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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3591_Библиотеки_им_академика_М_И_Перельмана.pdf
390
D. Kandasamy and K. Kabilan
mone (TSH) are secreted from pars distalis. Superior and
inferior hypophyseal arteries supply the adenohypophysis
and neurohypophysis, respectively. Inferior petrosal sinus
(IPS) is the major drainage pathway of the pituitary gland
and it connects the cavernous sinus with the internal jugular
vein. Both IPSs drain into the internal jugular veins. Four
common anatomical variants of IPS were described by Shiu
etal. [1–3]. Type 1 is the most common type in which IPS
drains directly into the jugular bulb. In type 2, IPS joins with
the communicating vein that connects the deep cervical
plexus and drains into the jugular bulb. In type 3, multiple
venous plexuses are seen connecting the jugular bulb with
the cavernous sinus with non-identiable IPS.Type 4 is the
rarest type in which IPS drains directly into the deep cervical
plexus with no jugular drainage.
31.2.2 Cushing Syndrome (CS)
CS occurs due to prolonged exposure to increased levels of
cortisol in the blood. Cortisol levels in the blood are maintained by a negative feedback mechanism acting at the
hypothalamic- pituitary-adrenal axis. Corticotropin-releasing
hormone (CRH) secreted from the hypothalamus reaches the
anterior pituitary via a hypothalamic-hypophyseal portal
system which in turn causes the cleavage of proopiomelanocortin (POMC). ACTH, α-melanocyte-stimulating hormone
(MSH), and β-endorphin are the by-products of POMC
breakdown. ACTH further acts on the zona fasciculate of the
adrenal cortex to secrete cortisol. Increased levels of serum
cortisol occur either by the administration of exogenous glucocorticoids or endogenous production by the pituitary gland
or adrenal or other ectopic sites. Based on the production of
ACTH, endogenous CS has been classied into ACTHdependent and ACTH-independent types [4]. In ACTHdependent CS, plasma ACTH levels are usually increased or
normal. However, in ACTH-independent Cushing syndrome,
ACTH is usually suppressed because of the negative feedback mechanism acting at the hypothalamus and anterior
pituitary. A pituitary adenoma is responsible for 80% cause
of endogenous CS [5]. 20% of ACTH-dependent CS occurs
due to ectopic production from non-pituitary tumors [5].
Small-cell-lung cancer and bronchial carcinoids are responsible for the majority of the ectopic cause. The other tumors
that can cause ectopic ACTH production are neuroendocrine
tumors of the gastrointestinal tract, pancreas, and thymus,
medullary carcinoma of the thyroid, and pheochromocytoma. Autonomous secretion of excess cortisol from the
adrenal gland causes ACTH-independent CS which accounts
for 15–20% of endogenous causes [5, 6]. Adrenal adenoma,
adrenocortical carcinoma, ACTH-independent macronodular adrenal hyperplasia (AIMAH), primary pigmented nodu-
lar adrenocortical disease (PPNAD), and McCune-Albright
syndrome are the causes of ACTH-independent CS. In
ACTH-independent CS, unenhanced CT helps in identifying
the cause such as adrenal mass or hyperplasia. But in ACTHdependent CS, CRH test, high-dose dexamethasone suppression test, and MRI of the pituitary region should be considered
as the rst-line investigation. Inferior petrosal sinus sampling should be considered in equivocal cases.
31.2.3 Indication forIPSS Sampling
Bilateral inferior petrosal sinus sampling (BIPSS) is an invasive procedure used in the evaluation of endogenous ACTHdependent Cushing syndrome (CS) to identify the source of
excess production of cortisol—pituitary versus ectopic
source. It has a higher sensitivity (88–100%) and specicity
(67–100%) [1].
31.2.4 Pre-Procedure Instructions
1. Patient to be admitted before the procedure.
2. Part to be prepared for bilateral femoral vein access.
3. Fasting for at least 6hours.
4. Written consent.
5. Laboratory investigations: Renal function test and
PT-INR.
