108.Vascular Sx

Question 1

3 layers of an artery

Answer 1

TUNICS1. tunica externa or tunica adventitia (CT, fibroblasts, collagen)—important to resect to avoid inadvertent infolding into the lumen2. tunica media (smooth muscle, elastic)3. tunica intima (endothelial cells, fragile)** veins have the same layers but thinner media/muscle and no contraction and have valves

Question 2

arteries are found in all locations EXCEPT

Answer 2

hairepidermiscorneacartilagenails

Question 3

which veins carry oxygenated blood

Answer 3

pulmonary veins (bring oxygenated blood from lungs to left side of heart)umbilical vein carries oxygenated blood from dam to fetus

Question 4

another name for a double loop around a vessel for retraction

Answer 4

Potts double loopused for retraction and prevent hemorrhage in case of accidental vessel trauma

Question 5

ideal suture for vascular surgery

Answer 5

–swaged small needle/ round, circular taper point needle end–3-0 to 8-0suture with excellent knot holding capability and ease of handling with minimal inflammation–nylon, polypropylene (both monofilament)–small multifilament can be used when passed thru bone wax/mineral oil

Question 6

concern with synthetic grafts in vascular surgery

Answer 6

infectionthrombogenicex textile graft–Dacron, nontextile graft–PTFE

Question 7

characteristics of PTFE

Answer 7

polytetrafluoroethylene–hydrophobic (resists water, creates good seal)–biologically inert—relative thromboresistent–ductile and easy to use–cut to shape/length–strong and durable

Question 8

options to locate a vessel

Answer 8

1. palpation2. doppler color flow US

Question 9

what are the normal “marking” of adventitia of the perivascular sheath

Answer 9

the adventitial surface of the artery is marked by a characteristic vaso vasorum pattern perfusing vessels “white line” seen which facilitates plane of dissection

Question 10

if local anticoagulation is elected, what protocol is recommended

Answer 10

ice cold 2% lidocaine, heparin, 0.9% saline to flush the isolated segment at the arteriotomy/venotomy sitealso prior to closure, remove proximal inflow occlusion device to allow any air or clots to escape before placing final suturesMAKE sure to remove adventita to avoid infolding and potential thrombus formation or occlusion of lumen

Question 11

indications for systemic anticoagulation

Answer 11

—cardiopulmonary bypass—renal transplant–placement of vascular autogenous or prosthetics–adrenalectomy for adrenocortical tumorseither heparin given IV or heparin placed in plasma given before surgery and either IV, SQ post op if indicatedusually monitored with ACT (normal is < 150 secs but goal is 480sec for heparinization)

Question 12

recommendation for vessels that may be prone to recanalization

Answer 12

single transfixation ligature btwn two circumferential ligatures

Question 13

options for venotomy/arteriotomy incision

Answer 13

—longitudinal–good exposure, easily manipulation but may get narrow with closure–transverse–recommended in vessels smaller than 4 mm; incision should NOT extend 180 degrees of vessel circumference

Question 14

Kunlin’s technique for venotomy/arteriotomy closure

Answer 14

double swaged needle suturestarting the pattern with a horizontal mattress suture on each end

Question 15

three types of vascular anastomoses

Answer 15

1. end to end 2. side to side (not commonly done)3. end to side

Question 16

methods for end to end anastomosis

Answer 16

1. running continuous2. beveled or split edges3. triangulationavoid purse string effect with different continuous lines and allow release of proximal inflow occlusion to allow flow on incision

Question 17

method to create a hemodialysis site from a vein

Answer 17

deliberate surgical correction of an AV fistulaadding artery to vein creates turbulence within the vein making is larger and more resilientex. common carotid artery and external jugual vein OR brachial artery and cephalic vein type of end to end anastomosis

Question 18

indications for end to side anastomoses

Answer 18

1. feline and canine renal transplant2. grafting free vascularized segments of skin and musle3. systemic–pulmonary shunting (Blalock-Taussig) for treatment of metrology of fallot

