Journal meetingTrauma Department of PRS in CGMH

11.17.2009R4 Pang-Yun Chou, MDR4 Pang-Yun Chou, MD

Prof. Chih-Hung Lin, MDProf. Chih-Hung Lin, MD

November, 2009, PRSNovember, 2009, PRS

Introduction

• Evolution– Random-pattern flaps– Fasciocutaneous flaps– Myocutaneous flaps– Perforator flaps

• Manchot, Salmon, Cormack, Lamberty, Taylor, Palmer, Morris, Tang…

• Ultimate goal of reconstruction– Match optimal tissue replacement– Minimal donor-site expenditure– Maintain function

Perforator flaps

Perforator flaps

• Koshima– Began in 1989

• inferior epigastric artery skin flap with the rectus abdominis muscle for reconstruction of floor-ofmouth and groin defects

• Br J Plast Surg. 1989;42:645–648Br J Plast Surg. 1989;42:645–648

– Large skin flap• Survive without muscle• Based on a single perforator

• Kroll and Rosenfield– Perforator flaps

• Blood supply from MC flap, without deteriorating donor site

Perforator flap

• Clinically, harvested as– Pedicle perforator flap– Free flap

• Over 350 perforatorsOver 350 perforators in body– Diameter and length of source artery– Location of pivot point

• Perforators– Direction– Axiality of flow

Perforators

• Taylor and palmer– Angiosome concept

• Source artery perforators itself• Dynamic vascularity of perforator flapsDynamic vascularity of perforator flaps• Limiation of static image

– Vascular distribution and flow characteristics

• Perforators– Axiality of blood flow– Connections with adjacent perforators– Subdermal plexus and fascia contribution

Perforasome

• 3 years research

• 217 flaps, totally

• 40 fresh cadavers40 fresh cadavers

• Dissect by loupe

• Methylene blue

Texas Southwestern Medical CenterTexas Southwestern Medical Center

Materials and Methods

• Anterior trunks– Internal mammary artery, superior epigastric artery, deep inferior

epigastric artery, and supraclavicular artery perforator flaps

• Posterior trunks– Thoracodorsal artery, posterior intercostal artery, lumbar artery,

and superior and inferior gluteal artery perforator flaps

• Upper extremity– Ulnar artery, radial artery, and posterior interosseous and the Qu

aba flaps

• Lower extremity– ALT, AMT, ATA, peroneal artery, and PTA perforator flap

Flap harvesting technique• Trunk

– Harvested from midline to midaxillary line– Anterior trunk

• 26 IMA flaps – supraclavicular to costal chondral margin• 60 DIEP flaps• 13 SEAP flaps – superior epigastrium to lower

– Posterior trunk• TDA flaps• LA flaps – T12 to iliac crest

• Extremity– Skin incisions

• ForearmForearm -- made opposite the source artery• ALT, AMTALT, AMT – groin crease to supra-patellar region• Lower legLower leg – circumferential skin dissection

Dynamic 4D-CT

• 4D-CT angiography– 3D-CT angiography + TIMETIME

• Scanned with contrast media just injected• Characteristics and distribution of vascular perfusionvascular perfusion

• Flaps– Placed skin downward

• Prevent pressure on the pedicle• Minimize the risk of ↑resistance during perfusion

• Contrast media– Heated to 373700 ↓Viscosity, ↑ Vascular filling– 2 to 5 ml/flap

Static 3D-CT

• Barium-gelatinBarium-gelatin mixture– 100ml N/S to 404000 + 3g gelatin– Slowly adding 40g barium sulfate– Vascular tree was saturated– Flaps frozen at least 24 hrs before CT scan

• Static 3D– Branching patterns of perforators– Characteristics of linking vessels

• Dynamic 4D– Axiality or preferential direction of flow

Results

• PerforasomePerforasome– Each perforator has its

own unique vascular arterial territory

• CT image– Multiple direct linking v

essels– Direction of flow

PerforasomePerforasome

First principle

• Two mechanism– DirectDirect linking vessels

• Communicating directly from one perforator to the next• Within the suprafascial and adipose layer

– Indirect Indirect linking vessels• Recurrent flow through the subdermal plexus

Linking vessels

• Linking vessels– Multiple perforasomes– To one another

• Flow through– Communicating branCommunicating bran

chesches– BidirectionalInjury to direct or indir

ectPerfusion maintainedPerfusion maintained

Dynamic 4D-CTDynamic 4D-CT

ALT to AMT, By Large direct linking vesselsALT to AMT, By Large direct linking vessels