31.2.5 Minimum Hardware Required
1. 5F/6F arterial sheath—2
2. Picard catheter—2
3. Microcatheter—2
4. Angled hydrophilic guidewire
31.2.6 Procedure (Fig.31.1)
Bilateral femoral vein access is achieved using a 5F/6F catheter sheath by the Seldinger technique. Heparin should be
given at a dose of 50U/kg. Simultaneous catheterization of
bilateral internal jugular veins was done by Picard catheter
followed by the introduction of a microcatheter. It is helpful
to use a criss-cross approach—right-side femoral catheter to
left IPS and vice versa. The microcatheter is further manipulated into the bilateral IPS and the position is conrmed. The
ideal position for sampling is the tip of the microcatheter at
the junction of horizontal and vertical segments of IPS [4].
Baseline blood samples should be taken from the bilateral
IPSs as well as from the periphery, once the catheter is prop-
31 Vascular Interventions inEndocrinopathies
391
Fig. 31.1 (a–c). Bilateral
inferior petrosal sinus
sampling. Lateral superselective venogram showing
normal opacication of
bilateral inferior petrosal
sinus (a and b). Venogram of
right inferior petrosal sinus in
anteroposterior view with tip
of the microcatheter placed at
distal right inferior petrosal
sinus showing opacication of
the bilateral inferior petrosal
sinus through intercavernous
reux (c)
a
b
c
erly placed before the administration of CRH.After taking
basal blood samples, an intravenous injection of CRH is
given at a dose of 1 mcg/kg with (a maximum of 100 mcg) in
a peripheral vein. Post-stimulation blood samples are
obtained at 1, 3, 5, 10, and 15minutes [1]. The ratio of ACTH
concentration in IPS to the periphery (IPS/P) should be analyzed. Signicant post-procedure complications are rare.
Rarely, neurological complications such as irreversible brain
stem injury may occur [7].
31.2.7 Result Interpretation
Positive test for central (pituitary) localization is as shown
below:
IPS to periphery (IPS/P) ratio ≥ 2 in a baseline blood
sample (or).
IPS to periphery (IPS/P) ratio≥3in any samples taken
after CRH administration [1, 4, 8–10].
Interspinous ratio≥1.4 helps in lateralization, though not
very specic [8].
31.3 Adrenal Venous Sampling
31.3.1 Adrenal Gland Anatomy
Adrenal glands are retroperitoneal organs located in the
antero-superomedial aspect of both kidneys. The right adrenal gland is triangular or pyramidal in shape and the left
adrenal gland is semilunate. The adrenal gland consists of
the cortex and medulla. Both the adrenal cortex and medulla
have a different embryologic origins and physiological functions. Adrenal cortex is mesodermal in origin and the medulla
392
D. Kandasamy and K. Kabilan
develops from the neural crest cells. Adrenal cortex secretes
three hormones—mineralocorticoid (aldosterone), glucocorticoid (cortisol), and androgen precursors. Glucocorticoid
secretion is maintained by the hypothalamic-pituitaryadrenal (HPA) axis and mineralocorticoids by the reninangiotensin- aldosterone (RAA) system.
31.3.2 Vascular Anatomy
There are three arteries that supply blood to both the adrenal
glands—the superior suprarenal artery from an inferior
phrenic artery, a middle suprarenal artery from the aorta, and
an inferior suprarenal artery from the renal artery. There is a
single central vein on both sides with the short right vein
draining directly into the inferior vena cava and the long left
vein joining with the left inferior phrenic vein before draining
into the left renal vein [11]. The right adrenal vein usually
joins the inferior vena cava (IVC) at the level of T11-L1in the
right posterior quadrant [12]. Some anatomical variations
described on the right side are the central adrenal vein with
multiple accessory veins, the adrenal vein draining into the
right hepatic vein and the accessory hepatic vein joining the
right adrenal vein to form a common trunk before draining
into the IVC [13]. The left adrenal vein ostium is located on
the cephalad surface of the left renal vein in its middle third.
The left adrenal vein also shows some anatomical variation
such as double veins draining into the renal vein and separate
drainage of the left adrenal and inferior phrenic vein [13].
blood samples are collected from the central veins. In super
selective AVS (ssAVS), blood samples are collected from the
tributary veins. There are three tributary veins observed in
each adrenal gland—superior, inferior, and lateral tributary
veins on the right side and lateral, superior-median, and
superior-lateral tributary veins on the left side [16, 17].
ssAVS helps in identifying a segmental lesion in an adrenal
gland which can be managed by partial adrenalectomy. It
also helps in differentiating bilateral focal lesions from BAH.
