Amol gulhane -peripheral vascular disease

Dr amol gulhane DNB resident CARE hospitals , hyd

inner layer of endothelium (intima) middle layer of connective tissue, smooth muscle and elastic fibers (media)outer layer of connective tissue (adventitia)

have smooth muscles that contracts & relaxes to respond changes in blood volume.

charac. by a reduction in blood flow and hence 02 through the peripheral vessels

when the need of the tissues for 02 exceeds the supply, areas of ischemia and necrosis will develop

 Factors that can contribute to the development of peripheral

vascular disorders : atherosclerotic changes thrombus formation embolization coagulability of blood hypertension inflammatory process/infection

Atherosclerosis

Thrombosis or embolism

Aneurysm

Intimal dissection

Pseudo-aneurysm

Arterio-venous fistula

Arteritis

Entrapment syndrome

Cystic adventitial disease

Most common cause

Arterial Insufficiency

there is a deceased blood flow toward the tissues, producing ischemia pulses are usually diminished or absent sharp, stabbing pain occurs because of the ischemia, particularly with activityischemic ulcers and changes in the skin.

1. Age (elderly) – blood vessels become less elastic, becomethin walled and calcified – PVR – BP

2. Sex (male)3. Cigarette smoking

› nicotine causes vasoconstriction and spasm of the arteries – circulation to the extremities

› C02 inhaled in cigarette smoke reduces 02 transport to tissues

4. Hypertension – cause elastic tissues to be replaced by fibrous collagen tissue arterial wall become less distensible resistance to blood flow BP

5. Hyperlipedimia – atherosclerotic plaque6. Obesity – places added burden on the heart & blood

vessels› excess fat contribute to venous congestion

7. Lack of physical activity› Physical activity – promotes muscle contraction

venous return to the heart› aids in development of collateral circulation

8. Emotional stress – stimulates sympathetic N.S. - peripheral vasoconstriction BP

9. Diabetes mellitus – changes in glucose & fat metabolism promote the atherosclerotic process

10. Family history of arthrosclerosis

is a disorder in which there is an arteriosclerotic narrowing or obstruction of the inner & middle layer of the artery

most common cause of arterial obstructive disease in the extremities

the lower extremities are involved more than upper extremities

common site of disease – femoral artery, iliac arteries, popliteal arteries

in a diabetic, the disease becomes more progressive, affects the smaller arteries and often involves vessels below the knee

Sub-diaphragmatic aorta 21 – 24 mm Infra-diaphragmatic aorta 17 – 20 mm Common iliac artery 10 – 12 mm External iliac artery 8 – 10 mm Common femoral artery 7 – 9 mm Superficial femoral artery6 – 8 mm Popliteal artery 4 – 6 mm

Plaque formation on the intimal wall that causes partial or complete occlusion

Calcification of the medial layer and a gradual loss of elasticity weakens the arterial walls

predisposes to aneurysm, dilation or thrombus formation

artery is unable to transport an adequate blood volume to the tissues during exercise or rest

Intermittent claudication – most common› pain during exercise disappear w/in 1-2 mins. after

stopping the exercise or resting› the femoral artery is often affected – pain in the calf

muscle – common symptom

pain at rest is indicative of severe disease

› In advanced arteriosclerosis obliterans ischemia may lead to necrosis, ulceration and gangrene – toes and distal foot

Stage Complains

I Asymptomatic

II aII b

Mild claudication Moderate to severe claudication

III Ishemic rest pain

IV Ulcer or gangrene

Clinical classificationThe Rutherford classification

TASC II classification of femoral and popliteal lesions 

type A lesionssingle stenosis ≤ 10 cm in lengthsingle occlusion ≤ 5 cm in length

type B lesionsmultiple lesions (stenoses or occlusions), each ≤ 5 cmsingle stenosis or occlusion ≤ 15 cm not involving the infrageniculate popliteal artery

type C lesionsmultiple stenoses or occlusions totaling > 15 cm with or without heavy calcificationrecurrent stenoses or occlusions that need treatment after two endovascular interventions

type D lesionschronic total occlusion of the common or superficial femoral artery (> 20 cm, involving the popliteal artery)chronic total occlusion of the popliteal artery and proximal trifurcation vessels

Doppler ultrasonography –› audible tone produced in proportion to blood velocity› measure blood flow through vessels

Ankle brachial Pressure

The systolic pressure at any level of the lower extremity can be measured by positioning a pneumatic cuff at the desired site.

Any patent artery distal to the cuff that is accessible to Doppler ultrasound can be used for flow detection, but the posteriortibial (PT) and dorsalis pedis (DP) arteries are usually most convenient.

When the cuff is inflated to above systolic pressure, thearterial flow signal disappears. As cuff pressureis gradually lowered to slightly below systolic pressure, the flow signal reappears,and the pressure at which flow resumes isrecorded as the systolic pressure

In general, measurement of ankle systolicpressure is the most valuable physiologictest for assessing the arterial circulation inthe lower limb.

