Peripheral arterial Disease (Lower Limb)
Peripheral arterial diseases (PADs) refer to all arterial conditions except those affecting the coronary arteries and the aorta. It’s important to distinguish this term from ‘peripheral artery disease’ (often used for lower extremity artery disease).
In addition to lower extremities, other areas like the carotid and vertebral arteries, upper extremities, mesenteric, and renal arteries can also be affected, primarily due to atherosclerosis. These collectively form the family of PADs. PADs can also affect other areas due to atherosclerosis.
History and Investigations Peripheral arterial Disease (PAD)
| History and Investigations | Association | Management |
|---|---|---|
| Smoking | Strong association with proximal disease - Aorto-ilio-femoral disease | Behavior modification therapy Nicotine replacement therapy Bupropion |
| Diabetes | 1. Strong association with distal disease - femoral-popliteal and tibial (below knee) 2. More likely to present with ulcer / gangrene. | Link |
| C-reactive protein (CRP) | Endothelial dysfunction + increased local inflammatory state + loss of NO leads to foam cell deposition leading to atheroma formation | |
| Hypertension | Strong association with proximal disease - Aorto-ilio-femoral disease | 1. Non Diabetic target B.P 140/90 mmHg 2. Diabetics and patients with chronic renal disease target B.P 130/80 mmHg 3. Systolic below 110-120 mmHg not recommended. 4. β - adrenergic blocking drugs, Diuretics, calcium antagonist, angiotensin-converting enzyme inhibitor and angiotensin receptor blocker can be provided to patient as monotherapy or in different combinations. 5. Angiotensin-converting enzyme inhibitor (ACE inhibitors) and angiotensin receptor blocker - to prevent risk for cardiovascular event. |
| Hyperlipidemia | Hydroxymethyl glutaryl (HMG) coenzyme - A reductase inhibitor (statin) - reduce the risk to CV event by 17% | |
| Family H/o atherosclerotic disease | ||
| History of poor renal function | eGFR<40 ml/min in diabetics | 1. Oral Hydration 2. Normal saline infusion |
| Signs of systemic atherosclerosis | 1. Cessation of cigarette smoking 2. Glycemic Control 3. Hypertension management 4. Dyslipidemia management 5. Antiplatelet Therapy |
|
| Vascular physical examination | Findings | Keypoints |
| Ankle brachial index (Resting) | Normal - 0.91 - 1.3 (if ABI > 1.3 this means that vessel are poorly compressible, occur in diabetic and elderly patients) Mild Obstruction - 0.70 - 0.90 Moderate Obstruction - 0.40 - 0.69 Severe Obstruction - < 0.40 | Normal individual have < 12 mmHg interarm systolic pressure difference |
| Toe Brachial index | Useful in individuals with non compressible posterior tibial or dorsalis pedis arteries | Requires small cuffs, difficult to measure |
| Segmental pressure examination | Pressure gradient between (> 20 mmHg between adjacent segment means significant stenosis) Brachial Artery and Upper thigh - Aortoiliac stenosis Upper and Lower thigh - Superficial femoral artery Lower thigh and Upper calf - distal superficial femoral or popliteal artery stenosis Upper and Lower calf - infra-popliteal disease | Might not be feasible in diabetic and elderly patients (non-compressible arteries) |
| Pulse Volume recording | Useful in individuals with non compressible arteries | Measured using Pneumoplethysmographic device |
| Treadmill exercise testing with and without pre and post exercise ABI | Helps differentiate claudication from pseudo-claudication When Resting ABI is normal | Need dedicated equipment which might not be easily available |
| Imaging Studies | Benefits | Keypoints |
| Doppler USG | Diagnosis and establishment for anatomic localization and severity of focal lower extremity arterial stenosis | Useful for graft surveillance |
| Magnetic resonance angiography (MRA) | PAD anatomy and patient selection for endovascular or surgical intervention. | May be contraindicated in patients with pacemaker, intracranial coils and clips. It can also overestimate degree of stenosis in arterial treated with metal stents |
| Computed tomography angiography (CTA) | PAD anatomy and patient selection for endovascular or surgical intervention. Patients with contraindicated for MRA. | Limited use in patients with poor renal functioning. |
| Contrast angiography | Gold standard | Risk of bleeding, sepsis, contrast allergy etc. Intervention if needed can be performed in the same session. |
Definitions used in the Management of Patients With Lower Extremity Peripheral Artery Disease
| Term | Definition |
|---|---|
| Claudication | Fatigue, discomfort, cramping, or pain of vascular origin in the muscles of the lower extremities that is consistently induced by exercise and consistently relieved by rest (within 10 min). |