31.3.5 Pre-Procedure Instructions
1. Written informed consent.
2. Antimineralocorticoid drugs to be stopped 4–6 weeks
before the procedure.
3. Blood pressure control with calcium channel blockers
and alpha-1 blockers.
4. Potassium supplementation to be continued in patients
with hypokalemia.
5. Previous imaging needed for procedure planning and
adrenal vein anatomy.
6. Patient to be admitted before the procedure.
7. Part to be prepared for right femoral vein access.
8. Fasting for at least 6hours.
9. Laboratory investigations: Renal function test and
PT-INR.
10. Administration of cosyntropin 30 minutes prior to the
procedure to dampen temporal uctuations of cortisol at
a rate of 50 μg/h.
31.3.3 Primary Hyperaldosteronism
Primary hyperaldosteronism is responsible for 5–20% of
cases of hypertension [14]. Severe hypertension with other
features such as hypokalemia, adrenal lesion, and the young
onset of symptoms (<40years) raises the possibility of primary hyperaldosteronism. Aldosterone-producing adrenal
adenoma and bilateral adrenal hyperplasia are the common
causes of primary aldosteronism [15]. Adrenal adenomas are
usually seen in younger patients with markedly elevated
aldosterone levels in the blood. The exact differentiation
between the two clinical conditions is required for the appropriate management as surgery is the treatment of choice for
adrenal adenoma and medical management for bilateral
adrenal hyperplasia (BAH). In BAH, smooth, micronodular,
or macronodular enlargement of both adrenal glands is seen.
31.3.4 Indication forAdrenal Venous
Sampling
It is used to identify whether the excess secretion of aldosterone is unilateral or bilateral. In conventional AVS (cAVS),
31.3.6 Minimum Hardware Required
1. 5F/6F arterial sheath
2. 5F Renal double curve (RDC) catheter or cobra catheter
3. Picard catheter
4. Microcatheter
5. Angled hydrophilic guidewire
31.3.7 Procedure (Fig.31.2)
Right femoral vein access is achieved using a 5F/6F catheter
sheath by the Seldinger technique. Heparin should be given
at a dose of 50units/kg. The right adrenal vein is catheterized
using the RDC or cobra catheter. Identication of the right
adrenal vein is difcult during AVS.Reverse curve catheters
such as Simmons 1 or Mikaelson catheter can also be used to
cannulate the right adrenal vein. The left adrenal vein can be
catheterized using RDC or Picard catheter. The RDC or
Picard catheter is advanced into the left renal vein followed
by lateral to medial sweep of the catheter along the cephalad
surface of the renal vein. Adrenal veins and glands are usu-
ab
31 Vascular Interventions inEndocrinopathies
Fig. 31.2 (a and b). Adrenal
venous sampling (AVS).
Venogram of right adrenal
gland showing gland-like
opacication with central
stem and numerous branches
(a). Fluoroscopic image
showing opacication of the
left adrenal vein and
numerous adrenal branches
(b)
393
ally identied by their characteristic appearance on DSA.It
31.4.2 Blood Supply ofthePancreas
appears as a classic gland-like pattern with a central stem
and numerous side branches. Inadvertent cannulation of an
accessory hepatic vein can also mimic this appearance.
Triangular patterns, delta patterns, stellate, and spidery patterns are also described [18]. 4ml blood is to be taken from
bilateral adrenal veins and from the IVC after conrming the
position.
In surgical practice, the pancreas is divided into two parts—
proximal and distal. The head of the pancreas is included in
the proximal part, body, and tail of the pancreas are included
in the distal part. The entire body of the pancreas is supplied
by the dorsal pancreatic artery and the greater pancreatic
artery. Pancreaticoduodenal arcades supply the head and
neck of the pancreas, and splenic artery branches supply the
body and tail of the pancreas. The superior part of the head
31.3.8 Result Interpretation
and neck of the pancreas is supplied by superior pancreaticoduodenal arteries from the gastroduodenal artery and the
Adrenal vein to the IVC cortisol ratio >3 represents successful adrenal vein cannulation [19].
