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preview - MINERVA MEDICA
C. Setacci – R. chiesa – p. cao
Endovascular techniques in the
management of
aortic and peripheral
arterial disease
Edizioni Minerva Medica
ISBN: 978-88-7711-856-1
©2016 – EDIZIONI MINERVA MEDICA S.p.A. – Corso Bramante 83/85 – 10126 Turin (Italy)
Web site: www.minervamedica.it / e-mail: [email protected]
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means.
foreword
The technological improvement associated to increasing skills in treatment of aortic and peripheral vascular diseases increased life expectancy in vascular patients.
Every day vascular surgeons deal with patients and lesions more and more difficult. Moreover, new techniques are available
to manage most conditions.
Literature lacks of comprehensive data about endovascular tips and tricks to treat all the vascular challenges.
Skilled operators have to provide the best treatment for every patient in their daily medical routine. Their mission also includes teaching all the techniques and spreading their expertise. Aim of this book is to include in a unique text the physicians’ experiences, tips, tricks and the new technologies available.
This book is addressed to students, fellows and younger specialists in order to give them appropriate knowledge to face vascular pathologies providing an optimal treatment for every patient.
C. Setacci, R. Chiesa, P. Cao
Authors
Michele Antonello
Vascular and Endovascular Surgery Section, Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Italy
Alessandro Cappelli
Vascular and Endovascular Surgery Unit, Policlinico “Santa Maria alle Scotte”, University of Siena, Siena, Italy
Claudio Baldi
Vascular and Endovascular Surgery Unit, Policlinico “Santa Maria alle Scotte”, University of Siena, Siena, Italy
Gianpaolo Carrafiello
Interventional Radiology, Department of Radiology,
University of Insubria - Ospedale di Circolo and
Fondazione Macchi, Varese, Italy
Domenico Benevento
Vascular and Endovascular Surgery Unit, Policlinico “Santa Maria alle Scotte”, University of Siena, Siena, Italy
Estêvão Carvalho de Campos Martins
GVM Care and Research, Maria Cecilia Hospital,
Cardiovascular Department, Cotignola (RA), Italy
Luca Bertoglio
Department of Vascular Surgery, Scientific Institute San Raffaele Hospital, “Vita-Salute” University School of Medicine, Milan, Italy
Maria Pia Borrelli
Vascular and Endovascular Surgery Unit, Policlinico “Santa Maria alle Scotte”, University of Siena, Siena, Italy
Marco Calandri
Radiology Unit, Department of Diagnostic Imaging and Radiotherapy, AOU Città della Salute e della Scienza di Torino, Turin, Italy
Patrizio Castelli
Vascular Surgery, Department of Surgery and
Morphological Sciences, Circolo University Teaching
Hospital, Varese, Italy
Fausto Castriota
GVM Care and Research, Maria Cecilia Hospital,
Cardiovascular Department, Cotignola (RA), Italy
Fabrizio Chegai
Department of Diagnostic Imaging, Molecular Imaging,
Interventional Radiology and Radiotherapy, University
Hospital Tor Vergata - Department of Biomedicine and
Prevention, University of Rome Tor Vergata, Rome, Italy
Tommaso Cambiaghi
Vascular Surgery, “Vita - Salute” University, Scientific Institute Hospital San Raffaele, Milan, Italy
Roberto Chiesa
Department of Vascular Surgery, Scientific Institute San Raffaele Hospital, “Vita-Salute” University School of Medicine, Milan, Italy
Piergiorgio Cao
Vascular Surgery Unit, San Camillo-Forlanini Hospital,
Rome, Italy
Gianpaolo Cornalba
Diagnostic and Interventional Radiology, San Paolo Hospital, Milan, Italy
VIII
endovascular techiniques in the management of aortic and peripheral arterial disease
Carlo Coscarella
Vascular Surgery Unit, San Camillo-Forlanini Hospital,
