Peripheral arterial disease
The differences between atherosclerosis, arteriosclerosis, and Monckeberg sclerosis:
Arteriosclerosis
It is a general term that refers to the hardening and thickening of arterial walls. There are two main types of arteriosclerosis: atherosclerosis, and monckeberg sclerosis.
Atherosclerosis
Definition: It is a specific form of arteriosclerosis characterized by the accumulation of deposits of lipids (fat), cholesterol, calcium, and other substances in the intimal layer of the arteries.
Effect: This build-up, known as atherosclerotic plaque, can narrow or obstruct arteries, reducing blood flow and increasing the risk of cardiovascular events, such as myocardial infarction and stroke.
Location: It mainly affects large and medium-sized arteries, such as the coronary, carotid, and peripheral arteries.
Monckeberg’s sclerosis:
Definition: Also known as calcifying medial sclerosis, it is a form of arteriosclerosis that involves calcification of the middle layer (tunica media) of muscular arteries.
Effect: Unlike atherosclerosis, Monckeberg sclerosis does not cause narrowing of the arterial lumen but can lead to significant arterial wall stiffness.
Location: It is common in elderly patients, those with chronic kidney disease, diabetes mellitus, and diseases that cause vascular calcification.
Consequence: May predispose to aneurysms due to the rigidity of the arterial walls.
Summary
Arteriosclerosis: General term for hardening of the arteries.
Atherosclerosis: Accumulation of lipid plaques, cholesterol, and other substances in the intima layer of the arteries, leading to narrowing and obstruction.
Monckeberg sclerosis: Calcifying the medial layer of muscular arteries, causing stiffness but without narrowing the lumen.
Atherosclerosis is a chronic, systemic, progressive process that begins in youth and is triggered by an inflammatory and fibroproliferative response.
The essential physiology of atherosclerosis begins in childhood and is an ongoing process that cannot be stopped entirely. However, it can be slowed down or managed to avoid complications. We remember the fatty streaks in children.
It’s important to note that the two different forms of atherosclerosis can coexist in the same individual. This complexity underscores the challenge of managing cardiovascular health and the need for a comprehensive approach.
Atherosclerosis prefers arterial bifurcations, angles, fixed arteries, and posterior regions of arteries. At points furthest from the ends, it takes on a circular pattern.
Atherosclerosis increases the intima’s permeability to lipoproteins, leading to cholesterol accumulation in the vascular wall. This accumulation, especially in the first two layers, causes stenosis. The adventitia, the outermost layer, is usually spared. The prognosis is worse the more distal the injury, increasing the chance of amputation.
The distribution pattern of atherosclerosis varies with risk factors. A person who smokes without hypertension or diabetes tends to have atherosclerosis in the aortoiliac region. An exclusive diabetic tends to present atherosclerosis in the infrapatellar segment, sparing the digital arteries.
When atherosclerosis affects he entire arterial territory, the patient is usually diabetic, hypertensive, and smokers.
Risk factors for atherosclerosis:
- Age (over 50 years old, especially over 70)
- Hyperlipidemia or hypercholesterolemia
- Smoking
- Hypertension
- Diabetes
- Hyperhomocysteinemia (minor)
- Fibrinogen (minor)
Semiological findings on physical examination:
- Change in the legs: Decrease in blood supply reflected in the absence of hair, especially from the middle to the bottom of the leg. Often, the patient thinks it is due to wearing socks.
- Muscle hypotrophy: Underdeveloped muscles.
- Paleness and reactive redness: Important indicators.
- Thermal gradient: Cold member or with reduced temperature.
- Absence or decrease in pulses: Clear indicator of circulatory problems.
- Ankle-brachial index (ABI): Remember that patients with chronic kidney disease and diabetics may have false results due to calcification of the arteries in the lower limbs.
Ankle-brachial index (ABI)
The ABI reflects the patient’s symptoms with a moderate correlation; it is acceptable but not perfect.
