mav cerebrali principi e tecniche di trattamento endovascolare · mav cerebrali principi e tecniche...
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MAV cerebrali
Principi e tecniche di trattamento endovascolare
Salvatore Mangiafico
(AOU Careggi Firenze)
•The AVM is a complex system of connection between the arterial and the venous cerebral circulation
•The nidus and the venous cerebral drainage have not only an anatomic continuity but also a hemodynamic one
•Changes of the bAVM’s flow have effect on perinidal zone (neo-angiogenesis, pial recruitment) and on the cerebral vein (ectasia, varix, stenosis) and changes of the cerebral draininig veins have effect inside the nidus
Brain and AVM are interdependent
(their relationship is a condition of hemodynamic balance)
MECCANISMI FISIOPATOLOGICI ed evoluzione della MAV
Nidus pressione inferiore alla P
feeder( ipotensione nidale )
NIDUS
Alta velocità, pulsanti
Pressione aumentata
direttamente
proprzionale all’
aumento di portata
(Volume di shunt
dimensioni del nidus e
angioarchitettura)
Pressione
BassaPerdita della
autoregolazione
Feeder Vena emissaria
ipotensione ed alto flusso Ipertensione
turbolenza
Turbolenza
Dilatazione
Aneurismi flusso
dipendenti
Aneurismi
intranidali
Varici,Tortuosità
stenosi
Reclutamento
di feeder
La reazione del cervelloL’importanza dell’ambiente ambiente peri nidale
Nell’area perinidale:riduzione della pressionearteriosa nei feeder arteriosi associata ad unincremento della pressione venosa possono portarealla riduzione della pressione di perfusione delterritorio attorno al nido
Ipopoefusione critica non infartuale , Neo angiogenesi •Proliferazione vasodilatazione capillari perinidali•Apertura di micro shunt in connessione con il nidus
Reclutamento rete capillareperinidale
La riduzione della pressioneIntranidale
Il tessuto Cerebrale perinidale è il territorio di confine tra Emodinamicadella Mav ed emodinamica del Cervello
during the embolization the bAVM moves from a
condition of hemodynamic balance to an
hemodynamic perturbation that might be reversible
or not, depending on the possibility to reach a new
hemodynamic equilibrium
The hemodynamic modifications
are a complex and multifactorial
phenomenon, not necessarily and
exclusively secondary to the
venous outlet restriction, that may
be cosidered its visual
manifestation
(epi-phenomenon)
• Feeder occlusion:
inflow reduction
• Venous occlusion:
outflow reduction
• Partial nidal occlusion:
modification of intranidal
microcirculation
The hemodynamic stress moves from
the center of the nidus to its periphery
The Periphery of the nidus is
the weak point of the embolization
• Great attention must be paid to periferical unoccluded
nidal residu during the outflow restrinction
• The «Venous attach » must start only when the nidal
perifery is completely disconnected ( filled)
• Periferical devascularization is better reached with
multiple trans arterial microcatheterization (Plurifocal
concentic embolization)
Post-treatment hemorrhages are expression
of an irreversibele loss of hemodynamic balance
(disequilibrium) that leads to the rupture of
perinidal dilatated capillary network
Bleedings may occur without quantitative or
qualitative (flow velocity) modifications of the
venous drainage
37 year-old female, seizures and progressive left hemiparesis.2 previous embolizations in Lyon followed by radiosurgery
Delayed bleeding
In large bAVMs extensive embolization , also without signs of venous flow stagnation,
may create hemodynamic imbalance and promote delayed bleeding
The haemodynamic brain-AVM tolerance (naturally occurred or
induced by embolization) depends on the pattern of the venous
drainage that is related to its anatomical localization
Cortical Veins
superficial system
Sulcal AVM
(Cortical Pial AVM)
Gyral AVM
Deep scissural AVM
“junctional AVM”
basal Ganglia AVM
Deep venous
system
(ICV, RV)
Sub cortical
( superficial medullary veins)
Trans medullary veins
Anasthomotic medullary veins
Zone of venular interconnection
Paraventricular (deep medullary veins)
• Compenso emodinamico efficace
reclutamento di altre vene emissarie
significativa riduzione del flusso di shunt portano
al recupero della condizione di equilibrio MAV-Cervello
• Compenso emodinamico insufficiente
Condizioni insufficienti di controllo dell’iperpressione
Intranidale portano allo squilibrio emodinamico
progressivo con perdita irreversibile della omeostasi
sino all’ emorragia intra o post procedurale ( immediata
o a distanza)
Embolization of AVM should be obtained balancing
Venous and nidal occlusion
Nidal occlusion
Venous occlusion
the origin of the emissary vein
becomes the hub of the embolization
trans arterial embolization
The main problem is: how to balance the nidal occlusion
and the draining vein occlusion?