If the pressure measured bya cuff placed just above the malleoli is lessthan that of the upper arm, proximal occlusivedisease in the arteries to the lower limbis invariably present.

The ratio of ankle systolic pressureto brachial systolic pressure is called theankle-brachial index or ABI.

In the absence of proximal arterial occlusivedisease, the ankle-brachial index isgreater than 1 .0, (mean value of 1 . 1 1± 0.10)

values greater than 0.90 are typicallyinterpreted as normal.

Usually limbs with single-level occlusions have indexes greater than 0.5, and limbs withlesions at multiple levels have indexes lessthan 0.5

Many limbs with impending gangreneor ischemic ulceration have absent Dopplerflow signals at the ankle level.

ABPI Comment

> 1.3 Falsely high value (suspicion of medial sclerosis)

0.9 – 1.3 Normal finding 0.75 – 0.9

Mild PAD

0.4 – 0.75

Moderate PAD

< 0.4

Severe PAD

Calcification of vessel walls

Beaded appearance of color flow

Ankle pressure 280 mmHg

Brachial pressure 120 mmHg

ABPI 2.3

Falsely elevated recordings in diabetic patients

Calcified & rigid arterial walls

Narrow frequency band

Steep systolic increase

Quick drop

Early diastolic reverse flow ( of systolic flow amplitude)⅕

Late diastolic short forward flow

Cardiac pump function Cardiac insufficiency

Aortic valve function Aortic stenosis/insufficiency

Course of vessel Tortuosity

Vessel branching

Peripheral vascular resistance Peripheral inflammation

Polyneuropathy Warm or cold extremity Vaso-spastic disorders

Hyperemic (normal PSV& normal RT*) ExerciseFever Downstream infectionTemporary arterial occlusion by blood pressure cuff

Tardus-Parvus waveform (low PSV & longer RT)Distal to severe stenosis or occlusion

* Rise time: Time between beginning of systole & peak systole

Normal triphasic waveform

Normal DPA at rest

Monophasic hyperemic flow

Following exercise

Monophasic waveform

Normal PSV

Normal rise time

Proximal to stenosis

The character of Dopplersignals obtained proximal to an arterialobstruction depends on the capability ofthe collateral circulation. If there are wel ldevelopedcollaterals between the Dopplerprobe and the point of obstruction, thewaveform may be relatively normal.

If the Doppler probe is placed directly overa stenotic lesion, the signal has an abnormallyhigh peak systolic frequency. Thisreflects the increased flow velocity in thestenotic segment.

At site of stenosis

When a waveform is obtained from anarterial site distal to a stenosis or occlusion,a single, forward velocity component isobserved, with flow remaining above thezero baseline throughout the cardiac cycle.The peak systolic frequency is lower thannormal, and the waveform becomes flat androunded

Distal to stenosis

High resistance, low volume waveform

Characteristic shoulder on systolic downstroke

Due to pulse wave reflection from distal disease

ShoulderShoulder

Tardus: Longer rise time

Parvus: Low PSV

Severe stenosis or occlusion

Tardus-Parvus waveformDamping waveform

Increased systolic rise time

Loss of pulsatility

IF superficial femoral artery is patent, a PIless than 4 indicates a hemodynamicallysignificant aortoiliac lesion,

The PI of the normalcommon femoral artery has a mean value of 6.7.

More distally, the PI increases to 8 inthe popliteal and 14 in the PT artery

A PI value greater than or equal to 4 ispredictive of a hemodynamically normalaortoiliac segment.

Aorto-iliac: 25 %

Femoro-popliteal: 65%

Infra-popliteal: 10%

Proximal: 2 cm proximal to stenosis

At stenosis : Same Doppler angle if possible

Vr= psv ratio

SFA:

PSV of A 69 cm/sec

PSV of B 349 cm/sec

B / A 349 / 69 = 5

> 80% diameter stenosis

2 severe stenoses demonstrated in SFA

Areas of color flow disturbance & aliasing (arrows)

Drop-out of color flow signal in parts of lumen

Occlusion in CIA

Reversed flow in IIA (blue) to supply flow to EIA (red)

Ultrasound cannot provide reliable imaging if there are pooracoustic windows (eg, bowel gas attenuation, diffuse vascularcalcification, or metallic stents) or poor intrinsic echogenicityof the tissues.

Duplex scanning is time-consuming andinconvenient post-operatively – when the region of interestis obscured by dressings – and removing these can involveinfection risk.

DSA is the gold-standard for diagnostic imaging of PAD patients .

It enables large field-of view(FOV) imaging with the highest possible in-plane resolution compared to other modalities.