Aldosterone-cortisol (A/C) ratio or lateralization index
(LI)>4 helps in lateralization [19, 20].
inferior part by inferior pancreaticoduodenal arteries from
the superior mesenteric artery. The superior aspect of the tail
and tip of the tail are supplied by caudal pancreatic arteries
and the inferior aspect of the tail is by greater pancreatic and
transverse pancreatic arteries [24]. The venous drainage of
the entire pancreas is by the portal venous system. The
31.4 Pancreatic Venous Sampling
venous drainage of the head and neck of the pancreas is by
the superior mesenteric vein, and the body and tail of the
31.4.1 Pancreatic Venous Anatomy
pancreas are by the splenic vein. The anterior superior pancreaticoduodenal vein drains into the right gastroepiploic
The pancreas is a retroperitoneal organ and is divided into
head, neck, body, and tail. It has both acinar and islet cells
that are responsible for exocrine and endocrine function
respectively. 98% of pancreatic parenchyma is responsible
for the exocrine function and 2% for the endocrine function
[21]. Acini, intercalated ducts, intralobular duct, interlobular
vein or gastrocolic trunk which are the tributaries of the
superior mesenteric vein. The posterior superior pancreaticoduodenal vein drains into the portal vein. The anterior and
posterior inferior pancreaticoduodenal veins which drain the
inferior aspect of the head are the tributaries of the superior
mesenteric vein [25].
duct, main pancreatic duct of Wirsung, and accessory pancreatic duct of Santorini constitute the exocrine part of the
pancreas. The endocrine cells of the pancreas are islet cells
31.4.3 Pancreatic Neuroendocrine Tumors
that are scattered throughout the pancreatic parenchyma.
Various endocrine cells in the islet are alpha, beta, delta,
epsilon, and PP or F cells. Insulin and amylin are secreted by
beta cells, glucagon by alpha cells, somatostatin by delta
cells, ghrelin by epsilon cells, and pancreatic polypeptide by
PP or F cells [22, 23].
Pancreatic neuroendocrine tumors (panNETs) are welldifferentiated tumors and are classied into functional and
non-functional types based on their clinical presentation.
Insulinoma, gastrinoma, and glucagonoma are the common
functional NETs. The majority of them are sporadic. They
394
D. Kandasamy and K. Kabilan
may be associated with familial syndromes such as multiple
endocrine neoplasia 1 (MEN 1), Von-Hippel-Lindau syndrome, tuberous sclerosis, and neurobromatosis type 1in
10% of cases [26]. Insulinomas are the most common functional neuroendocrine tumor of the pancreas and are associated with MEN 1 syndrome in 10% of cases. The 72-hour
fasting blood glucose test is the gold standard for the diagnosis of insulinoma. Gastrinomas are the second most common
NETs of the pancreas and the most common NETs in MEN
1 syndrome [26]. The majority of the gastrinomas are located
in the gastrinoma triangle. It presents as Zollinger-Ellison
syndrome which is characterized by chronic diarrhea, severe
peptic ulcer disease, and gastroesophageal reux disease.
Because of the small size of insulin and gastrin-secreting
NETs, they are very difcult to identify by preoperative
imaging technique such as multidetector CT and endoscopic
ultrasound. Insulinoma can be missed in 10% of patients on
imaging [27]. Selective intra-arterial injection of calcium
gluconate with hepatic venous sampling helps in the correct
preoperative localization of insulinoma. It is superior to CT/
MR/intraoperative exploration in identifying insulinoma in
patients with hyperinsulinemic hypoglycemia [28].
31.4.4 Pre-Procedure Instructions
1. Written informed consent.
2. Part to be prepared for femoral artery and jugular /femo-
ral vein access.
3. Fasting for at least 6hours.
4. Laboratory investigations: Renal function test and
PT-INR.
5. Glucose monitoring required for insulinoma throughout
the perioperative period.
