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Role of Endovascular Recanalization and Stenting of Total Occlusions of the Renal Arteries for Blood Pressure Control in Resistant Hypertension
Iskren Garvanski*, Ivo Petrov, Iveta Tasheva, Iana Simova, Mihail Marzyanov and Gloria Adam
University Hospital Cardiology department, Bulgaria
Submission: December 27, 2016; Published: January 17, 2017
*Corresponding author: Iskren Garvanski, City Clinic University Hospital Cardiology department, Bulgaria, Sofia, str. Okolovrasten pat 127, Tel: +359885933752;Email:firstname.lastname@example.org
How to cite this article: Iskren G, Ivo P, Iveta T, Iana S, Mihail M. Role of Endovascular Recanalization and Stenting of Total Occlusions of the Renal Arteries for Blood Pressure Control in Resistant Hypertension. J Cardiol & Cardiovasc Ther 2017; 3(1): 555601. DOI: 10.19080/JOCCT.2017.03.555601
The purpose of our research was to assess the effect on blood pressure (BP) control and rennin levels of the Percutaneous recanalization of totally occluded renal arteries in patients with resistant arterial hypertension, preserved blood flow in the sub-segmental renal arteries, and high level of plasma rennin. we examined 7 patients with total occlusion of a renal artery and collected data for partially preserved sub segmental circulation.
Percutaneous recanalization was attempted in all of them. Success was achieved in 6 (85.7%) of the cases.All patients were hypertensive before the procedure, with mean BP values of 167.1/95.1 mmHg under systematic antihypertensive treatment with at least 3 antihypertensive agents. In all patients, plasma rennin activity levels were more than 2,5 ng/mL/h before the procedure. The patients had duplex signs of occluded renal artery and partially preserved sub segmental flow. For recanalization of the occlusions of the renal arteries, we used coronary CTO techniques. Clinical and Duplex follow-up was performed at 4 weeks, 3 months, 6 months, and 1 year after the intervention. BP was significantly reduced in all of the patients who had undergone successful revascularization. Two cases of in stent restenosis showed increased BP levels, which normalized again after the second PTA. In all of the patients with successful procedure, normal rennin levels were established at 6 months and 1 year.
Keywords: Total renal occlusion; Resistant hypertension; Endovascular treatment; Plasma renin activity; Sub segmental flow; Revascularization of total occlusion
Hypertension affects more than 25% of the world wide adult population . Although the vast majority of patients suffer from essential hypertension, it is important to identify patients with secondary treatable causes of hypertension, especially renal artery stenosis (RAS), which is the usual cause of hypertension resistant to medical treatment . The two main causes of renal artery stenosis are atherosclerosis and fibromuscular dysplasia (FMB). Atherosclerosis accounts for about 90% of all cases of RAS, while FMB is the cause of about 10%. FMD is most common in women between 20 and 50 years of age and its progression to total occlusion is rare, compared to that of atherosclerotic renal artery stenosis .
Atherosclerotic disease of the renal artery, which is frequently responsible for uncontrollable hypertension, congestive heart failure, and progressive renal failure leading to end stage renal disease, is prevalent among elderly patients . The first percutaneous transluminal renal angioplasty (PTRA) for the treatment of atherosclerotic renal artery stenosis was performed by Gruentzig in 1977; the same year asthe first coronary angioplasty was performed [5,6]. Later on, stenting has emerged as a procedure, associated with low mortality and morbidity for symptomatic renovascular disease. Since then, a lot of clinical data has been gathered, raising controversies about the effect of renal artery stenting in the treatment of renovascular hypertension and chronic renal failure. Further, while stenting of the renal artery stenosis is still justified and widely performed, chronic total occlusions (CTO) of the renal arteries are largely considered inappropriate for endovascular treatment [7,8].
Indeed, in most cases, the total occlusion of a renal artery,
supplying a small atrophied kidney may not be considered an
appropriate target for intervention. In fact in the largely accepted
guidelines, the small size of the target kidney (less than 7 cm) is
a contraindication for renal artery intervention. However, in case
a group of patients with occluded renal arteries, which have the
potential to benefit from recanalization and full restoration of
flow after balloon PTA or stenting, it is important for them to be
identified. There are scarce clinical data for technical feasibility
and clinical effect of the percutaneous recanalization of occluded
renal arteries and only several case reports with positive results
have been published thus far [9-11].
