Peripheral Arterial Disease

Information Technology Services5/24/2019Disclosures None relevant to this presentationPeripheral Arterial DiseaseLeslie M Scoutt, MD, FACRProfessor of Diagnostic Radiology, Vascular Surgery& CardiologyMedical Director Non-Invasive Vascular LabYale School of MedicineOverview Clinical BackgroundNon-invasive testing with ABIs and PVRsArterial Doppler US of Native PeripheralArteriesSurveillance s/p InterventionsBackground Significant manifestation of atherosclerosisIncidence 15% in pts 50 yrs Risk factors 40 yrsSmoking DM HTHyperlipidemia Hyperhomocysteinemia Background Pathophysiology Oxygen delivery 2 0 arterial stenosis/occlusionClinical Presentation Poses significant risk forEarly intervention w/ lipid lowering andantiplatelet RxScreening at risk pt populations importantSigns & Sxintermittent claudication (10%), rest pain, nonhealing wound or foot ulcer pallor and pain w /elevation Limb ischemia “All-cause” and CVD mortality Assx pts have same risk of CVD & death M F pedal pulses 50% of pts assxor atypical SxDDx: neurologic and MSK diseaseDelay dxs progression Risk of CVD mortality (C) Copyright, 2000 Yale University. All rightsreserved.1

Information Technology Services5/24/2019Ankle Brachial Index Best screening modalityConfirm diagnosis, identify vascular etiologyin workup of leg symptoms ABI in symptomatic pts significant disease between the heart and theankleNORMAL ABI useful to exclude PADAnkle Brachial Index Useful to establish a baseline in pts withconfirmed PADGood test for serial studies cheap, fast, no significant riskindependent of daily variations in BPMonitor progression of diseaseMonitor efficacy of therapeuticinterventionsAnkle Brachial IndexInterpretation ABI 0.9 (1.0) NORMALThe lower the ABI, the more severe the PADthe more likely there is multifocal dxsABI 0.4 Critical Limb IschemiaHiatt WR. N Engl J Med 2001;344:1608-21TASC II Guidelines. Eur J Vasc Endovasc Surg 2007; 33: S1-S70 1.30Noncompressible1.00 – 1.29Normal0.91 to 0.99Borderline (equivocal)0.41 to 0.90Mild to moderate disease 0.40Severe disease (Risk for rest pain, ischemic ulcer, gangrene)Interpretation BPS the Rt and Lt arm in ABI of 0.15OR in ABI 0.10 PLUS change in clinical status(C) Copyright, 2000 Yale University. All rightsreserved.Performed in Sxpts with NL resting ABI 15-20 mm Hg diff is ABNL prox stenosis in artery w/ lower BPSProgression of Dxs on serial exams diff 20 mm Hg c/w subclavian stenosis in armw/ lower BP SBPS in DPA & PTA & Rt and Lt Exercise ABI differentiates vascular from pulmonary,cardiac, MSK causes of pain with exercisePt walks on a treadmill at 2 mph (3.2km/h), 10-12% grade until claudicationoccurs (or max 5 min)No treadmill?active pedal plantar flexiondon’t have pt try and walk around department get a treadmill . 2

Information Technology Services5/24/2019Exercise ABI: Interpretation in exercise ABI by 0.15-0.20 is diagnosticof PADPts with non-vascular causes of exerciserelated leg pain will have NL ankle pressureat rest and after exercise Segmental Pressures no changeIf exercise ABI is normal, PAD is effectivelyruled out Determine location of arterialstenosisGradient 20 mm Hg btwnsegments or Lt & Rt issignificantGradient 40 mm Hgsuggests occlusion proxtolower BPsMost use whichever is higherDP/PTLimitations itis/DVTHT/Diabetes/Vessel wall calcificationfalsely elevated ABIs ( 1.3 or PB s 200) can’t compress doesn’t effect PVR waveform Toe Brachial Index (TBI) HT may cause increased gradientsLow cardiac output may cause decreasedgradientsShort vs longTight stenosis vs occlusionFalse negative if good collateral flowPlethysmography Tracings(PVR)Used when ABI 1.3 or known diabetes Pitfallsdigital arteries usually spared the calcinosisthat affects more proximal arteriesTBI 0.7 is abnormalTBI 0.4 – 0.35, claudication likelyTBI 0.20 – 0.10, poor px for woundhealing(C) Copyright, 2000 Yale University. All rightsreserved.Rapid upstrokeSharp peakSlower rise timeDelayed peak, flat or roundedDicrotic notchDownslope bowed towardsbaselineLoss of dicrotic notchDownslope bowed away frombaseline3