Drawbacks - catheterization, nephrotoxic contrast, exposure to high doses of ionizing radiation.

The procedure is associated with major risks such as allergic reactions, infections at the site of vascular access, iatrogenic arteriovenous fistulas, hematomas, dissections.

Digital subtraction angiography (DSA)

Complications are reported to occur in 0.17-7% of procedures, depending on thearterial viability, the size of the catheter, the experience of the clinician, and the location of the vascular access.

Given the invasiveness of the procedure, its applications is now limited topatients who require a surgical or percutaneous procedure for therapeutic purposes

•DSA is the "gold standard"  to diagnose, and often to treat vascular disease.  It involves getting detailed x-ray images of the arteries while injecting dye directly into the arteries.  For patients with poor kidney function, a non-toxic gas carbon dioxide can be used in place of IV dye.  Blockages can often be opened minimally invasively during an angiogram.

LEFT CIA STENOSIS

A) A catheter has been passed from the right common femoral artery and into the abdominal aorta during a digital subtractionangiogram. Contrast injection through the catheter reveals minor atherosclerotic wall abnormalities in the infrarenal aorta and the left common femoral artery

B) Lower limb images reveal diffuse atherosclerotic disease of the superfi cial femoral and popliteal arteries of both sides, with a focal area of significant stenosis inthe right popliteal artery.

CT Angiography (CTA)

CTA enables visualization of the entire peripheral vascular tree and offers information aboutlesion length, diameter, and morphology, as well as degree of calcification, and status of distalrunoff vessels.

A number of studies have compared CTA to the gold-standardDSA, showing comparable diagnostic accuracy and high confidence inclinical decision-making solely based on CTA .

CTA offers evaluation of plaque, calcification, and vascular wall, while DSAdepicts only arterial lumen.

Technical limitations ---- inability to

characterize calcified lesions, particularly in smaller vessels, due tobeam-hardening artifacts.

Drawbacks – radiation doze nephrotoxicity of contrast, which is contraindicated in patients with decreased renal function and renalinsufficiency.

 CTA image of the iliofemoral arteries. Severe, focal stenosis (arrow) is present in the right mid-to-distal superficial femoral artery

MR Angiography (MRA)

CE-MRA is similar in set-up and diagnostic quality to CTA.

CE-MRA methods rely on an injection of contrast material, which alters the magneticproperties of blood.

Peripheral MRA is routinely performed with gadolinium (Gd)-based contrast agents .

As vascular contrast isrelatively independent of flow-dynamics, CE-MRA can be used for large field-of-view (FOV) imaging.

For assessment of hemodynamically significantdisease Gd-MRA has reported sensitivities of 89-99.5% and specificities of 95-99% compared to DSA.

Advantages of CE-MRA over CTA === no ionizing radiation ability to depict lumen of calcified vessels.

Limitations == cost, scan time metal artifacts from stents and surgical clips.

Association between nephrogenic systemic fibrosis and gadolinium contrast has limited the applicability of CE-MRA in kidney disease patients.

Among the imaging modalities used in PAD evaluation, usg has no contraindications for patient with renal insufficiency.

Ultrasonography alone isinadequate for planning of surgical procedures because it does not provide accurate visualizationof the entire peripheral vascular tree.

Among the remaining modalities, both DSA and CTA,given their exposure to nephrotoxic contrast material and ionizing radiation, are unsafe for kidney disease patients.

Recent association between nephrogenic systemicfibrosis and gadolinium contrast has challenged the safety of CE-MRA as well

ContrastenhancedperipheralMRA

Symptomatic iliac artery occlusive disease, diagnosed with gadolinium-enhanced MRangiography. (a) Coronal MIP image from a gadolinium-enhanced 3D MR angiographic study performed with administration of gadopentetate dimeglumine demonstrates bilateral severe proximal iliac artery stenoses, with the right greater thanthe left (arrows). (b) The next anatomic station was imaged 10 minutes after the preceding study with a second dose of gadopentetate Dimeglumine by using a slightly faster sequence. There is no occlusive disease.

Unlike DU, MRAallows simultaneous angiographic as well as anatomicalvolume acquisition of the whole body in seconds whilstmaintaining high spatial resolution.

This allows both luminaland extra-luminal pathology to be shown simultaneously,although magnetic resonance imaging is poorer for bonyanatomy than computed tomography

Like DSA, contrast enhanced magnetic resonance imaging issensitive to patient motion artefacts. If there is patient motionbetween the mask acquisition and postcontrast acquisition,there will be image degradation following subtraction.

Magnetic resonance cannot image calcification or steelstents; causes susceptibility artefactsrecognizable as signal voids in the image.

Metallic structureswithin the vessel lumen or adjacent to the vessel may causemagnetic susceptibility artefacts that obscure the vessel lumenleading to a false diagnosis of a stenosis or obstruction.