AMT to ALT, Reverse perfusion, bi-directionalAMT to ALT, Reverse perfusion, bi-directional

ALT to AMT, By LVs, communicating branchesALT to AMT, By LVs, communicating branches

AMT to ALT, bi-directionalAMT to ALT, bi-directional

Sub-dermal plexus

• TaylorTaylor– Choke vessels– Indirect linking vessels– Recurrent flow from

sub-dermal plexus

Indirect linking vessels

• Perforators– Oblique branch, Vertical branch to subdermal plexus

• Indirect linking vessels– Recurrent flowRecurrent flow from the subdermal plexus

Lateral viewLateral view

Communicating branches

• Communicating branches– Coronal, sagittal, and transverse planes– Confer a protective mechanismprotective mechanism to ensure vascular flow to skin

Transverse viewTransverse view

Second principle• Flap design, Skin paddle orientation

– Based on the direction of linking vesselsdirection of linking vessels• Axial in extremity

– Parallel to the axis of the limbs– Flaps designed in parallel to axis of linking vessels

• Perpendicular to the midline in trunk– TDA flap (latissimus dorsi muscle fibers), IMA flap– Perforators follow a vertical row distribution

» Have contra-lateral ones– Flow away from the midline for lateral vascularity– Ant. and posterior midlines of trunk

» Heavily populated in perforators

Axiality

Thoracodorsal flapThoracodorsal flap

Forearm flapForearm flap

Lower legAnterior legAnterior leg Posterior legPosterior leg

Cross midlineCross midline Follow axiality of limbFollow axiality of limb

Trunk

Linking vesselsLinking vessels

Perpendicular to midline of trunkPerpendicular to midline of trunk

Abdomen

Transverse abdominal skin flapTransverse abdominal skin flap

Linking vessels, perpendicular, Linking vessels, perpendicular, bi-directional fashionbi-directional fashion

Back

Perpendicular, cross midlinePerpendicular, cross midline

Third principle

• Preferential filling of perforasomes– Within perforators of the same source artery

– Followed by perforators of adjacent source arteries adjacent source arteries• DB-LFCA AMT superficial FA perforasomes• Vascular filling, density maximized, then spread-out

– Single large perforatorsSingle large perforators from a source artery• Medial circumflex femoral artery• Less axial vascular distribution

Preferential filling

Adjacent source arteriesAdjacent source arteries

Fourth principle

• Mass vascularity– A perforator adjacent to an articulation

• Directed away from same articulation

• Radial A. perforator flap

– A perforator at midpoint between two articulations, or in trunk• Multi-directional flow distribution

Direction of flow• Vascular density

– ↓distally away from• Midline of trunk• An articulation

• Orientation of LV– Orientation of vascular flow

• Perpendicular to midline• Parallel to limb axis

• Perforator locationPerforator location– Flap design– LVs between two perforators

• Bi-directional flow• Protection against injury

Discussion

• Each perforator– Its own vascular territory, PerforasomePerforasome– Multidirectional flow pattern– Highly variable and complex

• Single perforator–based flap reconstructions– Knowledge of individualindividual perforator vascular anatomy

• supersedes that of source artery vascular anatomy

• Perforasomes are linked– Direct and indirect linking vessels– Communicating branches– ProtectionProtection from ischemia and vascular injury in case of trauma

Discussion

• Perforator flap harvested– All branches from the source artery are ligated– Results in hyperperfusionhyperperfusion ↑ ↑ vascular filling pressures

• Dilate the perforator itself• Allow extensive interperforator flow

– LVs, higher than normal filling pressures• Capture additional adjacent perforator vascular territories

• Perforator flaps designed at a midpoint – Designed in multiple fashions

• Multidirectional perforator flow distribution

– Dense fibrous septae/ligamentous attachments over articulation• Maintain skin stability and draping during flexion and extension• Perforators directed away from the articulationaway from the articulation

Conclusion

• Every perforator has the potential – Become either a pedicle or a free perforator flap

• HyperperfusionHyperperfusion of a single perforator – Capture multiple adjacent perforasomes– Large perforator flaps based on a single perforator

• Additional adjacent perforasome territories– Captured through direct and indirect LVs by hyperperf

usion

Conclusion

• Perforasome theoryPerforasome theory

– Provides additional insight into the mechanisms of perforator flap vascularity

– Serves to facilitate the understanding, design, and clinical use of both free and pedicle perforator flaps

Thanks for your attention!