Boston Scientific) was used to perform cryoplasty of the mid-right renal artery (Figure 3).

The patient did not experience any discomfort during the cryoplasty. Repeat OCT imaging confirmed a good result with no further irregularities of the vessel wall (Figure 4). Final angiogram confirmed a good angiographic result with brisk flow (Figure 5). The patient was discharged home the following day with a resting systolic blood pressure of 120-130 mmHg. She returned for follow-up at 1 month post procedure with stable blood pressures.

Discussion

FMD is a noninflammatory, nonatherosclerotic disorder that leads to arterial stenosis, occlusion, aneurysm, and dissection. It has been observed in nearly every arterial bed. The most often involved arteries are the renal and internal carotid arteries, and less often the vertebral, iliac, subclavian, and visceral arteries. Patients with FMD have involvement of the renal arteries nearly 70% of the time and involvement of the extracranial cerebrovascular arteries approximately 65% of the time.¹ Approximately two thirds of patients have multiple arteries involved.^2,3

Among adults, FMD is more common in females, with 85% to 90% of cases being female. It was previously believed that FMD was a disease of young women; however, older individuals account for a large proportion of affected patients in several cohorts, including the United States Registry for Fibromuscular Dysplasia, where the mean age at presentation was 52 years. In another series of 70 patients undergoing treatment for FMD of the cerebral circulation, the mean age at presentation was 62 years.⁴

Treatment options for FMD of the renal arteries include medical therapy alone or revascularization by either percutaneous transluminal angioplasty (PTA) or surgery.⁵ Independent of angioplasty, hypertension should be treated aggressively. PTA has long been considered the mainstay of therapy and offers high rates of improved or cured hypertension. Newer technologies such as cutting balloons have been explored in the armamentarium of treatment choices,⁶ but cryoplasty has not been previously evaluated.

Cryoplasty is an approach introduced with the purpose of reducing vessel injury, elastic recoil, neointimal hyperplasia, constrictive remodeling, and the need for stent implantation. A specially designed PTA balloon applies cold thermal energy while dilating the plaque and the vessel wall. The device used is a microprocessor-controlled coaxial dual balloon and the cooling is achieved by inflating the balloon with nitrous oxide rather than contrast-saline mixture.  The liquid evaporation rapidly cools the outer surface of the balloon from 37°C to -10°C, and the temperature difference is transmitted to the adjacent vessel wall, where it causes freezing of the intracellular fluid. This acute phase change triggers apoptosis of smooth muscle cells,⁷ and the resulting noninflammatory cell death leads to reduced neointimal hyperplasia. Furthermore, freezing-induced alterations in collagen and elastin fibers may temporarily reduce elastic recoil.^8,9 Recently, catheter-based approaches to selective renal sympathetic denervation in patients with resistant hypertension have demonstrated significant sustained reductions in blood pressure.¹⁰ It remains to be studied if cryoplasty has any effect on the renal sympathetic nervous system for further modulation of blood pressure.

Herein, we present the first published use of cryoplasty for treatment of a patient with FMD of the renal artery. The long-term impact of cryoplasty for the treatment of FMD will need to be further evaluated in systematic fashion in larger clinical trials. 

References

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8. Soloff BL, Nagle WA, Moss AJ Jr, Henle KJ, Crawford JT. Apoptosis induced by cold shock in vitro is dependent in cell growth phase. Biochem Biophys Res Commun. 1987;145(2):876-883.
9. Gage AA, Fazekas G, Riley EE Jr, et al. Freezing injury to large blood vessels in dogs. Surgery. 1967;61(5):748-754.
10. Krum H, Schlaich M, Whitbourn R, et al. Catheter-based renal sympathetic denervation for resistant hypertension: a multicentre safety and proof-of-principle cohort study. Lancet. 2009; 373(9671):1275-1281.

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Editor’s Note: Disclosure: The author has completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr. George reports consultancy to Boston Scientific and Cordis. Dr. Desai and Dr. Hsi report no conflicts of interest related to the content of this article.

Manuscript received March 5, 2013; provisional acceptance given April 4, 2013; final version accepted April 16, 2013.

Address for correspondence: Jon C. George, MD, Director of Clinical Research, Division of Cardiovascular Medicine, Deborah Heart and Lung Center, 200 Trenton Road, Browns Mills, NJ, 08015, USA. Email: jcgeorgemd@gmail.com