Information Technology Services5/24/2019Grading stenosis: With increasing stenosis severity, there is loss of the dicroticnotch, time to peak increases and the wave forms become more flat inappearancePVR: Interpretation Normal Mild stenosisShould be symmetric RT to LTDampened waveform indicates proximalstenosisIf dicrotic notch is present, can excludesignificant proximal dxsModerate stenosisSevere stenosis1956 yo Male,Claudication62 yo w/ Non-Healing LT Foot UlcerLt SFA DxsNormal68 yo w/ Non-Healing LT Foot UlcerBilat inflow dxsSevere distalmicrovessel dxsLt Rt(C) Copyright, 2000 Yale University. All rightsreserved.68 yo w/ Non-Healing LT Foot UlcerImprovementon Lts/p intervention4

Information Technology Services5/24/201962 yo w/ Leg Pain: Exercise ABIArterial Doppler US Rt Multilevel DxsLt NLGrey scale, color and pulse DopplerAorta to ankle vs focused exam Ultrasound as Screening Test ProsInexpensiveReadily available Non-invasive No contrast ConsTime consuming Operatordependent Body habitus Calcified plaque ? Below kneearteries ? Target vessel US Technique 3-5 MHz, curved transducer: iliacs5-7 MHz, linear array: groin to ankleGray scale Narrowing, color aliasing, PSV, PSVRChange in waveformwidening of spectral envelopeloss of early diastolic flow reversal continuous forward diastolic flow (colorpersistance) Arterial Waveforms Post stenotic turbulencealiasing (turbulent flow)perivascular tissue vibrationPulsed Doppler to assess % stenosisDoppler US @ Stenosis calcified plaque, thrombusaneurysmsColor Doppler at least trifurcationComplete exam may take 1 to 1.5 hoursBetter than ABIs & PVRs for localizing,grading, and determining length ofperipheral arterial stenosesTardus parvus waveform indicatesproximal stenosis or collateral flow patternLow PSV and absent diastolic flowsuggests distal obstruction Or: age, compliance, vessel wallcalcification, cardiac output Diastolic flow indicates vasodilatation distal ischemia, infection or exercise30(C) Copyright, 2000 Yale University. All rightsreserved.5

Information Technology Services5/24/2019Normal PeripheralArtery Waveform TRIPHASICGrading Stenosis sharp systolic upstroke early diastolicflow reversal mid diastolicforward flow /- end diastolicflow thin spectralenvelope no turbulence ? 70%, 90%grading stenoses 50% is not importantAbsolute PSVStenotic/Prestenotic PSV ratios Spectral broadeningFindingModerate stenosisSevere stenosis This is an ESTIMATE!(50-70%)( 70%) Confounding Factors Clinically significant stenosis is 50%Peak Systolic Velocity (PSV)200 – 350 cm/s 350 cm/sPSV RatioPSV stenosis/PSV upstream2 – 3.5 3.5Plaque/NarrowingTandem stenosesAbundant collateralsInflow diseaseOutflow diseaseCardiovascular status, BPSeveral “charts”, none work perfectly don’t take them too literallygrayscale, color Doppler, SYMPTOMSColor BruitCourtesy Dr J Pellerito(C) Copyright, 2000 Yale University. All rightsreserved.63 yo Male with Leg PainSFA Occlusion6

