CASE REPORTS

Stabilization of Renal Function, Improvement in Blood Pressure
Control and Pulmonary Edema Symptoms after Opening a Totally
Oc

*Joanna J. Wykrzykowska, MD, §Mark Williams, MD, *Roger J. Laham, MD
*Joanna J. Wykrzykowska, MD, §Mark Williams, MD, *Roger J. Laham, MD
Stenting has emerged as a procedure associated with low mortality and morbidity for symptomatic renovascular disease. Frequently responsible for uncontrollable hypertension, congestive heart failure and progressive renal failure leading to endstage renal disease, it is prevalent among elderly patients.1 Acute pulmonary edema is not an infrequent presentation of severe renovascular disease in the elderly,2 and carries high risk in patients will diminished cardiopulmonary reserve. In most cases, total occlusion of a renal artery supplying a small atrophied kidney has not been considered an appropriate target for intervention. This case demonstrates, however, that atrophied kidneys can be hormonally active, and therefore contribute to significant hypertension and pulmonary edema. We show that, as is the case when restoring patency in a chronically totally occluded coronary artery, recanalization of a chronically occluded renal artery may result in restoration of function.

Case Report. An 81-year-old female with a past history of giant-cell arteritis, hypertension, tobacco use and peripheral vascular disease presented with acute hypoxic respiratory failure due to pulmonary edema that required mechanical ventilation. Echocardiography revealed a left ventricular ejection fraction of 40%, moderate symmetric left ventricular hypertrophy (septal thickness of 17 mm, and lateral wall thickness of 17 mm), mild aortic stenosis with a peak gradient of 27 mmHg, and mild mitral stenosis with a mitral valve gradient of 3 mmHg and mild mitral regurgitation. Cardiac catheterization showed elevated right and left ventricular filling pressures. Coronary angiography revealed mild, nonobstructive coronary artery disease. Angiography of the lower extremities demonstrated total occlusion of the left iliac artery and severe disease in the right iliac artery. Abdominal aortography showed a total occlusion of the left renal artery and moderate (~50%) disease in the right renal artery (Figure 1). Urinalysis by dipstick showed a specific gravity of 1.015, protein 30 mg/dl, 50 red blood cells/highpower field and occasional amorphous casts.

The initial strategy, given the unilateral nature of the patient’s renal disease, was to pursue medical therapy. Her systolic blood pressure remained elevated at 200 mmHg despite treatment with multiple agents (clonidine patch 0.4 mg daily, amlodipine 10 mg daily, doxazosin 2 mg daily, lisinopril 2.5 mg daily and verapamil 480 mg daily), and she continued to have congestive symptomswith Class IV congestive heart failure. Magnetic resonance angiography (MRA) was performed to determine the severity of renal artery disease and the renal size. Again, the left renal artery was found to be severely diseased. The left kidney measured 8.4 cm (Figure 2). The right renal artery had mild disease, and the right kidney measured 10.5 cm. The patient’s creatinine was 2.7 mg/dl on admission, but decreased to 1.6 ml/dl at the time of discharge.
To determine the differential functional status of the left kidney, renal radionuclide scintigraphy with Tc-MAG3 (mercaptoacetyltriglycine) was obtained with dynamic imaging at 2–3 minutes after tracer injection. The left kidney accounted for 18% of renal function, while the right kidney accounted for 82% of function (Figure 3). This study, therefore, confirmed the presence of residual function in the left kidney despite atrophy and total occlusion.

