Diastolic Function Assessment by Echo
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Direct answer
Nearly half of all heart failure patients have a preserved ejection fraction, which makes diastology a core cardiac-technology skill, built on four measurements: the transmitral E and A wave velocities, the septal and lateral e′ (e prime) tissue velocities, the E/e′ ratio, and the left atrial volume index. E/e′ under 8 suggests normal left atrial pressure and above 14 elevated pressure, with septal e′ below 7 cm/s and lateral e′ below 10 marking impaired relaxation. Grading follows the pattern: Grade I is impaired relaxation (E/A below 0.8 with normal filling pressures), Grade II is pseudonormalisation (E/A 0.8-2 that conceals elevated pressures — exposed by E/e′ above 14, an LA volume index above 34 mL/m², or a Valsalva manoeuvre that drops E below A), and Grade III is restrictive filling (E/A of 2 or more with rapid deceleration).
What you must remember
- The four-variable panel (ASE/EACVI algorithm): mitral annular e′ (septal less than 7, lateral less than 10 cm/s abnormal), average E/e′ (over 14 elevated, under 8 normal), LA volume index (over 34 mL/m² abnormal), and peak tricuspid regurgitation velocity (over 2.8 m/s abnormal); more than half abnormal grades dysfunction.
- E/A ageing grammar: a young athlete may show E/A of 2 with normal pressures; an 80-year-old with E/A 0.7 may be simply old — age-adjust interpretation before labelling pathology.
- Grade I (impaired relaxation): E/A below 0.8, E deceleration time prolonged (over about 240 ms), E/e′ under 8 — pressures normal, relaxation slow, mild symptoms on exertion.
- Grade II (pseudonormal): E/A 0.8-2 looking "normal" but betrayed by E/e′ over 14, dilated left atrium, TR velocity over 2.8 m/s, and Valsalva reversal (E/A dropping below 1 with the strain).
- Grade III (restrictive): E/A at least 2, E deceleration time short (under about 160 ms), E/e′ over 14 — high filling pressures, poor prognosis, and reversible only if Valsalva improves it.
- Valsalva mechanics: the strain drops venous return and unmasks the impaired-relaxation pattern — a fall of E/A by 0.5 or more with strain indicates elevated resting filling pressure.
- Atrial fibrillation asterisk: with no A wave, diastology relies on E/e′, LA volume index and TR velocity alone; the E/A ladder does not apply.
Unmasking the pseudonormal ventricle
A 66-year-old hypertensive woman has exertional breathlessness with an ejection fraction of 58 per cent. The transmitral inflow looks reassuring — E 78 cm/s, A 62, E/A 1.26, "normal". The panel continues: septal e′ is 5 cm/s, lateral 7 (both abnormal); average E/e′ is 15; the LA volume index is 41 mL/m²; TR velocity 3.0 m/s. Three of four variables abnormal — the atrium has been absorbing pressure for years and its enlargement is the confession. For confirmation the Valsalva is coached properly (a 10-second strain against a closed glottis, not a puff of cheeks): the E wave falls, E/A inverts below 1, and the impaired-relaxation skeleton beneath the "normal" mask stands exposed. The report reads: Grade II diastolic dysfunction with elevated filling pressures — heart failure with preserved ejection fraction physiology, anchoring the clinical label HFpEF.
Where students slip
The exam-grade errors are predictable. The E/A ratio is treated as a standalone verdict, and pseudonormalisation — precisely because it looks normal — is the most missed grade. E/e′ is averaged wrongly: septal and lateral e′ should be averaged to interpret an average E/e′, and a septal-only E/e′ uses the septal cutoffs; mixing methods muddles the numbers. Annular calcification in the elderly and post-surgical mitral annuli drag e′ down independent of diastolic function, so an elderly hypertensive's E/e′ of 16 needs cautious phrasing, not an automatic "high pressures" verdict — the hedge examiners reward. Tachycardia fuses E and A waves, and first-degree block widens the gap; neither state allows honest grading, so the study notes "E-A fusion, grading deferred". And Grade III's reversibility is tested: restrictive filling that normalises with Valsalva carries a better outlook than fixed restrictive filling.
Frequently asked questions
How is the E/e′ ratio used to estimate filling pressures?
E (peak transmitral filling velocity) divided by e′ (annular relaxation velocity) estimates left atrial pressure: averages under 8 suggest normal pressures and over 14 elevated pressures, with 8-14 indeterminate and needing the rest of the panel.
What distinguishes Grade II from normal diastolic function?
Both show E/A between 0.8 and 2, but Grade II hides elevated pressures exposed by E/e′ over 14, LA volume index over 34 mL/m², TR velocity over 2.8 m/s, or Valsalva-induced E/A reversal. The dilated atrium is the chronic tell.
Why does the Valsalva manoeuvre help in diastology?
The strain cuts venous return, dropping preload; a pseudonormal pattern reverts to impaired-relaxation (E falling below A), while a truly normal ventricle scales down proportionately. A drop in E/A of 0.5 or more suggests elevated resting pressures.
Which measurements remain usable for diastology in atrial fibrillation?
E/e′, left atrial volume index and TR velocity — the E/A grading ladder collapses because there is no organised atrial contraction to generate an A wave. Irregular cycles also demand averaging over several beats.
What is a normal septal e′ velocity?
Septal e′ should be 7 cm/s or more and lateral e′ 10 cm/s or more in adults. Lower values indicate impaired myocardial relaxation, provided annular calcification and surgical changes are accounted for.