Rome, Italy
Ciro Ferrer
Vascular Surgery Unit, San Camillo-Forlanini Hospital,
Rome, Italy
Alberto Cremonesi
GVM Care and Research, Maria Cecilia Hospital,
Cardiovascular Department, Cotignola (RA), Italy
Carlotta Ferretti
Vascular and Endovascular Surgery Unit, University Hospital IRCCS San Martino-IST, University of Genoa, Genoa, Italy
Valerio Da Ros
Department of Diagnostic Imaging, Molecular Imaging,
Interventional Radiology and Radiotherapy, University
Hospital Tor Vergata - Department of Biomedicine and
Prevention, University of Rome Tor Vergata, Rome, Italy
Gianmarco de Donato
Vascular and Endovascular Surgery Unit, Policlinico “Santa Maria alle Scotte”, University of Siena, Siena, Italy
Paola De Rango
Vascular Surgery Unit, University of Perugia, Ospedale S. Maria della Misericordia, Perugia, Italy
Marina Diomedi
Clinical Neurology, Department of Neuroscience,
University Hospital Tor Vergata, University of Rome Tor Vergata, Rome, Italy
Adolfo D’Onofrio
Department of Diagnostic Imaging, Molecular Imaging,
Interventional Radiology and Radiotherapy, University
Hospital Tor Vergata - Department of Biomedicine and
Prevention, University of Rome Tor Vergata, Rome, Italy
Andrea Doriguzzi-Breatta
Radiology Unit, Department of Diagnostic Imaging and Radiotherapy, AOU Città della Salute e della Scienza di Torino, Turin, Italy
Andrea Esposito
Vascular Surgery, San Filippo Neri Hospital, Rome, Italy
Sebastiano Fabiano
Department of Diagnostic Imaging, Molecular Imaging,
Interventional Radiology and Radiotherapy, University
Hospital Tor Vergata - Department of Biomedicine and
Prevention, University of Rome Tor Vergata, Rome, Italy
Luca Farchioni
Vascular Surgery Unit, University of Perugia, Ospedale S. Maria della Misericordia, Perugia, Italy
Roberta Ficarelli
Vascular Surgery Unit, San Camillo-Forlanini Hospital,
Rome, Italy
Roberto Floris
Department of Diagnostic Imaging, Molecular Imaging,
Interventional Radiology and Radiotherapy, University
Hospital Tor Vergata - Department of Biomedicine and
Prevention, University of Rome Tor Vergata, Rome, Italy
Paolo Fonio
Radiology Unit, Department of Diagnostic Imaging and Radiotherapy, AOU Città della Salute e della Scienza di Torino, Turin, Italy
Giuseppe Galzerano
Vascular and Endovascular Surgery Unit, Policlinico
“Santa Maria alle Scotte”, University of Siena, Siena, Italy
Giovanni Gandini
Radiology Unit, Department of Diagnostic Imaging and Radiotherapy, AOU Città della Salute e della Scienza di Torino, Turin, Italy
Roberto Gandini
Department of Diagnostic Imaging, Molecular Imaging,
Interventional Radiology and Radiotherapy, University
Hospital Tor Vergata - Department of Biomedicine and
Prevention, University of Rome Tor Vergata, Rome, Italy
Michele Giubbolini
Vascular and Endovascular Surgery Unit, Policlinico
“Santa Maria alle Scotte”, University of Siena, Siena, Italy
Franco Grego
Vascular and Endovascular Surgery Section, Department of Cardiac, Thoracic and Vascular Sciences,
University of Padua, Italy
Massimiliano Walter Guerrieri
Vascular and Endovascular Surgery Unit, Policlinico
“Santa Maria alle Scotte”, University of Siena, Siena, Italy
IX
Authors
Anna Maria Ierardi
Interventional Radiology, Department of Radiology,
University of Insubria - Ospedale di Circolo and
Fondazione Macchi, Varese, Italy
Mirko Menegolo
Vascular and Endovascular Surgery Section, Department of Cardiac, Thoracic and Vascular Sciences,
University of Padua, Italy
Giacomo Isernia
Vascular Surgery Unit, University of Perugia, Ospedale S. Maria della Misericordia, Perugia, Italy
Matteo Montorfano
San Raffaele Scientific Institute, Milan, Italy
Holta Kasemi
Vascular Surgery, San Filippo Neri Hospital, Rome, Italy
