Distal radial artery in endovascular interventions

Abstract

Forearm and hand arteries are preferrable for use as an access site when performing endovascular interventions. The common place for radial artery catheterization is forearm at its distal third, but another site to puncture the radial artery is located within the anatomical snuffbox, and distally, at the dorsal hand surface, in the vertex of the angle between the long extensor of the thumb and the second metacarpal bone. Radial artery catheterization within the anatomical snuffbox followed by hemostasis allows to preserve distal blood flow in the superficial palmar arch thus reducing the risk of occlusion of the access artery. Moreover, this approach also reduces the risk of redundant compression with following occlusion of the access artery.

Full text

Distal radial artery in endovascular interventions
AL Kaledin1, IN Kochanov1, PS Podmetin1, SS Seletsky1, VN Ardeev1
1 Mechnikov's Northwestern State Medical University, 191015, 47, Piskarevsky ave., St.
Petersburg, Russian Federation
2 "Vsevolozhskaya KMB" state budgetary interdistrict hospital, 188643, 20, Koltushi
highway, Vsevolozhsk, Russian Federation
Kaledin Alexander Leonidovich, candidate of medical sciences, surgeon, tel. +79213049946,
e-mail: alkaledin@mail.ru;
Kochanov Igor Nikolayevich, candidate of medical sciences, Head of Department;
Ardeev Vladimir Nikolayevich, Head of Department;
Podmetin Pyotr Sergeevich, cardiac interventionalist;
Seletsky Sergey Sergeevich, cardiovascular surgeon.
Summary. Forearm and hand arteries are preferrable for use as an access site when
performing endovascular interventions. The common place for radial artery catheterization is
forearm at its distal third, but another site to puncture the radial artery is located within the
anatomical snuffbox, and distally, at the dorsal hand surface, in the vertex of the angle
between the long extensor of the thumb and the second metacarpal bone. Radial artery
catheterization within the anatomical snuffbox followed by hemostasis allows to preserve
distal blood flow in the superficial palmar arch thus reducing the risk of occlusion of the
access artery. Moreover, this approach also reduces the risk of redundant compression with
following occlusion of the access artery.

Keywords: forearm radial artery; radial artery within anatomical snuffbox; radial artery at the
dorsum of hand; radial artery occlusion.
Background
Radial arterial access for performing interventional procedures was first introduced in
1989[1] and in 1993 [2]. Radial artery catheterization is a fundamental approach that is used
as a procedural access in the different catheterization laboratories in more than 90% of
procedures [3] due to low prevalence of access-related complications. Feasibility and safety of
this technique initially provoked some euphoria among interventional specialists, but later
there was a realization of disadvantages of the technique and an evaluation of possible
complications of radial artery catheterization including arterial spasm, tortuosity, vessel
thrombosis (occlusion) and different types of wall lesions of the access artery. For the
evaluation of complications it's useful to consider the anatomy of forearm and hand vessels.
Arteries of forearm and hand are presented by radial and ulnar arteries that run toward the
hand where they form superficial and deep palmar arches (Fig. 1). Traditionally, the optimal
radial artery puncture site was considered to be at the distal third of forearm because of the
superficial position of the artery closely to the radial bone that facilitates puncture and
following hemostasis. Another site for the puncture is anatomical snuffbox where the artery
lies closely to the skin along the surface of radiocarpal joint that serves as "basement" [4]. The
distinctive feature of this area is its location distally to the superficial palmar branch of radial
artery that communicates with superficial palmar arterial arch. And finally, the third possible
puncture site of radial artery is located even more distally - at the dorsum of hand, in the
vertex of the angle between the long extensor of the thumb and the second metacarpal bone
(Fig. 2). In this area, the radial artery is surrounded by soft tissues of hand, which is essential
for the adequate hemostasis.