31.4.5 Minimum Hardware Required
1. 5F/6F arterial sheath-2
2. 5F Simmons-1 and Cobra catheter
3. Microcatheter
4. Angled hydrophilic guidewire
31.4.6 Procedure (Fig.31.3)
Right common femoral vein access is achieved using a
5F/6F catheter sheath by the Seldinger technique. Heparin
should be given at a dose of 50units/kg. Reverse curve catheters such as Simmons-1 can be used to cannulate the right
hepatic vein. The position of the catheter should be conrmed by venography. Right jugular vein access can also be
used to reach the hepatic vein. Another arterial access should
be made in the common femoral artery using a 5F/6F catheter sheath by the Seldinger technique. Cobra or reverse
curve catheter is used to cannulate the celiac artery and an
angiogram should be done. Using microcatheter selective
cannulation of distal splenic, proximal splenic, common
hepatic artery, proper hepatic artery, and gastroduodenal
arteries are needed for arterial stimulation. Once the position of the catheter is conrmed after angiography, arterial
stimulation using calcium gluconate can be done. 5ml of
10% calcium gluconate (0.025mEq/kg body weight) diluted
in normal saline should be injected into the arteries for insulinoma and 30units of secretin to be injected for gastrinoma.
Venous sampling is done from the catheter placed in the
right hepatic vein. Blood samples should be taken before
and after stimulation. Post-stimulation blood samples are
obtained at 30, 60, 90, 120, and 180seconds [29]. Additional
blood sampling at 210 seconds is needed in gastrinoma.
Adequate blood samples are obtained following sequential
stimulation of branches of the celiac artery and superior
mesenteric artery.
31.4.7 Result Interpretation
1. Twofold increase in insulin in 30 or 60 s blood samples
[29].
2. 50% increase in gastrin in 30s blood samples [30]
3. Hormone spikes following stimulation of common and
proper hepatic arteries should prompt suspicion of hepatic
metastasis.
31 Vascular Interventions inEndocrinopathies
395
Fig. 31.3 (a–f). Fluoroscopic
image showing MPA catheter
in the right hepatic vein with
opacication of right hepatic
vein (a). Digital subtraction
angiography of splenic artery,
common hepatic artery and
superior mesenteric artery
(b–d). Coronal and axial CT
images showing
neuroendocrine tumor in the
uncinate process of pancreas
(e and f)
a
c
b
d
ef
31.5 Ovarian Venous Sampling
31.5.1 Anatomy
Ovaries are oval- or almond-shaped glands derived from
intermediate mesoderm and are located in the ovarian fossa.
The functional unit of the ovary is the ovarian follicle.
Ovaries secrete estrogen and progesterone in response to the
gonadotropins that are released from the anterior pituitary.
Hypothalamus releases gonadotropin-releasing hormone
(GnRH) into the pituitary portal system which in turn causes
the secretion of luteinizing hormone (LH) and follicle-
stimulating hormone (FSH) from the anterior pituitary. FSH
receptors are seen predominantly in the granulosa cells of the
ovary and LH receptors in theca cells. Theca cells synthesize
androstenedione and testosterone under the inuence of
LH. Androstenedione and testosterone produced from the
theca cells reaches the granulosa cells. An aromatase enzyme
present in the granulosa cells converts androstenedione and
testosterone into estrone and estradiol. Ovaries are the main
source of androgen and estrogen. Paired ovarian arteries that
arise from the abdominal aorta supply bilateral ovaries.
The ovarian vein originates from the plexus in the broad liga-
ment adjacent to the ovary. The right ovarian vein drains into the
396
D. Kandasamy and K. Kabilan
infrarenal IVC with its ostium located in the anterior surface.
Supernumerary veins and ovarian veins draining into the right
renal vein are the anatomical variations described [31].
The left ovarian vein drains into the left renal vein with its
ostium located in the caudal surface. Many anatomical variations are described such as two or three ovarian veins draining into the left renal vein, direct drainage of the ovarian vein
into the IVC, or drainage into the accessory left renal vein.