Irene Morelli
Vascular and Endovascular Surgery Section, Department of Cardiac, Thoracic and Vascular Sciences,
University of Padua, Italy
Daniel Konda
Department of Diagnostic Imaging, Molecular Imaging,
Interventional Radiology and Radiotherapy, University
Hospital Tor Vergata - Department of Biomedicine and
Prevention, University of Rome Tor Vergata, Rome, Italy
Daniele Morosetti
Department of Diagnostic Imaging, Molecular Imaging,
Interventional Radiology and Radiotherapy, University
Hospital Tor Vergata - Department of Biomedicine and
Prevention, University of Rome Tor Vergata, Rome, Italy
Marco Leopardi
Department of Vascular Surgery, Scientific Institute San Raffaele Hospital, “Vita-Salute” University School of Medicine, Milan, Italy
Matteo Orrico
Vascular and Endovascular Surgery Unit, Policlinico “Santa Maria alle Scotte”, University of Siena, Siena - San Filippo Neri Hospital, Rome, Italy
Nicola Mangialardi
Vascular Surgery, San Filippo Neri Hospital, Rome, Italy
Enrico Maria Marone
Department of Vascular Surgery, Scientific Institute San Raffaele Hospital, “Vita-Salute” University School of Medicine, Milan, Italy
Daniele Mascia
Department of Vascular Surgery, Scientific Institute San Raffaele Hospital, “Vita-Salute” University School of Medicine, Milan, Italy
Giulia Mazzitelli
Vascular and Endovascular Surgery Unit, Policlinico “Santa Maria alle Scotte”, University of Siena, Siena, Italy
Domenico Palombo
Vascular and Endovascular Surgery Unit, University Hospital IRCCS San Martino-IST, University of Genoa, Genoa, Italy
Enrico Pampana
Department of Diagnostic Imaging, Molecular Imaging,
Interventional Radiology and Radiotherapy, University
Hospital Tor Vergata - Department of Biomedicine and
Prevention, University of Rome Tor Vergata, Rome, Italy
Bianca Pane
Vascular and Endovascular Surgery Unit, University Hospital IRCCS San Martino-IST, University of Genoa, Genoa, Italy
Fabio Melchiorre
Radiology, San Paolo Hospital, Milan, Italy
Gianbattista Parlani
Vascular Surgery Unit, University of Perugia, Ospedale S. Maria della Misericordia, Perugia, Italy
Germano Melissano
Department of Vascular Surgery, Scientific Institute San Raffaele Hospital, “Vita-Salute” University School of Medicine, Milan, Italy
Maria Cecilia Perfumo
Vascular and Endovascular Surgery Unit, University Hospital IRCCS San Martino-IST, University of Genoa, Genoa, Italy
endovascular techiniques in the management of aortic and peripheral arterial disease
Michele Piazza
Vascular and Endovascular Surgery Section, Department of Cardiac, Thoracic and Vascular Sciences,
University of Padua, Italy
Gabriele Piffaretti
Vascular Surgery, Department of Surgery and
Morphological Sciences, Circolo University Teaching Hospital, Varese, Italy
Carlo Rabbia
Vascular Radiology, Città della Salute e della Scienza, San Giovanni Battista Hospital, Turin, Italy
Carlo Andrea Reale
Department of Diagnostic Imaging, Molecular Imaging,
Interventional Radiology and Radiotherapy, University
Hospital Tor Vergata - Department of Biomedicine and
Prevention, University of Rome Tor Vergata, Rome, Italy
Enrico Rinaldi
Department of Vascular Surgery, Scientific Institute San Raffaele Hospital, “Vita-Salute” University School of Medicine, Milan, Italy
Sonia Ronchey
Vascular Surgery, San Filippo Neri Hospital, Rome, Italy
Denis Rossato
Radiology Unit, Department of Diagnostic Imaging and Radiotherapy, AOU Città della Salute e della Scienza di Torino, Turin, Italy
Maria Antonella Ruffino
Department of Vascular Surgery, Scientific Institute San Raffaele Hospital, “Vita-Salute” University School of Medicine, Milan, Italy
Neil Ruparelia
Imperial College, London, UK - San Raffaele Scientific Institute, Milan, Italy