Figure. 1 Blood vessels of distal forearm and hand
Figure 2 Catheterization site of radial artery at forearm and at hand (marked with black
arrows, left to the right: radial artery of the dorsum of the hand - RADH; radial artery within
the anatomical snuffbox - RAAS; forearm radial artery - FRA).
Performing the endovascular interventions via forearm radial artery (FRA) is considered
preferable due to the lower risk of access site bleeding [5]; this is caused by above-mentioned
anatomical proximity of the radial artery to the "bone basement".
1- ulnar artery
2, 3 - deep palmar branch of radial artery
4, 9 - superficial palmar arch
5 - digital arteries
8 - artery of the thumb
10 - radial artery

Arterial wall damages in access site are multi-faceted: perforation and/or pulsatile
haematoma (false aneurysm), injury of proximal major blood vessels, arteriovenous fistula.
Post-catheterization radial artery occlusion (PCRAO) is the most common complication of
radial access; it's reported by different authors to occur in 0-10% of cases [6]. There are three
fundamental causes of the access artery occlusion: arterial puncture; arterial catheterization
[7] and incorrect puncture hemostasis [8]. Long-term complete radial artery compression that
can lead to PCRAO [8] is a result of nothing else than a mistake of an operator who applies
hemostatic bandage. Relatively high rates of this complication prompted us to search for ways
to minimize the problem. We modelled several cases of occlusions of forearm and hand
arteries (Fig. 3-5).
Fig. 3. Case modelling of FRA occlusion with retained blood flow in ulnar artery and filling of palmar arches.

Fig. 4. Case modelling of ulnar artery occlusion with active blood flow in radial artery and filling of corresponding
blood supply area and palmar arches.
Fig. 5 Case modelling of radial artery occlusion within the anatomical snuffbox with active blood flow in radial and
ulnar arteries and filling of palmar arches.
On the basis of observations, we made the suggestion that in case of total radial artery
occlusion within the anatomical snuffbox (RAAS), the antegrade blood flow would be
preserved through the superficial palmar arch, therefore the risk of thrombosis and extensive
forearm radial artery occlusion would be minimized. Radial artery portion of the hand is
surrounded by soft tissues that are elastic by nature; this leads to "noncomplete" artery
compression with a hemostatic bandage applied to this area. Combining this consideration
with the aforementioned possibility of preserved antegrade blood flow in the superficial
palmar arch makes to suggest lower risk of post-catheterization radial artery occlusion in this
area.
We believe that post-puncture and post-catheterization occlusions are caused by
individual arterial wall reactions on mechanical effect of endovascular manipulations within
the artery. The findings of the histological studies after the radial artery puncture and
catheterization showed significant pathologic changes affecting all arterial layers: medial
inflammation, tissue necrosis, endothelial dysfunction, impairment of smooth muscle cell
layer, intimal hyperplasia, cell proliferation, collagen synthesis, adventitial

neovascularization, internal remodelling, thrombosis [7]. Probably, these data suggest one of
explanations of stenoses that develop in radial arterial grafts after CABG in some patients.
The post-catheterization impairment of the radial artery does not manifest only with
occlusion but also with stenosis. The pulsation over a length of the radial artery is preserved
but its use as an access artery seems problematic (Fig. 6).
Fig. 6 Post-catheterization stenosis of the proximal portion of radial artery (author's observation).
Therefore, prior to repeat catheterization procedures it may be necessary to perform the
ultrasound examination of planned forearm and hand arteries of access.
In our hospital we performed analysis of radial artery changes before and after
catheterization at different time periods using optical coherence tomography. To comprehend
these changes in the arterial wall we primarily evaluated OCT-imaging results of radial artery
prior to percutaneous coronary intervention - PCI (Fig. 7).

Fig. 7 OCT-picture of distal FRA prior to PCI (primary intervention). The RAAS is catheterized (our observation).
One of early signs that is believed to be a trigger factor of radial artery stenosis or
occlusion is an intimal dissection far from the puncture/catheterization site (Fig. 8).
Fig. 8 OCT-picture of distal FRA after PCI. The area of intimal dissection is visible. RAAS is catheterized, primary
procedure (our observation).
After the endovascular intervention, radial artery media and adventitia are involved in
the pathological process more lately (Fig 9, 10).

