Mitral annular systolic velocity
LV S′ (LVSm) · Pulsed tissue Doppler, apical 4-chamber, sample volume 5–10 mm on the septal and lateral mitral annulus
Normal range & thresholds
Septal S′ ≈7–11 cm/s; lateral S′ ≈9–14 cm/s. An average S′ <8 cm/s (or septal <7 cm/s) predicts LVEF <50% with good accuracy. Velocities fall by roughly 1 cm/s per decade, so age the number before calling it abnormal.[1,2,55]
The 5-5-5 sign: septal s′, e′ and a′ all <5 cm/s in a thick-walled ventricle is a strong red flag for cardiac amyloidosis.[2,30]
The 5-5-5 sign: septal s′, e′ and a′ all <5 cm/s in a thick-walled ventricle is a strong red flag for cardiac amyloidosis.[2,30]
Pathophysiology
Longitudinal subendocardial fibres shorten first and fail first, because the subendocardium is the most vulnerable layer to ischaemia, fibrosis, infiltration and raised wall stress. Annular systolic velocity is a direct sample of that longitudinal shortening, so it falls before ejection fraction — ejection fraction is defended for a long time by preserved circumferential and radial mechanics.[108]
Raised by
- Hyperdynamic states — sepsis, anaemia, thyrotoxicosis, pregnancy, arteriovenous fistula
- Inotropes and exercise (a normal contractile reserve response)
- Significant mitral regurgitation — the annulus moves further into a low-impedance atrium; a falsely reassuring value
- Young age and athletic training
Lowered by
- Any cause of systolic dysfunction — ischaemic, dilated, toxic, inflammatory
- Infiltrative and restrictive disease — amyloid, Fabry, sarcoid, haemochromatosis: characteristically the earliest abnormality, with a still-normal LVEF
- Hypertrophic cardiomyopathy and severe hypertensive LVH
- Constrictive pericarditis at the lateral annulus (annulus reversus: lateral lower than septal)[57]
- Mitral annular calcification, prior mitral surgery or annuloplasty ring (tethering)
- Post-cardiac-surgery, after any pericardiotomy
- Ageing
Technique & pitfalls
- Angle of insonation must be <20° to annular motion — this is a Doppler velocity and it is cosine-dependent.
- Sample volume 5–10 mm, positioned on the annulus, kept within the annular excursion throughout the cycle.
- Sweep speed 50–100 mm/s; minimise wall-filter and gain; measure the peak of the systolic wave, excluding the isovolumic spike.
- Report both septal and lateral, and their average; report which was used.
- In regional disease, average the six basal segments or state that the value is regional — a single site does not represent a ventricle with an anterior infarct.
Pseudo-change & artefact
- Translation and tethering: the whole heart moving in a hyperdynamic chest, or an akinetic segment dragged by neighbours, both corrupt the value.
- Angle error: a 20° deviation removes ≈6% of the velocity; 30° removes 13%.
- Sample volume drifting into the LV cavity (velocity falls) or into the atrium.
- Load: velocity falls with hypovolaemia and rises with volume loading — this is not a load-independent index.
- Pacing, LBBB and post-surgical septal motion selectively reduce the septal value.
- Wall-filter set too high truncates low velocities and manufactures a ‘5-5-5’ pattern.
Treatment thresholds
- No treatment threshold is defined by S′ alone in any current guideline — state this explicitly rather than implying one.
- Its guideline role is diagnostic: as part of the amyloid red-flag constellation[30], as a cross-check on a visually estimated LVEF, and as a surrogate for systolic function when endocardial borders are poor and strain is unavailable.[17]
- S′ contributes to the myocardial performance (Tei) index and to contractile-reserve assessment during low-dose dobutamine in low-flow low-gradient aortic stenosis.[5,28]
Next step
- Next: if S′ is low with a normal LVEF, measure global longitudinal strain — the same physiology, quantified and less angle-dependent.
- Then: look at wall thickness, ECG voltage and the strain map for apical sparing.
- Then: CMR with T1/ECV mapping, and the amyloid pathway (free light chains + bone scintigraphy) if the walls are thick.[30]
Drugs
- Rises with GDMT, revascularisation and resynchronisation, in parallel with ejection fraction.
- Rises acutely and non-specifically with any inotrope or with exercise.
- Falls with cardiotoxic chemotherapy, often before LVEF moves.[15]
- Beta-blockade lowers it acutely (rate and inotropy) while improving it chronically — time the study consistently.
Reversibility
Tracks the underlying systolic function. Reversible in the same proportions as ejection fraction (tachycardia-induced, takotsubo, myocarditis, alcoholic: large; established scar or amyloid infiltration: minimal). The post-cardiac-surgery fall in septal S′ is largely permanent yet clinically benign — do not read it as new dysfunction.[71]