< 0.9 diagnosis of peripheral arterial disease
< 0.7 claudication
< 0.5 threatened limb viability (or Systolic blood pressure < 40mmHg)
< 0.3 critical ischemia
Intermittent claudication
It is a characteristic sign of peripheral arterial disease. It occurs as muscle pain triggered by physical activity and improves with rest or when leaving the foot hanging. The claudication happens because, during physical activity, the limb needs more blood than the arteries can supply, leading to pain. When the patient stops or puts the foot down, gravity helps improve circulation, decreasing pain.
Critical ischemia
It is the most severe manifestation of peripheral arterial disease. It occurs when systolic blood pressure in the ankle arteries is very low, below 40 mmHg, causing pain at rest, or below 60 mmHg, when there is an associated trophic lesion. Critical ischemia indicates that the limb is at risk of losing its viability.
Resting pain
It is a sign of critical ischemia. It occurs when blood pressure is so low that it cannot meet the metabolic demands of the tissue, even at rest, causing constant pain. Trophic injury, a complication of rest pain, also indicates critical ischemia and is characterized by tissue loss due to digital ischemia, which can be spontaneous or secondary.
The Fontaine and Rutherford classifications (for peripheral arterial disease)
Fontaine: from 1 to 4
1: Asymptomatic
2: Claudication (A: not disabling, B: disabling)
3: Pain at rest (Critical ischemia)
4: Ulcer or gangrene
Rutherford: from 0 to 6:
0: Asymptomatic
1-3: Claudication (mild, moderate, severe)
4-6: Critical ischemia (4: pain at rest, 5-6: trophic injury)
SVS also developed the WiFi classification, which considers three main criteria: wound, ischemia, and infection.
TASC Classification
It classifies patients by the severity of the arteriographic injury. TASC classifications exist for the aortoiliac, femoropopliteal, and infrapatellar territories.
TASC goes from A to D, classifying injuries according to arteriography. We can use CT angiograms to assess the extent and arterial involvement. The more extensive the lesion, the greater the severity, taking into account calcification and branch involvement.
Femoropopliteal TASC
TASC A
Single stenosis must be less than 10 cm or a single occlusion less than 5 cm.
TASC B
Multiple lesions, each smaller than or equal to 5 cm or an occlusion smaller than 15 cm, without involving the popliteal artery.
TASC C
Multiple stenoses or occlusions totaling more than 15 cm.
TASC D
Complete occlusion of the common or superficial femoral, with a length of 20 cm, involving the popliteal or proximal trifurcation.
To memorize TASC, you can focus on the extent of stenosis and occlusion:
Stenosis:
- Less than 10 cm (TASC A)
- Less than 15 cm (TASC B)
- Greater than 15 cm (TASC C)
- Greater than or equal to 20 cm (TASC D)
Occlusion:
- Less than 5 cm (TASC A)
- Lessthan 15 cm (TASC B)
- Greater than 15 cm (TASC C)
- Greater than or equal to 20 cm (TASC D).
Infrapatellar TASC
Classifies according to the target artery for revascularization. For example, if the target artery is the anterior tibialis, then it is classified based on that artery.
TASC A
It is a stenosis smaller than 5 cm.
TASC B
Multiple strictures smaller than 5 cm, totaling more than 10 cm, or an occlusion smaller than 3 cm
TASC C
Multiple stenoses or occlusions totaling more than 10 cm.
TASC D
Is the most complicated, with multiple stenoses or occlusions totaling more than 10 cm, with intense calcification and no collateralization.
Best Medical Therapy (BMT)
Overview
BMT focuses on removing or controlling risk factors and preventing complications. This involves:
- Stopping smoking
- Adjusting the diet
- Controlling diabetes, hypertension, and hyperlipidemia
- Practicing physical activity
An optimized clinical treatment should last at least 60 days.
Hypertension Control
Controlling hypertension is crucial but should be moderate. If ankle systolic blood pressure drops too low, it can cause more symptoms. Resting pain usually stops when systolic pressure is above 60 mmHg, resulting in an ankle-brachial index (ABI) greater than 0.5, provided there are no trophic lesions.
Increasing Walking Distance
The best way to increase walking distance is through physical activity, especially planned walking. Pharmacologically, cilostazol is the most effective option for this purpose.
Surgical Treatment
Surgical treatment is for patients with critical ischemia or those with claudication for very short distances who have not responded to clinical treatment. The goal is to increase blood flow to the extremity by ensuring digital pulsatile flow at the ankle.