Fig. 9 OCT-picture of distal forearm radial artery with medial calcification and intimal
injury. RAAS is catheterized. 2 years after PCI (our observation).
Fig. 10 Post-puncture distal FRA stenosis 3 months after the catheterization. Medial hypertrophy,
adventitial neovascularization (our observation).
To minimize the above-mentioned pathological changes in the wall of the radial artery it
may be justified to use a mixture of heparin, nitroglycerine and verapamil solutions with
normal saline. It is also appropriate to use hydrophlic-coated sheaths [9].
To prevent radial artery from occlusion for future access we proposed to catheterize it
distally to its superficial branch communicating with the superficial palmar arch:
1. within the anatomical snuffbox (Fig. 11);

Fig. 11 Radial artery catheterization within the anatomical snuffbox (our observation).
at the dorsum of hand - in the vertex of the angle between the long extensor of the thumb
and the second metacarpal bone (Fig. 12).
Fig. 12 Radial artery catheterization at the dorsum of hand (our observation).
The purpose of our study was to develop and to implement a novel radial artery access
(located at hand) for performing endovascular interventions. Also, we pursued our object to
reduce the rate of access-related complications.
Materials and methods
From 2013 through 2016 a total of 5983 patients underwent radial artery catheterization.
Access arteries included:
1. forearm radial artery (FRA) - 3099 patients (51,8%);
2. radial artery within the anatomical snuffbox (RAAS) - 2775 patients (46,4%);
3. radial artery at the dorsum of hand (RADH) - 109 patients (1,8%).

The catheterization technique was similar among the groups, with a slightly different
needle-skin angle in case of RADH puncture (70-75˚). The catheterization algorithm of
forearm and hand portions of radial artery included: palpating for the radial and ulnar arteries
to detect the pulsation; blood pressure measurement on both hands; US examination of
forearm arteries bilaterally with the measurement of arterial diameters; Allen's test was
initially used, but since then it has been abandoned because of low significance of the results.
The follow-up was performed in patients with multistage endovascular interventions at the
repeat procedures. The number and success of repeat catheterizations were reported. The
French size of the tools used was 5 - 8 (Table 1).
Table 1. The size of the instruments used in PCI procedures.
Instrument size
FRA
(n = 3099)
RAAS
(n = 2775)
RADH
(n = 109)
5 Fr
0,7%
0,4%
-
6 Fr
98,8%
98,4%
99,1%
7 Fr
0,5%
1,1%
0,9%
8 Fr
-
0,1%
-
While implementing in our clinic the arterial access within the anatomical snuffbox and
hereafter - at the dorsum of the hand on a routine basis, we analysed the time to artery
catheterization (learning curve), the fluoro time and the absorbed dose of radiation (when
performing coronary angiography procedures). Statistical analysis of the results included
median values (Me) and interquartile ranges (Q25–Q75) of the above parameters. Student's t-
test was used for the multiple comparisons of the values.
Results and discussion.

FRA has maximal diameter by US of forearm and hand arteries. Ulnar artery and RAAS
didn't differ significantly in diameter (Fig. 13).
Fig. 13 Diameter of forearm and hand arteries prior to endovascular interventions. Note
- * median values presented.
The "time to catheterization" analysis showed comparable rates between forearm and
hand radial artery access sites (Fig 14) after performing approximately 50 procedures.
Fig. 14 Time* to catheterization as a function of number of manipulations performed.
Note - * median values presented.
Considering work specifics of our clinic, radial access at the forearm and at the hand
was used for endovascular coronary interventions in most of cases (Table 2).
Table 2. Forearm and hand radial arterial access for performing endovascular
interventions.
2,7
2,5 2,4
FRA Ulnar atrery RAAS
diameter of artery * (mm)
145
85 80 83
47 42 50 45 48 50 52 49 51
170
125
90 85
55
40 40
56 52 54 50 51
44
53
47 51
254 237
116
57 52
62 60 56
0
50
100
150
200
250
10 20 30 40 50 60 70 80 90 100 150 200 300 400 500 550
time to FRA catheterization, s
time to RAAS catheterization,
s
time to RADH catheterization,
s

Area
Interventions
FRA
(n = 3099)
RAAS
(n = 2775)
RADH
(n = 109)
Coronary arteries
2781 (89,7%)
2589 (93,3%)
107 (98,2%)
Aortoiliac arterial segment
255 (8,2%)
143 (5,2%)
-
Brachiocephalic arteries
62 (2%)
42 (1,5%)
-
Other
1 (0,03%)
1 (0,03%)
2 (1,8%)
The cases of catheterization failure and repeat radial artery punctures/catheterizations
are listed in Table 3.
Table 3. Repeat catheterizations and catheterization failure of forearm and hand arteries.
FRA
(n = 3099)
RAAS
(n = 2775)
RADH
(n = 109)
Catheterization/puncture failure
124 (4%)
71 (2,3%)
9 (8,3%)
Repeat (two or more times)
puncture/catheterization
320 (10,3%)
347 (12,5%)
12 (11%)
We analyzed the dependence of fluoroscopy time and absorbed radiation dose when
performing coronary angiography with different arteries of access. Fluoroscopy time with
FRA and RAAS had no significant differences (p≤0.01). Fluoro time rates were significantly
lower in RADH access as compared to FRA and RAAS approaches (Fig. 15). Notably,
RADH catheterization was performed by a limited number of experienced operators.