| Acute limb ischemia (ALI) | 1. Acute (< 2 weeks), 2. Severe hypoperfusion of the limb characterized by these features: pain, pallor, pulselessness, poikilothermia (cold), paresthesias, and paralysis. 3. One of these categories of ALI is assigned: (Using Rutherford classification for acute limb ischemia) I - Viable Limb IIa - Marginally threatened or IIb - Immediately threatened. III - Irreversible Major tissue loss or permanent nerve damage inevitable |
| Tissue loss | Minor - nonhealing ulcer, focal gangrene with diffuse pedal ischemia. Major - extending above transmetatarsal level; functional foot no longer salvageable. |
| Critical limb ischemia (CLI) | A condition characterized by chronic (≥2 wk) ischemic rest pain, nonhealing wound/ulcers, or gangrene in 1 or both legs attributable to objectively proven arterial occlusive disease. The presentation of CLI can be discomfort in supine position, disturbed sleep, need for narcotic medication (absence of pain in patients with diabetes). Arterial disease can be proved objectively with ABI, TBI, TcPO2 , or skin perfusion pressure. If untreated major limb amputation in 6 months. |
| Functional status | Patient’s ability to perform normal daily activities. |
| Nonviable limb | A condition affecting an extremity (or a part of it) in which treatment cannot restore motor function, neurological function, or tissue integrity. |
| Salvageable limb | A state of an extremity where, if treated, there is potential to ensure its viability and maintain motor function, particularly in the weight-bearing section of the foot. |
| Structured exercise program | There are 2 types of structured exercise program for patients with PAD: 1. Supervised exercise program 2. Structured community- or home-based exercise program. |
| Supervised exercise program: | 1. This is a exercise program conducted in a hospital or outpatient setting, focusing on intermittent walking as a form of treatment. 2. Each session involves a minimum of 30 to 45 minutes of training, conducted at least three times a week for a minimum of 12 weeks. 3. The training consists of alternating periods of walking to the point of moderate-to-maximum claudication (pain caused by reduced blood flow) with periods of rest. 4. Additionally, there are warm-up and cool-down periods before and after each walking session. |
| Structured community- or home-based exercise program: | 1. This is a exercise program designed to be carried out in the patient's own environment rather than a clinical setting. 2. In this self-directed program, healthcare providers prescribe an exercise routine similar to what would be provided in a supervised program. 3. Patients receive counseling to ensure they know how to start, sustain, and gradually challenge their walking routine (either by increasing distance or speed). 4. This program may also include strategies to support behavioral changes, such as health coaching and the use of activity monitors. |
| Emergency versus urgent | 1. An emergency procedure is necessary when immediate action is required to prevent a life-threatening situation or serious limb damage, usually less than 6 hours. 2. An urgent procedure, on the other hand, is needed when there's some time for a limited evaluation. It's performed within 6 to 24 hours, often to address a situation where delaying intervention could lead to a life-threatening condition or significant limb damage. |
Differentials for Peripheral arterial disease:
| Condition | Location | Characteristic | Factors increasing pain | Factors decreasing pain | Keypoints |
|---|---|---|---|---|---|
| Symptomatic Baker’s cyst | Behind knee, down calf | Swelling, tenderness | Exercise | None | Not intermittent |
| Venous claudication | Entire leg, worse in calf | Tight, bursting pain | Walking | Rest and Limb elevation - slow relief | History of iliofemoral deep vein thrombosis; edema; signs of venous stasis |
| Chronic compartment syndrome | Calf muscles | Tight, bursting pain | Extensive Exercise (jogging) | Rest | Typically heavy muscled athletes |
| Spinal stenosis | Often bilateral buttocks, posterior leg | Pain and weakness | Walking and Exercise | Rest and lumbar spine flexion | Worse with standing and extending spine; History of back problems; worse with sitting; relief when supine or sitting |
| Nerve root compression | Radiates down leg | Sharp lancinating pain | Induced by sitting, standing, or walking | Present at rest | History of back problems; worse with sitting; relief when supine or sitting |
| Hip arthritis | Lateral hip, thigh | Aching discomfort | Exercise - variable degree | Avoid weight bearing | Symptoms variable; history of degenerative arthritis |
| Foot/ankle arthritis | Ankle, foot, arch | Aching pain | Exercise - variable degree | Avoid weight bearing | Symptoms variable; may be related to activity level or present at rest |