The purpose of this registry was to test whether Percutaneous
recanalization and stenting of totally occluded renal arteriesmight be justified as effective in reducing the blood pressure
(BP) in some patients with chronically occluded renal arteries
and to identify specific predictors of clinical effect, which are
probably preserved cortical blood flow and high levels of plasma
Inclusion criteria for this pilot registry were as follows:
Resistant arterial hypertension
Duplex evidence of total renal artery occlusion
High level of plasma renin activity > 2.5 ng/mL/h.
Doppler sonographic evidence of preserved flow in
the sub segmental arteries (interlobular and arcuate arteries)
(Tables 1 & 2).
*IR – index of resistance of the interlobular arteries
**PRA – plasma renin activity
In the registry, all consecutive patients between January 2011
and May 2015 who fulfilled the inclusion criteria were included.
Seven consecutive patients (3 women, 4 men) at average age of
42.8 years (range, 15-67 years) met the inclusion criteria and
were included in the registry. Percutaneous recanalization of
the renal artery occlusion was attempted in all 7 patients. The
underlying pathological vascular process was as follows: three
of the patients had fibromuscular dysplasia, one had Takayasu
arteritis, one had dissection, and two of the patients had
atherosclerotic renal artery occlusions. All 7 patients had severe
uncontrolled arterial hypertension, defined as average systolic
pressure of >140 mmHg and average diastolic pressure of >90
mmHg, while on treatment with ≥3 antihypertensive drugs, at
least one of which was a diuretic. Average BP values obtained
by 24-h ambulatory BP monitoring (ABPM) including on the day
before hospital admission were a mean of 167.1/95.1 mmHg.
Technical success was defined as restoration of the ante
grade contrast delivery in the sub segmental renal arteries, lack
of residual stenosis > 50% and /or flow limiting dissection. All
patients had Duplex signs of renal artery occlusion: 2 of the
left renal arteries and 5 of the right renal arteries, as well as
partially preserved sub segmental flow, appeared on color coded
Duplex sonography. Three of the patients showed normal serum
creatinine levels, three showed CKD not indicated for dialysis
treatment, and one was undergoing chroniodialysis.
For treating chronic totally occluded renal arteries, coronary
CTO techniques were used. In three cases, the procedure was
performed using a 6 Fr right radial approach with a JR 3.5/6
Fr guiding catheter; three with right femoral approach and one
with right brachial approach. The unsuccessful procedure was
done through femoral approach.In all of the 6 successful cases
crossing of the lesion were achieved using CTO dedicated guide
wires and the use of a low profile over-the-wire OTW balloon.
Coronary balloons were used for predilatation (ranged
approximately 1.25-2.0 mm in size) and post dilatation ranged
5.5-7.0 mm). In the cases with successful recanalization three
dedicated renal stents were implanted and three drug eluting
coronary stents in the other cases. Stents were positioned to
protrude 1-2 mm into the aortic lumen with an average inflation
pressure of 12 atm for the implantation itself and reaching up to
20 atm for ostial trumpeting (or flaring).
Immediately after the stent deployment, a loading dose of
clopidogrel 450 mg, followed by maintenance dose of 75 mg/
day was administered for at least 12 months, and aspirin at a
dose of 100 mg/day was administered to all stented patients.
In all of the patients a Doppler assessment of the stent patency
was performed the day after the procedure. Then, a follow-up
ultrasound was scheduled at 30 days, and at 3 and 6 months
after the procedure. Additionally, control 24-h ABPM and plasma
renin activity were scheduled 30 days after the procedure to
evaluate BP control and the relationship with the renin levels.
