August 12, 2021

Dr Tim Pearce Anatomy MannequinA vascular occlusion or VO is caused by a small quantity of dermal filler entering a vessel and interrupting the blood flow. But is it really that simple? Have you ever stopped to think if there is more to the types of vascular injuries which can be caused in medical aesthetic practice?

After reviewing a variety of different VO case presentations recently, Dr Tim Pearce thought it would be a great idea to discussion this topic further – after all, there is no one-size-fits-all vascular occlusion.

In this blog, Dr Tim explores the 8 different mechanisms, or types of occlusions, from vascular injury after dermal filler injection that can cause necrosis.

Dr Tim will be discussing more medical aesthetic training tips as part of his upcoming webinar series, so if you’re looking to increase your CPD-certified learning and want to learn more skills to make you a better practitioner, then step one is to register for the free webinars by Dr Tim.

What is a vascular injury?

necrosis diagramAt a basic level, a vascular injury, be it a compression, compromise, or occlusion, is a blocked or restricted vessel which means that blood flow is interrupted and there is no longer enough oxygen getting to the tissue in an area, which could ultimately lead to tissue death or necrosis.

8 different types of vascular injury and occlusion from dermal filler injection

Vascular injuries can be broken down into a variety of different types of vascular occlusion.

  1. Point occlusion – this is the simplest form of VO. It consists of the placement of a small quantity of dermal filler into a vessel, such as an artery, which blocks a small section of the artery, but not at a point where it is connected or anastomosed to other vessels. Thankfully, the network of nearby blood vessels should mitigate the severity of the complication and stop the immediate onset of necrosis whilst you treat the occlusion with hyaluronidase (in the case of hyaluronic acid or HA-based products). With a small amount of product, and a small occlusion, it may be difficult to detect a point occlusion immediately.
  2. Comprehensive occlusion – Starting from a point occlusion, if you go on to inject more dermal filler such that you introduce a significant volume or large bolus of product, this will cause a continuous occlusion of the vessel and will further impact anastomosed vessels nearby. A good example for illustration would be where the superior labial artery, above the upper lip, becomes occluded which goes on to impact and occlude the columellar artery which feeds the base of the nose. As well as the arteries mentioned, smaller capillaries and other vascular branches become occluded in a significant regional area of the face.
    This turns a point occlusion into a comprehensive occlusion because there is no longer any neighbouring vasculature that can ‘pick up the slack’ to maintain the blood supply to the tissues to keep them alive. The speed of impending necrosis is therefore increased due to the wider occlusion. Identifying a comprehensive occlusion is easier because there are usually many more visual clues within the anatomy. It may start with a small area of discoloration which will develop further over time, often along the path of the compromised artery.
    For additional guidance on using hyaluronidase in an emergency, read this blog on vascular occlusion: how much Hyalase (Hyaluronidase)? and download a template for a hyaluronidase consent form which will help you explain the risks of use to a patient.
  3. Anastomosis occlusion – This type of VO occurs when the anastomosis of a named vessel confuses the assessment of the source of the original occlusion or blockage. For example, there may be a situation where an aesthetic clinician is trying to decide if the source of an occlusion is the infraorbital artery, the facial artery, or the superior labial artery because the presentation appears to be everywhere. This is where the anastomosis between all these vessels becomes apparent. It is worth remembering that in facial anatomy textbooks, named vessels are often drawn in illustrations in isolation, as individual lines. However, this is not true to real life and these vessels are often connected or anastomosed by tiny vessels which can impact the immediate presentation of blockages within larger vessels.
    Limited edition facial anatomy posters are available to buy for your aesthetic business as a helpful tool to understanding the paths of the facial vasculature.
  4. Fragmenting filler occlusion – Upon emergency treatment of one of the above-mentioned vascular occlusions via administration of hyaluronidase to dissolve the HA filler product, it is very possible to create fragments of filler which go on to occlude smaller vessels. When dissolving hyaluronic acid-based dermal fillers, the HA gel is unlikely to dissolve immediately or in a homogenous manner, particularly with thicker products, leaving smaller fragments or clumps of gel as the enzyme breaks it down. Watch Dr Tim’s experiment where he compares dissolving hyaluronic acid gel with both saline and hyaluronidase. In vivo, the addition of vigorous massage to the emergency dissolving protocol could disperse product and in theory allow tiny fragments of HA gel to pass along nearby vessels causing localised impending necrosis.
  5. Venous emboli or venous occlusion – Although it is possible to cause necrosis in areas such as the eye with a venous embolism in the retinal veins, this is due to the restricted vasculature and ‘end vein’ nature of many of the vessels within the area. It is much more difficult to cause a necrotic injury with a venous embolism or venous injection of filler in the skin. Presentation in such cases will be like a deep vein thrombosis (DVT) – the area will swell, accumulate fluid, and appear warm to the touch. Occluding a vein in the face may therefore present with discolouration, discomfort, and inflammation, but is not a true case of impending necrosis. In such cases, simple massage can relieve the problem and disperse the product into the circulatory system where it will no longer cause a blockage.
  6. Compression occlusion – This is distinct from a VO caused by an intravascular injection because it is caused by pressure from the dermal filler product compressing the blood vessels from the outside which restricts the blood flow within the capillaries. This presentation is more likely to happen in areas of the face where the skin is tight, and you are relying predominantly on capillary blood flow. A good example is the tip of the nose. This may present with a redness at the end of the nose which can take a little time to settle. In this instance, the redness is due to the capillaries compensating for the pressure in a similar manner to that seen with early-stage pressure sores. If the compression is large enough, and left for a long time, with the presentation of redness persisting beyond 48 hours, especially with pain or ache in the nose, then there is an increased risk of causing necrosis. You cannot rely on the capillary refill test (CRT) for identifying a compression occlusion.
  7. Spasm occlusion – Choke vessels, defined by Taylor et al. in Angiosome Theory as ‘reduced-calibre anastomosing vessels which are normally the barrier in the vasculature’ are commonly referenced in plastic surgery. They have a special ability to lie dormant until needed and can both dilate to increase blood flow to an area and constrict to isolate individual angiosomes (an anatomical area of skin, tissue, and vasculature) from noxious substances which may be in a neighbouring angiosome. In the case of dermal filler treatment, this could apply to the inflammatory, short-chain, hyaluronic acid-based products. Such products could stimulate the choke vessels to lock down or spasm in the case of a VO and may explain why we sometimes see a delaying CRT in nearby tissue. Read more in this clinical paper on the importance of choke vessels in injectable fillers.
  8. Reperfusion injury – If you unblock a vessel, you could cause necrosis via a reperfusion injury, commonly well understood in patients following a heart attack. During an occlusion, the vascular system shuts down because no oxygen is reaching the area. As soon as you unblock the vessel, the injury may worsen, in part due to the build-up of free radicals. As oxygen re-enters the vessel it can damage and injure the cells within the vessel due to oxidative stress. Little is known about the manifestations or occurrence of reperfusion injuries in the skin, but aesthetic clinicians may encounter a worsening of the injury, even though the vascular compromise has been resolved.