31.5.2 Hyperandrogenism
Hyperandrogenism is commonly seen in women with a prevalence of 5–10% [31]. Polycystic ovarian syndrome (PCOS)
accounts for the majority of the cases. Hyperandrogenism
presents with the clinical manifestations of acne, hirsutism,
amenorrhea, virilization, and alopecia. Among the mentioned clinical symptoms, virilization warrants meticulous
evaluation for androgen-producing tumors [32, 33]. Ovarian
tumors and adrenal tumors such as adrenal adenoma and
adrenocortical carcinoma can cause hyperandrogenism in
women [34]. Androgen-producing adrenal tumors are usually large and can be easily identied in cross-sectional
imaging. Ovarian sources should be suspected in patients
with normal adrenal glands in imaging. In ovarian tumors,
basal peripheral testosterone levels are usually ≥130ng/dL
[35]. About 1% of ovarian tumors that contain testicular cell
types can cause hyperandrogenism [36]. Sex cord-stromal
tumors account for 7–8% of ovarian tumors and may present
with hyperandrogenism [37, 38]. The primitive sex cord cells
are granulosa and Sertoli cells. Theca cells, broblasts, and
Leydig cells are stromal cells. Androgen-producing ovarian
tumors usually arise from Sertoli and Leydig cells. It is very
difcult to identify small ovarian tumors (<2cm) even on
pelvic ultrasound and can be missed [1]. AVS or ovarian
venous sampling should be considered in the suspected cases
of androgen-producing adrenal or ovarian tumors when
imaging is normal [39, 40].
31.5.3 Pre-Procedure Instructions
1. Patient to be admitted before the procedure.
2. Part to be prepared for right femoral vein access.
3. Fasting for at least 6hours.
4. Written informed consent.
5. Laboratory investigations: Renal function test and
PT-INR.
31.5.4 Minimum Hardware Required
1. 5F/6F sheath introducer set
2. 5F Simmons-1 or cobra-2 catheter
3. Picard catheter.
4. Microcatheter.
5. Angled hydrophilic guidewire.
31.5.5 Procedure (Fig.31.4)
Right femoral vein access is obtained using a 5F/6F catheter sheath by the Seldinger technique. Heparin should be
given at a dose of 50units/kg. Catheterization of the right
ovarian vein can be done by a 5F Cobra-2/Simmons-1
catheter. Systematic sweeping of the catheter in the IVC in
the craniocaudal direction helps in identifying the ostium.
The 5F Cobra-2 catheter is commonly used for catheterizing the left ovarian vein. Microcatheter may be needed for
super- selective catheterization. After placing the catheter
tip at the expected site, digital subtraction venography
should be done to conrm the position followed by the collection of blood samples. Blood samples from both the
ovarian veins and from the periphery are evaluated for testosterone and dehydroepiandrosterone sulfate (DHEAS).
Sometimes, simultaneous adrenal venous sampling is
needed in suspected cases of androgen-secreting adrenal
tumors [39].
31.5.6 Result Interpretation
Ovarian to peripheral testosterone gradient >9.5 represents
the underlying androgen-secreting ovarian tumor [35].
Right–left testosterone efuent ratio>1.44 conrms the
right-sided androgen-secreting ovarian tumor [35].
Left–right testosterone efuent ratio > 15 conrms the
left-sided androgen-secreting ovarian tumor.
cd
31 Vascular Interventions inEndocrinopathies
397
Fig. 31.4 (a–d). Ovarian
venous sampling.
Fluoroscopic AP images
showing opacication of the
right ovarian vein with its
ostium located in the anterior
surface of the infrarenal IVC
(a and b). Fluoroscopic AP
images showing opacication
of left ovarian vein with its
ostium located in the caudal
surface of the left renal vein
(c and d)
a
b
31.6 Renal Artery Stenosis andRenal Vein
Renin Sampling
proximal main renal artery and is associated with poor prognosis [42]. Fibromuscular dysplasia usually affects young
females with a predilection for the middle or distal segments
Renovascular hypertension (RVH) due to renal artery stenosis is one of the important causes of secondary hypertension.
Renal artery stenosis is caused by a heterogeneous group of
conditions affecting single or bilateral renal arteries or their
branches. Atherosclerosis and bromuscular dysplasia are
the common conditions causing renal artery stenosis accounting for approximately 90% and 10% of the cases, respectively [41]. Atherosclerosis affects elderly patients with
narrowing of the renal artery ostium or narrowing of the
of the renal artery. Pediatric hypertension is dened as systolic blood pressure>95th percentile for age, sex, and height
[43]. Pediatric RVH is an important indication for renal vein
renin sampling because it is usually bilateral and segmental.