Percutaneous recanalization of the chronic renal artery
occlusion was attempted in seven patients. The treatment showed
technical success in six cases and was completed with good
immediate angiographic result with no residual stenosis and
transstenotic gradient and restored peripheral sub segmental
blood flow. All seven patients were thoroughly monitored for
adverse clinical events (vascular access complications, plasma
creatinine levels increase, myocardial infarction, unexpected
drop or increase of the systemic BP, bleeding complications,
stroke or other neurological events). No adverse clinical events
were registered during the hospital stay and 30 days after the
The 24-h ABPM in the successfully recanalized renal CTO
patients, performed 30 days after the renal stenting showed a
dramatic decrease in the BP values, with an average of 132.5/81.7
mmHg compared to 167.1/95.1 mmHg before the procedure.
In the patient with unsuccessful recanalization, no significant
change of BP control or medication was registered. In the
successful recanalization group the medication intake dropped
from average 5.11 agents per patient before the procedure to an
average of 1.17 per patient. Two patients needed no medication
for the arterial hypertension, two patients were using only
one medication, one was on double therapy, and one on triple
therapy. In all of the cases, adequate BP control was achieved
with ABPM not exceeding values of 140/90 mmHg.
During the 6-month follow-up, two of the patients had instent
restenosis with reoccurrence of the unsatisfactory BP
control with registered re-elevation of the PRA. In the first case
(the female patient with Takayasu arteriitis), this occurred 4
months after the procedure, and in the second case it occurred
after 3 months. Both patients underwent successful second PTA:
in the first patient, a second stent was implanted and treatment
with oral rapamune 2 mg/day was administered for 1 month
to prevent reoccurrence of restenosis. The second patient was
treated with efficient balloon PTA with a noncompliant balloon
and additional drug eluting balloon inflation.
Further, the patients were followed up by Doppler ultrasound
of the renal arteries and a clinical exam for an average of 18
months (6-26 months). All of the patients had normal BP values,
<130/85 mmHg at the 12-month visit and no evidence of
restenosis (secondary patency rate=100%). They followed their
existing treatment regimen: two patients with no therapy and
other two with monotherapy.
The prevalence of renal artery stenosis in the elderly
hypertensive patients approaches 20% after the age of 70 years
. Approximately 5% of renal artery lesions with >60%
diameter stenosis will progress to complete occlusion over a
period of 3 years . 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 . In several studies
in patients undergoing renal dialysis, the prevalence of renal
artery disease is 10-20% . Acute pulmonary edema is not
an infrequent presentation of severe renovascular disease in
the elderly  and carries high risk in patients with decreased
cardiopulmonary reserve and is one of the current indications
in the present guidelines. The DRASTIC, ЕММА and ASPIRE-2
studies showed that renalstenting resulted in improvement of
BP and reduced the number of antihypertensive medications
The ASTRAL and CORAL studies showed that there is no
significant difference between the group with renal stenting and
the group medical therapy [18,19]. Doppler ultrasonography
may potentially have good accuracy in assessing renal artery
stenosis/occlusion and preserved subsegmental collateral blood
flow (Figures 1 & 2), and it may be a useful tool for assessing
which patient will respond to endovascular revascularization in
renal stenosis, but requires a well-trained operator and adequate
ultrasound windows. It has been suggested that a resistive
index > 0.8 predicts poor response to revascularization .
Several small trials have tried to establish surgical treatment
as a standard procedure to treat resistant hypertension in case
of total renal occlusion. Whitehouse published the results of
30 patients with renal CTO surgically treated. The registered
mortality was 6.6% and the nephrectomy incidence was 36.6%
Endovascular revascularization of occluded renal artery
is still considered controversial, but has the potential of lower
morbidity/mortality [7,8]. Total occlusion of renal arteries
is not considered as a standard indication for endovascular
intervention. There are no trials or big series published to date.
We found several case descriptions with favorable results from
the procedural and clinical point of view.
Murat Sezer et al.  reported two cases of revascularization
of occluded renal artery in patients with severe hypertension
and high level of creatinin. After the procedure, they established
significant improvement over the control of BP with a significant
reduction of used anti hypertensive drugs .
Wykrzy kowska et al.  reported a case of an 81-yearold
woman with a 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 and chronically occluded the
left renal artery. After recanalizatoin of chronically occluded
artery reported improvement in the patient’s hypertension and
congestive symptoms .