Umberto Ruzzi
Vascular and Endovascular Surgery Unit, Policlinico “Santa Maria alle Scotte”, University of Siena, Siena, Italy
Fabrizio Sallustio
Clinical Neurology, Department of Neuroscience,
University Hospital Tor Vergata, University of Rome Tor Vergata, Rome, Italy
Paolo Sbarzaglia
GVM Care and Research, Maria Cecilia Hospital,
Cardiovascular Department, Cotignola (RA), Italy
Eugenia Serrao
Vascular Surgery, San Filippo Neri Hospital, Rome, Italy
Francesco Setacci
Department of Surgery “P.Valdoni” Sapienza University of Rome - Policlinico Umberto I, Rome, Italy
Carlo Setacci
Vascular and Endovascular Surgery Unit, Policlinico “Santa Maria alle Scotte”, University of Siena, Siena, Italy
Giovanni Simonetti
Department of Diagnostic Imaging, Molecular Imaging,
Interventional Radiology and Radiotherapy, University
Hospital Tor Vergata - Department of Biomedicine and
Prevention, University of Rome Tor Vergata, Rome, Italy
Sara Spelta
Department of Vascular Surgery, Scientific Institute San Raffaele Hospital, “Vita-Salute” University School of Medicine, Milan, Italy
Giovanni Spinella
Vascular and Endovascular Surgery Unit, University Hospital IRCCS San Martino-IST, University of Genoa, Genoa, Italy
Paolo Stanzione
Clinical Neurology, Department of Neuroscience,
University Hospital Tor Vergata, University of Rome Tor Vergata, Rome, Italy
Matteo Stefanini
Department of Diagnostic Imaging, Molecular Imaging,
Interventional Radiology and Radiotherapy, University
Hospital Tor Vergata - Department of Biomedicine and
Prevention, University of Rome Tor Vergata, Rome, Italy
Stella Stella
San Raffaele Scientific Institute, Milan, Italy
Fabio Verzini
Vascular Surgery Unit, University of Perugia, Ospedale S. Maria della Misericordia, Perugia, Italy
contents
Ch.
1 Introduction … …………………………………………………………………………………………………………………………………………… 1
u
Basic concept of endovascular materials … ……………………………………………………………………………………………… 1
G. Gandini, P. Fonio, M. Calandri, A. Doriguzzi-Breatta, D. Rossato
uEquipment and logistic organization for endovascular procedures (OR vs. hybrid room) …
……… 8
G. Cornalba, F. Melchiorre, A.M. Ierardi, G. Carrafiello
Ch.
2 Diagnostics … …………………………………………………………………………………………………………………………………………… 17
uDiagnostic methods for vascular disease ………………………………………………………………………………………………… 17
M.A. Ruffino, C. Rabbia
uComputer based planning for endovascular treatment of aortic disease
OsiriX software … …………………………………………………………………………………………………………………………………………… 28
L. Bertoglio, S. Spelta, D. Mascia, R. Chiesa
uAquarius TeraRecon … …………………………………………………………………………………………………………………………………… 37
Ch.
Ch.
Ch.
Ch.
C. Ferrer, C. Coscarella, P. Cao
u
3mensio … ………………………………………………………………………………………………………………………………………………………… 44
B. Pane, G. Spinella, M.C. Perfumo, D. Palombo
3 Peripheral arterial disease: femoro-popliteal vessels …
……………………………………………… 46
F. Verzini, P. De Rango, G. Parlani, L. Farchioni, G. Isernia
4 Peripheral arterial disease: below the knee and below the ankle arteries … …… 71
G. Spinella, B. Pane, M.C. Perfumo, C. Ferretti, D. Palombo
5 Aortoiliac steno-occlusive disease … ………………………………………………………………………………………… 81
N. Mangialardi, S. Ronchey, A. Esposito, E. Serrao, H. Kasemi, M. Orrico
6 Epiaortic vessel disease … ………………………………………………………………………………………………………………… 97
A. Cremonesi, E. Carvalho de Campos Martins, P. Sbarzaglia, F. Castriota
XII
Ch.
endovascular techiniques in the management of aortic and peripheral arterial disease
7 Endovascular treatment of acute stroke …
………………………………………………………………………… 127
G. Simonetti, R. Floris, R. Gandini, E. Pampana, F. Chegai, V. Da Ros, A. D’Onofrio, S. Fabiano, D. Konda, D. Morosetti, C.A. Reale, M. Stefanini, M. Diomedi, F. Sallustio, P. Stanzione
Ch.
Ch.