Question 19

optimal angle for end to side anastomosis

Answer 19

< 30-45 degrees to functionally approximate vessels and minimize turbulence NOT FREQUENTLY POSSIBLEup to 75 degree is considered acceptable

Question 20

length of receiving vascular incision in an end to side anastomosis

Answer 20

length ~2x the donor vessel/graft (2:1) a ratio of 1:1 is commonly achieved

Question 21

suturing an end to side anastomosis

Answer 21

can bevel donor sidestart at “heel” firstuse double armed suture+/- plegets +/- dacron, PTFE reinforcementthen start at “toe”tie in the middle of each sideallow release of proximal inflow occlusion to allow release or air and thrombi before closure

Question 22

predominant autologous vascular grafting material in vet med

Answer 22

JUGULAR VEINharvested and kept MOISTlidocaine or papaverine may be applied to limit vessel spasmligated caudally, cannulated proximally and flushed with heparinized saline/lidocainethen ligate cranial segment and transect donor segment

Question 23

gold standard vascular imaging modality for endovascular surgery

Answer 23

ANGIOGRAPHY

Question 24

composition of a guidewire

Answer 24

outer stainless steel coil warpinner wire (mandrel) that taperdistal is softer and more flexibleusually have anti friction coatingcommon 0.035 inch

Question 25

major components for endovascular surgery

Answer 25

–angiography/fluoro–needle–guidewire–vessel dilator–vascular access or introducer sheath–catheter or stentSeldinger technique

Question 26

types of intravascular stents

Answer 26

—self expanding or balloon expandingself expanding are more flexible but cannot be over expandedballoon expanding can have variation in final diameter BUT may be prone to dislodging prior to reaching site (thus may need to use delivery sheath or guiding catherSE is better choice for tortuous areas and areas of significant motion (ie. trachea)

Question 27

stent materials

Answer 27

Stainless steel: braided, foreshorten, less radial strength, less useful in high motion areas, but RECONSTRAINABLE ex. WallstentNitinol: nickel and titanium alloy has thermal memory, less foreshortening, more predictable length and diameter

Question 28

indications for central venous catheter placement

Answer 28

—hemodynamic monitoring/pressures—frequent blood sampling—parenteral nutrition–medication administrationjugular access or PICC (peripherally inserted central catheter)–medial or lateral saphenousfor jugular placement measure to first rib or caudal ipsilateral tricep; should end in cava BEFORE RA

Question 29

indications for subcutaneous venous access port placement

Answer 29

companion port–keep HepLocked–serial sedation or anesthesia for long term wound mgmt or radiation therapy–administration of IV medications longterm (Ab or chemo)–serial blood samplingdisadvantages: kink, dislodge, hematoma, swelling, pain, bruising, need for surgical procedure placement (most are self limiting and prevented with good surgical technique/planning)

Question 30

what is embolotherapy

Answer 30

selectively occlude blood flow–obliterate/reduce tumor blood supply–occlude aberrant vascular anomalies (PDA, PSS)—stop or reduce hemorrhagemechanical: silk, coils, ductal occludersliquids: lipiodol, cyanoacrylateparticulate: polyvinvyl alcohol, gelatin microspheres, autogenous blood clot material

Question 31

what is embolectomy

Answer 31

removes blood clot to restore patencyarteriotomy, venotomy, or embolectomy cathetertx: feline aortic thromboembolism

Question 32

pathologic consequence to AV malformations

Answer 32

reduced systemic vascular resistancearterial pressures decrease and venous pressures increaseif the AV fistula is large enough, HR and SV will increase in an effort to maximize CO to maintain arterial pressuresmay lead to high output cardiac failure

Question 33

TX peripheral AV fistula

Answer 33

complete closure or removal of the aberrant AV communicationligation and division of artery proximal and sitar to communication is needed but venous ligation is not generally necessaryfailure to completely obliterate will need to formation of new communicationsalternative option: embolize area–cyanoacrylate embolization