Yokoy et al.  reported a case of left renal subtotal stenosis
and right renal artery total stenosis and concomitant CAD with
favorable clinical result after bilateral renal artery intervention
(better BP control and improved renal function) . They
suggested that preserved blood flow and kidney structure may
be one of the factors indicating renal artery CTO recanalization.
Our personal opinion is that preserved collateral flow to the
kidney can lead to functional survival of the juxtaglomerular
apparatus; thereby leading to high renin production and resistant
hypertension totally independent from kidney’s functioned and
size. On the other hand, the preserved collateral flow is, at the
same time, a predictor of efficient BP control after successful
recanalization. In our cases, high level of rennin production
together with preserved subsegmental collateral flow was an
indication for intervention and a predictor for clinical success,
and both are considered as possible predictors for significant
reduction of BP values after successful recanalization. This has
to be proven in larger trials.
Vascular access and French size of the materials used for renal
artery interventions is another interesting point of discussion.
According to our extensive experience with renal artery
interventions (including not only PTA and stenting but also renal
denervation in more than 200 patients during the last 5 years)
upper access (radial or brachial) is more convenient for renal
interventions because in hypertensive subjects, the renal artery
arises at a sharp angle from the aorta in the caudal direction
causing complications for the manipulation of catheters and
devices from the “classic” femoral access in many cases. In these
cases, is much easier and faster to engage a guiding catheter (in
our protocol the JR 4.0/ 6 Fr is the preferred one) into the ostium
of the renal artery or at least to be axial versus the axis of the
renal artery (because in part of the cases the occlusion is almost strictly ostial and real engagement is not possible).
In these cases, crossing across the minimal proximal stump
is much more probable because of the better push ability of
devices such as microcatheters and wires and better axial
alignment between the axis of the guiding catheter and the axis
of the occluded renal artery. It also provides better support for
driving and implanting a stent. Other reason to use a preferably
radial approach is the fact that it is related to significantly lower
incidence of bleeding complications and lower overall MACE
that is categorically shown in several “coronary” trials (such as
RIVAL and RIFLE) .
Regarding the French size: nowadays major part of
contemporary interventional devices including stent systems
dedicated to visceral and renal arteries are compatible with 6
Fr guiding catheters. In many cases, the size of the kidney and
the artery in case of CTO are smaller than the usual, advocating
the use of coronary DES in order to prevent restenosis and
enabling the use of 6 FR, thus allowing really minimally invasive
approach (radial/ulnar) and reducing vascular complications
and morbidity and mortality.
Size of the treated kidney in our series the average size of
the treated kidney (6.3cm) is much smaller compared to the
indicated size approved in the guidelines for intervention. The
reason we did not consider the contraindication for intervention
in such “small” kidneys is because we were studying the decrease
in rennin level and not improvement of kidney function. In
some of our patients, the excretion function of such kidneys
was categorically shown (by nuclear investigation) to be totally
lost and was less probable to be restored after recanalization.
However, as shown in our group of patients, the kidney size
doеs not affect the potential for high rennin production and the
potential for beneficial effect on the BP control after successful
recanalization and normal systemic flow restoration reaching
the receptors in the juxtaglomerular apparatus (negative
In case of renal occlusion and resistant AH, preserved
renin production as a consequence of preserved collateral subsegmental
blood flow is a predictor of clinical success after
recanalization. The most probable mechanism of AH is the
preserved vascular microcirculation allowing juxtaglomerular
survival and elevated renin production. At the same time,
preserved micro circular perfusion is a predictor of lowering renin
levels and success of BP control after renal CTO recanalization.
There is evidence of a direct relationship between preserved
parenchymal flow and expected post interventional result in
terms of BP control, confirmed in our cases.
The recanalization of total renal artery occlusions is feasible
and safe and has a positive effect on lowering the plasma renin
activity and BP control. This procedure has to be applied only
to a selective group of patients with resistant hypertension and evidence of preserved sub segmental flow. Further, larger
multicentre trials need to be performed to establish the exact
indications and results before broader application of this
strategy to the daily clinical practice.