Due to failure of medical management of the patient’s hypertension and congestive heart failure, a multidisciplinary consensus involving the patient and cardiovascular as well as nephrology consultants determined that left renal revascularization should beperformed. The left renal artery lesion was crossed with a Choice PT XS (Boston Scientific Corp., Massachusetts) wire and predilated with 1.5 mm balloon. Subsequent serial dilatations with 2.5, 3.5 and 4.5 mm balloons were done over Stabilizer XS SS (Cordis Corp., Miami Lakes, Florida) wire. An OmniLink 6.0 x 18 mm stent (Guidant Corp., Santa Clara, California) was deployed at 14 atm without complications and showed 0% residual stenosis (Figure 4). After recanalization, we observed filling of a capsular collateral to the left kidney (Figure 5).
Five months postprocedure, the patient’s systolic blood pressure remains better controlled at 160 mmHg and she has not suffered any episodes of congestive heart failure since the procedure. Her creatinine transiently rose to 3.2 mg/dl, likely due to contrast-induced nephropathy postprocedure, but has now stabilized at 1.4 mg/dl. Six months following the index procedure, the patient presented with severe hypertension and congestive heart failure. Renal angiography showed a patent left renal stent and severe stenosis involving the right renal artery, which was stented, thus showing improvement in the patient’s hypertension and congestive symptoms.

Discussion. The prevalence of renal artery stenosis in the elderly approaches 20% after the age of 70 years.3 Approximately 5% of renal artery lesions > 60% diameter stenosis will progress to complete occlusion over a period of 3 years.4 Critical renovascular disease is associated with substantial morbidity and mortality. The survival rate at 2 years is a dismal 56%, with the majority of deaths associated with complications of vascular disease.5 In several studies of patients entering renal dialysis, the prevalence of renal artery disease is 10–20%.6,7 Renal artery stenting has emerged as a safe therapy for both unilateral and bilateral renal artery stenosis and is indicated for refractory hypertension, especially if associated with congestive heart failure.1,8 Numerous studies have demonstrated low restenosis rates and have shown some improvement in the blood pressure control9 as well as improvement or stabilization of creatinine clearance,10,11 while risks have included cholesterol embolization, progression of renal disease and bleeding.
Whether an individual patient will benefit from renal revascularization is often a challenging call, and noninvasive imaging does not reliably predict who will benefit. The positive and negative predictive value of functional renal scans are too low to appropriately guide clinical decisions.3,12 Obtaining informative data is particularly challenging in patients with significant renal impairment and bilateral renal artery disease. MRA and contrast angiography provide anatomic detail of the degree of stenosis, which is presumed to translate into functional impairment and hemodynamic significance, however, these studies are limited by observer bias, particularly with contrast angiography, despite its designation as the “gold standard” for arteriography.13 Doppler ultrasonography has the potential for good accuracy,3,14 but requires a well-trained technician and adequate windows. It has been suggested that a resistive index > 0.8 predicts poor response to revascularization.14,15
This case demonstrates the unique challenges in the treatment of renal artery stenosis, particularly in an elderly patient with an occluded renal artery. We hypothesized that this patient’s hypoxic respiratory arrest was precipitated by progression of the left renal artery stenosis with total acute occlusion of the left renal artery. Stenting of the chronic ostial left renal artery occlusion appears to have stabilized her creatinine at 5 months after the intervention and has allowed for better control of systolic blood pressure (decrease from 200 mmHg to 160 mmHg). Further follow up is necessary to determine whether this effect will be sustained.1,10,11
Recanalization of chronic total occlusions has been shown to be feasible in the coronary circulation16,17 and provides relief of angina and improvement in myocardial function.18,19 A recent study demonstrated that the presence of collateral vessels and more importantly, microvascular function (as measured by coronary flow velocity reserve and fractional flow reserve) after opening a chronically occluded coronary artery correlates with recovery of global myocardial function.18,19 Our ability to demonstrate the presence of collateral vessels through the capsule of the left kidney after recanalization of the total left renal artery occlusion likely indicates that renal parenchyma may have been viable and that some renal function recovery would be possible. Even in the absence of improvement in creatinine clearance, this patient’s clinical improvement may have been mediated through a reduction in activity of the reninangiotensin system after recanalization of the chronic occlusion.
Prior experience from a single surgical study of aortic thromboendarterectomy in revascularization of chronic total renal artery occlusions in 52 patients resulted in improvement in renal function and lowering of blood pressure, but was associated with a 5.7% mortality rate.20 The safety of revascularization will improve substantially with percutaneous techniques, making it more widely applicable, as illustrated in this case.
References
References
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