Fig. 15 Time of fluoroscopy (on coronary angiography) depending on access artery.
Note - 1 median values presented;
- 2 interquartile range presented;
Radiation dose analysis showed the same results (fig. 16).
Fig. 16 Radiation absorbed dose (during coronary angiography) variations depending on
access artery.
Note - 1 median values presented;
- 2 interquartile range presented;
Follow-up of forearm and hand arteries of access was performed in 32% of patients (fig.
17)
0
5
10
FRA [4,29-11,02] ² RAAS [4,31-11] ² RADH [3,31-6,02] ²
8,26 8,33
5,09
fluoro time, sec
0
500
1000
1500
FRA [703-1508] ² RAAS [749-1548] ² RADH [534-1095] ²
1197 1191 901
Rg ¹ dose
71% 63,6% 75,5%
29% 36,4% 24,5%
0%
20%
40%
60%
80%
100%
FRA (n=3009) RAAS (n=2775) RADH (n=109)
follow-up
no follow-up

Fig. 17 The results of follow-up of access artery.
The results showed higher frequency of post-catheterization occlusions of radial artery
after approaching to FRA (table 4).
Table 4. Frequency of post-catheterization occlusions of radial artery at forearm and at
hand.
Number of patients
at follow-up of access artery
Access artery occlusion
FRA (n=873)
4,2% *
RAAS (n=1009)
2,2 % *
RADH (n=27)
-
Note - * differences in rates of artery occlusion between FRA and RAAS catheterization
are significant in p ≤ 0,05.
Interesting results were obtained in RADH catheterization group. Local RAAS
occlusion with preserved blood flow of forearm radial artery was observed in 2% of cases;
FRA occlusion after catheterization of radial artery within the anatomical snuffbox was
observed in less than 0,5% of cases (fig. 18).
Fig. 18 Variants of occlusion involving RAAS and their prevalence.
Therefore it should be noted that after the catheterization of RAAS the prevalence of
FRA occlusion was reduced almost 10 times and the total number of occlusions was reduced
Access artery follow-up
RAAS (n=1009)
FRA occlusion (without
RAAS occlusion) –0,1% FRA and RAAS
occlusion –0,3% Local RAAS occlusion
with active blood flow in
FRA - 1,8%

twice. Encouraging results were obtained in RADH group where there were no reported cases
of radial artery occlusion. However, further observations are needed.
The analysis of the other acess-related complications showed no significant differences
between catheterization sites (table 5).
Table 5. Acess-related complications.
complications
FRA
RAAS
RADH
Haematoma > 10 cm
0,2%
0,2%
0,9%
Pulsatile haematoma (transfusion
needed)
˂ 0,1%
˂ 0,1%
-
Infection, arteriitis
0,1%
0,1%
0,4%
Dissection/rupture of access artery
0,2%
0,1%
0,9%
a/v fistula
˂ 0,1%
˂ 0,1%
-
Conclusion
The modern trend in population to a "younger" stable angina and the evolution of the
intervention techniques will inevitably lead to an increased number of repeat endovascular
interventions consequently requiring the repeat use of the same "access arteries", so we may
need to keep arterial access "safe";
Not only a mechanical compression of an access artery makes a contribution to post-
catheterization occlusion of the artery, but also does the impairment of arterial wall layers
during PCI;
Catheterization of RAAS has lower rates of occlusive complications as compared to
FRA;

The risk of RAAS occlusion due to the compression towards the "bone basement" still
remains;
Radial artery at the dorsum of hand is surrounded by soft tissues that poses a
background to a reduced risk of its occlusion during the compression with a hemostatic
bandage;
The post-catheterization stenosis of an access artery makes the repeat use of the artery
difficult although the antegrade blood flow in it may be preserved.
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