From the Guidelines
Unexplained acute pulmonary edema should increase suspicion for renal artery stenosis due to its potential to be a manifestation of "flash pulmonary edema," a condition associated with bilateral renal artery stenosis or stenosis in a solitary kidney, as highlighted in the American Heart Association's scientific statement on resistant hypertension 1.
Pathophysiological Connection
The pathophysiological link between renal artery stenosis and fluid regulation is crucial. Renal artery narrowing leads to reduced perfusion, which the kidneys perceive, triggering the activation of the renin-angiotensin-aldosterone system (RAAS). This activation results in sodium and water retention, vasoconstriction, and ultimately volume overload. When combined with the hypertension that often accompanies renal artery stenosis, this volume overload can precipitate sudden pulmonary edema.
Clinical Presentation and Diagnosis
The diagnosis of renal artery stenosis should be particularly considered in patients presenting with recurrent episodes of pulmonary edema despite having normal left ventricular function, those with resistant hypertension, or individuals experiencing worsening renal function after initiating ACE inhibitors or ARBs. The clinical suspicion for renal artery stenosis is heightened in older patients, smokers, and those with known atherosclerotic disease or unexplained renal insufficiency, as these factors increase the likelihood of atherosclerotic renal artery stenosis 1.
Management
Management of patients with suspected renal artery stenosis presenting with acute pulmonary edema involves addressing the acute condition with diuretics. For long-term management, considering revascularization of the stenotic renal arteries through angioplasty with stenting or surgical intervention is crucial in appropriate candidates. However, the decision to proceed with revascularization should be made cautiously, considering the patient's overall clinical context and the potential benefits and risks of the procedure, as randomized clinical trials have not consistently shown a convincing benefit in terms of improvement in renal function or blood pressure control 1.
Diagnostic Challenges
It's also important to note that diagnosing renal artery stenosis can be challenging, with no single non-invasive study offering definitive diagnosis. Duplex ultrasound, magnetic resonance angiography (MRA), renal scintigraphy, and computed tomography (CT) angiography have good test characteristics but vary in true positive and negative predictive value based on the population and institutional expertise 1. Therefore, a high level of clinical suspicion, combined with judicious use of diagnostic tests, is essential for identifying patients who may benefit from further evaluation and potential intervention for renal artery stenosis.
From the FDA Drug Label
In hypertensive patients with unilateral or bilateral renal artery stenosis, increases in blood urea nitrogen and serum creatinine may occur. The presence of unexplained acute pulmonary edema may increase suspicion for renal artery stenosis because it can be a sign of heart failure, which may be related to renal dysfunction. In patients with renal artery stenosis, the use of angiotensin-converting enzyme inhibitors, such as lisinopril, may worsen renal function, leading to oliguria, progressive azotemia, and acute renal failure 2.
- Key points:
- Renal artery stenosis can lead to renal dysfunction
- Angiotensin-converting enzyme inhibitors may worsen renal function in patients with renal artery stenosis
- Unexplained acute pulmonary edema may be a sign of heart failure, which can be related to renal dysfunction
From the Research
Unexplained Acute Pulmonary Edema and Renal Artery Stenosis
- Unexplained acute pulmonary edema can increase suspicion for renal artery stenosis due to the potential link between the two conditions 3, 4, 5, 6.
- Renal artery stenosis can lead to renal insufficiency, hypertension, and subsequently, pulmonary edema 3, 5.
- The activation of the renin-angiotensin system due to renal hypoperfusion from renal artery stenosis can cause volume overload and hypertension, leading to flash pulmonary edema 6.
- Recurrent flash pulmonary edema, also known as Pickering syndrome, is commonly associated with bilateral renal artery stenosis 6.
Diagnostic Considerations
- Duplex ultrasonography is commonly recommended as the best initial test for the detection of renal artery stenosis 4, 6, 7.
- Computed tomography (CT) angiography or magnetic resonance (MR) angiography are useful diagnostic imaging studies for the detection of renal artery stenosis in patients where duplex ultrasonography is difficult 4, 6, 7.
- Renal angiography is useful for a definitive diagnosis of renal artery stenosis if other tests are indeterminate or pose a risk of significant renal impairment 6.
Clinical Implications
- A high index of clinical suspicion for renal artery stenosis is necessary in the setting of recurrent flash pulmonary edema and severe hypertension in patients with atherosclerotic disease 6.
- The restoration of renal artery patency by revascularization in the setting of renal artery stenosis due to atherosclerosis may help in the management of hypertension and minimize renal dysfunction 3, 6.