1. By respecting the patency of the emissary vein until the complete occlusion of the
nidus is completed
1. By staging the embolization and the feeder occlusion
2. By Multiple arterial perpherical access ( perpherical devascularization)
3. By Increasing nidal embolic petretaion despite the feeder’s reflux ( short and
dense plug cooker pressure tecnique )
Double microcatheterization
1
2
1
2
Double microctheterization and alternate onyx injection allows a simultaneous different spatial access
to nidus vascular structures; increase the control of intravenous progression reducing the total time
of the procedure
Emissary vein is the compass of the endovascular
treatment with onyx
the occlusion of the vein should be
controlled and balanced with the
progressive occlusion of nidus
• Intranidal origin of the emissary vein (head of the vein)
( typology of vein – nidal junction )
• Junction between feeder –nidus
• Primary and secondary veins
Converging pattern
(Caput medusae )
Serial Longitudinal pattern
(Along the entire vein)
Arteriolo-venous shunt
Retrograde (from occluded
head of vein )
filling of arteriolar feeders
Head of vein
Body of intranidal
draining vein
Retrograde filling of converging arterial feeders
from head of the Intranidal vein
•Intranidal origin of the emissary vein Head of vein
Strategy and indications to cure
endovascular cure (100% occlusion )
• BAVM less tha 10 cc nidal volume
Sigle shot
• BAVM between 10- 20 cc nidal volume
• multi step embolization ( 2 or 3)
• Surgical Stand by during the last embo
• Immediate surgery if BAAVM is nont fully occluded
Strategy and indications to cure in BAVMs
more than 20cc nidal volume
Radiosurgery
• Staged embolization
with final nidal occlusion
less tha 60 % followed
by delayed RS
surgery
• Target embolization plus
surgery
• Staged embolization
with Immediate
surgery if nidal
occlusion is more than
80%
Equilibrio
Disequilibrio
Rottura
Mav
alto flusso
(FAV)
Large (?)
Programmate
3 procedure
Valore
Critico
embolizzazione
Completa o
Chirurgia non
dilazionata
Completa
Esclusione Emodinamica
Guarigione
embo
emboembo
Embo
Rottura
Mav residua
Complicanza
Chirurgia
Precoce
GUARIGIONE
La prevenzione delle complicanze emorragiche può
essere cercata unicamente attraverso un timing di
trattamento che anticipi la rottura .
Tecniche di embolizzazione
• Embolizzazione centripeta ( trans artrial)
• Embolizzazione centrifuga ( trans venous)
Trans-venous approach
«Centrifugal embolization»
The embolizing agent is injected from the center of the AVM The nidal
occlusion occurs from the center to the periphery of the nidus
The migration of the embolizing agent along the draining veins is well
controlled : the microcatheter is the marker of the course of the
vein
Trans Venous onyx injection
When the head of vein is plugged
the Onyx progression towards
the plexiforn nidus is fast and
extensive and the control of the
progression of onyx along the
distal vein is under control
Arterial Access (pchoa)Venous access
Venous access : lateral atrial vein >sub ependimal parachoroidal vein
conclusioni
• L’embolizzazione di una mav cerebrale un segue il
principio fondamentale dall’equilibrio emodinamico
–mav cervello
• La tecnica e la stategia di trattamento devono tenere
conto dei fattori che determinano la complessità
emodinamica della mav ( architettura-localizzazione)
• Le vene hanno ruolo centrale nella efficacia e
sicurezza della procedura