Information Technology sisClaudication, Positive ABIClaudication, Positive ABIClaudicationClaudication: Tandem LesionsCFA Stenosis, ATA Occlusion(C) Copyright, 2000 Yale University. All rightsreserved.7

Information Technology Services5/24/2019Arterial Bypass Grafts:Complications 20-30% ABGs develop stenosis w/in the1st yr of surgeryProx & distal anastomoses VG along entire length 2 0 valve hypertrophy Retained perforators (in situ grafts)Synthetic grafts: PSAs at anastomosesSurveillance Detect and treat graft stenosis prior toocclusion: improves long term patencyConsists of interval history and physicalresting and post-exercise ABIs Doppler Ultrasound Baseline done in immediate postoperativeperiod and regular follow up ( 6 monthly)for at least 2 years Ultrasound CriteriaFindingPeak Systolic Velocity (PSV)PSV RatioPSV stenosis/PSV upstreamSlow flowPitfallsModerate stenosis(50-70%)200 – 350 cm/sSevere stenosis( 70%) 350 cm/s 2 – 3.5 3.5 45 cm/sEspecially if there is globallydecreased PSV and focallyincreased PSV Monophasic throughout graft(especially if it was triphasicpreviously) Waveform analysisIncreasing PSV on serial US examinationsSome use 300 cm/sGraft Surveillance(C) Copyright, 2000 Yale University. All rightsreserved.shorter interval if mild to moderate stenosis PSV at distal anastomosis common dueto vessel mismatchPSV is dependent on graft diameter change over time is importantPSV normally may be 45 cm/sec inbelow knee graftsMono-phasic waveforms, high or lowresistance, may be normal in syntheticgrafts esp ax-fem graftsOccluded Graft8

Information Technology Services5/24/2019Stenosis Proximal to GraftLeg Pain s/p ABGLeg Pain s/p ABGLeg Pain s/p ABGLeg Pain s/p ABGLeg Pain s/p ABG(C) Copyright, 2000 Yale University. All rightsreserved.9

Information Technology Services75 yo s/p ABG, NonHealing Ulcer in LT FootPost Angioplasty or Stent Post PTA PSVR 2 restenoses in 85%cases For stent use PSVR 3, PSV 300 cm/s,PSV 50 cm/s 5/24/2019PSA arising from Mid ThighGraftLeg Pain s/p 2 SFA Stentslesions may stabilizeGrayscale, color Doppler, change overtime, waveformsSFA Stent OK; BK Pop Occluded(C) Copyright, 2000 Yale University. All rightsreserved.Leg Pain s/p PA Stent10

Information Technology Services5/24/2019Leg Pain s/p SFA StentLeg Pain s/p SFA StentIn-Stent RestenosisRecurrent Pain s/p SFA StentAlgorithm: YNHHConclusionsABI, TBI,Segmentalpressures, PVR NormalAbnormalExercise ABI? ArterialDoppler,CTA, AngioABI 1.3IndeterminateABI/PVR 1 st step to evaluate for PADDoppler US helpful to screen nativeperipheral arteries for atherosclerosis, ifABI/PVR are abnormal (C) Copyright, 2000 Yale University. All rightsreserved. esp for ICU pts, renal failure, contrast allergySurveillance w/ US will clearly improvepatency rates in patients s/p ABGs,angioplasty and arterial stent placement11

ABI, TBI, Segmental pressures, PVR Normal Exercise ABI Abnormal? Arterial Doppler, CTA, Angio ABI 1.3 Indeterminate Conclusions ABI/PVR 1st step to evaluate for PAD Doppler US helpful to screen native peripheral arteries for atherosclerosis, if ABI/PVR are abnormal esp for ICU pts, renal failure, contrast allergy Surveillance w/ US will .