Hey , What’s that moving object over AML ? It looks odd, it doesn’t look like a thrombus or a vegetation.
Yes, I agree , its moving independently but I think , Its benign threads of fibrin attached to the valve .They are called as valvular strands.
Is it ?, I haven’t heard about it ! Can you please tell me something about it.
Strands are highly mobile, fine, filiform threadlike excrescences that is seen arising from valvular structures. Synonym : Its same as Lambl’s excresceneces , the Czech physician who described it over Aortic valve in 1860.
The following TEE clip shows strands attached to Aortic valve
Incidence
Reported Incidence of valvular strands varies .Some reports suggested it may be up to 5-10 % .( SPARC study Mayo clinic 1999 its staggering 46 % !)The reason for such high incidence is, many of us are still not clear what we refer to as strand.The imaging modality also has a say. With improving resolution of TTE and liberal TEE use more strands are detected .A recent large study from Israel , suggest a good news , in large population based study (21,000) true strands are observed in just around 1 %.(Marina Leitman 2014 )
Is it Physiological or Pathological ?
The valve closure lines are physiologically stressed , some amount of denudation of endothelium is expected .This leads to a thrombus formation along with the exposed mucopolysacchride layers of the valve form a filiform ,filamentous structure. .To call it physiological or pathological is left to our wisdom and perception. The size however matters. It could be the reason behind many unexplained strokes.
What is the natural history of these strands ?
Its difficult to believe It may persist for lifetime.If its truely fibrinous strands it may have a life cycle and disappear.
Size
Should be less than 1 mm.
Length varies between 3 mm to 5 mm
Location
Can be seen in any valve or even in aortic root.
Attachment : Atrial side of mitral valve and ventricular side of Aortic valve.
Strands over prosthetic valve is also reported.
Clinical significance
It has three common issues.
One: Getting confused with other more pathological entities.
Two : Risk of stroke.
Three: Nidus for normal native valve endocarditis ?
Strands may closely mimic
- Vegetations
- Bland thrombus
- Redundant leaflet /Chrodae (Marfan and variants)
- Disrupted chordae (After MVR)
- Flail leaflet
- Fibroelastomas
Risk of dislodgement and stroke
These strands are minute. It seems plausible dislodgement need not necessarily result in stroke or other organ ischemia.We don’t know whether it gets dissolved on transit.However the risk of stroke is increased in most reports except few studies(Roldan).
Management
First question to ask is , Should we inform our patients about these ubiquitous accessory valve tissues if detected incidentally ?
Largely benign and can be ignored in most.A follow up echo may be adviced once in a year or 2. (I have one anxious patient after I reported such strands in Marfan syndrome )
In patients who has h/o stroke presence of these strands gains importance and is an indication for anticoagulation.
Surgical excision of large strand is a dramatic option and is rarely performed.
Queries with no answers
Is it accessory valvular (mesenchymal) tissue ?
Does Atheromatous plaque contribute to these strands in Aortic valve ?
Strands , if disappears by natural means , do they regrow from the same spot of raw surface ?
Final message
Fibrous strands detected over the valves by routine echo are uncommon .However , It may give considerable anxiety if documented and reported to our patients and physicians .Though these have negligible clinical significance , the risk of stroke is increased in those with large strands.
Reference
2.Aziz F1, Baciewicz FA Jr Lambl’s excrescences: review and recommendations.Tex Heart Inst J. 2007;34(3):366-8.
Dr.S.Venkatesan MD 