While atherosclerosis is rare in children, the common causes
of RVH in children are bromuscular dysplasia, neurobromatosis type 1, Takayasu arteritis, and Williams syndrome
[44]. RVH in children is associated with other abnormalities
in the systemic arteries such as mid-aortic syndrome or tho-
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D. Kandasamy and K. Kabilan
racic aorta abnormalities or cerebrovascular disease. Renal
arteriography alone will not be useful in pediatric RVH
because it can affect the segmental renal arteries. In these
situations, renal vein renin sampling helps in identifying the
source of excess renin secretion. In bilateral disease, it is
helpful in deciding which side to attempt revascularization
on rst. In normal individuals, there is a little discrepancy in
renin secretion between the two kidneys. Unilateral pathological secretion of renin of any cause results in increased
blood pressure and suppresses the renin secretion in the contralateral side.
31.6.1 Anatomy
Kidneys are the paired retroperitoneal organs with excretory
as well as endocrine functions. They play an important role
in maintaining intravascular volume, blood pressure, and
electrolyte homeostasis. Blood pressure is regulated by the
renin-angiotensin-aldosterone system. Renin is secreted by
juxtaglomerular (JG) cells in the afferent arteriole of the kidney upon activation. Renin acts on the angiotensinogen produced by the liver and converts it into angiotensin
I.Angiotensin-converting enzyme (ACE) converts angiotensin I into angiotensin II. Angiotensin II acts on the zona
glomerulosa of the adrenal cortex and causes the secretion of
aldosterone [45]. Both angiotensin II and aldosterone cause
sodium and water reabsorption and potassium excretion by
the kidneys, thereby maintaining blood pressure. Both kidneys have a single renal vein which is located anterior to the
renal artery at the hilum. The left renal vein is longer than the
right and has many tributaries such as the adrenal vein,
gonadal vein, and retroperitoneal veins. The common anatomical variations of renal veins are supernumerary veins,
circumaortic, or retro aortic left renal veins. The most common variation is the supernumerary veins or multiple renal
veins [46]. The other anatomical variations are left-sided
IVC and duplicated IVC.Anomalous anatomy is frequently
noted on the left side.
31.6.2 Pre-Procedure Instructions
1. Written informed consent.
2. All antihypertensive medications (especially beta block-
ers and ACE inhibitors) be discontinued for 10–14days.
3. Patient to be admitted before the procedure.
4. Part to be prepared for common femoral vein access.
5. Fasting for at least 6hours.
6. Patient to be relaxed and positioned supine for at least
2hours before the procedure.
7. Laboratory investigations: Renal function test and
PT-INR.
8. Captopril to be administered 60–90minutes before sampling to increase discriminatory capacity by increasing
the difference in renin levels between the two sides.
31.6.3 Minimum Hardware Required
1. 5F/6F sheath introducer set
2. 5F Cobra or RDC catheter
3. Angled hydrophilic guidewire.
31.6.4 Procedure
Right common femoral or internal jugular vein access is
achieved using a 5F/6F catheter sheath by the Seldinger technique. Heparin should be given at a dose of 50units/kg. 5F
Cobra or RDC catheter can be used to cannulate the renal
veins sequentially. The tip of the catheter should be positioned in the right renal vein centrally so that the aspirated
blood reects the efuent from the entire kidney. Blood samples should not get diluted by inow from the gonadal vein or
from IVC variants. One milliliter of blood each is taken from
the infrarenal IVC, bilateral main renal veins, and upper, middle, and lower renal vein tributaries on both sides. Small segmental renal vein sampling can be done with a microcatheter.
Once the blood samples are collected, they should be placed
in heparin plasma and kept either refrigerated or frozen prior
to analysis in order to prevent renin degradation.
31.6.5 Result Interpretation
The ratio of renin from the main renal vein in the affected
side (Ra) and contralateral side (Rc) >1.5 indicates abnormal
renin secretion [47–49].
The ratio of renin in the contralateral side (Rc) and renin
in the IVC blood samples <1.3 indicates contralateral suppression [47–49].