Non-Contrast Magnetic Resonance Techniques for Peripheral Angiography

In recent years there has been a renewed interest in unenhanced techniques, determined by two major factors.

(1) improvements in MRI hardware and software havereduced acquisition times and made non-contrast imaging clinically practical

(2) concerns about NSF in advanced renal disease patients

Non-contrast MRA techniques rely on flow-induced changes in the longitudinal ortransverse magnetization of blood to obtain contrast between the vasculature and stationarybackground without administration of exogenous contrast material.

Four major approaches forartery-background contrast generation exist:

(1) Time-of-flight techniques (TOF) rely on differences in exposure to radiofrequencyexcitation between stationary tissue within the volume of interest and blood protonsflowing into the imaging slab from outside the FOV.

(2) Phase-contrast MRA relays on measurable velocity-induced changes in the phase ofthe blood signal

(3) ECG-triggered subtraction techniques relay on the difference in arterial flow velocitybetween systole and diastole; either gradient echo or fast spin-echo read out can beused

(4) Flow-independent angiography uses an acquisition that naturally provides bright bloodsignal weighting, combined with inversion-recovery and T2 preparation to nullthe signal of background tissues.

Currently, the MR angiographic approachto the tibial vessels is dominatedby the use of TOF techniques

This flow-dependent strategy circumventsthe challenge of achieving a sufficientconcentration of contrast mediumto effectively demonstrate the distal arterialVessels.

At present, TOF imagingoffers the surgeon sufficient informationto make the primary surgical decisions

Overestimation of segmental occlusions with TOF imaging. (a) Coronal MIP imageobtained with TOF imaging demonstrates bilateral iliac artery occlusions, with right greater than left.

(b) MIP image from a gd-enhanced 3D MR angiogram shows a shorter length of each occlusion compared with a.

The depiction of the right hypogastric artery which was not seen with TOF imaging. Suppression of thesignal from retrograde flow is a major limitation of TOF strategies designed to eliminate venoussignal.

Vascular calcifications in a patient with diabetes mellitus. A, Coronal thin section maximum intensity projection (MIP) of a computed tomography angiography of the tibial peroneal runoff vessels demonstrating how dense calcifications in this patient population obscures analysis of the lumen.

B, Contrast-enhanced magnetic resonance angiography is insensitive to vascular calcification as well as bone, simplifying image interpretation as demonstrated in this full-volume MIP from the same patient as in A.

– directed toward prevention of vessel occlusion use of vasodilatorsSurgical intervention – in advanced disease – ischemic

changes and pain severely impairs activity Embolectomy

› removal of a blood clot, done when large arteries are obstructed

Endarterectomy› is removal of a blood clot and stripping of

atherosclerotic plaque along with the inner arterial wall. Arterial by-pass surgery

› an obstructed arterial segment may be bypassed by using a prosthetic material (Teflon) or the pt’s. own artery or vein (saphenous vein)

Primary treatment strategy according TASC severity

TASC A - endovascular therapyTASC B - endovascular therapyTASC C - surgical therapy (if patient is able to be operated, otherwise endovascular therapy)TASC D - surgical therapy

Endarterectomy

Percutaneous Transluminal Angioplasty › The balloon tip of the catheter is inflated to provide

compression of the plaque Amputation

› with advanced atherosclerosis & gangrene of extremities

› toes are the most often amputated part of the body

FA lumen filled with hypoechoic thrombus or embolus

Good delineation of vessel wall without signs of plaque

Normal flow in adjacent FV

.

Aneurysm Diameter increase > 50% of normal expected

diameter Ectasia Diameter increase < 50% of normal expected

diameter

Considerable variability in normal diameter of arteries

Depends on physical size, sex, & age

Considerable variability in normal diameter of arteries

Depends on physical size, sex, & age

.

True aneurysm

False aneurysm

Dissecting aneurysm

.

Sonography is the recommended non-invasive

technique for the postoperative monitoring

of bypass graft patency

Sonography is the recommended non-invasive

technique for the postoperative monitoring

of bypass graft patency

Synthetic graft PTFE* Above knee

Autologous vein

* PTFE: Polytetrafluoroethylene

Aorto-bi-femoral graft Femoral-to-femoral artery bypass graft

Peripheral arterial bypass graft – 1

Femoro-Popliteal Above Knee

Femoro-Popliteal Below Knee

Femoro-Tibial Below Knee

Composite PTFE & vein graft

Slightly dilated area

corresponding to valve site

In situ vein graft

Hyperemic flow often seen

in early postoperative period

Hyperemic monopahasic flow Pulsatile flow

Over time, flow normally

assumes a pulsatile flow

Average PSV

from 3 – 4 sites

without stenosis

Graft flow velocity

Normal PSV: 45 – 180 cm/s

Atherosclerosis

Graft degeneration

Neointimal hyperplasia

Technical faults