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MAV cerebrali Principi e tecniche di trattamento endovascolare Salvatore Mangiafico (AOU Careggi Firenze)

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MAV cerebrali

Principi e tecniche di trattamento endovascolare

Salvatore Mangiafico

(AOU Careggi Firenze)

Principi di trattamento

•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)

F, 23 y.o. Persistent severe headache, lateral right hemianopia

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

After two embolizations

1 month after the last treatment

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

Intra ventricular bleeding

Phase of single shot embolization

End of procedure:ICA and VA Simultaneus injection

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 .

• Maschio, 18 anni• Crisi comiziali

• Maschio, 18 anni• Crisi comiziali

• I tempo embolizzazione

Accesso bifemoraleDoppio microcateterismoApollo 3 cm

• II tempo embolizzazionepre-chirurgica: FINALI

ICA DX ICA SNICA SN

TC post-operatoria

ICA DX ICA SN

Angiografia post-operatoria

ICA SN

Angiografia post-operatoria

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

• M, 35 y.o.• Left Paraventricular and

paratrigonal hemorrhage 7 months before.

Arterial Access (pchoa)Venous access

Venous access : lateral atrial vein >sub ependimal parachoroidal vein

First step : intra-arterial embolization

Trans Venous onyx injection

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