The ratio of renin in the stenotic kidney (S) to peripheral
blood (P) (S/P ratio) >1.5 indicates renovascular hypertension [50].
The ratio of renin in the contralateral kidney (C) to peripheral blood (P) (C/P ratio) <1.25 indicates renovascular hypertension [50].
31 Vascular Interventions inEndocrinopathies
399
31.7 Whole Body Venous Sampling
inTumor-Induced Osteomalacia
Tumor-induced osteomalacia (TIO) or oncogenic osteomalacia is a rare acquired paraneoplastic syndrome characterized
by the overproduction of broblast growth factor 23 (FGF-
23) by the phosphaturic mesenchymal tumors (PMTs). The
excess production of FGF-23 results in hypophosphatemia
and hyperphosphaturia that cause bone pain, fracture, muscle
weakness, and osteomalacia [51]. Tubular reabsorption of
phosphate (TRP) and tubular maximum reabsorption of phosphate to glomerular ltration rate (TmP/GFR) is decreased in
patients with oncogenic osteomalacia. PMTs are grouped
under tumors of uncertain differentiation in the 2020 WHO
classication of soft tissue tumors [52]. It can occur anywhere
in the body and commonly involves bones in 40% of patients
and soft tissues in 55% of patients [53]. They are located frequently in the thigh and femur. Although they are usually
benign, malignant PMTs are also reported in the literature.
They also express somatostatin receptor 2A (SSTR2A), CD
68, and periostin (51). PMTs are usually very small tumors
and are difcult to identify on imaging. Various imaging
modalities such as 111-Indium octreotide scintigraphy, FDGPET/CT, 68-Gallium-DOTATATE PET/CT, and whole-body
MRI help in the localization of PMTs. Functional imaging
should be considered the rst imaging of choice in suspected
PMTs. Similar clinical features can also be seen in a condition called TIO-like syndrome without any underlying PMTs.
The conditions causing TIO-like syndrome are prostate cancer, small-cell carcinoma of the lung, hematological malignancies, neurobromatosis, and polyostotic brous dysplasia
[54]. For a single lesion, functional and anatomical imaging
helps in identifying the tumor- causing hypophosphatemia.
Tumor localization and removal are important as this can
completely reverse all the clinical and biochemical features
[55]. In case of multiple tumors detected on functional imaging or equivocal lesions with a high degree of suspicion then
venous sampling may be needed for conrmation.
31.7.1 Pre-Procedure Instructions
1. Written informed consent.
2. Patient to be admitted before the procedure.
3. Part to be prepared for common femoral vein access.
4. Fasting for at least 6hours.
5. Laboratory investigations: Renal function test and
PT-INR.
31.7.2 Minimum Hardware Required
1. 5F/6F sheath introducer set
2. 5F Picard or multipurpose catheter
3. Angled hydrophilic guidewire.
31.7.3 Procedure
Right common femoral vein access is achieved using a
5F/6F catheter sheath by the Seldinger technique. Heparin
should be given at a dose of 50units/kg. Picard or multipurpose catheters are introduced into the major veins
sequentially and samples are taken. Blood samples should
be representative of the venous drainage of the whole
body. Samples are usually obtained from bilateral internal
jugular veins, subclavian veins, brachiocephalic veins,
superior vena cava, supra and infrarenal inferior vena cava,
bilateral common iliac veins, internal and external iliac
veins, common femoral veins, supercial femoral and popliteal veins.
31.7.4 Result Interpretation
An elevated FGF-23 ratio in the corresponding venous sampling indicates the presence of FGF-23 producing tumor.
Ratio determination is obtained by dividing the highest value
by the mean. A ratio greater than 1.6 is diagnostic [56].
31.8 Conclusion
Venous sampling is functional rather than morphological
localization. It should be considered in patients with high
clinical suspicion of endocrine abnormalities with normal or
equivocal cross-sectional and nuclear imaging. It helps in
identifying the source and lateralization of excess hormone
production, thereby assisting in deciding appropriate clinical
management. Unfortunately, it is limited in use due to technical expertise, lack of literature, radiation exposure, and
anatomical variations of veins. In the future with more literature and expertise, venous sampling will become an indispensable investigation in endocrinopathies.