8 Abdominal aortic aneurysms …
………………………………………………………………………………………………… 147
F. Setacci, G. Galzerano, G. de Donato, D. Benevento, M.W. Guerrieri, U. Ruzzi, M.P. Borrelli, C. Setacci
9 Thoracic aortic aneurysms …………………………………………………………………………………………………………… 161
R. Chiesa, E.M. Marone, D. Mascia, M. Leopardi, G. Melissano
Ch. 10 Thoracic dissection … ……………………………………………………………………………………………………………………… 177
R. Chiesa, L. Bertoglio, D. Mascia, T. Cambiaghi, E. Rinaldi
Ch. 11 Thoraco-abdominal aortic aneurysm … ………………………………………………………………………………… 190
C. Ferrer, C. Coscarella, P. Cao
Ch. 12 Peripheral aneurysms … ………………………………………………………………………………………………………………… 208
P. Castelli, G. Piffaretti
Ch. 13 P
eripheral artery disease: upper limb arteries and arteriovenous fistulas …………………………………………………………………………………………………………… 215
M. Antonello, F. Grego, M. Menegolo, M. Piazza, I. Morelli
Ch. 14 Endovascular treatment of aortic valve pathology ……………………………………………………… 225
S. Stella, N. Ruparelia, M. Montorfano
Ch. 15 New frontiers in endovascular surgery …
uAscending Aorta …
…………………………………………………………………………… 247
……………………………………………………………………………………………………………………………………… 247
N. Mangialardi, S. Ronchey, M. Orrico, A. Esposito
uThe aortic arch …………………………………………………………………………………………………………………………………………… 255
C. Ferrer, R. Ficarelli, C. Coscarella, P. Cao
uSteerable catheters …
………………………………………………………………………………………………………………………………… 262
E.M. Marone, R. Chiesa
uDrug eluting stents and bioresorbable scaffolds ………………………………………………………………………………… 268
N. Ruparelia, M. Montorfano
uNew design for carotid stent … ………………………………………………………………………………………………………………… 276
G. Galzerano, F. Setacci, G. de Donato, A. Cappelli, G. Mazzitelli, M. Giubbolini, C. Baldi, C. Setacci
uAnti-embolic devices for the aortic arch …
N. Ruparelia, M. Montorfano
…………………………………………………………………………………………… 280
Chapter 1
Introduction
Basic concept
of endovascular materials
G. Gandini, P. Fonio, M. Calandri,
A. Doriguzzi-Breatta, D. Rossato
More than every other field, endovascular procedures experienced in the last
40 years a tumultuous development, pioneering the innovation of the minimally
invasive medicine. This would not have
happened without the astonishing progress of materials that can be now used routinely. Today hundreds of types of guidewires, catheters, sheaths, balloons and
stents are available in order to perfectly
suit the needs of the operators. Their differences in terms of length, calibre, shape
and material allow the operators to reach
and perform the best endovascular treatment in every vascular district.
Conversely, the diameter of the internal
lumen is expressed in inches (generally
0.035-0.038’’), because it corresponds
to the unit of measurement of the guidewire that can be inserted into the lumen
of the needle.
Needles length generally ranges from 6
cm to 8 cm.
Three different types of needles are
available:
1) seldinger type: coaxial needle with
metallic spindle (Fig. 1.1A);
Fig. 1.1
NEEDLES
A
All endovascular procedures begin with
a vessel puncture. The tip of the needle
used for vascular punctures can be either conical or flute-beak shape.
The external diameter of needles is measured in Gauge (G); the most frequently
used needles range from 20 G (0. 91
mm) to 16 G (1.63 mm).
B
endovascular techiniques in the management of aortic and peripheral arterial disease
2) needle without spindle (Fig. 1.1B);
3) cannula: metallic spindle with external PTFE cannula.
The choice fully depends on operator’s
preference.
GUIDEWIRES
Guidewires are fundamental not only to
navigate the vessel and reach the target
artery, passing through the stenosis, but
also to exchange catheters and to support, giving stability and strength, all
the endovascular devices.
Guidewires can be divided depending
on:
1) caliber (Inches) and length (cm);
2) stiffness;
3) type of tip;
4) hydrophilic or not hydrophilic
(PTFE) coating.
