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Q1: What is the most likely cause of this patient's recurrent pulmonary oedema?
Bilateral renal artery stenosis is a recognised cause of recurrent pulmonary oedema and is the most likely cause of this patient's symptoms. The severity of heart failure does not correlate with the near normal left ventricular function. Hypertension on admission is a clue to the diagnosis.
Q2: What investigations should be performed next?
Diagnostic imaging tests are used to assess the location and severity of the disease; initial screening for bilateral renal artery stenosis is by renal ultrasound, which may show small kidneys. Duplex Doppler sonography can also be used to measure blood flow velocities in the renal arteries. Confirmation of the lesions is by renal angiography (see fig 1), and more recently magnetic resonance angiography. Functional diagnostic tests, for example, renal vein renin sampling, can be used to assess the pathophysiological importance of the stenoses.
Q3: What treatment options are available to this patient?
Definitive treatment is revascularisation of the renal arteries, either by surgery or more commonly percutaneous transluminal renal angioplasty (PTRA) with or without stent insertion (see fig 2). This woman underwent PTRA to the right renal artery and remained symptom free for five years after the procedure.
This case illustrates the importance of recognising bilateral renal artery stenosis as a cause of recurrent pulmonary oedema in the presence of coronary artery disease. It is vital not to assume that the coronary artery disease is the causative factor of the pulmonary oedema. It is not surprising to find atherosclerotic involvement of both renal and coronary arteries in the same subject and previous series have shown this.1 Other authors have also shown recurrent pulmonary oedema to occur with isolated renal arterial disease.2 In our patient echocardiography at initial presentation showed mild impairment of left ventricular contraction which did not correlate with the degree of heart failure and the underlying diagnosis of bilateral renal artery stenosis was correctly identified with PTRA being performed two years later.
Always think of bilateral renal artery stenosis as a cause for recurrent pulmonary oedema.
Hypertension on admission is a clue to the diagnosis.
Atherosclerosis of the renal and coronary circulation occurring in the same patient is relatively common.
Do not prescribe angiotensin converting enzyme inhibitors to treat the pulmonary oedema and hypertension in these patients—this may precipitate renal failure.
Renal vein renin sampling may play a part in predicting the clinical outcome of PTRA.
Definitive treatment is revascularisation of the renal arteries, either by surgery or angioplasty.
Knowing which renal artery would benefit from PTRA in cases of bilateral disease is important. Diagnostic imaging tests, for example, angiography, can be used to assess the location and severity of the disease; in our case bilateral tight stenoses were seen. Functional diagnostic tests can then be used to assess the pathophysiological importance of the lesions and in the case of renal vein renin measurements, this may be used to predict an improvement in clinical state after revascularisation. In hypertension due to unilateral renal artery stenosis, renal vein renin measurements differing by a factor of 1.5:1 or more (higher value from affected side) have a predictive value of improving blood pressure and symptoms by revascularisation in 90% of cases.3 In bilateral disease, the renal vein renin values can often show asymmetry, similar to patients with unilateral disease with the higher value corresponding to the side with the more severe stenosis. The explanation for this asymmetric pattern is presumed to be the same as for unilateral disease and is due to the fact that one side is more severely affected than the other.4 The less ischaemic kidney is exposed to a higher perfusion pressure than the other kidney and this tends to suppress renin secretion. In cases of bilateral disease the more severely affected kidney has the highest renin activity and PTRA to this side has been shown to improve clinical outcome in some patients with hypertension,5 though not in all.5 6 Our patient underwent renal vein sampling from the inferior vena cava which showed a left:right ratio of 1:2.33. PTRA to the right renal artery was performed and this conveyed symptomatic benefit for a number of years after the procedure.
Bilateral renal artery stenosis.
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