Dr Tim Pearce Aesthetics eLearningDr Tim is keen to hear your experiences of unusual vascular occlusion presentations to prompt further learning and discussion within our community. Simply get in touch by leaving a comment on social media.

If this blog has given you food for thought about the MANY different types of vascular injury, then remember, prevention is your key to mitigating severe complications in aesthetic practice.

Read 5 critical mistakes clinicians make with vascular occlusions and download our guide to the 13 most dangerous areas to injection which includes a map of the facial vessels.

Aesthetics Mastery Show

FOREHEAD ANATOMY: When to use toxin vs filler & how to avoid complications

This blog follows our recent Aesthetics Mastery Show, in which Dr Tim Pearce discusses the 8 different mechanisms by which vascular injury after dermal filler can cause necrosis.

Are you still anxious about delivering cosmetic injectables safely?

If you want to learn more about mastering medical aesthetic treatments and complications or conquering the anxiety of where to place your needle, then register for the next Dr Tim webinar.

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Dr Tim Pearce eLearning

Dr Tim Pearce MBChB BSc (Hons) MRCGP founded his eLearning concept in 2016 in order to provide readily accessible BOTOX® and dermal filler online courses for fellow Medical Aesthetics practitioners. His objective was to raise standards within the industry – a principle which remains just as relevant today.

Our exclusive video-led courses are designed to build confidence, knowledge and technique at every stage, working from foundation level to advanced treatments and management of complications.

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