Caliber and length
Caliber varies between 0.014” and
0.038” Inches. 0.035” is the calibre of
choice for standard endovascular proce-
Fig. 1.2
dures (example: iliac PTA or diagnostic
angiography); in order to cross tight stenosis or treat small size vessels (example:
infrapopliteal district), 0.018” or even
0.014” guidewires can be used.
Length of the guidewires depends on the
type and the site of the procedure. Standard length is 145 cm; however, 180200-260 cm guidewires are available in
order to allow a safe catheters exchange,
keeping the guidewire in the catheterized vessel (exchange guidewires).
PTFE coated guidewires
PTFE coated guidewires have been the
standard for endovascular therapies for
decades. They can have straight (Fig.
1.2A) or J (Fig. 1.2B) conformation and
the softer part of the tip (floppy) can
vary between 3 cm and 15 cm in length.
Nevertheless, they are characterized by
a limited fluidity, with a greater friction on the vessels than the hydrophilic
ones.
Stiff and SuperStiff are two types of
PTFE coated guidewires characterised
by elevated stiffness. Today their main
use is while exchanging catheters and to
give support and stability during the use
of different devices (in particular, covered stents and aortic endoprothesis).
Hydrophilic guidewires
A
B
Hydrophilic guidewires represented a
major breakthrough in the field of interventional radiology materials, and they
now easily allow procedures previously
considered impossible to perform.
They have an internal metal core (Nitinol), coated with a hydrophilic polymer,
and they can be straight (Fig. 1.3A),
angled (Fig. 1.3B) or shapable.
The main advantages of this kind of
guidewire are the flexibility and, most
of all, the smoothness; if properly soaked
in water, they allow to navigate any vessel, even if angled and tortuous, and to
01
Introduction Basic concept of endovascular materials
cross vascular stenosis. An intrinsic limitation to hydrophilic guidewires is the
poor support and stability they can give
to the devices.
Over the years a “stiff” variant has been
introduced, offering more support for
the insertion of catheters or other devices, maintaining the same smoothness.
A
SHEATHS AND GUIDING
CATETHERS
B
Sheaths
After the arterial puncture, sheaths are
placed over the guidewire, in order to
minimize the risk of scarring and damage. Sheaths can be used to introduce or
remove any catheter or other kind of device, without traumatism on the artery
wall. They are usually provided with a
valve, to avoid blood reflux. Moreover,
they are equipped with a lateral way,
with a two-way tap, allowing irrigating
the lumen of the sheath and inject medium contrast.
These devices are segments of catheters (ranging from 10 cm to 100 cm of
length), with a very thin tip, covered with
a shorter PTFE sheath (Fig. 1.4A, B).
Tips can be straight or shaped differently (HS, RDC). Recently, steerable
sheaths are also available.
In some cases, sheaths can be also coiled
reinforced in order to give resistance to
kinking and compression.
The reported caliber (ranging from 4 Fr
to 14 Fr) corresponds to the diameter of
the lumen (internal caliber) and coincides with the maximum caliber of the
devices that can be subsequently used.
Particular vascular introducer sheaths are
used for the insertion of aortic endografts,
both thoracic and abdominal, similar to
those already described, but with a much
bigger diameter (up to 26 Fr); in these
cases, surgical exposure of the artery or
proper percutaneous closure devices are
needed in order to achieve haemostasis at
the end of the procedure.
Fig. 1.3
Guiding catheters
Catheters most frequently used range
from 6 Fr to 8 Fr, allowing to deliver balloon catheters and stents (ranging from
5 Fr to 7 Fr) to the site of the lesion. Using Y-shaped taps, it is possible to check,
through the infusion of contrast agent, the
correct positioning of the balloon catheter/
stent before releasing it; it’s also possible to
control the final result of the procedure
without changing the catheter.
CATHETERS
Sliding along the guidewires, catheters
can navigate the vessels and reach the
target artery. They can be classified depending on:
1) the outer diameter (measured in
French), which varies from 4 Fr to
12 Fr;
A
Fig. 1.4
B
endovascular techiniques in the management of aortic and peripheral arterial disease
C
A
B
E
D
Fig. 1.5
Fig. 1.6
A
2) the internal diameter; it is measured
in inches;
3 the length, which varies from 60 cm
to 125 cm;
4) the material; they can be made with
PTFE or hydrophilic coating; PTFE
gives remarkable stiffness and proper
navigability in the vessels; hydrophilic catheters give the operator good
twist control and excellent navigability of the vessels; as for hydrophilic
guidewires, it is essential to soak the
outer surface prior to their use.