Treatment Options
- Traditional surgery
- Endovascular surgery
- Hybrid surgery
- Primary amputation
- Sympathectomy
- Neurotripsy
Criteria for Procedure Selection
To determine the appropriate procedure, consider:
- Physiological reserve and surgical risk of the patient
- Topography and extent of the lesion
- Association and sequence of lesions
- Location of inflow and outflow
- Distance required for bypass or angioplasty
- Availability of vein or endovascular material
By considering these factors, you can choose the best approach for treatment.
Primary Amputations
Primary amputations are indicated for patients who do not have criteria for life-saving techniques or after these have been exhausted.
Endarterectomy
Endarterectomy is the removal of atheroma plaque through the opening of the artery. An endarterectomy spatula removes the intima and part of the media layer, leaving the second part of the media and the adventitia. This technique is only applicable for arteries of larger caliber and short occlusions, such as the common femoral, deep femoral (profundoplasty), aorta, and iliac arteries. It is unsuitable for extensive occlusions, such as the femoropopliteal artery.
Profundoplasty
Profundoplasty is important because deep femoral revascularization can increase infrapatellar perfusion through the geniculars, improving the ankle-brachial index even with the occluded femoropopliteal territory.
There are three ways to perform endarterectomy:
1. Traditional open technique: Longitudinal arteriotomy, plaque removal and arteriorrhaphy.
2. Open eversion technique: Completely sections the artery and uses the endarterotome or a Kelly for circumferential plaque removal.
3. Semi-closed technique with Voomar ring: The ring passes between the media and the adventitia, removing the plaque.
Bypass
Bypass connects two segments and is indicated for more extensive occlusions.
The donor artery must be significant, healthy, and proximal disease-free.
The receptor artery must be large and healthy up to the foot.
Arterial Substitute
Shunting with an autogenous vein is the best option, as it has the best patency rate. The in situ saphenous vein is preferable to the ex vivo saphenous vein (extraction and preparation outside the patient). Shunts with prosthesis (ringed PTFE, PTFE with heparin, or Dacron prosthesis) are justified only in the absence of a vein or when endovascular treatment is impossible.
When the recipient artery is infrapatellar, a Miller ring is necessary to use a prosthesis. This ring accommodates the prosthesis over the artery, avoiding direct trauma and disproportion of diameters.
Saphenous Vein In Situ
Benefits:
– Internal lining of living endothelium.
– Adaptation to the caliber of donor and recipient arteries.
– High rate of use of the saphenous vein.
– Does not require bench preparation.
Disadvantages:
– Need for valvulotomy.
– Competent valves can compromise flow.
– Large taxes stealing the flow.
Extraanatomical Bypass
Typically, an anatomical bypass is performed, following the trajectory of the native artery with an autologous substitute. However, there are situations in which anatomical bypass is not feasible, and in these cases, an extra-anatomical bypass is necessary. Extra-atomic bypass is when the substitute does not follow the trajectory of the native artery.
Indications:
– Previous infection.
– Difficult surgical access.
– Absence of a donor artery in a suitable location.
For example, the femoropopliteal bypass can be performed through the foramen ovale. When the usual anatomical path is impossible, an extra-anatomical segment is chosen.
Sequential Bypasses
They are used in multisegmental occlusions. An example is an iliac, femoral bypass, usually with distal anastomosis in the deep femoral artery, and distally with femoropopliteal bypass, with proximal anastomosis to the arterial substitute.
Sympathectomy
Lumbar sympathectomy is performed through sympathetic gangliectomy to promote peripheral vasodilation and increase blood supply. This procedure is reserved for extreme cases with small trophic lesions in patients with thromboangiitis obliterans, without diabetes mellitus (autosympathectomy), and without the possibility of revascularization. It can be performed using the open or phenolic puncture technique. A pre-procedure test can be performed by injecting lidocaine into the phenolic sympathectomy territory to measure toe temperature. The procedure can be considered adequate if the temperature increases by 1 to 2 °C.
Neurotripsy and Neuractomy
Description: Crushing or removing segments of sensory or mixed nerves to relieve intractable pain.