5) the conformation of the tip (Fig. 1.5):
the choice between different types
of curvature depends on the type of
vessel to be catheterized; the most
frequently used are “Cobra” (Fig.
B
1.5A) and “Shepherd Hook” (Fig.
1.5B) and “Simmons” (Fig. 1.5C)
(for renal arteries, celiac trunk and
superior mesenteric artery), “Headhunter” for supra aortic trunks, “Berenstein” and “Vertebral” (Fig. 1.5D)
for carotid and vertebral arteries, and
“Contralateral” for the iliac bifurcation.
Pig-tail tips (Fig. 1.5E), with their multiple holes, are useful in order to perform
diagnostic angiography in large vessels.
In order to perform superselective catheterization of small peripheral vascular
branches, coaxial catheters (microcatheters) are now available. They have very
small external caliber (1.2-3 Fr) and can
slide along guidewires of small caliber
(from 0.014 to 0.010 inches); in turn,
these micro-catheters can advance into
the lumen of standard diagnostic catheters, which carry guideswires of 0.035
inches. A few examples of their uses are:
treatment of arterio-venous malformation, selective hepatic arterial chemoembolization and, in the peripheral
district, the treatment of vascular malformations.
BALLOONS
Balloon catheters used today are derived
from the model proposed by Grüentzig
in 1974 and they represent the development of the system for vascular dilatation proposed in 1964 by Charles Dotter. These catheters have an inflatable
balloon at the distal end: the balloon is
positioned at the level of the vessel stricture and it is inflated in order to dilate
the narrowed segment and re-establish
an adequate blood flow. These balloons
are made of polyester, placed over nylon
or hydrophilic catheters connected to a
side way where contrast medium can be
injected or aspirated in order to inflate
or deflate the balloon (Fig. 1.6A, B).
Balloon catheter can be classified depending on:
01
Introduction Basic concept of endovascular materials
1) balloon diameter (ranging from 1.5
mm up to over 20 mm) and length
(ranging from 2 cm up to over 20
cm); in clinical practice, most commonly used diameters are:
–2-3.5 mm in the infrapopliteal
district;
– 4-7 mm in the carotid district;
–4-6 mm in the superficial femoral, popliteal and renal arteries;
– 8-12 mm in the iliac vessels;
2) Behaviour of the balloon to different
inflation pressures:
–compliant balloons (relaxing
gradually to the increasing pressure): today, one of their most relevant usage is the remodelling of
the endoprosthesis after endovascular aneurysm repair (EVAR);
for these procedures are now
available trilobe balloon catheters
to avoid the blood flow interruption during the inflation;
–semicompliant balloons and not
compliant balloons; for these
two kind of balloons an inflation nominal pressure and a rated
burst pressure are strictly reported
on the packaging of each device; a
manometer is therefore required;
3) Relation between guidewires and
balloon catheters:
–catheters “over the wire” in which
the catheter runs over the entire
length of the guidewire, with remarkable pushability;
–rapid exchange (RX) systems, in
which the catheter slides along
the guidewire only in the distal
segment for about 20 cm, and
then it exits through a side hole.
The advantages of RX are their
caliber and their shorter length in
comparison to the “over the wire”
type, which allow to more quickly exchange materials and to cross
very tight stenoses easily.
RX systems are used especially in procedures in the carotid and splacnic vessels,
where no elevated pushability is needed.
In recent years, formerly in coronary
interventions but nowadays also in the
peripherical ones, drug coated balloon
has emerged has a therapeutic option in
order to avoid the restenosis. They release antiproliferative drugs in order to
reduce the neointimal proliferation.
STENT
Metallic stents have particular structures, consisting of twisted metal filaments, and they can be placed in vessels,
in case of stenosis, to reconstitute and
keep a regular patency.
As mentioned, this area experienced a
rapid development of materials, with
always more dedicated devices (carotid,
femoral and infrapopliteal district).
The different types of stents are made
of biologically inert and non-allergic
material; Cobalt-Chromium (“medical” steel) and Nitinol (nickel-titanium
metal alloy) are the most frequently
used materials. Moreover, depending
on the metal filaments design, stents
can be more rigid but with a more effective plaque coverage (close cell) or
flexible but with a higher embolisation
risk (open cell). The choice between
these different features, of paramount
importance especially in the sovraortic
arteries, relies on several aspects: the tortuosity of the vessels, the typology of the
plaque, the operator’s preference.
As well as balloon catheters, stent delivery
systems can be “over the wire” or RX.
The most relevant classification is based
on the characteristics of stent expansion.
This includes:
– self-expandable stents (with shape
memory);
– mechanically expandable stent with
a balloon catheter.
Self expandable stent
They are usually made of Nitinol and
they can be expanded up to a predeter-
endovascular techiniques in the management of aortic and peripheral arterial disease
Covered stent
A
B
Fig. 1.7
mined caliber. They are contained in
a coaxial system, covered by an outer
membrane: the progressive retraction
of the external brace removes the membrane and allows the expansion (Fig.
1.7).
Compared to mechanically expandable stents they have the advantage of a
greater length (now up to 20 cm) that
allows recanalizing vascular segments
with long occlusions or vessels under
mechanical stress (torsion, flexion, elongation, compression) like the femoral
district. The caliber of the release systems is variable depending on the final
diameter of the stent (with a relationship of direct proportionality) and on
the guidewire caliber; stent of small
caliber and 0.018 lumen of the delivery
system can be mounted on systems of 4
Fr, whilst those of higher calibre (0.035
inches) can bear systems of up to 6 Fr.
Balloon expandable stent
They are made of steel or other alloys;
unlike the self-expandable stents they
do not have shape memory, but they are
dilated by inflating a balloon and modelling them to the walls of the artery.
They are usually pre-mounted on a balloon catheter, which is subsequently
removed once the prosthesis has been
anchored. Once expanded, these stents
have high recoil resistance. Compared
to the self expandable stents, the delivery system of balloon expandable stent
has higher diameter (1 or 2 Fr more).
They are usually used in the treatment
of straight and segmental stenosis of
iliac or renal vessels or vascular district
with low mechanical stress in order to
avoid the stent fracture.
They can be self-expandable or balloon
expandable stent with a skeleton encapsulated in two or covered by one ePTFE
layer/s. They are usually used in case
of bleeding, A-V fistula, aneurysms or
completing the sealing areas of the iliac
branches of aortic endografts. Compared to bare stents, the delivery system
has higher diameter and they need large
calibre introducers (more than 7 Fr).
Flow diversion stents
These multi-layer stents reduce the extra-luminal turbulent flow, induce slow
and laminar flow determining thrombosis of the aneurysmatic sac. They are
widely used in the intracranial district
in the treatment of cerebral aneurisms
and they are already commercialized
both in the peripheral and thoracic-abdominal aortic endovascular aneurysm
repair. Virtually, the great advantage of
these stents is represented by the exclusion of the aneurysmatic sac with continuous patency of the collateral vessels
originating from the latter, without
needing to use fenestrated or branched
custom-made endoprosthesis.
DRUG ELUTING STENTS AND
ABSORBABLE STENTS
In order to avoid the intimal hyperplasia
and to reduce the risk of restenosis, drug
eluting stent (DES) are now available.
They are characterized by the release,
once implanted, of antiproliferative and
immunosuppressive drugs.
These devices, derived from the coronary interventions, are constituted
by three elements; the stent, a coating
polymer that contains the drug, and the
drug that is released, generally during a
period of some weeks. Frequently used
drugs are paclitaxel, which inhibits cell
replication, and sirolimus, an inhibitor
01
Introduction Basic concept of endovascular materials
of cell growth and of inflammatory cytokines expression. Self-expandable nitinol stents are also available, dedicated
to the superficial femoral artery, with a
direct release of paclitaxel without the
intermediation of polymers.
Another technological innovation could
be represented by absorbable stents,
whose structure is made of collagen or
special polymers such as polylactic acid,
that are already used for absorbable sutures. Currently they are tested for coronary interventions, with encouraging
results; however, these results need confirmation in order to extend their usage
in the peripheral district.
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